Column generation with free replicability in DEA

The evaluation of efficiency scores in data envelopment analysis is based on the construction of artificial decision making units subject to some assumptions, usually requiring convexity of the production possibility set. This demands divisibility in input and output, which is not always possible. The so-called free replicability model, proposed by Henry Tulkens, permits input and output to enter in only discrete amounts. The model is of a mixed integer programming type, for which the number of variables, here corresponding to the decision making units, may be critical in order to reach an optimal solution.     

Emotions and the optimality of uneven tournaments

Standard results from tournament theory show that an employer should avoid organizing uneven tournaments in which workers are characterized by different cost functions. In this paper, we introduce a concept of emotions that workers have when comparing their own performance with the performances of their co-workers. We can show that under emotional workers the employer may prefer uneven tournaments to even ones. In that case, the employer benefits from both positive and negative emotions. Moreover, the behavior of emotional workers fits well with experimental findings on uneven tournaments where players choose excessive effort levels.     

Estimating Consumer Exposure to PFOS and PFOA

Perfluorinated compounds have been used for more than 50 years as process aids, surfactants, and for surface protection. This study is a comprehensive assessment of consumer exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) from a variety of environmental and product-related sources. To identify relevant pathways leading to consumer exposure to PFOS and PFOA a scenario-based approach has been applied. Scenarios represent realistic situations where age- and gender-specific exposure occurs in the everyday life of consumers. We find that North American and European consumers are likely to experience ubiquitous and long-term uptake doses of PFOS and PFOA in the range of 3 to 220 ng per kg body weight per day (ng/kg_bw/day) and 1 to 130 ng/kg_bw/day, respectively. The greatest portion of the chronic exposure to PFOS and PFOA is likely to result from the intake of contaminated foods, including drinking water. Consumer products cause a minor portion of the consumer exposure to PFOS and PFOA. Of these, it is mainly impregnation sprays, treated carpets in homes, and coated food contact materials that may lead to consumer exposure to PFOS and PFOA. Children tend to experience higher total uptake doses (on a body weight basis) than teenagers and adults because of higher relative uptake via food consumption and hand-to-mouth transfer of chemical from treated carpets and ingestion of dust. The uptake estimates based on scenarios are within the range of values derived from blood serum data by applying a one-compartment pharmacokinetic model.     

Parallelizing computation of expected values in recombinant binomial trees

Recombinant binomial trees are binary trees where each non-leaf node has two child nodes, but adjacent parents share a common child node. Such trees arise in option pricing in finance. For example, an option can be valued by evaluating the expected payoffs with respect to random paths in the tree. The cost to exactly compute expected values over random paths grows exponentially in the depth of the tree, rendering a serial computation of one branch at a time impractical. We propose a parallelization method that transforms the calculation of the expected value into an embarrassingly parallel problem by mapping the branches of the binomial tree to the processes in a multiprocessor computing environment. We also discuss a parallel Monte Carlo method and verify the convergence and the variance reduction behavior by simulation study. Performance results from R and Julia implementations are compared on a distributed computing cluster.     

Regression imputation with Q-mode clustering for rounded zero replacement in high-dimensional compositional data

The logratio methodology is not applicable when rounded zeros occur in compositional data. There are many methods to deal with rounded zeros. However, some methods are not suitable for analyzing data sets with high dimensionality. Recently, related methods have been developed, but they cannot balance the calculation time and accuracy. For further improvement, we propose a method based on regression imputation with Q-mode clustering. This method forms the groups of parts and builds partial least squares regression with these groups using centered logratio coordinates. We also prove that using centered logratio coordinates or isometric logratio coordinates in the response of partial least squares regression have the equivalent results for the replacement of rounded zeros. Simulation study and real example are conducted to analyze the performance of the proposed method. The results show that the proposed method can reduce the calculation time in higher dimensions and improve the quality of results.     

Pornographic Picture Processing Interferes with Working Memory Performance

Some individuals report problems during and after Internet sex engagement, such as missing sleep and forgetting appointments, which are associated with negative life consequences. One mechanism potentially leading to these kinds of problems is that sexual arousal during Internet sex might interfere with working memory (WM) capacity, resulting in a neglect of relevant environmental information and therefore disadvantageous decision making. In this study, 28 healthy individuals performed 4 experimental manipulations of a pictorial 4-back WM task with neutral, negative, positive, or pornographic stimuli. Participants also rated 100 pornographic pictures with respect to sexual arousal and indicated masturbation urges previous to and following pornographic picture presentation. Results revealed worse WM performance in the pornographic picture condition of the 4-back task compared with the three remaining picture conditions. Furthermore, hierarchical regression analysis indicated an explanation of variance of the sensitivity in the pornographic picture condition by the subjective rating of the pornographic pictures as well as by a moderation effect of masturbation urges. Results contribute to the view that indicators of sexual arousal due to pornographic picture processing interfere with WM performance. Findings are discussed with respect to Internet sex addiction because WM interference by addiction-related cues is well known from substance dependencies.     

Erosion oder Stabilität der Beruflichkeit?

Regarding the changing patterns of mobility processes in the German labor market, this paper takes up the scientific debate on the declining significance of occupational qualifications. By comparing several labor market entry cohorts, the matching of the learned occupation and the practiced occupation is analyzed in both the horizontal and the vertical dimension of occupational mobility. In doing so, the question of a successful utilization of the skills acquired in the educational process can be addressed. Changes of occupations will be operationalized on the basis of a new professional classification by using the data set “Working and Learning in a Changing World” (ALWA). First, the Kaplan Meier survival curves show that the risks of horizontal occupational mobility have increased across cohorts. This indicates that the formerly close relationship between the education system and the employment system has weakened. Furthermore, according to our multivariate Cox regression analysis, the mobility towards inadequate status positions has increased. Thus, due to the expansion of atypical forms of employment and the increased volatility of the markets, altered mobility patterns of the younger cohorts entering the labor market can be shown. Consequently, the increase of unsuccessful transfers of skills in inter-firm mobility suggests a weakened cohesiveness between professionalism and a growing risk to loose professional qualifications.     

Der Einfluss von Kognition und Affekt auf Unternehmensgründungsentscheidungen: Eine vergleichende Analyse von Angestellten und Unternehmern

The relationship between individuals?? entrepreneurial behavior and objective situational characteristics of an entrepreneurial opportunity??individual-opportunity nexus??lies in the focus of entrepreneurship research. The role of subjective appraisals and affective influences in the pre-entrepreneurial process was neglected in this context so far. On the basis of a questionnaire experiment with two different samples of employees and entrepreneurs, our results confirm central assumptions of cognitive appraisal and emotion theories. The subjective appraisals of objective entrepreneurial opportunities better predict entrepreneurial evaluation and exploitation decisions than the objective characteristics of the entrepreneurial opportunity. Furthermore, the results show in addition to an inverse direct effect of negative affect that the relationship between the entrepreneurial evaluation and exploitation is negatively moderated by negative affect. Our analyses indicate that the two subsamples show differences in their cognitive processes, but that they are still generally comparable. The affective influences on the pre-entrepreneurial process, however, demonstrate no group specific differences. These results extend the individual-opportunity-nexus-paradigm that is based on objective characteristics by examining the meaning of subjective appraisals and affective reactions and therefore the intersection of individuals and entrepreneurial opportunities.     

Der Personalverantwortliche als strategischer Partner

Since Ulrich (Human resource champions: the next agenda for adding value and delivering results, Boston, Harvard Business School Press, 1997) shaped the strategic role of HR managers, his concept of an HR business partner has been controversially discussed by researchers and practitioners. Explanations about when and how HR managers act as strategic business partners have found limited attention in the literature. Based on the theory of reasoned action developed by Ajzen und Fishbein (Understanding attitudes and predicting social behavior, Englewood Cliffs, Prentice-Hall, 1980; J Pers Soc Psychol 27(1):41?C57, 1973), we hypothesize a positive relation between personal attitudes as well as subjective norm and the behaviour of HR managers to act as a strategic business partner. Results of the German Cranet survey in 2009 show that expected positive consequences influence the personal attitude, whereas the acceptance of the human resources as well as the existence of an HR strategy within the organisation is positively related with subjective norm. Hence, both attitude and subjective norm positively influence the behaviour of HR managers to act as a strategic business partner.     

Gastarbeiter in West Germany and Switzerland: an assessment of host society-immigrant relations

West Germany and Switzerland have in general pursued similar immigration policies with respect to alien labor. In spite of a convergence in official policy and a change from temporary migration to settlement in both countries, immigrant groups in West Germany and Switzerland have displayed different attitudes and rates of integration within the host societies. Even when narrowing our discussion to one national group, the Italians, we find substantial differences persist. These cannot be attributed to the percentage of unskilled workers from Italy, intention to stay, the general social climate of the host societies, or even to political institutions such as trade unions. Rather, the higher integration and assimilation of Italians in Switzerland than in Germany appears to be related to structural and demographic factors. Unless policy-makers are aware of the importance of these factors, it is unlikely that they can adequately respond to the complexity and diversity of the problems generated by foreign workers.