Genetic algorithm optimisation of water consumption and wastewater network topology

Genetic algorithm (GA) optimisation applied to water systems with multiple contaminants and several contaminated sources is presented. This approach generates the overall optimal water network topology with respect to the minimum supply water usage, complying, in the same time, with all restrictions. An optimal water network could be viewed as an oriented graph, starting from unit operations which must not have contaminants at entrance (inlet contaminants-free unit operations), every next unit operation i receiving streams from the previous operations j only (j = 1, 2,…,i−1), and sending streams to the next operations j (j = i + 1, i + 2,…,N). The mathematical model describing the unit i is based upon total and contaminant species’ mass balances, together with the input and output constraints. Solving this optimisation problem is not trivial, since the unknowns' number, determines the number of equations. The GA optimisation uses each network's internal flow as a gene, assembling the topology into a chromosome. The restrictions, in terms of minimum and maximum allowable flows for each gene, are dealt with naturally, during the population generation, simply rejecting those genes outside their feasible domain. The individuals are interbred according to their frequency of selection, using the one-point crossover method, and then mutations are applied to randomly selected individuals. The objective function is the total supply water consumption, which should be minimised.     

Long-term outcome after intrauterine laser treatment for twin–twin transfusion syndrome

Twin–twin transfusion syndrome (TTTS) is a severe complication occurring in about 10% of monochorionic twin pregnancies. The chronic unbalanced transfusion of blood across placental vascular communications from the donor to the recipient twin may lead to impairment of various organ systems in the affected twins. In Hamburg, Germany, since 1995 patients with TTTS were treated with fetoscopic laser coagulation as the first causal therapeutic strategy. All survivors after laser surgery were followed up in the University Children's Hospital in Bonn, Germany. In this article, we summarize long-term follow-up studies from our German study population and compare our results with data from the literature. Copyright © 2011 John Wiley & Sons, Ltd.     

Thriving at work—A diary study

The present diary study examines how employees thrive at work in response to resources (i.e., positive meaning, relational resources, and knowledge). Thriving is conceptualized as the joint experience of vitality and learning. A total of 121 employees working in the social services sector responded to three daily surveys (in the morning, at lunchtime, and at the end of the work day) for a period of five work days. Intra‐individual analyses (hierarchical linear modeling) revealed that on days when employees experience positive meaning at work in the morning, they feel more vital at the end of the work day and have a higher sense of learning. Work behaviors such as task focus and exploration mediated the relation between positive meaning and both components of thriving. Copyright © 2011 John Wiley & Sons, Ltd.     

A comparison of three methods for estimating call densities of migrating bowhead whales using passive acoustic monitoring

Environmental and Ecological Statistics - Various methods for estimating animal density from visual data, including distance sampling (DS) and spatially explicit capture-recapture (SECR), have...