Purpose: Assess for an association of wait times to melanoma treatment with overall survival. Methods: Retrospective review of Ontario patients with melanoma, with descriptive and survival analyses. Results: Median wait times were 43 days (interquartile range (IQR), 24-64) for wide local excision (WLE), 59 days (IQR, 41-81) for sentinel lymph node biopsy (SNB), 63 days (IQR, 43-91) for lymph node dissection (LND), 124 days (IQR, 96-150) for medical therapy, and 130 days (IQR, 89.5-157.5) for radiation therapy. In multivariate analysis, wait times to treatment were not associated with overall survival for WLE (hazard ratio (HR), 0.97; 95% confidence interval (CI), 0.87-1.08; p=0.62), SNB (HR, 0.89; 95% CI, 0.74-1.07; p=0.21), LND (HR, 0.99; 95% CI, 0.89-1.11; p=0.92), medical therapy (HR, 0.94; 95% CI, 0.80-1.10; p=0.41) or radiation therapy (HR, 0.80; 95% CI, 0.61-1.03; p=0.08). Conclusion: Overall survival for patients with melanoma was not associated with wait times to surgical, medical or radiation therapy.

No-wait scheduling problem refers to the set of problems in which a number of jobs are available for processing on a number of machines with the added constraint that there should be no waiting time between consecutive operations of the jobs. It is well-known that most of the no-wait scheduling problems are strongly NP-hard. Moreover, no-wait scheduling problems have numerous real-life applications. This thesis studies a wide range of no-wait scheduling problems, along with side constraints that make such problems more applicable. First, 2-machine no-wait flow shop problem is studied. Afterwards, setup times and single server constraints are added to this problem in order to make it more applicable. Then, job shop version of this problem is further researched. Analytical results for both of these problems are presented; moreover, efficient algorithms are developed and applied to large instances of these problems. Afterward, general no-wait flow shop problem (NWFS) is the focus of the thesis. First, the NWFS is studied; mathematical models as well as metaheuristics are developed for NWFS. Then, setup times are added to NWFS in order to make the problem more applicable. Finally, the case of sequence dependent setup times is further researched. Efficient algorithms are developed for both problems. Finally, no-wait job shop (NWJS) problem is studied. Literature has proposed different methods to solve NWJS; the most successful approaches decompose the problem into a timetabling sub-problem and a sequencing sub-problem. Different sequencing and timetabling algorithms are developed to solve NWJS. This thesis provides insight to several no-wait scheduling problems. A number of theorems are discussed and proved in order to find the optimum solution of no-wait problems with special characteristics. For the problems without such characteristics, mathematical models are developed. Metaheuristics are utilized to deal with large-instances of NP-hard problems. Computational results show that the developed methods in this thesis are very effective and efficient compared to the competitive methods available in the literature.

No-wait scheduling problem refers to the set of problems in which a number of jobs are available for processing on a number of machines with the added constraint that there should be no waiting time between consecutive operations of the jobs. It is well-known that most of the no-wait scheduling problems are strongly NP-hard. Moreover, no-wait scheduling problems have numerous real-life applications. This thesis studies a wide range of no-wait scheduling problems, along with side constraints that make such problems more applicable. First, 2-machine no-wait flow shop problem is studied. Afterwards, setup times and single server constraints are added to this problem in order to make it more applicable. Then, job shop version of this problem is further researched. Analytical results for both of these problems are presented; moreover, efficient algorithms are developed and applied to large instances of these problems. Afterward, general no-wait flow shop problem (NWFS) is the focus of the thesis. First, the NWFS is studied; mathematical models as well as metaheuristics are developed for NWFS. Then, setup times are added to NWFS in order to make the problem more applicable. Finally, the case of sequence dependent setup times is further researched. Efficient algorithms are developed for both problems. Finally, no-wait job shop (NWJS) problem is studied. Literature has proposed different methods to solve NWJS; the most successful approaches decompose the problem into a timetabling sub-problem and a sequencing sub-problem. Different sequencing and timetabling algorithms are developed to solve NWJS. This thesis provides insight to several no-wait scheduling problems. A number of theorems are discussed and proved in order to find the optimum solution of no-wait problems with special characteristics. For the problems without such characteristics, mathematical models are developed. Metaheuristics are utilized to deal with large-instances of NP-hard problems. Computational results show that the developed methods in this thesis are very effective and efficient compared to the competitive methods available in the literature.

Reducing emergency department (ED) wait times are a major priority for the Ontario Government. Overcrowded EDs, cumulative effects of the delays in hospital processes and lack of resources are manifested in the phenomenon of long wait times. This thesis aims to estimate in real-time, a minimum wait time confidence interval for urgent abdominal pain patients on weekdays based on ED operations, waiting room status and ED census indicators through multivariate backwards stepwise regression modeling. The ED wait times model accurately predicted a 95% wait time confidence interval for patients. Common underlying factors attributed to long wait times include the total number of emergent and urgent patients in the waiting room, the total number of patient waiting for a consultation and the number of patients not seen within the Ontario Government’s target times. This information is useful in managing patient expectations and appropriately allocating resources to improve wait times.

Reducing emergency department (ED) wait times are a major priority for the Ontario Government. Overcrowded EDs, cumulative effects of the delays in hospital processes and lack of resources are manifested in the phenomenon of long wait times. This thesis aims to estimate in real-time, a minimum wait time confidence interval for urgent abdominal pain patients on weekdays based on ED operations, waiting room status and ED census indicators through multivariate backwards stepwise regression modeling. The ED wait times model accurately predicted a 95% wait time confidence interval for patients. Common underlying factors attributed to long wait times include the total number of emergent and urgent patients in the waiting room, the total number of patient waiting for a consultation and the number of patients not seen within the Ontario Government’s target times. This information is useful in managing patient expectations and appropriately allocating resources to improve wait times.

国立情報学研究所で電子化したコンテンツを使用している。

Syftet med den här studien var att öka kunskapen om hur lärare använder tystnad då de ställer frågor tillelever i matematikundervisningen. Inom forskningsfältet för pedagogik är samtalets fördelar förutvecklandet av matematiska kunskaper vida spritt, mindre berörs tystnadens fördelar inom samma område.Vi utförde en flermetods-studie vars främsta metod var ljudupptagningar i syfte att mäta längden avtystnader i anslutning till frågor under lektioner. Det insamlade materialet analyserades i flera steg, främstgenom att använda Rowes (1974) teori om wait-time. Resultaten visade att lärarna i studien använde tystnadi låg utsträckning, sällan mer än 3 sekunder i anslutning till frågor. Den genomsnittliga tystnaden var mellan0 och 2,3 sekunder, där 0 betyder att tystnaden var obefintlig. Resultatet blev i slutändan för småskaligt föratt kunna generaliseras men kan ge både blivande och verksamma lärare en tankeställare om hur deanvänder tystnad i matematikundervisningen. Vårt resultat stämde överens med resultat från tidigareforskning inom samma område, att lärare använder tystnad i liten utsträckning. Varför tystnad används i såliten utsträckning är ett område som behöver vidare forskning.

Este trabalho apresenta o problema de programação de operações em máquinas no ambiente no-wait flowshop com o critério de minimização da duração total da programação. Aplicações para o problema no-wait flowshop podem ser encontrados em muitas indústrias, por exemplo, em indústrias de processamento de metais, químicos e farmacêuticos. Neste trabalho, são propostos e avaliados novos métodos heurísticos para o problema, e a superioridade do melhor método proposto é comprovada através uma extensa experimentação computacional. / This work deals with the no-wait flowshop scheduling problem with the objective of minimizing total completion time. Applications of no-wait flowshop can be found in many industries, for example, in steel factories, chemical and pharmaceutical. In this work, we propose evaluate new heuristics methods for the problem. Experimental results show that the best proposed heuristic provides better solutions concerning both the solution quality and computational effort.

Este trabalho apresenta o problema de programação de operações em máquinas no ambiente no-wait flowshop com o critério de minimização da duração total da programação. Aplicações para o problema no-wait flowshop podem ser encontrados em muitas indústrias, por exemplo, em indústrias de processamento de metais, químicos e farmacêuticos. Neste trabalho, são propostos e avaliados novos métodos heurísticos para o problema, e a superioridade do melhor método proposto é comprovada através uma extensa experimentação computacional. / This work deals with the no-wait flowshop scheduling problem with the objective of minimizing total completion time. Applications of no-wait flowshop can be found in many industries, for example, in steel factories, chemical and pharmaceutical. In this work, we propose evaluate new heuristics methods for the problem. Experimental results show that the best proposed heuristic provides better solutions concerning both the solution quality and computational effort.

This dissertation explores the necessary and sufficient conditions to solve a variant of the dining philosophers problem. This dining variant is defined by three properties: wait-freedom, eventual weak exclusion, and eventual bounded fairness. Wait-freedom guarantees that every correct hungry process eventually enters its critical section, regardless of process crashes. Eventual weak exclusion guarantees that every execution has an infinite suffix during which no two live neighbors execute overlapping critical sections. Eventual bounded fairness guarantees that there exists a fairness bound k such that every execution has an infinite suffix during which no correct hungry process is overtaken more than k times by any neighbor. This dining variant (WF-EBF dining for short) is important for synchronization tasks where eventual safety (i.e., eventual weak exclusion) is sufficient for correctness (e.g., duty-cycle scheduling, self-stabilizing daemons, and contention managers). Unfortunately, it is known that wait-free dining is unsolvable in asynchronous message-passing systems subject to crash faults. To circumvent this impossibility result, it is necessary to assume the existence of bounds on timing properties, such as relative process speeds and message delivery time. As such, it is of interest to characterize the necessary and sufficient timing assumptions to solve WF-EBF dining. We focus on implicit timing assumptions, which can be encapsulated by failure detectors. Failure detectors can be viewed as distributed oracles that can be queried for potentially unreliable information about crash faults. The weakest detector D for WF-EBF dining means that D is both necessary and sufficient. Necessity means that every failure detector that solves WF-EBF dining is at least as strong as D. Sufficiency means that there exists at least one algorithm that solves WF-EBF dining using D. As such, our research goal is to characterize the weakest failure detector to solve WF-EBF dining. We prove that the eventually perfect failure detector 3P is the weakest failure detector for solving WF-EBF dining. 3P eventually suspects crashed processes permanently, but may make mistakes by wrongfully suspecting correct processes finitely many times during any execution. As such, 3P eventually stops suspecting correct processes.