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.     

Towards a 'Movement Society'? On the possibilities of institutionalizing social movements

Social movements come into existence only on the basis of certain preconditions. The concurrence of distinct factors on the levels of individual experience, collective framing and societal structure favour the emergence and stabilization of social movements. Drawing on a model that links these three levels with aspects of problematization, mobilization and stabilization, we argue that there is a growing probability for social movements to come into existence. This probability stems mainly from a set of macro-structural trends and their problematic effects that can be interpreted in terms of differentiation theory. Instead of encompassing and stable class movements as represented, for example, by the labour movement, we expect a multitude of more situationally bound movements that vary considerably in their themes, social bases and forms. It is precisely this heterogeneity of movements that is an enduring feature of contemporary Western societies.     

Scheduling with interjob communication on parallel processors

Consider a scheduling problem in which a set of tasks needs to be scheduled on m parallel processors. Each task \(T_i\) consists of a set of jobs with interjob communication demands, represented by a weighted, undirected graph \(G_i\). The processors are assumed to be interconnected by a shared communication channel, which can be used by jobs to communicate among each other while being processed in parallel. In each time step, the scheduler assigns jobs to the processors and allows any processed job to use a certain capacity of the channel in order to satisfy (parts of) its communication demands to adjacent jobs processed in the same step. The goal is to find a schedule with minimum length in which the communication demands of all jobs are satisfied. We show that this problem is NP-hard in the strong sense even if the number of processors is constant and the underlying graph is a single path or a forest with arbitrary constant maximum degree. Consequently, we design and analyze approximation algorithms with asymptotic approximation ratio \(\min \{1.8, 1.5 \frac{m}{m-1}\}+1\) if the underlying graph G, the union of the \(G_i\), is a forest. For general graphs it is \(\min \left\{ 1.8, \frac{1.5m}{m-1}\right\} \cdot \left( \text {arb}(G) + \frac{5}{3}\right) \), where \(\text {arb}(G)\) denotes the arboricity of G.     

‘Valid’ empirical measurement of quality of life?

Results of empirical quality of life studies, undertaken hitherto, are subjectively influenced to a considerable extent by the researchers who try to measure the ‘quality of life’. In substantiation of this allegation it is shown on the basis of empirical data that the results are highly influenced, among others, (1) by the selection of indicators, (2) by the aggregation of indicators to one element, (3) by the weighting or non-weighting of the indicators, (4) by the indicator weigths given by different groups, (5) by employing different measurement techniques. Remarkable progress in empirical measurement could be made by the employment of objective indicators which are weighted by different groups (e.g., citizens, experts, decision makers, etc.). This approach can be called a ‘weighted objective indicator’ approach. In the second half of the article the proposal is made to measure infrastructure disparities both in physical and monetary terms. This permits a comprehensive assessment of the infrastructure's deficits and surplus on the level of indicators, subconcerns, and concerns.     

Towards the price of leasing online

We consider online optimization problems in which certain goods have to be acquired in order to provide a service or infrastructure. Classically, decisions for such problems are considered as final: one buys the goods. However, in many real world applications, there is a shift away from the idea of buying goods. Instead, leasing is often a more flexible and lucrative business model. Research has realized this shift and recently initiated the theoretical study of leasing models (Anthony and Gupta in Proceedings of the integer programming and combinatorial optimization: 12th International IPCO Conference, Ithaca, NY, USA, June 25–27, 2007; Meyerson in Proceedings of the 46th Annual IEEE Symposium on Foundations of Computer Science (FOCS 2005), 23–25 Oct 2005, Pittsburgh, PA, USA, 2005; Nagarajan and Williamson in Discret Optim 10(4):361–370, 2013) We extend this line of work and suggest a more systematic study of leasing aspects for a class of online optimization problems. We provide two major technical results. We introduce the leasing variant of online set multicover and give an \(O\left( \log (mK)\log n\right) \)-competitive algorithm (with n, m, and K being the number of elements, sets, and leases, respectively). Our results also imply improvements for the non-leasing variant of online set cover. Moreover, we extend results for the leasing variant of online facility location. Nagarajan and Williamson (Discret Optim 10(4):361–370, 2013) gave an \(O\left( K\log n\right) \)-competitive algorithm for this problem (with n and K being the number of clients and leases, respectively). We remove the dependency on n (and, thereby, on time). In general, this leads to a bound of \(O\left( l_{\text {max}} \log l_{\text {max}} \right) \) (with the maximal lease length \(l_{\text {max}} \)). For many natural problem instances, the bound improves to \(O\left( K^2\right) \).     

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

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.     

Working shifts—different effects for women and men?

Abstract

Results are reported of a survey on the effects of shiftwork on women and men working rotating shifts under comparable job conditions. Discriminant analyses revealed that gender-related effects of shiftwork could not be found. However, off-the-job work stress, e.g. a gender-related unequal division of domestic duties, clearly differentiated between women and men and the presence or absence of children in the house. The ‘double burden’ for women, in particular for those with children, did not result in more severe psychosocial or subjective health impairments.