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Sample records for parametric competing risks

  1. Parametric Estimation in a Recurrent Competing Risks Model

    PubMed Central

    Peña, Edsel A.

    2014-01-01

    A resource-efficient approach to making inferences about the distributional properties of the failure times in a competing risks setting is presented. Efficiency is gained by observing recurrences of the competing risks over a random monitoring period. The resulting model is called the recurrent competing risks model (RCRM) and is coupled with two repair strategies whenever the system fails. Maximum likelihood estimators of the parameters of the marginal distribution functions associated with each of the competing risks and also of the system lifetime distribution function are presented. Estimators are derived under perfect and partial repair strategies. Consistency and asymptotic properties of the estimators are obtained. The estimation methods are applied to a data set of failures for cars under warranty. Simulation studies are used to ascertain the small sample properties and the efficiency gains of the resulting estimators. PMID:25346751

  2. Parametric mixture models to evaluate and summarize hazard ratios in the presence of competing risks with time-dependent hazards and delayed entry

    PubMed Central

    Lau, Bryan; Cole, Stephen R.; Gange, Stephen J.

    2010-01-01

    In the analysis of survival data, there are often competing events that preclude an event of interest from occurring. Regression analysis with competing risks is typically undertaken using a cause-specific proportional hazards model. However, modern alternative methods exist for the analysis of the subdistribution hazard with a corresponding subdistribution proportional hazards model. In this paper, we introduce a flexible parametric mixture model as a unifying method to obtain estimates of the cause-specific and subdistribution hazards and hazard ratio functions. We describe how these estimates can be summarized over time to give a single number that is comparable to the hazard ratio that is obtained from a corresponding cause-specific or subdistribution proportional hazards model. An application to the Women’s Interagency HIV Study is provided to investigate injection drug use and the time to either the initiation of effective antiretroviral therapy, or clinical disease progression as a competing event. PMID:21337360

  3. Prediction of long-term cumulative incidences based on short-term parametric model for competing risks: application in early breast cancer.

    PubMed

    Cabarrou, B; Belin, L; Somda, S M; Falcou, M C; Pierga, J Y; Kirova, Y; Delord, J P; Asselain, B; Filleron, T

    2016-04-01

    Use of parametric statistical models can be a solution to reduce the follow-up period time required to estimate long-term survival. Mould and Boag were the first to use the lognormal model. Competing risks methodology seems more suitable when a particular event type is of interest than classical survival analysis. The objective was to evaluate the ability of the Jeong and Fine model to predict long-term cumulative incidence. Survival data recorded by Institut Curie (Paris) from 4761 breast cancer patients treated and followed between 1981 and 2013 were used. Long-term cumulative incidence rates predicted by the model using short-term follow-up data were compared to non-parametric estimation using complete follow-up data. 20- or 25-year cumulative incidence rates for loco-regional recurrence and distant metastasis predicted by the model using a maximum of 10 years of follow-up data had a maximum difference of around 6 % compared to non-parametric estimation. Prediction rates were underestimated for the third and composite event (contralateral or second cancer or death). Predictive ability of Jeong and Fine model on breast cancer data was generally good considering the short follow-up period time used for the estimation especially when a proportion of patient did not experience loco-regional recurrence or distant metastasis. PMID:27075918

  4. Recursive Partitioning Method on Competing Risk Outcomes

    PubMed Central

    Xu, Wei; Che, Jiahua; Kong, Qin

    2016-01-01

    In some cancer clinical studies, researchers have interests to explore the risk factors associated with competing risk outcomes such as recurrence-free survival. We develop a novel recursive partitioning framework on competing risk data for both prognostic and predictive model constructions. We define specific splitting rules, pruning algorithm, and final tree selection algorithm for the competing risk tree models. This methodology is quite flexible that it can corporate both semiparametric method using Cox proportional hazards model and parametric competing risk model. Both prognostic and predictive tree models are developed to adjust for potential confounding factors. Extensive simulations show that our methods have well-controlled type I error and robust power performance. Finally, we apply both Cox proportional hazards model and flexible parametric model for prognostic tree development on a retrospective clinical study on oropharyngeal cancer patients. PMID:27486300

  5. Nonparametric estimation with recurrent competing risks data

    PubMed Central

    Peña, Edsel A.

    2014-01-01

    Nonparametric estimators of component and system life distributions are developed and presented for situations where recurrent competing risks data from series systems are available. The use of recurrences of components’ failures leads to improved efficiencies in statistical inference, thereby leading to resource-efficient experimental or study designs or improved inferences about the distributions governing the event times. Finite and asymptotic properties of the estimators are obtained through simulation studies and analytically. The detrimental impact of parametric model misspecification is also vividly demonstrated, lending credence to the virtue of adopting nonparametric or semiparametric models, especially in biomedical settings. The estimators are illustrated by applying them to a data set pertaining to car repairs for vehicles that were under warranty. PMID:24072583

  6. Familial Risk and Child Competence.

    ERIC Educational Resources Information Center

    Sameroff, Arnold J.; Seifer, Ronald

    1983-01-01

    Examines components of familial risk in the context of a four-year longitudinal study of children with mentally ill mothers. Risk factors examined were parental mental health, social status, parental perspectives, and family stress. Interactions among risk factors were found to be complex and different for cognitive and social-emotional…

  7. ANALYSIS OF LAMB MORTALITY USING COMPETING RISKS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A competing risks model was used to describe lamb mortality up to four weeks of age in a composite sheep flock with 8,642 lamb records. Discrete survival methods were applied using sire and animal models. The results indicated that substantial variation exists in the risk of lambs dying from diffe...

  8. Risks, risk assessment and risk competence in toxicology

    PubMed Central

    Stahlmann, Ralf; Horvath, Aniko

    2015-01-01

    Understanding the toxic effects of xenobiotics requires sound knowledge of physiology and biochemistry. The often described lack of understanding pharmacology/toxicology is therefore primarily caused by the general absence of the necessary fundamental knowledge. Since toxic effects depend on exposure (or dosage) assessing the risks arising from toxic substances also requires quantitative reasoning. Typically public discussions nearly always neglect quantitative aspects and laypersons tend to disregard dose-effect-relationships. One of the main reasons for such disregard is the fact that exposures often occur at extremely low concentrations that can only be perceived intellectually but not by the human senses. However, thresholds in the low exposure range are often scientifically disputed. At the same time, ignorance towards known dangers is wide-spread. Thus, enhancing the risk competence of laypersons will have to be initially restricted to increasing the awareness of existing problems. PMID:26195922

  9. Creating Efficient Instrumentation Networks to Support Parametric Risk Transfer

    NASA Astrophysics Data System (ADS)

    Rockett, P.

    2009-04-01

    The development and institutionalisation of Catastrophe modelling during the 1990s opened the way for Catastrophe risk securitization transactions in which catastrophe risk held by insurers is transferred to the capital markets in the form of a bond. Cat Bonds have been one of the few areas of the capital markets in which the risk modelling has remained secure and the returns on the bonds have held up well through the 2008 Credit Crunch. There are three ways of structuring the loss triggers on bonds: ‘indemnity triggers' - reflecting the actual losses to the issuers; ‘index triggers' reflecting the losses to some index such as reported insurance industry loss and ‘parametric triggers' reflecting the parameters of the underlying catastrophe event itself. Indemnity triggers require that the investors trust that the insurer is reporting all their underlying exposures, while both indemnity and index losses may take 1-2 years to settle before all the claims are reported and resolved. Therefore parametric structures have many advantages, in particular in that the bond can be settled rapidly after an event. The challenge is to create parametric indices that closely reflect the actual losses to the insurer - ie that minimise ‘basis risk'. First generation parametric indices had high basis risk as they were crudely based on the magnitude of an earthquake occurring within some defined geographical box, or the intensity of a hurricane relative to the distance of the storm from some location. Second generation triggers involve taking measurements of ground motion or windspeed or flood depths at many locations and weighting each value so that the overall index closely mimics insurance loss. Cat bonds with second generation parametric triggers have been successfully issued for European Windstorm, UK Flood and California and Japan Earthquake. However the spread of second generation parametric structures is limited by the availability of suitable networks of

  10. Competing Risk Regression Models for Epidemiologic Data

    PubMed Central

    Cole, Stephen R.; Gange, Stephen J.

    2009-01-01

    Competing events can preclude the event of interest from occurring in epidemiologic data and can be analyzed by using extensions of survival analysis methods. In this paper, the authors outline 3 regression approaches for estimating 2 key quantities in competing risks analysis: the cause-specific relative hazard (csRH) and the subdistribution relative hazard (sdRH). They compare and contrast the structure of the risk sets and the interpretation of parameters obtained with these methods. They also demonstrate the use of these methods with data from the Women's Interagency HIV Study established in 1993, treating time to initiation of highly active antiretroviral therapy or to clinical disease progression as competing events. In our example, women with an injection drug use history were less likely than those without a history of injection drug use to initiate therapy prior to progression to acquired immunodeficiency syndrome or death by both measures of association (csRH = 0.67, 95% confidence interval: 0.57, 0.80 and sdRH = 0.60, 95% confidence interval: 0.50, 0.71). Moreover, the relative hazards for disease progression prior to treatment were elevated (csRH = 1.71, 95% confidence interval: 1.37, 2.13 and sdRH = 2.01, 95% confidence interval: 1.62, 2.51). Methods for competing risks should be used by epidemiologists, with the choice of method guided by the scientific question. PMID:19494242

  11. Minimization of Basis Risk in Parametric Earthquake Cat Bonds

    NASA Astrophysics Data System (ADS)

    Franco, G.

    2009-12-01

    A catastrophe -cat- bond is an instrument used by insurance and reinsurance companies, by governments or by groups of nations to cede catastrophic risk to the financial markets, which are capable of supplying cover for highly destructive events, surpassing the typical capacity of traditional reinsurance contracts. Parametric cat bonds, a specific type of cat bonds, use trigger mechanisms or indices that depend on physical event parameters published by respected third parties in order to determine whether a part or the entire bond principal is to be paid for a certain event. First generation cat bonds, or cat-in-a-box bonds, display a trigger mechanism that consists of a set of geographic zones in which certain conditions need to be met by an earthquake’s magnitude and depth in order to trigger payment of the bond principal. Second generation cat bonds use an index formulation that typically consists of a sum of products of a set of weights by a polynomial function of the ground motion variables reported by a geographically distributed seismic network. These instruments are especially appealing to developing countries with incipient insurance industries wishing to cede catastrophic losses to the financial markets because the payment trigger mechanism is transparent and does not involve the parties ceding or accepting the risk, significantly reducing moral hazard. In order to be successful in the market, however, parametric cat bonds have typically been required to specify relatively simple trigger conditions. The consequence of such simplifications is the increase of basis risk. This risk represents the possibility that the trigger mechanism fails to accurately capture the actual losses of a catastrophic event, namely that it does not trigger for a highly destructive event or vice versa, that a payment of the bond principal is caused by an event that produced insignificant losses. The first case disfavors the sponsor who was seeking cover for its losses while the

  12. Competing hazards with shared unmeasured risk factors.

    PubMed

    Hill, D H; Axinn, W G; Thornton, A

    1993-01-01

    "The present paper develops a generalization of the standard discrete-time competing hazards model that allows for the types of stochastic dependencies resulting from shared unmeasured risk factors. An empirical example is provided using the process by which young women form their first conjugal residential union, with married and unmarried cohabitation representing the competing alternatives. The results suggest considerable and significant similarity of the alternatives in terms of the unmeasurables. It is also shown that, as a result, the independence assumption leads to substantially biased estimates of the net marriage and net cohabitation survival functions." The data concern a cohort of white children born in Detroit, Michigan, in 1961 and their mothers, followed up to 1985. PMID:12318164

  13. Incorporating Classification Uncertainty in Competing- risks Nest- failure Analysis

    EPA Science Inventory

    Nesting birds risk nest failure due to many causes. Though partitioning risk of failure among causes has long been of interest to ornithologists, formal methods for estimating competing risk have been lacking.

  14. Multi-parametric prediction for cardiovascular risk assessment.

    PubMed

    Henriques, Jorge; de Carvalho, Paulo; Rocha, Teresa; Paredes, Simão; Morais, João

    2016-01-01

    The employment of personal health systems (pHealth) is a valuable concept in the management of chronic diseases, particularly in the context of cardiovascular diseases. By means of a continuous monitoring of the patient it is possible to seamless access multiple sources of data, including physiological signals, providing professionals with a global and reliable view of the patient's status. In practice, it is possible the prompt diagnosis of events, the early prediction of critical events and the implementation of personalized therapies. Furthermore, the information collected during long periods creates new opportunities in the diagnosis of a disease, in its evolution, and in the prediction of possible complications. The focus of this work is the research and implementation of multi-parametric algorithms for data analysis in pHealth context, including data mining techniques as well as physiological signal modelling and processing. In particular, fusion strategies for cardiovascular status evaluation (namely cardiovascular risk assessment and cardiac function estimation) and multi-parametric prediction algorithms for the early detection of cardiovascular events (such as hypertension, syncope and heart failure decompensation) will be addressed. PMID:27225547

  15. Ohio Financial Services and Risk Management. Technical Competency Profile (TCP).

    ERIC Educational Resources Information Center

    Ray, Gayl M.; Wilson, Nick; Mangini, Rick

    This document describes the essential competencies from secondary through post-secondary associate degree programs for a career in financial services and risk management. Ohio College Tech Prep Program standards are described, and a key to profile codes is provided. Sample occupations in this career area, such as financial accountant, loan…

  16. Decision-making competence predicts domain-specific risk attitudes.

    PubMed

    Weller, Joshua A; Ceschi, Andrea; Randolph, Caleb

    2015-01-01

    Decision-making competence (DMC) reflects individual differences in rational responding across several classic behavioral decision-making tasks. Although it has been associated with real-world risk behavior, less is known about the degree to which DMC contributes to specific components of risk attitudes. Utilizing a psychological risk-return framework, we examined the associations between risk attitudes and DMC. Italian community residents (n = 804) completed an online DMC measure, using a subset of the original Adult-DMC battery. Participants also completed a self-reported risk attitude measure for three components of risk attitudes (risk-taking, risk perceptions, and expected benefits) across six risk domains. Overall, greater performance on the DMC component scales were inversely, albeit modestly, associated with risk-taking tendencies. Structural equation modeling results revealed that DMC was associated with lower perceived expected benefits for all domains. In contrast, its association with perceived risks was more domain-specific. These analyses also revealed stronger indirect effects for the DMC → expected benefits → risk-taking path than the DMC → perceived riskrisk-taking path, especially for behaviors that may be considered more maladaptive in nature. These results suggest that DMC performance differentially impacts specific components of risk attitudes, and may be more strongly related to the evaluation of expected value of a specific behavior. PMID:26029128

  17. Decision-making competence predicts domain-specific risk attitudes

    PubMed Central

    Weller, Joshua A.; Ceschi, Andrea; Randolph, Caleb

    2015-01-01

    Decision-making competence (DMC) reflects individual differences in rational responding across several classic behavioral decision-making tasks. Although it has been associated with real-world risk behavior, less is known about the degree to which DMC contributes to specific components of risk attitudes. Utilizing a psychological risk-return framework, we examined the associations between risk attitudes and DMC. Italian community residents (n = 804) completed an online DMC measure, using a subset of the original Adult-DMC battery. Participants also completed a self-reported risk attitude measure for three components of risk attitudes (risk-taking, risk perceptions, and expected benefits) across six risk domains. Overall, greater performance on the DMC component scales were inversely, albeit modestly, associated with risk-taking tendencies. Structural equation modeling results revealed that DMC was associated with lower perceived expected benefits for all domains. In contrast, its association with perceived risks was more domain-specific. These analyses also revealed stronger indirect effects for the DMC → expected benefits → risk-taking path than the DMC → perceived riskrisk-taking path, especially for behaviors that may be considered more maladaptive in nature. These results suggest that DMC performance differentially impacts specific components of risk attitudes, and may be more strongly related to the evaluation of expected value of a specific behavior. PMID:26029128

  18. Societal perspectives on risk awareness and risk competence.

    PubMed

    Koller, Michael; Hoffrage, Ulrich

    2015-01-01

    Medical risks can be assessed by objectifiable therapeutic features; however, these risks are also characterised to a considerable degree by individual and social values. People tend to strive towards both freedom as well as safety; in a medical context, these two aims are taken into account by shared decision-making models and by stricter regulations in the pharmaceutical sector. Media reports on medical risks are caught between providing information and economic interests, and this conflict particularly complicates rational discussions about unexpected risks (for instance, in the field of natural medicine). Thus, it is necessary to create the type of information culture which allows differentiating between real and less pronounced risks. PMID:26195921

  19. Societal perspectives on risk awareness and risk competence

    PubMed Central

    Koller, Michael; Hoffrage, Ulrich

    2015-01-01

    Medical risks can be assessed by objectifiable therapeutic features; however, these risks are also characterised to a considerable degree by individual and social values. People tend to strive towards both freedom as well as safety; in a medical context, these two aims are taken into account by shared decision-making models and by stricter regulations in the pharmaceutical sector. Media reports on medical risks are caught between providing information and economic interests, and this conflict particularly complicates rational discussions about unexpected risks (for instance, in the field of natural medicine). Thus, it is necessary to create the type of information culture which allows differentiating between real and less pronounced risks. PMID:26195921

  20. Smoking, death, and Alzheimer disease: a case of competing risks.

    PubMed

    Chang, Chung-Chou H; Zhao, Yongyun; Lee, Ching-Wen; Ganguli, Mary

    2012-01-01

    If smoking is a risk factor for Alzheimer disease (AD) but a smoker dies of another cause before developing or manifesting AD, smoking-related mortality may mask the relationship between smoking and AD. This phenomenon, referred to as competing risk, complicates efforts to model the effect of smoking on AD. Typical survival regression models assume that censorship from analysis is unrelated to an individual's probability for developing AD (ie, censoring is noninformative). However, if individuals who die before developing AD are younger than those who survive long enough to develop AD, and if they include a higher percentage of smokers than nonsmokers, the incidence of AD will appear to be higher in older individuals and in nonsmokers. Further, age-specific mortality rates are higher in smokers because they die earlier than nonsmokers. Therefore, if we fail to take into account the competing risk of death when we estimate the effect of smoking on AD, we bias the results and are in fact only comparing the incidence of AD in nonsmokers with that in the healthiest smokers. In this study, we demonstrate that the effect of smoking on AD differs in models that are and are not adjusted for competing risks. PMID:22185783

  1. Crash risk analysis for Shanghai urban expressways: A Bayesian semi-parametric modeling approach.

    PubMed

    Yu, Rongjie; Wang, Xuesong; Yang, Kui; Abdel-Aty, Mohamed

    2016-10-01

    Urban expressway systems have been developed rapidly in recent years in China; it has become one key part of the city roadway networks as carrying large traffic volume and providing high traveling speed. Along with the increase of traffic volume, traffic safety has become a major issue for Chinese urban expressways due to the frequent crash occurrence and the non-recurrent congestions caused by them. For the purpose of unveiling crash occurrence mechanisms and further developing Active Traffic Management (ATM) control strategies to improve traffic safety, this study developed disaggregate crash risk analysis models with loop detector traffic data and historical crash data. Bayesian random effects logistic regression models were utilized as it can account for the unobserved heterogeneity among crashes. However, previous crash risk analysis studies formulated random effects distributions in a parametric approach, which assigned them to follow normal distributions. Due to the limited information known about random effects distributions, subjective parametric setting may be incorrect. In order to construct more flexible and robust random effects to capture the unobserved heterogeneity, Bayesian semi-parametric inference technique was introduced to crash risk analysis in this study. Models with both inference techniques were developed for total crashes; semi-parametric models were proved to provide substantial better model goodness-of-fit, while the two models shared consistent coefficient estimations. Later on, Bayesian semi-parametric random effects logistic regression models were developed for weekday peak hour crashes, weekday non-peak hour crashes, and weekend non-peak hour crashes to investigate different crash occurrence scenarios. Significant factors that affect crash risk have been revealed and crash mechanisms have been concluded. PMID:26847949

  2. Nonparametric Analysis of Bivariate Gap Time with Competing Risks

    PubMed Central

    Huang, Chiung-Yu; Wang, Chenguang; Wang, Mei-Cheng

    2016-01-01

    Summary This article considers nonparametric methods for studying recurrent disease and death with competing risks. We first point out that comparisons based on the well-known cumulative incidence function can be confounded by different prevalence rates of the competing events, and that comparisons of the conditional distribution of the survival time given the failure event type are more relevant for investigating the prognosis of different patterns of recurrence disease. We then propose nonparametric estimators for the conditional cumulative incidence function as well as the conditional bivariate cumulative incidence function for the bivariate gap times, that is, the time to disease recurrence and the residual lifetime after recurrence. To quantify the association between the two gap times in the competing risks setting, a modified Kendall’s tau statistic is proposed. The proposed estimators for the conditional bivariate cumulative incidence distribution and the association measure account for the induced dependent censoring for the second gap time. Uniform consistency and weak convergence of the proposed estimators are established. Hypothesis testing procedures for two-sample comparisons are discussed. Numerical simulation studies with practical sample sizes are conducted to evaluate the performance of the proposed nonparametric estimators and tests. An application to data from a pancreatic cancer study is presented to illustrate the methods developed in this article. PMID:26990686

  3. Risk Taking: A Required Competency for Merger, Acquisitions, and Partnerships.

    PubMed

    Trepanier, Sylvain; Crenshaw, Jeannette T; Yoder-Wise, Patricia S

    2016-01-01

    Today's nurse executive is likely to find himself or herself in the middle of a merger, acquisition, and/or partnership (MAP). This is the result of health care agencies vying for market share in the midst of stiff competition, as well as decreased reimbursement in a rapidly changing payment system. The phenomenon of MAPs is fueled by the focus on care coordination and population health management. To be prepared for the ongoing and increasing MAP activity, nurse executives need to develop the skill of risk taking as an essential competency for leading change. This article emphasizes the need to maintain and improve health care quality and patient safety. PMID:27584889

  4. Parametric estimation of P(X > Y) for normal distributions in the context of probabilistic environmental risk assessment

    PubMed Central

    Bekker, Andriëtte A.; van der Voet, Hilko; ter Braak, Cajo J.F.

    2015-01-01

    Estimating the risk, P(X > Y), in probabilistic environmental risk assessment of nanoparticles is a problem when confronted by potentially small risks and small sample sizes of the exposure concentration X and/or the effect concentration Y. This is illustrated in the motivating case study of aquatic risk assessment of nano-Ag. A non-parametric estimator based on data alone is not sufficient as it is limited by sample size. In this paper, we investigate the maximum gain possible when making strong parametric assumptions as opposed to making no parametric assumptions at all. We compare maximum likelihood and Bayesian estimators with the non-parametric estimator and study the influence of sample size and risk on the (interval) estimators via simulation. We found that the parametric estimators enable us to estimate and bound the risk for smaller sample sizes and small risks. Also, the Bayesian estimator outperforms the maximum likelihood estimators in terms of coverage and interval lengths and is, therefore, preferred in our motivating case study. PMID:26312175

  5. Developing points-based risk-scoring systems in the presence of competing risks.

    PubMed

    Austin, Peter C; Lee, Douglas S; D'Agostino, Ralph B; Fine, Jason P

    2016-09-30

    Predicting the occurrence of an adverse event over time is an important issue in clinical medicine. Clinical prediction models and associated points-based risk-scoring systems are popular statistical methods for summarizing the relationship between a multivariable set of patient risk factors and the risk of the occurrence of an adverse event. Points-based risk-scoring systems are popular amongst physicians as they permit a rapid assessment of patient risk without the use of computers or other electronic devices. The use of such points-based risk-scoring systems facilitates evidence-based clinical decision making. There is a growing interest in cause-specific mortality and in non-fatal outcomes. However, when considering these types of outcomes, one must account for competing risks whose occurrence precludes the occurrence of the event of interest. We describe how points-based risk-scoring systems can be developed in the presence of competing events. We illustrate the application of these methods by developing risk-scoring systems for predicting cardiovascular mortality in patients hospitalized with acute myocardial infarction. Code in the R statistical programming language is provided for the implementation of the described methods. © 2016 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd. PMID:27197622

  6. A new flexible dependence measure for semi-competing risks.

    PubMed

    Yang, Jing; Peng, Limin

    2016-09-01

    Semi-competing risks data are often encountered in chronic disease follow-up studies that record both nonterminal events (e.g., disease landmark events) and terminal events (e.g., death). Studying the relationship between the nonterminal event and the terminal event can provide insightful information on disease progression. In this article, we propose a new sensible dependence measure tailored to addressing such an interest. We develop a nonparametric estimator, which is general enough to handle both independent right censoring and left truncation. Our strategy of connecting the new dependence measure with quantile regression enables a natural extension to adjust for covariates with minor additional assumptions imposed. We establish the asymptotic properties of the proposed estimators and develop inferences accordingly. Simulation studies suggest good finite-sample performance of the proposed methods. Our proposals are illustrated via an application to Denmark diabetes registry data. PMID:26916804

  7. Competing risk analysis using R: an easy guide for clinicians.

    PubMed

    Scrucca, L; Santucci, A; Aversa, F

    2007-08-01

    In the last decade with widespread use of quantitative analyses in medical research, close co-operation between statisticians and physicians has become essential from the experimental design through all phases of complex statistical analysis. On the other hand, easy-to-use statistical packages allow clinicians to perform basic statistical analyses themselves. Since the software they most commonly use does not perform in depth competing risk analysis, we recommend an add-on package for the R statistical software. We provide all the instructions for downloading it from internet and illustrate how to use it for analysis of a sample dataset of patients who underwent haematopoietic stem cell transplantation for acute leukaemia. PMID:17563735

  8. A Method for Evaluating Competency in Assessment and Management of Suicide Risk

    ERIC Educational Resources Information Center

    Hung, Erick K.; Binder, Renee L.; Fordwood, Samantha R.; Hall, Stephen E.; Cramer, Robert J.; McNiel, Dale E.

    2012-01-01

    Objective: Although health professionals increasingly are expected to be able to assess and manage patients' risk for suicide, few methods are available to evaluate this competency. This report describes development of a competency-assessment instrument for suicide risk-assessment (CAI-S), and evaluates its use in an objective structured clinical…

  9. Taking apart the art: the risk of anatomizing clinical competence.

    PubMed

    Huddle, Thomas S; Heudebert, Gustavo R

    2007-06-01

    The Accreditation Council for Graduate Medical Education (ACGME) is encouraging medical residency programs to objectively assess their trainees for possession of six general clinical competencies by the completion of residency training. This is the thrust of the ACGME Outcome Project, now in its seventh year. As residency programs seek to integrate the general competencies into clinical training, educators have begun to suggest that objective assessment of clinical competence may be able to guide decisions about length of training and timing of subspecialization. The authors contend that higher-level competence is not amenable to assessment by the objective comparison of resident performance with learning objectives, even if such objectives are derived from general competencies. Present-day attempts at such assessment echo the uses to which medical schools hoped to put curricular learning objectives in the 1970s. Objective assessment may capture knowledge and skills that amount to the "building blocks" of competence, but it cannot elucidate or scrutinize higher-level clinical competence. Higher-level competence involves sensitivity to clinical context and can be validly appraised only in such a context by fully competent clinical appraisers. Such assessment is necessarily subjective, but it need not be unreproducible if raters are trained and if sampling of trainee performance is sufficiently extensive. If the ACGME approach to clinical competency is indeed brought to bear on decisions about training length and subspecialization timing, the present apprenticeship model for clinical training in the United States, a model both remarkably successful and directly descendant from Osler's innovations, will be under threat. PMID:17525535

  10. Modelling competing risks in nephrology research: an example in peritoneal dialysis

    PubMed Central

    2013-01-01

    Background Modelling competing risks is an essential issue in Nephrology Research. In peritoneal dialysis studies, sometimes inappropriate methods (i.e. Kaplan-Meier method) have been used to estimate probabilities for an event of interest in the presence of competing risks. In this situation a competing risk analysis should be preferable. The objectives of this study are to describe the bias resulting from the application of standard survival analysis to estimate peritonitis-free patient survival and to provide alternative statistical approaches taking competing risks into account. Methods The sample comprises patients included in a university hospital peritoneal dialysis program between October 1985 and June 2011 (n = 449). Cumulative incidence function and competing risk regression models based on cause-specific and subdistribution hazards were discussed. Results The probability of occurrence of the first peritonitis is wrongly overestimated using Kaplan-Meier method. The cause-specific hazard model showed that factors associated with shorter time to first peritonitis were age (≥55 years) and previous treatment (haemodialysis). Taking competing risks into account in the subdistribution hazard model, age remained significant while gender (female) but not previous treatment was identified as a factor associated with a higher probability of first peritonitis event. Conclusions In the presence of competing risks outcomes, Kaplan-Meier estimates are biased as they overestimated the probability of the occurrence of an event of interest. Methods which take competing risks into account provide unbiased estimates of cumulative incidence for each specific outcome experienced by patients. Multivariable regression models such as those based on cause-specific hazard and on subdistribution hazard should be used in this competing risk setting. PMID:23705871

  11. Media influence on risk competence in self-medication and self-treatment

    PubMed Central

    Schweim, Harald; Ullmann, Marcela

    2015-01-01

    Media play an important role in the reception of health risks; thus, media competence is important for enhancing the risk competence of patients and consumers. In addition to life-long health education, risk competence particularly requires careful handling of health information because, at present, the key problem is not the lack of sufficient information on health topics but the quality of such information. Patients and consumers of health procedures and health products also require information which relates to their daily life and matches their life style. PMID:26195923

  12. Media influence on risk competence in self-medication and self-treatment.

    PubMed

    Schweim, Harald; Ullmann, Marcela

    2015-01-01

    Media play an important role in the reception of health risks; thus, media competence is important for enhancing the risk competence of patients and consumers. In addition to life-long health education, risk competence particularly requires careful handling of health information because, at present, the key problem is not the lack of sufficient information on health topics but the quality of such information. Patients and consumers of health procedures and health products also require information which relates to their daily life and matches their life style. PMID:26195923

  13. Predicting Emotional and Social Competence during Early Childhood from Toddler Risk and Maternal Behavior

    PubMed Central

    Blandon, Alysia Y.; Calkins, Susan D.; Keane, Susan P.

    2010-01-01

    The longitudinal associations between maternal parenting behavior and toddler risk with children’s emotional and social competence were examined during the transition to kindergarten, in a sample of 253 children. Toddler risk was characterized by early externalizing behavior and poor emotion regulation skills. Given that we were interested in the multiple pathways that may result in emotional and social competence, we examined the interactions among maternal parenting behavior and toddler risk. There were some significant interactions; although the pattern of results was not consistent across all competence outcomes. Maternal parenting behavior was not directly associated with children’s emotional and social competence. In some instances, maternal control has differential implications for children’s emotional and social competence dependent upon the child’s level of early risk and maternal positive parenting. Specifically, maternal control tended to be more detrimental for children’s emotional competence during the transition to kindergarten, when children exhibit higher levels of risk. Overall, it appears that there are multiple developmental pathways, depending on child and maternal characteristics that lead to early emotional and social competence. PMID:20102651

  14. Survival Analysis in the Presence of Competing Risks: The Example of Waitlisted Kidney Transplant Candidates.

    PubMed

    Sapir-Pichhadze, R; Pintilie, M; Tinckam, K J; Laupacis, A; Logan, A G; Beyene, J; Kim, S J

    2016-07-01

    Competing events (or risks) preclude the observation of an event of interest or alter the probability of the event's occurrence and are commonly encountered in transplant outcomes research. Transplantation, for example, is a competing event for death on the waiting list because receiving a transplant may significantly decrease the risk of long-term mortality. In a typical analysis of time-to-event data, competing events may be censored or incorporated into composite end points; however, the presence of competing events violates the assumption of "independent censoring," which is the basis of standard survival analysis techniques. The use of composite end points disregards the possibility that competing events may be related to the exposure in a way that is different from the other components of the composite. Using data from the Scientific Registry of Transplant Recipients, this paper reviews the principles of competing risks analysis; outlines approaches for analyzing data with competing events (cause-specific and subdistribution hazards models); compares the estimates obtained from standard survival analysis, which handle competing events as censoring events; discusses the appropriate settings in which each of the two approaches could be used; and contrasts their interpretation. PMID:26751409

  15. Suicide Risk Assessment Training for Psychology Doctoral Programs: Core Competencies and a Framework for Training

    PubMed Central

    Cramer, Robert J.; Johnson, Shara M.; McLaughlin, Jennifer; Rausch, Emilie M.; Conroy, Mary Alice

    2014-01-01

    Clinical and counseling psychology programs currently lack adequate evidence-based competency goals and training in suicide risk assessment. To begin to address this problem, this article proposes core competencies and an integrated training framework that can form the basis for training and research in this area. First, we evaluate the extent to which current training is effective in preparing trainees for suicide risk assessment. Within this discussion, sample and methodological issues are reviewed. Second, as an extension of these methodological training issues, we integrate empirically- and expert-derived suicide risk assessment competencies from several sources with the goal of streamlining core competencies for training purposes. Finally, a framework for suicide risk assessment training is outlined. The approach employs Objective Structured Clinical Examination (OSCE) methodology, an approach commonly utilized in medical competency training. The training modality also proposes the Suicide Competency Assessment Form (SCAF), a training tool evaluating self- and observer-ratings of trainee core competencies. The training framework and SCAF are ripe for empirical evaluation and potential training implementation. PMID:24672588

  16. [Non-Parametric Analysis of Radiation Risks of Mortality among Chernobyl Clean-Up Workers].

    PubMed

    Gorsky, A I; Maksioutov, M A; Tumanov, K A; Shchukina, N V; Chekin, S Yu; Ivanov, V K

    2016-01-01

    Analysis of the relationship between dose and mortality from cancer and circulation diseases in the cohort of Chernobyl clean-up workers based on the data from the National Radiation and Epidemiological Registry was performed. Medical and dosimetry information on the clean-up workers, males, who got radiation doses from April 26, 1986 to April 26, 1987, which was accumulated from 1992 to 2012, was used for the analysis. The total size of the cohort was 42929 people, 12731 deaths were registered in the cohort, among them 1893 deaths from solid cancers and 5230 deaths were from circulation diseases. An average age of the workers was 39 years in 1992 and the mean dose was 164 mGy. The dose-effect relationship was estimated with the use of non-parametric analysis of survival with regard to concurrence of risks of mortality. The risks were estimated in 6 dose groups of similar size (1-70, 70-130, 130-190, 190-210, 210-230 and.230-1000 mGy). The group "1-70 mGy" was used as control. Estimated dose-effect relationship related to cancers and circulation diseases is described approximately with a linear model, coefficient of determination (the proportion of variability explained by the linear model) for cancers was 23-25% and for circulation diseases - 2-13%. The slope coefficient of the dose-effect relationship normalized to 1 Gy for the ratio of risks for cancers in the linear model was 0.47 (95% CI: -0.77, 1.71), and for circulation diseases it was 0.22 (95% CI: -0.58, 1.02). Risks coefficient (slope coefficient of excess mortality at a dose of 1 Gy) for solid cancers was 1.94 (95% CI: - 3.10, 7.00) x 10(-2) and for circulation diseases it was 0.67 (95% CI: -9.61, 11.00) x 10(-2). 137 deaths from radiation-induced cancers and 47 deaths from circulation diseases were registered during a follow up period. PMID:27534064

  17. Core Competencies and the Prevention of High-Risk Sexual Behavior

    ERIC Educational Resources Information Center

    Charles, Vignetta Eugenia; Blum, Robert Wm.

    2008-01-01

    Adolescent sexual risk-taking behavior has numerous individual, family, community, and societal consequences. In an effort to contribute to the research and propose new directions, this chapter applies the core competencies framework to the prevention of high-risk sexual behavior. It describes the magnitude of the problem, summarizes explanatory…

  18. Introduction to the Analysis of Survival Data in the Presence of Competing Risks.

    PubMed

    Austin, Peter C; Lee, Douglas S; Fine, Jason P

    2016-02-01

    Competing risks occur frequently in the analysis of survival data. A competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. In a study examining time to death attributable to cardiovascular causes, death attributable to noncardiovascular causes is a competing risk. When estimating the crude incidence of outcomes, analysts should use the cumulative incidence function, rather than the complement of the Kaplan-Meier survival function. The use of the Kaplan-Meier survival function results in estimates of incidence that are biased upward, regardless of whether the competing events are independent of one another. When fitting regression models in the presence of competing risks, researchers can choose from 2 different families of models: modeling the effect of covariates on the cause-specific hazard of the outcome or modeling the effect of covariates on the cumulative incidence function. The former allows one to estimate the effect of the covariates on the rate of occurrence of the outcome in those subjects who are currently event free. The latter allows one to estimate the effect of covariates on the absolute risk of the outcome over time. The former family of models may be better suited for addressing etiologic questions, whereas the latter model may be better suited for estimating a patient's clinical prognosis. We illustrate the application of these methods by examining cause-specific mortality in patients hospitalized with heart failure. Statistical software code in both R and SAS is provided. PMID:26858290

  19. Students "At-Risk" Policy: Competing Social and Economic Discourses

    ERIC Educational Resources Information Center

    Mosen-Lowe, Linda Audrey Joy; Vidovich, Lesley; Chapman, Anne

    2009-01-01

    Within a context of global reform agendas that promote economic ideologies in education the discourses surrounding "school failure" have shifted from "individual risk" to "a nation at-risk". Enhancing the quality of schooling through improving educational outcomes and standards for all, and thereby reducing "school failure," is simultaneously…

  20. Self-criticism of physicians, patient participation and risk competence

    PubMed Central

    Wolffsohn, Michael

    2015-01-01

    Self-criticism of physicians and patient participation are the pillars of modern medical ethics and medical programmes. Patients expect risk minimisation from physicians, mostly without realising how much they could actively do themselves in this respect. But what about the willingness of German people to take risks, how high is it really at present? Direct empirical data are not available, but results from general empirical research show that people’s willingness to take risks is probably rather low. Post-heroic societies of welfare states are less likely to take risks than supposedly heroic ones. Therefore, the question whether it is responsible for medical experts to transfer even more responsibility to non-medical laypeople becomes increasingly important in a social context. PMID:26195919

  1. Are women as likely to take risks and compete? Behavioural findings from central Vietnam.

    PubMed

    Fletschner, Diana; Anderson, C Leigh; Cullen, Alison

    2010-01-01

    Using controlled experiments to compare the risk attitude and willingness to compete of husbands and wives in 500 couples in rural Vietnam, we find that women are more risk averse than men and that, compared to men, women are less likely to choose to compete, irrespective of how likely they are to succeed. Relevant to development programmes concerned with lifting women out of poverty, our findings suggest that women may be more reluctant to adopt new technologies, take out loans, or engage in economic activities that offer higher expected returns, in order to avoid setups that require them to be more competitive or that have less predictable outcomes. PMID:21125722

  2. Contextual risk and parenting as predictors of effortful control and social competence in preschool children

    PubMed Central

    Lengua, Liliana J.; Honorado, Elizabeth; Bush, Nicole R.

    2011-01-01

    Using a short-term longitudinal design (6 months), this study examined cumulative contextual risk as a predictor of effortful control (EC) and social competence in a community sample of children (N = 80, ages 33–40 months at time 1). Maternal parenting was examined as a mediator of contextual risk. EC was assessed using laboratory tasks, and parenting was assessed using observational ratings. Time 1 contextual risk was negatively related to time 2 EC after controlling for time 1 EC. Mothers’ limit setting and scaffolding predicted higher time 2 EC and accounted for the effect of contextual risk. Time 1 EC, contextual risk, and parenting predicted time 2 social competence, and contextual risk had an indirect effect on social competence through parenting. Results suggest that contextual risk predicts smaller relative increases in EC and that parenting accounts for this effect. Knowledge of the factors that divert or promote effortful control can provide targets for intervention to enhance effortful control abilities and better adjustment. PMID:21687825

  3. Contextual risk and parenting as predictors of effortful control and social competence in preschool children.

    PubMed

    Lengua, Liliana J; Honorado, Elizabeth; Bush, Nicole R

    2007-01-01

    Using a short-term longitudinal design (6 months), this study examined cumulative contextual risk as a predictor of effortful control (EC) and social competence in a community sample of children (N = 80, ages 33-40 months at time 1). Maternal parenting was examined as a mediator of contextual risk. EC was assessed using laboratory tasks, and parenting was assessed using observational ratings. Time 1 contextual risk was negatively related to time 2 EC after controlling for time 1 EC. Mothers' limit setting and scaffolding predicted higher time 2 EC and accounted for the effect of contextual risk. Time 1 EC, contextual risk, and parenting predicted time 2 social competence, and contextual risk had an indirect effect on social competence through parenting. Results suggest that contextual risk predicts smaller relative increases in EC and that parenting accounts for this effect. Knowledge of the factors that divert or promote effortful control can provide targets for intervention to enhance effortful control abilities and better adjustment. PMID:21687825

  4. Rapid Risk-Based Evaluation of Competing Conceptual Designs

    SciTech Connect

    Bott, T.F.; Butner, J.M.

    1999-08-22

    In this paper, the authors have shown how a qualitative analysis can provide good input to a risk reduction design problem. Traditionally qualitative analyses such as the FMEA can be supplemented by qualitative fault trees and event trees to produce logic models of the accident sequences for the different design options. These models can be compared using rule-based manipulations of qualitative branch point probabilities. A qualitative evaluation of other considerations such as collateral safety effects, operational impacts and worker-safety impacts can provide a more complete picture of the trade-off between options. The authors believe that their risk-reduction analysis approach that combines logic models with qualitative and possibility metrics provides an excellent tool for incorporating safety concerns rapidly and effectively into a conceptual design evaluation.

  5. Social Competence of Students with Learning Disabilities Using a Risk-Resilience Model

    ERIC Educational Resources Information Center

    Benowitz, Alison Joy

    2010-01-01

    Children with learning disabilities (LD) makeup 50.5% of all children identified for special services in the schools. Research has found that children with LD have difficulties in areas of functioning related to social competence. This study is based on a risk and resilience model to explore external protective factors (friendships and social…

  6. Analysis of Intravenous Glucose Tolerance Test Data Using Parametric and Nonparametric Modeling: Application to a Population at Risk for Diabetes

    PubMed Central

    Marmarelis, Vasilis Z.; Shin, Dae C.; Zhang, Yaping; Kautzky-Willer, Alexandra; Pacini, Giovanni; D’Argenio, David Z.

    2013-01-01

    Background: Modeling studies of the insulin–glucose relationship have mainly utilized parametric models, most notably the minimal model (MM) of glucose disappearance. This article presents results from the comparative analysis of the parametric MM and a nonparametric Laguerre based Volterra Model (LVM) applied to the analysis of insulin modified (IM) intravenous glucose tolerance test (IVGTT) data from a clinical study of gestational diabetes mellitus (GDM). Methods: An IM IVGTT study was performed 8 to 10 weeks postpartum in 125 women who were diagnosed with GDM during their pregnancy [population at risk of developing diabetes (PRD)] and in 39 control women with normal pregnancies (control subjects). The measured plasma glucose and insulin from the IM IVGTT in each group were analyzed via a population analysis approach to estimate the insulin sensitivity parameter of the parametric MM. In the nonparametric LVM analysis, the glucose and insulin data were used to calculate the first-order kernel, from which a diagnostic scalar index representing the integrated effect of insulin on glucose was derived. Results: Both the parametric MM and nonparametric LVM describe the glucose concentration data in each group with good fidelity, with an improved measured versus predicted r2 value for the LVM of 0.99 versus 0.97 for the MM analysis in the PRD. However, application of the respective diagnostic indices of the two methods does result in a different classification of 20% of the individuals in the PRD. Conclusions: It was found that the data based nonparametric LVM revealed additional insights about the manner in which infused insulin affects blood glucose concentration. PMID:23911176

  7. Evidence-based health information and risk competence

    PubMed Central

    Mühlhauser, Ingrid; Albrecht, Martina; Steckelberg, Anke

    2015-01-01

    Consumers and patients want to be included in decisions regarding their own health and have an ethically justified claim on informed decisions. Therefore, sound information is required, but health information is often misleading and based on different interests. The risks of disease and the benefits of medical interventions tend to be overestimated, whereas harm is often underestimated. Evidence-based health information has to fulfil certain criteria, for instance, it should be evidence-based, independent, complete, true as well as understandable. The aim of a medical intervention has to be explained. The different therapeutic options including the option not to intervene have to be delineated. The probabilities for success, lack of success and unwanted side effects have to be communicated in a numerical and understandable manner. Patients have the right to reject medical interventions without any sanctions. PMID:26195924

  8. A Novel Risk Score to the Prediction of 10-year Risk for Coronary Artery Disease Among the Elderly in Beijing Based on Competing Risk Model

    PubMed Central

    Liu, Long; Tang, Zhe; Li, Xia; Luo, Yanxia; Guo, Jin; Li, Haibin; Liu, Xiangtong; Tao, Lixin; Yan, Aoshuang; Guo, Xiuhua

    2016-01-01

    Abstract The study aimed to construct a risk prediction model for coronary artery disease (CAD) based on competing risk model among the elderly in Beijing and develop a user-friendly CAD risk score tool. We used competing risk model to evaluate the risk of developing a first CAD event. On the basis of the risk factors that were included in the competing risk model, we constructed the CAD risk prediction model with Cox proportional hazard model. Time-dependent receiver operating characteristic (ROC) curve and time-dependent area under the ROC curve (AUC) were used to evaluate the discrimination ability of the both methods. Calibration plots were applied to assess the calibration ability and adjusted for the competing risk of non-CAD death. Net reclassification index (NRI) and integrated discrimination improvement (IDI) were applied to quantify the improvement contributed by the new risk factors. Internal validation of predictive accuracy was performed using 1000 times of bootstrap re-sampling. Of the 1775 participants without CAD at baseline, 473 incident cases of CAD were documented for a 20-year follow-up. Time-dependent AUCs for men and women at t = 10 years were 0.841 [95% confidence interval (95% CI): 0.806–0.877], 0.804 (95% CI: 0.768–0.839) in Fine and Gray model, 0.784 (95% CI: 0.738–0.830), 0.733 (95% CI: 0.692–0.775) in Cox proportional hazard model. The competing risk model was significantly superior to Cox proportional hazard model on discrimination and calibration. The cut-off values of the risk score that marked the difference between low-risk and high-risk patients were 34 points for men and 30 points for women, which have good sensitivity and specificity. A sex-specific multivariable risk factor algorithm-based competing risk model has been developed on the basis of an elderly Chinese cohort, which could be applied to predict an individual's risk and provide a useful guide to identify the groups at a high risk for CAD among the Chinese

  9. Intelligence quotient discrepancy indicates levels of motor competence in preschool children at risk for developmental delays

    PubMed Central

    Yu, Tzu-Ying; Chen, Kuan-Lin; Chou, Willy; Yang, Shu-Han; Kung, Sheng-Chun; Lee, Ya-Chen; Tung, Li-Chen

    2016-01-01

    Purpose This study aimed to establish 1) whether a group difference exists in the motor competence of preschool children at risk for developmental delays with intelligence quotient discrepancy (IQD; refers to difference between verbal intelligence quotient [VIQ] and performance intelligence quotient [PIQ]) and 2) whether an association exists between IQD and motor competence. Methods Children’s motor competence and IQD were determined with the motor subtests of the Comprehensive Developmental Inventory for Infants and Toddlers and Wechsler Preschool and Primary Scale of Intelligence™ – Fourth Edition. A total of 291 children were included in three groups: NON-IQD (n=213; IQD within 1 standard deviation [SD]), VIQ>PIQ (n=39; VIQ>PIQ greater than 1 SD), and PIQ>VIQ (n=39; PIQ>VIQ greater than 1 SD). Results The results of one-way analysis of variance indicated significant differences among the subgroups for the “Gross and fine motor” subdomains of the Comprehensive Developmental Inventory for Infants and Toddlers, especially on the subtests of “body-movement coordination” (F=3.87, P<0.05) and “visual-motor coordination” (F=6.90, P<0.05). Motor competence was significantly worse in the VIQ>PIQ group than in the NON and PIQ>VIQ groups. Significant negative correlations between IQD and most of the motor subtests (r=0.31–0.46, P<0.01) were found only in the VIQ>PIQ group. Conclusion This study demonstrates that 1) IQD indicates the level of motor competence in preschoolers at risk for developmental delays and 2) IQD is negatively associated with motor competence in preschoolers with significant VIQ>PIQ discrepancy. The first finding was that preschoolers with VIQ>PIQ discrepancy greater than 1 SD performed significantly worse on motor competence than did preschoolers without significant IQD and preschoolers with PIQ>VIQ discrepancy greater than 1 SD. However, preschoolers with significant PIQ>VIQ discrepancy performed better on motor competence than

  10. [Assessment of risk of burden in construction: improvement interventions and contribution of the competent physician].

    PubMed

    Martinelli, R; Tarquini, M

    2012-01-01

    Three construction companies in three years have changed the operating modes, making use of innovative carpentry, with little amount of equipment, improved usability of the site, reduced cleaning time, less manual handling and reduced risk of accidents. The Competent Doctor has participated in the review of the risk assessment of manual handling: data has been acquired on musculoskeletal disorders to compare, in terms of this innovation, the average trend and changes, with encouraging results in terms of incidence of musculoskeletal disorders, absenteeism due to illness by these causes, new cases of lumbar diseases. It remains difficult in building to assess manual handling risk, but the collaboration between the Employer, Prevention and Protection Service and Competent Doctor, thanks to the greater attention that the design subject to these issues, suggests improvements and further steps to extend to all phases of operation of building. PMID:23405597

  11. Partial logistic artificial neural network for competing risks regularized with automatic relevance determination.

    PubMed

    Lisboa, Paulo J G; Etchells, Terence A; Jarman, Ian H; Arsene, Corneliu T C; Aung, M S Hane; Eleuteri, Antonio; Taktak, Azzam F G; Ambrogi, Federico; Boracchi, Patrizia; Biganzoli, Elia

    2009-09-01

    Time-to-event analysis is important in a wide range of applications from clinical prognosis to risk modeling for credit scoring and insurance. In risk modeling, it is sometimes required to make a simultaneous assessment of the hazard arising from two or more mutually exclusive factors. This paper applies to an existing neural network model for competing risks (PLANNCR), a Bayesian regularization with the standard approximation of the evidence to implement automatic relevance determination (PLANNCR-ARD). The theoretical framework for the model is described and its application is illustrated with reference to local and distal recurrence of breast cancer, using the data set of Veronesi (1995). PMID:19628458

  12. Covariate adjustment of cumulative incidence functions for competing risks data using inverse probability of treatment weighting.

    PubMed

    Neumann, Anke; Billionnet, Cécile

    2016-06-01

    In observational studies without random assignment of the treatment, the unadjusted comparison between treatment groups may be misleading due to confounding. One method to adjust for measured confounders is inverse probability of treatment weighting. This method can also be used in the analysis of time to event data with competing risks. Competing risks arise if for some individuals the event of interest is precluded by a different type of event occurring before, or if only the earliest of several times to event, corresponding to different event types, is observed or is of interest. In the presence of competing risks, time to event data are often characterized by cumulative incidence functions, one for each event type of interest. We describe the use of inverse probability of treatment weighting to create adjusted cumulative incidence functions. This method is equivalent to direct standardization when the weight model is saturated. No assumptions about the form of the cumulative incidence functions are required. The method allows studying associations between treatment and the different types of event under study, while focusing on the earliest event only. We present a SAS macro implementing this method and we provide a worked example. PMID:27084321

  13. The clinical course of cirrhosis: The importance of multistate models and competing risks analysis.

    PubMed

    Jepsen, Peter; Vilstrup, Hendrik; Andersen, Per Kragh

    2015-07-01

    Multistate models are models of disease progression that, for a patient group, define multiple outcome events, each of which may affect the time to develop another outcome event. Multistate models are highly relevant for studies of patients with cirrhosis; both the classical perception of cirrhosis as either compensated or decompensated and the recent, more complex models of cirrhosis progression are multistate models. Therefore, researchers who conduct clinical studies of patients with cirrhosis must realize that most of their research questions assume a multistate disease model. Failure to do so can result in severely biased results and bad clinical decisions. The analyses that can be used to study disease progression in a multistate disease model may be called competing risks analysis, named after the competing risks disease model, which is the simplest multistate disease model. In this review article, we introduce multistate disease models and competing risks analysis and explain why the standard armamentarium of Kaplan-Meier survival estimates and Cox regression sometimes gives bad answers to good questions. We also use real data to answer typical research questions about the course of cirrhosis and illustrate biases resulting from inadequate methods. Finally, we suggest statistical software packages that are helpful and accessible to the clinician-researcher. PMID:25376655

  14. Variable selection in subdistribution hazard frailty models with competing risks data

    PubMed Central

    Do Ha, Il; Lee, Minjung; Oh, Seungyoung; Jeong, Jong-Hyeon; Sylvester, Richard; Lee, Youngjo

    2014-01-01

    The proportional subdistribution hazards model (i.e. Fine-Gray model) has been widely used for analyzing univariate competing risks data. Recently, this model has been extended to clustered competing risks data via frailty. To the best of our knowledge, however, there has been no literature on variable selection method for such competing risks frailty models. In this paper, we propose a simple but unified procedure via a penalized h-likelihood (HL) for variable selection of fixed effects in a general class of subdistribution hazard frailty models, in which random effects may be shared or correlated. We consider three penalty functions (LASSO, SCAD and HL) in our variable selection procedure. We show that the proposed method can be easily implemented using a slight modification to existing h-likelihood estimation approaches. Numerical studies demonstrate that the proposed procedure using the HL penalty performs well, providing a higher probability of choosing the true model than LASSO and SCAD methods without losing prediction accuracy. The usefulness of the new method is illustrated using two actual data sets from multi-center clinical trials. PMID:25042872

  15. A Competence-Based Science Learning Framework Illustrated through the Study of Natural Hazards and Disaster Risk Reduction

    ERIC Educational Resources Information Center

    Oyao, Sheila G.; Holbrook, Jack; Rannikmäe, Miia; Pagunsan, Marmon M.

    2015-01-01

    This article proposes a competence-based learning framework for science teaching, applied to the study of "big ideas", in this case to the study of natural hazards and disaster risk reduction (NH&DRR). The framework focuses on new visions of competence, placing emphasis on nurturing connectedness and behavioral actions toward…

  16. From Reading Readiness to Reading Competence: The Role of Self-Regulation in At-Risk Children

    ERIC Educational Resources Information Center

    Smith, Leann E.; Borkowski, John G.; Whitman, Thomas L.

    2008-01-01

    This study investigated how self-regulation contributes to the development of reading competence in an at-risk sample of 157 children born to adolescent mothers. It was hypothesized that reading readiness at age 5 would shape self-regulation at age 10, which in turn would influence reading competence at age 14. Based on structural equation…

  17. The Learning and Competency Development of Master Teachers in Alternative High Schools for At-Risk Youth: A Case Study

    ERIC Educational Resources Information Center

    Williams, Nida W.

    2012-01-01

    This qualitative case study was designed to explore how master teachers in transfer high schools learn the competencies they perceive are required to engage at-risk students so that they persist and graduate. The study is based on the following assumptions: (1) The requisite teacher competencies can be defined and identified and, in fact,…

  18. Conduct problems and level of social competence in Head Start children: prevalence, pervasiveness, and associated risk factors.

    PubMed

    Webster-Stratton, C; Hammond, M

    1998-06-01

    The purpose of the current project was to determine the prevalence of conduct problems, low social competence, and associated risk factors in a sample of 4-year-old low-income children (N = 426) from 64 Head Start classrooms in the Seattle area. Conduct problems and social competence were assessed based on a combination of teacher reports, parent reports, and independent observations of children interacting with peers in the classroom and with parents at home. We examined the relative contribution of a variety of risk factors, including maternal history and socioeconomic background, current levels of stress and social support, mothers' emotional state, and parenting competence in relation to "pervasive" (i.e., at home and school) and "nonpervasive" conduct problems and low social competence. Findings indicated similar risk factors for conduct problems and for low social competence, with an ordered increase in the number of risk factors from normal to "nonpervasive" to "pervasive" groups. Harshness of parenting style (i.e., slapping, hitting, yelling) significantly distinguished between the three groups for low social competence and conduct problems. Positive affect, praise, and physical warmth from mothers were positively related to social competence but unrelated to conduct problems. PMID:11324301

  19. COMPETING RISK BIAS TO EXPLAIN THE INVERSE RELATIONSHIP BETWEEN SMOKING AND MALIGNANT MELANOMA

    PubMed Central

    Thompson, Caroline A.; Zhang, Zuo-Feng; Arah, Onyebuchi A.

    2013-01-01

    The relationship between smoking and melanoma remains unclear. Among the different results is the paradoxical finding that smoking was shown to be inversely associated with the risk of malignant melanoma in some large cohort and case-control studies, even after control for suspected confounding variables. Smoking is a known risk factor for many non-communicable diseases, including coronary heart disease, stroke, as well as other malignancies; it has been shown to be positively associated with other types of skin cancer, and there remains no clear biologic explanation for a possible protective effect on malignant melanoma. In this paper, we propose a plausible mechanism of bias from smoking-related competing risks that may explain or contribute to the inverse association between smoking and melanoma as spurious. Using directed acyclic graphs for formalization and visualization of assumptions, and Monte Carlo simulation techniques, we demonstrate how published inverse associations might be compatible with selection bias resulting from uncontrolled or unmeasured common causes of competing outcomes of smoking-related diseases and malignant melanoma. We present results from various scenarios assuming a true null as well as a true positive association between smoking and malignant melanoma. Under a true null assumption, we find inverse associations due to the biasing mechanism to be compatible with published results in the literature, especially after the addition of unmeasured confounding variables. This study could be seen as offering a cautionary note in the interpretation of published smoking-melanoma findings. PMID:23700026

  20. A Competing Risk Analysis for Hospital Length of Stay in Patients With Burns

    PubMed Central

    Taylor, Sandra L.; Sen, Soman; Greenhalgh, David G.; Lawless, MaryBeth; Curri, Terese; Palmieri, Tina L.

    2016-01-01

    IMPORTANCE Current outcome predictors for illness and injury are measured at a single time point—admission. However, patient prognosis often changes during hospitalization, limiting the usefulness of those predictions. Accurate depiction of the dynamic interaction between competing events during hospitalization may enable real-time outcome assessment. OBJECTIVE To determine how the effects of burn outcome predictors (ie, age, total body surface area burn, and inhalation injury) and the outcomes of interest (ie, mortality and length of stay) vary as a function of time throughout hospitalization. DESIGN, SETTING, AND PARTICIPANTS In this retrospective study, we used the American Burn Association’s National Burn Repository, containing outcomes and patient and injury characteristics, to identify 95 579 patients admitted with an acute burn injury to 80 tertiary American Burn Association burn centers from 2000 through 2009. We applied competing risk statistical methods to analyze patient outcomes. MAIN OUTCOMES AND MEASURES We estimated the cause-specific hazard rates for death and discharge to assess how the instantaneous risk of these events changed across time. We further evaluated the varying effects of patient age, total body surface area burn, and inhalation injury on the probability of discharge and death across time. RESULTS Maximum length of stay among patients who died was 270 days and 731 days among those discharged. Total body surface area, age, and inhalation injury had significant effects on the subdistribution hazard for discharge (P < .001); these effects varied across time (P < .002). Burn size (coefficient –0.046) determined early outcomes, while age (coefficient –0.034) determined outcomes later in the hospitalization. Inhalation injury (coefficient –0.622) played a variable role in survival and hospital length of stay. CONCLUSIONS AND RELEVANCE Real-time measurement of dynamic interrelationships among burn outcome predictors using competing

  1. Sociodemographic risk, developmental competence, and PTSD symptoms in young children exposed to interpersonal trauma in early life.

    PubMed

    Enlow, Michelle Bosquet; Blood, Emily; Egeland, Byron

    2013-12-01

    Young children are disproportionately exposed to interpersonal trauma (maltreatment, witnessing intimate partner violence [IPV]) and appear particularly susceptible to negative sequelae. Little is known about the factors influencing vulnerability to traumatic stress responses and other negative outcomes in early life. This study examined associations among interpersonal trauma exposure, sociodemographic risk, developmental competence, and posttraumatic stress disorder (PTSD) symptoms in 200 children assessed from birth to first grade via standardized observations, record reviews, and maternal and teacher interviews. More severe PTSD symptoms were predicted by greater trauma exposure (r = .43), greater sociodemographic risk (r = .22), and lower developmental competence (rs=−.31 and −.54 for preschool and school-age developmental competence, respectively). Developmental competence partially mediated the association between trauma exposure and symptoms. Trauma exposure fully mediated the association between sociodemographic risk and symptoms. Neither sociodemographic risk nor developmental competence moderated trauma exposure effects on symptoms. The findings suggest that (a)exposure to maltreatment and IPV has additive effects on posttraumatic stress risk in early life, (b) associations between sociodemographic adversity and poor mental health may be attributable to increased trauma exposure in disadvantaged populations, and (c) early exposures have a negative cascade effect on developmental competence and mental health. PMID:24490247

  2. Predictors of student outcomes on perceived knowledge and competence of genetic family history risk assessment.

    PubMed

    Collins, Cathleen A; Stiles, Anne S

    2011-01-01

    The publication of the human genome project has launched a number of discoveries set to change the landscape of healthcare. Unfortunately, nursing faculty across the United States report they are unprepared to teach students who will be practicing in the genomic era. The purpose of this study, utilizing Rogers' (2003) Diffusion of Innovation theory as a framework, was to determine the degree to which nursing school characteristics predict graduating undergraduate nursing students' perceived knowledge and competence of genetic family history risk assessment. School characteristics included school size, proximity to a large city, faculty's perceived barriers to diffusion of genomics into nursing practice, faculty innovativeness, faculty who have attended a genetics program for nursing faculty, and the integration of genomics into the curriculum. Faculty and students from 103 nursing schools across the United States participated in the study by completing online surveys. Hierarchical multiple regression was employed to determine how well the independent variables predicted student perceived knowledge and student perceived competence. No combination of the independent variables in this study predicted student knowledge or competence to the degree expected. This could be attributed to a lack of diffusion of genomics content across nursing curricula, based on Rogers' (2003) theory. Other findings included faculty continue to believe they are not competent to teach genomics, and the curriculum is too dense to include more content. However, contrary to prior research, faculty did believe genomics was valuable. The findings of this study give direction for further research into student outcomes and curriculum evaluation after 2011, when a consensus panel working to diffuse genomics into nursing curriculum and practice will have implemented their strategic plan for this diffusion. PMID:21420042

  3. A competing risk analysis of sequential complication development in Asian type 2 diabetes mellitus patients

    PubMed Central

    Cheng, Li-Jen; Chen, Jeng-Huei; Lin, Ming-Yen; Chen, Li-Chia; Lao, Chun-Huan; Luh, Hsing; Hwang, Shang-Jyh

    2015-01-01

    This retrospective cohort study investigated the progression risk of sequential complication in Asian type 2 diabetes (T2D) patients using the Taiwan Pay-for-Performance Diabetes Registry and claim data from November 2003 to February 2009. 226,310 adult T2D patients without complication were followed from diagnosis to complications, including myocardial infarction (MI), other ischemic heart disease (IHD), congestive heart failure (CHF), stroke, chronic kidney disease (CKD), retinopathy, amputation, death or to the end of study. Cumulative incidences (CIs) of first and second complications were analyzed in 30 and 4 years using the cumulative incidence competing risk method. IHD (29.8%), CKD (24.5%) and stroke (16.0%) are the most common first complications. The further development of T2D complications depends on a patient’s existing complication profiles. Patients who initially developed cardiovascular complications had a higher risk (9.2% to 24.4%) of developing IHD or CKD, respectively. All-cause mortality was the most likely consequence for patients with a prior MI (12.0%), so as stroke in patients with a prior MI (10.8%) or IHD (8.9%). Patients with CKD had higher risk of developing IHD (16.3%), stroke (8.9%) and all-cause mortality (8.7%) than end-stage renal disease (4.0%). Following an amputation, patients had a considerable risk of all-cause mortality (42.1%). PMID:26507664

  4. Varying coefficient subdistribution regression for left-truncated semi-competing risks data

    PubMed Central

    Li, Ruosha

    2014-01-01

    Semi-competing risks data frequently arise in biomedical studies when time to a disease landmark event is subject to dependent censoring by death, the observation of which however is not precluded by the occurrence of the landmark event. In observational studies, the analysis of such data can be further complicated by left truncation. In this work, we study a varying co-efficient subdistribution regression model for left-truncated semi-competing risks data. Our method appropriately accounts for the specifical truncation and censoring features of the data, and moreover has the flexibility to accommodate potentially varying covariate effects. The proposed method can be easily implemented and the resulting estimators are shown to have nice asymptotic properties. We also present inference, such as Kolmogorov-Smirnov type and Cramér Von-Mises type hypothesis testing procedures for the covariate effects. Simulation studies and an application to the Denmark diabetes registry demonstrate good finite-sample performance and practical utility of the proposed method. PMID:25125711

  5. A review of methods to estimate cause-specific mortality in presence of competing risks

    USGS Publications Warehouse

    Heisey, Dennis M.; Patterson, Brent R.

    2006-01-01

    Estimating cause-specific mortality is often of central importance for understanding the dynamics of wildlife populations. Despite such importance, methodology for estimating and analyzing cause-specific mortality has received little attention in wildlife ecology during the past 20 years. The issue of analyzing cause-specific, mutually exclusive events in time is not unique to wildlife. In fact, this general problem has received substantial attention in human biomedical applications within the context of biostatistical survival analysis. Here, we consider cause-specific mortality from a modern biostatistical perspective. This requires carefully defining what we mean by cause-specific mortality and then providing an appropriate hazard-based representation as a competing risks problem. This leads to the general solution of cause-specific mortality as the cumulative incidence function (CIF). We describe the appropriate generalization of the fully nonparametric staggered-entry Kaplan–Meier survival estimator to cause-specific mortality via the nonparametric CIF estimator (NPCIFE), which in many situations offers an attractive alternative to the Heisey–Fuller estimator. An advantage of the NPCIFE is that it lends itself readily to risk factors analysis with standard software for Cox proportional hazards model. The competing risks–based approach also clarifies issues regarding another intuitive but erroneous "cause-specific mortality" estimator based on the Kaplan–Meier survival estimator and commonly seen in the life sciences literature.

  6. Sociodemographic Risk, Developmental Competence, and PTSD Symptoms in Young Children Exposed to Interpersonal Trauma in Early Life

    PubMed Central

    Enlow, Michelle Bosquet; Blood, Emily; Egeland, Byron

    2014-01-01

    Children under age six years are disproportionately exposed to interpersonal trauma, including maltreatment and witnessing intimate partner violence (IPV), and may be particularly susceptible to negative sequelae. However, young children have generally been neglected from trauma research; thus, little is known about the factors influencing vulnerability to traumatic stress responses and other negative outcomes in early life. This study examined associations among interpersonal trauma exposure, sociodemographic risk, developmental competence, and posttraumatic stress disorder (PTSD) symptoms in 200 children assessed prospectively from birth to 1st grade via home and laboratory observations, record reviews, and maternal and teacher interviews. Greater trauma exposure and sociodemographic risk and lower developmental competence predicted more severe PTSD symptoms. Developmental competence partially mediated the association between exposures and symptoms. Trauma exposure fully mediated the association between sociodemographic risk and symptoms. Neither sociodemographic risk nor developmental competence moderated trauma exposure effects on symptoms. The findings suggest that (a) exposure to maltreatment and IPV has additive effects on posttraumatic stress risk in early life, (b) associations between sociodemographic adversity and poor mental health may be attributable to increased trauma exposure in disadvantaged populations, and (c) early exposures have a negative cascade effect on developmental competence and child mental health. PMID:24490247

  7. Competing risk analyses of longevity in Duroc sows with a special emphasis on leg conformation.

    PubMed

    Fernàndez de Sevilla, X; Fàbrega, E; Tibau, J; Casellas, J

    2009-03-01

    A competing risk approach was used to evaluate the influence of several factors on culling risk for 587 Duroc sows. Three different analyses were performed according to whether sow failure was due to death during productive life (DE) or to one of two causes for voluntary culling: low productivity (LP) and low fertility (LF). Sow survival was analyzed by the Cox model. Year at first farrowing (batch effect) significantly affected sow survival in all three analyses (P < 0.05 for DE and P < 0.001 for LP and LF) whereas farm of origin accounted for relevant variation in the LP and LF analyses. LP culling increased with backfat thickness of more than 19 mm at the end of the growth period (P < 0.05), bad teat condition (P < 0.05) and reduced piglets born alive (P < 0.001). For the LF competing risk analysis, culling increased with age at first farrowing (P < 0.1). Special emphasis was placed on the influence of leg and teat conformation on sow survivability, although they did not affect sow failure due to DE (P > 0.1). The overall leg-conformation score significantly influenced sow longevity in LP (P < 0.001) and LF competing risk analyses (P < 0.001), showing a higher hazard ratio (HR) for poorly conformed sows (1.013 and 4.366, respectively) than for well-conformed sows (0.342 and 0.246, respectively). Survival decreased with the presence of abnormal hoof growth in LP and LF analyses (HR = 3.372 and 6.002, respectively; P < 0.001) and bumps or injuries to legs (HR = 4.172 and 5.839, respectively; P < 0.01). Plantigradism reduced sow survival in the LP analysis (P < 0.05), while sickle-hooked leg (P < 0.05) impaired sow survival in the fertility-specific analysis. Estimates of heritability for longevity related to LP culling ranged from 0.008 to 0.024 depending on the estimation procedure, whereas heritability values increased to between 0.017 and 0.083 in LF analysis. These analyses highlighted substantial discrepancies in the sources of variation and genetic

  8. Competing risk: An illustration with aspiration pneumonia in head and neck cancer patients undergoing radical radiotherapy: A biostatistician's perspective.

    PubMed

    Bhattacharyya, T; Bhattacharjee, A

    2014-01-01

    Interest in survival analysis is to look and capture the information about the occurrence of events, i.e., death. In human life different types of events may happen at the same time. Sometimes, few events completely interrupt or make subtle changes on the occurrence of an event of interest. The method to capture information about the specific event of interest along with other events is known as competing risk modeling. This paper is dedicated to explore the application of competing risk model in oncology practice. It is aimed in near future that more and more survival analysis will be performed through application of competing risk modeling instead of traditional survival analysis to generate robust statistical inference. PMID:26842137

  9. Competing Risk Analysis for Evaluation of Dalteparin Versus Unfractionated Heparin for Venous Thromboembolism in Medical-Surgical Critically Ill Patients

    PubMed Central

    Li, Guowei; Cook, Deborah J.; Levine, Mitchell A.H.; Guyatt, Gordon; Crowther, Mark; Heels-Ansdell, Diane; Holbrook, Anne; Lamontagne, Francois; Walter, Stephen D.; Ferguson, Niall D.; Finfer, Simon; Arabi, Yaseen M.; Bellomo, Rinaldo; Cooper, D. Jamie; Thabane, Lehana

    2015-01-01

    Abstract Failure to recognize the presence of competing risk or to account for it may result in misleading conclusions. We aimed to perform a competing risk analysis to assess the efficacy of the low molecular weight heparin dalteparin versus unfractionated heparin (UFH) in venous thromboembolism (VTE) in medical-surgical critically ill patients, taking death as a competing risk. This was a secondary analysis of a prospective randomized study of the Prophylaxis for Thromboembolism in Critical Care Trial (PROTECT) database. A total of 3746 medical-surgical critically ill patients from 67 intensive care units (ICUs) in 6 countries receiving either subcutaneous UFH 5000 IU twice daily (n = 1873) or dalteparin 5000 IU once daily plus once-daily placebo (n = 1873) were included for analysis. A total of 205 incident proximal leg deep vein thromboses (PLDVT) were reported during follow-up, among which 96 were in the dalteparin group and 109 were in the UFH group. No significant treatment effect of dalteparin on PLDVT compared with UFH was observed in either the competing risk analysis or standard survival analysis (also known as cause-specific analysis) using multivariable models adjusted for APACHE II score, history of VTE, need for vasopressors, and end-stage renal disease: sub-hazard ratio (SHR) = 0.92, 95% confidence interval (CI): 0.70–1.21, P-value = 0.56 for the competing risk analysis; hazard ratio (HR) = 0.92, 95% CI: 0.68–1.23, P-value = 0.57 for cause-specific analysis. Dalteparin was associated with a significant reduction in risk of pulmonary embolism (PE): SHR = 0.54, 95% CI: 0.31–0.94, P-value = 0.02 for the competing risk analysis; HR = 0.51, 95% CI: 0.30–0.88, P-value = 0.01 for the cause-specific analysis. Two additional sensitivity analyses using the treatment variable as a time-dependent covariate and using as-treated and per-protocol approaches demonstrated similar findings. This competing risk analysis

  10. Competing Risk Analysis for Evaluation of Dalteparin Versus Unfractionated Heparin for Venous Thromboembolism in Medical-Surgical Critically Ill Patients.

    PubMed

    Li, Guowei; Cook, Deborah J; Levine, Mitchell A H; Guyatt, Gordon; Crowther, Mark; Heels-Ansdell, Diane; Holbrook, Anne; Lamontagne, Francois; Walter, Stephen D; Ferguson, Niall D; Finfer, Simon; Arabi, Yaseen M; Bellomo, Rinaldo; Cooper, D Jamie; Thabane, Lehana

    2015-09-01

    Failure to recognize the presence of competing risk or to account for it may result in misleading conclusions. We aimed to perform a competing risk analysis to assess the efficacy of the low molecular weight heparin dalteparin versus unfractionated heparin (UFH) in venous thromboembolism (VTE) in medical-surgical critically ill patients, taking death as a competing risk.This was a secondary analysis of a prospective randomized study of the Prophylaxis for Thromboembolism in Critical Care Trial (PROTECT) database. A total of 3746 medical-surgical critically ill patients from 67 intensive care units (ICUs) in 6 countries receiving either subcutaneous UFH 5000 IU twice daily (n = 1873) or dalteparin 5000 IU once daily plus once-daily placebo (n = 1873) were included for analysis.A total of 205 incident proximal leg deep vein thromboses (PLDVT) were reported during follow-up, among which 96 were in the dalteparin group and 109 were in the UFH group. No significant treatment effect of dalteparin on PLDVT compared with UFH was observed in either the competing risk analysis or standard survival analysis (also known as cause-specific analysis) using multivariable models adjusted for APACHE II score, history of VTE, need for vasopressors, and end-stage renal disease: sub-hazard ratio (SHR) = 0.92, 95% confidence interval (CI): 0.70-1.21, P-value = 0.56 for the competing risk analysis; hazard ratio (HR) = 0.92, 95% CI: 0.68-1.23, P-value = 0.57 for cause-specific analysis. Dalteparin was associated with a significant reduction in risk of pulmonary embolism (PE): SHR = 0.54, 95% CI: 0.31-0.94, P-value = 0.02 for the competing risk analysis; HR = 0.51, 95% CI: 0.30-0.88, P-value = 0.01 for the cause-specific analysis. Two additional sensitivity analyses using the treatment variable as a time-dependent covariate and using as-treated and per-protocol approaches demonstrated similar findings.This competing risk analysis yields no

  11. Loss to Follow-Up as a Competing Risk in an Observational Study of HIV-1 Incidence

    PubMed Central

    Graham, Susan M.; Raboud, Janet; McClelland, R. Scott; Jaoko, Walter; Ndinya-Achola, Jeckoniah; Mandaliya, Kishor; Overbaugh, Julie; Bayoumi, Ahmed M.

    2013-01-01

    Objective Conventional survival estimates may be biased if loss to follow-up (LTF) is associated with the outcome of interest. Our goal was to assess whether the association between sexual risk behavior and HIV-1 acquisition changed after accounting for LTF with competing risks regression. Methods HIV-1-seronegative women who enrolled in a Kenyan sex worker cohort from 1993–2007 were followed prospectively and tested for HIV at monthly clinic visits. Our primary predictor was self-reported sexual risk behavior in the past week, analyzed as a time-dependent covariate. Outcomes included HIV-1 acquisition and LTF. We analyzed the data using Cox proportional hazards regression and competing risks regression, in which LTF was treated as a competing event. Results A total of 1,513 women contributed 4,150 person-years (py), during which 198 (13.1%) acquired HIV-1 infection (incidence, 4.5 per 100 py) and 969 (64.0%) were LTF (incidence, 23.4 per 100 py). After adjusting for potential confounders, women reporting unprotected sex with multiple partners were less likely to be lost to follow-up (adjusted sub-hazard ratio (aSHR) 0.50, 95% confidence interval (CI) 0.32–0.76, relative to no sexual activity). The risk of HIV-1 acquisition after reporting unprotected sex with multiple partners was similar with Cox regression (adjusted hazard ratio (aHR) 2.41, 95% CI 1.36–4.27) and competing risks regression (aSHR 2.47, 95% CI 1.33–4.58). Conclusions Unprotected sex with multiple partners was associated with higher HIV-1 acquisition risk, but lower attrition. This differential attrition did not substantially bias Cox regression estimates when compared to competing risks regression results. PMID:23555041

  12. Marginal and Conditional Distribution Estimation from Double-Sampled Semi-Competing Risks Data

    PubMed Central

    Yu, Menggang; Yiannoutsos, Constantin T

    2015-01-01

    Informative dropout is a vexing problem for any biomedical study. Most existing statistical methods attempt to correct estimation bias related to this phenomenon by specifying unverifiable assumptions about the dropout mechanism. We consider a cohort study in Africa that uses an outreach program to ascertain the vital status for dropout subjects. These data can be used to identify a number of relevant distributions. However, as only a subset of dropout subjects were followed, vital status ascertainment was incomplete. We use semi-competing risk methods as our analysis framework to address this specific case where the terminal event is incompletely ascertained and consider various procedures for estimating the marginal distribution of dropout and the marginal and conditional distributions of survival. We also consider model selection and estimation efficiency in our setting. Performance of the proposed methods is demonstrated via simulations, asymptotic study, and analysis of the study data. PMID:26924877

  13. A Bayesian approach to joint analysis of longitudinal measurements and competing risks failure time data.

    PubMed

    Hu, Wenhua; Li, Gang; Li, Ning

    2009-05-15

    In this paper, we develop a Bayesian method for joint analysis of longitudinal measurements and competing risks failure time data. The model allows one to analyze the longitudinal outcome with nonignorable missing data induced by multiple types of events, to analyze survival data with dependent censoring for the key event, and to draw inferences on multiple endpoints simultaneously. Compared with the likelihood approach, the Bayesian method has several advantages. It is computationally more tractable for high-dimensional random effects. It is also convenient to draw inference. Moreover, it provides a means to incorporate prior information that may help to improve estimation accuracy. An illustration is given using a clinical trial data of scleroderma lung disease. The performance of our method is evaluated by simulation studies. PMID:19308919

  14. Bayesian Gamma Frailty Models for Survival Data with Semi-Competing Risks and Treatment Switching

    PubMed Central

    Zhang, Yuanye; Chen, Ming-Hui; Ibrahim, Joseph G.; Zeng, Donglin; Chen, Qingxia; Pan, Zhiying; Xue, Xiaodong

    2013-01-01

    Motivated from a colorectal cancer study, we propose a class of frailty semi-competing risks survival models to account for the dependence between disease progression time, survival time, and treatment switching. Properties of the proposed models are examined and an efficient Gibbs sampling algorithm using the collapsed Gibbs technique is developed. A Bayesian procedure for assessing the treatment effect is also proposed. The Deviance Information Criterion (DIC) with an appropriate deviance function and Logarithm of the Pseudomarginal Likelihood (LPML) are constructed for model comparison. A simulation study is conducted to examine the empirical performance of DIC and LPML and as well as the posterior estimates. The proposed method is further applied to analyze data from a colorectal cancer study. PMID:23543121

  15. Resilience and risk competence in schools: theory/knowledge and international application in project rebound.

    PubMed

    Brown, Joel H; Jean-Marie, Gaetane; Beck, Jerome

    2010-01-01

    Despite a 50-year interdisciplinary and longitudinal research legacy--showing that nearly 80% of young people considered most "at risk" thrive by midlife-only recently have practitioners/researchers engaged in the explicit, prospective facilitation of "resilience" in educational settings. Here, theory/knowledge distinguishing and extending risk and resilience from its risk-based social history to resilience's normative occurrence leads to the first known international and prospective application of resilience in school-based drug education, Project REBOUND [resilience-bound]. It will be implemented as a controlled pilot study, first in Germany, then expand to the United States, as well as other parts of Europe. With evaluation occurring throughout, the goal is to enhance the quality of drug decisions among young people, as well as support their overall competence-based learning and development throughout school. With limitations and underlying psychological mechanisms discussed, it is concluded Project REBOUND offers promising potential for supporting positive drug decisions as well as youth learning and development. PMID:21381462

  16. Connection between competence, usability, environment and risk of falls in elderly adults

    PubMed Central

    Leiva-Caro, José Alex; Salazar-González, Bertha Cecilia; Gallegos-Cabriales, Esther Carlota; Gómez-Meza, Marco Vinicio; Hunter, Kathleen F.

    2015-01-01

    Objective: to determine connections between competence, usability, environment and risk of falls in elderly adults. Method: correlational descriptive study, 123 elderly adults, both male and female, aged 70 years and older were included. Data was collected via the Tinetti Scale, CESD-7 Scale, Montreal Cognitive Assessment, Usability Questionnaire on Housing and Housing Enabler; and sociodemographic and health background certificate data. For data analysis, descriptive and inferential statistics were used, multivariate linear and logistic regression models were adjusted. Results: 42.0% of the elderly adults had presented with falls, with a higher prevalence in women, and in the group of 70-75 years. The physical environment of the house, gait, and usability were set as risk factors for falls. A negative relationship between usability and depressive symptoms, cognitive health, balance, gait, the social and physical environment was found, p <0.05; and a strong positive correlation between walking and balance, p <0.05. Conclusion: this study helps to better understand the phenomenon of falling, to find a connection between usability with the risk of falls, and other variables. PMID:26626006

  17. Potential for Early Fracture Risk Assessment in Patients with Metastatic Bone Disease using Parametric Response Mapping of CT Images

    PubMed Central

    Hoff, Benjamin A.; Toole, Michael; Yablon, Corrie; Ross, Brian D.; Luker, Gary D.; VanPoznak, Catherine; Galbán, Craig J.

    2016-01-01

    Pathologic vertebral compression fractures (PVCF) cause significant morbidity in patients with bone metastases from breast cancer and other malignancies. Due to limitations of existing biochemical and imaging biomarkers, clinicians currently have no reliable metrics to identify patients with impending PVCF, impeding efforts to prevent this severe complication. To establish the feasibility of a new method for defining risk of PVCF, we retrospectively analyzed serial CT scans from five breast cancer patients using parametric response mapping (PRM) to quantify dynamic bone density changes that preceded an event. Vertebrae segmented from each scan were registered to vertebrae at the earliest time point (i.e. furthest from PVCF) and voxel classification accomplished using a predetermined threshold of change in HU values, resulting in relative volumes of increased (PRMHU+), decreased (PRMHU−), or unchanged (PRMHU0) attenuation. A total of seven PVCF were compared to un-diseased vertebrae in each patient serving as controls. Receiver operator curve (ROC) analysis identified optimal image acquisition and analysis times for group stratification. Bone density changes were visualized by an increasing trend in PRMHU+ as early as one year before fracture. PRMHU− demonstrated negligible changes over the course of the study. These observations were consistent with ROC results, showing poor performance of PRMHU− in stratifying PVCF versus control. As early as 6 months prior to PVCF, PRMHU+ was significantly larger (12.9 ± 11.6%) compared to control vertebrae (2.3 ± 2.5%), with an AUC of 0.918 from a receiver operator curve analysis. Mean HU changes were also significant between PVCF (+26.8 ± 26.9%) and control (−2.2 ± 22.0%) over the same period. PRM analysis of bone density changes using standard CT imaging was sensitive for spatially resolving bone remodeling which preceded structural failure in patients with breast cancer vertebral metastases. PMID:26771006

  18. Examining the role of methamphetamine in permanency: A competing risks analysis of reunification, guardianship, and adoption.

    PubMed

    Akin, Becci A; Brook, Jody; Lloyd, Margaret H

    2015-03-01

    Parental methamphetamine use has drawn significant attention in recent years. Despite prior research that shows that parental substance abuse is a risk factor for lengthy foster care stay, little is known about the effect of specific types of substance use on permanency. This study sought to compare the impact of parental methamphetamine use to alcohol use, other drug use, and polysubstance use on the timing of 3 types of permanency: reunification, guardianship, and adoption. Using an entry cohort of 16,620 children who had entered foster care during a 5-year period, competing risks event history models were conducted for each permanency type. Findings showed that, after controlling for several case characteristics, parent illicit drug use significantly impacted the timing of the 3 types of permanency, but alcohol use did not. Methamphetamine, other drug, and polysubstance with methamphetamine use were associated with lower rates of reunification and higher rates of adoption. Guardianship was also predicted by other drug and polysubstance use without methamphetamine; however, methamphetamine use was not associated with guardianship. Notably, the methamphetamine groups comprised the youngest children and had the shortest median time to adoption. Results suggest that type of parental substance use is predictive of permanency exits and that parental illicit drug use may require tailored strategies for improving permanency outcomes. Further implications of the findings are discussed. PMID:25822603

  19. Competing Risks or Different Pathways? An Event History Analysis of the Relationship between Financial Aid and Educational Outcomes for Latinos

    ERIC Educational Resources Information Center

    Gross, Jacob P. K.; Torres, Vasti

    2010-01-01

    Using a competing risks event history model this study explores the effects of differentiated forms of financial aid on the postsecondary enrollment patterns of Latino college students in Indiana. Much of the prior research on financial aid has employed cross-sectional methods, which assume that the effects of aid do not vary across time. This…

  20. Cumulative Risk, the Mother-Child Relationship, and Social-Emotional Competence in Latino Head Start Children

    ERIC Educational Resources Information Center

    Martí, Maria; Bonillo, Albert; Jané, Maria Claustre; Fisher, Elisa M.; Duch, Helena

    2016-01-01

    Research Findings: Supportive mother-child interactions promote the development of social-emotional competence. Poverty and other associated psychosocial risk factors have a negative impact on mother-child interaction. In spite of Latino children being disproportionately represented among children living in poverty, research on mother-child…

  1. Sensation Seeking: A Potential Factor Influencing Perceived Risk and Perceived Competence in an Introductory Scuba Diving Course

    ERIC Educational Resources Information Center

    Morgan, Cass

    2009-01-01

    This study examined the relationship between the sensation-seeking personality trait to changes in perceived risk and perceived competence during an adventure experience. Participants (n = 57) were enrolled in a 14-week introductory scuba diving course offered at a university in eastern North Carolina in 2006. The data was analyzed using a…

  2. A consistent NPMLE of the joint distribution function with competing risks data under the dependent masking and right-censoring model.

    PubMed

    Li, Jiahui; Yu, Qiqing

    2016-01-01

    Dinse (Biometrics, 38:417-431, 1982) provides a special type of right-censored and masked competing risks data and proposes a non-parametric maximum likelihood estimator (NPMLE) and a pseudo MLE of the joint distribution function [Formula: see text] with such data. However, their asymptotic properties have not been studied so far. Under the extention of either the conditional masking probability (CMP) model or the random partition masking (RPM) model (Yu and Li, J Nonparametr Stat 24:753-764, 2012), we show that (1) Dinse's estimators are consistent if [Formula: see text] takes on finitely many values and each point in the support set of [Formula: see text] can be observed; (2) if the failure time is continuous, the NPMLE is not uniquely determined, and the standard approach (which puts weights only on one element in each observed set) leads to an inconsistent NPMLE; (3) in general, Dinse's estimators are not consistent even under the discrete assumption; (4) we construct a consistent NPMLE. The consistency is given under a new model called dependent masking and right-censoring model. The CMP model and the RPM model are indeed special cases of the new model. We compare our estimator to Dinse's estimators through simulation and real data. Simulation study indicates that the consistent NPMLE is a good approximation to the underlying distribution for moderate sample sizes. PMID:25160694

  3. Estimation of the standardized risk difference and ratio in a competing risks framework: application to injection drug use and progression to AIDS after initiation of antiretroviral therapy.

    PubMed

    Cole, Stephen R; Lau, Bryan; Eron, Joseph J; Brookhart, M Alan; Kitahata, Mari M; Martin, Jeffrey N; Mathews, William C; Mugavero, Michael J

    2015-02-15

    There are few published examples of absolute risk estimated from epidemiologic data subject to censoring and competing risks with adjustment for multiple confounders. We present an example estimating the effect of injection drug use on 6-year risk of acquired immunodeficiency syndrome (AIDS) after initiation of combination antiretroviral therapy between 1998 and 2012 in an 8-site US cohort study with death before AIDS as a competing risk. We estimate the risk standardized to the total study sample by combining inverse probability weights with the cumulative incidence function; estimates of precision are obtained by bootstrap. In 7,182 patients (83% male, 33% African American, median age of 38 years), we observed 6-year standardized AIDS risks of 16.75% among 1,143 injection drug users and 12.08% among 6,039 nonusers, yielding a standardized risk difference of 4.68 (95% confidence interval: 1.27, 8.08) and a standardized risk ratio of 1.39 (95% confidence interval: 1.12, 1.72). Results may be sensitive to the assumptions of exposure-version irrelevance, no measurement bias, and no unmeasured confounding. These limitations suggest that results be replicated with refined measurements of injection drug use. Nevertheless, estimating the standardized risk difference and ratio is straightforward, and injection drug use appears to increase the risk of AIDS. PMID:24966220

  4. Incidence and Risk Factors of Thromboembolism with Multiple Myeloma in the Presence of Death as a Competing Risk: An Empirical Comparison of Statistical Methodologies

    PubMed Central

    Brown, Joshua D.; Adams, Val R.

    2016-01-01

    Multiple myeloma (MM) has an inherent high risk of thromboembolic events associated with patient as well as disease- and treatment-related factors. Previous studies have assessed the association of MM-related thromboembolism using “traditional” Kaplan–Meier (KM) and/or Cox proportional hazard (PH) regression. In the presence of high incidence of death, as would be the case in cancer patients with advanced age, these statistical models will produce bias estimates. Instead, a competing risk framework should be used. This study assessed the baseline patient demographic and clinical characteristics associated with MM-related thromboembolism and compared the cumulative incidence and the measures of association obtained using each statistical approach. The cumulative incidence of thromboembolism was 9.2% using the competing risk framework and nearly 12% using the KM approach. Bias in the measures of covariate risk associations was highest for factors related to risk of death such as increased age (75% bias) and severe liver disease (50%) for the Cox PH model compared to the competing risk model. These results show that correct specification of statistical techniques can have a large impact on the results obtained. PMID:27417604

  5. Evaluating competing adverse and beneficial outcomes using a mixture model

    PubMed Central

    Lau, Bryan; Cole, Stephen R.; Moore, Richard D.; Gange, Stephen J.

    2008-01-01

    SUMMARY A competing risk framework occurs when individuals have the potential to experience only one of several mutually exclusive outcomes. Standard survival methods often overestimate the cumulative incidence of events when competing events are censored. Mixture distributions have been previously applied to the competing risk framework to obtain inferences regarding the subdistribution of an event of interest. Often the competing event is treated as a nuisance, but it may be of interest to compare adverse events against the beneficial outcome when dealing with an intervention. In this paper, methods for using a mixture model to estimate an adverse-benefit ratio curve (ratio of the cumulative incidence curves for the two competing events) and the ratio of the subhazards for the two competing events are presented. Both parametric and semi-parametric approaches are described with some remarks for extending the model to include uncertainty in the event type that occurred, left-truncation in order to allow for time-dependent analyses, and uncertainty in the timing of the event resulting in interval censoring. The methods are illustrated with data from a HIV clinical cohort examining whether individuals initiating effective antiretroviral therapy have a greater risk of antiretroviral discontinuation or switching compared to HIV RNA suppression. PMID:18416435

  6. Mortality and socio-economic differences in Denmark: a competing risks proportional hazard model.

    PubMed

    Munch, Jakob Roland; Svarer, Michael

    2005-03-01

    This paper explores how mortality is related to such socio-economic factors as education, occupation, skill level and income for the years 1992-1997 using an extensive sample of the Danish population. We employ a competing risks proportional hazard model to allow for different causes of death. This method is important as some factors have unequal (and sometimes opposite) influence on the cause-specific mortality rates. We find that the often-found inverse correlation between socio-economic status and mortality is to a large degree absent among Danish women who die of cancer. In addition, for men the negative correlation between socio-economic status and mortality prevails for some diseases, but for women we find that factors such as being married, income, wealth and education are not significantly associated with higher life expectancy. Marriage increases the likelihood of dying from cancer for women, early retirement prolongs survival for men, and homeownership increases life expectancy in general. PMID:15722260

  7. Quantile Regression Adjusting for Dependent Censoring from Semi-Competing Risks

    PubMed Central

    Li, Ruosha; Peng, Limin

    2014-01-01

    Summary In this work, we study quantile regression when the response is an event time subject to potentially dependent censoring. We consider the semi-competing risks setting, where time to censoring remains observable after the occurrence of the event of interest. While such a scenario frequently arises in biomedical studies, most of current quantile regression methods for censored data are not applicable because they generally require the censoring time and the event time be independent. By imposing rather mild assumptions on the association structure between the time-to-event response and the censoring time variable, we propose quantile regression procedures, which allow us to garner a comprehensive view of the covariate effects on the event time outcome as well as to examine the informativeness of censoring. An efficient and stable algorithm is provided for implementing the new method. We establish the asymptotic properties of the resulting estimators including uniform consistency and weak convergence. The theoretical development may serve as a useful template for addressing estimating settings that involve stochastic integrals. Extensive simulation studies suggest that the proposed method performs well with moderate sample sizes. We illustrate the practical utility of our proposals through an application to a bone marrow transplant trial. PMID:25574152

  8. A tool for the culturally competent assessment of suicide: the Cultural Assessment of Risk for Suicide (CARS) measure.

    PubMed

    Chu, Joyce; Floyd, Rebecca; Diep, Hy; Pardo, Seth; Goldblum, Peter; Bongar, Bruce

    2013-06-01

    Despite important differences in suicide presentation and risk among ethnic and sexual minority groups, cultural variations have typically been left out of systematic risk assessment paradigms. A new self-report instrument for the culturally competent assessment of suicide, the Cultural Assessment of Risk for Suicide (CARS) measure, was administered to a diverse sample of 950 adults from the general population. Exploratory factor analysis yielded a 39-item, 8-factor structure subsumed under and consistent with the Cultural Theory and Model of Suicide (Chu, Goldblum, Floyd, & Bongar, 2010), which characterizes the vast majority of cultural variation in suicide risk among ethnic and sexual minority groups. Psychometric properties showed that the CARS total and subscale scores demonstrated good internal consistency, convergent validity with scores on other suicide-related measures (the Suicide Ideation Scale, the Beck Depression Inventory suicide item, and the Beck Hopelessness Scale), and an ability to discriminate between participants with versus without history of suicide attempts. Regression analyses indicated that the CARS measure can be used with a general population, providing information predictive of suicidal behavior beyond that of minority status alone. Minorities, however, reported experiencing the CARS cultural risk factors to a greater extent than nonminorities, though effect sizes were small. Overall, results show that the CARS items are reliable, and the instrument identifies cultural suicide risk factors not previously attended to in suicide assessment. The CARS is the first to operationalize a systematic model that accounts for cultural competency across multiple cultural identities in suicide risk assessment efforts. PMID:23356681

  9. Estimation of Ten-Year Survival of Patients with Pulmonary Tuberculosis Based on the Competing Risks Model in Iran

    PubMed Central

    Kazempour-Dizaji, Mehdi; Tabarsi, Payam; Zayeri, Farid

    2016-01-01

    Background: Tuberculosis (TB) is a chronic bacterial disease, which despite the presence of effective drug strategies, still remains a serious health problem worldwide. Estimation of survival rate is an appropriate indicator for prognosis in patients with pulmonary TB. Therefore, this research was designed with the aim of accurate estimation of the survival of patients by taking both the death event and relapse into consideration. Materials and Methods: Based on a retrospective cohort study, information of 2,299 patients with pulmonary TB that had been referred to and treated in Masih Daneshvari Hospital from 2005 to 2015 was reviewed. To estimate the survival of patients with pulmonary TB, the competing risks model, which considered death and relapse as competing events, was used. In addition, the effect of factors affecting the cumulative incidence function (CIF) of death event and relapse was also examined. Results: The effect of risk factors on the CIF of death events and relapse showed that patients’ age, marital status, contact with TB patients, adverse effect of drugs, imprisonment and HIV positivity were factors that affected the CIF of death. Meanwhile, sex, marital status, imprisonment and HIV positivity were factors affecting the CIF of relapse (P <0.05). Considering death and relapse as competing events, survival estimation in pulmonary TB patients showed that survival in this group of patients in the first, third, fifth and tenth year after treatment was 39%, 14%, 7% and 0%, respectively. Conclusion: The use of competing risks model in survival analysis of patients with pulmonary TB with consideration of competing events, enables more accurate estimation of survival. PMID:27403177

  10. The LD Adolescent at Risk: Developmental Tasks, Social Competence, and Communication Effectiveness.

    ERIC Educational Resources Information Center

    Jackson, Moss A.

    1987-01-01

    Key developmental tasks of adolescence and the unique problems that face the learning-disabled adolescent are outlined, focusing on the role of social competency and communication effectiveness. Components of a comprehensive social competency training program include the nature of the learning disability, the affective-defensive pattern, adaptive…

  11. Transferable Competences of Young People with a High Dropout Risk in Vocational Training in Germany

    ERIC Educational Resources Information Center

    Frey, Andreas; Balzer, Lars; Ruppert, Jean-Jacques

    2014-01-01

    This paper examines whether the subjective beliefs on their competences of 409 trainees in machinery, sales, and logistics constitute a reliable and valid way to measure transferable competences. The analysis of results attributes satisfactory to good reliability values to the assessment procedure. Furthermore, it could be shown that young people…

  12. Competing risk models in reliability systems, a weibull distribution model with bayesian analysis approach

    NASA Astrophysics Data System (ADS)

    Iskandar, Ismed; Satria Gondokaryono, Yudi

    2016-02-01

    In reliability theory, the most important problem is to determine the reliability of a complex system from the reliability of its components. The weakness of most reliability theories is that the systems are described and explained as simply functioning or failed. In many real situations, the failures may be from many causes depending upon the age and the environment of the system and its components. Another problem in reliability theory is one of estimating the parameters of the assumed failure models. The estimation may be based on data collected over censored or uncensored life tests. In many reliability problems, the failure data are simply quantitatively inadequate, especially in engineering design and maintenance system. The Bayesian analyses are more beneficial than the classical one in such cases. The Bayesian estimation analyses allow us to combine past knowledge or experience in the form of an apriori distribution with life test data to make inferences of the parameter of interest. In this paper, we have investigated the application of the Bayesian estimation analyses to competing risk systems. The cases are limited to the models with independent causes of failure by using the Weibull distribution as our model. A simulation is conducted for this distribution with the objectives of verifying the models and the estimators and investigating the performance of the estimators for varying sample size. The simulation data are analyzed by using Bayesian and the maximum likelihood analyses. The simulation results show that the change of the true of parameter relatively to another will change the value of standard deviation in an opposite direction. For a perfect information on the prior distribution, the estimation methods of the Bayesian analyses are better than those of the maximum likelihood. The sensitivity analyses show some amount of sensitivity over the shifts of the prior locations. They also show the robustness of the Bayesian analysis within the range

  13. A competing risks approach for time estimation of household WEEE disposal.

    PubMed

    Gutiérrez, E; Adenso-Díaz, B; Lozano, S; González-Torre, P

    2010-01-01

    The recent growth in the number of electrical and electronic devices is viewed as one the priority waste streams in European Union waste management policy. This paper presents the findings of a survey to study domestic habits with respect to Waste Electrical and Electronic Equipment (WEEE) in Spain. A specific problem when performing this estimation arises from the fact that consumers quite often store old appliances at home when they are no longer used. Focusing on four different types of appliance, survival analysis (SA) is used to study both the usage span and the reasons for no longer using each device. The time that the discarded products were kept at home before being disposed of was studied using competing risks (CR) analysis. The results of the analysis provide information on the distribution of the studied variables for the different outcomes as well as the influence exerted by the socio-demographic variables considered. Relations between these characteristics and the storage time of the appliances before disposal emerge based on survey data. For instance, the CR model finds that the storage time of the some appliances (i.e. refrigerator) is related to these social-demographics factors. However, other appliances (i.e. microwave oven) are less influenced by these factors. The attitude and motivation of the respondents to the survey as regards the End-of-Life of appliances were also analysed. A majority of respondents do not store discarded appliances at home. The first reason for storing appliances at home is the possibility of it being useful in the future and the second that the respondents did not know what to do with them. PMID:20231083

  14. A competing risks approach for time estimation of household WEEE disposal

    SciTech Connect

    Gutierrez, E.; Adenso-Diaz, B.; Lozano, S.; Gonzalez-Torre, P.

    2010-08-15

    The recent growth in the number of electrical and electronic devices is viewed as one the priority waste streams in European Union waste management policy. This paper presents the findings of a survey to study domestic habits with respect to Waste Electrical and Electronic Equipment (WEEE) in Spain. A specific problem when performing this estimation arises from the fact that consumers quite often store old appliances at home when they are no longer used. Focusing on four different types of appliance, survival analysis (SA) is used to study both the usage span and the reasons for no longer using each device. The time that the discarded products were kept at home before being disposed of was studied using competing risks (CR) analysis. The results of the analysis provide information on the distribution of the studied variables for the different outcomes as well as the influence exerted by the socio-demographic variables considered. Relations between these characteristics and the storage time of the appliances before disposal emerge based on survey data. For instance, the CR model finds that the storage time of the some appliances (i.e. refrigerator) is related to these social-demographics factors. However, other appliances (i.e. microwave oven) are less influenced by these factors. The attitude and motivation of the respondents to the survey as regards the End-of-Life of appliances were also analysed. A majority of respondents do not store discarded appliances at home. The first reason for storing appliances at home is the possibility of it being useful in the future and the second that the respondents did not know what to do with them.

  15. Medical language proficiency: A discussion of interprofessional language competencies and potential for patient risk.

    PubMed

    Hull, Melodie

    2016-02-01

    In increasingly multilingual healthcare environments worldwide, ensuring accurate, effective communication is requisite. Language proficiency is essential, particularly medical language proficiency. Medical language is a universal construct in healthcare, the shared language of health and allied health professions. It is highly evolved, career-specific, technical and cultural-bound-a language for specific purposes. Its function differs significantly from that of a standard language. Proficiency requires at minimum, a common understanding of discipline-specific jargon, abstracts, euphemisms, abbreviations; acronyms. An optimal medical language situation demands a level of competency beyond the superficial wherein one can convey or interpret deeper meanings, distinguish themes, voice opinion, and follow directions precisely. It necessitates the use of clarity, and the ability to understand both lay and formal language-characteristics not essential to standard language. Proficiency influences professional discourse and can have the potential to positively or negatively affect patient outcomes. While risks have been identified when there is language discordance between care provider and patient, almost nothing has been said about this within care teams themselves. This article will do so in anticipation that care providers, regulators, employers, and researchers will acknowledge potential language-based communication barriers and work towards resolutions. This is predicated on the fact that the growing interest in language and communication in healthcare today appears to be rested in globalization and increasingly linguistically diverse patient populations. Consideration of the linguistically diverse healthcare workforce is absent. An argument will be posited that if potential risks to patient safety exist and there are potentials for disengagement from care by patients when health providers do not speak their languages then logically these language-based issues can

  16. Risk Management. Unit 20. Level 2. Instructor Guide. PACE: Program for Acquiring Competence in Entrepreneurship. Third Edition. Research & Development Series No. 302-20.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This instructor guide for a unit on risk management in the PACE (Program for Acquiring Competence in Entrepreneurship) curriculum includes the full text of the student module and lesson plans, instructional suggestions, and other teacher resources. The competencies that are incorporated into this module are at Level 2 of learning--planning for a…

  17. Risk.

    PubMed

    Cole, Stephen R; Hudgens, Michael G; Brookhart, M Alan; Westreich, Daniel

    2015-02-15

    The epidemiologist primarily studies transitions between states of health and disease. The purpose of the present article is to define a foundational parameter for such studies, namely risk. We begin simply and build to the setting in which there is more than 1 event type (i.e., competing risks or competing events), as well as more than 1 treatment or exposure level of interest. In the presence of competing events, the risks are a set of counterfactual cumulative incidence functions for each treatment. These risks can be depicted visually and summarized numerically. We use an example from the study of human immunodeficiency virus to illustrate concepts. PMID:25660080

  18. Estimating and comparing time-dependent areas under receiver operating characteristic curves for censored event times with competing risks.

    PubMed

    Blanche, Paul; Dartigues, Jean-François; Jacqmin-Gadda, Hélène

    2013-12-30

    The area under the time-dependent ROC curve (AUC) may be used to quantify the ability of a marker to predict the onset of a clinical outcome in the future. For survival analysis with competing risks, two alternative definitions of the specificity may be proposed depending of the way to deal with subjects who undergo the competing events. In this work, we propose nonparametric inverse probability of censoring weighting estimators of the AUC corresponding to these two definitions, and we study their asymptotic properties. We derive confidence intervals and test statistics for the equality of the AUCs obtained with two markers measured on the same subjects. A simulation study is performed to investigate the finite sample behaviour of the test and the confidence intervals. The method is applied to the French cohort PAQUID to compare the abilities of two psychometric tests to predict dementia onset in the elderly accounting for death without dementia competing risk. The 'timeROC' R package is provided to make the methodology easily usable. PMID:24027076

  19. Twitter as a Potential Disaster Risk Reduction Tool. Part IV: Competency-based Education and Training Guidelines to Promote Community Resiliency.

    PubMed

    Yeager, Violet; Cooper, Guy Paul; Burkle, Frederick M; Subbarao, Italo

    2015-01-01

    Twitter can be an effective tool for disaster risk reduction but gaps in education and training exist in current public health and disaster management educational competency standards.  Eleven core public health and disaster management competencies are proposed that incorporate Twitter as a tool for effective disaster risk reduction.  Greater funding is required to promote the education and training of this tool for those in professional schools and in the current public health and disaster management workforce. PMID:26203398

  20. Risk communication as a core public health competence in infectious disease management: Development of the ECDC training curriculum and programme.

    PubMed

    Dickmann, Petra; Abraham, Thomas; Sarkar, Satyajit; Wysocki, Piotr; Cecconi, Sabrina; Apfel, Franklin; Nurm, Ülla-Karin

    2016-01-01

    Risk communication has been identified as a core competence for guiding public health responses to infectious disease threats. The International Health Regulations (2005) call for all countries to build capacity and a comprehensive understanding of health risks before a public health emergency to allow systematic and coherent communication, response and management. Research studies indicate that while outbreak and crisis communication concepts and tools have long been on the agenda of public health officials, there is still a need to clarify and integrate risk communication concepts into more standardised practices and improve risk communication and health, particularly among disadvantaged populations. To address these challenges, the European Centre for Disease Prevention and Control (ECDC) convened a group of risk communication experts to review and integrate existing approaches and emerging concepts in the development of a training curriculum. This curriculum articulates a new approach in risk communication moving beyond information conveyance to knowledge- and relationship-building. In a pilot training this approach was reflected both in the topics addressed and in the methods applied. This article introduces the new conceptual approach to risk communication capacity building that emerged from this process, presents the pilot training approach developed, and shares the results of the course evaluation. PMID:27103616

  1. Instructional Climates in Preschool Children Who Are At-Risk. Part II: Perceived Physical Competence

    ERIC Educational Resources Information Center

    Robinson, Leah E.; Rudisill, Mary E.; Goodway, Jacqueline D.

    2009-01-01

    In Part II of this study, we examined the effect of two 9-week instructional climates (low-autonomy [LA] and mastery motivational climate [MMC]) on perceived physical competence (PPC) in preschoolers (N = 117). Participants were randomly assigned to an LA, MMC, or comparison group. PPC was assessed by a pretest, posttest, and retention test with…

  2. Enhancing Parental Competencies for High Risk Mothers: An Evaluation of Prevention Effects.

    ERIC Educational Resources Information Center

    Resnick, Gary

    1985-01-01

    A 3-year study examined effects of two prevention programs (life-skills esteem-building and life-skills parent-training) for sole-support mothers with school-aged children. Lack of competency enhancement effects appeared to be a function of reduced exposure to the interventions. There was no support for connections between short-term competency…

  3. Risk and Protective Factors for Children of Adolescents: Maternal Depression and Parental Sense of Competence

    ERIC Educational Resources Information Center

    Knoche, Lisa L.; Givens, Jami E.; Sheridan, Susan M.

    2007-01-01

    We investigated the relationship between depression and parental sense of competence to child cognitive outcomes for a sample of 49 adolescent mothers and their young children ("Mean age" = 9 1/2 months) enrolled in a student parenting program. Cognitive development of the infants and toddlers was assessed using the Bayley Scales of Infant…

  4. Core Competency Modification. A Manual for Working with At-Risk/Special Needs Students.

    ERIC Educational Resources Information Center

    Loess Hills Area Education Agency 13, Council Bluffs, IA.

    This manual assists teachers in providing adaptations for disabled and disadvantaged students to ensure their success in the regular vocational classroom and to meet requirements of the new vocational education standards in Iowa, which call for a competency-based curriculum. Introductory pages include strategies for teaching special needs…

  5. Clinical-Pathological Characteristics and Prognosis of a Cohort of Oesophageal Cancer Patients: a Competing Risks Survival Analysis

    PubMed Central

    Rodríguez-Camacho, Elena; Pita-Fernández, Salvador; Pértega-Díaz, Sonia; López-Calviño, Beatriz; Seoane-Pillado, Teresa

    2015-01-01

    Background To determine the clinical course, follow-up strategies, and survival of oesophageal cancer patients using a competing risks survival analysis. Methods We conducted a retrospective and prospective follow-up study. The study included 180 patients with a pathological diagnosis of oesophageal cancer in A Coruña, Spain, between 2003 and 2008. The Kaplan-Meier methodology and competing risks survival analysis were used to calculate the specific survival rate. The study was approved by the Ethics Review Board (code 2011/372, CEIC Galicia). Results The specific survival rate at the first, third, and fifth years was 40.2%, 18.1%, and 12.4%, respectively. Using the Kaplan-Meier methodology, the survival rate was slightly higher after the third year of follow-up. In the multivariate analysis, poor prognosis factors were female sex (hazard ratio [HR] 1.94; 95% confidence interval [CI], 1.24–3.03), Charlson’s comorbidity index (HR 1.17; 95% CI, 1.02–1.33), and stage IV tumours (HR 1.70; 95% CI, 1.11–2.59). The probability of dying decreased with surgical and oncological treatment (chemotherapy and/or radiotherapy) (HR 0.23; 95% CI, 0.12–0.45). The number of hospital consultations per year during the follow-up period, from diagnosis to the appearance of a new event (local recurrences, newly appeared metastasis, and newly appeared neoplasias) did not affect the probability of survival (HR 1.03; 95% CI, 0.92–1.15). Conclusions The Kaplan-Meier methodology overestimates the survival rate in comparison to competing risks analysis. The variables associated with a poor prognosis are female sex, Charlson’s comorbidity score and extensive tumour invasion. Type of follow-up strategy employed after diagnosis does not affect the prognosis of the disease. PMID:25716135

  6. A Competence-Based Science Learning Framework Illustrated Through the Study of Natural Hazards and Disaster Risk Reduction

    NASA Astrophysics Data System (ADS)

    Oyao, Sheila G.; Holbrook, Jack; Rannikmäe, Miia; Pagunsan, Marmon M.

    2015-09-01

    This article proposes a competence-based learning framework for science teaching, applied to the study of 'big ideas', in this case to the study of natural hazards and disaster risk reduction (NH&DRR). The framework focuses on new visions of competence, placing emphasis on nurturing connectedness and behavioral actions toward resilience and sustainability. The framework draws together competences familiarly expressed as cognitive knowledge and skills, plus dispositions and adds connectedness and action-related behaviors, and applies this by means of a progression shift associated with NH&DRR from abilities to capabilities. The target is enhanced scientific literacy approached through an education through science focus, amplified through the study of a big idea, promotion of sustained resilience in the face of disaster and the taking of responsibilities for behavioral actions. The framework is applied to a learning progression for each interrelated education dimension, thus serving as a guide for both the development of abilities and as a platform for stimulating student capabilities within instruction and assessment.

  7. Risks, dangers and competing clinical decisions on venous thromboembolism prophylaxis in hospital care.

    PubMed

    Boiko, Olga; Sheaff, Rod; Child, Susan; Gericke, Christian A

    2014-07-01

    Drawing on wider sociologies of risk, this article examines the complexity of clinical risks and their management, focusing on risk management systems, expert decision-making and safety standards in health care. At the time of this study preventing venous thromboembolism (VTE) among in-patients was one of the top priorities for hospital safety in the English National Health Service (NHS). An analysis of 50 interviews examining hospital professionals' perceptions about VTE risks and prophylaxis illuminates how National Institute for Health and Clinical Excellence (NICE) guidelines influenced clinical decision-making in four hospitals in one NHS region. We examine four themes: the identification of new risks, the institutionalisation and management of risk, the relationship between risk and danger and the tensions between risk management systems and expert decision-making. The implementation of NICE guidelines for VTE prevention extended managerial control over risk management but some irreducible clinical dangers remained that were beyond the scope of the new VTE risk management systems. Linking sociologies of risk with the realities of hospital risk management reveals the capacity of these theories to illuminate both the possibilities and the limits of managerialism in health care. PMID:24635764

  8. Conceptualizing and Re-Evaluating Resilience across Levels of Risk, Time, and Domains of Competence

    ERIC Educational Resources Information Center

    Vanderbilt-Adriance, Ella; Shaw, Daniel S.

    2008-01-01

    This article examines potential theoretical constraints on resilience across levels of risk, time, and domain of outcome. Studies of resilience are reviewed as they relate to the prevalence of resilience across levels of risk (e.g., single life events vs. cumulative risk), time, and domains of adjustment. Based on a thorough review of pertinent…

  9. Parametric mapping

    NASA Astrophysics Data System (ADS)

    Branch, Allan C.

    1998-01-01

    Parametric mapping (PM) lies midway between older and proven artificial landmark based guidance systems and yet to be realized vision based guidance systems. It is a simple yet effective natural landmark recognition system offering freedom from the need for enhancements to the environment. Development of PM systems can be inexpensive and rapid and they are starting to appear in commercial and industrial applications. Together with a description of the structural framework developed to generically describe robot mobility, this paper illustrates clearly the parts of any mobile robot navigation and guidance system and their interrelationships. Among other things, the importance of the richness of the reference map, and not necessarily the sensor map, is introduced, the benefits of dynamic path planners to alleviate the need for separate object avoidance, and the independence of the PM system to the type of sensor input is shown.

  10. How Enrollment Ends: Analyzing the Correlates of Student Graduation, Transfer and Dropout with a Competing Risks Model. AIR 1995 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Ronco, Sharron L.

    This study applied the methodology of competing risks survival analysis to determine the probability that a student's first enrollment in the university will end in graduation, transfer, or withdrawal. The risk factors associated with each mode of exit were assessed, with attention to factors such as admission status, full-time or part-time…

  11. Conceptualizing and Re-Evaluating Resilience Across Levels of Risk, Time, and Domains of Competence

    PubMed Central

    Shaw, Daniel S.

    2009-01-01

    This article examines potential theoretical constraints on resilience across levels of risk, time, and domain of outcome. Studies of resilience are reviewed as they relate to the prevalence of resilience across levels of risk (e.g., single life events vs. cumulative risk), time, and domains of adjustment. Based on a thorough review of pertinent literature, we conclude that resilience, as a global construct, appears to be rare at the highest levels of risk, and that resilience may benefit from a narrower conceptualization focusing on specific outcomes at specific timepoints in development. The implication of this conclusion for future research and intervention efforts is then discussed. PMID:18379875

  12. The Relation Between Adolescent Social Competence and Young Adult Delinquency and Educational Attainment Among At-Risk Youth: The Mediating Role of Peer Delinquency

    PubMed Central

    Stepp, Stephanie D; Pardini, Dustin A; Loeber, Rolf; Morris, Nancy A

    2015-01-01

    Objective We examined trajectories of adolescent social competence as a resilience factor among at-risk youth. To examine potential mechanisms of this resilience process, we investigated the putative mediating effect of peer delinquency on the relation between adolescent social competence and young adult delinquency seriousness and educational attainment. Method Participants (n = 257) were screened to be at risk for antisocial behaviour at age 13 years. Data were derived from an ongoing longitudinal study of the development of antisocial and delinquent behaviour among inner-city boys, the Pittsburgh Youth Study. We used data collected from participants when aged 13 years until they were aged 25.5 years for our study. Results Results indicated that boys with high levels of social competence decreased their involvement with deviant peers throughout adolescence, which, in turn, predicted less serious forms of delinquency in early adulthood. Social competence had a direct effect on educational attainment in early adulthood, as boys who developed social competencies in adolescence went further in school irrespective of their involvement with delinquent peers. Conclusions Results suggest that promoting the development of social competencies and reducing involvement with delinquent peers will protect at-risk youth from engaging in serious delinquency in early adulthood while increasing their educational success. PMID:21878156

  13. Chronic Graft Loss and Death in Patients With Post-Transplant Malignancy in Living Kidney Transplantation: A Competing Risk Analysis

    PubMed Central

    Salesi, Mahmoud; Rostami, Zohreh; Rahimi Foroushani, Abbas; Mehrazmay, Ali Reza; Mohammadi, Jamile; Einollahi, Behzad; Asgharian, Saeed; Eshraghian, Mohammad Reza

    2014-01-01

    Background: Malignancy is a common complication after renal transplantation. Death with functioning graft and chronic graft loss are two competing outcomes in patients with post-transplant malignancies. Objectives: The purpose of our study was to evaluate the risk factors associated with cumulative incidence of these two outcomes. Patients and Methods: Fine-Gray model was used for 266 cases with post-transplant malignancy in Iran. These patients were followed-up from the diagnosis until the date of last visit, chronic graft loss, or death, subsequently. Results: At the end of the study, as competing events, chronic graft loss and death with functioning graft were seen in 27 (10.2%) and 53 cases (19.9%), respectively, while 186 cases (69.9%) were accounted as censored. The incidence rate of death was approximately two-time of the incidence rate of chronic graft loss (8.6 vs. 4.4 per 100 person-years). In multivariate analysis, significant risk factors associated with cumulative incidence of death included age (P < 0.007, subhazard ratio (SHR) = 1.03), type of cancer (P < 0.0001), and response to treatment (P < 0.0001, SHR = 0.027). The significant risk factors associated with cumulative incidence of chronic graft loss were gender (P = 0.05, SHR = 0.37), treatment modality (P < 0.0001), and response to treatment (P = 0.048, SHR = 0.47). Conclusions: Using these factors, nephrologists may predict the occurrence of graft loss or death. If the probability of graft loss was higher, physicians can decrease the immunosuppressive medications dosage to decrease the incidence of graft loss. PMID:25032129

  14. Prediction of skull fracture risk for children 0-9 months old through validated parametric finite element model and cadaver test reconstruction.

    PubMed

    Li, Zhigang; Liu, Weiguo; Zhang, Jinhuan; Hu, Jingwen

    2015-09-01

    Skull fracture is one of the most common pediatric traumas. However, injury assessment tools for predicting pediatric skull fracture risk is not well established mainly due to the lack of cadaver tests. Weber conducted 50 pediatric cadaver drop tests for forensic research on child abuse in the mid-1980s (Experimental studies of skull fractures in infants, Z Rechtsmed. 92: 87-94, 1984; Biomechanical fragility of the infant skull, Z Rechtsmed. 94: 93-101, 1985). To our knowledge, these studies contained the largest sample size among pediatric cadaver tests in the literature. However, the lack of injury measurements limited their direct application in investigating pediatric skull fracture risks. In this study, 50 pediatric cadaver tests from Weber's studies were reconstructed using a parametric pediatric head finite element (FE) model which were morphed into subjects with ages, head sizes/shapes, and skull thickness values that reported in the tests. The skull fracture risk curves for infants from 0 to 9 months old were developed based on the model-predicted head injury measures through logistic regression analysis. It was found that the model-predicted stress responses in the skull (maximal von Mises stress, maximal shear stress, and maximal first principal stress) were better predictors than global kinematic-based injury measures (peak head acceleration and head injury criterion (HIC)) in predicting pediatric skull fracture. This study demonstrated the feasibility of using age- and size/shape-appropriate head FE models to predict pediatric head injuries. Such models can account for the morphological variations among the subjects, which cannot be considered by a single FE human model. PMID:25900622

  15. Reducing psychosocial risks through supervisors' development: a contribution for a brief version of the "Stress Management Competency Indicator Tool".

    PubMed

    Toderi, Stefano; Gaggia, Andrea; Balducci, Cristian; Sarchielli, Guido

    2015-06-15

    With the recent changes in the world of work psychosocial risks are increasingly prevalent, causing work stress and physical and mental illnesses, which have a tremendous impact on public health and social participation. Supervisors' behaviour development was proposed as an innovative intervention that can reduce psychosocial risks. The "Stress Management Competency Indicator Tool" is one of the most important questionnaires that assess managers' preventive behaviour. However, its psychometric properties have never been evaluated and the length of the questionnaire (66 items) limits its practical applicability. The aim of this study was to contribute to the development of the questionnaire by providing psychometric evidence on a brief version of the tool focusing on the "Managing and Communicating existing and future Work" cluster of behaviours, which has been found to be the crucial one in terms of stress prevention. A questionnaire was administered to 178 employees of two Italian public organizations (a municipality and a hospital), measuring the supervisors' "Managing and Communicating existing and future Work" competency, and the affective well-being and work team effectiveness. The results showed excellent psychometric properties of the supervisors' behaviour scale and confirmed the expected relationships with criterion outcomes (affective well-being and team effectiveness). Overall, the factorial structure and dimensionality, the construct validity and reliability, and the concurrent validity of the tool were strongly supported by this study. We concluded that the brief version of the scale is a valid and reliable measure that can be easily used in practice and that can contribute to the development of research and practice on this topic. PMID:25770947

  16. Comprehensive outcomes of on- and off-antiviral prophylaxis in hepatitis B patients undergoing cancer chemotherapy: A competing risks analysis.

    PubMed

    An, Jihyun; Shim, Ju Hyun; Kim, Seon-Ok; Choi, Jonggi; Kim, Sang-We; Lee, Danbi; Kim, Kang Mo; Lim, Young-Suk; Lee, Han Chu; Chung, Young-Hwa; Lee, Yung Sang; Suh, Dong Jin

    2016-09-01

    Although antiviral prophylaxis is essential in hepatitis B patients in the context of cancer chemotherapy, there is little evidence-based consensus regarding the appropriate prevention strategy depending on the underlying type of cancer and viral status. This retrospective study included a comprehensive cohort of 302 hepatitis B surface antigen-positive patients with various cancers undergoing chemotherapy and antiviral prophylaxis. The rates of hepatitis B virus (HBV) reactivation during antiviral therapy (>1 log10 IU/mL increase or positive conversion of serum HBV DNA) and relapse when off antivirals ([re]appearance of HBV DNA >2,000 IU/ml with related alanine aminotransferase elevation) were evaluated, together with the associated risk factors, in a competing risks analysis where cancer death was considered as the competing event. During antiviral prophylaxis, HBV was reactivated in six patients (1.9%), who had leukemia (n = 4) or lymphoma (n = 2) and were treated with lamivudine (n = 4) or entecavir (n = 2). The incidence rate of HBV relapse in 127 off-prophylaxis patients was 21.3% during a median post-antiviral period of 11.7 months. Lymphoma, pre-prophylactic HBV DNA ≥2,000 IU/ml, and age ≥50 years were independent predictors of off-treatment HBV relapse (adjusted hazard ratios 5.25, 3.07, and 0.34, respectively; Ps < 0.05). Antiviral and anticancer drugs, duration of consolidation on antiviral prophylaxis, and HBeAg positivity were not independent predictors. In conclusion, hepatitis B flare-ups are not rare in patients receiving cancer chemotherapy during and after anti-HBV prophylaxis, even when potent antivirals are used. Patients with hematopoietic or lymphoid neoplasms or high viral burdens should receive prolonged and powerful HBV prophylaxis. J. Med. Virol. 88:1576-1586, 2016. © 2016 Wiley Periodicals, Inc. PMID:26945543

  17. Eating competence of elderly Spanish adults is associated with a healthy diet and a favorable cardiovascular disease risk profile.

    PubMed

    Lohse, Barbara; Psota, Tricia; Estruch, Ramón; Zazpe, Itziar; Sorli, José V; Salas-Salvadó, Jordi; Serra, Mercè; Krall, Jodi Stotts; Márquez, Fabiola; Ros, Emilio

    2010-07-01

    Eating competence (EC), a bio-psychosocial model for intrapersonal approaches to eating and food-related behaviors, is associated with less weight dissatisfaction, lower BMI, and increased HDL-cholesterol in small U.S. studies, but its relationship to nutrient quality and overall cardiovascular risk have not been examined. Prevención con Dieta Mediterránea (PREDIMED) is a 5-y controlled clinical trial evaluating Mediterranean diet efficacy on the primary prevention of cardiovascular diseases (CVD) in Spain. In a cross-sectional study, 638 PREDIMED participants (62% women, mean age 67 y) well phenotyped for cardiovascular risk factors were assessed for food intake and EC using validated questionnaires. Overall, 45.6% were eating-competent. EC was associated with being male and energy intake (P < 0.01). After gender and energy adjustment, participants with EC compared with those without showed higher fruit intake and greater adherence to the Mediterranean diet (P < 0.05) and tended to consume more fish (P = 0.076) and fewer dairy products (P = 0.054). EC participants tended to have a lower BMI (P = 0.057) and had a lower fasting blood glucose concentration and serum LDL-:HDL-cholesterol ratio (P < 0.05) and a higher HDL-cholesterol concentration (P = 0.025) after gender adjustment. EC participants had lower odds ratios (OR) of having a blood glucose concentration >5.6 mmol/L (0.71; 95% CI 0.51-0.98) and HDL-cholesterol <1.0 mmol/L (0.70; 95% CI 0.68-1.00). The OR of actively smoking, being obese, or having a serum LDL-cholesterol concentration > or =3.4 mmol/L were <1.0, but the 95% CI included the 1.0 (P > 0.1). Our findings support further examination of EC as a strategy for enhancing diet quality and CVD prevention. PMID:20505016

  18. Resilience and Risk Competence in Schools: Theory/Knowledge and International Application in Project REBOUND

    ERIC Educational Resources Information Center

    Brown, Joel H.; Jean-Marie, Gaetane; Beck, Jerome

    2010-01-01

    Despite a 50-year interdisciplinary and longitudinal research legacy--showing that nearly 80% of young people considered most "at risk" thrive by midlife--only recently have practitioners/researchers engaged in the explicit, prospective facilitation of "resilience" in educational settings. Here, theory/knowledge distinguishing and extending risk…

  19. Socioenvironmental Risk and Adjustment in Latino Youth: The Mediating Effects of Family Processes and Social Competence

    ERIC Educational Resources Information Center

    Prelow, Hazel M.; Loukas, Alexandra; Jordan-Green, Lisa

    2007-01-01

    The direct and mediated effects of socioenvironmental risk on internalizing and externalizing problems among Latino youth aged 10-14 were examined using prospective analyses. Participants in this study were 464 Latino mother and child dyads surveyed as part of the "Welfare, Children & Families: A Three City Study." It was hypothesized that…

  20. A Multivariate Investigation of Maternal Risks and Their Relationship to Low-Income, Preschool Children's Competencies

    ERIC Educational Resources Information Center

    Perry, Marlo A.; Fantuzzo, John W.

    2010-01-01

    Utilizing a developmental-ecological framework, the purpose of this study was to understand the unique impact of multiple maternal risks across time on ethnically diverse, low-income, preschool children's cognitive skills, pro-social behaviors, and behavior problems. Additionally, this study sought to understand the variability of maternal risks…

  1. The EARLY ALLIANCE prevention trial: an integrated set of interventions to promote competence and reduce risk for conduct disorder, substance abuse, and school failure.

    PubMed

    Dumas, J E; Prinz, R J; Smith, E P; Laughlin, J

    1999-03-01

    Describes the EARLY ALLIANCE interventions, an integrated set of four programs designed to promote competence and reduce risk for early-onset conduct disorder, substance abuse, and school failure. These interventions are evaluated as part of a prevention trial that begins at school entry and targets child functioning and socializing practices across multiple contexts (school, peer group, family) and multiple domains (affective, social, and achievement coping-competence). The paper presents the conceptual foundation of the four interventions, including a synopsis of the risk and protective factors associated with conduct disorder and related outcomes, and of the coping-competence model driving EARLY ALLIANCE. The developmental rationale, intended impact, and procedures are described for each intervention: a universally administered classroom program and indicated, peer, reading-mentoring, and family programs. Interventions are currently being tested in a prevention trial, which is briefly summarized. PMID:11324096

  2. Competence, Self-Esteem, and Coping Efficacy as Mediators of Ecological Risk and Depressive Symptoms in Urban African American and European American Youth

    ERIC Educational Resources Information Center

    Prelow, Hazel M.; Weaver, Scott R.; Swenson, Rebecca R.

    2006-01-01

    Structural equation modeling was used to test [Sandler, "American Journal of Community Psychology" 29: 19-61.] a theoretical model of risk and resilience in an urban sample of African American and European American adolescents. The aims of the present study were to examine whether self-system processes (i.e., competence, self-esteem, and coping…

  3. Competing-Risks Mortality After Radiotherapy vs. Observation for Localized Prostate Cancer: A Population-based Study

    SciTech Connect

    Abdollah, Firas; Sun, Maxine; Schmitges, Jan; Thuret, Rodolphe; Tian, Zhe; Shariat, Shahrokh F.; Briganti, Alberto; Jeldres, Claudio; Perrotte, Paul; Montorsi, Francesco; Karakiewicz, Pierre I.

    2012-09-01

    Purpose: Contemporary patients with localized prostate cancer (PCa) are more frequently treated with radiotherapy. However, there are limited data on the effect of this treatment on cancer-specific mortality (CSM). Our objective was to test the relationship between radiotherapy and survival in men with localized PCa and compare it with those treated with observation. Methods: A population-based cohort identified 68,797 men with cT1-T2 PCa treated with radiotherapy or observation between the years 1992 and 2005. Propensity-score matching was used to minimize potential bias related to treatment assignment. Competing-risks analyses tested the effect of treatment type (radiotherapy vs. observation) on CSM, after accounting to other-cause mortality. All analyses were carried out within PCa risk, baseline comorbidity status, and age groups. Results: Radiotherapy was associated with more favorable 10-year CSM rates than observation in patients with high-risk PCa (8.8 vs. 14.4%, hazard ratio [HR]: 0.59, 95% confidence interval [CI]: 0.50-0.68). Conversely, the beneficial effect of radiotherapy on CSM was not evident in patients with low-intermediate risk PCa (3.7 vs. 4.1%, HR: 0.91, 95% CI: 0.80-1.04). Radiotherapy was beneficial in elderly patients (5.6 vs. 7.3%, HR: 0.70, 95% CI: 0.59-0.80). Moreover, it was associated with improved CSM rates among patients with no comorbidities (5.7 vs. 6.5%, HR: 0.81, 95% CI: 0.67-0.98), one comorbidity (4.6 vs. 6.0%, HR: 0.87, 95% CI: 0.75-0.99), and more than two comorbidities (4.2 vs. 5.0%, HR: 0.79, 95% CI: 0.65-0.96). Conclusions: Radiotherapy substantially improves CSM in patients with high-risk PCa, with little or no benefit in patients with low-/intermediate-risk PCa relative to observation. These findings must be interpreted within the context of the limitations of observational data.

  4. Intensity-Modulated Radiotherapy for Craniospinal Irradiation: Target Volume Considerations, Dose Constraints, and Competing Risks

    SciTech Connect

    Parker, William Filion, Edith; Roberge, David; Freeman, Carolyn R.

    2007-09-01

    Purpose: To report the results of an analysis of dose received to tissues and organs outside the target volume, in the setting of spinal axis irradiation for the treatment of medulloblastoma, using three treatment techniques. Methods and Materials: Treatment plans (total dose, 23.4 Gy) for a standard two-dimensional (2D) technique, a three-dimensional (3D) technique using a 3D imaging-based target volume, and an intensity-modulated radiotherapy (IMRT) technique, were compared for 3 patients in terms of dose-volume statistics for target coverage, as well as organ at risk (OAR) and overall tissue sparing. Results: Planning target volume coverage and dose homogeneity was superior for the IMRT plans for V{sub 95%} (IMRT, 100%; 3D, 96%; 2D, 98%) and V{sub 107%} (IMRT, 3%; 3D, 38%; 2D, 37%). In terms of OAR sparing, the IMRT plan was better for all organs and whole-body contour when comparing V{sub 10Gy}, V{sub 15Gy}, and V{sub 20Gy}. The 3D plan was superior for V{sub 5Gy} and below. For the heart and liver in particular, the IMRT plans provided considerable sparing in terms of V{sub 10Gy} and above. In terms of the integral dose, the IMRT plans were superior for liver (IMRT, 21.9 J; 3D, 28.6 J; 2D, 38.6 J) and heart (IMRT, 9 J; 3D, 14.1J; 2D, 19.4 J), the 3D plan for the body contour (IMRT, 349 J; 3D, 337 J; 2D, 555 J). Conclusions: Intensity-modulated radiotherapy is a valid treatment option for spinal axis irradiation. We have shown that IMRT results in sparing of organs at risk without a significant increase in integral dose.

  5. Sparse representation of multi parametric DCE-MRI features using K-SVD for classifying gene expression based breast cancer recurrence risk

    NASA Astrophysics Data System (ADS)

    Mahrooghy, Majid; Ashraf, Ahmed B.; Daye, Dania; Mies, Carolyn; Rosen, Mark; Feldman, Michael; Kontos, Despina

    2014-03-01

    We evaluate the prognostic value of sparse representation-based features by applying the K-SVD algorithm on multiparametric kinetic, textural, and morphologic features in breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). K-SVD is an iterative dimensionality reduction method that optimally reduces the initial feature space by updating the dictionary columns jointly with the sparse representation coefficients. Therefore, by using K-SVD, we not only provide sparse representation of the features and condense the information in a few coefficients but also we reduce the dimensionality. The extracted K-SVD features are evaluated by a machine learning algorithm including a logistic regression classifier for the task of classifying high versus low breast cancer recurrence risk as determined by a validated gene expression assay. The features are evaluated using ROC curve analysis and leave one-out cross validation for different sparse representation and dimensionality reduction numbers. Optimal sparse representation is obtained when the number of dictionary elements is 4 (K=4) and maximum non-zero coefficients is 2 (L=2). We compare K-SVD with ANOVA based feature selection for the same prognostic features. The ROC results show that the AUC of the K-SVD based (K=4, L=2), the ANOVA based, and the original features (i.e., no dimensionality reduction) are 0.78, 0.71. and 0.68, respectively. From the results, it can be inferred that by using sparse representation of the originally extracted multi-parametric, high-dimensional data, we can condense the information on a few coefficients with the highest predictive value. In addition, the dimensionality reduction introduced by K-SVD can prevent models from over-fitting.

  6. Evaluating predictors of competing risk outcomes when censoring depends on time-dependent covariates, with application to safety and efficacy of HIV treatment.

    PubMed

    Lok, Judith J; Hughes, Michael D

    2016-06-15

    We propose a prediction model for the cumulative incidence functions of competing risks, based on a logit link. Because of a concern about censoring potentially depending on time-varying covariates in our motivating human immunodeficiency virus (HIV) application, we describe an approach for estimating the parameters in the prediction models using inverse probability of censoring weighting under a missingness at random assumption. We then illustrate the application of this methodology to identify predictors of the competing outcomes of virologic failure, an efficacy outcome, and treatment limiting adverse event, a safety outcome, among human immunodeficiency virus-infected patients first starting antiretroviral treatment. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26763556

  7. Parametric Cost Deployment

    NASA Technical Reports Server (NTRS)

    Dean, Edwin B.

    1995-01-01

    Parametric cost analysis is a mathematical approach to estimating cost. Parametric cost analysis uses non-cost parameters, such as quality characteristics, to estimate the cost to bring forth, sustain, and retire a product. This paper reviews parametric cost analysis and shows how it can be used within the cost deployment process.

  8. Negotiating competency, professionalism and risk: the integration of complementary and alternative medicine by nurses and midwives in NHS hospitals.

    PubMed

    Cant, Sarah; Watts, Peter; Ruston, Annmarie

    2011-02-01

    This qualitative interview study examined the use of complementary and alternative medicine (CAM) by nurses and midwives in NHS hospital settings in 2008 in the UK. It showed that the groundswell of interest in CAM in the 1990s had diminished by this time due to changes to policy and funding, and increasingly stringent clinical governance. Nevertheless, CAM provided an opportunity for committed and self-motivated practitioners to extend their therapeutic repertoire and develop affective dimensions of practice. However, the integration of CAM did not afford the autonomy, status and material gains traditionally associated with a collective professional project. In practice, occupational strategies were individualistic, and grounded in the assertion of competency through expressions of professionalism rather than the credentialism which underpins classic professionalisation. Central to these strategies was CAM related risk, which became a means by which to claim occupational space. However, the extent to which the adoption of CAM enhanced the nurses' and midwives' roles was limited by traditional medical authority; the uncertain status of CAM knowledge; and the absence of collective strategies - which together often left practitioners in a position of vulnerability. PMID:21208701

  9. Quantifying intrinsic and extrinsic control of single-cell fates in cancer and stem/progenitor cell pedigrees with competing risks analysis.

    PubMed

    Cornwell, J A; Hallett, R M; der Mauer, S Auf; Motazedian, A; Schroeder, T; Draper, J S; Harvey, R P; Nordon, R E

    2016-01-01

    The molecular control of cell fate and behaviour is a central theme in biology. Inherent heterogeneity within cell populations requires that control of cell fate is studied at the single-cell level. Time-lapse imaging and single-cell tracking are powerful technologies for acquiring cell lifetime data, allowing quantification of how cell-intrinsic and extrinsic factors control single-cell fates over time. However, cell lifetime data contain complex features. Competing cell fates, censoring, and the possible inter-dependence of competing fates, currently present challenges to modelling cell lifetime data. Thus far such features are largely ignored, resulting in loss of data and introducing a source of bias. Here we show that competing risks and concordance statistics, previously applied to clinical data and the study of genetic influences on life events in twins, respectively, can be used to quantify intrinsic and extrinsic control of single-cell fates. Using these statistics we demonstrate that 1) breast cancer cell fate after chemotherapy is dependent on p53 genotype; 2) granulocyte macrophage progenitors and their differentiated progeny have concordant fates; and 3) cytokines promote self-renewal of cardiac mesenchymal stem cells by symmetric divisions. Therefore, competing risks and concordance statistics provide a robust and unbiased approach for evaluating hypotheses at the single-cell level. PMID:27250534

  10. Quantifying intrinsic and extrinsic control of single-cell fates in cancer and stem/progenitor cell pedigrees with competing risks analysis

    PubMed Central

    Cornwell, J. A.; Hallett, R. M.; der Mauer, S. Auf; Motazedian, A.; Schroeder, T.; Draper, J. S.; Harvey, R. P.; Nordon, R. E.

    2016-01-01

    The molecular control of cell fate and behaviour is a central theme in biology. Inherent heterogeneity within cell populations requires that control of cell fate is studied at the single-cell level. Time-lapse imaging and single-cell tracking are powerful technologies for acquiring cell lifetime data, allowing quantification of how cell-intrinsic and extrinsic factors control single-cell fates over time. However, cell lifetime data contain complex features. Competing cell fates, censoring, and the possible inter-dependence of competing fates, currently present challenges to modelling cell lifetime data. Thus far such features are largely ignored, resulting in loss of data and introducing a source of bias. Here we show that competing risks and concordance statistics, previously applied to clinical data and the study of genetic influences on life events in twins, respectively, can be used to quantify intrinsic and extrinsic control of single-cell fates. Using these statistics we demonstrate that 1) breast cancer cell fate after chemotherapy is dependent on p53 genotype; 2) granulocyte macrophage progenitors and their differentiated progeny have concordant fates; and 3) cytokines promote self-renewal of cardiac mesenchymal stem cells by symmetric divisions. Therefore, competing risks and concordance statistics provide a robust and unbiased approach for evaluating hypotheses at the single-cell level. PMID:27250534

  11. Low Academic Competence in First Grade as a Risk Factor for Depressive Cognitions and Symptoms in Middle School

    ERIC Educational Resources Information Center

    Herman, Keith C.; Lambert, Sharon F.; Reinke, Wendy M.; Ialongo, Nicholas S.

    2008-01-01

    The present study investigated the role of low academic competence in the emergence of depressive cognitions and symptoms. Structural equation modeling was conducted on a longitudinal sample of African American boys (n = 253) and girls (n = 221). Results supported the hypothesized path models from academic competence in 1st grade to depressive…

  12. First incident hospitalisation for Australian women aged 70 and beyond: A 10 year examination using competing risks.

    PubMed

    Harris, Melissa L; Dolja-Gore, Xenia; Kendig, Hal; Byles, Julie E

    2016-01-01

    There are increasing concerns regarding high hospital use among older adults and the capacity to manage the economic impact of the ageing population trend on healthcare systems. First hospitalisation in old age may act as a catalyst for ongoing intensification of health problems and acute care use. This study examined factors associated with first incident hospitalisation in women aged over 70, accounting for the health inequalities associated with geographic location. Survey data from 3780 women from the 1921 to 1926 cohort of the Australian Longitudinal Study on Women's Health were matched with the Admitted Patients Data Collection and National Death Index. Days to first event (hospitalisation or death) were modelled using competing risks methods. A total of 3065 (80.3%) women had at least one hospital admission. More than half of the top 15 reasons for first hospitalisation were related to cardiovascular disease, with atrial fibrillation the most common. Proportional subdistribution hazards models showed that first hospital admission was driven by enabling and need factors including asthma/bronchitis diagnosis (HR=1.16; p=0.047), private health insurance (HR=1.16; p=0.004) more than two prescribed medications in previous month (HR=1.31; p=0.001), more than four general practitioner visits in previous year (HR=1.50; p=0.034), lower physical functioning (HR=0.99; p<0.001) and living in an inner regional area (HR=1.17; p=0.003). First overnight hospitalisation was primarily related with potentially preventable and treatable chronic diseases. Primary and secondary strategies aimed at chronic disease generally, and better chronic disease management particularly for cardiovascular and respiratory diseases, may play a vital role in disease prevention or delay in readmissions among this population. PMID:26952374

  13. The Prospective, Observational, Multicenter, Major Trauma Transfusion (PROMMTT) Study: Comparative Effectiveness of a Time-varying Treatment with Competing Risks

    PubMed Central

    Holcomb, John B.; del Junco, Deborah J.; Fox, Erin E.; Wade, Charles E.; Cohen, Mitchell J.; Schreiber, Martin A.; Alarcon, Louis H.; Bai, Yu; Brasel, Karen J.; Bulger, Eileen M.; Cotton, Bryan A.; Matijevic, Nena; Muskat, Peter; Myers, John G.; Phelan, Herb A.; White, Christopher E.; Zhang, Jiajie; Rahbar, Mohammad H.

    2013-01-01

    Context Hemorrhagic shock is the leading potentially preventable cause of death after injury. Transfusion of early and increased ratios of plasma and platelets to red blood cells (RBCs) has been associated with decreased mortality; however conflicting reports and the time-varying nature of transfusions and hemorrhagic death raise concern for the validity of the clinical conclusions drawn from the retrospective data. Objective To relate in-hospital mortality to: 1) early transfusion of plasma and/or platelets and 2) time-varying plasma:RBC and platelet:RBC ratios. Design Prospective cohort study documenting the timing of transfusions during active resuscitation and patient outcomes. Data were analyzed using time-dependent proportional hazards models. Setting Ten US Level 1 trauma centers. Patients Adult trauma patients surviving for 30 minutes after admission, transfused at least 1 unit RBC within 6 hours of admission (n=1245, the original study group) and at least 3 total units (of RBC, plasma or platelets) within 24 hours (n=905, the analysis group). Main outcome measure In-hospital mortality Results Plasma:RBC and platelet:RBC ratios were not constant over the first 24 hours (p<.001 for both). In a multivariable time-dependent Cox model, increased ratios of plasma:RBC (adjusted hazard ratio, HR=0.31, 95% CI=0.16–0.58) and platelets:RBC (adjusted HR=0.55, 95% CI=0.31–0.98) were independently associated with decreased 6-hour mortality, when hemorrhagic death predominated. In the first 6 hours, patients with ratios < 1:2 were 3–4 times more likely to die than patients with ratios ≥1:1. After 24 hours, plasma and platelet ratios were unassociated with mortality, when competing risks from non-hemorrhagic causes prevailed. Conclusions Higher plasma and platelet ratios early in resuscitation were associated with decreased mortality in patients transfused at least three units of blood products during the first 24 hours after admission. Among survivors at 24 hours

  14. Competency Index. [Health Technology Cluster.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This competency index lists the competencies included in the 62 units of the Tech Prep Competency Profiles within the Health Technologies Cluster. The unit topics are as follows: employability skills; professionalism; teamwork; computer literacy; documentation; infection control and risk management; medical terminology; anatomy, physiology, and…

  15. Analyzing Factors Affecting Emergency Department Length of Stay-Using a Competing Risk-accelerated Failure Time Model.

    PubMed

    Chaou, Chung-Hsien; Chiu, Te-Fa; Yen, Amy Ming-Fang; Ng, Chip-Jin; Chen, Hsiu-Hsi

    2016-04-01

    Emergency department (ED) length of stay (LOS) is associated with ED crowding and related complications. Previous studies either analyzed single patient disposition groups or combined different endpoints as a whole. The aim of this study is to evaluate different effects of relevant factors affecting ED LOS among different patient disposition groups.This is a retrospective electronic data analysis. The ED LOS and relevant covariates of all patients between January 2013 and December 2013 were collected. A competing risk accelerated failure time model was used to compute endpoint type-specific time ratios (TRs) for ED LOS.A total of 149,472 patients was included for analysis with an overall medium ED LOS of 2.15 [interquartile range (IQR) = 6.51] hours. The medium LOS for discharged, admission, and mortality patients was 1.46 (IQR = 2.07), 11.3 (IQR = 33.2), and 7.53 (IQR = 28.0) hours, respectively. In multivariate analysis, age (TR = 1.012, P < 0.0001], higher acuity (triage level I vs level V, TR = 2.371, P < 0.0001), pediatric nontrauma (compared with adult nontrauma, TR = 3.084, P < 0.0001), transferred patients (TR = 2.712, P < 0.0001), and day shift arrival (compared with night shift, TR = 1.451, P < 0.0001) were associated with prolonged ED LOS in the discharged patient group. However, opposite results were noted for higher acuity (triage level I vs level V, TR = 0.532, P < 0.0001), pediatric nontrauma (TR = 0.375, P < 0.0001), transferred patients (TR = 0.852, P < 0.0001), and day shift arrival (TR = 0.88, P < 0.0001) in the admission patient group.Common influential factors such as age, patient entity, triage acuity level, or arrival time may have varying effects on different disposition groups of patients. These findings and the suggested model could be used for EDs to develop individually tailored approaches to minimize ED LOS and further improve ED crowding status

  16. Competing risks of death in women treated with adjuvant aromatase inhibitors for early breast cancer on NCIC CTG MA.27.

    PubMed

    Chapman, Judith-Anne W; Shepherd, Lois E; Ingle, James N; Muss, Hyman B; Pritchard, Kathleen I; Gelmon, Karen A; Whelan, Timothy J; Elliott, Catherine; Goss, Paul E

    2016-04-01

    Baseline patient and tumor characteristics differentially affected type of death in the MA.17 placebo-controlled letrozole trial where cardiovascular death was not separately identified. The MA.27 trial allowed competing risks analysis of breast cancer (BC), cardiovascular, and other type (OT) of death. MA.27 was a phase III adjuvant breast cancer trial of exemestane versus anastrozole. Effects of baseline patient and tumor characteristics were tested for whether factors were associated with (1) all cause mortality and (2) cause-specific mortality. We also fit step-wise forward cause-specific-adjusted models. 7576 women (median age 64 years; 5417 (72 %) < 70 years and 2159 (28 %) ≥ 70 years) were enrolled and followed for median 4.1 years. The 432 deaths comprised 187 (43 %) BC, 66 (15 %) cardiovascular, and 179 (41 %) OT. Five baseline factors were differentially associated with type of death. Older patients had greater BC (p = 0.03), cardiovascular (p < 0.001), and other types (p < 0.001) of mortality. Patients with pre-existing cardiovascular history had worse cardiovascular mortality (p < 0.001); those with worse ECOG performance status had worse OT mortality (p < 0.001). Patients with T1 tumors (p < 0.001) and progesterone receptor positive had less BC mortality (p < 0.001). Fewer BC deaths occurred with node-negative disease (p < 0.001), estrogen receptor-positive tumors (p = 0.001), and without adjuvant chemotherapy (p = 0.005); worse cardiovascular mortality (p = 0.01), with trastuzumab; worse OT mortality, for non-whites (p = 0.03) and without adjuvant radiotherapy (p = 0.003). Overall, 57 % of deaths in MA.27 AI-treated patients were non-breast cancer related. Baseline patient and tumor characteristics differentially affected type of death with women 70 or older experiencing more non-breast cancer death. PMID:27006189

  17. Analyzing Factors Affecting Emergency Department Length of Stay—Using a Competing Risk-accelerated Failure Time Model

    PubMed Central

    Chaou, Chung-Hsien; Chiu, Te-Fa; Yen, Amy Ming-Fang; Ng, Chip-Jin; Chen, Hsiu-Hsi

    2016-01-01

    Abstract Emergency department (ED) length of stay (LOS) is associated with ED crowding and related complications. Previous studies either analyzed single patient disposition groups or combined different endpoints as a whole. The aim of this study is to evaluate different effects of relevant factors affecting ED LOS among different patient disposition groups. This is a retrospective electronic data analysis. The ED LOS and relevant covariates of all patients between January 2013 and December 2013 were collected. A competing risk accelerated failure time model was used to compute endpoint type-specific time ratios (TRs) for ED LOS. A total of 149,472 patients was included for analysis with an overall medium ED LOS of 2.15 [interquartile range (IQR) = 6.51] hours. The medium LOS for discharged, admission, and mortality patients was 1.46 (IQR = 2.07), 11.3 (IQR = 33.2), and 7.53 (IQR = 28.0) hours, respectively. In multivariate analysis, age (TR = 1.012, P < 0.0001], higher acuity (triage level I vs level V, TR = 2.371, P < 0.0001), pediatric nontrauma (compared with adult nontrauma, TR = 3.084, P < 0.0001), transferred patients (TR = 2.712, P < 0.0001), and day shift arrival (compared with night shift, TR = 1.451, P < 0.0001) were associated with prolonged ED LOS in the discharged patient group. However, opposite results were noted for higher acuity (triage level I vs level V, TR = 0.532, P < 0.0001), pediatric nontrauma (TR = 0.375, P < 0.0001), transferred patients (TR = 0.852, P < 0.0001), and day shift arrival (TR = 0.88, P < 0.0001) in the admission patient group. Common influential factors such as age, patient entity, triage acuity level, or arrival time may have varying effects on different disposition groups of patients. These findings and the suggested model could be used for EDs to develop individually tailored approaches to minimize ED LOS and further improve ED crowding

  18. Competent psychopharmacology.

    PubMed

    Gardner, David M

    2014-08-01

    There is little doubt that undergraduate and post-graduate training of physicians, pharmacists, and nurses is insufficient to prepare them to use psychotropics safely and effectively, especially in the context of their expanded off-label uses. Therefore, the development of competencies in psychotropic prescribing needs to be approached as a long-term, practice-based learning commitment. Proposed are the abilities and knowledge components necessary for safe and effective use of psychotropics. Typical challenges in prescribing for chronic and recurrent illnesses include highly variable responses and tolerability, drug interactions, and adverse effects that can be serious, irreversible, and even fatal. Prescribing psychotropics is further complicated by negative public and professional reports and growing patient concerns about the quality of care, and questions about the efficacy, safety, and addictive risks of psychotropics. Increased efforts are needed to enhance clinical training and knowledge in psychopharmacology among trainees and practising clinicians, with more comprehensive and sustained attention to the assessment of individual patients, and greater reliance on patient education and collaboration. Improved competence in psychotropic prescribing should lead to more informed, thoughtful, and better-targeted applications as one component of more comprehensive clinical care. PMID:25161064

  19. Competent Psychopharmacology

    PubMed Central

    Gardner, David M

    2014-01-01

    There is little doubt that undergraduate and post-graduate training of physicians, pharmacists, and nurses is insufficient to prepare them to use psychotropics safely and effectively, especially in the context of their expanded off-label uses. Therefore, the development of competencies in psychotropic prescribing needs to be approached as a long-term, practice-based learning commitment. Proposed are the abilities and knowledge components necessary for safe and effective use of psychotropics. Typical challenges in prescribing for chronic and recurrent illnesses include highly variable responses and tolerability, drug interactions, and adverse effects that can be serious, irreversible, and even fatal. Prescribing psychotropics is further complicated by negative public and professional reports and growing patient concerns about the quality of care, and questions about the efficacy, safety, and addictive risks of psychotropics. Increased efforts are needed to enhance clinical training and knowledge in psychopharmacology among trainees and practising clinicians, with more comprehensive and sustained attention to the assessment of individual patients, and greater reliance on patient education and collaboration. Improved competence in psychotropic prescribing should lead to more informed, thoughtful, and better-targeted applications as one component of more comprehensive clinical care. PMID:25161064

  20. Competing risks and the development of adaptive management plans for water resources: Field reconnaissance investigation of risks to fishes and other aquatic biota exposed to endocrine disrupting chemicals (edcs) in lake mead, Nevada USA

    USGS Publications Warehouse

    Linder, G.; Little, E.E.

    2009-01-01

    The analysis and characterization of competing risks for water resources rely on a wide spectrum of tools to evaluate hazards and risks associated with their management. For example, waters of the lower Colorado River stored in reservoirs such as Lake Mead present a wide range of competing risks related to water quantity and water quality. These risks are often interdependent and complicated by competing uses of source waters for sustaining biological resources and for supporting a range of agricultural, municipal, recreational, and industrial uses. USGS is currently conducting a series of interdisciplinary case-studies on water quality of Lake Mead and its source waters. In this case-study we examine selected constituents potentially entering the Lake Mead system, particularly endocrine disrupting chemicals (EDCs). Worldwide, a number of environmental EDCs have been identified that affect reproduction, development, and adaptive behaviors in a wide range of organisms. Many EDCs are minimally affected by current treatment technologies and occur in treated sewage effluents. Several EDCs have been detected in Lake Mead, and several substances have been identified that are of concern because of potential impacts to the aquatic biota, including the sport fishery of Lake Mead and endangered razorback suckers (Xyrauchen texanus) that occur in the Colorado River system. For example, altered biomarkers relevant to reproduction and thyroid function in fishes have been observed and may be predictive of impaired metabolism and development. Few studies, however, have addressed whether such EDC-induced responses observed in the field have an ecologically significant effect on the reproductive success of fishes. To identify potential linkages between EDCs and species of management concern, the risk analysis and characterization in this reconnaissance study focused on effects (and attendant uncertainties) that might be expressed by exposed populations. In addition, risk reduction

  1. Professional Development for ECEC Practitioners with Responsibilities for Children at Risk: Which Competences and In-Service Training Are Needed?

    ERIC Educational Resources Information Center

    Peeters, Jan; Sharmahd, Nima

    2014-01-01

    There is growing evidence among researchers and international organisations that quality of Early Childhood Education and Care (ECEC), and ultimately the outcomes for children and families--especially disadvantaged ones--is dependent on well-educated and competent staff, and that a lack of higher pre-service training can be partly compensated by…

  2. Linking the Prevention of Problem Behaviors and Positive Youth Development: Core Competencies for Positive Youth Development and Risk Prevention

    ERIC Educational Resources Information Center

    Guerra, Nancy G.; Bradshaw, Catherine P.

    2008-01-01

    In this chapter, we present a brief review of the developmental literature linking healthy adjustment to five core competencies: (1) positive sense of self, (2) self-control, (3) decision-making skills, (4) a moral system of belief, and (5) prosocial connectedness. A central premise of this chapter and the rest of the volume is that promoting…

  3. Sex Offender Situational Competency Test (SOSCT) Pretreatment and Posttreatment Effects for Inpatient Sex Offenders in Hypothetical High-Risk Situations

    ERIC Educational Resources Information Center

    Reddon, John R.; Takacs, Shelly; Hogan, Stephen

    2013-01-01

    The purpose of the study was to evaluate relapse prevention skill acquisition within the context of a comprehensive treatment program involving group psychotherapy, relapse prevention programming, and other essential psychoeducational components. The Sex Offender Situational Competency Test (SOSCT) was administered pretreatment and posttreatment…

  4. Patients' Competence in and Performance of Cognitive Therapy Skills: Relation to the Reduction of Relapse Risk Following Treatment for Depression

    ERIC Educational Resources Information Center

    Strunk, Daniel R.; DeRubeis, Robert J.; Chiu, Angela W.; Alvarez, Jennifer

    2007-01-01

    Cognitive therapy (CT) for depression is designed to teach patients material that is believed to help prevent relapse following successful treatment. This study of 35 moderately to severely depressed patients who responded to CT provides the 1st evidence to suggest that both development and independent use of these competencies predict reduced…

  5. Competing Uses of Underground Systems Related to Energy Supply: Applying Single- and Multiphase Simulations for Site Characterization and Risk-Analysis

    NASA Astrophysics Data System (ADS)

    Kissinger, A.; Walter, L.; Darcis, M.; Flemisch, B.; Class, H.

    2012-04-01

    Global climate change, shortage of resources and the resulting turn towards renewable sources of energy lead to a growing demand for the utilization of subsurface systems. Among these competing uses are Carbon Capture and Storage (CCS), geothermal energy, nuclear waste disposal, "renewable" methane or hydrogen storage as well as the ongoing production of fossil resources like oil, gas, and coal. Besides competing among themselves, these technologies may also create conflicts with essential public interests like water supply. For example, the injection of CO2 into the underground causes an increase in pressure reaching far beyond the actual radius of influence of the CO2 plume, potentially leading to large amounts of displaced salt water. Finding suitable sites is a demanding task for several reasons. Natural systems as opposed to technical systems are always characterized by heterogeneity. Therefore, parameter uncertainty impedes reliable predictions towards capacity and safety of a site. State of the art numerical simulations combined with stochastic approaches need to be used to obtain a more reliable assessment of the involved risks and the radii of influence of the different processes. These simulations may include the modeling of single- and multiphase non-isothermal flow, geo-chemical and geo-mechanical processes in order to describe all relevant physical processes adequately. Stochastic approaches have the aim to estimate a bandwidth of the key output parameters based on uncertain input parameters. Risks for these different underground uses can then be made comparable with each other. Along with the importance and the urgency of the competing processes this may lead to a more profound basis for a decision. Communicating risks to stake holders and a concerned public is crucial for the success of finding a suitable site for CCS (or other subsurface utilization). We present and discuss first steps towards an approach for addressing the issue of competitive

  6. On the Importance of Accounting for Competing Risks in Pediatric Brain Cancer: II. Regression Modeling and Sample Size

    SciTech Connect

    Tai, Bee-Choo; Grundy, Richard; Machin, David

    2011-03-15

    Purpose: To accurately model the cumulative need for radiotherapy in trials designed to delay or avoid irradiation among children with malignant brain tumor, it is crucial to account for competing events and evaluate how each contributes to the timing of irradiation. An appropriate choice of statistical model is also important for adequate determination of sample size. Methods and Materials: We describe the statistical modeling of competing events (A, radiotherapy after progression; B, no radiotherapy after progression; and C, elective radiotherapy) using proportional cause-specific and subdistribution hazard functions. The procedures of sample size estimation based on each method are outlined. These are illustrated by use of data comparing children with ependymoma and other malignant brain tumors. The results from these two approaches are compared. Results: The cause-specific hazard analysis showed a reduction in hazards among infants with ependymoma for all event types, including Event A (adjusted cause-specific hazard ratio, 0.76; 95% confidence interval, 0.45-1.28). Conversely, the subdistribution hazard analysis suggested an increase in hazard for Event A (adjusted subdistribution hazard ratio, 1.35; 95% confidence interval, 0.80-2.30), but the reduction in hazards for Events B and C remained. Analysis based on subdistribution hazard requires a larger sample size than the cause-specific hazard approach. Conclusions: Notable differences in effect estimates and anticipated sample size were observed between methods when the main event showed a beneficial effect whereas the competing events showed an adverse effect on the cumulative incidence. The subdistribution hazard is the most appropriate for modeling treatment when its effects on both the main and competing events are of interest.

  7. Quantifying and comparing dynamic predictive accuracy of joint models for longitudinal marker and time-to-event in presence of censoring and competing risks.

    PubMed

    Blanche, Paul; Proust-Lima, Cécile; Loubère, Lucie; Berr, Claudine; Dartigues, Jean-François; Jacqmin-Gadda, Hélène

    2015-03-01

    Thanks to the growing interest in personalized medicine, joint modeling of longitudinal marker and time-to-event data has recently started to be used to derive dynamic individual risk predictions. Individual predictions are called dynamic because they are updated when information on the subject's health profile grows with time. We focus in this work on statistical methods for quantifying and comparing dynamic predictive accuracy of this kind of prognostic models, accounting for right censoring and possibly competing events. Dynamic area under the ROC curve (AUC) and Brier Score (BS) are used to quantify predictive accuracy. Nonparametric inverse probability of censoring weighting is used to estimate dynamic curves of AUC and BS as functions of the time at which predictions are made. Asymptotic results are established and both pointwise confidence intervals and simultaneous confidence bands are derived. Tests are also proposed to compare the dynamic prediction accuracy curves of two prognostic models. The finite sample behavior of the inference procedures is assessed via simulations. We apply the proposed methodology to compare various prediction models using repeated measures of two psychometric tests to predict dementia in the elderly, accounting for the competing risk of death. Models are estimated on the French Paquid cohort and predictive accuracies are evaluated and compared on the French Three-City cohort. PMID:25311240

  8. Joint modeling of longitudinal ordinal data and competing risks survival times and analysis of the NINDS rt-PA stroke trial

    PubMed Central

    Li, Ning; Elashoff, Robert M.; Li, Gang; Saver, Jeffrey

    2009-01-01

    SUMMARY Existing joint models for longitudinal and survival data are not applicable for longitudinal ordinal outcomes with possible non-ignorable missing values caused by multiple reasons. We propose a joint model for longitudinal ordinal measurements and competing risks failure time data, in which a partial proportional odds model for the longitudinal ordinal outcome is linked to the event times by latent random variables. At the survival endpoint, our model adopts the competing risks framework to model multiple failure types at the same time. The partial proportional odds model, as an extension of the popular proportional odds model for ordinal outcomes, is more flexible and at the same time provides a tool to test the proportional odds assumption. We use a likelihood approach and derive an EM algorithm to obtain the maximum likelihood estimates of the parameters. We further show that all the parameters at the survival endpoint are identifiable from the data. Our joint model enables one to make inference for both the longitudinal ordinal outcome and the failure times simultaneously. In addition, the inference at the longitudinal endpoint is adjusted for possible non-ignorable missing data caused by the failure times. We apply the method to the NINDS rt-PA stroke trial. Our study considers the modified Rankin Scale only. Other ordinal outcomes in the trial, such as the Barthel and Glasgow scales can be treated in the same way. PMID:19943331

  9. Predictors of all-cause and cardiovascular-specific mortality in type 2 diabetes: A competing risk modeling of an Iranian population

    PubMed Central

    Sadeghpour, Sahar; Faghihimani, Elham; Hassanzadeh, Akbar; Amini, Masoud; Mansourian, Marjan

    2016-01-01

    Background: In Asian population, diabetes mellitus is increasing and has become an important health problem in recent decades. In Iran, cardiovascular disease (CVD) accounts for nearly 46% of the total costs spent for diabetes-associated diseases. Because individuals with diabetes have highly increased CVD risk compared with normal individuals, it is important to diagnosis factors that may increase CVD risk in diabetic patients. The study objective was to identify predictors associated with CVD mortality in patients with type 2 diabetes (T2D) and to develop a prediction model for cardiovascular (CV)-death using a competing risk approach. Materials and Methods: The study population consisted of 2638 T2D (male = 1110, female = 1528) patients aged ≥35 years attending from Endocrine and Metabolism Research Center in Isfahan for a mean follow-up period of 12 years; predictors for different cause of death were evaluated using cause specific Cox proportional and subdistribution hazards models. Results: Based on competing modeling, the increase in blood pressure (BP) (spontaneously hypertensive rats [SHR]: 1.64), cholesterol (SHR: 1.55), and duration of diabetes (SHR: 2.03) were associated with CVD-death. Also, the increase in BP (SHR: 1.85), fasting blood sugar (SHR: 2.94), and duration of diabetes (SHR: 1.68) were associated with other death (consist of cerebrovascular accidents, cancer, infection, and diabetic nephropathy). Conclusions: This finding suggests that more attention should be paid to the management of CV risk in type 2 diabetic patients with high cholesterol, high BP, and long diabetes duration. PMID:27274497

  10. Parametric Rietveld refinement

    PubMed Central

    Stinton, Graham W.; Evans, John S. O.

    2007-01-01

    In this paper the method of parametric Rietveld refinement is described, in which an ensemble of diffraction data collected as a function of time, temperature, pressure or any other variable are fitted to a single evolving structural model. Parametric refinement offers a number of potential benefits over independent or sequential analysis. It can lead to higher precision of refined parameters, offers the possibility of applying physically realistic models during data analysis, allows the refinement of ‘non-crystallographic’ quantities such as temperature or rate constants directly from diffraction data, and can help avoid false minima. PMID:19461841

  11. DWPF welder parametric study

    SciTech Connect

    Eberhard, B.J.; Harbour, J.R.; Plodinec, M.J.

    1994-06-01

    As part of the DWPF Startup Test Program, a parametric study has been performed to determine a range of welder operating parameters which will produce acceptable final welds for canistered waste forms. The parametric window of acceptable welds defined by this study is 90,000 {plus_minus} 15,000 lb of force, 248,000 {plus_minus} 22,000 amps of current, and 95 {plus_minus} 15 cycles (@ 60 cops) for the time of application of the current.

  12. DWPF Welder Parametric Study

    SciTech Connect

    Plodinec, M.J.

    1998-11-20

    After being filled with glass, DWPF canistered waste forms will be welded closed using an upset resistance welding process. This final closure weld must be leaktight, and must remain so during extended storage at SRS. As part of the DWPF Startup Test Program, a parametric study (DWPF-WP-24) has been performed to determine a range of welder operating parameters which will produce acceptable welds. The parametric window of acceptable welds defined by this study is 90,000 + 15,000 lb of force, 248,000 + 22,000 amps of current, and 95 + 15 cycles* for the time of application of the current.

  13. Elderly Peritoneal Dialysis Compared with Elderly Hemodialysis Patients and Younger Peritoneal Dialysis Patients: Competing Risk Analysis of a Korean Prospective Cohort Study

    PubMed Central

    Kim, Hyunsuk; An, Jung Nam; Kim, Dong Ki; Kim, Myoung-Hee; Kim, Ho; Kim, Yong-Lim; Park, Ki Soo; Oh, Yun Kyu; Lim, Chun Soo; Kim, Yon Su; Lee, Jung Pyo

    2015-01-01

    The outcomes of peritoneal dialysis (PD) in elderly patients have not been thoroughly investigated. We aimed to investigate the clinical outcomes and risk factors associated with PD in elderly patients. We conducted a prospective observational nationwide adult end-stage renal disease (ESRD) cohort study in Korea from August 2008 to March 2013. Among incident patients (n = 830), patient and technical survival rate, quality of life, and Beck’s Depression Inventory (BDI) scores of elderly PD patients (≥65 years, n = 95) were compared with those of PD patients aged ≤49 years (n = 205) and 50~64 years (n = 192); and elderly hemodialysis (HD) patients (n = 315). The patient death and technical failure were analyzed by cumulative incidence function. Competing risk regressions were used to assess the risk factors for survival. The patient survival rate of elderly PD patients was inferior to that of younger PD patients (P<0.001). However, the technical survival rate was similar (P = 0.097). Compared with elderly HD patients, the patient survival rate did not differ according to dialysis modality (P = 0.987). Elderly PD patients showed significant improvement in the BDI scores, as compared with the PD patients aged ≤49 years (P = 0.003). Low albumin, diabetes and low residual renal function were significant risk factors for the PD patient survival; and peritonitis was a significant risk factor for technical survival. Furthermore, low albumin and hospitalization were significant risk factors of patient survival among the elderly. The overall outcomes were similar between elderly PD and HD patients. PD showed the benefit in BDI and quality of life in the elderly. Additionally, the technical survival rate of elderly PD patients was similar to that of younger PD patients. Taken together, PD may be a comparable modality for elderly ESRD patients. PMID:26121574

  14. Elderly Peritoneal Dialysis Compared with Elderly Hemodialysis Patients and Younger Peritoneal Dialysis Patients: Competing Risk Analysis of a Korean Prospective Cohort Study.

    PubMed

    Kim, Hyunsuk; An, Jung Nam; Kim, Dong Ki; Kim, Myoung-Hee; Kim, Ho; Kim, Yong-Lim; Park, Ki Soo; Oh, Yun Kyu; Lim, Chun Soo; Kim, Yon Su; Lee, Jung Pyo

    2015-01-01

    The outcomes of peritoneal dialysis (PD) in elderly patients have not been thoroughly investigated. We aimed to investigate the clinical outcomes and risk factors associated with PD in elderly patients. We conducted a prospective observational nationwide adult end-stage renal disease (ESRD) cohort study in Korea from August 2008 to March 2013. Among incident patients (n = 830), patient and technical survival rate, quality of life, and Beck's Depression Inventory (BDI) scores of elderly PD patients (≥65 years, n = 95) were compared with those of PD patients aged ≤49 years (n = 205) and 50~64 years (n = 192); and elderly hemodialysis (HD) patients (n = 315). The patient death and technical failure were analyzed by cumulative incidence function. Competing risk regressions were used to assess the risk factors for survival. The patient survival rate of elderly PD patients was inferior to that of younger PD patients (P<0.001). However, the technical survival rate was similar (P = 0.097). Compared with elderly HD patients, the patient survival rate did not differ according to dialysis modality (P = 0.987). Elderly PD patients showed significant improvement in the BDI scores, as compared with the PD patients aged ≤49 years (P = 0.003). Low albumin, diabetes and low residual renal function were significant risk factors for the PD patient survival; and peritonitis was a significant risk factor for technical survival. Furthermore, low albumin and hospitalization were significant risk factors of patient survival among the elderly. The overall outcomes were similar between elderly PD and HD patients. PD showed the benefit in BDI and quality of life in the elderly. Additionally, the technical survival rate of elderly PD patients was similar to that of younger PD patients. Taken together, PD may be a comparable modality for elderly ESRD patients. PMID:26121574

  15. Parametric Differentiation and Integration

    ERIC Educational Resources Information Center

    Chen, Hongwei

    2009-01-01

    Parametric differentiation and integration under the integral sign constitutes a powerful technique for calculating integrals. However, this topic is generally not included in the undergraduate mathematics curriculum. In this note, we give a comprehensive review of this approach, and show how it can be systematically used to evaluate most of the…

  16. The influence of the perceived consequences of refusing to share injection equipment among injection drug users: Balancing competing risks

    PubMed Central

    Wagner, Karla D.; Lankenau, Stephen E.; Palinkas, Lawrence A.; Richardson, Jean L.; Chou, Chih-Ping; Unger, Jennifer B.

    2011-01-01

    Injection drug users (IDUs) are at risk for HIV and other bloodborne pathogens through receptive syringe sharing (RSS) and receptive paraphernalia sharing (RPS). Research into the influence of the perceived risk of HIV infection on injection risk behavior has yielded mixed findings. One explanation may be that consequences other than HIV infection are considered when IDUs are faced with decisions about whether or not to share equipment. We investigated the perceived consequences of refusing to share injection equipment among 187 IDUs recruited from a large syringe exchange program in Los Angeles, California, assessed their influence on RSS and RPS, and evaluated gender differences. Two sub-scales of perceived consequences were identified: structural/external consequences and social/internal consequences. In multiple linear regression, the perceived social/internal consequences of refusing to share were associated with both RSS and RPS, after controlling for other psychosocial constructs and demographic variables. Few statistically significant gender differences emerged. Assessing the consequences of refusing to share injection equipment may help explain persistent injection risk behavior, and may provide promising targets for comprehensive intervention efforts designed to address both individual and structural risk factors. PMID:21498004

  17. Setting priorities for private land conservation in fire-prone landscapes: Are fire risk reduction and biodiversity conservation competing or compatible objectives?

    USGS Publications Warehouse

    Syphard, Alexandra D.; Butsic, Van; Bar-Massada, Avi; Keeley, Jon E.; Tracey, Jeff A.; Fisher, Robert N.

    2016-01-01

    Although wildfire plays an important role in maintaining biodiversity in many ecosystems, fire management to protect human assets is often carried out by different agencies than those tasked for conserving biodiversity. In fact, fire risk reduction and biodiversity conservation are often viewed as competing objectives. Here we explored the role of management through private land conservation and asked whether we could identify private land acquisition strategies that fulfill the mutual objectives of biodiversity conservation and fire risk reduction, or whether the maximization of one objective comes at a detriment to the other. Using a fixed budget and number of homes slated for development, we simulated 20 years of housing growth under alternative conservation selection strategies, and then projected the mean risk of fires destroying structures and the area and configuration of important habitat types in San Diego County, California, USA. We found clear differences in both fire risk projections and biodiversity impacts based on the way conservation lands are prioritized for selection, but these differences were split between two distinct groupings. If no conservation lands were purchased, or if purchases were prioritized based on cost or likelihood of development, both the projected fire risk and biodiversity impacts were much higher than if conservation lands were purchased in areas with high fire hazard or high species richness. Thus, conserving land focused on either of the two objectives resulted in nearly equivalent mutual benefits for both. These benefits not only resulted from preventing development in sensitive areas, but they were also due to the different housing patterns and arrangements that occurred as development was displaced from those areas. Although biodiversity conflicts may still arise using other fire management strategies, this study shows that mutual objectives can be attained through land-use planning in this region. These results likely

  18. A semi-parametric approach to estimate risk functions associated with multi-dimensional exposure profiles: application to smoking and lung cancer

    PubMed Central

    2013-01-01

    Background A common characteristic of environmental epidemiology is the multi-dimensional aspect of exposure patterns, frequently reduced to a cumulative exposure for simplicity of analysis. By adopting a flexible Bayesian clustering approach, we explore the risk function linking exposure history to disease. This approach is applied here to study the relationship between different smoking characteristics and lung cancer in the framework of a population based case control study. Methods Our study includes 4658 males (1995 cases, 2663 controls) with full smoking history (intensity, duration, time since cessation, pack-years) from the ICARE multi-centre study conducted from 2001-2007. We extend Bayesian clustering techniques to explore predictive risk surfaces for covariate profiles of interest. Results We were able to partition the population into 12 clusters with different smoking profiles and lung cancer risk. Our results confirm that when compared to intensity, duration is the predominant driver of risk. On the other hand, using pack-years of cigarette smoking as a single summary leads to a considerable loss of information. Conclusions Our method estimates a disease risk associated to a specific exposure profile by robustly accounting for the different dimensions of exposure and will be helpful in general to give further insight into the effect of exposures that are accumulated through different time patterns. PMID:24152389

  19. Parametric Explosion Spectral Model

    SciTech Connect

    Ford, S R; Walter, W R

    2012-01-19

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

  20. Glycated Hemoglobin Level and Risk of Hip Fracture in Older People with Type 2 Diabetes: A Competing Risk Analysis of Taiwan Diabetes Cohort Study.

    PubMed

    Li, Chia-Ing; Liu, Chiu-Shong; Lin, Wen-Yuan; Meng, Nai-Hsin; Chen, Ching-Chu; Yang, Sing-Yu; Chen, Hsuan-Ju; Lin, Cheng-Chieh; Li, Tsai-Chung

    2015-07-01

    Hip fracture, which is associated with substantial morbidity and long-term mortality, imposes a major burden on the healthcare system. Diabetes is a risk factor for osteoporosis, which is a crucial risk factor of hip fracture. However, epidemiological studies investigating the risk of hip fracture among patients with type 2 diabetes are limited. This study explored the association between hemoglobin A1c (HbA1c) and the risk of hip fracture in people with type 2 diabetes aged 65 years and older. We conducted a retrospective cohort study of 20,025 older patients with type 2 diabetes who participated in the National Diabetes Case Management Program in Taiwan. The HbA1c level at the baseline and hip fracture incidence over an average of 7.41 years of follow-up were analyzed (maximum and standard deviation were 10.9 and 2.42 years, respectively). A total of 1514 hip fracture cases were recorded. The incidence rates of hip fracture were 9.15, 8.02, 9.58, 10.61, 12.51, and 13.43 per 1000 person-years in patients with baseline HbA1c levels of < 6%, 6-7%, 7%-8%, 8%-9%, 9%-10%, and ≥ 10%, respectively. After multivariate adjustment, the risk of hip fracture increased among patients with HbA1c levels of 9%-10% and ≥ 10.0% compared with patients with HbA1c levels of 6-7% (hazard ratio, 1.24; 95% confidence interval, 1.02-1.49 and 1.32; 1.09-1.58, respectively). Significant linear trends among various HbA1c levels were observed (P  < 0.05). Patients with type 2 diabetes whose HbA1c levels exceeded 9.0% exhibited an increased risk of hip fracture, confirming a linear relationship. Our study's findings demonstrated the importance of glycemic control for fracture prevention in older adults with type 2 diabetes. PMID:25598134

  1. Theme: Coping with Competencies.

    ERIC Educational Resources Information Center

    Brown, Daniel; And Others

    1989-01-01

    Consists of five articles on the topic of competencies in vocational agriculture. Topics covered include (1) competency-based instruction, (2) competencies for agricultural recordkeeping, (3) competencies in hydroponics, and (4) competencies in agribusiness. (CH)

  2. Parametric approaches to quality-adjusted survival analysis. International Breast Cancer Study Group.

    PubMed

    Cole, B F; Gelber, R D; Anderson, K M

    1994-09-01

    We present a parametric methodology for performing quality-of-life-adjusted survival analysis using multivariate censored survival data. It represents a generalization of the nonparametric Q-TWiST method (Quality-adjusted Time without Symptoms and Toxicity). The event times correspond to transitions between states of health that differ in terms of quality of life. Each transition is governed by a competing risks model where the health states are the competing risks. Overall survival is the sum of the amount of time spent in each health state. The first step of the proposed methodology consists of defining a quality function that assigns a "score" to a life having given health state transitions. It is a composite measure of both quantity and quality of life. In general, the quality function assigns a small value to a short life with poor quality and a high value to a long life with good quality. In the second step, parametric survival models are fit to the data. This is done by repeatedly modeling the conditional cause-specific hazard functions given the previous transitions. Covariates are incorporated by accelerated failure time regression, and the model parameters are estimated by maximum likelihood. Lastly, the modeling results are used to estimate the expectation of quality functions. Standard errors and confidence intervals are computed using the bootstrap and delta methods. The results are useful for simultaneously evaluating treatments in terms of quantity and quality of life. To demonstrate the proposed methods, we perform an analysis of data from the International Breast Cancer Study Group Trial V, which compared short-duration chemotherapy versus long-duration chemotherapy in the treatment of node-positive breast cancer. The events studied are: (1) the end of treatment toxicity, (2) disease recurrence, and (3) overall survival. PMID:7981389

  3. Relationship influences on teachers’ perceptions of academic competence in academically at-risk minority and majority first grade students

    PubMed Central

    Hughes, Jan N.; Gleason, Katie A.; Zhang, Duan

    2010-01-01

    This study examined the associations among child demographic variables, teacher perceptions of parent–teacher and student–teacher relationship quality, and teacher perceptions of children’s academic abilities in an ethnically diverse sample of 607 academically at-risk first grade children. Relative to relationships with African American children and parents, teachers rated their relationships with White and Hispanic children and parents more positively. Measures of relationship quality added unique variance to teachers’ perceptions of children’s abilities, controlling for parent educational level and measured ability. Relationship variables fully mediated the association between African American status and teachers’ perceptions of children’s abilities. Implications of the findings for teacher in-service and professional development and for parent involvement programs are discussed. PMID:20401185

  4. Topological transition of the parametric expression site of tumor suppressor inactivation as a marker evidence of environmental hormone-oriented cancer risk increase.

    PubMed

    Kodama, M; Murakami, M; Kodama, T

    1999-08-01

    The present study is an extension of our recent study in which we attempted statistical analysis of the data assembly of age-adjusted incidence rates (AAIRs) of a tumor without topological data manipulation for each of 20 individual tumors in scope, for each of 6 cancer registration areas in space, and for a period of early 1960's to mid 1980's in time. This time, a data assembly of log AAIR changes in time and space first passed through the process of topological data manipulation, and then underwent the sequential regression analysis so that we could assess the fitness of log AAIR changes either in space or in time to the equilibrium model of the law of mass action from the viewpoint of the interaction between oncogene activation and tumor suppressor gene inactivation. For the sake of comparison, the fitness of the cancer risk data to the equilibrium model was assessed in the framework of 3 sets of coordinates: a) the original (x org, y org) coordinates in which most of the log AAIR data assemblies in their data variations were classified as the oncogene activation type in the field of centripetal force (r seq=-1.000). b) The rect (X rect, Y rect) coordinates in which the log AAIR data assemblies were very often classified as the tumor suppressor gene inactivation type in the field of centrifugal force (r seq=+1.000). c) The para (X para, Y para) coordinates in which the log AAIR data assemblies were mostly classified as the intermediate type as regards the fitness to the equilibrium model. The rect-coordinates and the para-coordinates, 2 variants of angular rotation of the original coordinates, were so designed as to allow their X-axes to run each at a right angle and parallel to the regression line of the original pair data block. The results obtained were as follows: a) poor fitness of the log AAIR changes in space to the equilibrium model in the rect-coordinates was found in male breast cancer, male thyroid cancer, female esophageal cancer, female laryngeal

  5. Parametric Hazard Function Estimation.

    Energy Science and Technology Software Center (ESTSC)

    1999-09-13

    Version 00 Phaze performs statistical inference calculations on a hazard function (also called a failure rate or intensity function) based on reported failure times of components that are repaired and restored to service. Three parametric models are allowed: the exponential, linear, and Weibull hazard models. The inference includes estimation (maximum likelihood estimators and confidence regions) of the parameters and of the hazard function itself, testing of hypotheses such as increasing failure rate, and checking ofmore » the model assumptions.« less

  6. Multipass optical parametric amplifier

    SciTech Connect

    Jeys, T.H.

    1996-08-01

    A compact, low-threshold, multipass optical parametric amplifier has been developed for the conversion of short-pulse (360-ps) 1064-nm Nd:YAG laser radiation into eye-safe 1572-nm radiation for laser ranging and radar applications. The amplifier had a threshold pump power of as low as 45{mu}J, and at three to four times this threshold pump power the amplifier converted 30{percent} of the input 1064-nm radiation into 1572-nm output radiation. {copyright} {ital 1996 Optical Society of America.}

  7. Parametric Trace Slicing

    NASA Technical Reports Server (NTRS)

    Rosu, Grigore (Inventor); Chen, Feng (Inventor); Chen, Guo-fang; Wu, Yamei; Meredith, Patrick O. (Inventor)

    2014-01-01

    A program trace is obtained and events of the program trace are traversed. For each event identified in traversing the program trace, a trace slice of which the identified event is a part is identified based on the parameter instance of the identified event. For each trace slice of which the identified event is a part, the identified event is added to an end of a record of the trace slice. These parametric trace slices can be used in a variety of different manners, such as for monitoring, mining, and predicting.

  8. Dynamic Assessment of Seismic Risk (DASR) by Multi-parametric Observations: Preliminary Results of PRIME experiment within the PRE-EARTHQUAKES EU-FP7 Project

    NASA Astrophysics Data System (ADS)

    Tramutoli, V.; Inan, S.; Jakowski, N.; Pulinets, S. A.; Romanov, A.; Filizzola, C.; Shagimuratov, I.; Pergola, N.; Ouzounov, D. P.; Papadopoulos, G. A.; Parrot, M.; Genzano, N.; Lisi, M.; Alparlsan, E.; Wilken, V.; Tsybukia, K.; Romanov, A.; Paciello, R.; Zakharenkova, I.; Romano, G.

    2012-12-01

    The integration of different observations together with the refinement of data analysis methods, is generally expected to improve our present knowledge of preparatory phases of earthquakes and of their possible precursors. This is also the main goal of PRE-EARTHQUAKES (Processing Russian and European EARTH observations for earthQUAKE precursors Studies) the FP7 Project which, to this aim, committed together, different international expertise and observational capabilities, in the last 2 years. In the learning phase of the project, different parameters (e.g. thermal anomalies, total electron content, radon concentration, etc.), measured from ground and satellite systems and analyzed by using different data analysis approaches, have been studied for selected geographic areas and specific seismic events in the past. Since July 2012 the PRIME (PRE-EARTHQUAKES Real-time Integration and Monitoring Experiment) started attempting to perform, on the base of independent observations collected and integrated in real-time through the PEG (PRE-EARTHQUAKES Geo-portal), a Dynamic Assessment of Seismic Risk (DASR) on selected geographic areas of Europe (Italy-Greece-Turkey) and Asia (Kamchatka, Sakhalin, Japan). In this paper, results so far achieved as well as the potential and opportunities they open for a worldwide Earthquake Observation System (EQuOS) - as a dedicated component of GEOSS (Global Earth Observation System of Systems) - will be presented.

  9. Progress in optical parametric oscillators

    NASA Technical Reports Server (NTRS)

    Fan, Y. X.; Byer, R. L.

    1984-01-01

    It is pointed out that tunable coherent sources are very useful for many applications, including spectroscopy, chemistry, combustion diagnostics, and remote sensing. Compared with other tunable sources, optical parametric oscillators (OPO) offer the potential advantage of a wide wavelength operating range, which extends from 0.2 micron to 25 microns. The current status of OPO is examined, taking into account mainly advances made during the last decade. Attention is given to early LiNbO3 parametric oscillators, problems which have prevented wide use of parametric oscillators, the demonstration of OPO's using urea and AgGaS2, progress related to picosecond OPO's, a breakthrough in nanosecond parametric oscillators, the first demonstration of a waveguide and fiber parametric amplification and generation, the importance of chalcopyrite crystals, and theoretical work performed with the aim to understand the factors affecting the parametric oscillator performance.

  10. HDAC1 and HDAC2 independently predict mortality in hepatocellular carcinoma by a competing risk regression model in a Southeast Asian population

    PubMed Central

    LER, SER YENG; LEUNG, CAROL HO WING; KHIN, LAY WAI; LU, GUO-DONG; SALTO-TELLEZ, MANUEL; HARTMAN, MIKAEL; IAU, PHILIP TSAU CHOONG; YAP, CELESTIAL T.; HOOI, SHING CHUAN

    2015-01-01

    Histone deacetylases (HDACs) are enzymes involved in transcriptional repression. We aimed to examine the significance of HDAC1 and HDAC2 gene expression in the prediction of recurrence and survival in 156 patients with hepatocellular carcinoma (HCC) among a South East Asian population who underwent curative surgical resection in Singapore. We found that HDAC1 and HDAC2 were upregulated in the majority of HCC tissues. The presence of HDAC1 in tumor tissues was correlated with poor tumor differentiation. Notably, HDAC1 expression in adjacent non-tumor hepatic tissues was correlated with the presence of satellite nodules and multiple lesions, suggesting that HDAC1 upregulation within the field of HCC may contribute to tumor spread. Using competing risk regression analysis, we found that increased cancer-specific mortality was significantly associated with HDAC2 expression. Mortality was also increased with high HDAC1 expression. In the liver cancer cell lines, HEP3B, HEPG2, PLC5, and a colorectal cancer cell line, HCT116, the combined knockdown of HDAC1 and HDAC2 increased cell death and reduced cell proliferation as well as colony formation. In contrast, knockdown of either HDAC1 or HDAC2 alone had minimal effects on cell death and proliferation. Taken together, our study suggests that both HDAC1 and HDAC2 exert pro-survival effects in HCC cells, and the combination of isoform-specific HDAC inhibitors against both HDACs may be effective in targeting HCC to reduce mortality. PMID:26352599

  11. Presuming Competence

    ERIC Educational Resources Information Center

    Biklen, Douglas; Burke, Jamie

    2006-01-01

    At least since the early 1990s, educators in inclusive schooling as well as scholars in Disability Studies have critiqued prevailing notions of intellectual ability and have suggested the importance of interpretive communities for constructing student competence (Biklen, 1990; Goode, 1992, 1994; Kliewer, 1998; Kluth, 2003; Linneman, 2001). This…

  12. Parametric energy converter

    SciTech Connect

    Johnson, R.N.

    1981-10-20

    A method and apparatus for converting thermal energy into mechanical energy by parametric pumping of rotary inertia. In a preferred embodiment, a modified tesla turbine rotor is positioned within a rotary boiler along its axis of rotation. An external heat source, such as solar radiation, is directed onto the outer casing of the boiler to convert the liquid to steam. As the steam spirals inwardly toward the discs of the rotor, the moment of inertia of the mass of steam is reduced to thereby substantially increase its kinetic energy. The laminar flow of steam between the discs of the rotor transfers the increased kinetic energy to the rotor which can be coupled out through an output shaft to perform mechanical work. A portion of the mechanical output can be fed back to maintain rotation of the boiler.

  13. Mechanical Parametric Oscillations and Waves

    ERIC Educational Resources Information Center

    Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.

    2013-01-01

    Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…

  14. Parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.

    1993-01-01

    Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.

  15. Extreme Levels of HbA1c Increase Incident ESRD Risk in Chinese Patients with Type 2 Diabetes: Competing Risk Analysis in National Cohort of Taiwan Diabetes Study

    PubMed Central

    Liu, Chiu-Shong; Huang, Chiu-Ching; Lin, Wen-Yuan; Chiang, Jen-Huai; Lin, Cheng-Chieh; Li, Tsai-Chung

    2015-01-01

    Background Whether HbA1c is a predictor of end-stage renal disease (ESRD) in type 2 diabetes patients remains unclear. This study evaluated relationship between HbA1c and ESRD in Chinese patients with type 2 diabetes. Methods Patients aged ≥ 30 years who were free of ESRD (n = 51 681) were included from National Diabetes Care Management Program from 2002–2003. Extended Cox proportional hazard model with competing risk of death served to evaluate association between HbA1c level and ESRD. Results A total of 2613 (5.06%) people developed ESRD during a follow-up period of 8.1 years. Overall incidence rate of ESRD was 6.26 per 1000 person-years. Patients with high levels of HbA1c had a high incidence rate of ESRD, from 4.29 for HbA1c of  6.0%–6.9% to 10.33 for HbA1c ≥ 10.0% per 1000 person-years. Patients with HbA1c < 6.0% particularly had a slightly higher ESRD incidence (4.34 per 1000 person-years) than those with HbA1c  of 6.0%–6.9%. A J-shaped relationship between HbA1c level and ESRD risk was observed. After adjustment, patients with HbA1c < 6.0% and ≥ 10.0% exhibited an increased risk of ESRD (HR: 1.99, 95% CI: 1.62–2.44; HR: 4.42, 95% CI: 3.80–5.14, respectively) compared with those with HbA1c of 6.0%–6.9%. Conclusions Diabetes care has focused on preventing hyperglycemia, but not hypoglycemia. Our study revealed that HbA1c level ≥ 7.0% was linked with increased ESRD risk in type 2 diabetes patients, and that HbA1c < 6.0% also had the potential to increase ESRD risk. Our study provides epidemiological evidence that appropriate glycemic control is essential for diabetes care to meet HbA1c targets and improve outcomes without increasing the risk to this population. Clinicians need to pay attention to HbA1c results on diabetic nephropathy. PMID:26098901

  16. Religious competence as cultural competence

    PubMed Central

    2012-01-01

    Definitions of cultural competence often refer to the need to be aware and attentive to the religious and spiritual needs and orientations of patients. However, the institution of psychiatry maintains an ambivalent attitude to the incorporation of religion and spirituality into psychiatric practice. This is despite the fact that many patients, especially those from underserved and underprivileged minority backgrounds, are devotedly religious and find much solace and support in their religiosity. I use the case of mental health of African Americans as an extended example to support the argument that psychiatric services must become more closely attuned to religious matters. I suggest ways in which this can be achieved. Attention to religion can aid in the development of culturally competent and accessible services, which in turn, may increase engagement and service satisfaction among religious populations. PMID:22421686

  17. Exploring deep parametric embeddings for breast CADx

    NASA Astrophysics Data System (ADS)

    Jamieson, Andrew R.; Alam, Rabi; Giger, Maryellen L.

    2011-03-01

    Computer-aided diagnosis (CADx) involves training supervised classifiers using labeled ("truth-known") data. Often, training data consists of high-dimensional feature vectors extracted from medical images. Unfortunately, very large data sets may be required to train robust classifiers for high-dimensional inputs. To mitigate the risk of classifier over-fitting, CADx schemes may employ feature selection or dimension reduction (DR), for example, principal component analysis (PCA). Recently, a number of novel "structure-preserving" DR methods have been proposed1. Such methods are attractive for use in CADx schemes for two main reasons. First, by providing visualization of highdimensional data structure, and second, since DR can be unsupervised or semi-supervised, unlabeled ("truth-unknown") data may be incorporated2. However, the practical application of state-of-the-art DR techniques such as, t-SNE3, to breast CADx were inhibited by the inability to retain a parametric embedding function capable of mapping new input data to the reduced representation. Deep (more than one hidden layer) neural networks can be used to learn such parametric DR embeddings. We explored the feasibility of such methods for use in CADx by conducting a variety of experiments using simulated feature data, including models based on breast CADx features. Specifically, we investigated the unsupervised parametric t-SNE4 (pt-SNE), the supervised deep t-distributed MCML5 (dt-MCML), and hybrid semi-supervised modifications combining the two.

  18. Parametric Mass Reliability Study

    NASA Technical Reports Server (NTRS)

    Holt, James P.

    2014-01-01

    The International Space Station (ISS) systems are designed based upon having redundant systems with replaceable orbital replacement units (ORUs). These ORUs are designed to be swapped out fairly quickly, but some are very large, and some are made up of many components. When an ORU fails, it is replaced on orbit with a spare; the failed unit is sometimes returned to Earth to be serviced and re-launched. Such a system is not feasible for a 500+ day long-duration mission beyond low Earth orbit. The components that make up these ORUs have mixed reliabilities. Components that make up the most mass-such as computer housings, pump casings, and the silicon board of PCBs-typically are the most reliable. Meanwhile components that tend to fail the earliest-such as seals or gaskets-typically have a small mass. To better understand the problem, my project is to create a parametric model that relates both the mass of ORUs to reliability, as well as the mass of ORU subcomponents to reliability.

  19. Parametric scramjet analysis

    NASA Astrophysics Data System (ADS)

    Choi, Jongseong

    The performance of a hypersonic flight vehicle will depend on existing materials and fuels; this work presents the performance of the ideal scramjet engine for three different combustion chamber materials and three different candidate fuels. Engine performance is explored by parametric cycle analysis for the ideal scramjet as a function of material maximum service temperature and the lower heating value of jet engine fuels. The thermodynamic analysis is based on the Brayton cycle as similarly employed in describing the performance of the ramjet, turbojet, and fanjet ideal engines. The objective of this work is to explore material operating temperatures and fuel possibilities for the combustion chamber of a scramjet propulsion system to show how they relate to scramjet performance and the seven scramjet engine parameters: specific thrust, fuel-to-air ratio, thrust-specific fuel consumption, thermal efficiency, propulsive efficiency, overall efficiency, and thrust flux. The information presented in this work has not been done by others in the scientific literature. This work yields simple algebraic equations for scramjet performance which are similar to that of the ideal ramjet, ideal turbojet and ideal turbofan engines.

  20. Parametric Equations, Maple, and Tubeplots.

    ERIC Educational Resources Information Center

    Feicht, Louis

    1997-01-01

    Presents an activity that establishes a graphical foundation for parametric equations by using a graphing output form called tubeplots from the computer program Maple. Provides a comprehensive review and exploration of many previously learned topics. (ASK)

  1. Population-based absolute risk estimation with survey data.

    PubMed

    Kovalchik, Stephanie A; Pfeiffer, Ruth M

    2014-04-01

    Absolute risk is the probability that a cause-specific event occurs in a given time interval in the presence of competing events. We present methods to estimate population-based absolute risk from a complex survey cohort that can accommodate multiple exposure-specific competing risks. The hazard function for each event type consists of an individualized relative risk multiplied by a baseline hazard function, which is modeled nonparametrically or parametrically with a piecewise exponential model. An influence method is used to derive a Taylor-linearized variance estimate for the absolute risk estimates. We introduce novel measures of the cause-specific influences that can guide modeling choices for the competing event components of the model. To illustrate our methodology, we build and validate cause-specific absolute risk models for cardiovascular and cancer deaths using data from the National Health and Nutrition Examination Survey. Our applications demonstrate the usefulness of survey-based risk prediction models for predicting health outcomes and quantifying the potential impact of disease prevention programs at the population level. PMID:23686614

  2. Incorporating parametric uncertainty into population viability analysis models

    USGS Publications Warehouse

    McGowan, Conor P.; Runge, Michael C.; Larson, Michael A.

    2011-01-01

    Uncertainty in parameter estimates from sampling variation or expert judgment can introduce substantial uncertainty into ecological predictions based on those estimates. However, in standard population viability analyses, one of the most widely used tools for managing plant, fish and wildlife populations, parametric uncertainty is often ignored in or discarded from model projections. We present a method for explicitly incorporating this source of uncertainty into population models to fully account for risk in management and decision contexts. Our method involves a two-step simulation process where parametric uncertainty is incorporated into the replication loop of the model and temporal variance is incorporated into the loop for time steps in the model. Using the piping plover, a federally threatened shorebird in the USA and Canada, as an example, we compare abundance projections and extinction probabilities from simulations that exclude and include parametric uncertainty. Although final abundance was very low for all sets of simulations, estimated extinction risk was much greater for the simulation that incorporated parametric uncertainty in the replication loop. Decisions about species conservation (e.g., listing, delisting, and jeopardy) might differ greatly depending on the treatment of parametric uncertainty in population models.

  3. Parametric design using IGRIP

    SciTech Connect

    Baker, C.

    1994-10-01

    The Department of Energy`s (DOE) Hanford site near Richland, Washington is being cleaned up after 50 years of nuclear materials production. One of the most serious problems at the site is the waste stored in single-shell underground storage tanks. There are 149 of these tanks containing the spent fuel residue remaining after the fuel is dissolved in acid and the desired materials (primarily plutonium and uranium) are separated out. The tanks are upright cylinders 75 ft. in diameter with domed tops. They are made of reinforced concrete, have steel liners, and each tank is buried under 7--12 ft. of overburden. The tanks are up to 40-ft. high, and have capacities of 500,000, 750,000, or 1,000,000 gallons of waste. As many as one-third of these tanks are known or suspected to leak. The waste form contained in the tanks varies in consistency from liquid supernatant to peanut-butter-like gels and sludges to hard salt cake (perhaps as hard as low-grade concrete). The current waste retrieval plan is to insert a large long-reach manipulator through a hole cut in the top of the tank, and use a variety of end-effectors to mobilize the waste and remove it from the tank. PNL has, with the assistance of Deneb robotics employees, developed a means of using the IGRIP code to perform parametric design of mechanical systems. This method requires no modifications to the IGRIP code, and all design data are stored in the IGRIP workcell. The method is presented in the context of development of a passive articulated mechanism that is used to deliver down-arm services to a gantry robot. The method is completely general, however, and could be used to design a fully articulated manipulator. Briefly, the method involves using IGCALC expressions to control manipulator joint angles, and IGCALC variables to allow user control of link lengths and offsets. This paper presents the method in detail, with examples drawn from PNL`s experience with the gantry robot service-providing mechanism.

  4. Future Directions for Research on Core Competencies

    ERIC Educational Resources Information Center

    Bradshaw, Catherine P.; Guerra, Nancy G.

    2008-01-01

    This concluding commentary highlights common themes that emerged across the chapters in this volume. We identify strengths and limitations of the core competencies framework and discuss the importance of context, culture, and development for understanding the role of the core competencies in preventing risk behavior in adolescence. We also outline…

  5. Raman-Suppressing Coupling for Optical Parametric Oscillator

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Rubiola, Enrico

    2007-01-01

    A Raman-scattering-suppressing input/ output coupling scheme has been devised for a whispering-gallery-mode optical resonator that is used as a four-wave-mixing device to effect an all-optical parametric oscillator. Raman scattering is undesired in such a device because (1) it is a nonlinear process that competes with the desired nonlinear four-wave conversion process involved in optical parametric oscillation and (2) as such, it reduces the power of the desired oscillation and contributes to output noise. The essence of the present input/output coupling scheme is to reduce output loading of the desired resonator modes while increasing output loading of the undesired ones.

  6. Assessment of Social Competence in High-Risk Preschoolers: Evaluation of the Adaptive Social Behavior Inventory (ASBI) across Home and School Settings

    ERIC Educational Resources Information Center

    Greenfield, Daryl B.; Iruka, Iheoma U.; Munis, Pelin

    2004-01-01

    This study evaluates the Adaptive Social Behavior Inventory (ASBI) for assessing pre-school children's social competence across home and school settings. Data were collected on a multi-ethnic sample of 191 3- to 5-year-old children attending Head Start centers. Parents, teachers, and teacher aides rated children similarly on the three ASBI…

  7. An Exploratory Study of the Relationship among Perceived Personal and Social Competence, Health Risk Behaviors, and Academic Achievement of Selected Undergraduate Students

    ERIC Educational Resources Information Center

    Rhodes, Darson L.

    2009-01-01

    A sample of 656 undergraduate students from multiple sections of an introductory nutrition course, a personal health course, and a physical fitness course at a large Midwestern University completed one of four surveys. Using matrix sampling, each participant completed a survey measuring one of four personal and social competence constructs; coping…

  8. Parametric infrared tunable laser system

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Henningsen, T.; Sutter, J. R.

    1980-01-01

    A parametric tunable infrared laser system was built to serve as transmitter for the remote detection and density measurement of pollutant, poisonous, or trace gases in the atmosphere. The system operates with a YAG:Nd laser oscillator amplifier chain which pumps a parametric tunable frequency converter. The completed system produced pulse energies of up to 30 mJ. The output is tunable from 1.5 to 3.6 micrometers at linewidths of 0.2-0.5 /cm (FWHM), although the limits of the tuning range and the narrower line crystals presently in the parametric converter by samples of the higher quality already demonstrated is expected to improve the system performance further.

  9. BRST Cohomology in Beltrami Parametrization

    NASA Astrophysics Data System (ADS)

    Tătaru, Liviu; Vancea, Ion V.

    We study the BRST cohomology within a local conformal Lagrangian field theory model built on a two-dimensional Riemann surface with no boundary. We deal with the case of the complex structure parametrized by the Beltrami differential and the scalar matter fields. The computation of all elements of the BRST cohomology is given.

  10. Predictive Value of Beat-to-Beat QT Variability Index across the Continuum of Left Ventricular Dysfunction: Competing Risks of Non-cardiac or Cardiovascular Death, and Sudden or Non-Sudden Cardiac Death

    PubMed Central

    Tereshchenko, Larisa G.; Cygankiewicz, Iwona; McNitt, Scott; Vazquez, Rafael; Bayes-Genis, Antoni; Han, Lichy; Sur, Sanjoli; Couderc, Jean-Philippe; Berger, Ronald D.; de Luna, Antoni Bayes; Zareba, Wojciech

    2012-01-01

    Background The goal of this study was to determine the predictive value of beat-to-beat QT variability in heart failure (HF) patients across the continuum of left ventricular dysfunction. Methods and Results Beat-to-beat QT variability index (QTVI), heart rate variance (LogHRV), normalized QT variance (QTVN), and coherence between heart rate variability and QT variability have been measured at rest during sinus rhythm in 533 participants of the Muerte Subita en Insuficiencia Cardiaca (MUSIC) HF study (mean age 63.1±11.7; males 70.6%; LVEF >35% in 254 [48%]) and in 181 healthy participants from the Intercity Digital Electrocardiogram Alliance (IDEAL) database. During a median of 3.7 years of follow-up, 116 patients died, 52 from sudden cardiac death (SCD). In multivariate competing risk analyses, the highest QTVI quartile was associated with cardiovascular death [hazard ratio (HR) 1.67(95%CI 1.14-2.47), P=0.009] and in particular with non-sudden cardiac death [HR 2.91(1.69-5.01), P<0.001]. Elevated QTVI separated 97.5% of healthy individuals from subjects at risk for cardiovascular [HR 1.57(1.04-2.35), P=0.031], and non-sudden cardiac death in multivariate competing risk model [HR 2.58(1.13-3.78), P=0.001]. No interaction between QTVI and LVEF was found. QTVI predicted neither non-cardiac death (P=0.546) nor SCD (P=0.945). Decreased heart rate variability (HRV) rather than increased QT variability was the reason for increased QTVI in this study. Conclusions Increased QTVI due to depressed HRV predicts cardiovascular mortality and non-sudden cardiac death, but neither SCD nor excracardiac mortality in HF across the continuum of left ventricular dysfunction. Abnormally augmented QTVI separates 97.5% of healthy individuals from HF patients at risk. PMID:22730411

  11. Experience with parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.

    1993-01-01

    Parametric Binary Dissection (PBD) is a new algorithm that can be used for partitioning graphs embedded in 2- or 3-dimensional space. It partitions explicitly on the basis of nodes + (lambda)x(edges cut), where lambda is the ratio of time to communicate over an edge to the time to compute at a node. The new algorithm is faster than the original binary dissection algorithm and attempts to obtain better partitions than the older algorithm, which only takes nodes into account. The performance of parametric dissection with plain binary dissection on 3 large unstructured 3-d meshes obtained from computational fluid dynamics and on 2 random graphs were compared. It was showm that the new algorithm can usually yield partitions that are substantially superior, but that its performance is heavily dependent on the input data.

  12. Frequency domain optical parametric amplification

    PubMed Central

    Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-01-01

    Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength. PMID:24805968

  13. Parametric Modeling for Fluid Systems

    NASA Technical Reports Server (NTRS)

    Pizarro, Yaritzmar Rosario; Martinez, Jonathan

    2013-01-01

    Fluid Systems involves different projects that require parametric modeling, which is a model that maintains consistent relationships between elements as is manipulated. One of these projects is the Neo Liquid Propellant Testbed, which is part of Rocket U. As part of Rocket U (Rocket University), engineers at NASA's Kennedy Space Center in Florida have the opportunity to develop critical flight skills as they design, build and launch high-powered rockets. To build the Neo testbed; hardware from the Space Shuttle Program was repurposed. Modeling for Neo, included: fittings, valves, frames and tubing, between others. These models help in the review process, to make sure regulations are being followed. Another fluid systems project that required modeling is Plant Habitat's TCUI test project. Plant Habitat is a plan to develop a large growth chamber to learn the effects of long-duration microgravity exposure to plants in space. Work for this project included the design and modeling of a duct vent for flow test. Parametric Modeling for these projects was done using Creo Parametric 2.0.

  14. Competing Risk Analysis of Neurologic versus Nonneurologic Death in Patients Undergoing Radiosurgical Salvage After Whole-Brain Radiation Therapy Failure: Who Actually Dies of Their Brain Metastases?

    SciTech Connect

    Lucas, John T.; Colmer, Hentry G.; White, Lance; Fitzgerald, Nora; Isom, Scott; Bourland, John D.; Laxton, Adrian W.; Tatter, Stephen B.; Chan, Michael D.

    2015-08-01

    Purpose: To estimate the hazard for neurologic (central nervous system, CNS) and nonneurologic (non-CNS) death associated with patient, treatment, and systemic disease status in patients receiving stereotactic radiosurgery after whole-brain radiation therapy (WBRT) failure, using a competing risk model. Patients and Methods: Of 757 patients, 293 experienced recurrence or new metastasis following WBRT. Univariate Cox proportional hazards regression identified covariates for consideration in the multivariate model. Competing risks multivariable regression was performed to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for both CNS and non-CNS death after adjusting for patient, disease, and treatment factors. The resultant model was converted into an online calculator for ease of clinical use. Results: The cumulative incidence of CNS and non-CNS death at 6 and 12 months was 20.6% and 21.6%, and 34.4% and 35%, respectively. Patients with melanoma histology (relative to breast) (aHR 2.7, 95% CI 1.5-5.0), brainstem location (aHR 2.1, 95% CI 1.3-3.5), and number of metastases (aHR 1.09, 95% CI 1.04-1.2) had increased aHR for CNS death. Progressive systemic disease (aHR 0.55, 95% CI 0.4-0.8) and increasing lowest margin dose (aHR 0.97, 95% CI 0.9-0.99) were protective against CNS death. Patients with lung histology (aHR 1.3, 95% CI 1.1-1.9) and progressive systemic disease (aHR 2.14, 95% CI 1.5-3.0) had increased aHR for non-CNS death. Conclusion: Our nomogram provides individual estimates of neurologic death after salvage stereotactic radiosurgery for patients who have failed prior WBRT, based on histology, neuroanatomical location, age, lowest margin dose, and number of metastases after adjusting for their competing risk of death from other causes.

  15. Plasma waves in parametric interactions

    NASA Astrophysics Data System (ADS)

    Yampolsky, Nikolai Andreevich

    The nonlinear laser-plasma interaction is widely discussed in the modern plasma literature with applications to inertial confinement fusion, generation of fast electrons, and amplification of high power radiation. Among nonlinear wave phenomena in plasma, the parametric wave coupling often plays the dominant role in laser-plasma interaction at moderate laser intensities since it is the lowest order nonlinear effect. The plasma wave can mediate the parametric laser coupling with high efficiency. We study the interplay of the parametric laser-plasma interaction and other physical effects which may affect this interaction. We study this interplay with an emphasis on the plasma-based backward Raman amplifier (BRA) based on the three-wave coupling. Three major types of physical effects in the parametric wave coupling are studied. In the first part of the thesis, we find the longitudinal profiles of the interacting waves in cases of interest for pulse compression. We find the solution for the output pulse in backward Raman amplification seeded by a laser pulse of finite duration. We also propose a new scheme for high-power amplification for pulses in the terahertz frequency range. For this scheme, based on the four-wave mixing in a capillary filled with plasma, we find the profile of the output pulse. The second part of this thesis is devoted to transverse effects, which may reduce the focusability of the output pulse in backward Raman amplification. We find that the transverse modulations of the pump can be averaged and do not reduce the amplified pulse focusability if the longitudinal length of these modulations is much smaller than the amplification length. In the third part, we study the kinetic effects. We propose a simplified fluid model for the nonlinear Landau damping of a parametrically driven plasma wave and study the effect of nonlinear Landau damping in backward Raman amplification. This simplified model can be useful not only for understanding complex

  16. Acetabular revision with impaction bone grafting and a cemented polyethylene acetabular component: comparison of the Kaplan-Meier analysis to the competing risk analysis in 62 revisions with 25 to 30 years follow-up.

    PubMed

    Te Stroet, M A J; Keurentjes, J C; Rijnen, W H C; Gardeniers, J W M; Verdonschot, N; Slooff, T J J H; Schreurs, B W

    2015-10-01

    We present the results of 62 consecutive acetabular revisions using impaction bone grafting and a cemented polyethylene acetabular component in 58 patients (13 men and 45 women) after a mean follow-up of 27 years (25 to 30). All patients were prospectively followed. The mean age at revision was 59.2 years (23 to 82). We performed Kaplan-Meier (KM) analysis and also a Competing Risk (CR) analysis because with long-term follow-up, the presence of a competing event (i.e. death) prevents the occurrence of the endpoint of re-revision. A total of 48 patients (52 hips) had died or had been re-revised at final review in March 2011. None of the deaths were related to the surgery. The mean Harris hip score of the ten surviving hips in ten patients was 76 points (45 to 99). The KM survivorship at 25 years for the endpoint 're-revision for any reason' was 58.0% (95% confidence interval (CI) 38 to 73) and for 're-revision for aseptic loosening' 72.1% (95% CI 51 to 85). With the CR analysis we calculated the KM analysis overestimates the failure rate with respectively 74% and 93% for these endpoints. The current study shows that acetabular impaction bone grafting revisions provide good clinical results at over 25 years. PMID:26430007

  17. Competencies: A New Sector.

    ERIC Educational Resources Information Center

    Brophy, Monica; Kiely, Tony

    2002-01-01

    Job analysis of managers in 42 Irish three-star hotels identified the following key management competencies and associated behavioral indicators. The results were used to develop a competency framework for management development. (Contains 29 references.) (SK)

  18. Competencies in Professional Psychology

    ERIC Educational Resources Information Center

    Kaslow, Nadine J.

    2004-01-01

    There has been a burgeoning interest in competency-based education and credentialing in professional psychology. This movement gained momentum at the Competencies Conference: Future Directions in Education and Credentialing in Professional Psychology. After defining professional competence, the author focuses on the identification and delineation…

  19. [Competence in Young Children.

    ERIC Educational Resources Information Center

    White, Burton L.

    Four papers discuss the Harvard Preschool Project whose goal is to learn how to structure the experiences of the first six years of life to encourage maximal development of human competence. To determine what competence at age 6 is, a group of 13 highly competent 6-year-olds of mixed residence, class, and ethnicity were compared to a like group of…

  20. Competencies in HRD. Symposium.

    ERIC Educational Resources Information Center

    2002

    This symposium is comprised of three papers on competencies in human resource development (HRD). "The Development of a Competency Model and Assessment Instrument for Public Sector Leadership and Management Development" (Sharon S. Naquin, Elwood F. Holton III) reports on a streamlined methodology and process used to develop a competency model for…

  1. Do Students Expect Compensation for Wage Risk?

    ERIC Educational Resources Information Center

    Schweri, Juerg; Hartog, Joop; Wolter, Stefan C.

    2011-01-01

    We use a unique data set about the wage distribution that Swiss students expect for themselves ex ante, deriving parametric and non-parametric measures to capture expected wage risk. These wage risk measures are unfettered by heterogeneity which handicapped the use of actual market wage dispersion as risk measure in earlier studies. Students in…

  2. Child-Rearing Practices of Mothers of School-Based Competent Kindergartners Who Are Characterized as At-Risk. Developmentally Appropriate Practice.

    ERIC Educational Resources Information Center

    Lowden, Frances Y.

    1997-01-01

    Examined whether mothers who were at or below the poverty level, members of a minority group, single parents, or who possessed low educational levels can be considered "strong" effective parents. Found that at-risk parents can be and often are effective parents; effective parenting practices and a positive home environment may help ameliorate…

  3. Analysis of parametric transformer with rectifier load

    SciTech Connect

    Ichinokura, O.; Jinzenji, T. ); Tajima, K. )

    1993-03-01

    This paper describes a push-pull parametric transformer constructed using a pair of orthogonal-cores. The operating characteristics of the parametric transformer with a rectifier load were analyzed based on SPICE simulations. The analysis results show good agreement with experiment. It was found that the input surge current of the full-wave rectifier circuit with a smoothing capacitor can be compensated by the parametric transformer. Use of the parametric transformer as a power stabilizer is anticipated owing to its various functions such as for voltage regulation and overload protection.

  4. Software for Managing Parametric Studies

    NASA Technical Reports Server (NTRS)

    Yarrow, Maurice; McCann, Karen M.; DeVivo, Adrian

    2003-01-01

    The Information Power Grid Virtual Laboratory (ILab) is a Practical Extraction and Reporting Language (PERL) graphical-user-interface computer program that generates shell scripts to facilitate parametric studies performed on the Grid. (The Grid denotes a worldwide network of supercomputers used for scientific and engineering computations involving data sets too large to fit on desktop computers.) Heretofore, parametric studies on the Grid have been impeded by the need to create control language scripts and edit input data files painstaking tasks that are necessary for managing multiple jobs on multiple computers. ILab reflects an object-oriented approach to automation of these tasks: All data and operations are organized into packages in order to accelerate development and debugging. A container or document object in ILab, called an experiment, contains all the information (data and file paths) necessary to define a complex series of repeated, sequenced, and/or branching processes. For convenience and to enable reuse, this object is serialized to and from disk storage. At run time, the current ILab experiment is used to generate required input files and shell scripts, create directories, copy data files, and then both initiate and monitor the execution of all computational processes.

  5. Thermal effects in high average power optical parametric amplifiers.

    PubMed

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given. PMID:23455291

  6. Parametric analysis of ATT configurations.

    NASA Technical Reports Server (NTRS)

    Lange, R. H.

    1972-01-01

    This paper describes the results of a Lockheed parametric analysis of the performance, environmental factors, and economics of an advanced commercial transport envisioned for operation in the post-1985 time period. The design parameters investigated include cruise speeds from Mach 0.85 to Mach 1.0, passenger capacities from 200 to 500, ranges of 2800 to 5500 nautical miles, and noise level criteria. NASA high performance configurations and alternate configurations are operated over domestic and international route structures. Indirect and direct costs and return on investment are determined for approximately 40 candidate aircraft configurations. The candidate configurations are input to an aircraft sizing and performance program which includes a subroutine for noise criteria. Comparisons are made between preferred configurations on the basis of maximum return on investment as a function of payload, range, and design cruise speed.

  7. A Comparison of Parametric versus Nonparametric Statistics.

    ERIC Educational Resources Information Center

    Royeen, Charlotte Brasic

    In order to examine the possible effects of violation of assumptions using parametric procedures, this study is an exploratory investigation into the use of parametric versus nonparametric procedures using a multiple case study design. The case study investigation guidelines outlined by Yin served as the methodology. The following univariate…

  8. Parametric Cost Models for Space Telescopes

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2010-01-01

    A study is in-process to develop a multivariable parametric cost model for space telescopes. Cost and engineering parametric data has been collected on 30 different space telescopes. Statistical correlations have been developed between 19 variables of 59 variables sampled. Single Variable and Multi-Variable Cost Estimating Relationships have been developed. Results are being published.

  9. Competence and ability.

    PubMed

    Vogelstein, Eric

    2014-06-01

    It is nearly universally thought that the kind of decision-making competence that gives one a strong prima facie right to make one's own medical decisions essentially involves having an ability (or abilities) of some sort, or having a certain level or degree of ability (or abilities). When put under philosophical scrutiny, however, this kind of theory does not hold up. I will argue that being competent does not essentially involve abilities, and I will propose and defend a theory of decision-making competence according to which one is competent only if one possesses a certain kind of rationality in making treatment decisions. PMID:22845798

  10. Calibrated parametric medical ultrasound imaging.

    PubMed

    Valckx, F M; Thijsse, J M; van Geemen, A J; Rotteveel, J J; Mullaart, R

    2000-01-01

    The goal of this study was to develop a calibrated on-line technique to extract as much diagnostically-relevant information as possible from conventional video-format echograms. The final aim is to improve the diagnostic potentials of medical ultrasound. Video-output images were acquired by a frame grabber board incorporated in a multiprocessor workstation. Calibration images were obtained from a stable tissue-mimicking phantom with known acoustic characteristics. Using these images as reference, depth dependence of the gray level could fairly be corrected for the transducer performance characteristics, for the observer-dependent equipment settings and for attenuation in the examined tissues. Second-order statistical parameters still displayed some nonconsistent depth dependencies. The results obtained with two echoscanners for the same phantom were different; hence, an a posteriori normalization of clinical data with the phantom data is indicated. Prior to processing of clinical echograms,. the anatomical reflections and echoless voids were removed automatically. The final step in the preprocessing concerned the compensation of the overall attenuation in the tissue. A 'sliding window' processing was then applied to a region of interest (ROI) in the 'back-scan converted' images. A number of first and second order statistical texture parameters and acoustical parameters were estimated in each window and assigned to the central pixel. This procedure results in a set of new 'parametric' images of the ROI, which can be inserted in the original echogram (gray value, color) or presented as a color overlay. A clinical example is presented for illustrating the potentials of the developed technique. Depending on the choice of the parameters, four full resolution calibrated parametric images can be calculated and simultaneously displayed within 5 to 20 seconds. In conclusion, an on-line technique has been developed to estimate acoustic and texture parameters with a reduced

  11. Optical filtering enabled by cascaded parametric amplification.

    PubMed

    McKinstrie, C J; Dailey, J M; Agarwal, A; Toliver, P

    2016-06-27

    A cascaded parametric amplifier consists of a first parametric amplifier, which amplifies an input signal and generates an idler, which is a copy of the signal, a signal processor, which controls the phases of the signal and idler, and a second parametric amplifier, which combines the signal and idler in a phase-sensitive manner. In this paper, cascaded parametric amplification is modeled and the conditions required to maximize the constructive-destructive extinction ratio are determined. The results show that a cascaded parametric amplifier can be operated as a filter: A desired signal-idler pair is amplified, whereas undesired signal-idler pairs are deamplified. For the desired signal and idler, the noise figures of the filtering process (input signal-to-noise ratio divided by the output ratios) are only slightly higher than those of the copying process: Signal-processing functionality can be achieved with only a minor degradation in signal quality. PMID:27410581

  12. The Importance of Military Cultural Competence.

    PubMed

    Meyer, Eric G; Writer, Brian W; Brim, William

    2016-03-01

    Military cultural competence has recently gained national attention. Experts have posited that limited outcomes in the treatment of posttraumatic stress disorder and depression in the military may be related to limited familiarity with the military. National surveys have indicated low military cultural competence among providers and limited educational efforts on military culture or pertinent military pathology in medical schools and residency training programs. Military families, with their own unique military cultural identity, have been identified as a population with increased risks associated with deployment. In response to these findings, several curricula regarding military culture have been established and widely distributed. Assessments of military cultural competence have also been developed. The clinical impact of enhanced cultural competence in general has thus far been limited. The military, however, with its highly prescribed cultural identity, may be a model culture for further study. PMID:26830884

  13. Selected Parametric Effects on Materials Flammability Limits

    NASA Technical Reports Server (NTRS)

    Hirsch, David B.; Juarez, Alfredo; Peyton, Gary J.; Harper, Susana A.; Olson, Sandra L.

    2011-01-01

    NASA-STD-(I)-6001B Test 1 is currently used to evaluate the flammability of materials intended for use in habitable environments of U.S. spacecraft. The method is a pass/fail upward flame propagation test conducted in the worst case configuration, which is defined as a combination of a material s thickness, test pressure, oxygen concentration, and temperature that make the material most flammable. Although simple parametric effects may be intuitive (such as increasing oxygen concentrations resulting in increased flammability), combinations of multi-parameter effects could be more complex. In addition, there are a variety of material configurations used in spacecraft. Such configurations could include, for example, exposed free edges where fire propagation may be different when compared to configurations commonly employed in standard testing. Studies involving combined oxygen concentration, pressure, and temperature on flammability limits have been conducted and are summarized in this paper. Additional effects on flammability limits of a material s thickness, mode of ignition, burn-length criteria, and exposed edges are presented. The information obtained will allow proper selection of ground flammability test conditions, support further studies comparing flammability in 1-g with microgravity and reduced gravity environments, and contribute to persuasive scientific cases for rigorous space system fire risk assessments.

  14. Improvement of Statistical Decisions under Parametric Uncertainty

    NASA Astrophysics Data System (ADS)

    Nechval, Nicholas A.; Nechval, Konstantin N.; Purgailis, Maris; Berzins, Gundars; Rozevskis, Uldis

    2011-10-01

    A large number of problems in production planning and scheduling, location, transportation, finance, and engineering design require that decisions be made in the presence of uncertainty. Decision-making under uncertainty is a central problem in statistical inference, and has been formally studied in virtually all approaches to inference. The aim of the present paper is to show how the invariant embedding technique, the idea of which belongs to the authors, may be employed in the particular case of finding the improved statistical decisions under parametric uncertainty. This technique represents a simple and computationally attractive statistical method based on the constructive use of the invariance principle in mathematical statistics. Unlike the Bayesian approach, an invariant embedding technique is independent of the choice of priors. It allows one to eliminate unknown parameters from the problem and to find the best invariant decision rule, which has smaller risk than any of the well-known decision rules. To illustrate the proposed technique, application examples are given.

  15. Parametric and non-parametric modeling of short-term synaptic plasticity. Part I: computational study

    PubMed Central

    Marmarelis, Vasilis Z.; Berger, Theodore W.

    2009-01-01

    Parametric and non-parametric modeling methods are combined to study the short-term plasticity (STP) of synapses in the central nervous system (CNS). The nonlinear dynamics of STP are modeled by means: (1) previously proposed parametric models based on mechanistic hypotheses and/or specific dynamical processes, and (2) non-parametric models (in the form of Volterra kernels) that transforms the presynaptic signals into postsynaptic signals. In order to synergistically use the two approaches, we estimate the Volterra kernels of the parametric models of STP for four types of synapses using synthetic broadband input–output data. Results show that the non-parametric models accurately and efficiently replicate the input–output transformations of the parametric models. Volterra kernels provide a general and quantitative representation of the STP. PMID:18506609

  16. Assessing and Teaching Competence

    ERIC Educational Resources Information Center

    Grant, Terri

    2004-01-01

    The Professional Communication Unit (PCU) at the University of Cape Town (UCT) recently conducted a business communication needs analysis to determine student perceptions of their communicative competence and the teaching strategies being used to develop such competence. Students felt that the specialist, stand-alone communication program was more…

  17. ICT Competences: Algorithmic Thinking

    ERIC Educational Resources Information Center

    Zsakó, László; Szlávi, Péter

    2012-01-01

    A lot has been said about what to teach in ICT in primary and secondary education. There are serious discussions even debates about it. Much less has been said about why ICT should be taught. [1] Competences are related actions and tasks done by people (somebody is competent in a certain field if they are able to solve common tasks related to that…

  18. Curriculum Competencies, 1984.

    ERIC Educational Resources Information Center

    Delaware Technical and Community Coll., Dover. Terry Campus.

    This manual specifies the skills and abilities possessed by the graduates of programs offered by the Terry Campus of Delaware Technical and Community College. First, introductory material discusses the college's competency-based philosophy and the efforts by faculty and administrators to criterion reference the competencies perceived by faculty to…

  19. Core Competence and Education.

    ERIC Educational Resources Information Center

    Holmes, Gary; Hooper, Nick

    2000-01-01

    Outlines the concept of core competence and applies it to postcompulsory education in the United Kingdom. Adopts an educational perspective that suggests accreditation as the core competence of universities. This economic approach suggests that the market trend toward lifetime learning might best be met by institutions developing a core competence…

  20. Global Managers' Career Competencies

    ERIC Educational Resources Information Center

    Cappellen, Tineke; Janssens, Maddy

    2008-01-01

    Purpose: This study aims to empirically examine the career competencies of global managers having world-wide coordination responsibility: knowing-why, knowing-how and knowing-whom career competencies. Design/methodology/approach: Based on in-depth interviews with 45 global managers, the paper analyzes career stories from a content analysis…

  1. Developing Culturally Competent Organizations.

    ERIC Educational Resources Information Center

    Focal Point, 1994

    1994-01-01

    This special issue examines multicultural aspects of services provided by agencies concerned with children's mental health. The lead article is titled "Developing Culturally Competent Organizations" by James L. Mason. This article uses the cultural competence model to discuss an organization's self-evaluation and its planning in the areas of…

  2. Competencies in Ornamental Horticulture

    ERIC Educational Resources Information Center

    Loewen, Curtis E.

    1974-01-01

    Based on the author's dissertation, this article pertains to the identification of competencies for ornamental horticulture workers in Oregon. Findings were based on interviews with 56 ornamental horticulture business employers regarding 100 competencies. The method used can serve as a model for obtaining occupational information to develop and…

  3. Developing Competence at Work

    ERIC Educational Resources Information Center

    Bound, Helen; Lin, Magdalene

    2013-01-01

    In this paper, we explore the relationship between differing conceptualisations of competence, and the implications of these differences for the enacted workplace curriculum and its pedagogical epistemologies. We argue that when competence is understood as a set of stand-alone attributes that reside within an individual, it limits and over…

  4. Competencies and Their Assessment

    ERIC Educational Resources Information Center

    Drisko, James W.

    2014-01-01

    This article explores competencies and methods for their assessment in higher education and in social work's accreditation standards. Many contemporary policy and educational accreditation efforts employ the model of competency assessment. The current emphasis on accountability in higher education, including the Council on Social Work…

  5. Adult Vocational Teacher Competencies.

    ERIC Educational Resources Information Center

    Hole, F. Marvin

    As part of a larger study to investigate the backgrounds and professional inservice needs of part-time adult vocational teachers in Pennsylvania, research was conducted to identify and assess adult vocational teacher competencies. Following a literature review, a survey instrument was devised which listed thirty-four competencies (basically…

  6. Profiles of Algebraic Competence

    ERIC Educational Resources Information Center

    Humberstone, J.; Reeve, R.A.

    2008-01-01

    The algebraic competence of 72 12-year-old female students was examined to identify profiles of understanding reflecting different algebraic knowledge states. Beginning algebraic competence (mapping abilities: word-to-symbol and vice versa, classifying, and solving equations) was assessed. One week later, the nature of assistance required to map…

  7. Cultural Competence Revisited

    ERIC Educational Resources Information Center

    Garran, Ann Marie; Werkmeister Rozas, Lisa

    2013-01-01

    In 2001, the National Association of Social Workers (NASW) adopted 10 discrete standards of culturally competent practice which undergird our commitment to diversity and social justice. The concept of intersectionality is newly emerging in social work, though, causing us to reflect on our current conceptualizations of cultural competence.…

  8. Minimum Competency Testing. Update.

    ERIC Educational Resources Information Center

    Beard, Jacob G.

    During the last decade many school systems began to define minimum levels of competency for their students and to construct tests to measure whether students had achieved these minimums. Many states have passed laws which require high school students to pass minimum competency tests in order to graduate. This digest overviews four areas of…

  9. Competencies for Gerontological Counseling.

    ERIC Educational Resources Information Center

    Myers, Jane E.; Schwiebert, Valerie L.

    Gerontological counseling as a counseling specialty spans only 20 years. This text incorporates into its framework the 16 Minimum Essential Competencies of gerontological counseling that have been developed over the past two decades. These competencies focus on the knowledge and skills required to be an effective counselor for older persons and…

  10. Drafting. Competency Based Curriculum.

    ERIC Educational Resources Information Center

    Everly, Al; And Others

    This competency based drafting curriculum is presented in seven specialization sections with units in each section containing a competency statement, performance objective, learning activities, evaluation, and quiz or problem sheets. Some units also contain answer sheets and/or handout sheets. Sections and number of units presented are (1) basic…

  11. Competency and consent in dementia.

    PubMed

    Fellows, L K

    1998-07-01

    Health care for demented older persons presents a range of ethical dilemmas. The disease process affects cognitive abilities, making competency a central issue. The syndrome of dementia carries a complex social overlay that colors perceptions of these patients and of their capacity for making decisions. An argument is made for a coherent, ethically based decision-making process that can be applied across the whole spectrum of dementia severity. The major ethical principles implicated in assessing a patient's ability to consent to treatment are reviewed. A sliding scale model of capacity is presented, in which the patient's ability to decide is weighed against the risk associated with the treatment decision in question. This model preserves the autonomy of the demented patient while minimizing the potential for harm. In situations where the patient is deemed incapable, two approaches that can be applied to making treatment decisions are contrasted. The 'prior competent choice' standard stresses the values that the patient held while competent. The 'best interests' standard moves the focus to the patient's subjective experience at the time the treatment is considered. The relative merits of these two concepts are evaluated in the context of dementia. Surveys of actual decision-making practice are contrasted with ethical and legal principles. The challenges inherent to applying the best interests standard are discussed. Despite the pitfalls, this standard offers an opportunity to restore the demented patient's sense of self. PMID:9670887

  12. An Annotated Bibliography on Competencies.

    ERIC Educational Resources Information Center

    Paulson, Karen

    2001-01-01

    Surveys the published literature and Internet-based resources on competencies, and presents resources in five sections: general introduction to competencies in postsecondary education, competencies for entry into postsecondary education, competencies within postsecondary education, competencies for exit from postsecondary education, and…

  13. Characteristics of stereo reproduction with parametric loudspeakers

    NASA Astrophysics Data System (ADS)

    Aoki, Shigeaki; Toba, Masayoshi; Tsujita, Norihisa

    2012-05-01

    A parametric loudspeaker utilizes nonlinearity of a medium and is known as a super-directivity loudspeaker. The parametric loudspeaker is one of the prominent applications of nonlinear ultrasonics. So far, the applications have been limited monaural reproduction sound system for public address in museum, station and street etc. In this paper, we discussed characteristics of stereo reproduction with two parametric loudspeakers by comparing with those with two ordinary dynamic loudspeakers. In subjective tests, three typical listening positions were selected to investigate the possibility of correct sound localization in a wide listening area. The binaural information was ILD (Interaural Level Difference) or ITD (Interaural Time Delay). The parametric loudspeaker was an equilateral hexagon. The inner and outer diameters were 99 and 112 mm, respectively. Signals were 500 Hz, 1 kHz, 2 kHz and 4 kHz pure tones and pink noise. Three young males listened to test signals 10 times in each listening condition. Subjective test results showed that listeners at the three typical listening positions perceived correct sound localization of all signals using the parametric loudspeakers. It was almost similar to those using the ordinary dynamic loudspeakers, however, except for the case of sinusoidal waves with ITD. It was determined the parametric loudspeaker could exclude the contradiction between the binaural information ILD and ITD that occurred in stereo reproduction with ordinary dynamic loudspeakers because the super directivity of parametric loudspeaker suppressed the cross talk components.

  14. Ionization Cooling using Parametric Resonances

    SciTech Connect

    Johnson, Rolland P.

    2008-06-07

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  15. Competencies Framework for Climate Services.

    NASA Astrophysics Data System (ADS)

    Aguilar, Enric

    2016-04-01

    The World Climate Conference-3 (Geneva, 2009) established the Global Framework for Climate Services (GFCS) to enable better management of the risks of climate variability and change and adaptation to climate change at all levels, through development and incorporation of science-based climate information and prediction into planning, policy and practice. The GFCS defines Climate Services as the result of transforming climate data into climate information in a way that responds to user needs and assists decision-making by individuals and organizations. Capacity Development is a cross-cutting pillar of the GFCS to ensure that services are provided by institutions with professionals whom achieved the adequate set of competencies recommended by WMO, which are yet to be fully defined. The WMO-Commission for Climatology Expert Team on Education and Training, ET-ETR, has been working to define a Competencies Framework for Climate Services to help the institutions to deliver high quality climate services in compliance with WMO standards and regulations, specifically those defined by WMO's Commission for Climatology and the GFCS. This framework is based in 5 areas or competence, closely associated to the areas of work of climate services providers: create and manage climate data sets; derive products from climate data; create and/or interpret climate forecasts and model output; ensure the quality of climate information and services; communicate climatological information with users. With this contribution, we intend to introduce to a wider audience the rationale behind these 5 top-level competency statements and the performance criteria associated with them, as well as the plans of the ET-ETR for further developing them into an instrument to support education and training within the WMO members, specially the National Meteorological and Hydrological Services.

  16. Self-seeding ring optical parametric oscillator

    DOEpatents

    Smith, Arlee V.; Armstrong, Darrell J.

    2005-12-27

    An optical parametric oscillator apparatus utilizing self-seeding with an external nanosecond-duration pump source to generate a seed pulse resulting in increased conversion efficiency. An optical parametric oscillator with a ring configuration are combined with a pump that injection seeds the optical parametric oscillator with a nanosecond duration, mJ pulse in the reverse direction as the main pulse. A retroreflecting means outside the cavity injects the seed pulse back into the cavity in the direction of the main pulse to seed the main pulse, resulting in higher conversion efficiency.

  17. Optimal Parametric Feedback Excitation of Nonlinear Oscillators

    NASA Astrophysics Data System (ADS)

    Braun, David J.

    2016-01-01

    An optimal parametric feedback excitation principle is sought, found, and investigated. The principle is shown to provide an adaptive resonance condition that enables unprecedentedly robust movement generation in a large class of oscillatory dynamical systems. Experimental demonstration of the theory is provided by a nonlinear electronic circuit that realizes self-adaptive parametric excitation without model information, signal processing, and control computation. The observed behavior dramatically differs from the one achievable using classical parametric modulation, which is fundamentally limited by uncertainties in model information and nonlinear effects inevitably present in real world applications.

  18. Optimal Parametric Feedback Excitation of Nonlinear Oscillators.

    PubMed

    Braun, David J

    2016-01-29

    An optimal parametric feedback excitation principle is sought, found, and investigated. The principle is shown to provide an adaptive resonance condition that enables unprecedentedly robust movement generation in a large class of oscillatory dynamical systems. Experimental demonstration of the theory is provided by a nonlinear electronic circuit that realizes self-adaptive parametric excitation without model information, signal processing, and control computation. The observed behavior dramatically differs from the one achievable using classical parametric modulation, which is fundamentally limited by uncertainties in model information and nonlinear effects inevitably present in real world applications. PMID:26871336

  19. Airy beam optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Aadhi, A.; Chaitanya, N. Apurv; Jabir, M. V.; Vaity, Pravin; Singh, R. P.; Samanta, G. K.

    2016-05-01

    Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51–1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond).

  20. Airy beam optical parametric oscillator.

    PubMed

    Aadhi, A; Chaitanya, N Apurv; Jabir, M V; Vaity, Pravin; Singh, R P; Samanta, G K

    2016-01-01

    Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51-1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond). PMID:27143582

  1. Airy beam optical parametric oscillator

    PubMed Central

    Aadhi, A.; Chaitanya, N. Apurv; Jabir, M. V.; Vaity, Pravin; Singh, R. P.; Samanta, G. K.

    2016-01-01

    Airy beam, a non-diffracting waveform, has peculiar properties of self-healing and self-acceleration. Due to such unique properties, the Airy beam finds many applications including curved plasma wave-guiding, micro-particle manipulation, optically mediated particle clearing, long distance communication, and nonlinear frequency conversion. However, many of these applications including laser machining of curved structures, generation of curved plasma channels, guiding of electric discharges in a curved path, study of nonlinear propagation dynamics, and nonlinear interaction demand Airy beam with high power, energy, and wavelength tunability. Till date, none of the Airy beam sources have all these features in a single device. Here, we report a new class of coherent sources based on cubic phase modulation of a singly-resonant optical parametric oscillator (OPO), producing high-power, continuous-wave (cw), tunable radiation in 2-D Airy intensity profile existing over a length >2 m. Based on a MgO-doped periodically poled LiNbO3 crystal pumped at 1064 nm, the Airy beam OPO produces output power more than 8 W, and wavelength tunability across 1.51–1.97 μm. This demonstration gives new direction for the development of sources of arbitrary structured beams at any wavelength, power, and energy in all time scales (cw to femtosecond). PMID:27143582

  2. Parametric X-Ray Radiation

    NASA Astrophysics Data System (ADS)

    Shchagin, Alexander

    1997-10-01

    The main PXR properties [1,2] are considered in the paper: energy, width, smooth tuning of monochromatic PXR spectral line; fine structure and absolute differential yields of PXR in the vicinity of and at angular distances from Brag directions; angular spread of the PXR beam; the influence of incident electron energy and of the density effect on the PXR properties; linear polarization of PXR; background in PXR spectra. Experimental setups for linacs and the results of measurements are discussed. Experimental data are compared to theoretical calculations at PXR energies between 5 and 400 keV for incident electron energies ranging from 15 to 1200 MeV. Possible applications of PXR as a new source of a bright, tunable X-ray beam in science and industry are discussed. [1] A.V. Shchagin and N.A. Khizhnyak, NIM B119, 115-122 (1996). [2] A.V. Shchagin and X.K. Maruyama, "Parametric X-rays", a chapter in the book "Accelerator-based Atomic Physics Techniques and Applications", edited by S.M. Shafroth and J.C. Austin, AIP Press, 1997, pp 279-307.

  3. Compassion Competence in Nurses.

    PubMed

    Lee, Youngjin; Seomun, GyeongAe

    2016-01-01

    The purpose of study was to identify the attributes of the concept of compassion competence for nurses. A hybrid model was used to develop the concept, which included fieldwork performed. The concept of compassion competence was found to possess 3 dimensions: (a) acquisition of a wealth of knowledge; (b) development of skills of emotional communication, sensitivity, insight, and self-regulation; and (c) development of attitudes of respect and empathy, and maintenance of occupational distance. Compassion competence could be useful for developing ways to enhance the knowledge, skills, and attitudes required for nurses to provide compassionate care in various nursing practices. PMID:27149235

  4. Developing emergency nursing competence.

    PubMed

    Proehl, Jean A

    2002-03-01

    Developing and maintaining the competence emergency nurses need is an important function of emergency clinical nurse specialists (CNS), educators, and other members of the emergency department (ED) leadership team. A thorough orientation is the first and most important step in developing the competence of emergency nurses. After orientation, the challenge is to maintain currency of practice in the face of incessant change such as new medications, new equipment, and new therapies in emergency care. This article focuses on the orientation of emergency nurses. A related article in this issue addresses assessment of competency. PMID:11818264

  5. Engineering artificial Hamiltonians with parametric superconducting circuits

    NASA Astrophysics Data System (ADS)

    Lu, Yao; Chakram, Srivatsan; Leung, Nelson; Naik, Ravi; Earnest, Nathan; Groszkowski, Peter; Koch, Jens; Kapit, Eliot; Schuster, David

    One major challenge in building a large scale quantum computer is to generate and manipulate interactions between its many qubits. One promising approach is to use parametric flux or voltage modulation to realize effective interactions between different components of superconducting circuits, generating artificial Hamiltonians that are suitable for various quantum computation tasks, which might be difficult to achieve through other means. We propose a parametric superconducting circuit where transmon qubits and resonators are coupled to a flux-modulated parametric coupler. We show that with this device, arbitrary pairs of qubits or resonators in the circuit can be selectively and simultaneously brought into resonance with each other and swap excitations at a controllable rate. This allows for the creation of various artificial circuit Hamiltonians that are suitable for a number of applications such as single qubit state stablization, parametric qubit state readout, autonomous error correction and so on.

  6. Parametric models for samples of random functions

    SciTech Connect

    Grigoriu, M.

    2015-09-15

    A new class of parametric models, referred to as sample parametric models, is developed for random elements that match sample rather than the first two moments and/or other global properties of these elements. The models can be used to characterize, e.g., material properties at small scale in which case their samples represent microstructures of material specimens selected at random from a population. The samples of the proposed models are elements of finite-dimensional vector spaces spanned by samples, eigenfunctions of Karhunen–Loève (KL) representations, or modes of singular value decompositions (SVDs). The implementation of sample parametric models requires knowledge of the probability laws of target random elements. Numerical examples including stochastic processes and random fields are used to demonstrate the construction of sample parametric models, assess their accuracy, and illustrate how these models can be used to solve efficiently stochastic equations.

  7. A uniform parametrization of moment tensors

    NASA Astrophysics Data System (ADS)

    Tape, Walter; Tape, Carl

    2015-09-01

    A moment tensor is a 3 × 3 symmetric matrix that expresses an earthquake source. We construct a parametrization of the 5-D space of all moment tensors of unit norm. The coordinates associated with the parametrization are closely related to moment tensor orientations and source types. The parametrization is uniform, in the sense that equal volumes in the coordinate domain of the parametrization correspond to equal volumes of moment tensors. Uniformly distributed points in the coordinate domain therefore give uniformly distributed moment tensors. A cartesian grid in the coordinate domain can be used to search efficiently over moment tensors. We find that uniformly distributed moment tensors have uniformly distributed orientations (eigenframes), but that their source types (eigenvalue triples) are distributed so as to favour double couples.

  8. Parametrically disciplined operation of a vibratory gyroscope

    NASA Technical Reports Server (NTRS)

    Shcheglov, Kirill V. (Inventor); Hayworth, Ken J. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

    2008-01-01

    Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.

  9. Analytic parametrization for nuclear form factors

    SciTech Connect

    Atkin, G.; Dumbrajs, O.

    1982-08-01

    A new analytic parametrization of the nuclear form factor is developed using a factorization theorem. We show that the nuclear form factor can be represented in terms of its real zeros and its asymptotic behavior. The parametrization is applied to nuclear form factor data of /sup 3/He and /sup 4/He. Our results suggest that further diffraction minima can be expected at higher momentum transfer where experiments have not yet been made.

  10. Observation of Parametric Instability in Advanced LIGO.

    PubMed

    Evans, Matthew; Gras, Slawek; Fritschel, Peter; Miller, John; Barsotti, Lisa; Martynov, Denis; Brooks, Aidan; Coyne, Dennis; Abbott, Rich; Adhikari, Rana X; Arai, Koji; Bork, Rolf; Kells, Bill; Rollins, Jameson; Smith-Lefebvre, Nicolas; Vajente, Gabriele; Yamamoto, Hiroaki; Adams, Carl; Aston, Stuart; Betzweiser, Joseph; Frolov, Valera; Mullavey, Adam; Pele, Arnaud; Romie, Janeen; Thomas, Michael; Thorne, Keith; Dwyer, Sheila; Izumi, Kiwamu; Kawabe, Keita; Sigg, Daniel; Derosa, Ryan; Effler, Anamaria; Kokeyama, Keiko; Ballmer, Stefan; Massinger, Thomas J; Staley, Alexa; Heinze, Matthew; Mueller, Chris; Grote, Hartmut; Ward, Robert; King, Eleanor; Blair, David; Ju, Li; Zhao, Chunnong

    2015-04-24

    Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been observed in a kilometer-scale interferometer. In this Letter, we describe the first observation of parametric instability in a gravitational wave detector, and the means by which it has been removed as a barrier to progress. PMID:25955042