4,306 research outputs found
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~ COMMUNICATIONSThis book originally was published by Peer-to-Peer Communications. It is out ofprint and the rights have reverted to the authors, who hereby place it in the public domain. Publisher's Cataloging-in-Publication (Provided by Quality Books, Inc.
A Simple Model for Finite Chemical Kinetics Analysis of Supersonic Turbulent Shear Layer Combustion
A simple flow/thermodynamic model is proposed
to describe finite chemical kinetic rate combustion
in a turbulent supersonic shear layer for the
purposes of assessing Damköhler number effects in
such flows. Sample calculations and comparisons
for the H_2/NO/F_2 chemical system and the H_2/air
system are described for a set of initial flow and
thermodynamic conditions of the entrained
reactants
Identification of Mullerian Chromosomal Elements in Hawaiian Drosophila by in situ DNA Hybridization
We have hybridized Drosophila melanogaster DNA sequences
to polytene chromosomes of D. silvestris. The results support Muller's hypothesis
that the chromosomal elements have been largely conserved in the evolution
of the genus Drosophila. As originally suggested by Carson, D. melanogaster
elements X, 2L, 2R, 3L, and 3R appear to correspond to chromosomes X, 3, 2,
5, and 4, respectively, in D. silvestris and the Hawaiian picture-winged species
Limitations in Predicting Radiation-Induced Pharmaceutical Instability during Long-Duration Spaceflight
As human spaceflight seeks to expand beyond low-Earth orbit, NASA and its
international partners face numerous challenges related to ensuring the safety
of their astronauts, including the need to provide a safe and effective
pharmacy for long-duration spaceflight. Historical missions have relied upon
frequent resupply of onboard pharmaceuticals; as a result, there has been
little study into the effects of long-term exposure of pharmaceuticals to the
space environment. Of particular concern are the long-term effects of space
radiation on drug stability, especially as missions venture away from the
protective proximity of the Earth. Here we highlight the risk of space
radiation to pharmaceuticals during exploration spaceflight, identifying the
limitations of current understanding. We further seek to identify ways in which
these limitations could be addressed through dedicated research efforts aimed
towards the rapid development of an effective pharmacy for future spaceflight
endeavors.Comment: in press, Nature Microgravit
The Influence of Fetch on the Holocene Thermal Structure of Hidden Lake, Glacier National Park
We use three-dimensional modeling of the basin of Hidden Lake, Montana, to assess the influence of effective fetch on diatom-inferred changes in mixing depths throughout the Holocene. The basin of Hidden Lake is characterized by a complex morphometry; for example, three-dimensional modeling of the lake basin indicates that a decrease in lake level of 2 m would result in complete isolation of the deepest part of the lake basin from the rest of the lake. Our model suggests that small changes in the lake surface elevation at Hidden Lake would produce threshold-like responses in effective fetch, which in turn would have a profound influence on average lake mixing depth. The present-day planktic diatom community of Hidden Lake is comprised of three species. Neo-ecological experiments revealed the effect of mixing depth and nutrient levels on growth rates of these species. A sediment core collected from the deepest part of the lake basin and spanning the last 8,640 years was analyzed for diatoms. Here we show how changes in fetch through the Holocene explain changes in the dominant planktic diatom species by modification of the thermal structure of Hidden Lake. Additionally, the timing of diatominferred changes in effective moisture and thermal structure from Hidden Lake were compared to late Holocene patterns reconstructed from other regional lake records. Between 8.64 – 7.61 ka the diatom record from Hidden Lake suggests that the lake was deep and fresh, although somewhat lower than the modern lake. After 7.61 ka, water levels rose, expanding the available benthic diatom habitat. Between 6.18 and 4.13 ka, lake level declined and seasonal stratification was enhanced. After 1.4 ka, the lake became deeper and less stratified in response to the effects of enhanced fetch. We argue that changes in effective fetch may play an important, and underexplored, role in planktic diatom community structure over longer time scales and should be more broadly considered in paleolimnological studies
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