Optimization problems with color-induced budget constraints

In 1984, Gabow and Tarjan provided a very elegant and fast algorithm for the following problem: given a matroid defined on a red and blue colored ground set, determine a basis of minimum cost among those with k red elements, or decide that no such basis exists. In this paper, we investigate extensions of this problem from ordinary matroids to the more general notion of poset matroids which take precedence constraints on the ground set into account. We show that the problem on general poset matroids becomes -hard, already if the underlying partially ordered set (poset) consists of binary trees of height two. On the positive side, we present two algorithms: a pseudopolynomial one for integer polymatroids, i.e., the case where the poset consists of disjoint chains, and a polynomial algorithm for the problem to determine a minimum cost ideal of size l with k red elements, i.e., the uniform rank-l poset matroid, on series-parallel posets.     

State of scientific knowledge about the need of recovery time at specific workplaces and recommendations for further research

Research activities to determine the need of recovery time at work were mainly performed in the 1970s and 1980s. Previous studies were largely based on expert opinions or were generated within small and non-representative groups. Often, laboratory experiments were carried out with a low number of subjects. Especially during the last decade, only little additional scientific knowledge was generated on this topic. The very resource intensive development of more detailed results based on the existing level of scientific knowledge is assumed as one reason for this. In general, it seems to be reasonable to continue further research on the knowledge generated in previous studies, but implement larger samples and more representative groups. Besides, according to monotonous manual work, more research is especially needed regarding relative operating forces and operation frequencies taken grip conditions and hand/body position into account.     

Evaluation of objectivity, reliability and criterion validity of the key indicator method for manual handling operations (KIM-MHO), draft 2007

Upper extremity musculoskeletal symptoms and disorders are common in the working population. The economic and social impact of such disorders is considerable. Long-time, dynamic repetitive exposure of the hand-arm system during manual handling operations (MHO) alone or in combination with static and postural effort are recognised as causes of musculoskeletal symptoms and disorders. The assessment of these manual work tasks is crucial to estimate health risks of exposed employees. For these work tasks, a new method for the assessment of the working conditions was developed and a validation study was performed. The results suggest satisfying criterion validity and moderate objectivity of the KIM-MHO draft 2007. The method was modified and evaluated again. It is planned to release a new version of KIM-MHO in spring 2012.     

Designing dynamic distributed cooperative Human-Machine Systems

The paper presents a new approach to the development of cooperative human-machine systems in the Transportation domain which is currently researched in the European project D3CoS. A necessary precondition for the acceptance of cooperative human-machine systems with shared control is the confidence and trust of the user into the system. D3CoS tackles this important issue by addressing the cooperative system as the object and the target of the system development process. This new perspective, along with corresponding innovative methods, techniques and tools, shall allow the identification of optimal task and authority sharing approaches supported by intuitive human-machine interaction and user interfaces at an early stage of system development. This will support powerful teamwork between humans and machines or between machines and machines that is transparent, intuitive and easy to understand. The paper describes the research dimensions for the development of the methods, techniques and tools as well as first results.     

Promoting work ability and well-being in hospital nursing: the interplay of age, job control, and successful ageing strategies

Previous research shows that work ability of nurses decreases with age. In our study we therefore addressed the following questions: Do successful ageing strategies at work in terms of selection, optimization, and compensation (SOC) support the work ability of nurses? Does SOC mediate the relationship between job control (i.e., decision opportunities at work) and work ability? Does the mediation differ between age-groups? 438 nurses (Age Range 21-63 years) completed a questionnaire in the course of an employee survey. Results show that SOC is positively related with work ability. The positive effect of job control on work ability is significantly mediated by SOC. There are stronger mediating effects for elder nurses than for younger nurses. Results indicate that the interplay of job control and SOC at work helps to maintain the work ability of nurses in nursing care.     

Consolidated findings from 6 years research on the age-differentiated design of human-computer interaction

The fast aging of many western and eastern societies and their increasing reliance on information technology create a compelling need to reconsider older users' interactions with computers. This paper summarizes the results of 6 years of research on the age-differentiated design of human-computer interaction. The well-known model of human information processing served as the theoretical framework. The model components 'sensory processing', 'perception', 'working memory', 'decision and response selection' and 'response execution' were analyzed exemplarily in task settings on project management. In seven empirical studies with a total number of 405 participants between 20 and 77 years the human-computer interaction was analyzed regarding effectiveness, efficiency and user satisfaction. For most but not all studies the results reveal that age-induced differences in human-computer interaction can best be compensated by an ergonomic 'design for all'. In some cases however an age-specific approach is favorable.     

Manual flying skills under the influence of performance shaping factors

This paper describes an experimental study investigating pilots' manual flying skills. In today's line oriented flight training, basic flying skills are neglected frequently. So, the study examines the manual flying skills of commercial airline pilots under the influence of several performance shaping factors like training, practice or fatigue in a landing scenario. The landing phase shows a disproportionate high percentage of aircraft accidents and it is typically flown by hand. The study is to be undertaken with randomly selected pilots in a full motion flight simulator to ensure a high validity of the results.     

The relevance of temporal iconicity with instruction manuals for elderly users

Gerontolinguistic obtains a growing importance with the increase of elderly users due to Demographic Change. Since acceptance and ease of use of supportive systems for elderly, such as "E-Nursing-Assistants", are highly dependent on the age suitable design of readable instructions, an age-appropriate linguistic concept is of high value for usability. There has been only little research on the relevance of foreign words, signal words, textual arrangement, optical accentuation of key terms and temporal iconicity concerning older users. Thus, an efficient design of age suitable manual instructions within a medical context still remains to be done. The objective of this research was to evaluate the relevance of the previously mentioned factors in the context of written instructions. For this, an empirical survey was designed which was given to 45 study participants. The subjects of the experiment were given 4x3 instructions after a pretest questionnaire. The aim was to execute these instructions as correctly and quickly as possible. Furthermore the instructions were rated regarding comprehensibility with a retrospective questionnaire.