95 research outputs found
USE OF DREDGED MATERIAL TO CONSTRUCT WINTER WHOOPING CRANE HABITAT
Aransas National Wildlife Refuge (ANWR) and nearby coastal marshes serve as the winter home for the only natural flock of whooping cranes (Grus americana), In recent years shoreline erosion and the subsequent loss of wintering habitat have been observed on the refuge adjacent to the GulfIntracoastal Waterway (GIWW). In 1988 the U.S. Army Corps of Engineers (USACE) District, Galveston, Texas, and U.S. Fish and Wildlife Service (USFWS) entered into an informal agreement to attempt to slow shoreline/habitat loss on the refuge. Efforts to curtail habitat loss have included armoring the most erosive reaches with temporary concrete erosion control structures and using articulated concrete mats to armor severely eroded reaches. Most recent efforts have been directed at determining if dredged material removed from the GIWW during routine channel maintenance could be used to construct winter crane habitat. One experimental site was constructed in 1991 by Mitchell Energy Corporation and 2 in 1993 by USACE. Current plans call for the long-term monitoring of the sites to determine the relative success of the habitat creation effort. A comprehensive biomonitoring program is being developed by researchers at the USACE Waterways Experiment Station (WES) to track the long-term development and to characterize habitat conditions and wildlife use of the experimental sites
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Patterns in the occupancy and abundance of the globally rare lichen Erioderma pedicellatum in Denali National Park and Preserve, Alaska
We investigated habitat attributes related to the occupancy of the globally rare and endangered
epiphytic lichen, Erioderma pedicellatum, in a newly discovered (2009) population center in Denali National
Park and Preserve (DNPP), Alaska. We measured forest, tree and epiphytic lichen community
characteristics on eighty-five systematically selected plots in four study areas. We aggregated these data
at three spatial scales (tree, plot and study area) at which to compare E. pedicellatum occupancy (probability
of occurrence) and abundance to environmental covariates. We observed 2,035 E. pedicellatum thalli on 278
individual Picea glauca stems. The species occurred in 61% of the plots measured. Occupancy of E.
pedicellatum at the individual tree-scale was influenced by stem diameter, study area, live crown length, plot
P. glauca basal area, plot canopy cover and distance to open water. Our models for E. pedicellatum
occupancy at the plot-scale identified study area, P. glauca density, deciduous basal area (Betula neoalaskana
and Populus trichocarpa), and tall shrub cover ($ 200 cm in height) as significant covariates. Our estimates
of the DNPP population size increase the world population by at least tenfold to approximately 100,000
thalli. We suggest important topics for further research on E. pedicellatum.Keywords: Cyanolichens, Boreal forest, Pannariaceae, Habitat model, Logistic regressio
14-3-3 transits to the nucleus and participates in dynamic nucleocytoplasmic transport
14-3-3 proteins regulate the cell cycle and prevent apoptosis by controlling the nuclear and cytoplasmic distribution of signaling molecules with which they interact. Although the majority of 14-3-3 molecules are present in the cytoplasm, we show here that in the absence of bound ligands 14-3-3 homes to the nucleus. We demonstrate that phosphorylation of one important 14-3-3 binding molecule, the transcription factor FKHRL1, at the 14-3-3 binding site occurs within the nucleus immediately before FKHRL1 relocalization to the cytoplasm. We show that the leucine-rich region within the COOH-terminal α-helix of 14-3-3, which had been proposed to function as a nuclear export signal (NES), instead functions globally in ligand binding and does not directly mediate nuclear transport. Efficient nuclear export of FKHRL1 requires both intrinsic NES sequences within FKHRL1 and phosphorylation/14-3-3 binding. Finally, we present evidence that phosphorylation/14-3-3 binding may also prevent FKHRL1 nuclear reimport. These results indicate that 14-3-3 can mediate the relocalization of nuclear ligands by several mechanisms that ensure complete sequestration of the bound 14-3-3 complex in the cytoplasm
Testing and modeling of a traditional timber mortise and tenon joint
The structural safety and behaviour of traditional timber structures depends significantly on the performance of their connections. The behaviour of a traditional mortise and tenon timber joint is addressed using physical testing of full-scale specimens. New chestnut wood and old chestnut wood obtained from structural elements belonging to ancient buildings is used. In addition, the performance of different semi and non-destructive techniques for assessing global strength is also evaluated. For this purpose, ultrasonic testing, micro-drilling and surface penetration are considered, and the possibility of their application is discussed based on the application of simple linear regression models. Finally, nonlinear finite element analysis is used to better understand the behaviour observed in the full-scale experiments, in terms of failure mode and ultimate load. The results
show that the ultrasonic pulse velocity through the joint provides a reasonable estimate for the effective-
ness of the assembly between the rafter and brace and novel linear regressions are proposed. The failure mechanism and loadâdisplacement diagrams observed in the experiments are well captured by the proposed non-linear finite element analysis, and the parameters that affect mostly the ultimate load of the timber joint
are the compressive strength of wood perpendicular to the grain and the normal stiffness of the interface elements representing the contact between rafter and brace
Value-added strategies and forward integration in the Swedish sawmill industry: positioning and profitability in the high-volume segment
Aerial Census Techniques for Whooping Cranes on the Texas Coast
The U.S. Fish and Wildlife Service, using aerial surveys, regularly monitors the whooping crane (Grus americana) population wintering along the Texas coast. These regular census flights began in 1950 and have produced a long-term data set on the growth of a small population of endangered birds. This paper describes the specific methodology used by the authors during census flights
Einige Mittellungen ĂŒber den Vulkanologischen Dienst in NiederlĂ€ndisch-Indien und seine Arbeiten
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