Remarks on the layout of the subsonic free jet wind tunnels

By means of a recently installed wind tunnel with a circular free jet, it is shown that requirements concerning the flow parameters (e.g., uniform velocity profile and uniform and low turbulence level in the nozzle exit) can be easily and at moderate expenses fulfilled without changing the settling chamber and the nozzle itself. The installations in the settling chamber are adjustable. The structure is not limited to settling chambers with a circular cross section

Vertical and horizontal stability of streams in Northern Illinois

Includes bibliographical references.Includes illustrations and maps.Previous studies have shown that a number of streams in the midwest exhibit changes in channel geometry which are characteristic of stream disequilibrium. This study was undertaken to evaluate the equilibrium state of several streams in North Central Illinois, and to calculate the volume of sediment which results from the disequilibrium. Bridge blueprints and Soil Conservation Service (SCS) aerial photographs were used to document the vertical and horizontal locations of stream channels at various times since 1900. These known previous channel positions were then used as a datum against which to compare the present location of each. stream. Several conclusions were reached. 1) Streams from first to sixth order in North Central Illinois are currently degrading their channels at a rate of about 0.71 inches per year; they have been downcutting at approximately the same rate since at least 1900. 2) Concurrent downcutting and meandering produce a volume of sediment which is released downstream as pollution. The volume of pollution resulting from stream disequilibrium was found to be of the same order of magnitude as both the erosion losses reported by SCS, and the suspended sediment measured in regional streams by the USGS. The apparent causes of the disequilibrium are the changes in land use and changes in the natural drainage networks since European settlement.M.S. (Master of Science

Characterization of a lanfill-derived containment plume in glacial and bedrock aquifers, NE Illinois

Groundwater contamination by organic and inorganic chemicals is a regional and national problem; landfills are major potential contaminant sources. In this study of the Blackwell landfill, DuPage County, Illinois, the contaminant plume is delineated and related to the site history and hydrogeology. Leachate leakage is attributed partly to landfill construction problems. The landfill is located partly on a sand-and-gravel aquifer and partly on thick, poorly permeable till, all overlying an important dolomite aquifer. A roughly concentric contaminant plume surrounds the landfill in the glacial materials. A leachate leakage rate of between 600 and 3000 ft /day was estimated from infiltration and leachate-level calculations. The leakage is rapidly diluted in the aquifer; background TDS levels are reached on site. Volatile organics have concentrations of over 100 ppb in the aquifer close to the landfill, but decrease rapidly away. The contaminant plume appears to have reached equilibrium, and does not extend off site. The bedrock is probably in continuity with the glacial aquifer; however, the traces of organics found therein are not clearly linked to the landfill plume and may originate from other sources. This study has generated considerable field data which should be valuable in future studies.U.S. Department of the InteriorU.S. Geological Surve

Dietary cation–anion difference may explain why ammonium urate nephrolithiasis occurs more frequently in common bottlenose dolphins (\u3ci\u3eTursiops truncatus\u3c/i\u3e) under human care than in free-ranging common bottlenose dolphins

Ammonium urate nephrolithiasis frequently develops in common bottlenose dolphins (Tursiops truncatus) managed under human care but is rare in free-ranging common bottlenose dolphins. In other species, the dietary cation–anion difference (DCAD) can affect ammonium urate urolith forma- tion by increasing proton excretion as ammonium ions. Therefore, differences in diet between the 2 dolphin populations could affect urolith formation, but the DCAD of most species consumed by free-ranging and managed dolphins is unknown. To compare the nutrient composition of diets consumed by free-ranging and managed bottlenose dolphins, samples (n = 5) of the 8 species of fish commonly consumed by free-ranging bottlenose dolphins in Sarasota Bay, FL, and the 7 species of fish and squid commonly fed to man- aged bottlenose dolphins were analyzed for nutrient content. Metabolizable energy was calculated using Atwater factors; the DCAD was calculated using 4 equations commonly used in people and animals that use different absorption coefficients. The nutrient composition of individual species was used to predict the DCAD of 2 model diets typically fed to managed common bottlenose dolphins and a model diet typically consumed by common bottlenose dolphins in Sarasota Bay. To mimic differences in postmortem handling of fish for the 2 populations of bottlenose dolphins, “free-ranging” samples were immediately frozen at −80°C and minimally thawed before anal- ysis, whereas “managed” samples were frozen for 6 to 9 mo at −18°C and completely thawed. “Free- ranging” species contained more Ca and P and less Na and Cl than “managed” fish and squid species. As a consequence, the DCAD of both model managed dolphin diets obtained using 3 of the 4 equations was much more negative than the DCAD of the model free-ranging bottlenose dolphin diet (P \u3c 0.05). The results imply that managed bottlenose dolphins must excrete more protons in urine than free-ranging bottlenose dolphins, which will promote nephrolith formation. The nutrient composition of the free-ranging bottlenose dolphin diet, determined for the first time here, can be used as a guide for feeding managed bottlenose dolphins, but research in vivo is warranted to determine whether adding more cations to the diet will prevent urolith formation in managed dolphins

Dietary cation–anion difference may explain why ammonium urate nephrolithiasis occurs more frequently in common bottlenose dolphins (\u3ci\u3eTursiops truncatus\u3c/i\u3e) under human care than in free-ranging common bottlenose dolphins

Ammonium urate nephrolithiasis frequently develops in common bottlenose dolphins (Tursiops truncatus) managed under human care but is rare in free-ranging common bottlenose dolphins. In other species, the dietary cation–anion difference (DCAD) can affect ammonium urate urolith forma- tion by increasing proton excretion as ammonium ions. Therefore, differences in diet between the 2 dolphin populations could affect urolith formation, but the DCAD of most species consumed by free-ranging and managed dolphins is unknown. To compare the nutrient composition of diets consumed by free-ranging and managed bottlenose dolphins, samples (n = 5) of the 8 species of fish commonly consumed by free-ranging bottlenose dolphins in Sarasota Bay, FL, and the 7 species of fish and squid commonly fed to man- aged bottlenose dolphins were analyzed for nutrient content. Metabolizable energy was calculated using Atwater factors; the DCAD was calculated using 4 equations commonly used in people and animals that use different absorption coefficients. The nutrient composition of individual species was used to predict the DCAD of 2 model diets typically fed to managed common bottlenose dolphins and a model diet typically consumed by common bottlenose dolphins in Sarasota Bay. To mimic differences in postmortem handling of fish for the 2 populations of bottlenose dolphins, “free-ranging” samples were immediately frozen at −80°C and minimally thawed before anal- ysis, whereas “managed” samples were frozen for 6 to 9 mo at −18°C and completely thawed. “Free- ranging” species contained more Ca and P and less Na and Cl than “managed” fish and squid species. As a consequence, the DCAD of both model managed dolphin diets obtained using 3 of the 4 equations was much more negative than the DCAD of the model free-ranging bottlenose dolphin diet (P \u3c 0.05). The results imply that managed bottlenose dolphins must excrete more protons in urine than free-ranging bottlenose dolphins, which will promote nephrolith formation. The nutrient composition of the free-ranging bottlenose dolphin diet, determined for the first time here, can be used as a guide for feeding managed bottlenose dolphins, but research in vivo is warranted to determine whether adding more cations to the diet will prevent urolith formation in managed dolphins