Bicriteria cost versus service analysis of a distribution network—a case study

In order to improve the distribution system for the Nordic countries the BASF AG considered 13 alternative scenarios to the existing system. These involved the construction of warehouses at various locations. For every scenario the transportation, storage, and handling cost incurred was to be as low as possible, where restrictions on the delivery time were given. The scenarios were evaluated according to (minimal) total cost and weighted average delivery time. The results led to a restriction to only three cases involving only one new warehouse each. For these, a more accurate model for the cost was developed and evaluated, yielding results similar to a simple linear model. Since there were no clear preferences between cost and delivery time, the final decision was chosen to represent a compromise between the two criteria. Copyright © 1999 John Wiley & Sons, Ltd.     

The reciprocal relation between sleep and memory in infancy: Memory‐dependent adjustment of sleep spindles and spindle‐dependent improvement of memories

Sleep spindle activity in infants supports their formation of generalized memories during sleep, indicating that specific sleep processes affect the consolidation of memories early in life. Characteristics of sleep spindles depend on the infant's developmental state and are known to be associated with trait‐like factors such as intelligence. It is, however, largely unknown which state‐like factors affect sleep spindles in infancy. By varying infants’ wake experience in a within‐subject design, here we provide evidence for a learning‐ and memory‐dependent modulation of infant spindle activity. In a lexical‐semantic learning session before a nap, 14‐ to 16‐month‐old infants were exposed to unknown words as labels for exemplars of unknown object categories. In a memory test on the next day, generalization to novel category exemplars was tested. In a nonlearning control session preceding a nap on another day, the same infants heard known words as labels for exemplars of already known categories. Central–parietal fast sleep spindles increased after the encoding of unknown object–word pairings compared to known pairings, evidencing that an infant's spindle activity varies depending on its prior knowledge for newly encoded information. Correlations suggest that enhanced spindle activity was particularly triggered, when similar unknown pairings were not generalized immediately during encoding. The spindle increase triggered by previously not generalized object–word pairings, moreover, boosted the formation of generalized memories for these pairings. Overall, the results provide first evidence for a fine‐tuned regulation of infant sleep quality according to current consolidation requirements, which improves the infant long‐term memory for new experiences.     

The effects of ongoing task absorption on event-based prospective memory in preschoolers

The current study applied a 2 × 2 experimental design to investigate the effects of ongoing task absorption on event-based prospective memory performance of children aged 3 and 5 years. Children were required to label pictures as ongoing task but to remember to refrain from picture naming and to respond to the target cues in a different way as the prospective memory task. Two differently absorbing ongoing tasks (high absorbing scenario game task vs. low absorbing computer-based task) were administered. Results indicated that prospective memory performance of 5-year-old children was significantly better than that of 3-year-old children. Ongoing task absorption affected the ongoing task performance of preschoolers, but not overall prospective memory performance. Only the 3-year-olds were negatively affected by high ongoing task absorption, which was not the case for the 5-year-olds. The findings are discussed within the light of the multiprocess theory.     

The interplay of intention maintenance and cue monitoring in younger and older adults’ prospective memory

The retention phase of a prospective memory (PM) task poses different challenges, including demands to store or maintain an intended action and to realize the right moment for action execution. The interplay of these processes in younger and older adults has not been explored so far. In this study, the authors examined the impact of maintenance load and task focality on PM in 84 younger and in 83 older adults. Results indicated that PM performance and ongoing task response times were strongly affected by maintenance load and age. However, a focality effect only emerged when maintenance load was low but not when attentional resources were deployed for maintaining a more demanding intention. These findings suggest that maintenance and monitoring requirements compete for similar attentional resources. Furthermore, maintenance load may affect postretrieval processes through its impact on working-memory resources, which can restrain the typical advantage of focal over nonfocal PM tasks.     

Screening for Specific Language Impairment in Preschool Children: Evaluating a Screening Procedure Including the Token Test

Specific language impairment (SLI) comprises impairments in receptive and/or expressive language. Aim of this study was to evaluate a screening for SLI. 61 children with SLI (SLI-children, age-range 4–6 years) and 61 matched typically developing controls were tested for receptive language ability (Token Test—TT) and for intelligence (Wechsler Preschool-and-Primary-Scale-of-Intelligence—WPPSI). Group differences were analyzed using t tests, as well as direct and stepwise discriminant analyses. The predictive value of the WPPSI with respect to TT performance was analyzed using regression analyses. SLI-children performed significantly worse on both TT and WPPSI (\(p \le .0001\)). The TT alone yielded an overall classification rate of 79%, the TT and the WPPSI together yielded an overall classification rate of 80%. TT performance was significantly predicted by verbal intelligence in SLI-children and nonverbal intelligence in controls whilst WPPSI subtest arithmetic was predictive in both groups. Without further research, the Token Test cannot be seen as a valid and sufficient tool for the screening of SLI in preschool children but rather as a tool for the assessment of more general intellectual capacities. SLI-children at this age already show impairments typically associated with SLI which indicates the necessity of early developmental support or training. Token Test performance is possibly an indicator for a more general developmental factor rather than an exclusive indicator for language difficulties.     

Why worry about theory‐dependence? Circularity,minimal empiricality and reliability

It is a widely shared view among philosophers of science that the theory‐dependence (or theory‐ladenness) of observations is worrying, because it can bias empirical tests in favour of the tested theories. These doubts are taken to be dispelled if an observation is influenced by a theory independent of the tested theory and thus circularity is avoided, while (partially) circular tests are taken to require special attention. Contrary to this consensus, it is argued that the epistemic value of theory‐dependent tests has nothing to do with the circularity or non‐circularity of the test, but is instead based on the minimal empiricality and reliability of observations. Since theory‐dependence does not in general prevent observations fulfilling these requirements, it should not be regarded as a phenomenon that is basically detrimental, but as neutral with respect to successful scientific knowledge gathering.