Cybernetics and suprahuman autopoietic systems

Several streams of cybernetic thinking lead to the notion that there may exist systems of a higher logical order than that of manmade organisation. Such systems would be autopoietic and, in principle, beyond human control. Man and his institutions would be but components of such systems. The accelerated growth of institutions and the connections between them facilitated by the IT revolution makes the realization of such systems more probable at this time. The implications for systems practice are discussed.     

David Hume and systems practice

The aim of this paper is to provide some refreshment for jaded and confused spirits. David Hume, the foremost critic of the Enlightenment, asked some questions, pertinent to systems practice, which have yet to be answered fully. His attacks on superstition and naive realism will be received with sympathy today, but he still makes challenges to rationalism and to a priori knowledge and principles, which are as fresh today as they were in his time. He also has some advice for systems practitioners.     

Carbohydrase and esterase activity in the gut of larvalCallosobruchus maculatus

Summary Carbohydrase activity has been demonstrated in homogenates of the alimentary tracts of late instar larvae ofC. maculatus:-D galactosidase, -D glucosidase and N-acetyl-D glucosaminidase activities were comparable and significantly greater than -D galactosidase,-D glucosidase and -D mannosidase. The effects of pH and substrate concentration are reported. The presence and changes in pattern of non-specific esterase activity in larval and adult gut homogenates is also described.     

Nickel solvent extraction from cold purification filter cakes of Angouran mine concentrate using LIX984N

Cold purification filter cakes generated in the hydrometallurgical processing of Angouran mine zinc concentrate commonly contain significant amounts of Zn, Cd, and Ni ions and thus are valuable resources for metal recovery. In this research, a nickel containing solution that was obtained from sulfuric acid leaching of the filter cake following cadmium and zinc removal was subjected to solvent extraction experiments using 10vol% LIX984N diluted in kerosene. Under optimum experimental conditions (pH 5.3, volume ratio of organic/aqueous (O:A) = 2:1, and contact time = 5 min), more than 97.1% of nickel was extracted. Nickel was stripped from the loaded organic by contacting with a 200 g/L sulfuric acid solution, from which 77.7% of nickel was recovered in a single contact at the optimum conditions (pH 1–1.5, O:A = 5:1, and contact time = 15 min).