In situ ozone data for evaluation of the laser absorption spectrometer ozone remote sensor: 1979 southeastern Virginia urban plume study summer field program

Ozone data from the 1979 Southeastern Virginia Urban Study (SEV-UPS) field program are presented. The SEV-UPS was conducted for evaluation of an ozone remote sensor, the Laser Absorption Spectrometer. During the measurement program, remote-sensor evaluation was in two areas; (1) determination of the remote sensor's accuracy, repeatability, and operational characteristics, and (2) demonstration of the application of remotely sensed ozone data in air-quality studies. Data from six experiments designed to provide in situ ozone data for evaluation of the sensor in area 1, above, are presented. Experiments consisted of overflights of a test area with the remote sensor aircraft while in situ measurements with a second aircraft and selected surface stations provided correlative ozone data within the viewing area of the remote sensor

SBASI: Actuated pyrotechnic time delay initiator

A precision pyrotechnic time delay initiator for missile staging was developed and tested. Incorporated in the assembly is a single bridgewire Apollo standard initiator (SBASI) for initiation, a through-bulkhead-initiator to provide isolation of the SBASI output from the delay, the pyrotechnic delay, and an output charge. An attempt was made to control both primary and secondary variables affecting functional performance of the delay initiator. Design and functional limit exploration was performed to establish tolerance levels on manufacturing and assembling operations. The test results demonstrate a 2% coefficient of variation at any one temperature and an overall 2.7% coefficient of variation throughout the temperature range of 30 to 120 F. Tests were conducted at simulated operational altitude from sea level to 200,000 feet

Comparison of dermal and inhalation routes of entry for organic chemicals

The quantitative comparison of the chemical concentration inside the body as the result of a dermal exposure versus an inhalation exposure is useful for assessing human health risks and deciding on an appropriate protective posture. In order to describe the relationship between dermal and inhalation routes of exposure, a variety of organic chemicals were evaluated. The types of chemicals chosen for the study were halogenated hydrocarbons, aromatic compounds, non-polar hydrocarbons and inhalation anesthetics. Both dermal and inhalation exposures were conducted in rats and the chemicals were in the form of vapors. Prior to the dermal exposure, rat fur was closely clipped and during the exposure rats were provided fresh breathing air through latex masks. Blood samples were taken during 4-hour exposures and analyzed for the chemical of interest. A physiologically based pharmacokinetic model was used to predict permeability constants (cm/hr) consistent with the observed blood concentrations of the chemical. The ratio of dermal exposure to inhalation exposure required to achieve the same internal dose of chemical was calculated for each test chemical. The calculated ratio in humans ranged from 18 for styrene to 1180 for isoflurane. This methodology can be used to estimate the dermal exposure required to reach the internal dose achieved by a specific inhalation exposure. Such extrapolation is important since allowable exposure standards are often set for inhalation exposures, but occupational exposures may be dermal

The Application of a Trade Study Methodology to Determine Which Capabilities to Implement in a Test Facility Data Acquisition System Upgrade

More and more test programs are requiring high frequency measurements. Marshall Space Flight Center s Cold Flow Test Facility has an interest in acquiring such data. The acquisition of this data requires special hardware and capabilities. This document provides a structured trade study approach for determining which additional capabilities of a VXI-based data acquisition system should be utilized to meet the test facility objectives. The paper is focused on the trade study approach detailing and demonstrating the methodology. A case is presented in which a trade study was initially performed to provide a recommendation for the data system capabilities. Implementation details of the recommended alternative are briefly provided as well as the system s performance during a subsequent test program. The paper then addresses revisiting the trade study with modified alternatives and attributes to address issues that arose during the subsequent test program. Although the model does not identify a single best alternative for all sensitivities, the trade study process does provide a much better understanding. This better understanding makes it possible to confidently recommend Alternative 3 as the preferred alternative

Occupational safety considerations with hydrazine fuels

A simple pharmacokinetic model and a specially designed dermal vapor exposure chamber which provides respiratory protection were used to determine the rate of penetration of hydrazine and 1,1-dimethylhydrazine (UDMH) vapor through the skin of rats. Parameters for the pharmacokinetic model were determined from intravenous and inhalation exposure data. The model was then used to estimate the skin permeation coefficient for hydrazine or UDMH vapor from the dermal-vapor exposure data. This analysis indicates that UDMH vapor has a relatively high permeability through skin (0.7 cm/hr), a value somewhat higher than was obtained for hydrazine by the same procedure (0.09 cm/hr). Based on these skin permeability results, a skin-only vapor exposure limit giving protection equivalent to the inhalation Threshold Limit Value (TLV) could be calculated. The current TLV's for UDMH and hydrazine are 0.5 and 0.1 ppm, respectively. The corresponding skin-only TLV equivalents, for personnel wearing respiratory protection, are 32 ppm for UDMH and 48 ppm for hydrazine. Should the proposed lowering to the TLV's for these compounds to 0.01 ppm be adopted, the equivalent skin-only TLV's would become 0.64 ppm for UDMH and 4.8 for hydrazine

Experiment K-6-21. Effect of microgravity on 1) metabolic enzymes of type 1 and type 2 muscle fibers and on 2) metabolic enzymes, neutransmitter amino acids, and neurotransmitter associated enzymes in motor and somatosensory cerebral cortex. Part 1: Metabolic enzymes of individual muscle fibers; part 2: metabolic enzymes of hippocampus and spinal cord

The individual fibers of any individual muscle vary greatly in enzyme composition, a fact which is obscured when enzyme levels of a whole muscle are measured. The purpose of this study was therefore to assess the changes due to weightless on the enzyme patterns composed by the individual fibers within the flight muscles. In spite of the limitation in numbers of muscles examined, it is apparent that: (1) that the size of individual fibers (i.e., their dry weight) was reduced about a third, (2) that this loss in dry mass was accompanied by changes in the eight enzymes studied, and (3) that these changes were different for the two muscles, and different for the two enzyme groups. In the soleus muscle the absolute amounts of the three enzymes of oxidative metabolism decreased about in proportion to the dry weight loss, so that their concentration in the atrophic fibers was almost unchanged. In contrast, there was little loss among the four enzymes of glycogenolysis - glycolysis so that their concentrations were substantially increased in the atrophic fibers. In the TA muscle, these seven enzymes were affected in just the opposite direction. There appeared to be no absolute loss among the oxidative enzymes, whereas the glycogenolytic enzymes were reduced by nearly half, so that the concentrations of the first metabolic group were increased within the atrophic fibers and the concentrations of the second group were only marginally decreased. The behavior of hexokinase was exceptional in that it did not decrease in absolute terms in either type of muscle and probably increased as much as 50 percent in soleus. Thus, their was a large increase in concentration of this enzyme in the atrophied fibers of both muscles. Another clear-cut finding was the large increase in the range of activities of the glycolytic enzymes among individual fibers of TA muscles. This was due to the emergence of TA fibers with activities for enzymes of this group extending down to levels as low as those found in control soleus muscles. It would be interesting to know if this represents a transition stage, and whether with prolonged weightlessness most of the fibers would be transformed into a low glycogenolytic type

Three-Dimensional Structure of Conotoxin tx3a: A m-1 Branch Peptide of the M-Superfamily

The M-superfamily, one of eight major conotoxin superfamilies found in the venom of the cone snail, contains a Cys framework with disulfide-linked loops labeled 1, 2, and 3 (- CC1C2C3CC-). M-superfamily conotoxins can be divided into the m-1, -2, -3 and -4 branches, based upon the number of residues located in the third Cys loop between the fourth and fifth Cys residues. Here we provide a three-dimensional solution structure for the m-1 conotoxin tx3a found in the venom of Conus textile. The 15 amino acid peptide, CCSWDVCDHPSCTCC, has disulfide bonds between Cys1 and Cys14, Cys2 and Cys12, and Cys7 and Cys15 typical of the C1- C5, C2-C4, and C3-C6 connectivity pattern seen in m-1 branch peptides. The tertiary structure of tx3a was determined by 2D 1H NMR in combination with the combined assignment and dynamics algorithm for nuclear magnetic resonance (NMR) applications CYANA program. Input for structure calculations consisted of 62 inter- and intraproton, 5 phi angle, and 4 hydrogen bond constraints. The root-mean-square deviation values for the 20 final structures are 0.32 +/- 0.07 Å and 0.84 +/- 0.11 Å for the backbone and heavy atoms, respectively. Surprisingly, the structure of tx3a has a “triple-turn” motif seen in the m-2 branch conotoxin mr3a, which is absent in mr3e, the only other member of the m-1 branch of the M-superfamily whose structure is known. Interestingly, injection of tx3a into mice elicits an excitatory response similar to that of the m-2 branch peptide mr3a, even though the conotoxins have different disulfide connectivity patterns

In situ ozone data for comparison with laser absorption remote sensor: 1980 PEPE/NEROS program

Several sets of in situ ozone (O3) measurements were made by a NASA aircraft in support of the laser absorption spectrometer (LAS) remote sensor. These measurements were designed to provide comparative O3 data for the LAS sensor. The LAS, which was flown on a second aircraft, remotely measured the vertical burden of O3 from the aircraft to the surface. In situ results of the air quality (O3 and B sub scat) and meteorological (temperature and dewpoint) parameters for three correlative missions are presented. The aircraft flight plans, in situ concentration profiles and vertical burdens, and measurement errors are summarized

Contribution of ephemeral wetlands to annual nitrous oxide flux from an agricultural landscape

Non-Peer ReviewedMeasurement of soil nitrous oxide emissions from soil in the Canadian Prairie Region rarely includes uncultivated ephemeral wetlands (UW) within agricultural landscapes. Accurate inventories and a better understanding spatial and temporal variability for soil N2O in agricultural terrains requires flux measurements from non-agricultural areas of the field. The purpose of this study was to measure soil nitrous oxide flux from an agricultural landscape that includes UW. Measurements were taken weekly and bi-weekly from July to October of 2003 and from March to October of 2004 and 2005. Cumulative emissions were highest from concave elements (cultivated ephemeral wetlands) (CV) elements in 2003 and 2004 and highest from the basin centers (BC) of UW in 2005. High flux events were associated with rainfall in 2003, and the recession of standing water at CV and BC elements in 2004 and 2005. However, there are differences between ephemeral wetlands in their emission response to water recession. Accounting for aerial extent of landscape units reveals that CV elements make greatest contribution to total yearly flux. Beneficial management practices intended to reduce annual emissions from this site should be designed to reduce emission from CV elements and UW should not be cleared for crop production. Sampling designs for measurement of emissions from UW need not distinguish between riparian grass and riparian tree elements within the UW

Comparison of 32-site exact diagonalization results and ARPES spectral functions for the AFM insulator Sr2CuO2Cl2Sr_2CuO_2Cl_2

We explore the success of various versions of the one-band t-J model in explaining the full spectral functions found in angle-resolved photoemission spectra for the prototypical, quasi two-dimensional, tetragonal, antiferromagnetic insulator $Sr_2CuO_2Cl_2$. After presenting arguments justifying our extraction of $A(k,\omega)$ from the experimental data, we rely on exact-diagonalization results from studies of a square 32-site lattice, the largest cluster for which such information is presently available, to perform this comparison. Our work leads us to believe that (i) a one-band model that includes hopping out to third-nearest neighbours, as well three-site, spin-dependent hopping, can indeed explain not only the dispersion relation, but also the quasiparticle lifetimes -- only in the neighbourhood of $k = (\pi/2,0)$ do we find disagreement; (ii) an energy-dependent broadening function, $\Gamma (E) = \Gamma_0 + A E$, is important in accounting for the incoherent contributions to the spectral functions.Comment: 8 pages, Revtex