Exact estimability of the transfer functions of linear systems

In this paper we show the exact estimability of the transfer functions of linear stochastic systems under two sets of conditions.The main point is to demonstrate the measurability of the “identifying” function.The estimability od the transfer functions is not only of interest for its own but also for the estimability of the system parameters.     

An Empirical Approach to Sufficient Similarity: Combining Exposure Data and Mixtures Toxicology Data

When assessing risks posed by environmental chemical mixtures, whole mixture approaches are preferred to component approaches. When toxicological data on whole mixtures as they occur in the environment are not available, Environmental Protection Agency guidance states that toxicity data from a mixture considered “sufficiently similar” to the environmental mixture can serve as a surrogate. We propose a novel method to examine whether mixtures are sufficiently similar, when exposure data and mixture toxicity study data from at least one representative mixture are available. We define sufficient similarity using equivalence testing methodology comparing the distance between benchmark dose estimates for mixtures in both data‐rich and data‐poor cases. We construct a “similar mixtures risk indicator”(SMRI) (analogous to the hazard index) on sufficiently similar mixtures linking exposure data with mixtures toxicology data. The methods are illustrated using pyrethroid mixtures occurrence data collected in child care centers (CCC) and dose‐response data examining acute neurobehavioral effects of pyrethroid mixtures in rats. Our method shows that the mixtures from 90% of the CCCs were sufficiently similar to the dose‐response study mixture. Using exposure estimates for a hypothetical child, the 95th percentile of the (weighted) SMRI for these sufficiently similar mixtures was 0.20 (i.e., where SMRI <1, less concern; >1, more concern).     

Einkommenseffekte beruflicher Weiterbildung

The claim for lifelong learning or vocational further training is most often set out without having clarified satisfactorily the individual gains which result from training activities. Based on human capital theory, which we extend by arguments from signaling- and game theory, the paper investigates for western and eastern Germany individual returns of training on income with longitudinal data (1996–1998) from the recently available “Mikrozensus-Panel”. A problem in identifying causal training effects is a selection bias caused by unobserved heterogeneity which – using conventional methods – leads to overestimation of the effects. Fixed- and Random-Effects-Models – which we discuss and confront empirically regarding the training issue – present a method for controlling the selection bias. The results show evidence for positive and significant training effects on income, although the actual amount of income growth is low. Whereas no differences by sex were found, separate analyses by age, skill levels and region indicate that not all of the subgroups benefit positively from further training activities. Therefore, the findings relativize the importance of social inequalities in the access to further training for the process of status attainment in general.     

Bisphenol A: How the Most Relevant Exposure Sources Contribute to Total Consumer Exposure

Bisphenol A (BPA) is an endocrine disrupting chemical that is found in human urine throughout industrial societies around the globe. Consumer exposure pathways to BPA include packaged food, household dust, air, and dental fillings. To date, information on the relative contribution of the different pathways to total consumer exposure is lacking, but is key for managing substance‐associated risks. We investigated the relative contributions of the pathways known to be most relevant for nine different consumer groups. Our results suggest that the most important pathways for infants and children are the use of polycarbonate (PC) baby bottles and for adults and teenagers the consumption of canned food. Dental surgery can also considerably contribute over a short time directly after the surgery. For infants fed with PC baby bottles with mean dose rates of 0.8 μg/kg_bw/d the highest exposure dose rate was calculated. This dose rate is far below the tolerable daily intake of 50 μg/kg_bw/d. However, it is of the same order of magnitude as recently reported concentrations that caused low‐dose health effects in rodents. We find a pattern of falling exposure levels with rising age that is supported by urinary concentrations of BPA available for selected consumer groups. Similarly, the exposure levels we predict are confirmed by the levels reported in these studies.     

Hierarchische Planung für industrielle Logistikdienstleister

In this paper a planning and control system for logistics service providers (called LPS system) is developed under consideration of their specific flexibility potentials. Due to the complexity of such planning decisions (different planning levels and data quality of these levels as well as time horizons etc.), a multi-stage, hierarchical planning system is proposed which minimizes the relevant costs under consideration of the flexibilities. The advantage of a hierarchical planning concept consists in a limited planning complexity because otherwise data collection and solution development would lead to unsolvable problems in practice. The results of using LPS systems for a real-life case show a significant pay-off for logistics service providers due to the remarkable cost savings by applying a hierarchical planning concept.     

Leitung mit Supervisionskompetenz

The author describes a position of a supervisor in a clinical institution, which he would have rejected some years ago??to adopt a management role as supervisor and to act mainly in the role of a supervisor. But the recent experiences have shown, that this may be possible and successful. This is illustrated by a case study.     

Push-Kanban – a kanban-based production control concept for job shops

Job-shop production in an individual and small-batch manufacturing environment demands producing simultaneously different products in many customised versions and in small numbers. The associated variability of the time-phased work content leads to a high degree of complexity and turbulence in the manufacturing process of such a production type. Therefore, production control becomes significantly more complicated, and many theories on how to cope fail in the real world. Despite the many technological and conceptual advances in the field of job-shop control over the past few decades, there is still a remarkable lack of practical control approaches for job-shop production. For this reason the Push-Kanban production control concept will be introduced in this article. It combines robust push scheduling along with a kanban-driven, decentralised inventory control mechanism to create a holistic control approach, integrating all production control tasks. Thus, it offers a feasible option for controlling job-shop production in industrial practice. This article examines the effectiveness of the concept by means of a simulation study based on real data.     

Changes in the structure of health complaints as related to shiftwork exposure

Abstract

Factor analyses of health complaints in groups with different length of shiftwork exposure show that the structure of these complaints changes with increasing shift experience, indicating the emergence of a shift-specific pattern of health complaints. After about 15 years of shiftwork, complaints related to disturbances of circadian-controlled functions can be found in the first factor whereas other complaints have their dominant loadings on a separate factor, representing general, non-shift-specific impairments. The results indicate that in this way shift-specific components of health impairment can be separated from other non-shift related components.     

A game theoretical analysis of an extended manager-auditor-conflict

Horst Albach has dealt in his research very often with problems of the quality of balance auditing (Albach 1992, 2003). Sometimes his considerations show close relations to the current crisis of the financial market and its consequences. Some of his contributions were already made in times, when it was not yet expected that the dependency of auditors from clients could once become a serious deficit of auditing. Those aspects also become relevant now in connection with the crisis of the financial market.The misgivings that arise continuously in this context with regard to the correctness of submitted balance sheets have sparked off intense discussions in two directions in the Federal Republic of Germany. Whereas the USA has already realised a prohibition of this nature to a great extent through statutory provisions, a broad spectrum of additional consultancy services is still permissible in the Federal Republic of Germany in spite of similar initiatives on the part of legislators.The present paper analyses methodically in the framework of an extended manager–auditor game how the Nash equilibrium is altered in a non-cooperative two-person game through the behaviour of the players, if the supervisory board, as an exogenous party, detects with a specific probability the incorrect certification of a substantively incorrectly prepared balance sheet. At the same time, payoffs from consultancy services for both players are included in the analysis here. However, with a greater probability of detection of an incorrectly certified incorrect balance sheet, and through the reductions of consultancy payoffs, the supervisory board can work towards the product of audit and publication quality being increased.