Discrete parallel machine makespan ScheLoc problem

Scheduling–Location (ScheLoc) problems integrate the separate fields of scheduling and location problems. In ScheLoc problems the objective is to find locations for the machines and a schedule for each machine subject to some production and location constraints such that some scheduling objective is minimized. In this paper we consider the discrete parallel machine makespan ScheLoc problem where the set of possible machine locations is discrete and a set of n jobs has to be taken to the machines and processed such that the makespan is minimized. Since the separate location and scheduling problem are both \(\mathcal {NP}\)-hard, so is the corresponding ScheLoc problem. Therefore, we propose an integer programming formulation and different versions of clustering heuristics, where jobs are split into clusters and each cluster is assigned to one of the possible machine locations. Since the IP formulation can only be solved for small scale instances we propose several lower bounds to measure the quality of the clustering heuristics. Extensive computational tests show the efficiency of the heuristics.     

Das Eignungsfeststellungsverfahren für angehende Hauptfachstudierende der Soziologie

This article presents preliminary experience with a selection procedure for the diploma study course in sociology at the LMU Munich, which was first implemented in the winter term 2004/05. Furthermore, it examines the consequences of this procedure. The selection procedure, which is limited in time, was established due to high discontinuation rates and a remarkable congestion of the scientific personnel who are particularly involved in the foundation courses. Judicial fundament of the procedure is an “experimental clause” in the Bavarian University Act. First of all we point out that the number of newly registered undergraduates remarkably declined. Even the total number of applicants is lower than in the years before the initiation of the selection procedure. Secondly, we consider the dwindling during the process of the selection procedure. Contrary to some apprehensions it is obvious that applicants with a good university-entrance diploma do not choose possible alternatives, but still consider the diploma study course in sociology. Concerning the overall evaluation of the selection procedure’s consequences our results show thirdly, that the procedure is highly accepted by all parties concerned and that it therefore has to be regarded as an efficient solution to lower the discontinuation rates as well as to cope with the capacity overload.     

Practising transnational citizenship: dual nationality and simultaneous political involvement among emigrants

Acceptance of dual citizenship allows migrants to naturalise in the country of residence (CoR) without giving up their former citizenship. For migrant sending countries the question emerges whether emigrants who acquire another citizenship are less attached to and politically active in the country of origin than those who do not. This would be the assumption of traditional perspectives on migration and citizenship. However, according to the transnational perspective neither multiple nationalities, nor participation in and identification with the CoR, preclude ongoing ties and participation back home. We test these perspectives with survey data on Swiss citizens residing in France, Germany, Italy and the US. Our results suggest that Swiss dual citizens abroad are not significantly less attached to and active in Switzerland than their mono national counterparts. Our data further supports the transnational perspective by showing not only simultaneity, but a mutually reinforcing relationship when transnational citizenship is practised. Identification with, and political participation in, the CoR positively relates to equivalent feelings and activities in the country of origin. Since dual citizenship sets the legal foundation for simultaneous involvement in two countries, it correctly assumes a central place in the study of transnational citizenship.     

The Effect of Rainfall on Migration from Mexico to the United States

There has been very little work on the impact of rainfall on migration from Mexico or even elsewhere. We use satellite data from NASA to examine the effect of the lagged level of rainfall relative to an area's historical average, on migration from small Mexican communities to the United States. Controlling for the level of education, proportion married, and historic migration levels, we find higher levels of rainfall significantly reduce Mexican migration to the United States and a 20 percentage point higher‐than‐normal level of rainfall leads to a predicted 10.3 percent decrease in migration.     

The effects of propensity score weighting on attrition biases in attitudinal,behavioral, and socio-demographic variables in a short-term web-based panel survey

Propensity score weighting often is used to correct for attrition biases in panel surveys. While methodological literature exists on the logic of propensity score weighting and its practical applications, an in-depth discussion is lacking on the effects of using this weighting to correct for attrition biases in attitudinal, behavioral, and socio-demographic variables. By applying a split panel design, we assessed the effects of weighting on attrition biases in 48 attitudinal, 38 behavioral, and 27 socio-demographic variables. Our findings suggest – while acknowledging the estimate-specific nature of bias – first, that biases vary across these types of variables and second, that the effects of propensity score weighting are not homogeneous across the types. Accordingly, a sole reliance on socio-demographics to evaluate attrition in the present panel survey would have resulted in an underestimation of the biases of attitudinal variables and an overestimation of the ability of weighting to cure the negative effects of attrition in behavioral variables.     

Paths towards Family‐friendly Working Time Arrangements: Comparing Workplaces in Different Countries and Industries

Although studies have examined the distribution and conditions of employer‐provided work–family arrangements, we still lack a systematic investigation of how these vary for different countries and industries. Based on the European Working Conditions Survey 2010, this study examines the conditions under which firms provide family‐friendly working time arrangements and what the differences are across four countries (Austria, Denmark, Italy and the UK) and four industries. The impact of employee representatives, employee involvement, manager support and female managers varies across countries and industries because of the institutional environment (prevailing family model, industrial relations) and workforce composition (gender). The impact of employee representatives depends on their co‐determination rights, and the direction of their effect on the prevailing family model (e.g. negative in conservative countries such as Austria) and the gender composition of the workforce (negative in male‐dominated production, but positive in services). Employee involvement in the work organization is significantly positive in Austria and Denmark (both with co‐operative industrial relations), while manager support has the strongest effect in the UK (liberal regime). At the industry level, female supervisors are positively associated with family‐friendly working time arrangements only in the male‐dominated production industry. These findings suggest that the effects of agency variables and their direction vary depending on the institutional context.     

A Didactic Approach Emphasising the Social Habitat as an Attempt to Meet Growing Social Disintegration: teaching in classes with youth of conspicuous behaviour using aesthetic and cultural means of communication

The life conflicts of pupils with behavioural disorders can be examined through their pictures. Conclusions can be drawn not only with regards to the psychological effects of art therapy, but also regarding a didactic orientated at life-circumstances. The pictures drawn by these pupils can give impulses for further aesthetic processes and become the basis for reflection and changes in behaviour. Environment-orientated didactics open the way to an active, but symbolic confrontation with manifest social conflicts. Teachers have to open their classrooms to the actual subcultural subjects and practices of their pupils. The pursuit of existential problems and the effort to find solutions can prepare the ground for new factual learning. In reference to social-philosophic theories, the culture-critical contents of these pictures should also be questioned. The images produced at the edge of society very often are pictures of a torn world.