Academic literature on the topic 'Time-to-event outcomes'
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Journal articles on the topic "Time-to-event outcomes"
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Stensrud, Mats Julius, Pål Christie Ryalen, and Kjetil Røysland. "Sufficient Cause Interaction for Time-to-event Outcomes." Epidemiology 30, no. 2 (March 2019): 189–96. http://dx.doi.org/10.1097/ede.0000000000000958.
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Clark, David E., and Louise M. Ryan. "Modeling Injury Outcomes Using Time-to-event Methods." Journal of Trauma: Injury, Infection, and Critical Care 42, no. 6 (June 1997): 1129–34. http://dx.doi.org/10.1097/00005373-199706000-00025.
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Gao, Yan, and Yan Cui. "Clinical time-to-event prediction enhanced by incorporating compatible related outcomes." PLOS Digital Health 1, no. 5 (May 26, 2022): e0000038. http://dx.doi.org/10.1371/journal.pdig.0000038.
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Accurate time-to-event (TTE) prediction of clinical outcomes from personal biomedical data is essential for precision medicine. It has become increasingly common that clinical datasets contain information for multiple related patient outcomes from comorbid diseases or multifaceted endpoints of a single disease. Various TTE models have been developed to handle competing risks that are related to mutually exclusive events. However, clinical outcomes are often non-competing and can occur at the same time or sequentially. Here we develop TTE prediction models with the capacity of incorporating compatible related clinical outcomes. We test our method on real and synthetic data and find that the incorporation of related auxiliary clinical outcomes can: 1) significantly improve the TTE prediction performance of conventional Cox model while maintaining its interpretability; 2) further improve the performance of the state-of-the-art deep learning based models. While the auxiliary outcomes are utilized for model training, the model deployment is not limited by the availability of the auxiliary outcome data because the auxiliary outcome information is not required for the prediction of the primary outcome once the model is trained.
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Agarwal, Parul, Erin Moshier, Meng Ru, Nisha Ohri, Ronald Ennis, Kenneth Rosenzweig, and Madhu Mazumdar. "Immortal Time Bias in Observational Studies of Time-to-Event Outcomes." Cancer Control 25, no. 1 (January 1, 2018): 107327481878935. http://dx.doi.org/10.1177/1073274818789355.
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The objectives of this study are to illustrate the effects of immortal time bias (ITB) using an oncology outcomes database and quantify through simulations the magnitude and direction of ITB when different analytical techniques are used. A cohort of 11 626 women who received neoadjuvant chemotherapy and underwent mastectomy with pathologically positive lymph nodes were accrued from the National Cancer Database (2004-2008). Standard Cox regression, time-dependent (TD), and landmark models were used to compare overall survival in patients who did or did not receive postmastectomy radiation therapy (PMRT). Simulation studies showing ways to reduce the effect of ITB indicate that TD exposures should be included as variables in hazard-based analyses. Standard Cox regression models comparing overall survival in patients who did and did not receive PMRT showed a significant treatment effect (hazard ratio [HR]: 0.93, 95% confidence interval [CI]: 0.88-0.99). Time-dependent and landmark methods estimated no treatment effect with HR: 0.97, 95% CI: 0.92 to 1.03 and HR: 0.98, 95% CI, 0.92 to 1.04, respectively. In our simulation studies, the standard Cox regression model significantly overestimated treatment effects when no effect was present. Estimates of TD models were closest to the true treatment effect. Landmark model results were highly dependent on landmark timing. Appropriate statistical approaches that account for ITB are critical to minimize bias when examining relationships between receipt of PMRT and survival.
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Jones, Mark, and Robert Fowler. "Immortal time bias in observational studies of time-to-event outcomes." Journal of Critical Care 36 (December 2016): 195–99. http://dx.doi.org/10.1016/j.jcrc.2016.07.017.
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Williamson, Paula R., Catrin Tudur Smith, Jane L. Hutton, and Anthony G. Marson. "Aggregate data meta-analysis with time-to-event outcomes." Statistics in Medicine 21, no. 22 (2002): 3337–51. http://dx.doi.org/10.1002/sim.1303.
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Berger, Moritz, and Matthias Schmid. "Semiparametric regression for discrete time-to-event data." Statistical Modelling 18, no. 3-4 (January 17, 2018): 322–45. http://dx.doi.org/10.1177/1471082x17748084.
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Abstract: Time-to-event models are a popular tool to analyse data where the outcome variable is the time to the occurrence of a specific event of interest. Here, we focus on the analysis of time-to-event outcomes that are either intrinsically discrete or grouped versions of continuous event times. In the literature, there exists a variety of regression methods for such data. This tutorial provides an introduction to how these models can be applied using open source statistical software. In particular, we consider semiparametric extensions comprising the use of smooth nonlinear functions and tree-based methods. All methods are illustrated by data on the duration of unemployment of US citizens.
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Nielsen, Rasmus Oestergaard, Michael Lejbach Bertelsen, Daniel Ramskov, Merete Møller, Adam Hulme, Daniel Theisen, Caroline F. Finch, Lauren Victoria Fortington, Mohammad Ali Mansournia, and Erik Thorlund Parner. "Time-to-event analysis for sports injury research part 2: time-varying outcomes." British Journal of Sports Medicine 53, no. 1 (November 9, 2018): 70–78. http://dx.doi.org/10.1136/bjsports-2018-100000.
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BackgroundTime-to-event modelling is underutilised in sports injury research. Still, sports injury researchers have been encouraged to consider time-to-event analyses as a powerful alternative to other statistical methods. Therefore, it is important to shed light on statistical approaches suitable for analysing training load related key-questions within the sports injury domain.ContentIn the present article, we illuminate: (i) the possibilities of including time-varying outcomes in time-to-event analyses, (ii) how to deal with a situation where different types of sports injuries are included in the analyses (ie, competing risks), and (iii) how to deal with the situation where multiple subsequent injuries occur in the same athlete.ConclusionTime-to-event analyses can handle time-varying outcomes, competing risk and multiple subsequent injuries. Although powerful, time-to-event has important requirements: researchers are encouraged to carefully consider prior to any data collection that five injuries per exposure state or transition is needed to avoid conducting statistical analyses on time-to-event data leading to biased results. This requirement becomes particularly difficult to accommodate when a stratified analysis is required as the number of variables increases exponentially for each additional strata included. In future sports injury research, we need stratified analyses if the target of our research is to respond to the question: ‘how much change in training load is too much before injury is sustained, among athletes with different characteristics?’ Responding to this question using multiple time-varying exposures (and outcomes) requires millions of injuries. This should not be a barrier for future research, but collaborations across borders to collecting the amount of data needed seems to be an important step forward.
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Gregson, John, Linda Sharples, Gregg W. Stone, Carl-Fredrik Burman, Fredrik Öhrn, and Stuart Pocock. "Nonproportional Hazards for Time-to-Event Outcomes in Clinical Trials." Journal of the American College of Cardiology 74, no. 16 (October 2019): 2102–12. http://dx.doi.org/10.1016/j.jacc.2019.08.1034.
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Sugimoto, Tomoyuki, Toshimitsu Hamasaki, Scott R. Evans, and Takashi Sozu. "Sizing clinical trials when comparing bivariate time-to-event outcomes." Statistics in Medicine 36, no. 9 (January 24, 2017): 1363–82. http://dx.doi.org/10.1002/sim.7225.
Full textDissertations / Theses on the topic "Time-to-event outcomes"
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Tudur, Smith Catrin. "Individual patient data meta-analysis with time-to-event outcomes." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406660.
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Cunha, de Sousa Ines Pereira Silva. "Analysis of Repeated Measurements and Time-to-Event Outcomes in Longitudinal Studies." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504199.
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Barthel, Friederike Maria-Sophie. "Issues in the design and analysis of clinical trials with time-to-event outcomes." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1445310/.
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Designers of clinical trials today face a number of different challenges. In a number of disease areas several treatments become available at any one time with only a limited number of patients available for investigation purposes. Furthermore, in disease areas such as HIV and cancer the pressure is high to find effective treatments quickly. Due to the recent advances in the human genome project more and more interaction effects between a treatment under study and the genetic make-up of a patient may be successfully analysed. This thesis aims to evaluate existing tools for the design and analysis of clinical trials with a time-to-event outcome and provide extensions in areas where existing tools do not perform satisfactorily. Particular emphasis is placed on sample size calculations for multi-arm and multi-stage trials and other complex mechanisms such as loss to follow-up and patient withdrawal from allocated treatment. Furthermore, advances are made in the area of treatment-covariate interactions, particularly in terms of analysis tools for such interactions.
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Dunphy, Marilyn Jane Myers. "An exploratory study to assess food behavior outcomes of a one- time nutrition intervention event." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44630.
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This research was conducted in an effort to substantiate the effect of nutrition counseling delivered at a local cholesterol screening clinic. It developed a method of measuring dietary habit changes conducive to a cholesterol- lowering diet. Hypercholesterolemic subjects were chosen for the study when their total blood cholesterol measured > 200 mg/dl from a Reflotron cholesterol screening device. At that time they were asked to fill out a dietary habit pre-test. Pre-tests from six subjects who did not receive nutrition counseling at the clinic were placed in the control group. Pre-tests from 15 subjects who received nutrition counseling at the clinic served as the test group.
Master of Science
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Sudell, M. E. "Methodology and software for joint modelling of time-to-event data and longitudinal outcomes across multiple studies." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3021706/.
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Thesis Title: Methodology and Software for Joint Modelling of Time-to-Event Data and Longitudinal Outcomes Across Multiple Studies Author: Maria Sudell Introduction and Aims: Univariate joint models for longitudinal and time-to-event data simultaneously model one outcome that is repeatedly measured over time, with another outcome which measures the time until the occurrence of an event. They have been increasingly used in the literature to account for dropout in longitudinal studies, to include time-varying covariates in time-to-event analyses, or to investigate links between longitudinal and time-to-event outcomes. Meta-analysis is the quantitative pooling of data from multiple studies. Such analyses can provide increased sample size and so detect small covariate effects. Modelling of multi-study data requires accounting for the clustering of individuals within studies and careful consideration of heterogeneity between studies. Research concerning methodology for modelling of joint longitudinal and time-to-event data in a multi-study or meta-analytic setting does not currently exist. This thesis develops novel methodologies and software for the modelling of multi-study joint longitudinal and time-to-event data. Methods: A review of current reporting standards of analyses applying joint modelling methodology to single study datasets, with a view to future Aggregate Data Meta-Analyses (AD-MA) of joint data is undertaken. Methodology for the one and two-stage Individual Participant Data Meta-Analyses (IPD-MA) are developed. A software package in the R language containing functionalities for various aspects of multi-study joint modelling analyses is built. The methodology and software is implemented in a real hypertension dataset, and also is tested in extensive simulation studies. Results: Reporting of model structure was amongst the areas identified for improvement in the reporting of joint models employed in single study applied analyses. Sufficient information was reported in the majority of studies for them to contribute to future AD-MA. Guidelines developed to ensure good quality two-stage IPD-MA of joint data were presented, designed to ensure only parameters with comparable interpretations are pooled. A range of one-stage models, each accounting for between study heterogeneity in varying ways, were described and applied to real data and simulation analyses. Models employing study level random effects were found unreliable for the investigated association structure, however fixed effect approaches or those that stratified baseline hazard by study were more reliable. The benefit of using joint models over separate time-to-event models in the presence of significant association between the longitudinal and time-to-event outcomes in both one and two-stage analyses was established. Novel software capable of one or two-stage analyses of large multi-study joint datasets was demonstrated in both the real data and simulation analyses. Conclusions: Reporting of joint modelling structure in single study applied analyses should be maintained and improved. Two-stage meta-analyses of joint modelling results should take care to pool only parameters with comparable interpretations. In meta-analyses, investigators should employ a joint modelling approach when association is known or suspected between the longitudinal and time-to-event outcomes. Further work into meta-analytic joint models is required to expand the range of available multi-study joint modelling structures, to allow for multivariate joint data, and to employ multivariate meta-analytic techniques in a two-stage meta-analysis.
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Campbell, Lucy Jane. "Statistical models for time to event outcomes and determination of causal relationships in an observational HIV/TB study." Thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/6570.
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Syed, Hamzah. "Design, evaluation and application of methodology and software for time-to-event outcomes in pharmacogenetic genome-wide association studies." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3027425/.
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Introduction and aims: Methodology and software for the analysis of genome-wide association studies (GWAS) have focused on binary phenotypes and quantitative traits. However, the impact of single nucleotide polymorphisms (SNPs) on time-to-event (TTE) outcomes is understudied, particularly for pharmacogenetic GWAS. Statistical methodology and computational tools to design and analyse GWAS with TTE outcomes are not well developed, due to the scale and complexity of data, particularly when analysing rare variants. This thesis aims to develop statistical methodology and a variety of computational tools to aid the design and analysis of both GWAS of common and rare variants with TTE outcomes. Methods: This thesis compares existing methodology such as the Cox proportional hazards, logistic and Weibull regression models using simulations based on a range of pharmacogenetic GWAS designs with TTE outcomes. This thesis also presents new statistical methodologies for the analysis of rare variants using a combination of gene-based tests of association and TTE regression models. Results: Examination of the literature provided an overview of the methods and software used for analysing GWAS with TTE outcomes. One approach taken due to lack of software availability was to dichotomise event times at a fixed time-point and analyse the binary outcome using existing GWAS software. A simulation study was conducted comparing alternative regression models under pharmacogenetic TTE study designs. This simulation study demonstrated that dichotomisation of the TTE outcome would result in a loss of statistical power. Hence, the thesis outlines three user-friendly computational tools specific to TTE GWAS. The first is SurvivalGWAS_Power, which performs power calculations and generates sample pharmacogenetic data across a range of design scenarios, allowing for censoring and interactions. Second, SurvivalGWAS_- SV, software capable of analysing large-scale imputed GWAS data, offering a variety of survival analysis models. Third, rareSurvival, a command line application, which implements gene-based burden tests for the analysis of rare variants with TTE outcomes. SurvivalGWAS_SV and rareSurvival have been evaluated through simulation studies as well as application to a GWAS investigating the pharmacogenetics of acute coronary syndrome (PhACS). The single variant and gene discovery analyses of the PhACS study identified novel loci associated with time to recurrence of a cardiovascular event including rs56045815 located in the CTNNA2 gene. Conclusions: This thesis introduces three novel computational tools for GWAS with TTE outcomes. SurvivalGWAS_SV and rareSurvival are compatible with highperformance computing clusters and are available on Linux, Windows and Mac OSX operating systems. SurvivalGWAS_SV and rareSurvival were applied to the PhACS data, identifying significantly associated SNPs and functional units for further followup. With their particular relevance to pharmacogenetic GWAS, SurvivalGWAS_Power, SurvivalGWAS_SV and rareSurvival, will help in the design of studies and identification of genetic biomarkers of patient response to treatment, with the ultimate goal of personalising therapeutic interventions.
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Köhler, Meike [Verfasser], and Sonja [Akademischer Betreuer] Greven. "Flexible Bayesian joint models for longitudinal biomarkers and time-to-event outcomes with applications to type 1 diabetes research / Meike Köhler ; Betreuer: Sonja Greven." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1142113728/34.
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Vipp, Oskarsson Robin, and Hampus Johansson. "Employee Motivation in the Event of Unexpected Change : The roles of time and uncertainty in employees’ adaptability to change." Thesis, Linnéuniversitetet, Institutionen för marknadsföring (MF), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-104470.
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The Covid-19 pandemic has made a major impact on organizations around the world since the outburst at the beginning of 2020. This has led the organization to let their employees work remotely from home. This situation has brought challenges for the employees which in turn have been forced to adapt to a new working environment. The uncertainty of the event may impact employee motivation. is to construct a model of not yet linked theoretical understandings that supports a simulation of potential future outcomes. Specifically, this paper draws a link between current understandings of employee motivation, employees’ adaptability to change. In order to simulate the current situation of the Covid-19 pandemic, this paper invites the notion of time and uncertainty into the equation. This to be able to demonstrate and understand how a new phenomenon can affect employees' motivation when they work from home for an extended period. The model proposes time as a non-self-healing process that instead risks impairing motivation if (a) self-regulatory activities are supporting the current motivation, and/or (b) the employee denies the change. In other words, there is no indication that the old saying 'time heals all wounds' fits in this context. In addition, the model indicates that the uncertainties derived from unexpected events drive employee's individual restraining forces. This paper contributes to the existing literature on employee motivation which previously lacked a framework for how motivation can be affected through unexpected change and extended work from home. This framework can also be used for future research where it will benefit from empirical data to further strengthen or develop the model.
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HO, CHUN-YING, and 何純瑩. "Bayesian phase II adaptive randomization by jointly modeling efficacy and toxicity as time-to-event outcomes." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/34n874.
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碩士東海大學
統計學系
105
In cancer study, the evidence of drug efficacy, such as tumor shrinkage, is typically observable after a relatively long period of time. In contrast, toxicity is often modeled as binary outcome. Such method ignores information on when the toxicity event occurs. Therefore, we propose a Bayesian adaptive randomization procedure that jointly model efficacy and toxicity as time-to-event outcomes for phase II trials. The frailties are used to induce the association between the bivariate outcomes. Moreover, we allow the randomization probability to depend on patients’ specific covariates. After filtering out of excessive toxicity or futility, we assign each new patient to the superior treatment arm. The simulation studies are conducted under different scenarios to examine the property of the proposed method, and compare it with the available Bayesian adaptive randomization procedures.
Books on the topic "Time-to-event outcomes"
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Saks, Alan M. Job Search and the School-to-Work Transition. Edited by Ute-Christine Klehe and Edwin van Hooft. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780199764921.013.008.
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The school-to-work transition (STWT) is a major life event for those who must leave behind their lives as full-time students and begin new lives as a full-time employees. Although much has been written about the STWT, the role and importance of job search has often been neglected. At the same time, research on job search has tended to treat the job-search process as an independent and isolated activity. In this chapter, I describe an integrated model of job search within the context of the STWT. It shows that job search is preceded by a career-planning and development stage and followed by a work-adjustment stage. A successful STWT requires students to engage in a number of behaviors at each stage which should result in numerous outcomes that are necessary for a successful transition to the next stage. The model shows that job search is a critical part of the STWT that connects the career-planning and development stage to the work-adjustment stage. The chapter concludes with a discussion of the implications of the model for job search and STWT research and practice.
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Healey, Richard. Causation and Locality. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198714057.003.0010.
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By moving to the context of relativistic space-time structure, this chapter completes the argument of Chapter 4 that we can use quantum theory locally to explain correlations that violate Bell inequalities with no instantaneous action at a distance. Chance here must be relativized not just to time but to a space-time point, so that an event may have more than one chance at the same time—it may even be certain relative to one space-time point but ‘at the same time’ completely uncertain relative to another. This renders Bell’s principle of Local Causality either inapplicable or intuitively unmotivated. Counterfactual dependence between the outcomes of measurements on systems assigned an entangled state is not causal since neither outcome is subject to intervention: but it may still be appealed to in a non-causal explanation of one in terms of the other.
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Eby, Lillian T., Melissa Mitchell, and Lauren Zimmerman. Work and Family in Times of Crisis. Edited by Tammy D. Allen and Lillian T. Eby. Oxford University Press, 2015. http://dx.doi.org/10.1093/oxfordhb/9780199337538.013.32.
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This chapter considers the effects of nonwork crises on the work–family interface. Drawing from Crisis Theory (Caplan, 1961, 1964), we develop a framework to understand how crisis events may affect work and family life over time. In so doing, we examine the short- and long-term work–family outcomes of crisis, and consider potential moderators of the associations between the experience of a crisis event and these outcomes. Next, we apply the framework to a number of exemplar nonwork crises internal and external to the individual and family, including addiction, relationship loss, natural disasters, and military deployment. We conclude by identifying research priorities related to understanding work and family in times of crisis.
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Douglas, Heather. Women, Intimate Partner Violence, and the Law. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190071783.001.0001.
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This book explores how women from diverse backgrounds interact with the law in response to intimate partner violence, over time. Every year, millions of women globally turn to law to help them live lives free and safe from violence. Women engage with child protection services and police. They apply for civil protection orders and family court orders to help them manage their children’s contact with a violent father, and take special visa pathways to avoid deportation following separation from an abuser. Women are often compelled to interact with law, through their abuser’s myriad legal applications against them. While separation may seem like a solution, it often accelerates legal engagement, providing new opportunities for continued abuse. Countless women who have experienced intimate partner violence are enmeshed in overlapping, complex, and often inconsistent legal processes. They have both fleeting and longer-term connections with legal system actors. Their stories demonstrate how abusers harness multiple aspects of the legal process, and its actors, to continue their abuse. They also highlight the regular failure of legal processes and actors to comprehend the significance of nonphysical abuse. Women show how legal system actors’ common expectation that separation is a single event, rather than a process, has implications for their connections with law and the outcomes they achieve. From time to time, the women in this study attained the safety and closure they sought from law, sometimes in circular and unexpected ways, but their narratives demonstrate the level of endurance, tenacity, and time this often required.
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Leys, Didier, Charlotte Cordonnier, and Valeria Caso. Stroke. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199687039.003.0067.
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Stroke is a major public health issue. Many are treatable in the acute stage, provided patients are admitted soon enough. The overall incidence of stroke in Western countries is approximately 2400 per year per million inhabitants, and 80% are due to cerebral ischaemia. The prevalence is approximately 12 000 per million inhabitants. Stroke is associated with increased long-term mortality, handicap, cognitive and behavioural impairments, recurrence, and an increased risk of other types of vascular events. It is of major interest to take the heterogeneity of stroke into account, because of differences in the acute management, secondary prevention, and outcomes, according to the subtype and cause of stroke. In all types of stroke, early epileptic seizures, delirium, increased intracranial pressure, and non-specific complications are frequent. In ischaemic strokes, specific complications, such as malignant infarcts, spontaneous haemorrhagic transformation, early recurrence, and a new ischaemic event in another vascular territory, are frequent. In haemorrhagic strokes, the major complication is the subsequent increased volume of bleeding. There is strong evidence that stroke patients should be treated in dedicated stroke units; each time 24 patients are treated in a stroke unit, instead of a conventional ward, one death and one dependence are prevented. This effect does not depend on age, severity, and the stroke subtype. For this reason, stroke unit care is the cornerstone of the treatment of stroke, aiming at the detection and management of life-threatening emergencies, stabilization of most physiological parameters, and prevention of early complications. In ischaemic strokes, besides this general management, specific therapies include intravenous recombinant tissue plasminogen activator, given as soon as possible and before 4.5 hours, otherwise aspirin 300 mg, immediately or after 24 hours in case of thrombolysis, and, in a few patients, decompressive surgery. In intracerebral haemorrhages, blood pressure lowering and haemostatic therapy, when needed, are the two targets, but surgery does not seem effective to reduce death and disability.
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Leys, Didier, Charlotte Cordonnier, and Valeria Caso. Stroke. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199687039.003.0067_update_001.
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Stroke is a major public health issue. Many are treatable in the acute stage, provided patients are admitted soon enough. The overall incidence of stroke in Western countries is approximately 2400 per year per million inhabitants, and 80% are due to cerebral ischaemia. The prevalence is approximately 12 000 per million inhabitants. Stroke is associated with increased long-term mortality, handicap, cognitive and behavioural impairments, recurrence, and an increased risk of other types of vascular events. It is of major interest to take the heterogeneity of stroke into account, because of differences in the acute management, secondary prevention, and outcomes, according to the subtype and cause of stroke. In all types of stroke, early epileptic seizures, delirium, increased intracranial pressure, and non-specific complications are frequent. In ischaemic strokes, specific complications, such as malignant infarcts, spontaneous haemorrhagic transformation, early recurrence, and a new ischaemic event in another vascular territory, are frequent. In haemorrhagic strokes, the major complication is the subsequent increased volume of bleeding. There is strong evidence that stroke patients should be treated in dedicated stroke units; each time 24 patients are treated in a stroke unit, instead of a conventional ward, one death and one dependence are prevented. This effect does not depend on age, severity, and the stroke subtype. For this reason, stroke unit care is the cornerstone of the treatment of stroke, aiming at the detection and management of life-threatening emergencies, stabilization of most physiological parameters, and prevention of early complications. In ischaemic strokes, besides this general management, specific therapies include intravenous recombinant tissue plasminogen activator, given as soon as possible and before 4.5 hours, otherwise aspirin 300 mg, immediately or after 24 hours in case of thrombolysis, and, in a few patients, decompressive surgery. In intracerebral haemorrhages, blood pressure lowering and haemostatic therapy, when needed, are the two targets, but surgery does not seem effective to reduce death and disability.
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Leys, Didier, Charlotte Cordonnier, and Valeria Caso. Stroke. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199687039.003.0067_update_002.
Full textAbstract:
Stroke is a major public health issue. Many are treatable in the acute stage, provided patients are admitted soon enough. The overall incidence of stroke in Western countries is approximately 2400 per year per million inhabitants, and 80% are due to cerebral ischaemia. The prevalence is approximately 12 000 per million inhabitants. Stroke is associated with increased long-term mortality, handicap, cognitive and behavioural impairments, recurrence, and an increased risk of other types of vascular events. It is of major interest to take the heterogeneity of stroke into account, because of differences in the acute management, secondary prevention, and outcomes, according to the subtype and cause of stroke. In all types of stroke, early epileptic seizures, delirium, increased intracranial pressure, and non-specific complications are frequent. In ischaemic strokes, specific complications, such as malignant infarcts, spontaneous haemorrhagic transformation, early recurrence, and a new ischaemic event in another vascular territory, are frequent. In haemorrhagic strokes, the major complication is the subsequent increased volume of bleeding. There is strong evidence that stroke patients should be treated in dedicated stroke units; each time 24 patients are treated in a stroke unit, instead of a conventional ward, one death and one dependence are prevented. This effect does not depend on age, severity, and the stroke subtype. For this reason, stroke unit care is the cornerstone of the treatment of stroke, aiming at the detection and management of life-threatening emergencies, stabilization of most physiological parameters, and prevention of early complications. In ischaemic strokes, besides this general management, specific therapies include intravenous recombinant tissue plasminogen activator, given as soon as possible and before 4.5 hours, mechanical thrombectomy in case of proximal occlusion (middle cerebral artery, intracranial internal carotid artery, basilar artery), on top of thrombolysis in the absence of contraindication or alone otherwise, aspirin 300 mg, immediately or after 24 hours in case of thrombolysis, and, in a few patients, decompressive surgery. In intracerebral haemorrhages, blood pressure lowering and haemostatic therapy, when needed, are the two targets, while surgery does not seem effective to reduce death and disability.
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Dow, Bonnie J. Making a Spectacle of the Movement. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252038563.003.0006.
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This chapter focuses on the Women's Strike for Equality on August 26, 1970. By this time, women's liberation seemed poised for its triumphal moment in the media spotlight. The House of Representatives had passed the Equal Rights Amendment a few weeks earlier, and all three networks had produced stories that linked this outcome to the movement's momentum. The strike seemed to confirm that momentum: involving tens of thousands of women in the United States and abroad, it was the subject of more national print and broadcast attention than any other feminist event that year. Despite the strike's inclusion of an array of liberal and radical feminist groups, it was an instance of media activism conceived and controlled by the National Organization for Women (NOW), and it put the organization's media pragmatism on full display. Confounding NOW's careful planning, the reports on the strike took an essentially liberal action and presented it as a radical one. Featuring almost no discussion of the three carefully chosen issues—abortion, equal pay, and child care—that the event was designed to dramatize, the network reports instead presented a narrative of feminist deviance, visually depicting the masses of women protestors as an entertaining spectacle.
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Brandeis, Daniel, Sandra K. Loo, Grainne McLoughlin, Hartmut Heinrich, and Tobias Banaschewski. Neurophysiology. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198739258.003.0009.
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Neurophysiology allows us to understand and modulate the neural mechanisms in ADHD with high time- and/or frequency-resolution. These non-invasive methods include electroencephalographic recordings at rest and during tasks, with spontaneous and event-related oscillations and potentials tracking covert processing and transcranial neuromodulation through magnetic or electric fields. The findings indicate consistent cognitive and neural deficits in ADHD related to impaired attention and deficient inhibition. Advanced signal processing and source imaging methods often converge with other imaging approaches. Neurophysiological findings also reveal considerable heterogeneity in ADHD regarding cognitive, affective, and genetic subtypes. This illustrates the importance of dimensional approaches and of pathophysiological mechanisms partly shared with other disorders. Although several potential neurophysiological markers of ADHD have been considered, a clinical use for individual diagnostics and classification is not supported to date. More research should clarify the clinical potential of multivariate multimodal classification and prediction of treatment outcome to advance individualized treatment.
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Bodart, Olivier, and Steven Laureys. Imaging the central nervous system in the critically ill. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0224.
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Imaging techniques play a major role in managing patients with acute severe neurological signs. Initial evaluation of patients with traumatic brain injuries is best performed with a computed tomography (CT) scan, both for its ability to demonstrate most of the significant lesions and for logistical reasons. Magnetic resonance imaging (MRI) is able to provide more subtle information, as well as prognosis indicators, but is impractical until the patient’s condition has been stabilized. MRI has the same advantages for assessing anoxic brain injuries. In strokes, MRI has become the technique of choice, as it is able to highlight new lesions among older ones, and can identify ischaemic lesions only a few minutes after the event. At the same time MRI can identify or exclude contraindications for intravenous thrombolysis. Subarachnoid haemorrhages are best initially assessed with CT followed by a digital suppression angiogram to identify arterial aneurysms or arteriovenous malformations. In spine imaging, CT scan works the best in indicating traumatic bone lesions, while MRI is unsurpassed in examining the spinal cord and ligamentous injuries, and can provide prognostic indicators of the expected functional outcome.
Book chapters on the topic "Time-to-event outcomes"
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Moore, Kelly L., and Mark J. van der Laan. "RCTs with Time-to-Event Outcomes." In Targeted Learning, 259–69. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9782-1_17.
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Stitelman, Ori M., and Mark J. van der Laan. "C-TMLE for Time-to-Event Outcomes." In Targeted Learning, 323–42. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9782-1_20.
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Tsiatis, Anastasios A., Marie Davidian, Shannon T. Holloway, and Eric B. Laber. "Regimes Based on Time-to-Event Outcomes." In Dynamic Treatment Regimes, 325–446. Boca Raton : Chapman and Hall/CRC, 2020. | Series: Chapman & Hall/CRC monographs on statistics and applied probability: Chapman and Hall/CRC, 2019. http://dx.doi.org/10.1201/9780429192692-8.
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Stitelman, Ori M., Victor De Gruttola, C. William Wester, and Mark J. van der Laan. "RCTs with Time-to-Event Outcomes and Effect Modification Parameters." In Targeted Learning, 271–98. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9782-1_18.
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Kieser, Meinhard. "Comparison of Two Groups for Time-to-Event Outcomes and Test for Difference or Superiority." In Springer Series in Pharmaceutical Statistics, 65–77. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-49528-2_6.
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Li, Linhong, Ren Zuo, Amanda Coston, Jeremy C. Weiss, and George H. Chen. "Neural Topic Models with Survival Supervision: Jointly Predicting Time-to-Event Outcomes and Learning How Clinical Features Relate." In Artificial Intelligence in Medicine, 371–81. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-59137-3_33.
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ter Wee, Marieke M., and Birgit I. Lissenberg-Witte. "Analyzing Time to Event Outcome Variables." In A Quick Guide on How to Conduct Medical Research, 115–49. Houten: Bohn Stafleu van Loghum, 2019. http://dx.doi.org/10.1007/978-90-368-2248-0_5.
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Lee, Rennie, and Sin Yi Cheung. "Refugee Children in Australia: Wellbeing and Integration." In Family Dynamics over the Life Course, 71–96. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-12224-8_5.
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AbstractWhether the children of immigrant populations, including refugees, integrate into the host society is a key challenge facing all countries with large immigrant populations. In Australia, this is crucial given rising numbers and anxieties over refugee settlement in recent decades. Forced migration and displacement due to violence, persecution, or natural disasters with families undertaking perilous journeys fleeing their homes often could mean a turning point and at the same time a stressful event that may have severe negative psychosocial and long-term effects. This can be particularly acute among refugee children, who are typically the least prepared to migrate, have experienced hardship associated with violence and persecution, and must grow up in a new country. From a life course perspective, the integration and wellbeing of refugee children is shaped by the timing and context of migration, including their age at migration and country of origin. In this chapter we draw on longitudinal data from Building a New Life in Australia (BNLA) to offer new evidence in our understanding of the integration and wellbeing of refugee children in Australia and policy recommendations to address the social disadvantages facing this population. Our findings indicate that refugee children are outperforming their parents, making intergenerational progress. However, we find some major differences by gender and national origin across a range of outcomes.
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Lee, Suhwan, Marco Comuzzi, and Xixi Lu. "Continuous Performance Evaluation for Business Process Outcome Monitoring." In Lecture Notes in Business Information Processing, 237–49. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-98581-3_18.
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AbstractWhile a few approaches to online predictive monitoring have focused on concept drift model adaptation, none have considered in depth the issue of performance evaluation for online process outcome prediction. Without such a continuous evaluation, users may be unaware of the performance of predictive models, resulting in inaccurate and misleading predictions. This paper fills this gap by proposing a framework for evaluating online process outcome predictions, comprising two different evaluation methods. These methods are partly inspired by the literature on streaming classification with delayed labels and complement each other to provide a comprehensive evaluation of process monitoring techniques: one focuses on real-time performance evaluation, i.e., evaluating the performance of the most recent predictions, whereas the other focuses on progress-based evaluation, i.e., evaluating the ability of a model to output correct predictions at different prefix lengths. We present an evaluation involving three publicly available event logs, including a log characterised by concept drift.
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Verboven, Sam, and Niels Martin. "Combining the Clinical and Operational Perspectives in Heterogeneous Treatment Effect Inference in Healthcare Processes." In Lecture Notes in Business Information Processing, 327–39. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-98581-3_24.
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AbstractRecent developments in causal machine learning open perspectives for new approaches that support decision-making in healthcare processes using causal models. In particular, Heterogeneous Treatment Effect (HTE) inference enables the estimation of causal treatment effects for individual cases, offering great potential in a process mining context. At the same time, HTE literature typically focuses on clinical outcome measures, disregarding process efficiency. This paper shows the potential of jointly considering the clinical and operational effects of treatments in the context of healthcare processes. Moreover, we present a simple pipeline that makes existing HTE machine learning techniques directly applicable to event logs. Besides these conceptual contributions, a proof-of-concept application starting from the publicly available sepsis event log is outlined, forming the basis for a critical reflection regarding HTE estimation in a process mining context.
Conference papers on the topic "Time-to-event outcomes"
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Capozzi, P., A. Psarra, V. Pachidis, and P. Pilidis. "A Finite Element Approach of Turbines in Contact Following a Shaft Failure Event." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23298.
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The shaft failure of a gas turbine engine can be considered as a potentially hazardous event. Since the turbine rotor becomes suddenly decoupled from the compressor, it will rapidly accelerate and disc bursting or blade shedding may be possible outcomes. Blade tangling occurring between the turbine blades and the downstream NGV stator vanes can be an effective mean to prevent dangerous over-speed conditions. Since experimental test arrangements are considered to be time and cost in-effective, impact simulations can aid the understanding of the main phenomena involved in the event and help the designer in reducing the possibility of dangerous over-speed conditions. This paper represents a first attempt to model the impact between turbines following a shaft failure event. The contribution of this paper is the modeling approach of turbines in contact after a shaft failure. The results of the impact simulation in terms of rotational speed, frictional torque and frictional energy are presented, while some basic checks of the FEA model are carried out to assess the plausibility of the derived results.
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Hawking, Paul, and Brendan McCarthy. "Integrating E-Learning Content into Enterprise Resource Planning (ERP) Curriculum." In InSITE 2004: Informing Science + IT Education Conference. Informing Science Institute, 2004. http://dx.doi.org/10.28945/2796.
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Enterprise Resource Planning (ERP) systems offer a software-based system that handles an enterprise’s total information system needs in an integrated fashion. Such systems have seen a significant growth in the last decade in the US, Europe and Australian markets and, more recently, increasing growth in Asian countries. This increase in demand for ERP systems in Asia offers opportunities for the provision of high-quality ERP education programs in the region. This paper describes the issues and barriers associated with integrating ERP systems into university curricula. It outlines the experiences of Victoria University in offering ERP education through a strategic alliance with SAP. The University is extending its offshore programs by offering ERP education in the region to take advantage of the current increase in demand in ERP applications. To assist with the delivery of offshore ERP education an ERP e-Learning model has been developed that integrates synchronous and asynchronous content. Asynchronous e-learning does not involve the presence of a teacher. Typically the learning content is located on a web server that students can access using the Internet. Synchronous e-learning requires the learner and teacher to be present in the event at the same time. It is a real-time, instructor-led online learning event in which all participants are available at the same time and can communicate directly with each other. The model uses four technologies to facilitate teaching: application service provision (ASP), web-CT, computer-based training and virtual classroom technology. The ERP e-learning model provides an innovative and efficient means to deliver ERP curriculum. It is able to provide greater flexibility in offshore subject delivery and to maximise student learning outcomes. This is particularly relevant in light of recent international medical (SARS) and terrorists incidents.
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Ugoyah, Joy, and Anita Mary Igbine. "Applications of AI and Data-Driven Modeling in Energy Production and Marketing Processes." In SPE Nigeria Annual International Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/207153-ms.
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Abstract Faster and more accurate decisions are what the Oil and Gas industry needs with the world's fast-evolving energy needs and economy. The area of Artificial intelligence and Data-driven modelling is relatively new and has not found popular application in the industry. AI is an emerging technology that can be used to predict event outcomes and automate anomaly-detection processes. The various applications of AI in different industries were researched into. This paper highlighted important processes that can be improved with the application of Artificial Intelligence through data-driven modelling. It also highlights areas in the various industries where AI intelligence is already being applied and ways it can be improved. AI and data-driven modelling has the potential to improve exploration accuracy, reduce production down-time, reduce cost of maintenance, and reduce health and safety risks. This body of information can serve as a guideline for adopting AI in the oil and gas industry. A trend of industry-tailored intelligence solutions would be more effective in the evolving energy industry.
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Raihanian Mashhadi, Ardeshir, and Sara Behdad. "Scheduling of Electronic Waste Collection Events." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59325.
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Despite recent efforts to alleviate the electronic waste (e-waste) problem, the product recovery management programs have not reached their full potential. The incompetency of the current e-waste recovery system mostly originates from the collection phase, where the consumers often have the tendency to keep their used electronics in storage rather than returning them. This may be due to lack of awareness about e-waste collection sites or the inconvenience of current e-waste collection infrastructure. To facilitate the collection of unwanted products, ‘e-waste collection’ events have been introduced for convenient and on-time disposal of electronic devices. However, factors such as consumer awareness, the volume of available e-waste for recovery, the resulting economic, environmental and social outcomes of those events, convenience of the location, laws and restrictions on the disposal of certain electronics, and the cost of holding such events make the scheduling a complicated decision, particularly for the remanufacturing industry. The purpose of this study is to characterize the e-waste collection scheduling problem and help decision makers determine the best schedule and characteristics of the e-waste event. An optimization framework has been developed to maximize the amount of collected e-waste.
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Ma, Qin, Lin Zeng, Shikui Tu, and Lei Xu. "Kernel Mean Matching with Mahalanobis Distance for Causal Inference of Time-to-event Outcome." In 2022 IEEE International Conference on Bioinformatics and Biomedicine (BIBM). IEEE, 2022. http://dx.doi.org/10.1109/bibm55620.2022.9995021.
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Schneider, Raymond E., Mathew C. Jacob, Michael T. Coon, Peter Niedermeier, and Jürgen Kaufmann. "An Advanced RCP Seal Design for Coping With Extended Loss of AC Power Event." In 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60303.
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The extended loss of AC power (ELAP) event can pose a significant challenge to the integrity of the Reactor Coolant System (RCS) in a Pressurized Water Reactor (PWR). To mitigate the consequences of this event, it is important to maintain adequate coolant inventory and the associated heat removal capability of the RCS. A critical RCS component in maintaining RCS inventory is the Reactor Coolant Pump (RCP) seals. To ensure seal integrity, the RCP seals are either independently cooled by back-up systems or are sufficiently robust to maintain their integrity without cooling until such time when cooling may be restored. A number of new RCP seal designs have been proposed by seal manufacturers to meet this challenge. This paper focuses on one such design, namely, the KSB Station Blackout (SBO) seal package. KSB RCP seals were first introduced in the nuclear industry in the 1970s. The original KSB RCP seals, designated as HDD-254 Type A, consisted of a three stage hydrodynamic design with each stage capable of retaining full RCS pressure. The Type A seals were initially installed in the Combustion Engineering (CE) Palo Verde units and in several reactors in Germany. In the 1980s, these seals were replaced with the Type C seals that incorporated several design improvements. These seals have been successfully installed and operated in over 100 RCPs in Europe, South America, South Korea, and China. These seals continue to demonstrate excellent operating experience with typical replacement interval of 4 to 6 years. Although the reliability of the Type C seals has been excellent based on operating experience, the seal was not specifically designed for coping with an ELAP event that might ensue following an SBO. In order to support the emerging needs of nuclear industry in response to Fukushima, KSB embarked on a seal design improvement program directed towards retaining the high operational reliability of the Type C seal while enhancing the RCP seal package’s high temperature coping capability. This activity resulted in a new seal package design that includes: (1) an advanced high temperature resistant, three stage, Type F seal, (2) a passive thermal check valve (PTCV) intended to passively isolate the RCP controlled bleed-off (CBO) line to maintain RCS inventory, and (3) a back-up fourth stage shaft seal called the “Stand-still” seal. This paper discusses the design and post-accident performance of KSB’s Type F hydrodynamic RCP seal package with emphasis on seal performance capabilities under ELAP conditions. The report concludes that the capability of the primary three stage hydrodynamic seals and the fourth stage “Stand-still” seal to function at high temperatures coupled with the reliable RCP CBO line closure capability and subsequent RCS depressurization ensures that any potential seal leakage would be held to a minimum (less than 2 gpm) for the duration of a 72 hour ELAP scenario. The ELAP coping strategies and their outcomes were validated by a seal test program conducted at KSB’s testing laboratories in Frankenthal, Germany. The results of the tests confirmed that the Type F seals exhibited extremely low leakage rates (∼0.01 gpm) at conditions representative of an ELAP scenario (120 hours up to 300 °C [572 °F] temperature and 160 barg [2320 psig] pressure).
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Sinha, Avick, Vaibhav Ramakrishnan, and Kathy Johnson. "Droplet Impact on a Curved Moving Liquid Film." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-79505.
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Abstract The European Commission has set targets to reduce the emissions of CO2 and NOx by 75% and 90% respectively, per passenger kilometre, by 2050. Computational modelling of elements within the aero-engine will play a key role in achieving this goal. Currently, the computational models used to characterise impact outcomes from droplets splashing on wall films in bearing chambers are based on correlations obtained for droplet impacts on plane films. The present study bridges that gap, being the first experimental study investigating droplet impact on a film moving on a curved surface. Experiments were conducted on a curved channel where the variation in the channel curvature provided the opportunity to investigate droplet impact at three different curvatures with three corresponding impact angles. Two droplet diameters of 2.34 mm and 1.90 mm were obtained using two different needle sizes attached to a syringe. The height of the syringe from the liquid film was varied to investigate the effect of droplet impact velocity. Five flow rates were considered to investigate the effect of film thickness on droplet impact. To investigate the dynamics of the droplet impact a high-speed imaging technique was used. Qualitatively, two different impingement outcomes were observed, namely, crown formation and crown splashing. The key difference between the two outcomes is in the production of secondary droplets from the crown in crown splashing. Quantitatively, it was observed that at lower angles of impingement (less oblique), the transition from crown formation to crown splashing agrees strongly with previous literature for impact on static films and films on an angled plane where the transition value of the splashing parameter is 2100 based on the absolute velocity of the droplet. At the higher angles of impingement (more oblique), the critical splashing parameter (K) value was found to increase, as with droplet impact on an inclined surface or liquid film, but to a significantly higher value (2800 at 38°) than was typically obtained for an inclined plane (2400 at comparable angle). This indicates that the transition from crown formation to splashing at the highest radius of curvature is different to that of inclined planes at higher angles. Investigating impact event duration, the present study suggests that with the increase in the impact energy, the time required for the film to come back to its original state increases.
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Mitchell, Antony J., David Hann, and Kathy Simmons. "Experimental Investigation Into Crater Morphology for Droplets Impinging on a Moving Film." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63443.
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The behaviour of impinging droplets is a field that has been studied for over 100 years mostly focused on impingements upon solid substrates or static films. Few studies report cases when the moving film might influence the impact outcomes. In many situations where droplet impact is industrially relevant there is film motion and relying on observations and correlations for impacts on static films might not be reliable. The University of Nottingham’s Gas Turbine and Transmissions Research Centre is conducting a research program investigating impact outcomes and crater morphology for water droplets of around 2–3 mm falling under the influence of gravity and impacting on films created by water flow down an inclined plane. In the investigation reported here dimensionless film heights were in the range 0.77 to 1.8 and the plane was inclined at 10° to the horizontal. This paper details the investigation into the morphology of the crater formed during an impingement event. The properties of the impinging droplet are measured using a high-speed camera to provide a side-view of the impingement. Brightness-Based Laser-Induced Fluorescence (BB-LIF) is used to provide three-dimensional measurements of the crater during the self-similar inertial regime. This is accomplished by doping the fluid with Rhodamine 6G, and exciting the fluorescence with a 527 nm pulsed Nd-Yag laser. A second high-speed camera observes the impingement from below in order to provide information about the behaviour of the film. The development of cavity depth is compared to published models from work on both deep and thin static films. Further, the development of cavity width with time is compared against existing models from static film research. A modification to these models is proposed that includes the effects of film velocity. The effect of film movement on the cavity footprint is examined; both the equivalent radius and the cavity width are investigated and the differences compared to static film experiments are quantified. Some modifications to an established width model are suggested, and an effect of droplet diameter upon this cavity width is noted. The work shows that static film models are not universally applicable for moving films.
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Cung, Khanh, Toby Rockstroh, Stephen Ciatti, William Cannella, and S. Scott Goldsborough. "Parametric Study of Ignition and Combustion Characteristics From a Gasoline Compression Ignition Engine Using Two Different Reactivity Fuels." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9395.
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Unlike homogeneous charge compression ignition (HCCI) that has the complexity in controlling the start of combustion event, partially premixed combustion (PPC) provides the flexibility of defining the ignition timing and combustion phasing with respect to the time of injection. In PPC, the stratification of the charge can be influenced by a variety of methods such as number of injections (single or multiple injections), injection pressure, injection timing (early to near TDC injection), intake boost pressure, or combination of several factors. The current study investigates the effect of these factors when testing two gasoline-like fuels of different reactivity (defined by Research Octane Number or RON) in a 1.9-L inline 4-cylinder diesel engine. From the collection of engine data, a full factorial analysis was created in order to identify the factors that most influence the outcomes such as the location of ignition, combustion phasing, combustion stability, and emissions. Furthermore, the interaction effect of combinations of two factors or more was discussed with the implication of fuel reactivity under current operating conditions. The analysis was done at both low (1000 RPM) and high speed (2000 RPM). It was found that the boost pressure and air/fuel ratio have strong impact on ignition and combustion phasing. Finally, injection-timing sweeps were conducted whereby the ignition (CA10) of the two fuels with significantly different reactivity were matched by controlling the boost pressure while maintaining a constant lambda (air/fuel equivalence ratio).
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Popa, Andrei, Ben Amaba, and Jeff Daniels. "A Framework of Best Practices for Delivering Successful Artificial Intelligence Projects. A Case Study Demonstration." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206014-ms.
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Abstract A practical framework that outlines the critical steps of a successful process that uses data, machine learning (Ml), and artificial intelligence (AI) is presented in this study. A practical case study is included to demonstrate the process. The use of artificial intelligent and machine learning has not only enhanced but also sped up problem-solving approaches in many domains, including the oil and gas industry. Moreover, these technologies are revolutionizing all key aspects of engineering including; framing approaches, techniques, and outcomes. The proposed framework includes key components to ensure integrity, quality, and accuracy of data and governance centered on principles such as responsibility, equitability, and reliability. As a result, the industry documentation shows that technology coupled with process advances can improve productivity by 20%. A clear work-break-down structure (WBS) to create value using an engineering framework has measurable outcomes. The AI and ML technologies enable the use of large amounts of information, combining static & dynamic data, observations, historical events, and behaviors. The Job Task Analysis (JTA) model is a proven framework to manage processes, people, and platforms. JTA is a modern data-focused approach that prioritizes in order: problem framing, analytics framing, data, methodology, model building, deployment, and lifecycle management. The case study exemplifies how the JTA model optimizes an oilfield production plant, similar to a manufacturing facility. A data-driven approach was employed to analyze and evaluate the production fluid impact during facility-planned or un-planned system disruptions. The workflows include data analytics tools such as ML&AI for pattern recognition and clustering for prompt event mitigation and optimization. The paper demonstrates how an integrated framework leads to significant business value. The study integrates surface and subsurface information to characterize and understand the production impact due to planned and unplanned plant events. The findings led to designing a relief system to divert the back pressure during plant shutdown. The study led to cost avoidance of a new plant, saving millions of dollars, environment impact, and safety considerations, in addition to unnecessary operating costs and maintenance. Moreover, tens of millions of dollars value per year by avoiding production loss of plant upsets or shutdown was created. The study cost nothing to perform, about two months of not focused time by a team of five engineers and data scientists. The work provided critical steps in "creating a trusting" model and "explainability’. The methodology was implemented using existing available data and tools; it was the process and engineering knowledge that led to the successful outcome. Having a systematic WBS has become vital in data analytics projects that use AI and ML technologies. An effective governance system creates 25% productivity improvement and 70% capital improvement. Poor requirements can consume 40%+ of development budget. The process, models, and tools should be used on engineering projects where data and physics are present. The proposed framework demonstrates the business impact and value creation generated by integrating models, data, AI, and ML technologies for modeling and optimization. It reflects the collective knowledge and perspectives of diverse professionals from IBM, Lockheed Martin, and Chevron, who joined forces to document a standard framework for achieving success in data analytics/AI projects.
Reports on the topic "Time-to-event outcomes"
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Treadwell, Jonathan R., James T. Reston, Benjamin Rouse, Joann Fontanarosa, Neha Patel, and Nikhil K. Mull. Automated-Entry Patient-Generated Health Data for Chronic Conditions: The Evidence on Health Outcomes. Agency for Healthcare Research and Quality (AHRQ), March 2021. http://dx.doi.org/10.23970/ahrqepctb38.
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Background. Automated-entry consumer devices that collect and transmit patient-generated health data (PGHD) are being evaluated as potential tools to aid in the management of chronic diseases. The need exists to evaluate the evidence regarding consumer PGHD technologies, particularly for devices that have not gone through Food and Drug Administration evaluation. Purpose. To summarize the research related to automated-entry consumer health technologies that provide PGHD for the prevention or management of 11 chronic diseases. Methods. The project scope was determined through discussions with Key Informants. We searched MEDLINE and EMBASE (via EMBASE.com), In-Process MEDLINE and PubMed unique content (via PubMed.gov), and the Cochrane Database of Systematic Reviews for systematic reviews or controlled trials. We also searched ClinicalTrials.gov for ongoing studies. We assessed risk of bias and extracted data on health outcomes, surrogate outcomes, usability, sustainability, cost-effectiveness outcomes (quantifying the tradeoffs between health effects and cost), process outcomes, and other characteristics related to PGHD technologies. For isolated effects on health outcomes, we classified the results in one of four categories: (1) likely no effect, (2) unclear, (3) possible positive effect, or (4) likely positive effect. When we categorized the data as “unclear” based solely on health outcomes, we then examined and classified surrogate outcomes for that particular clinical condition. Findings. We identified 114 unique studies that met inclusion criteria. The largest number of studies addressed patients with hypertension (51 studies) and obesity (43 studies). Eighty-four trials used a single PGHD device, 23 used 2 PGHD devices, and the other 7 used 3 or more PGHD devices. Pedometers, blood pressure (BP) monitors, and scales were commonly used in the same studies. Overall, we found a “possible positive effect” of PGHD interventions on health outcomes for coronary artery disease, heart failure, and asthma. For obesity, we rated the health outcomes as unclear, and the surrogate outcomes (body mass index/weight) as likely no effect. For hypertension, we rated the health outcomes as unclear, and the surrogate outcomes (systolic BP/diastolic BP) as possible positive effect. For cardiac arrhythmias or conduction abnormalities we rated the health outcomes as unclear and the surrogate outcome (time to arrhythmia detection) as likely positive effect. The findings were “unclear” regarding PGHD interventions for diabetes prevention, sleep apnea, stroke, Parkinson’s disease, and chronic obstructive pulmonary disease. Most studies did not report harms related to PGHD interventions; the relatively few harms reported were minor and transient, with event rates usually comparable to harms in the control groups. Few studies reported cost-effectiveness analyses, and only for PGHD interventions for hypertension, coronary artery disease, and chronic obstructive pulmonary disease; the findings were variable across different chronic conditions and devices. Patient adherence to PGHD interventions was highly variable across studies, but patient acceptance/satisfaction and usability was generally fair to good. However, device engineers independently evaluated consumer wearable and handheld BP monitors and considered the user experience to be poor, while their assessment of smartphone-based electrocardiogram monitors found the user experience to be good. Student volunteers involved in device usability testing of the Weight Watchers Online app found it well-designed and relatively easy to use. Implications. Multiple randomized controlled trials (RCTs) have evaluated some PGHD technologies (e.g., pedometers, scales, BP monitors), particularly for obesity and hypertension, but health outcomes were generally underreported. We found evidence suggesting a possible positive effect of PGHD interventions on health outcomes for four chronic conditions. Lack of reporting of health outcomes and insufficient statistical power to assess these outcomes were the main reasons for “unclear” ratings. The majority of studies on PGHD technologies still focus on non-health-related outcomes. Future RCTs should focus on measurement of health outcomes. Furthermore, future RCTs should be designed to isolate the effect of the PGHD intervention from other components in a multicomponent intervention.