Tripod model

The TRIPOD model presents an accident model of causal sequences rather similar to the logic principles of the ILCI model, Figure 5.3 (Reason, 1991 Reason, 1997). It has had a large influence on current thinking, because it models how erroneous decisions at different management levels lead up to the circumstances of which the accident is a result. We will apply aspects from the TRIPOD model in Chapter 6. We will illustrate how accident occurrence is affected both by operational decisions at the work system level immediately before the accident, and by higher management decisions. 

In the TRIPOD model, a distinction is made between different classes of human failure, mainly coinciding with the levels of organisational hierarchy ... 

The TRIPOD model also helps us in understanding the relationship between... 

The TRIPOD model includes SHE culture elements (Reason, 1991). In an accident investigation, the model is used to classify top management commitment on a scale from 1 (pathological) to 7 (generative-proactive). We will treat this aspect of the TRIPOD model in more detail in Section 6.5. 

In the TRIPOD model, the underlying factors at the workplace or department level behind accidents are called latent failures. Based on research into accident causation, 11 different so-called General Failure Types have been identified (Wagenaar in Feyer and Williamson, 1998). They comprise... 

The TRIPOD model has another focus (Reason, 1990). Source-failure types relate to top-management commitment and competence and to accident perceptions and the safety culture at the company. A seven-point scale for the evaluation of top-management commitment is suggested ... 

Tripod-Beta is a third variant based on the Tripod model of Section 5.2 (Reason, 1997). The associated PC software makes it possible for the analyst to document the findings of the investigation and to produce a graphic incident tree with the immediate circumstances of the accident (hazards and barrier failures) and the underlying active and latent failures and preconditions. 

In order to construct new types of binding and activating models of dioxygen molecules, Jitsukawa, Masuda and their co-workers have synthesized a novel group of tripodal tetradentate ligands and successfully utilized them in the formation of mononuclear copper(II) complexes with novel structural features (complexes (473)-(488)).395-403 This group of ligands has four... 

Zinc is the active metal in the largest group of metalloproteins found in the nature. Recently a new class of zinc enzymes with a sulfur-rich environment has emerged the thiolate-alkylating enzimes, the most prominent of which is the cobalamine-independent methionine synthase.126 For these reasons several monothiolate zinc complexes have been prepared for the modelling of these enzymes with different N2S as (13),127 130 N20,13° 132 N3,132,133 S3,134 tripod ligands, or with Cd because of the favourable spectroscopic properties with an S3 tripod ligand.135... 

Tripodal N V,0-Ligands for Metalloenzyme Models and Organometallics Nicolai Burzlaff... 

Fe(III) displacement of Al(III), Ga(III), or In(III) from their respective complexes with these tripodal ligands, have been determined. The M(III)-by-Fe(III) displacement processes are controlled by the ease of dissociation of Al(III), Ga(III), or In(III) Fe(III) may in turn be displaced from these complexes by edta (removal from the two non-equivalent sites gives rise to an appropriate kinetic pattern) (343). Kinetics and mechanism of a catalytic chloride ion effect on the dissociation of model siderophore-hydroxamate iron(III) complexes chloride and, to lesser extents, bromide and nitrate, catalyze ligand dissociation through transient coordination of the added anion to the iron (344). A catechol derivative of desferrioxamine has been found to remove iron from transferrin about 100 times faster than desferrioxamine itself it forms a significantly more stable product with Fe3+ (345). 

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