5,578 research outputs found
Measurement of trace stratospheric constituents with a balloon borne laser radar
The objective of this research was to measure the concentration of the stratospheric hydroxyl radical and related chemical species as a function of altitude, season, and time of day. Although hydroxyl plays a very important role in the chemistry controlling stratospheric ozone, little is known about its behavior because it has been a difficult species to measure. The instrument employed in this program was a laser radar, employing the technique of remote laser induced fluorescence. This instrument offers a number of attractive features including extreme specificity and sensitivity, a straightforward relationship between observed quantity and the desired concentration, and immunity to self-contamination
Laboratory spectroscopy in support of atmospheric measurements
Optical measurements of trace species in the atmosphere require precise, accurate spectroscopic data for the molecules under study. This laboratory exits to provide high quality spectroscopic data for the interpretation of data from existing satellite, balloon, ground, and aircraft instruments, as well as to provide sufficient data to assess the feasibility of new instruments
Ground-based lidar measurements of stratospheric ozone. The NASA/GSFC stratospheric ozone lidar trailer experiment STROZ LITE
The major research objective is the measurement of high precision vertical profiles of ozone between 20-40 kilometers. The precision is such that the instrument should be capable of detecting a small trend (on the order of less that 1 percent per year) over a 5-10 year period. Temperature was measured between 30 and 365 km. The Goddard Space Flight Center (GSFC) mobile lidar was installed at Table Mountain and a comparison between it and the permanent Jet Propulsion Laboratory (JPL) lidar was made over the course of about 3 weeks. The lidars agreed very well between 20 and 40 km, and under certain conditions up to 45-47 km. There were several anomalies that both lidars followed very well. Agreement with Rocket Ozonesonde (ROCOZ) and electrochemical concentration cell (ECC) sondes was also very good
The Stellar Content of Obscured Galactic Giant H II Regions IV.: NGC3576
We present deep, high angular resolution near-infrared images of the obscured
Galactic Giant H II region NGC3576. Our images reach objects to ~3M_sun. We
collected high signal-to-noise K-band spectra of eight of the brightest
objects, some of which are affected by excess emission and some which follow a
normal interstellar reddening law. None of them displayed photospheric features
typical of massive OB type stars. This indicates that they are still enshrouded
in their natal cocoons. The K-band brightest source (NGC3576 #48) shows CO 2.3
micron bandhead emission, and three others have the same CO feature in
absorption. Three sources display spatially unresolved H_2 emission, suggesting
dense shocked regions close to the stars. We conclude that the remarkable
object NGC3576 #48 is an early-B/late-O star surrounded by a thick
circumstellar disk. A number of other relatively bright cluster members also
display excess emission in the K-band, indicative of reprocessing disks around
massive stars (YSOs). Such emission appears common in other Galactic Giant H II
regions we have surveyed. The IMF slope of the cluster, Gamma = -1.51, is
consistent with Salpeter's distribution and similar to what has been observed
in the Magellanic Cloud clusters and in the periphery of our Galaxy.Comment: 14 pages, 11 figures, accepted for publication in A
CHEM2D-OPP: A new linearized gas-phase ozone photochemistry parameterization for high-altitude NWP and climate models
The new CHEM2D-Ozone Photochemistry Parameterization (CHEM2D-OPP) for high-altitude numerical weather prediction (NWP) systems and climate models specifies the net ozone photochemical tendency and its sensitivity to changes in ozone mixing ratio, temperature and overhead ozone column based on calculations from the CHEM2D interactive middle atmospheric photochemical transport model. We evaluate CHEM2D-OPP performance using both short-term (6-day) and long-term (1-year) stratospheric ozone simulations with the prototype high-altitude NOGAPS-ALPHA forecast model. An inter-comparison of NOGAPS-ALPHA 6-day ozone hindcasts for 7 February 2005 with ozone photochemistry parameterizations currently used in operational NWP systems shows that CHEM2D-OPP yields the best overall agreement with both individual Aura Microwave Limb Sounder ozone profile measurements and independent hemispheric (10°–90° N) ozone analysis fields. A 1-year free-running NOGAPS-ALPHA simulation using CHEM2D-OPP produces a realistic seasonal cycle in zonal mean ozone throughout the stratosphere. We find that the combination of a model cold temperature bias at high latitudes in winter and a warm bias in the CHEM2D-OPP temperature climatology can degrade the performance of the linearized ozone photochemistry parameterization over seasonal time scales despite the fact that the parameterized temperature dependence is weak in these regions
Spring Calving Suckler Beef Systems: Influence of Grassland Management System on Herbage Availability, Utilisation, Quality and Cow and Calf Performance to Weaning
Suckler beef systems in Ireland are primarily based on grass. Suckler systems vary in intensity but many operate low input systems and participate in REPS (Rural Environmental Protection Scheme). As there is a considerable cost associated with second-cut silage this research compared a two-cut system with a simplified low input one-cut system
HIV infection significantly reduces lipoprotein lipase which remains low after 6 months of antiretroviral therapy
Purpose of the study
Fractional clearance rate of apolipoprotein B100-containing
lipoproteins is reduced in HIV infection before and
after antiretroviral (ARV) treatment [1]. We compared
lipoprotein lipase (LPL) activity and gene expression in
HIV-positive subjects before and 6 months after ARV with
HIV-negative controls.
Methods
Fasting blood post heparin total and hepatic lipase activity,adiponectin, leptin, insulin, glucose, and lipid measurementswere made in 32 HIV-infected and 15 HIVnegative
controls. LPL was estimated by subtractinghepatic lipase from total lipase. Adiponectin, LPL andhormone sensitive lipase (HSL) gene expression weremeasured from iliac crest subcutaneous fat biopsies.Patients were tested before, and 6 months after randomisation to AZT/3TC (n = 15) or TDF/FTC (n = 17) with EFV.Between-group comparison was by Mann-Whitney andpaired samples by the Wilcoxon signed rank tests.
Summary of results
There were no differences in gender, ethnicity, baseline
BMI, regional fat distribution (whole body DEXA) and
visceral (VAT) and subcutaneous fat (SAT) measured by
abdominal CT scans between controls and patients. Trunk
fat/BMI ratio, VAT and VAT:SAT ratio significantly
increased after 6-month ARV therapy (p = 0.01). There
were no differences between groups in serum NEFA,HOMA and leptin levels. Selected other results are shown
in Table 1.
Conclusion
Post heparin lipoprotein lipase activity is reduced in HIV
and does not return to control levels after 6 months of
ARV therapy. AZT-containing regimens are associated
with a greater increase in LPL, LPL gene expression and
plasma adiponectin than TDF
TB195: Element Concentrations in Maine Forest Vegetation and Soils
Bioaccumulation of trace metals in plant tissues can present a health risk to wildlife, and potentially to humans. The Passamaquoddy Tribe in Maine was concerned about health risks of cadmium (Cd) because of a health advisory for moose liver and kidney consumption due to high Cd levels. In addition to Cd, this study evaluated concentrations of aluminum (Al), calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), nickel (Ni), phosphorus (P), lead (Pb), and zinc (Zn) in four common terrestrial moose-browse species, associated forest soils, and two species of aquatic vegetation on Passamaquoddy tribal land in eastern Maine. Elements were organized into three groups (A, B, and C) based on the patterns of concentration differences in vegetation among ecosystem types. Elements in group A included the nutrients Ca, K, Mg, and P and showed a pattern of significantly higher concentrations in hardwood and aquatic vegetation compared to softwoods. Group B elements included the four metals, Cd, Cu, Mn, and Zn, and exhibited a pattern of higher concentrations in hardwoods compared to softwoods and aquatic vegetation. Group C elements did not fit the patterns of group A or group B and included the remaining four elements Al, Fe, Ni, and Pb. Total O horizon soil concentration means for all elements, except Ni and Pb, were significantly higher in hardwood compared to softwood forest types. This study provides uncommon and important baseline vegetation and soil trace metal concentrations from a remote region in Maine of interest to environmental professionals.https://digitalcommons.library.umaine.edu/aes_techbulletin/1013/thumbnail.jp
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