Restoration of a brown trout (Salmo trutta L.) population to Loch Enoch, an acified Loch in Galloway, South-West Scotland

The authors present the findings of a restoration project in Loch Enoch in Scotland. There are historical references that brown trout was present in Loch Enoch up to the 1920s but it is believed the acidity of loch triggered the disappearance of Salmo trutta. The recent observed reduction in the acidity of L. Enoch to a level close to that found in nearby lochs with trout populations, suggested that trout might now survive in L. Enoch. For a population to survive, all stages in the life-cycle of a species must be able to develop. Accordingly, tests were undertaken, first with eggs and fry. The availability of food was also studied. In October 1994, 3,000 yearling trout of L. Grannoch origin which had been reared in a local hatchery were distributed throughout the loch. The fish population was studied from 1995-98. The authors conclude that survival of the trout population is possible if the acidity of the loch water remains low

Experimental non-equilibrium radiation measurements for low-Earth orbit return

This paper reports on absolute radiation measurements performed in synthetic air (20.78% O2, 79.22% N2) shock-heated flows. Experiments were carried out in the Oxford T6 Stalker Tunnel in Aluminium Shock Tube mode. Data is presented for velocities ranging from 5.5-7.2 km/s at a nominal 1 bar post-shock pressure, in both UV/Vis and Vis/NIR spectral ranges. Simulations of the equilibrium radiance using NASA CEA and NEQAIR codes underpredict that obtained from the experimental data. An analysis using the newly developed LASTA code removes shock deceleration from consideration as a cause for this discrepancy. Non-equilibrium data is analysed in the form of spectral and absolute non-equilibrium metrics, and the effects of shock speed and post-shock pressure on the non-equilibrium radiance isolated. Finite-rate one-dimensional two-temperature simulations using POSHAX3 with Park 1993 rates are performed, which significantly underpredict the experimentally acquired data

Radiation measurements of shockwaves in synthetic air and pure nitrogen

Absolute radiance measurements in synthetic air and pure nitrogen have been performed in the Oxford T6 Stalker Tunnel while operating in Aluminium Shock Tube mode. Spatially and spectrally resolved data have been attained for shock speeds from 5.7 to 8 km/s and post-shock pressures from ∼10 to ∼100 kPa. Two independent telecentric optical set ups acquire data from the UV/Vis (200 to 520 nm) and Vis/NIR (585 to 850 nm) regions. The data are presented in multiple formats. An example 2D spectral-spatial map of absolute radiance is provided. Equilibrium spectral radiance comparisons against CEA-NEQAIR demonstrate improved agreement since prior campaigns in both T6 and the Electric Arc Shock Tube at NASA Ames. Spatial radiance profiles demonstrate lower pressure conditions can improve the resolution of non-equilibrium relaxation. Finally, spectral profiles progressing through the relaxation region for a low pressure synthetic air test case are shown. The motivation of this paper is to provide reliable calibrated data that, in future work, can be used to extract thermochemical rates and upon which numerical codes and facility results can be benchmarked against

Radiative heat transfer measurements of Titan atmospheric entry in a shock tube

Measurements were performed in the T6 Stalker facility operating in Aluminum Shock Tube mode for conditions relevant to Titan entry. Spatially and spectrally resolved radiation emitted from a high-temperature test gas behind a normal shock was recorded by means of emission spectroscopy. For Titan atmospheric entry, the main radiator of interest is cyano radical, formed in the nonequilibrium region behind the shock. The tests reported in this work measured radiation at velocities from 3.1 to 8.5 km/s and freestream pressures of 13, 20, and 133 Pa at a nominal composition of 98% N2 and 2% CH4. These shock layer radiation experiments employed an optical emission spectroscopy system on each side of the facility to allow two spectral regions to be measured simultaneously for each test, covering the spectral range of 200–900 nm. The present work provides a new, comprehensive benchmark set of data relevant to Titan entry studies

Commissioning of upgrades to T6 to study giant planet entry

The scientific potential of a mission to the ice giants is well recognized and has been identified by NASA and ESA as a high priority on several occasions, most recently in the 2023–2032 Decadal Survey. The payload capacity of such a spacecraft is limited by the heat shield thickness, which must be sized conservatively due to a lack of reliable data for convective and radiative heat flux along the proposed entry trajectories. Major upgrades to the Oxford T6 Stalker Tunnel have been commissioned that allow study of giant planet entry trajectories, including a flammable gas handling system, a Mach 10 expansion nozzle, and a steel shock tube with optical access. Initial testing has been completed in shock tube and expansion tunnel modes, with peak shock speeds of 18.9 km/s achieved. Convective heat flux and surface pressure were measured at several locations on a 45° sphere cone model in expansion tunnel mode. Measurements of the radiating shock layer were made in shock tube mode to assess the effect of CH4 concentration. This work establishes the first high-enthalpy giant planet entry test bed in Europe

Restoration of a brown trout (Salmo trutta L.) population to Loch Enoch, an acidified Loch in Galloway, south-west Scotland

The decline and, in some waters, the disappearance of brown trout Salmotrutta populations in south-west Scotland have been attributed to surface wateracidification (Harriman et al. 1987; Maitland et al. 1987). From changesin the diatom flora and levels of heavy metals in sediment cores, Flower et al.(1987) have calculated water quality changes over the past 200 years for lochsin this area. For Loch Enoch (Fig. 1, and front cover illustration) theyconcluded that the pH of the loch water had decreased from 5.4 around 1840,to 4.8 in c. 1930, then more rapidly to 4.4 in 1982

Reperfusion in acute myocardial infarction

Studies of the pathophysiology of acute myocardial infarction (AMI) have shown that in most pa- tients a thrombus forms over a ruptured ather- oma in the infarct-related coronary artery and obstructs the artery