6,465 research outputs found

    Aquatic Ecosystem Response to Storm Water Abatement Measures in the Ravines of the GVSU Allendale Campus: Establishment of Base-line Biological Condition

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    The ravine tributary streams surrounding Grand Valley State Universities Allendale campus represent unique and understudied ecosystems, worthy of significant restoration efforts and of long-lasting protection. They are variously affected by storm water runoff, representing a spectrum from severely impacted to relatively pristine. Quantitative macroinvertebrate samples taken from six streams in late June 2007, indicated that insect diversity was positively correlated to ammonium (p=0.057), while total abundance was negatively correlated to phosphate and chlorophyll-a concentration (n.s.). In addition, phosphate, nitrate, sulfate and iron concentrations were elevated in streams that experience significant storm-water runoff and these streams also tended to have lower macroinvertebrate abundance, diversity and richness. These elevated nutrients, phosphorus in particular, were rapidly taken up by the benthic algae as evidenced by declining nutrients, and increased algal pigment and organic matter concentration from up to down-stream (n.s.). Biological uptake did not translate into increased macroinvertebrate abundance, likely because of the flashy discharge regime. Combination of non EPT (Ephemeroptera, Plecoptera, and Trichoptera) metrics indicated that the Shire and Junkyard ravines were in better condition than sites at Isengard and Fangorn—patterns which strongly suggest that extent of storm-water runoff has negatively impacted the macroinvertebrate communities. The fish community assessment indicated that blacknose dace (Rhinichthys atratulus), a species known to prefer cold, clean water, was most abundant in the Shire—the most pristine ravine stream sampled. Comparing length/weight data in the sampled streams to state standards indicated that these dace are not as fit as typically found in other water bodies whereas other taxa, namely the white sucker (Catostomus commersonii) and creek chub (Somotillus atromaculatus) are indistinguishable from state fitness standards. We were successful establishing biological base-line conditions prior to the initiation of a campus wide storm-water abatement program and can use these benchmarks to gage the long-term efficacy of restoration using physicochemical, population, community and ecosystem functional attributes measured in these unique ecosystems

    Texas-Oklahoma Producer Cotton Market Summary: 2000/2001

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    The size of the Texas-Oklahoma spot market analyzed by the Daily Price Estimation System (DPES) for the 2000/2001 marketing year decreased considerably from the previous year. The average price received by producers during the 2000/2001 marketing year was about 50.9 cents/lb. The 2000 crop was generally of good quality, but the averages for the first digit of the color grade and leaf grade detoriated as compared with the 1999 crop. The percentage of bales having level 1 and 2 bark, and level 1 and 2 other extraneous matter decreased in comparison to the 1999 crop. With the exception of the second digit of the color grade price discounts for the 2000 crop decreased for all quality attributes. The premiums for the first digit of the color grade and strength both decreased, while the premium for leaf increased and that of staple remained about the same.Crop Production/Industries,

    Eurasian watermilfoil biomass associated with insect herbivores in New York

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    A study of aquatic plant biomass within Cayuga Lake, New York spans twelve years from 1987-1998. The exotic Eurasian watermilfoil ( Myriophyllum spicatum L.) decreased in the northwest end of the lake from 55% of the total biomass in 1987 to 0.4% in 1998 and within the southwest end from 50% in 1987 to 11% in 1998. Concurrent with the watermilfoil decline was the resurgence of native species of submersed macrophytes. During this time we recorded for the first time in Cayuga Lake two herbivorous insect species: the aquatic moth Acentria ephemerella , first observed in 1991, and the aquatic weevil Euhrychiopsis lecontei , first found in 1996 . Densities of Acentria in southwest Cayuga Lake averaged 1.04 individuals per apical meristem of Eurasian watermilfoil for the three-year period 1996-1998. These same meristems had Euhrychiopsis densities on average of only 0.02 individuals per apical meristem over the same three-year period. A comparison of herbivore densities and lake sizes from five lakes in 1997 shows that Acentria densities correlate positively with lake surface area and mean depth, while Euhrychiopsis densities correlate negatively with lake surface area and mean depth. In these five lakes, Acentria densities correlate negatively with percent composition and dry mass of watermilfoil. However, Euhrychiopsis densities correlate positively with percent composition and dry mass of watermilfoil. Finally, Acentria densities correlate negatively with Euhrychiopsis densities suggesting interspecific competition

    Systematic Mischaracterization of Exoplanetary System Dynamical Histories from a Model Degeneracy near Mean-motion Resonance

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    There is a degeneracy in the radial velocity exoplanet signal between a single planet on an eccentric orbit and a two-planet system with a period ratio of 2:1. This degeneracy could lead to misunderstandings of the dynamical histories of planetary systems as well as measurements of planetary abundances if the correct architecture is not established. We constrain the rate of mischaracterization by analysing a sample of 60 non-transiting, radial velocity systems orbiting main-sequence stars from the NASA Exoplanet Archive (NASA Archive) using a new Bayesian model comparison pipeline. We find that 15 systems (25 per cent of our sample) show compelling evidence for the two-planet case with a confidence level of 95 per cent

    ECLSS Reliability for Long Duration Missions Beyond Lower Earth Orbit

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    Reliability has been highlighted by NASA as critical to future human space exploration particularly in the area of environmental controls and life support systems. The Advanced Exploration Systems (AES) projects have been encouraged to pursue higher reliability components and systems as part of technology development plans. However, there is no consensus on what is meant by improving on reliability; nor on how to assess reliability within the AES projects. This became apparent when trying to assess reliability as one of several figures of merit for a regenerable water architecture trade study. In the Spring of 2013, the AES Water Recovery Project (WRP) hosted a series of events at the NASA Johnson Space Center (JSC) with the intended goal of establishing a common language and understanding of our reliability goals and equipping the projects with acceptable means of assessing our respective systems. This campaign included an educational series in which experts from across the agency and academia provided information on terminology, tools and techniques associated with evaluating and designing for system reliability. The campaign culminated in a workshop at JSC with members of the ECLSS and AES communities with the goal of developing a consensus on what reliability means to AES and identifying methods for assessing our low to mid-technology readiness level (TRL) technologies for reliability. This paper details the results of the workshop

    Isomolybdate conversion coatings

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    A conversion coating solution and process forms a stable and corrosion-resistant layer on metal substrates or layers or, more preferably, on a boehmite layer or other base conversion coating. The conversion coating process involves contacting the substrate, layer or coating with an aqueous alkali metal isomolybdate solution in order to convert the surface of the substrate, layer or coating to a stable conversion coating. The aqueous alkali metal molybdates are selected from sodium molybdate (Na.sub.2 MoO.sub.4), lithium molybdate (Li.sub.2 MoO.sub.4), potassium molybdate (K.sub.2 MoO.sub.4), or combinations thereof, with the most preferred alkali metal molybdate being sodium molybdate. The concentration of alkali metal molybdates in the solution is preferably less than 5% by weight. In addition to the alkali metal molybdates, the conversion coating solution may include alkaline metal passivators selected from lithium nitrate (LiNO.sub.3), sodium nitrate (NaNO.sub.3), ammonia nitrate (NH.sub.4 NO.sub.3), and combinations thereof; lithium chloride, potassium hexafluorozirconate (K.sub.2 ZrF.sub.6) or potassium hexafluorotitanate (K.sub.2 TiF.sub.6)
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