10,212 research outputs found

    Extending Invitations, Becoming Messmates

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    As music educators we can model proactive advocacy among community members to prevent individuals\u27 reactive violence in response to intolerance for differences. We can offer music-learning tables as safe spaces in which community members openly and collaboratively learn to know each other as individuals with diverse identities and interests. As messmates around the table, we can identify ways that researching, questioning, and being musical together can eradicate fears and the damaging effects of homophobia

    Tropospheric sulfate distribution during SUCCESS: Contributions from jet exhaust and surface sources

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    The distribution of SO4= aerosol over the central US during SUCCESS indicates that surface sources of SO4= and SO2 in the western US caused SO4= enhancements up to 10 km altitude. The mean (median) SO4= mixing ratio in the mid- and upper-troposphere increased from 24 (16) pptv over the Pacific ocean to 58 (29) pptv over the central plains. Above 10 km the SO4=mixing ratio was essentially the same in both regions, and also when the geographic classifications were further partitioned into upper tropospheric and lower stratospheric categories (mean near 40 pptv). No obvious enhancements of SO4= could be detected in jet exhaust plumes, but this may reflect the difficulty of keeping a large airborne sampling platform within a turbulent wake for time periods longer than a few seconds. Expected SO4=enhancements (based on observed CO2 enhancements and emission factors for these two species) were generally much smaller than the variability of ambient SO4= mixing ratios, so our null result does not mean that aircraft do not emit H2SO4

    Influence of vertical transport on free tropospheric aerosols over the central USA in springtime

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    Measurements of the atmospheric aerosol chemical composition during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) indicate substantial vertical transport of boundary layer aerosol to the free troposphere over the south-central United States during springtime. Mixing ratios of water-soluble aerosol Ca 2+ at 6 - 12 km altitude exhibited a median mixing ratio of 20 pptv, with 15% of the measurements \u3e 100 pptv and a maximum of ! 235 pptv. In air parcels with enhanced Ca 2+, the ratios K+/Ca 2+, Mg2+/Ca 2+, and Na+/Ca 2+ in the bulk aerosol were distinctly characteristic of those in limestone and/or cement. Significantly enhanced mixing ratios of aerosol SO42-, NO3-, and NH4 + were also concomitant with the elevated Ca 2+, suggesting transport of both crustal and anthropogenic aerosols to the upper troposphere. The mass concentration of water-soluble aerosol material was in the range 0.1 - 6 pg m -3 STP, and estimated crustal dust levels were 7 - 160 pg m \u273 ST

    Soluble acidic species in air and snow at Summit, Greenland

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    Simultaneous measurements of the concentrations of soluble acidic species in the gas, aerosol and snow phases at Summit, Greenland were made during summer 1993. Mean concentrations of gas phase HCOOH, CH3COOH, and HNO3 (49±28, 32±17 and 0.9±0.6 nmol m−3 STP, respectively) exceeded the concentrations of aerosol-associated HCOO−, CH3COO−, and NO3−by 1–3 orders of magnitude. On average, SO2 concentrations (0.9±0.6 nmol m−3 STP) were approximately 1/3 those of aerosol SO4=, but this ratio varied widely due largely to changes in the concentration of aerosol SO4=. Concentrations of aerosol SO4= plus SO2 consistently exceeded the sum of aerosol NO3− plus HNO3, yet NO3− was 3–20 times as abundant as SO4=in surface snow. Gas phase concentrations of HCOOH and CH3COOH at Summit were unexpectedly as large as those previously reported for several high latitude continental sites. However, carboxylate concentrations in snow were lower than those of SO4=. Our observation of post-depositional loss of these carboxylic acids within hours after a snowfall must partially explain the low concentrations found in snow. The relative abundance of soluble acids in summer snow at Summit was opposite of that in the overlying atmosphere. Our results highlight the need for improved understanding of the processes controlling transfer of soluble atmospheric species between air and snow

    Research opportunities on immunocompetence in space

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    The most significant of the available data on the effects of space flight on immunocompetences and the potential operational and clinical significance of reported changes are as follows: (1) reduced postflight blastogenic response of peripheral lymphocytes from space crew members; (2) postflight neutrophilia persisting up to 7 days; (3) gingival inflammation of the Skylab astronauts; (4) postflight lymphocytopenia, eosinopenia, and monocytopenia; (5) modifications and shifts in the microflora of space crews and spacecraft; and (6) microbial contamination of cabin air and drinking water. These responses and data disclose numerous gaps in the knowledge that is essential for an adequate understanding of space-related changes in immunocompetence

    Research opportunities in muscle atrophy

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    A trophy of skeletal muscle; muscle a trophy associated with manned space flight; the nature, causes, and mechanisms of muscle atrophy associated with space flight, selected physiological factors, biochemical aspects, and countermeasures are addressed

    Research opportunities in muscle atrophy

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    Muscle atrophy in a weightless environment is studied. Topics of investigation include physiological factors of muscle atrophy in space flight, biochemistry, countermeasures, modelling of atrophied muscle tissue, and various methods of measurement of muscle strength and endurance. A review of the current literature and suggestions for future research are included

    Research opportunities in loss of red blood cell mass in space flight

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    Decreases of red blood cell mass and plasma volume have been observed consistently following manned space flights. Losses of red cell mass by United States astronauts have averaged 10 to 15% (range: 2 to 21%). Based on postflight estimates of total hemoglobin, Soviet cosmonauts engaged in space missions lasting from 1 to 7 months have exhibited somewhat greater losses. Restoration of red cell mass requires from 4 to 6 weeks following return to Earth, regardless of the duration of space flight

    Real Estate Equity Investments and the Institutional Lender: Nothing Ventured, Nothing Gained

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    We consider a setup in which the channel from Alice to Bob is less noisy than the channel from Eve to Bob. We show that there exist encoding and decoding which accomplish error correction and authentication simultaneously; that is, Bob is able to correctly decode a message coming from Alice and reject a message coming from Eve with high probability. The system does not require any secret key shared between Alice and Bob, provides information theoretic security, and can safely be composed with other protocols in an arbitrary context
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