The Emergent Properties of SSM in Use: A Symposium by Reflective Practitioners

Two careers, in industry and in university teaching at postgraduate level, have led to the development of Soft Systems Methodology (SSM) in a 30-year program of action research. The most cogent comments on SSM come from reflective practitioners, and in this symposium I have asked eight such users of SSM to reflect on their experience and to address the question of what it is that happens when the approach is used in real-world problem situations. Their responses reflect their different backgrounds, experience, and ways of working, but a broad general picture emerges. This suggests that SSM (whose process does not necessarily have to be made explicit to participants in a study) can engender a process of on-going (cyclic) coherent structured learning which feels natural, and which can surface previously unexamined assumptions, thus creating an arena in which accommodations can emerge which enable and motivate "action to improve" to be taken.     

Structural change and the combination of forecasts

Forecasters are generally concerned about the properties of model-based predictions in the presence of structural change. In this paper, it is argued that forecast errors can under those conditions be greatly reduced through systematic combination of forecasts. We propose various extensions of the standard regression-based theory of forecast combination. Rolling weighted least squares and time-varying parameter techniques are shown to be useful generalizations of the basic framework. Numerical examples, based on various types of structural change in the constituent forecasts, indicate that the potential reduction in forecast error variance through these methods is very significant. The adaptive nature of these updating procedures greatly enhances the effect of risk-spreading embodied in standard combination techniques.     

Dissociation between compensatory renal growth and induction of (Na++K+-ATPase in rat kidney after uninefrectomy

Zusammenfassung Nach Uninephrektomie und bilateraler Adrenalektomie entsteht eine Dissoziation zwischen der Nierenvergrösserung und der (Na⁺+K⁺)-ATPase Aktivität. Es besteht wahrscheinlich kein Zusammenhang zwischen der Nierenvergrösserung und der Induktion von (Na⁺+K⁺)-ATPase. Auch in der vergrösserten Niere sind die Nebennierenhormone notwendig, um die (Na⁺+K⁺)-ATPase zu erhalten.

---

---

The work was supported by a grant from P. Carl Petersen's Fund. Mrs.Birthe Bagge Hansen provided excellent technical assistance.     

Brain-state- and cell-type-specific firing of hippocampal interneurons in vivo

Neural-network oscillations at distinct frequencies have been implicated in the encoding, consolidation and retrieval of information in the hippocampus. Some GABA (gamma-aminobutyric acid)-containing interneurons fire phase-locked to theta oscillations (4-8 Hz) or to sharp-wave-associated ripple oscillations (120-200 Hz), which represent different behavioural states. Interneurons also entrain pyramidal cells in vitro. The large diversity of interneurons poses the question of whether they have specific roles in shaping distinct network activities in vivo. Here we report that three distinct interneuron types--basket, axo-axonic and oriens-lacunosum-moleculare cells--visualized and defined by synaptic connectivity as well as by neurochemical markers, contribute differentially to theta and ripple oscillations in anaesthetized rats. The firing patterns of individual cells of the same class are remarkably stereotyped and provide unique signatures for each class. We conclude that the diversity of interneurons, innervating distinct domains of pyramidal cells, emerged to coordinate the activity of pyramidal cells in a temporally distinct and brain-state-dependent manner.