The Effects of Learning,Forgetting, and Relearning on Decision Rule Performance in Multiproject Scheduling

Product development occurs in multiproject environments where preemption is often allowed so that critical projects can be addressed immediately. Because product development is characterized by time-based competition, there is pressure to make decisions quickly using heuristics methods that yield fast project completion. Preemption heuristics are needed both to choose activities for preemption and then to determine which resources to use to restart preempted activities. Past research involving preemption has ignored any completion time penalty due to the forgetting experienced by project personnel during preemption and the resulting relearning time required to regain lost proficiency. The purpose of this research is to determine the impact of learning, forgetting, and relearning (LFR) on project completion time when preemption is allowed. We present a model for the LFR cycle in multiproject development environments. We test a number of priority rules for activity scheduling, activity preemption, and resource assignment subsequent to preemption, subject to the existence of the LFR cycle, for which a single type of knowledge worker resource is assigned among multiple projects. The results of the simulation experiments clearly demonstrate that LFR effects are significant. The tests of different scheduling, preemption, and resource reassignment rules show that the choice of rule is crucial in mitigating the completion time penalty effects of the LFR cycle, while maintaining high levels of resource utilization. Specifically, the worst performing rules tested for each performance measure are those that attempt to maintain high resource utilization. The best performing rules are based on activity criticality and resource learning.     

The religious and worldview dimension of intercultural education: the Council of Europe’s contribution

ABSTRACT

This article traces the Council of Europe’s work on teaching about religions and non-religious worldviews, regarded as an important contributor to intercultural education. It explains why studies of religions came late in the Council of Europe’s educational work and traces the development of a project which led to a Recommendation from its Committee of Ministers on teaching about religions and non-religious worldviews. It summarises follow-up work by the Council of Europe and the European Wergeland Centre, which led to the publication of Signposts. It outlines new research on themes identified in Signposts and discusses the relationship between intercultural education and studies of religions, in the context of the Council of Europe and responds to criticisms of its work. An account of the development of a new teacher training module, based on Signposts, is given. The module can be adapted for use in Council of Europe member states and in different settings, including university and school-based teacher training. An account is given of the work of the module’s writing group, its structure and chapters, the piloting undertaken and how it could develop. Finally, this article introduces the concept of ‘dialogical liberalism’, aiming to promote dialogue and discussion, rather than imposing equality.     

Cystatin C as a predictor of mortality in elderly patients with chronic kidney disease

Background: The prevalence of chronic kidney disease (CKD) in the elderly is high. Serum cystatin C is an accurate marker of kidney function and it also has prognostic utility in CKD patients. The aim of our study was to determine the prediction of serum cystatin C and other markers of kidney function on long-term survival in elderly CKD patients.

Methods: Fifty eight adult Caucasian patients, older than 65 years, without known malignancy, thyroid disease and/or not on steroid therapy were enrolled in the study. In each patient, ⁵¹CrEDTA clearance, serum creatinine, serum cystatin C, and estimated glomerular filtration rate using different equations were determined on the same day and patients were then followed for 11 years or until their death.

Results: The means are as follows: ⁵¹CrEDTA clearance 53.3?±?17.4?ml/min/1.73?m², serum creatinine 1.62?±?0.5?mg/dl, serum cystatin C 1.79?±?0.5?mg/l, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation 40.1?±?14?ml/min/1.73?m², Berlin Initiative Study 2 (BIS2) equation 38.9?±?10.7?ml/min/1.73?m², full age spectrum (FAS) creatinine equation 43.8?±?13.8?ml/min/1.73?m², FAS cystatin C equation 40.1?±?11.7?ml/min/1.73?m². In the follow up period, 47 (81%) patients died. Cox regression analysis showed different hazard ratios (HRs) for death: for ⁵¹CrEDTA clearance HR 1.022 (95% CI 1.004–1.042; p?=?.015), serum creatinine HR 1.013 (95% CI 1.006–1.019; p?=?.001), serum cystatin C HR 2.028 (95% CI 1.267–3.241; p?=?.003), CKD-EPI creatinine equation HR 1.048 (95% CI 1.019–1.076; p?=?.001), BIS2 equation HR 1.055 (95% CI 1.021–1.088; p?=?.001), FAS creatinine equation HR 1.046 (95% CI 1.017–1.074; p?=?.001), FAS cystatin C equation HR 1.039 (95% CI 1.010–1.071; p?=?.009).

Conclusions: Our results showed the highest HR for serum cystatin C among kidney function markers for prediction of outcome in elderly CKD patients.     

A Time‐Dependent Risk Assessment for Broken Compact Fluorescent Lamps

Environmental Protection Agency (EPA) ambient air quality guidelines are meant to limit long‐term exposures of toxins to safe levels. Unfortunately, there is little guidance for what constitutes a safe level from a one‐time (or very infrequent) short exposure(s). In the case of mercury, a review of the derivation of the EPA ambient air quality standard shows that it implicitly assumes a tissue burden model. The time dependence of the tissue burden is commonly described in terms of a half‐life, a modeling assumption that presumes that the decline in the tissue burden after a single exposure can be approximately described as an exponential decay. In this article, we use a simple exponential tissue burden model to derive a time‐dependent no observable adverse effect level (NOAEL) for mercury concentrations in air. The model predicts that tissue body burden will asymptotically approach the EPA air quality level for long exposure times, and reach workplace standard levels for exposures of a few hours. The model was used along with data on mercury levels from experimental work done by the Maine Department of Environmental Protection to evaluate the risks from a broken compact fluorescent lamp in a residential setting. Mercury levels approached the NOAEL only when the debris was left in an almost sealed room. Normal common‐sense cleaning measures: removal of debris to an outside area, and ventilation of the room for several minutes, reduced exposures to less than 1% of the NOAEL.     

Disagreement in Australian partners’ reports of financial difficulty

We use unique data in which both partners report about household finances to demonstrate that there is often disagreement about whether the household has experienced financial difficulty in the past year. Four alternative explanations for this disagreement are tested using the data. The results indicate that disagreement may be related to the severity of the underlying material hardship rather than to gender differences or individual (as opposed to household) views of financial difficulty. We find limited evidence that for some couples information asymmetries contribute to explaining disagreement about financial difficulty. This implies that standard surveys which collect information about the household’s financial position from a representative individual may fail to completely characterize the nature of material hardship.      

Why do people believe weird things?

From claims that NASA faked the moon landings to creationist rejections of evolution, many people hold views that fl y in the face of evidence. By refusing to be swayed by hard facts, such people are clearly irrational—or are they? Robert Matthews argues that the frustration of scientists over the persistence of "irrational" beliefs highlights their own misconceptions about the process of inference.     

Simple linear regression with multiple level shifts

The authors study the properties of the ordinary least squares trend estimator in a simple linear regression model with multiple known level shift times. The error component in the model is taken to be a general short‐memory stationary time series. The authors establish the consistency and asymptotic normality of the estimator. They also present a climatological application in which the multiple level shifts are prominent features.