This assessment found ergonomic risks mainly in the trunk, arm/forearm, and legs; the neck and hand/wrist were also compromised. Opportunities for ergonomic analyses and interventions in the design and execution of computer repair tasks are discussed.

We give a necessary and sufficient condition on a function f : R → R under which the composition operator (Nemytskij operator)and satisfies a local Lipschitz condition. While the proof of sufficiency consists in a straightforward calculation, the proof of necessity builds on nontrivial arguments like Helly's selection principle or the Arzelà-Ascoli compactness criterion.

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Summary. Let (X, · ) and (Y, · ) be two normed spaces and K be a convex cone in X. Let CC(Y ) be the family of all non-empty convex compact subsets of Y . We consider the Nemytskiȋ operators, i.e. the composition operators defined by (N u )(t) = H(t, u(t)),where H is a given set-valued function. It is shown that if the operator N maps the space b]; CC(Y )) (both are spaces of functions of bounded ϕ-variation in the sense of Riesz), and if it is globally Lipschitz, then it has to be of the form H(t, u(t)) = A(t)u(t)+B(t), where A(t)is a linear continuous set-valued function and B is a set-valued function of bounded ϕ 2 -variation in the sense of Riesz. This generalizes results of G. Zawadzka [12], A. Smajdor and W. Smajdor [11], N. Merentes and K. Nikodem [5], and N. Merentes and S. Rivas [7].