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Report on effects of changing predation pressure on benthic and pelagic species

The room temperature fatigue properties of a semisolid cast A356 alloy have been defined by determining a Wšhler curve for lives between 104 and 107 cycles. The fatigue tests were carried out in axial tension/compression cycling at zero mean stress (stress ratio, R, of -1). The initiation sites of the fatigue cracks were studied in detail and it was observed that cracks generally initiated from shrinkage pores or oxide films at the surfaces of the machined fatigue specimens. Measurements of the sizes of these defects are reported, and evidence is presented to suggest that oxide defects have less effect on the fatigue life than shrinkage pores of the same size, presumably reflecting differences in the ease of fatigue crack initiation at the two types of defects. The fatigue properties of our particular semisolid castings are compared with those of casting made by other processes. It is shown that the semisolid castings performed slightly better than squeeze castings made in our laboratory using the same machine and the same die. The properties of both the semisolid and squeeze castings are significantly better than those of gravity diecastings.

The Fms-interacting protein (FMIP, MW 78 kDa) acts as a shuttling protein during macrophage differentiation in the human immune system.1

Both host carbogen (95% oxygen/5% carbon dioxide) breathing and nicotinamide administration enhance tumour radiotherapeutic response and are being re-evaluated in the clinic. Non-invasive magnetic resonance imaging (MRI) and 31P magnetic resonance spectroscopy (MRS) methods have been used to give information on the effects of nicotinamide alone and in combination with host carbogen breathing on transplanted rat GH3 prolactinomas. Gradient recalled echo (GRE) MRI, sensitive to blood oxygenation changes, and spin echo (SE) MRI, sensitive to perfusion/flow, showed large signal intensity increases with carbogen breathing. Nicotinamide, thought to act by suppressing the transient closure of small blood vessels that cause intermittent tumour hypoxia, induced a small increase in blood oxygenation but no detectable change in perfusion/flow. Carbogen combined with nicotinamide was no more effective than carbogen alone. Both carbogen and nicotinamide caused significant increases in the nucleoside triphosphate/inorganic phosphate (βNTP/P i) ratio, implying that the tumour cells normally receive sub-optimal substrate supply, and is consistent with either increased glycolysis and/or a switch to more oxidative metabolism. The most striking observation was the marked increase in blood glucose (twofold) induced by both nicotinamide and carbogen. Whether this may play a role in tumour radiosensitivity has yet to be determined. Copyright 2000 Cancer Research Campaign© 2000 Cancer Research Campaign

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