Constructing robust crew schedules with bicriteria optimization

Optimization‐based computer systems are used by many airlines to solve crew planning problems by constructing minimal cost tours of duty. However, today airlines do not only require cost effective solutions, but are also very interested in robust solutions. A more robust solution is understood to be one where disruptions in the schedule (due to delays) are less likely to be propagated into the future, causing delays of subsequent flights. Current scheduling systems based solely on cost do not automatically provide robust solutions. These considerations lead to a multiobjective framework, as the maximization of robustness will be in conflict with the minimization of cost. For example crew changing aircraft within a duty period is discouraged if inadequate ground time is provided. We develop a bicriteria optimization framework to generate Pareto optimal schedules for the domestic airline. A Pareto optimal schedule is one which does not allow an improvement in cost and robustness at the same time. We developed a method to solve the bicriteria problem, implemented it and tested it with actual airline data. Our results show that considerable gain in robustness can be achieved with a small increase in cost. The additional cost is mainly due to an increase in overnights, which allows for a reduction of the number of aircraft changes. Copyright © 2003 John Wiley & Sons, Ltd.     

The multiple-stimulus-without-replacement preference assessment tool and its predictive validity

This study demonstrates the use of two web-based programs, one to identify video preferences and the other to assess their reinforcing effects. We used the Multiple-Stimulus-Without-Replacement Preference Assessment Tool (MSWO PAT) to identify the video preference hierarchies of seven participants, ages 4–11 years old. We then used a customized reinforcer assessment program that arranged a concurrent-chains preparation with programmed conjugate schedules of reinforcement. Button presses emitted by participants modulated the quality (volume and opacity) of selected videos on a moment-to-moment basis, allowing us to identify the reinforcing effects of the videos in little time. The results showed that the preference assessment had predictive value for five of seven participants. We discuss the MSWO PAT, parameters that may affect the identification of preferences and the use of conjugate schedules to identify reinforcers.     

Homework

In commemoration of Dr. Aaron T. Beck’s enormous contributions to our field, I comment on the state of our knowledge regarding the role of homework in cognitive behavioral therapy. The available evidence suggests homework is a contributor to positive therapeutic outcomes in cognitive behavioral therapy. Although therapists play an important role in facilitating clients’ engagement with homework as they develop greater facility with CBT skills, little is known about the contributions of specific approaches to promoting homework engagement. I highlight some of these strategies and discuss the need for researchers to empirically evaluate them.     

Depression

Beck initially set out to test the Freudian notion that depression is a consequence of “anger turned inward” (rage directed the introjected parent for not gratifying infantile desires) but soon came to conclude that no such unconscious motivation existed and that instead depressed patients actually believe that they were unlovable or inadequate. He developed a treatment that he named cognitive therapy that is as efficacious as and more enduring than antidepressant medications. It stands as the most often tested and most widely practiced treatment for depression.     

Cognitive Reappraisal

A central tenet of Beck’s cognitive therapy (or cognitive behavior therapy) of the emotional disorders is that change in negative thought and beliefs is necessary for clinically significant symptom reduction in anxiety, depression, and other psychological conditions. Cognitive restructuring, a uniquely Beckian innovation, is a treatment strategy that directly targets cognitive reappraisal as the change mechanism responsible for symptom reduction. This commentary considers the origins of cognitive reappraisal in Beck’s cognitive therapy through the lens of cognitive restructuring and what treatment process research tells us about the mechanisms of change in cognitive restructuring.     

Adaptations for Youth

Aaron T. Beck exemplified the clinical scientist, willing to test his hypotheses, and willing to share his experiences and treatment features with others. Assessment and treatment of emotional disorders have been forever improved through the efforts of Aaron T. Beck. Using the psychological treatment of an emotional disorder in youth (i.e., anxiety), this commemorative reflects on how Aaron T. Beck’s clinical strategies have been impactful well beyond his initial focus. As a world-renowned clinical scientist, Beck’s work has influenced multiple fields addressing mental health. As a friend and colleague, Beck was a gentleman and a scholar.     

Introduction to the Beck Commemorative Special Feature

My father, Aaron Beck (“Tim” to those closest to him), would have been proud of this special issue of Cognitive and Behavioral Practice, and so honored. Anyone who knew my father, knew he was a scientist at heart. His curiosity, intelligence, and humility made him a great scientist and a productive researcher. This introduction shares a personal perspective and context for his contributions, including his lifelong commitment to enhancing the evidence for cognitive and behavioral practice.     

The effect of a delayed weekend sleep pattern on sleep and morning functioning

Abstract

It is a common practice for young adults to delay their weekend sleep schedule. The present study was designed to assess the effect of this sleep pattern on the sleep of Sunday night and the functioning of Monday morning. The sleep schedules of 30 young adults were manipulated for 2 consecutive weeks. In the Habitual-Sleep (HS) week, subjects followed their habitual sleep schedule throughout the week; in the Delayed-Sleep (DS) week, subjects' sleep schedule on Friday and Saturday nights were delayed by two hours. Compared to the HS week, subjects showed significantly lower subjective sleepiness near bedtime and trends of longer sleep onset latency on Sunday night in the DS week. In addition, there was both lowered cognitive performance and overall mood rating on Monday morning in the DS week. The delayed weekend sleep pattern contributes to Sunday night insomnia and the Monday morning “blues”.     

Effects of Si addition on the microstructure evolution of Al–Cu–Mg alloys in the α + S + T phase field

The precipitation behaviour and age-hardening response of Al–1.5Cu–4.0Mg (wt.%) alloys microalloyed with Si have been investigated by means of hardness measurement, TEM and HRTEM. Compared to the ternary alloy, the quaternary alloys exhibit a higher hardness. It is found that the underaged microstructure in the Al–1.5Cu–4.0?Mg alloy contains some fine precipitates, which are identified as the T phase by FFT spectra. The peak-aged microstructures of the ternary alloy is dominated by the T phase, while the peak-aged microstructures of the Si-containing alloys are dominated by the S phase. The volume fraction of the S phase is found to increase as more Si is added.     

儿童欺负/受欺负与同伴网络的关系：p*模型分析

从四所小学的10个班中挑选出高欺负-受欺负班和低欺负-受欺负班,使用p^*模型分析班内朋友关系的网络结构特点及其与欺负、受欺负的关系。结果发现：（1）低欺负-受欺负班级中的同伴关系网络倾向于形成开放性朋友关系结构,如边、2-星、3-星、4-星结构;高欺负-受欺负班级中的同伴关系网络倾向于形成闭合性朋友关系结构,如三角形、孤立者结构;（2）高、低欺负-受欺负班级中,欺负者均处于同伴关系网络的边缘化位置,且所处的关系结构位置与自身欺负水平的关联不显著;（3）受欺负者所处的关系结构位置与自身受欺负水平的关联也不显著,但是在低欺负-受欺负班中,受欺负者倾向处于同伴关系网络的边缘化位置,而高欺负-受欺负班中,部分受欺负者处于边缘化位置,部分受欺负者处于闭合性关系结构的核心位置。