9,571 research outputs found
Evaluation of Potential Translocation Sites for an Imperiled Cyprinid, the Hornyhead Chub
Translocation of isolated species into suitable habitats may help to secure vulnerable, geographically limited species. Due to the decline of Wyoming Hornyhead Chub Nocomis biguttatus, conservation actions, such as the translocation of populations within the plausible historical range, are being considered to improve population redundancy and resiliency to disturbance events. Translocation of Wyoming Hornyhead Chub must be rigorously evaluated because a hatchery stock does not exist, so all fish used in translocations will come from the wild population. We present an approach to identify the best available translocation sites prior to translocation efforts taking place. We evaluated fish community composition and habitat conditions at 54 potential translocation sites for Hornyhead Chub within 12 streams of the North Platte River basin of Wyoming. We used two analyses to identify translocation sites that were most similar to currently occupied Hornyhead Chub sites on the Laramie River: hurdle models to predict hypothetical abundance of Hornyhead Chub at translocation sites and nonmetric multidimensional scaling with fish community and habitat conditions. Presence and abundance of Hornyhead Chub were positively related to a lack of nonnative predators and to habitat features characteristic of backwater and velocity refuge habitats (e.g., minimum water velocity and width-to-depth ratio). We used a rank scoring system to weight the outcomes of each analysis, and the highest-ranking translocation sites occurred at a historically occupied locality, the Sweetwater River. Our approach may be appropriate for other at-risk species with isolated distributions and little historical data
Efficient solutions to the Euler equations for supersonic flow with embedded subsonic regions
A line Gauss-Seidel (LGS) relaxation algorithm in conjunction with a one-parameter family of upwind discretizations of the Euler equations in two dimensions is described. Convergence of the basic algorithm to the steady state is quadratic for fully supersonic flows and is linear for other flows. This is in contrast to the block alternating direction implicit methods (either central or upwind differenced) and the upwind biased relaxation schemes, all of which converge linearly, independent of the flow regime. Moreover, the algorithm presented herein is easily coupled with methods to detect regions of subsonic flow embedded in supersonic flow. This allows marching by lines in the supersonic regions, converging each line quadratically, and iterating in the subsonic regions, and yields a very efficient iteration strategy. Numerical results are presented for two-dimensional supersonic and transonic flows containing oblique and normal shock waves which confirm the efficiency of the iteration strategy
Some path-following techniques for solution of nonlinear equations and comparison with parametric differentiation
Some path-following techniques are described and compared with other methods. Use of multipurpose techniques that can be used at more than one stage of the path-following computation results in a system that is relatively simple to understand, program, and use. Comparison of path-following methods with the method of parametric differentiation reveals definite advantages for the path-following methods. The fact that parametric differentiation has found a broader range of applications indicates that path-following methods have been underutilized
Convection and heat transfer in layered sloping warm-water\ud aquifers
What convective flow is induced if a geologically-tratified groundwater aquifer is subject to a vertical temperature gradient? How strong is the flow? What is the nett heat transfer? Is the flow stable? How does the convection affect the subsequent species distribution if a pollutant finds its way into the aquifer? This paper begins to address such questions. Quantitative models for buoyancy-driven fluid flow in long, sloping warm-water aquifers with both smoothly- and discretely-layered structures are formulated. The steady-state profiles are calculated for the temperature and for the fluid specific volume flux (Darcy velocity) parallel to the boundaries in a sloping system subjected to a perpendicular temperature gradient, at low Rayleigh numbers. The conducted and advected heat fluxes are compared and it is shown that the system acts somewhat like a heat pipe. The maximum possible ratio of naturally advected-to-conducted heat transfer is determined, together with the corresponding permeability and thermal conductivity profiles
Archaeological Survey Investigations of Private Land within the boundaries of the proposed Lower Bois d’Arc Creek Reservoir Project, Fannin County, Texas
At the request of a private landowner that has property within the boundaries of the proposed Lower Bois d’Arc Creek Reservoir in Fannin County, we completed volunteer archaeological survey investigations on a portion of this tract of private land on July 18, 2015. The proposed Lower Bois d’Arc Creek Reservoir is to be more than 16,500 acres in size; the project sponsor is the North Texas Municipal Water District, and the Tulsa District of the U.S. Army Corps of Engineers is currently reviewing the project sponsor’s application for a Department of the Army permit under Section 404 of the Clean Water Act to construct the reservoir and associated facilities.
Although the project area associated with the proposed reservoir is more than 17,000 acres, only 5,000 acres of the proposed project have received an archaeological survey. Based on consultation between the project sponsor, the Texas Historical Commission, and the Tulsa District, the remainder of the project area will apparently not receive archaeological survey investigations. The private lands we have investigated along Bois d’Arc Creek in the proposed reservoir area have not been examined previously by a professional archaeological survey team; these lands will be inundated by the flood pool of the reservoir as currently proposed. The landowner had contacted the Tulsa District in 2008 to inform them that there were archaeological sites on the property, but the Tulsa District has yet to follow up on that information
The National Congress of Black Faculty
In recent years serious problems have arisen in the field of black higher education that have not been subject to systematic examination and corrective programming. These problems have magnified the necessity for a vehicle through which black faculty might be mobilized to contribute to the enhance ment of their own professional opportunities and thus make a significant impact upon black higher education in general. Some of these problems are discussed below
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