444 research outputs found

    Quantifying Channel Responses to the Removal of the Glines Canyon Dam in the Middle Reach of the Elwha River, Washington

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    Four different study sites throughout the middle reach of the Elwha River were monitored before, during, and after the dam removal process over a period of two years from 2012-2014. The complexity of the river geometry was a major factor in the ability of the river to trap and accumulate the new influx of woody debris and sediment from the dam removal, which influenced the response of the river channel. The change that occurred was quantified by using repeat Terrestrial LiDAR (TLS), sediment distribution surveys, and large woody debris mapping techniques. The morphologic changes that occurred during this time were caused by multiple different geomorphic influences. The most notable was the initial sediment pulse that that inundated the downstream river channel in the first few months of the reservoir sediment release. In turn, it filled the riffles and pools throughout the entire middle reach of the river, and the subsequent deposition was channel geometry dependent. As the initial sediment wave dissipated and the river continued transport sediment from the Glines Canyon Dam, the channel geometry was still the major factor in woody debris collection and sediment deposition followed by river discharge. Woody debris anchored and accumulated on sediment bars throughout the entire middle reach; it became apparent that the more complex the channel system (i.e. multiple channels, vegetated islands, riffles and pools, or a sharp channel bend), the more likely the woody debris was to collect. Furthermore, as the woody debris deposited coalesced into log jams, it influenced the sediment deposition by armoring the banks of channels and creating areas of slow moving water. The combined deposition of sediment and woody debris caused areas of the channel to migrate, increasing the complexity of the river geometry. This study has provided some much-needed empirical data necessary to model future dam removal projects. It demonstrated that the use of TLS combined with surveys of large woody debris and sediment distribution can provide detailed information about the effects of the dam removal in different geomorphic settings

    Debt, financial stability, and public policy

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    Debt ; Economic policy ; Economic stabilization

    Archaeology of Atafu, Tokelau: Some initial results from 2008

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    Surface survey, shovel testing, and stratigraphic excavations were done on Atafu Atoll in Tokelau during August 2008. Initial results suggest that Fale Islet has the most potential for further archaeological research. Dense cultural deposits on this islet are >1 m (39 in.) deep. Cultural material recovered includes food bone, fire-affected volcanic rock, tool-grade basalt flakes and tool fragments, Tridacna shell adzes, and pearl-shell fishhook fragments. Dog bone occurs from the earliest deposits through to the late prehistoric, while pig bone is found only in historic contexts. Fish bone is common throughout, and, with the exception of Tridacna, there are few edible mollusk remains. Initial EDXRF (Energy Dispersive X-Ray Fluorescence) analyses have found the basalt to be consistent with documented sources on Tutuila, Samoa. Basal radiocarbon dates from two excavation units are 660-540 cal. BP and 500-310 cal. BP (at 2σ)

    Yeast Homologues of Three BLOC-1 Subunits Highlight KxDL Proteins As Conserved Interactors of BLOC-1.

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    Biogenesis of lysosome-related organelle complex-1 (BLOC-1) is one of the four multi-subunit complexes implicated in sorting cargo to lysosome-related organelles, as loss of function of any of these complexes causes Hermansky-Pudlak syndrome. Eight subunits of BLOC-1 interact with each other and with many other proteins. Identifying new interactors of BLOC-1 will increase understanding of its mechanism of action, and studies in model organisms are useful for finding such interactors. PSI-BLAST searches identify homologues in diverse model organisms, but there are significant gaps for BLOC-1, with none of its eight subunits found in Saccharomyces cerevisiae. Here we use more sensitive searches to identify distant homologues for three BLOC-1 subunits in S. cerevisiae: Blos1, snapin and cappuccino (cno). Published data on protein interactions show that in yeast these are likely to form a complex with three other proteins. One of these is the yeast homologue of the previously uncharacterized KxDL protein, which also interacts with Blos1 and cno in higher eukaryotes, suggesting that KxDL proteins are key interactors with BLOC-1

    Solar thermochemical production of ammonia from water, air and sunlight: Thermodynamic and economic analyses

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    Ammonia is an important input into agriculture and is used widely as base chemical for the chemical industry. It has recently been proposed as a sustainable transportation fuel and convenient one-way hydrogen carrier. Employing typical meteorological data for Palmdale, CA, solar energy is considered here as an inexpensive and renewable energy alternative in the synthesis of NH3 at ambient pressure and without natural gas. Thermodynamic process analysis shows that a molybdenum-based solar thermochemical NH3 production cycle, conducted at or below 1500 K, combined with solar thermochemical H2 production from water may operate at a net-efficiency ranging from 23 to 30% (lower heating value of NH3 relative to the total energy input). Net present value optimization indicates ecologically and economically sustainable NH3 synthesis at above about 160 tons NH3 per day, dependent primarily on heliostat costs (varied between 90 and 164 dollars/m2), NH3 yields (ranging from 13.9 mol% to stoichiometric conversion of fixed and reduced nitrogen to NH3), and the NH3 sales price. Economically feasible production at an optimum plant capacity near 900 tons NH3 per day is shown at relative conservative technical assumptions and at a reasonable NH3 sales price of about 534 ± 28 dollars per ton NH3
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