Sample records for parametric competing risks

  1. A Semi-parametric Transformation Frailty Model for Semi-competing Risks Survival Data

    PubMed Central

    Jiang, Fei; Haneuse, Sebastien

    2016-01-01

    In the analysis of semi-competing risks data interest lies in estimation and inference with respect to a so-called non-terminal event, the observation of which is subject to a terminal event. Multi-state models are commonly used to analyse such data, with covariate effects on the transition/intensity functions typically specified via the Cox model and dependence between the non-terminal and terminal events specified, in part, by a unit-specific shared frailty term. To ensure identifiability, the frailties are typically assumed to arise from a parametric distribution, specifically a Gamma distribution with mean 1.0 and variance, say, σ2. When the frailty distribution is misspecified, however, the resulting estimator is not guaranteed to be consistent, with the extent of asymptotic bias depending on the discrepancy between the assumed and true frailty distributions. In this paper, we propose a novel class of transformation models for semi-competing risks analysis that permit the non-parametric specification of the frailty distribution. To ensure identifiability, the class restricts to parametric specifications of the transformation and the error distribution; the latter are flexible, however, and cover a broad range of possible specifications. We also derive the semi-parametric efficient score under the complete data setting and propose a non-parametric score imputation method to handle right censoring; consistency and asymptotic normality of the resulting estimators is derived and small-sample operating characteristics evaluated via simulation. Although the proposed semi-parametric transformation model and non-parametric score imputation method are motivated by the analysis of semi-competing risks data, they are broadly applicable to any analysis of multivariate time-to-event outcomes in which a unit-specific shared frailty is used to account for correlation. Finally, the proposed model and estimation procedures are applied to a study of hospital readmission among

  2. An EM-based semi-parametric mixture model approach to the regression analysis of competing-risks data.

    PubMed

    Ng, S K; McLachlan, G J

    2003-04-15

    We consider a mixture model approach to the regression analysis of competing-risks data. Attention is focused on inference concerning the effects of factors on both the probability of occurrence and the hazard rate conditional on each of the failure types. These two quantities are specified in the mixture model using the logistic model and the proportional hazards model, respectively. We propose a semi-parametric mixture method to estimate the logistic and regression coefficients jointly, whereby the component-baseline hazard functions are completely unspecified. Estimation is based on maximum likelihood on the basis of the full likelihood, implemented via an expectation-conditional maximization (ECM) algorithm. Simulation studies are performed to compare the performance of the proposed semi-parametric method with a fully parametric mixture approach. The results show that when the component-baseline hazard is monotonic increasing, the semi-parametric and fully parametric mixture approaches are comparable for mildly and moderately censored samples. When the component-baseline hazard is not monotonic increasing, the semi-parametric method consistently provides less biased estimates than a fully parametric approach and is comparable in efficiency in the estimation of the parameters for all levels of censoring. The methods are illustrated using a real data set of prostate cancer patients treated with different dosages of the drug diethylstilbestrol. Copyright 2003 John Wiley & Sons, Ltd.

  3. Meta-analysis for aggregated survival data with competing risks: a parametric approach using cumulative incidence functions.

    PubMed

    Bonofiglio, Federico; Beyersmann, Jan; Schumacher, Martin; Koller, Michael; Schwarzer, Guido

    2016-09-01

    Meta-analysis of a survival endpoint is typically based on the pooling of hazard ratios (HRs). If competing risks occur, the HRs may lose translation into changes of survival probability. The cumulative incidence functions (CIFs), the expected proportion of cause-specific events over time, re-connect the cause-specific hazards (CSHs) to the probability of each event type. We use CIF ratios to measure treatment effect on each event type. To retrieve information on aggregated, typically poorly reported, competing risks data, we assume constant CSHs. Next, we develop methods to pool CIF ratios across studies. The procedure computes pooled HRs alongside and checks the influence of follow-up time on the analysis. We apply the method to a medical example, showing that follow-up duration is relevant both for pooled cause-specific HRs and CIF ratios. Moreover, if all-cause hazard and follow-up time are large enough, CIF ratios may reveal additional information about the effect of treatment on the cumulative probability of each event type. Finally, to improve the usefulness of such analysis, better reporting of competing risks data is needed. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Accelerated failure time models for semi-competing risks data in the presence of complex censoring.

    PubMed

    Lee, Kyu Ha; Rondeau, Virginie; Haneuse, Sebastien

    2017-12-01

    Statistical analyses that investigate risk factors for Alzheimer's disease (AD) are often subject to a number of challenges. Some of these challenges arise due to practical considerations regarding data collection such that the observation of AD events is subject to complex censoring including left-truncation and either interval or right-censoring. Additional challenges arise due to the fact that study participants under investigation are often subject to competing forces, most notably death, that may not be independent of AD. Towards resolving the latter, researchers may choose to embed the study of AD within the "semi-competing risks" framework for which the recent statistical literature has seen a number of advances including for the so-called illness-death model. To the best of our knowledge, however, the semi-competing risks literature has not fully considered analyses in contexts with complex censoring, as in studies of AD. This is particularly the case when interest lies with the accelerated failure time (AFT) model, an alternative to the traditional multiplicative Cox model that places emphasis away from the hazard function. In this article, we outline a new Bayesian framework for estimation/inference of an AFT illness-death model for semi-competing risks data subject to complex censoring. An efficient computational algorithm that gives researchers the flexibility to adopt either a fully parametric or a semi-parametric model specification is developed and implemented. The proposed methods are motivated by and illustrated with an analysis of data from the Adult Changes in Thought study, an on-going community-based prospective study of incident AD in western Washington State. © 2017, The International Biometric Society.

  5. 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

  6. 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

  7. [Survival analysis with competing risks: estimating failure probability].

    PubMed

    Llorca, Javier; Delgado-Rodríguez, Miguel

    2004-01-01

    To show the impact of competing risks of death on survival analysis. We provide an example of survival time without chronic rejection after heart transplantation, where death before rejection acts as a competing risk. Using a computer simulation, we compare the Kaplan-Meier estimator and the multiple decrement model. The Kaplan-Meier method overestimated the probability of rejection. Next, we illustrate the use of the multiple decrement model to analyze secondary end points (in our example: death after rejection). Finally, we discuss Kaplan-Meier assumptions and why they fail in the presence of competing risks. Survival analysis should be adjusted for competing risks of death to avoid overestimation of the risk of rejection produced with the Kaplan-Meier method.

  8. Competing risk bias was common in Kaplan-Meier risk estimates published in prominent medical journals.

    PubMed

    van Walraven, Carl; McAlister, Finlay A

    2016-01-01

    Risk estimates from Kaplan-Meier curves are well known to medical researchers, reviewers, and editors. In this study, we determined the proportion of Kaplan-Meier analyses published in prominent medical journals that are potentially biased because of competing events ("competing risk bias"). We randomly selected 100 studies that had at least one Kaplan-Meier analysis and were recently published in prominent medical journals. Susceptibility to competing risk bias was determined by examining the outcome and potential competing events. In susceptible studies, bias was quantified using a previously validated prediction model when the number of outcomes and competing events were given. Forty-six studies (46%) contained Kaplan-Meier analyses susceptible to competing risk bias. Sixteen studies (34.8%) susceptible to competing risk cited the number of outcomes and competing events; in six of these studies (6/16, 37.5%), the outcome risk from the Kaplan-Meier estimate (relative to the true risk) was biased upward by 10% or more. Almost half of Kaplan-Meier analyses published in medical journals are susceptible to competing risk bias and may overestimate event risk. This bias was found to be quantitatively important in a third of such studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Multilevel joint competing risk models

    NASA Astrophysics Data System (ADS)

    Karunarathna, G. H. S.; Sooriyarachchi, M. R.

    2017-09-01

    Joint modeling approaches are often encountered for different outcomes of competing risk time to event and count in many biomedical and epidemiology studies in the presence of cluster effect. Hospital length of stay (LOS) has been the widely used outcome measure in hospital utilization due to the benchmark measurement for measuring multiple terminations such as discharge, transferred, dead and patients who have not completed the event of interest at the follow up period (censored) during hospitalizations. Competing risk models provide a method of addressing such multiple destinations since classical time to event models yield biased results when there are multiple events. In this study, the concept of joint modeling has been applied to the dengue epidemiology in Sri Lanka, 2006-2008 to assess the relationship between different outcomes of LOS and platelet count of dengue patients with the district cluster effect. Two key approaches have been applied to build up the joint scenario. In the first approach, modeling each competing risk separately using the binary logistic model, treating all other events as censored under the multilevel discrete time to event model, while the platelet counts are assumed to follow a lognormal regression model. The second approach is based on the endogeneity effect in the multilevel competing risks and count model. Model parameters were estimated using maximum likelihood based on the Laplace approximation. Moreover, the study reveals that joint modeling approach yield more precise results compared to fitting two separate univariate models, in terms of AIC (Akaike Information Criterion).

  10. Vascular disease, ESRD, and death: interpreting competing risk analyses.

    PubMed

    Grams, Morgan E; Coresh, Josef; Segev, Dorry L; Kucirka, Lauren M; Tighiouart, Hocine; Sarnak, Mark J

    2012-10-01

    Vascular disease, a common condition in CKD, is a risk factor for mortality and ESRD. Optimal patient care requires accurate estimation and ordering of these competing risks. This is a prospective cohort study of screened (n=885) and randomized participants (n=837) in the Modification of Diet in Renal Disease study (original study enrollment, 1989-1992), evaluating the association of vascular disease with ESRD and pre-ESRD mortality using standard survival analysis and competing risk regression. The method of analysis resulted in markedly different estimates. Cumulative incidence by standard analysis (censoring at the competing event) implied that, with vascular disease, the 15-year incidence was 66% and 51% for ESRD and pre-ESRD death, respectively. A more accurate representation of absolute risk was estimated with competing risk regression: 15-year incidence was 54% and 29% for ESRD and pre-ESRD death, respectively. For the association of vascular disease with pre-ESRD death, estimates of relative risk by the two methods were similar (standard survival analysis adjusted hazard ratio, 1.63; 95% confidence interval, 1.20-2.20; competing risk regression adjusted subhazard ratio, 1.57; 95% confidence interval, 1.15-2.14). In contrast, the hazard and subhazard ratios differed substantially for other associations, such as GFR and pre-ESRD mortality. When competing events exist, absolute risk is better estimated using competing risk regression, but etiologic associations by this method must be carefully interpreted. The presence of vascular disease in CKD decreases the likelihood of survival to ESRD, independent of age and other risk factors.

  11. Intervening on risk factors for coronary heart disease: an application of the parametric g-formula.

    PubMed

    Taubman, Sarah L; Robins, James M; Mittleman, Murray A; Hernán, Miguel A

    2009-12-01

    Estimating the population risk of disease under hypothetical interventions--such as the population risk of coronary heart disease (CHD) were everyone to quit smoking and start exercising or to start exercising if diagnosed with diabetes--may not be possible using standard analytic techniques. The parametric g-formula, which appropriately adjusts for time-varying confounders affected by prior exposures, is especially well suited to estimating effects when the intervention involves multiple factors (joint interventions) or when the intervention involves decisions that depend on the value of evolving time-dependent factors (dynamic interventions). We describe the parametric g-formula, and use it to estimate the effect of various hypothetical lifestyle interventions on the risk of CHD using data from the Nurses' Health Study. Over the period 1982-2002, the 20-year risk of CHD in this cohort was 3.50%. Under a joint intervention of no smoking, increased exercise, improved diet, moderate alcohol consumption and reduced body mass index, the estimated risk was 1.89% (95% confidence interval: 1.46-2.41). We discuss whether the assumptions required for the validity of the parametric g-formula hold in the Nurses' Health Study data. This work represents the first large-scale application of the parametric g-formula in an epidemiologic cohort study.

  12. Vascular Disease, ESRD, and Death: Interpreting Competing Risk Analyses

    PubMed Central

    Coresh, Josef; Segev, Dorry L.; Kucirka, Lauren M.; Tighiouart, Hocine; Sarnak, Mark J.

    2012-01-01

    Summary Background and objectives Vascular disease, a common condition in CKD, is a risk factor for mortality and ESRD. Optimal patient care requires accurate estimation and ordering of these competing risks. Design, setting, participants, & measurements This is a prospective cohort study of screened (n=885) and randomized participants (n=837) in the Modification of Diet in Renal Disease study (original study enrollment, 1989–1992), evaluating the association of vascular disease with ESRD and pre-ESRD mortality using standard survival analysis and competing risk regression. Results The method of analysis resulted in markedly different estimates. Cumulative incidence by standard analysis (censoring at the competing event) implied that, with vascular disease, the 15-year incidence was 66% and 51% for ESRD and pre-ESRD death, respectively. A more accurate representation of absolute risk was estimated with competing risk regression: 15-year incidence was 54% and 29% for ESRD and pre-ESRD death, respectively. For the association of vascular disease with pre-ESRD death, estimates of relative risk by the two methods were similar (standard survival analysis adjusted hazard ratio, 1.63; 95% confidence interval, 1.20–2.20; competing risk regression adjusted subhazard ratio, 1.57; 95% confidence interval, 1.15–2.14). In contrast, the hazard and subhazard ratios differed substantially for other associations, such as GFR and pre-ESRD mortality. Conclusions When competing events exist, absolute risk is better estimated using competing risk regression, but etiologic associations by this method must be carefully interpreted. The presence of vascular disease in CKD decreases the likelihood of survival to ESRD, independent of age and other risk factors. PMID:22859747

  13. Geometry of the q-exponential distribution with dependent competing risks and accelerated life testing

    NASA Astrophysics Data System (ADS)

    Zhang, Fode; Shi, Yimin; Wang, Ruibing

    2017-02-01

    In the information geometry suggested by Amari (1985) and Amari et al. (1987), a parametric statistical model can be regarded as a differentiable manifold with the parameter space as a coordinate system. Note that the q-exponential distribution plays an important role in Tsallis statistics (see Tsallis, 2009), this paper investigates the geometry of the q-exponential distribution with dependent competing risks and accelerated life testing (ALT). A copula function based on the q-exponential function, which can be considered as the generalized Gumbel copula, is discussed to illustrate the structure of the dependent random variable. Employing two iterative algorithms, simulation results are given to compare the performance of estimations and levels of association under different hybrid progressively censoring schemes (HPCSs).

  14. Semi-Competing Risks Data Analysis: Accounting for Death as a Competing Risk When the Outcome of Interest Is Nonterminal.

    PubMed

    Haneuse, Sebastien; Lee, Kyu Ha

    2016-05-01

    Hospital readmission is a key marker of quality of health care. Notwithstanding its widespread use, however, it remains controversial in part because statistical methods used to analyze readmission, primarily logistic regression and related models, may not appropriately account for patients who die before experiencing a readmission event within the time frame of interest. Toward resolving this, we describe and illustrate the semi-competing risks framework, which refers to the general setting where scientific interest lies with some nonterminal event (eg, readmission), the occurrence of which is subject to a terminal event (eg, death). Although several statistical analysis methods have been proposed for semi-competing risks data, we describe in detail the use of illness-death models primarily because of their relation to well-known methods for survival analysis and the availability of software. We also describe and consider in detail several existing approaches that could, in principle, be used to analyze semi-competing risks data, including composite end point and competing risks analyses. Throughout we illustrate the ideas and methods using data on N=49 763 Medicare beneficiaries hospitalized between 2011 and 2013 with a principle discharge diagnosis of heart failure. © 2016 American Heart Association, Inc.

  15. The application of cure models in the presence of competing risks: a tool for improved risk communication in population-based cancer patient survival.

    PubMed

    Eloranta, Sandra; Lambert, Paul C; Andersson, Therese M-L; Björkholm, Magnus; Dickman, Paul W

    2014-09-01

    Quantifying cancer patient survival from the perspective of cure is clinically relevant. However, most cure models estimate cure assuming no competing causes of death. We use a relative survival framework to demonstrate how flexible parametric cure models can be used in combination with competing-risks theory to incorporate noncancer deaths. Under a model that incorporates statistical cure, we present the probabilities that cancer patients (1) have died from their cancer, (2) have died from other causes, (3) will eventually die from their cancer, or (4) will eventually die from other causes, all as a function of time since diagnosis. We further demonstrate how conditional probabilities can be used to update the prognosis among survivors (eg, at 1 or 5 years after diagnosis) by summarizing the proportion of patients who will not die from their cancer. The proposed method is applied to Swedish population-based data for persons diagnosed with melanoma, colon cancer, or acute myeloid leukemia between 1973 and 2007.

  16. Crude incidence in two-phase designs in the presence of competing risks.

    PubMed

    Rebora, Paola; Antolini, Laura; Glidden, David V; Valsecchi, Maria Grazia

    2016-01-11

    In many studies, some information might not be available for the whole cohort, some covariates, or even the outcome, might be ascertained in selected subsamples. These studies are part of a broad category termed two-phase studies. Common examples include the nested case-control and the case-cohort designs. For two-phase studies, appropriate weighted survival estimates have been derived; however, no estimator of cumulative incidence accounting for competing events has been proposed. This is relevant in the presence of multiple types of events, where estimation of event type specific quantities are needed for evaluating outcome. We develop a non parametric estimator of the cumulative incidence function of events accounting for possible competing events. It handles a general sampling design by weights derived from the sampling probabilities. The variance is derived from the influence function of the subdistribution hazard. The proposed method shows good performance in simulations. It is applied to estimate the crude incidence of relapse in childhood acute lymphoblastic leukemia in groups defined by a genotype not available for everyone in a cohort of nearly 2000 patients, where death due to toxicity acted as a competing event. In a second example the aim was to estimate engagement in care of a cohort of HIV patients in resource limited setting, where for some patients the outcome itself was missing due to lost to follow-up. A sampling based approach was used to identify outcome in a subsample of lost patients and to obtain a valid estimate of connection to care. A valid estimator for cumulative incidence of events accounting for competing risks under a general sampling design from an infinite target population is derived.

  17. Semi-Competing Risks Data Analysis: Accounting for Death as a Competing Risk When the Outcome of Interest is Non-Terminal

    PubMed Central

    Haneuse, Sebastien; Lee, Kyu Ha

    2016-01-01

    Hospital readmission is a key marker of quality of health care. Notwithstanding its widespread use, however, it remains controversial in part because statistical methods used to analyze readmission, primarily logistic regression and related models, may not appropriately account for patients who die prior to experiencing a readmission event within the timeframe of interest. Towards resolving this, we describe and illustrate the semi-competing risks framework, which refers to the general setting where scientific interest lies with some non-terminal event (e.g. readmission), the occurrence of which is subject to a terminal event (e.g. death). Although a number of statistical analysis methods have been proposed for semi-competing risks data, we describe in detail the use of illness-death models primarily because of their relation to well-known methods for survival analysis and the availability of software. We also describe and consider in detail a number of existing approaches that could, in principle, be used to analyze semi-competing risks data including composite endpoint and competing risks analyses. Throughout we illustrate the ideas and methods using data on N=49,763 Medicare beneficiaries hospitalized between 2011–2013 with a principle discharge diagnosis of heart failure. PMID:27072677

  18. Competing risks models and time-dependent covariates

    PubMed Central

    Barnett, Adrian; Graves, Nick

    2008-01-01

    New statistical models for analysing survival data in an intensive care unit context have recently been developed. Two models that offer significant advantages over standard survival analyses are competing risks models and multistate models. Wolkewitz and colleagues used a competing risks model to examine survival times for nosocomial pneumonia and mortality. Their model was able to incorporate time-dependent covariates and so examine how risk factors that changed with time affected the chances of infection or death. We briefly explain how an alternative modelling technique (using logistic regression) can more fully exploit time-dependent covariates for this type of data. PMID:18423067

  19. Managing Competing Influences: Risk Acceptance in Operation Rolling Thunder

    DTIC Science & Technology

    2017-03-12

    Managing Competing Influences: Risk Acceptance in Operation Rolling Thunder A Monograph by Major Benjamin C. Williams US Air Force School of...REPORT TYPE Master’s Thesis 3. DATES COVERED (From - To) JUN 2016 – MAY 2017 4. TITLE AND SUBTITLE Managing Competing Influences: Risk Acceptance in...ANSI Std. Z39.18 ii Monograph Approval Page Name of Candidate: Major Benjamin C. Williams, USAF Monograph Title: Managing Competing Influences

  20. Epidemiology of competence: a scoping review to understand the risks and supports to competence of four health professions

    PubMed Central

    Glover Takahashi, Susan; Nayer, Marla

    2017-01-01

    Objectives This study examined the risks and supports to competence discussed in the literature related to occupational therapists, pharmacists, physical therapists and physicians, using epidemiology as a conceptual model. Design Articles from a scoping literature review, published from 1975 to 2014 inclusive, were included if they were about a risk or support to the professional or clinical competence of one of four health professions. Descriptive and regression analyses identified potential associations between risks and supports to competence and the location of study, type of health profession, competence life-cycle and the domain(s) of competence (organised around the CanMEDS framework). Results A total of 3572 abstracts were reviewed and 943 articles analysed. Most focused on physicians (n=810, 86.0%) and ‘practice’ (n=642, 68.0%). Fewer articles discussed risks to competence (n=418, 44.3%) than supports (n=750, 79.5%). The top four risks, each discussed in over 15% of articles, were: transitions in practice, being an international graduate, lack of clinical exposure/experience (ie, insufficient volume of procedures or patients) and age. The top two supports (over 35%) were continuing education participation and educational information/programme features. About 60% of all the articles discussed medical expert and about 25% applied to all roles. Articles focusing on residents had a greater probability of reporting on risks. Conclusions Articles about physicians were dominant. The majority of articles were written in the last decade and more discussed supports than risks to competence. An epidemiology-based conceptual model offers a helpful organising framework for exploring and explaining the competence of health professions. PMID:28864686

  1. Identifying Factors Associated with Risk Assessment Competencies of Public Health Emergency Responders.

    PubMed

    Hao, Jiejing; Ren, Jiaojiao; Wu, Qunhong; Hao, Yanhua; Sun, Hong; Ning, Ning; Ding, Ding

    2017-06-04

    This study aimed to better understand the current situation of risk assessment and identify the factors associated with competence of emergency responders in public health risk assessment. The participants were selected by a multi-stage, stratified cluster sampling method in Heilongjiang Centers for Disease Control and Prevention (CDC). The questionnaires that measured their perceptions on risk assessment competences were administered through the face-to-face survey. A final sample of 1889 staff was obtained. Of this sample, 78.6% of respondents rated their own risk assessment competences as "relatively low", contrasting with 21.4% rated as "relatively high". Most of the respondents (62.7%) did not participate in any risk assessment work. Only 13.7% and 42.7% of respondents reported participating in risk assessment training and were familiar with risk assessment tools. There existed statistical significance between risk assessment-related characteristics of respondents and their self-rated competences scores. Financial support from the government and administrative attention were regarded as the important factors contributing to risk assessment competences of CDC responders. Higher attention should be given to risk assessment training and enhancing the availability of surveillance data. Continuous efforts should be made to remove the financial and technical obstacles to improve the competences of risk assessment for public health emergency responders.

  2. Identifying Factors Associated with Risk Assessment Competencies of Public Health Emergency Responders

    PubMed Central

    Hao, Jiejing; Ren, Jiaojiao; Wu, Qunhong; Hao, Yanhua; Sun, Hong; Ning, Ning; Ding, Ding

    2017-01-01

    This study aimed to better understand the current situation of risk assessment and identify the factors associated with competence of emergency responders in public health risk assessment. The participants were selected by a multi-stage, stratified cluster sampling method in Heilongjiang Centers for Disease Control and Prevention (CDC). The questionnaires that measured their perceptions on risk assessment competences were administered through the face-to-face survey. A final sample of 1889 staff was obtained. Of this sample, 78.6% of respondents rated their own risk assessment competences as “relatively low”, contrasting with 21.4% rated as “relatively high”. Most of the respondents (62.7%) did not participate in any risk assessment work. Only 13.7% and 42.7% of respondents reported participating in risk assessment training and were familiar with risk assessment tools. There existed statistical significance between risk assessment-related characteristics of respondents and their self-rated competences scores. Financial support from the government and administrative attention were regarded as the important factors contributing to risk assessment competences of CDC responders. Higher attention should be given to risk assessment training and enhancing the availability of surveillance data. Continuous efforts should be made to remove the financial and technical obstacles to improve the competences of risk assessment for public health emergency responders. PMID:28587226

  3. 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.

  4. Family cumulative risk and at-risk kindergarteners' social competence: the mediating role of parent representations of the attachment relationship.

    PubMed

    Sparks, Lauren A; Trentacosta, Christopher J; Owusu, Erika; McLear, Caitlin; Smith-Darden, Joanne

    2018-08-01

    Secure attachment relationships have been linked to social competence in at-risk children. In the current study, we examined the role of parent secure base scripts in predicting at-risk kindergarteners' social competence. Parent representations of secure attachment were hypothesized to mediate the relationship between lower family cumulative risk and children's social competence. Participants included 106 kindergarteners and their primary caregivers recruited from three urban charter schools serving low-income families as a part of a longitudinal study. Lower levels of cumulative risk predicted greater secure attachment representations in parents, and scores on the secure base script assessment predicted children's social competence. An indirect relationship between lower cumulative risk and kindergarteners' social competence via parent secure base script scores was also supported. Parent script-based representations of the attachment relationship appear to be an important link between lower levels of cumulative risk and low-income kindergarteners' social competence. Implications of these findings for future interventions are discussed.

  5. 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

  6. A review and critique of some models used in competing risk analysis.

    PubMed

    Gail, M

    1975-03-01

    We have introduced a notation which allows one to define competing risk models easily and to examine underlying assumptions. We have treated the actuarial model for competing risk in detail, comparing it with other models and giving useful variance formulae both for the case when times of death are available and for the case when they are not. The generality of these methods is illustrated by an example treating two dependent competing risks.

  7. [Application of Competing Risks Model in Predicting Smoking Relapse Following Ischemic Stroke].

    PubMed

    Hou, Li-Sha; Li, Ji-Jie; Du, Xu-Dong; Yan, Pei-Jing; Zhu, Cai-Rong

    2017-07-01

    To determine factors associated with smoking relapse in men who survived from their first stroke. Data were collected through face to face interviews with stroke patients in the hospital, and then repeated every three months via telephone over the period from 2010 to 2014. Kaplan-Meier method and competing risk model were adopted to estimate and predict smoking relapse rates. The Kaplan-Meier method estimated a higher relapse rate than the competing risk model. The four-year relapse rate was 43.1% after adjustment of competing risk. Exposure to environmental tobacco smoking outside of home and workplace (such as bars and restaurants) ( P =0.01), single ( P <0.01), and prior history of smoking at least 20 cigarettes per day ( P =0.02) were significant predictors of smoking relapse. When competing risks exist, competing risks model should be used in data analyses. Smoking interventions should give priorities to those without a spouse and those with a heavy smoking history. Smoking ban in public settings can reduce smoking relapse in stroke patients.

  8. Risky-Play at School. Facilitating Risk Perception and Competence in Young Children

    ERIC Educational Resources Information Center

    Lavrysen, Ann; Bertrands, Els; Leyssen, Leene; Smets, Lieve; Vanderspikken, Anja; De Graef, Peter

    2017-01-01

    Recent research indicates that risk competence and perception can be improved through the learning environment. The project "Riscki" examined how risk perception and risk competence in young children between three and eight years of age can be observed and measured within the classroom and school context. An intensive package of…

  9. Accounting for individualized competing mortality risks in estimating postmenopausal breast cancer risk.

    PubMed

    Schonberg, Mara A; Li, Vicky W; Eliassen, A Heather; Davis, Roger B; LaCroix, Andrea Z; McCarthy, Ellen P; Rosner, Bernard A; Chlebowski, Rowan T; Hankinson, Susan E; Marcantonio, Edward R; Ngo, Long H

    2016-12-01

    Accurate risk assessment is necessary for decision-making around breast cancer prevention. We aimed to develop a breast cancer prediction model for postmenopausal women that would take into account their individualized competing risk of non-breast cancer death. We included 73,066 women who completed the 2004 Nurses' Health Study (NHS) questionnaire (all ≥57 years) and followed participants until May 2014. We considered 17 breast cancer risk factors (health behaviors, demographics, family history, reproductive factors) and 7 risk factors for non-breast cancer death (comorbidities, functional dependency) and mammography use. We used competing risk regression to identify factors independently associated with breast cancer. We validated the final model by examining calibration (expected-to-observed ratio of breast cancer incidence, E/O) and discrimination (c-statistic) using 74,887 subjects from the Women's Health Initiative Extension Study (WHI-ES; all were ≥55 years and followed for 5 years). Within 5 years, 1.8 % of NHS participants were diagnosed with breast cancer (vs. 2.0 % in WHI-ES, p = 0.02), and 6.6 % experienced non-breast cancer death (vs. 5.2 % in WHI-ES, p < 0.001). Using a model selection procedure which incorporated the Akaike Information Criterion, c-statistic, statistical significance, and clinical judgement, our final model included 9 breast cancer risk factors, 5 comorbidities, functional dependency, and mammography use. The model's c-statistic was 0.61 (95 % CI [0.60-0.63]) in NHS and 0.57 (0.55-0.58) in WHI-ES. On average, our model under predicted breast cancer in WHI-ES (E/O 0.92 [0.88-0.97]). We developed a novel prediction model that factors in postmenopausal women's individualized competing risks of non-breast cancer death when estimating breast cancer risk.

  10. Accounting for individualized competing mortality risks in estimating postmenopausal breast cancer risk

    PubMed Central

    Schonberg, Mara A.; Li, Vicky W.; Eliassen, A. Heather; Davis, Roger B.; LaCroix, Andrea Z.; McCarthy, Ellen P.; Rosner, Bernard A.; Chlebowski, Rowan T.; Hankinson, Susan E.; Marcantonio, Edward R.; Ngo, Long H.

    2016-01-01

    Purpose Accurate risk assessment is necessary for decision-making around breast cancer prevention. We aimed to develop a breast cancer prediction model for postmenopausal women that would take into account their individualized competing risk of non-breast cancer death. Methods We included 73,066 women who completed the 2004 Nurses’ Health Study (NHS) questionnaire (all ≥57 years) and followed participants until May 2014. We considered 17 breast cancer risk factors (health behaviors, demographics, family history, reproductive factors), 7 risk factors for non-breast cancer death (comorbidities, functional dependency), and mammography use. We used competing risk regression to identify factors independently associated with breast cancer. We validated the final model by examining calibration (expected-to-observed ratio of breast cancer incidence, E/O) and discrimination (c-statistic) using 74,887 subjects from the Women’s Health Initiative Extension Study (WHI-ES; all were ≥55 years and followed for 5 years). Results Within 5 years, 1.8% of NHS participants were diagnosed with breast cancer (vs. 2.0% in WHI-ES, p=0.02) and 6.6% experienced non-breast cancer death (vs. 5.2% in WHI-ES, p<0.001). Using a model selection procedure which incorporated the Akaike Information Criterion, c-statistic, statistical significance, and clinical judgement, our final model included 9 breast cancer risk factors, 5 comorbidities, functional dependency, and mammography use. The model’s c-statistic was 0.61 (95% CI [0.60–0.63]) in NHS and 0.57 (0.55–0.58) in WHI-ES. On average our model under predicted breast cancer in WHI-ES (E/O 0.92 [0.88–0.97]). Conclusions We developed a novel prediction model that factors in postmenopausal women’s individualized competing risks of non-breast cancer death when estimating breast cancer risk. PMID:27770283

  11. Calibration plots for risk prediction models in the presence of competing risks.

    PubMed

    Gerds, Thomas A; Andersen, Per K; Kattan, Michael W

    2014-08-15

    A predicted risk of 17% can be called reliable if it can be expected that the event will occur to about 17 of 100 patients who all received a predicted risk of 17%. Statistical models can predict the absolute risk of an event such as cardiovascular death in the presence of competing risks such as death due to other causes. For personalized medicine and patient counseling, it is necessary to check that the model is calibrated in the sense that it provides reliable predictions for all subjects. There are three often encountered practical problems when the aim is to display or test if a risk prediction model is well calibrated. The first is lack of independent validation data, the second is right censoring, and the third is that when the risk scale is continuous, the estimation problem is as difficult as density estimation. To deal with these problems, we propose to estimate calibration curves for competing risks models based on jackknife pseudo-values that are combined with a nearest neighborhood smoother and a cross-validation approach to deal with all three problems. Copyright © 2014 John Wiley & Sons, Ltd.

  12. 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. © 2016 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.

  13. Risks, risk assessment and risk competence in toxicology.

    PubMed

    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.

  14. Accounting for competing risks in randomized controlled trials: a review and recommendations for improvement.

    PubMed

    Austin, Peter C; Fine, Jason P

    2017-04-15

    In studies with survival or time-to-event outcomes, a competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. Specialized statistical methods must be used to analyze survival data in the presence of competing risks. We conducted a review of randomized controlled trials with survival outcomes that were published in high-impact general medical journals. Of 40 studies that we identified, 31 (77.5%) were potentially susceptible to competing risks. However, in the majority of these studies, the potential presence of competing risks was not accounted for in the statistical analyses that were described. Of the 31 studies potentially susceptible to competing risks, 24 (77.4%) reported the results of a Kaplan-Meier survival analysis, while only five (16.1%) reported using cumulative incidence functions to estimate the incidence of the outcome over time in the presence of competing risks. The former approach will tend to result in an overestimate of the incidence of the outcome over time, while the latter approach will result in unbiased estimation of the incidence of the primary outcome over time. We provide recommendations on the analysis and reporting of randomized controlled trials with survival outcomes in the presence of competing risks. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.

  15. Accounting for competing risks in randomized controlled trials: a review and recommendations for improvement

    PubMed Central

    Fine, Jason P.

    2017-01-01

    In studies with survival or time‐to‐event outcomes, a competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. Specialized statistical methods must be used to analyze survival data in the presence of competing risks. We conducted a review of randomized controlled trials with survival outcomes that were published in high‐impact general medical journals. Of 40 studies that we identified, 31 (77.5%) were potentially susceptible to competing risks. However, in the majority of these studies, the potential presence of competing risks was not accounted for in the statistical analyses that were described. Of the 31 studies potentially susceptible to competing risks, 24 (77.4%) reported the results of a Kaplan–Meier survival analysis, while only five (16.1%) reported using cumulative incidence functions to estimate the incidence of the outcome over time in the presence of competing risks. The former approach will tend to result in an overestimate of the incidence of the outcome over time, while the latter approach will result in unbiased estimation of the incidence of the primary outcome over time. We provide recommendations on the analysis and reporting of randomized controlled trials with survival outcomes in the presence of competing risks. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd. PMID:28102550

  16. 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

  17. High- and Low-Risk Characteristics of Youth: The Five Cs of Competency.

    ERIC Educational Resources Information Center

    McWhirter, J. Jeffries; And Others

    1994-01-01

    Identifies and discusses five basic skill strengths or skill deficits that mark critical difference between low-risk and high-risk youth. The "Five Cs of Competency" described include critical school competencies, concept of self and self-esteem, communication skills, coping ability, and control. Contends that these characteristics discriminate…

  18. 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.

  19. Linear and nonlinear variable selection in competing risks data.

    PubMed

    Ren, Xiaowei; Li, Shanshan; Shen, Changyu; Yu, Zhangsheng

    2018-06-15

    Subdistribution hazard model for competing risks data has been applied extensively in clinical researches. Variable selection methods of linear effects for competing risks data have been studied in the past decade. There is no existing work on selection of potential nonlinear effects for subdistribution hazard model. We propose a two-stage procedure to select the linear and nonlinear covariate(s) simultaneously and estimate the selected covariate effect(s). We use spectral decomposition approach to distinguish the linear and nonlinear parts of each covariate and adaptive LASSO to select each of the 2 components. Extensive numerical studies are conducted to demonstrate that the proposed procedure can achieve good selection accuracy in the first stage and small estimation biases in the second stage. The proposed method is applied to analyze a cardiovascular disease data set with competing death causes. Copyright © 2018 John Wiley & Sons, Ltd.

  20. 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…

  1. Score tests for independence in semiparametric competing risks models.

    PubMed

    Saïd, Mériem; Ghazzali, Nadia; Rivest, Louis-Paul

    2009-12-01

    A popular model for competing risks postulates the existence of a latent unobserved failure time for each risk. Assuming that these underlying failure times are independent is attractive since it allows standard statistical tools for right-censored lifetime data to be used in the analysis. This paper proposes simple independence score tests for the validity of this assumption when the individual risks are modeled using semiparametric proportional hazards regressions. It assumes that covariates are available, making the model identifiable. The score tests are derived for alternatives that specify that copulas are responsible for a possible dependency between the competing risks. The test statistics are constructed by adding to the partial likelihoods for the individual risks an explanatory variable for the dependency between the risks. A variance estimator is derived by writing the score function and the Fisher information matrix for the marginal models as stochastic integrals. Pitman efficiencies are used to compare test statistics. A simulation study and a numerical example illustrate the methodology proposed in this paper.

  2. Risk factors for deep vein thrombosis and pulmonary embolism after traumatic injury: A competing risks analysis.

    PubMed

    Van Gent, Jan-Michael; Calvo, Richard Yee; Zander, Ashley L; Olson, Erik J; Sise, C Beth; Sise, Michael J; Shackford, Steven R

    2017-12-01

    Venous thromboembolism, including deep vein thrombosis (DVT) and pulmonary embolism (PE), is typically reported as a composite measure of the quality of trauma center care. Given that recent data suggesting postinjury DVT and PE are distinct clinical processes, a better understanding may result from analyzing them as independent, competing events. Using competing risks analysis, we evaluated our hypothesis that the risk factors and timing of postinjury DVT and PE are different. We examined all adult trauma patients admitted to our Level I trauma center from July 2006 to December 2011 who received at least one surveillance duplex ultrasound of the lower extremities and who were at high risk or greater for DVT. Outcomes included DVT and PE events, and time-to-event from admission. We used competing risks analysis to evaluate risk factors for DVT while accounting for PE as a competing event, and vice versa. Of 2,370 patients, 265 (11.2%) had at least one venous thromboembolism event, 235 DVT only, 19 PE only, 11 DVT and PE. Within 2 days of admission, 38% of DVT cases had occurred compared with 26% of PE. Competing risks modeling of DVT as primary event identified older age, severe injury (Injury Severity Score, ≥ 15), mechanical ventilation longer than 4 days, active cancer, history of DVT or PE, major venous repair, male sex, and prophylactic enoxaparin and prophylactic heparin as associated risk factors. Modeling of PE as the primary event showed younger age, nonsevere injury (Injury Severity Score, < 15), central line placement, and prophylactic heparin as relevant factors. The risk factors for PE and DVT after injury were different, suggesting that they are clinically distinct events that merit independent consideration. Many DVT events occurred early despite prophylaxis, bringing into question the preventability of postinjury DVT. We recommend trauma center quality reporting program measures be revised to account for DVT and PE as unique events. Epidemiologic

  3. Competing collinear and noncollinear interactions in chirped quasi-phase-matched optical parametric amplifiers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, M. M.

    Chirped quasi-phase-matched optical parametric amplifiers (chirped QPM OPAs) are investigated experimentally. The measured collinear gain is constant over a broad bandwidth, which makes these devices attractive candidates for use in femtosecond amplifier systems. The experiment also shows that chirped QPM OPAs support noncollinear gain-guided modes. These modes can dominate the desired collinear gain and generate intense parametric fluorescence. Finally, design guidelines to mitigate these parasitic processes are discussed.

  4. Risk Competence in Dealing With Alcohol and Other Drugs in Adolescence.

    PubMed

    Nagy, Ede; Verres, Rolf; Grevenstein, Dennis

    2017-12-06

    Adolescence is a critical phase for the development substance use patterns. We propose that individual competence in dealing with psychoactive substances is crucial for the development of healthy substance use behavior and prevention of substance misuse or addiction. We present a new concept of health related skills in dealing with alcohol and other drugs in adolescence, its operationalization and validation. Our conception of risk competence (RICO) consists of the four major factors being Reflective, Informed, Self-Controlled and Life-Oriented, and their sub-facets. Based on a sample of N = 753 adolescents we used classical test theory as well as item response theory to create a new measure of RICO. Validity was investigated in a new sample of N = 229 with regard to substance use, risk perception, and measures of personality (Big Five, sense of coherence, general self-efficacy). RICO contains 7 scales with 28 items that measure independent aspects of risk competence. Cross-sectional criterion validity for most of the scales could be shown. Conclusions/Importance: The new RICO scales are a valid measure of different aspects of risk competence in dealing with psychoactive substances. The questionnaire can be used in general research settings, but may also be applied to assess the effects of interventions.

  5. Inverse probability of treatment-weighted competing risks analysis: an application on long-term risk of urinary adverse events after prostate cancer treatments.

    PubMed

    Bolch, Charlotte A; Chu, Haitao; Jarosek, Stephanie; Cole, Stephen R; Elliott, Sean; Virnig, Beth

    2017-07-10

    To illustrate the 10-year risks of urinary adverse events (UAEs) among men diagnosed with prostate cancer and treated with different types of therapy, accounting for the competing risk of death. Prostate cancer is the second most common malignancy among adult males in the United States. Few studies have reported the long-term post-treatment risk of UAEs and those that have, have not appropriately accounted for competing deaths. This paper conducts an inverse probability of treatment (IPT) weighted competing risks analysis to estimate the effects of different prostate cancer treatments on the risk of UAE, using a matched-cohort of prostate cancer/non-cancer control patients from the Surveillance, Epidemiology and End Results (SEER) Medicare database. Study dataset included men age 66 years or older that are 83% white and had a median follow-up time of 4.14 years. Patients that underwent combination radical prostatectomy and external beam radiotherapy experienced the highest risk of UAE (IPT-weighted competing risks: HR 3.65 with 95% CI (3.28, 4.07); 10-yr. cumulative incidence = 36.5%). Findings suggest that IPT-weighted competing risks analysis provides an accurate estimator of the cumulative incidence of UAE taking into account the competing deaths as well as measured confounding bias.

  6. 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

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

    PubMed

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

    2013-02-01

    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.

  8. Criteria for use of composite end points for competing risks-a systematic survey of the literature with recommendations.

    PubMed

    Manja, Veena; AlBashir, Siwar; Guyatt, Gordon

    2017-02-01

    Composite end points are frequently used in reports of clinical trials. One rationale for the use of composite end points is to account for competing risks. In the presence of competing risks, the event rate of a specific event depends on the rates of other competing events. One proposed solution is to include all important competing events in one composite end point. Clinical trialists require guidance regarding when this approach is appropriate. To identify publications describing criteria for use of composite end points for competing risk and to offer guidance regarding when a composite end point is appropriate on the basis of competing risks. We searched MEDLINE, CINAHL, EMBASE, The Cochrane's Central & Systematic Review databases including the Health Technology Assessment database, and the Cochrane's Methodology register from inception to April 2015, and candidate textbooks, to identify all articles providing guidance on this issue. Eligible publications explicitly addressed the issue of a composite outcome to address competing risks. Two reviewers independently screened the titles and abstracts for full-text review; independently reviewed full-text publications; and abstracted specific criteria authors offered for use of composite end points to address competing risks. Of 63,645 titles and abstracts, 166 proved potentially relevant of which 43 publications were included in the final review. Most publications note competing risks as a reason for using composite end points without further elaboration. None of the articles or textbook chapters provide specific criteria for use of composite end points for competing risk. Some advocate using composite end points to avoid bias due to competing risks and others suggest that composite end points seldom or never be used for this purpose. We recommend using composite end points for competing risks only if the competing risk is plausible and if it occurs with sufficiently high frequency to influence the interpretation

  9. 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.

  10. Population-based absolute risk estimation with survey data

    PubMed Central

    Kovalchik, Stephanie A.; Pfeiffer, Ruth M.

    2013-01-01

    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

  11. Competing risks to breast cancer mortality in Catalonia

    PubMed Central

    Vilaprinyo, Ester; Gispert, Rosa; Martínez-Alonso, Montserrat; Carles, Misericòrdia; Pla, Roger; Espinàs, Josep-Alfons; Rué, Montserrat

    2008-01-01

    Background Breast cancer mortality has experienced important changes over the last century. Breast cancer occurs in the presence of other competing risks which can influence breast cancer incidence and mortality trends. The aim of the present work is: 1) to assess the impact of breast cancer deaths among mortality from all causes in Catalonia (Spain), by age and birth cohort and 2) to estimate the risk of death from other causes than breast cancer, one of the inputs needed to model breast cancer mortality reduction due to screening or therapeutic interventions. Methods The multi-decrement life table methodology was used. First, all-cause mortality probabilities were obtained by age and cohort. Then mortality probability for breast cancer was subtracted from the all-cause mortality probabilities to obtain cohort life tables for causes other than breast cancer. These life tables, on one hand, provide an estimate of the risk of dying from competing risks, and on the other hand, permit to assess the impact of breast cancer deaths on all-cause mortality using the ratio of the probability of death for causes other than breast cancer by the all-cause probability of death. Results There was an increasing impact of breast cancer on mortality in the first part of the 20th century, with a peak for cohorts born in 1945–54 in the 40–49 age groups (for which approximately 24% of mortality was due to breast cancer). Even though for cohorts born after 1955 there was only information for women under 50, it is also important to note that the impact of breast cancer on all-cause mortality decreased for those cohorts. Conclusion We have quantified the effect of removing breast cancer mortality in different age groups and birth cohorts. Our results are consistent with US findings. We also have obtained an estimate of the risk of dying from competing-causes mortality, which will be used in the assessment of the effect of mammography screening on breast cancer mortality in Catalonia

  12. Competing risk analysis of mortality in prostate cancer treated with radical prostatectomy.

    PubMed

    Ruiz-Cerdá, J L; Soto-Poveda, A; Luján-Marco, S; Loras-Monfort, A; Trassierra-Villa, M; Rogel-Bertó, R; Boronat-Tormo, F

    To determine the risk of cancer-specific mortality (CSM) versus the competing risk of mortality by other causes (MOC) in patients with localised prostate cancer (LPC) treated with radical prostatectomy (RP). An observational cohort study of 982 patients with LPC treated with RP selected from our department's PC registry database. A competing risk analysis was performed, calculating the probability of CSM in the presence of the competing risk of MOC. Cumulative incidence curves were constructed, and point estimates were performed at 5, 10 and 15 years. The analysis was stratified by age (≤65 vs. >65 years) and risk group: low (Gleason score ≤6 and pT2abc); intermediate (Gleason score of 7 and pT2abc) and high (Gleason score of 8-10 or pT3ab). With a median follow-up of 60 months, the overall probability of dying from PC was 3.5%, and the probability of dying from other causes was 9%. A competing effect for MOC was observed. The risk of MOC was almost 3 times greater than that of CSM. This effect remained for all risk groups, although its magnitude decreased progressively according to the risk group level. At 10 years, CSM was only 0%, 1% and 2% for the low, intermediate and high-risk groups, respectively, while the likelihood of MOC was 4%, 4% and 10%, respectively. The mortality risk was shown after 10years of follow-up and was higher for other causes not attributable to PC and for patients older than 65years. The benefit of RP might be overestimated, given that the risk of MOC is greater than that of CSM, regardless of the age group and risk group, especially after 10years of follow-up. The only parameter that varied was the magnitude of the CSM/MOC ratio. This information could help in choosing the active treatment for patients with LPC and short life expectancies. Copyright © 2016 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  13. 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…

  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. Heterogeneity in risk of prostate cancer: A Swedish population-based cohort study of competing risks and type 2 diabetes mellitus.

    PubMed

    Häggström, Christel; Van Hemelrijck, Mieke; Garmo, Hans; Robinson, David; Stattin, Pär; Rowley, Mark; Coolen, Anthony C C; Holmberg, Lars

    2018-05-09

    Most previous studies of prostate cancer have not taken into account that men in the studied populations are also at risk of competing event, and that these men may have different susceptibility to prostate cancer risk. The aim of this study was to investigate heterogeneity in risk of prostate cancer, using a recently developed latent class regression method for competing risks. We further aimed to elucidate the association between type 2 diabetes mellitus (T2DM) and prostate cancer risk, and to compare the results with conventional methods for survival analysis. We analysed the risk of prostate cancer in 126,482 men from the comparison cohort of the Prostate Cancer Data base Sweden (PCBaSe) 3.0. During a mean follow-up of 6 years 6,036 men were diagnosed with prostate cancer and 22,393 men died. We detected heterogeneity in risk of prostate cancer with two distinct latent classes in the study population. The smaller class included 9% of the study population in which men had a higher risk of prostate cancer and the risk was stronger associated with class membership than any of the covariates included in the study. Moreover, we found no association between T2DM and risk of prostate cancer after removal of the effect of informative censoring due to competing risks. The recently developed latent class for competing risks method could be used to provide new insights in precision medicine with the target to classify individuals regarding different susceptibility to a particular disease, reaction to a risk factor or response to treatment. This article is protected by copyright. All rights reserved. © 2018 UICC.

  16. Optimising import risk mitigation: anticipating the unintended consequences and competing risks of informal trade.

    PubMed

    Hueston, W; Travis, D; van Klink, E

    2011-04-01

    The effectiveness of risk mitigation may be compromised by informal trade, including illegal activities, parallel markets and extra-legal activities. While no regulatory system is 100% effective in eliminating the risk of disease transmission through animal and animal product trade, extreme risk aversion in formal import health regulations may increase informal trade, with the unintended consequence of creating additional risks outside regulatory purview. Optimal risk mitigation on a national scale requires scientifically sound yet flexible mitigation strategies that can address the competing risks of formal and informal trade. More robust risk analysis and creative engagement of nontraditional partners provide avenues for addressing informal trade.

  17. A proportional hazards regression model for the subdistribution with right-censored and left-truncated competing risks data

    PubMed Central

    Zhang, Xu; Zhang, Mei-Jie; Fine, Jason

    2012-01-01

    With competing risks failure time data, one often needs to assess the covariate effects on the cumulative incidence probabilities. Fine and Gray proposed a proportional hazards regression model to directly model the subdistribution of a competing risk. They developed the estimating procedure for right-censored competing risks data, based on the inverse probability of censoring weighting. Right-censored and left-truncated competing risks data sometimes occur in biomedical researches. In this paper, we study the proportional hazards regression model for the subdistribution of a competing risk with right-censored and left-truncated data. We adopt a new weighting technique to estimate the parameters in this model. We have derived the large sample properties of the proposed estimators. To illustrate the application of the new method, we analyze the failure time data for children with acute leukemia. In this example, the failure times for children who had bone marrow transplants were left truncated. PMID:21557288

  18. 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.

  19. Human disease mortality kinetics are explored through a chain model embodying principles of extreme value theory and competing risks.

    PubMed

    Juckett, D A; Rosenberg, B

    1992-04-21

    The distributions for human disease-specific mortality exhibit two striking characteristics: survivorship curves that intersect near the longevity limit; and, the clustering of best-fitting Weibull shape parameter values into groups centered on integers. Correspondingly, we have hypothesized that the distribution intersections result from either competitive processes or population partitioning and the integral clustering in the shape parameter results from the occurrence of a small number of rare, rate-limiting events in disease progression. In this report we initiate a theoretical examination of these questions by exploring serial chain model dynamics and parameteric competing risks theory. The links in our chain models are composed of more than one bond, where the number of bonds in a link are denoted the link size and are the number of events necessary to break the link and, hence, the chain. We explored chains with all links of the same size or with segments of the chain composed of different size links (competition). Simulations showed that chain breakage dynamics depended on the weakest-link principle and followed kinetics of extreme-values which were very similar to human mortality kinetics. In particular, failure distributions for simple chains were Weibull-type extreme-value distributions with shape parameter values that were identifiable with the integral link size in the limit of infinite chain length. Furthermore, for chains composed of several segments of differing link size, the survival distributions for the various segments converged at a point in the S(t) tails indistinguishable from human data. This was also predicted by parameteric competing risks theory using Weibull underlying distributions. In both the competitive chain simulations and the parametric competing risks theory, however, the shape values for the intersecting distributions deviated from the integer values typical of human data. We conclude that rare events can be the source of

  20. 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.

  1. Analysis and design of randomised clinical trials involving competing risks endpoints.

    PubMed

    Tai, Bee-Choo; Wee, Joseph; Machin, David

    2011-05-19

    In randomised clinical trials involving time-to-event outcomes, the failures concerned may be events of an entirely different nature and as such define a classical competing risks framework. In designing and analysing clinical trials involving such endpoints, it is important to account for the competing events, and evaluate how each contributes to the overall failure. An appropriate choice of statistical model is important for adequate determination of sample size. We describe how competing events may be summarised in such trials using cumulative incidence functions and Gray's test. The statistical modelling of competing events using proportional cause-specific and subdistribution hazard functions, and the corresponding procedures for sample size estimation are outlined. These are illustrated using data from a randomised clinical trial (SQNP01) of patients with advanced (non-metastatic) nasopharyngeal cancer. In this trial, treatment has no effect on the competing event of loco-regional recurrence. Thus the effects of treatment on the hazard of distant metastasis were similar via both the cause-specific (unadjusted csHR = 0.43, 95% CI 0.25 - 0.72) and subdistribution (unadjusted subHR 0.43; 95% CI 0.25 - 0.76) hazard analyses, in favour of concurrent chemo-radiotherapy followed by adjuvant chemotherapy. Adjusting for nodal status and tumour size did not alter the results. The results of the logrank test (p = 0.002) comparing the cause-specific hazards and the Gray's test (p = 0.003) comparing the cumulative incidences also led to the same conclusion. However, the subdistribution hazard analysis requires many more subjects than the cause-specific hazard analysis to detect the same magnitude of effect. The cause-specific hazard analysis is appropriate for analysing competing risks outcomes when treatment has no effect on the cause-specific hazard of the competing event. It requires fewer subjects than the subdistribution hazard analysis for a similar effect size

  2. Nonparametric analysis of bivariate gap time with competing risks.

    PubMed

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

    2016-09-01

    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. © 2016, The International Biometric Society.

  3. Development and evaluation of the "BRISK Scale," a brief observational measure of risk communication competence.

    PubMed

    Han, Paul K J; Joekes, Katherine; Mills, Greg; Gutheil, Caitlin; Smith, Kahsi; Cochran, Nancy E; Elwyn, Glyn

    2016-12-01

    To develop and evaluate a brief observational measure of clinical risk communication competence. A 4-item checklist-type measure, the BRISK (Brief Risk Information Skill) Scale, was developed by selecting and refining items from a more comprehensive measure of clinical risk communication competence. Six volunteer raters received brief training on the measure and then used the BRISK Scale to evaluate 52 video-recorded encounters between 2nd-year medical students and standardized patients conducted as part of an Observed Structured Clinical Examination (OSCE) involving a risk communication task. Internal consistency reliability, inter-rater reliability, and criterion validity were assessed. Raters reported no difficulties using the BRISK Scale; scores across all raters and subjects ranged from 0 to 16 with a mean score of 6.49 (SD=3.17). The BRISK Scale showed good internal consistency reliability (α=0.64), and inter-rater reliability at the scale level (Intraclass Correlation Coefficient (ICC)=0.79 for consistency, and 0.75 for absolute agreement) and individual-item level (ICC range: 0.62-.91). Novice raters' BRISK Scale scores were highly correlated (r=0.84, p<0.01) with expert raters' scores on the Risk Communication Content measure, a more comprehensive measure of risk communication competence. The BRISK Scale is a promising new brief observational measure of clinical risk communication competence. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. A method for evaluating competency in assessment and management of suicide risk.

    PubMed

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

    2012-01-01

    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 examination (OSCE). The authors developed the CAI-S on the basis of the literature on suicide risk-assessment and management, and consultation with faculty focus groups from three sites in a large academic psychiatry department. The CAI-S structures faculty ratings regarding interviewing and data collection, case formulation and presentation, treatment-planning, and documentation. To evaluate the CAI-S, 31 faculty members used it to rate the performance of 31 learners (26 psychiatric residents and 5 clinical psychology interns) who participated in an OSCE. After interviewing a standardized patient, learners presented their risk-assessment findings and treatment plans. Faculty used the CAI-S to structure feedback to the learners. In a subsidiary study of interrater reliability, six faculty members rated video-recorded suicide risk-assessments. The CAI-S showed good internal consistency, reliability, and interrater reliability. Concurrent validity was supported by the finding that CAI-S ratings were higher for senior learners than junior learners, and were higher for learners with more clinical experience with suicidal patients than learners with less clinical experience. Faculty and learners rated the method as helpful for structuring feedback and supervision. The findings support the usefulness of the CAI-S for evaluating competency in suicide risk-assessment and management.

  5. Impact of Competing Risk of Mortality on Association of Weight Loss with Risk of Central Body Fractures in Older Men: A Prospective Cohort Study

    PubMed Central

    Ensrud, Kristine E.; Harrison, Stephanie L.; Cauley, Jane A.; Langsetmo, Lisa; Schousboe, John T.; Kado, Deborah M.; Gourlay, Margaret L.; Lyons, Jennifer G.; Fredman, Lisa; Napoli, Nicolas; Crandall, Carolyn J.; Lewis, Cora E.; Orwoll, Eric S.; Stefanick, Marcia L.; Cawthon, Peggy M.

    2017-01-01

    To determine the association of weight loss with risk of clinical fractures at the hip, spine and pelvis (central body fractures [CBF]) in older men with and without accounting for the competing risk of mortality, we used data from 4,523 men (mean age 77.5 years). Weight change between baseline and follow-up (mean 4.5 years between examinations) was categorized as moderate loss (loss ≥10%), mild loss (loss 5% to <10%), stable (<5% change) or gain (gain ≥5%). Participants were contacted every 4 months after the follow-up examination to ascertain vital status (deaths verified by death certificates) and ask about fractures (confirmed by radiographic reports). Absolute probability of CBF by weight change category was estimated using traditional Kaplan-Meier method and cumulative incidence function accounting for competing mortality risk. Risk of CBF by weight change category was determined using conventional Cox proportional hazards regression and subdistribution hazards models with death as a competing risk. During an average of 8 years, 337 men (7.5%) experienced CBF and 1,569 (34.7%) died before experiencing this outcome. Among men with moderate weight loss, CBF probability was 6.8% at 5 years and 16.9% at 10 years using Kaplan-Meier vs. 5.7% at 5 years and 10.2% at 10 years using a competing risk approach. Men with moderate weight loss compared with those with stable weight had a 1.6-fold higher adjusted risk of CBF (HR 1.59, 95% CI 1.06–2.38) using Cox models that was substantially attenuated in models accounting for competing mortality risk and no longer significant (subdistribution HR 1.16, 95% CI 0.77–1.75). Results were similar in analyses substituting hip fracture for CBF. Older men with weight loss who survive are at increased risk of CBF, including hip fracture. However, ignoring the competing mortality risk among men with weight loss substantially overestimates their longterm fracture probability and relative fracture risk. PMID:27739103

  6. The differential associations of preexisting conditions with trauma-related outcomes in the presence of competing risks.

    PubMed

    Calvo, Richard Yee; Lindsay, Suzanne P; Edland, Steven D; Macera, Caroline A; Wingard, Deborah L; Ohno-Machado, Lucila; Sise, Michael J

    2016-03-01

    Pre-existing chronic conditions (PECs) pose a unique problem for the care of aging trauma populations. However, the relationships between specific conditions and outcomes after injury are relatively unknown. Evaluation of trauma patients is further complicated by their discharge to care facilities, where mortality risk remains high. Traditional approaches for evaluating in-hospital mortality do not account for the discharge of at-risk patients, which constitutes a competing risk event to death. The objective of this study was to evaluate associations between 40 PECs and two clinical outcomes in the context of competing risks among older trauma patients. This retrospective study evaluated blunt-injured patients aged 55 years and older admitted to a level I trauma centre in 2006-2012. Outcomes were hospital length of stay (HLOS) and in-hospital mortality. Survivors were classified as discharges home or discharges to care facilities. Competing risks regression was used to evaluate each PEC with in-hospital mortality, accounting for discharges to care facilities as competing events. Competing risk estimates were compared to Cox model estimates, for which all survivors to discharge were non-events. Analyses were stratified using injury-based mortality risk at a 50% cutpoint (high versus low). Among 4653 patients, 176 died in-hospital, 3059 were discharged home, and 1418 were discharged to a care facility. Most patients (98%) were classified with a low mortality risk. Only haemophilia and coagulopathy were consistently associated with longer HLOS. In the low-risk subgroup, in-hospital mortality was most strongly associated with liver diseases, haemophilia, and coagulopathy. In the high-risk group, Parkinson's disease, depression, and cancers showed the strongest associations. Accounting for the competing event altered estimates for 12 of 19 significant conditions. Excess mortality among patients expected to survive their injuries may be attributable to complications

  7. A general framework for parametric survival analysis.

    PubMed

    Crowther, Michael J; Lambert, Paul C

    2014-12-30

    Parametric survival models are being increasingly used as an alternative to the Cox model in biomedical research. Through direct modelling of the baseline hazard function, we can gain greater understanding of the risk profile of patients over time, obtaining absolute measures of risk. Commonly used parametric survival models, such as the Weibull, make restrictive assumptions of the baseline hazard function, such as monotonicity, which is often violated in clinical datasets. In this article, we extend the general framework of parametric survival models proposed by Crowther and Lambert (Journal of Statistical Software 53:12, 2013), to incorporate relative survival, and robust and cluster robust standard errors. We describe the general framework through three applications to clinical datasets, in particular, illustrating the use of restricted cubic splines, modelled on the log hazard scale, to provide a highly flexible survival modelling framework. Through the use of restricted cubic splines, we can derive the cumulative hazard function analytically beyond the boundary knots, resulting in a combined analytic/numerical approach, which substantially improves the estimation process compared with only using numerical integration. User-friendly Stata software is provided, which significantly extends parametric survival models available in standard software. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Do Health Professionals Need Additional Competencies for Stratified Cancer Prevention Based on Genetic Risk Profiling?

    PubMed Central

    Chowdhury, Susmita; Henneman, Lidewij; Dent, Tom; Hall, Alison; Burton, Alice; Pharoah, Paul; Pashayan, Nora; Burton, Hilary

    2015-01-01

    There is growing evidence that inclusion of genetic information about known common susceptibility variants may enable population risk-stratification and personalized prevention for common diseases including cancer. This would require the inclusion of genetic testing as an integral part of individual risk assessment of an asymptomatic individual. Front line health professionals would be expected to interact with and assist asymptomatic individuals through the risk stratification process. In that case, additional knowledge and skills may be needed. Current guidelines and frameworks for genetic competencies of non-specialist health professionals place an emphasis on rare inherited genetic diseases. For common diseases, health professionals do use risk assessment tools but such tools currently do not assess genetic susceptibility of individuals. In this article, we compare the skills and knowledge needed by non-genetic health professionals, if risk-stratified prevention is implemented, with existing competence recommendations from the UK, USA and Europe, in order to assess the gaps in current competences. We found that health professionals would benefit from understanding the contribution of common genetic variations in disease risk, the rationale for a risk-stratified prevention pathway, and the implications of using genomic information in risk-assessment and risk management of asymptomatic individuals for common disease prevention. PMID:26068647

  9. 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

  10. Integrative genetic risk prediction using non-parametric empirical Bayes classification.

    PubMed

    Zhao, Sihai Dave

    2017-06-01

    Genetic risk prediction is an important component of individualized medicine, but prediction accuracies remain low for many complex diseases. A fundamental limitation is the sample sizes of the studies on which the prediction algorithms are trained. One way to increase the effective sample size is to integrate information from previously existing studies. However, it can be difficult to find existing data that examine the target disease of interest, especially if that disease is rare or poorly studied. Furthermore, individual-level genotype data from these auxiliary studies are typically difficult to obtain. This article proposes a new approach to integrative genetic risk prediction of complex diseases with binary phenotypes. It accommodates possible heterogeneity in the genetic etiologies of the target and auxiliary diseases using a tuning parameter-free non-parametric empirical Bayes procedure, and can be trained using only auxiliary summary statistics. Simulation studies show that the proposed method can provide superior predictive accuracy relative to non-integrative as well as integrative classifiers. The method is applied to a recent study of pediatric autoimmune diseases, where it substantially reduces prediction error for certain target/auxiliary disease combinations. The proposed method is implemented in the R package ssa. © 2016, The International Biometric Society.

  11. Predicting Time to Reflux of Children With Antenatal Hydronephrosis: A Competing Risks Approach.

    PubMed

    Nazemipour, Maryam; Kajbafzadeh, Abdol-Mohammad; Mohammad, Kazem; Rahimi Foroushani, Abbas; Mahmoudi, Mahmood

    2017-07-01

    The aim of this study was describing methodological aspects and applying a trivariate Weibull survival model using the competing risks concept to predict time to occurrence different types of reflux (unilateral (left, right) or bilateral) in children with antenatal hydronephrosis. Data from 333 children in Pediatric Urology Research Center of Children's Hospital Medical Center, affiliated with Tehran University of Medical Sciences was used. The effect of some demographic and clinical factors on child's reflux was studied. The assumption of independent between times of different types of reflux was evaluated. Of infants 80.5% were boy. The percentage of children experienced right, left and bilateral reflux or have been censored are 15.3%, 14.1%, 60.4% and 10.2% respectively. For the time of left reflux, variables, Week of diagnosis ANH, UC, UA, HUN, HN, APD_Right, Direction of ANH, CA19-9 baby, Urethra were significant. For the time of right reflux, variables, constipation, UC, UA, HUN, APD_Right, Direction and Severity of ANH, Bladder, and finally for the time of bilateral reflux, variables, Week of diagnosis ANH, Gender, UA, HUN, HN, APD_Left, Urethra, and Bladder were significant P<0.05. In the presence of competing risks, it is inappropriate to use the Kaplan-Meier method and standard Cox model which do not take competing risks into account. Trivariate Weibull survival model using competing risks not only is able to calculate the hazard rate of variables with different type of events but also it will be able to compare the hazard rate within the same type of event with different covariates.

  12. Partially linear mixed-effects joint models for skewed and missing longitudinal competing risks outcomes.

    PubMed

    Lu, Tao; Lu, Minggen; Wang, Min; Zhang, Jun; Dong, Guang-Hui; Xu, Yong

    2017-12-18

    Longitudinal competing risks data frequently arise in clinical studies. Skewness and missingness are commonly observed for these data in practice. However, most joint models do not account for these data features. In this article, we propose partially linear mixed-effects joint models to analyze skew longitudinal competing risks data with missingness. In particular, to account for skewness, we replace the commonly assumed symmetric distributions by asymmetric distribution for model errors. To deal with missingness, we employ an informative missing data model. The joint models that couple the partially linear mixed-effects model for the longitudinal process, the cause-specific proportional hazard model for competing risks process and missing data process are developed. To estimate the parameters in the joint models, we propose a fully Bayesian approach based on the joint likelihood. To illustrate the proposed model and method, we implement them to an AIDS clinical study. Some interesting findings are reported. We also conduct simulation studies to validate the proposed method.

  13. Prior health expenditures and risk sharing with insurers competing on quality.

    PubMed

    Marchand, Maurice; Sato, Motohiro; Schokkaert, Erik

    2003-01-01

    Insurers can exploit the heterogeneity within risk-adjustment classes to select the good risks because they have more information than the regulator on the expected expenditures of individual insurees. To counteract this cream skimming, mixed systems combining capitation and cost-based payments have been adopted that do not, however, generally use the past expenditures of insurees as a risk adjuster. In this article, two symmetric insurers compete for clients by differentiating the quality of service offered to them according to some private information about their risk. In our setting it is always welfare improving to use prior expenditures as a risk adjuster.

  14. Short pulse generation from a passively mode-locked fiber optical parametric oscillator with optical time-stretch.

    PubMed

    Qiu, Yi; Wei, Xiaoming; Du, Shuxin; Wong, Kenneth K Y; Tsia, Kevin K; Xu, Yiqing

    2018-04-16

    We propose a passively mode-locked fiber optical parametric oscillator assisted with optical time-stretch. Thanks to the lately developed optical time-stretch technique, the onset oscillating spectral components can be temporally dispersed across the pump envelope and further compete for the parametric gain with the other parts of onset oscillating sidebands within the pump envelope. By matching the amount of dispersion in optical time-stretch with the pulse width of the quasi-CW pump and oscillating one of the parametric sidebands inside the fiber cavity, we numerically show that the fiber parametric oscillator can be operated in a single pulse regime. By varying the amount of the intracavity dispersion, we further verify that the origin of this single pulse mode-locking regime is due to the optical pulse stretching and compression.

  15. Analyzing semi-competing risks data with missing cause of informative terminal event.

    PubMed

    Zhou, Renke; Zhu, Hong; Bondy, Melissa; Ning, Jing

    2017-02-28

    Cancer studies frequently yield multiple event times that correspond to landmarks in disease progression, including non-terminal events (i.e., cancer recurrence) and an informative terminal event (i.e., cancer-related death). Hence, we often observe semi-competing risks data. Work on such data has focused on scenarios in which the cause of the terminal event is known. However, in some circumstances, the information on cause for patients who experience the terminal event is missing; consequently, we are not able to differentiate an informative terminal event from a non-informative terminal event. In this article, we propose a method to handle missing data regarding the cause of an informative terminal event when analyzing the semi-competing risks data. We first consider the nonparametric estimation of the survival function for the terminal event time given missing cause-of-failure data via the expectation-maximization algorithm. We then develop an estimation method for semi-competing risks data with missing cause of the terminal event, under a pre-specified semiparametric copula model. We conduct simulation studies to investigate the performance of the proposed method. We illustrate our methodology using data from a study of early-stage breast cancer. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Impact of Competing Risk of Mortality on Association of Weight Loss With Risk of Central Body Fractures in Older Men: A Prospective Cohort Study.

    PubMed

    Ensrud, Kristine E; Harrison, Stephanie L; Cauley, Jane A; Langsetmo, Lisa; Schousboe, John T; Kado, Deborah M; Gourlay, Margaret L; Lyons, Jennifer G; Fredman, Lisa; Napoli, Nicolas; Crandall, Carolyn J; Lewis, Cora E; Orwoll, Eric S; Stefanick, Marcia L; Cawthon, Peggy M

    2017-03-01

    To determine the association of weight loss with risk of clinical fractures at the hip, spine, and pelvis (central body fractures [CBFs]) in older men with and without accounting for the competing risk of mortality, we used data from 4523 men (mean age 77.5 years). Weight change between baseline and follow-up (mean 4.5 years between examinations) was categorized as moderate loss (loss ≥10%), mild loss (loss 5% to <10%), stable (<5% change) or gain (gain ≥5%). Participants were contacted every 4 months after the follow-up examination to ascertain vital status (deaths verified by death certificates) and ask about fractures (confirmed by radiographic reports). Absolute probability of CBF by weight change category was estimated using traditional Kaplan-Meier method and cumulative incidence function accounting for competing mortality risk. Risk of CBF by weight change category was determined using conventional Cox proportional hazards regression and subdistribution hazards models with death as a competing risk. During an average of 8 years, 337 men (7.5%) experienced CBF and 1569 (34.7%) died before experiencing this outcome. Among men with moderate weight loss, CBF probability was 6.8% at 5 years and 16.9% at 10 years using Kaplan-Meier versus 5.7% at 5 years and 10.2% at 10 years using a competing risk approach. Men with moderate weight loss compared with those with stable weight had a 1.6-fold higher adjusted risk of CBF (HR 1.59; 95% CI, 1.06 to 2.38) using Cox models that was substantially attenuated in models accounting for competing mortality risk and no longer significant (subdistribution HR 1.16; 95% CI, 0.77 to 1.75). Results were similar in analyses substituting hip fracture for CBF. Older men with weight loss who survive are at increased risk of CBF, including hip fracture. However, ignoring the competing mortality risk among men with weight loss substantially overestimates their long-term fracture probability and relative fracture risk. © 2016 American

  17. Estimation and comparison of cumulative incidences of biliary self-expandable metallic stent dysfunction accounting for competing risks.

    PubMed

    Hamada, Tsuyoshi; Nakai, Yousuke; Isayama, Hiroyuki; Togawa, Osamu; Kogure, Hirofumi; Kawakubo, Kazumichi; Tsujino, Takeshi; Sasahira, Naoki; Hirano, Kenji; Yamamoto, Natsuyo; Ito, Yukiko; Sasaki, Takashi; Mizuno, Suguru; Toda, Nobuo; Tada, Minoru; Koike, Kazuhiko

    2014-03-01

    Self-expandable metallic stent (SEMS) placement is widely carried out for distal malignant biliary obstruction, and survival analysis is used to evaluate the cumulative incidences of SEMS dysfunction (e.g. the Kaplan-Meier [KM] method and the log-rank test). However, these statistical methods might be inappropriate in the presence of 'competing risks' (here, death without SEMS dysfunction), which affects the probability of experiencing the event of interest (SEMS dysfunction); that is, SEMS dysfunction can no longer be observed after death. A competing risk analysis has rarely been done in studies on SEMS. We introduced the concept of a competing risk analysis and illustrated its impact on the evaluation of SEMS outcomes using hypothetical and actual data. Our illustrative study included 476 consecutive patients who underwent SEMS placement for unresectable distal malignant biliary obstruction. A significant difference between cumulative incidences of SEMS dysfunction in male and female patients via theKM method (P = 0.044 by the log-rank test) disappeared after applying a competing risk analysis (P = 0.115 by Gray's test). In contrast, although cumulative incidences of SEMS dysfunction via the KM method were similar with and without chemotherapy (P = 0.647 by the log-rank test), cumulative incidence of SEMS dysfunction in the non-chemotherapy group was shown to be significantly lower (P = 0.031 by Gray's test) in a competing risk analysis. Death as a competing risk event needs to be appropriately considered in estimating a cumulative incidence of SEMS dysfunction, otherwise analytical results may be biased. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

  18. Semiparametric regression analysis of interval-censored competing risks data.

    PubMed

    Mao, Lu; Lin, Dan-Yu; Zeng, Donglin

    2017-09-01

    Interval-censored competing risks data arise when each study subject may experience an event or failure from one of several causes and the failure time is not observed directly but rather is known to lie in an interval between two examinations. We formulate the effects of possibly time-varying (external) covariates on the cumulative incidence or sub-distribution function of competing risks (i.e., the marginal probability of failure from a specific cause) through a broad class of semiparametric regression models that captures both proportional and non-proportional hazards structures for the sub-distribution. We allow each subject to have an arbitrary number of examinations and accommodate missing information on the cause of failure. We consider nonparametric maximum likelihood estimation and devise a fast and stable EM-type algorithm for its computation. We then establish the consistency, asymptotic normality, and semiparametric efficiency of the resulting estimators for the regression parameters by appealing to modern empirical process theory. In addition, we show through extensive simulation studies that the proposed methods perform well in realistic situations. Finally, we provide an application to a study on HIV-1 infection with different viral subtypes. © 2017, The International Biometric Society.

  19. 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…

  20. A parametric symmetry breaking transducer

    NASA Astrophysics Data System (ADS)

    Eichler, Alexander; Heugel, Toni L.; Leuch, Anina; Degen, Christian L.; Chitra, R.; Zilberberg, Oded

    2018-06-01

    Force detectors rely on resonators to transduce forces into a readable signal. Usually, these resonators operate in the linear regime and their signal appears amidst a competing background comprising thermal or quantum fluctuations as well as readout noise. Here, we demonstrate a parametric symmetry breaking transduction method that leads to a robust nonlinear force detection in the presence of noise. The force signal is encoded in the frequency at which the system jumps between two phase states which are inherently protected against phase noise. Consequently, the transduction effectively decouples from readout noise channels. For a controlled demonstration of the method, we experiment with a macroscopic doubly clamped string. Our method provides a promising paradigm for high-precision force detection.

  1. Quantifying the predictive accuracy of time-to-event models in the presence of competing risks.

    PubMed

    Schoop, Rotraut; Beyersmann, Jan; Schumacher, Martin; Binder, Harald

    2011-02-01

    Prognostic models for time-to-event data play a prominent role in therapy assignment, risk stratification and inter-hospital quality assurance. The assessment of their prognostic value is vital not only for responsible resource allocation, but also for their widespread acceptance. The additional presence of competing risks to the event of interest requires proper handling not only on the model building side, but also during assessment. Research into methods for the evaluation of the prognostic potential of models accounting for competing risks is still needed, as most proposed methods measure either their discrimination or calibration, but do not examine both simultaneously. We adapt the prediction error proposal of Graf et al. (Statistics in Medicine 1999, 18, 2529–2545) and Gerds and Schumacher (Biometrical Journal 2006, 48, 1029–1040) to handle models with competing risks, i.e. more than one possible event type, and introduce a consistent estimator. A simulation study investigating the behaviour of the estimator in small sample size situations and for different levels of censoring together with a real data application follows.

  2. 'Putting it into words': developing the RCGP competency descriptors to include 'at-risk behaviours'.

    PubMed

    Jones, Tim; Tracey, Sue

    2012-11-01

    As part of the Royal College of General Practitioners' (RCGP) arrangements to satisfy the GMC's requirement for Work Place Based Assessment (WPBAs) a range of 12 WPBA competencies was drawn up. Further to this the RCGP produced descriptors of the behaviours that would demonstrate a trainee had gained competence in that area. Recently the RCGP have expanded the rating scale available to educational supervisors at the time of a review to allow for a finding of 'Needs Further Development (NFD) - below expectations'. In the North of Scotland Deanery it has been recognised that a number of trainees are struggling to demonstrate competency in WPBA and to complete training. Reviewing how we could help these trainees and their educational supervisors there was recognition that early identification of these trainees would assist remedial action. Additionally, having reliable indicators of behaviours associated with a trainee in difficulty would aid the assessment of a trainee as 'NFD - below expectations'. Although many reliable descriptors of 'at-risk' behaviour exist, within frameworks and systems for doctors felt to be in difficulty these systems lie outwith the WPBA competency framework. This paper describes the work undertaken in the North of Scotland Deanery to modify the original table of descriptors for the 12 WPBA competencies to include an 'NFD - below expectations'/'at-risk' behaviours column. The descriptors of behaviours associated with trainees in difficulty have been aligned to the 12 WPBA competencies and used to populate the additional column in the descriptor table. The expectation is that the expanded table of descriptors will assist both in early identification of trainees' at-risk behaviours so that formative work can be engaged in at an early stage in an attachment, and also in the objective assessment of a trainee at an educational supervisor's review if they're in difficulties.

  3. Quantifying and estimating the predictive accuracy for censored time-to-event data with competing risks.

    PubMed

    Wu, Cai; Li, Liang

    2018-05-15

    This paper focuses on quantifying and estimating the predictive accuracy of prognostic models for time-to-event outcomes with competing events. We consider the time-dependent discrimination and calibration metrics, including the receiver operating characteristics curve and the Brier score, in the context of competing risks. To address censoring, we propose a unified nonparametric estimation framework for both discrimination and calibration measures, by weighting the censored subjects with the conditional probability of the event of interest given the observed data. The proposed method can be extended to time-dependent predictive accuracy metrics constructed from a general class of loss functions. We apply the methodology to a data set from the African American Study of Kidney Disease and Hypertension to evaluate the predictive accuracy of a prognostic risk score in predicting end-stage renal disease, accounting for the competing risk of pre-end-stage renal disease death, and evaluate its numerical performance in extensive simulation studies. Copyright © 2018 John Wiley & Sons, Ltd.

  4. A probabilistic strategy for parametric catastrophe insurance

    NASA Astrophysics Data System (ADS)

    Figueiredo, Rui; Martina, Mario; Stephenson, David; Youngman, Benjamin

    2017-04-01

    Economic losses due to natural hazards have shown an upward trend since 1980, which is expected to continue. Recent years have seen a growing worldwide commitment towards the reduction of disaster losses. This requires effective management of disaster risk at all levels, a part of which involves reducing financial vulnerability to disasters ex-ante, ensuring that necessary resources will be available following such events. One way to achieve this is through risk transfer instruments. These can be based on different types of triggers, which determine the conditions under which payouts are made after an event. This study focuses on parametric triggers, where payouts are determined by the occurrence of an event exceeding specified physical parameters at a given location, or at multiple locations, or over a region. This type of product offers a number of important advantages, and its adoption is increasing. The main drawback of parametric triggers is their susceptibility to basis risk, which arises when there is a mismatch between triggered payouts and the occurrence of loss events. This is unavoidable in said programmes, as their calibration is based on models containing a number of different sources of uncertainty. Thus, a deterministic definition of the loss event triggering parameters appears flawed. However, often for simplicity, this is the way in which most parametric models tend to be developed. This study therefore presents an innovative probabilistic strategy for parametric catastrophe insurance. It is advantageous as it recognizes uncertainties and minimizes basis risk while maintaining a simple and transparent procedure. A logistic regression model is constructed here to represent the occurrence of loss events based on certain loss index variables, obtained through the transformation of input environmental variables. Flood-related losses due to rainfall are studied. The resulting model is able, for any given day, to issue probabilities of occurrence of loss

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

    PubMed

    Li, Ruosha; Peng, Limin

    2014-10-01

    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.

  6. Computing Optimal Stochastic Portfolio Execution Strategies: A Parametric Approach Using Simulations

    NASA Astrophysics Data System (ADS)

    Moazeni, Somayeh; Coleman, Thomas F.; Li, Yuying

    2010-09-01

    Computing optimal stochastic portfolio execution strategies under appropriate risk consideration presents great computational challenge. We investigate a parametric approach for computing optimal stochastic strategies using Monte Carlo simulations. This approach allows reduction in computational complexity by computing coefficients for a parametric representation of a stochastic dynamic strategy based on static optimization. Using this technique, constraints can be similarly handled using appropriate penalty functions. We illustrate the proposed approach to minimize the expected execution cost and Conditional Value-at-Risk (CVaR).

  7. 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

  8. 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

  9. Competing risks regression for clustered data

    PubMed Central

    Zhou, Bingqing; Fine, Jason; Latouche, Aurelien; Labopin, Myriam

    2012-01-01

    A population average regression model is proposed to assess the marginal effects of covariates on the cumulative incidence function when there is dependence across individuals within a cluster in the competing risks setting. This method extends the Fine–Gray proportional hazards model for the subdistribution to situations, where individuals within a cluster may be correlated due to unobserved shared factors. Estimators of the regression parameters in the marginal model are developed under an independence working assumption where the correlation across individuals within a cluster is completely unspecified. The estimators are consistent and asymptotically normal, and variance estimation may be achieved without specifying the form of the dependence across individuals. A simulation study evidences that the inferential procedures perform well with realistic sample sizes. The practical utility of the methods is illustrated with data from the European Bone Marrow Transplant Registry. PMID:22045910

  10. Risk Factors of Mortality from All Asbestos-Related Diseases: A Competing Risk Analysis.

    PubMed

    Abós-Herràndiz, Rafael; Rodriguez-Blanco, Teresa; Garcia-Allas, Isabel; Rosell-Murphy, Isabel-Magdalena; Albertí-Casas, Constança; Tarrés, Josep; Krier-Günther, Illona; Martinez-Artés, Xavier; Orriols, Ramon; Grimau-Malet, Isidre; Canela-Soler, Jaume

    2017-01-01

    The mortality from all malignant and nonmalignant asbestos-related diseases remains unknown. The authors assessed the incidence and risk factors for all asbestos-related deaths. The sample included 544 patients from an asbestos-exposed community in the area of Barcelona (Spain), between Jan 1, 1970, and Dec 31, 2006. Competing risk regression through a subdistribution hazard analysis was used to estimate risk factors for the outcomes. Asbestos-related deaths were observed in 167 (30.7%) patients and 57.5% of these deaths were caused by some type of mesothelioma. The incidence rate after diagnosis was 3,600 per 100,000 person-years. In 7.5% of patients death was non-asbestos-related, while pleural and peritoneal mesothelioma were identified in 87 (16.0%) and 18 (3.3%) patients, respectively. Age, sex, household exposure, cumulative nonmalignant asbestos-related disease, and single malignant pathology were identified as risk factors for asbestos-related death. These findings suggest the need to develop a preventive approach to the community and to improve the clinical follow-up process of these patients.

  11. Ultra-wideband and high-gain parametric amplification in telecom wavelengths with an optimally mode-matched PPLN waveguide.

    PubMed

    Sua, Yong Meng; Chen, Jia-Yang; Huang, Yu-Ping

    2018-06-15

    We report a wideband optical parametric amplification (OPA) over 14 THz covering telecom S, C, and L bands with observed maximum parametric gain of 38.3 dB. The OPA is realized through cascaded second-harmonic generation and difference-frequency generation (cSHG-DFG) in a 2 cm periodically poled LiNbO 3 (PPLN) waveguide. With tailored cross section geometry, the waveguide is optimally mode matched for efficient cascaded nonlinear wave mixing. We also identify and study the effect of competing nonlinear processes in this cSHG-DFG configuration.

  12. The prognostic role of body mass index on mortality amongst the middle-aged and elderly: a competing risk analysis.

    PubMed

    Ghaem Maralani, Haleh; Tai, Bee Choo; Wong, Tien Y; Tai, E Shyong; Li, Jialiang; Wang, Jie Jin; Mitchell, Paul

    2014-01-01

    To determine the relationship between body mass index (BMI) including its 5-year changes and mortality, and compare the results obtained using Cox and competing risks models. Our study subjects included 2216 persons aged ≥49 years who participated in the Blue Mountains Eye Study, Australia between 1992 and 1994, and returned for further follow-up examinations between 1997 and 1999. We examined the relationship between BMI and mortality using cubic spline. The Cox and competing risks models were used to assess the associations between baseline BMI and its 5-year changes with all-cause and cause-specific mortality. Amongst subjects aged ≤70 years, the relationship between BMI and all-cause mortality was U-shaped. For those aged >70 years, an L-shaped relationship was seen with no elevation in risk amongst the overweight/obese. Based on the competing risks model, obesity at baseline was associated with increased risk of cardiovascular death and reduction in BMI at 5-year was linked to an increase risk of cancer death amongst those aged ≤70 years. The cause-specific Cox model showed that reduction in BMI at 5-year was associated with cancer-death regardless of age, and with cardiovascular deaths among subjects aged ≤70 years. Cox regression model showed larger magnitude of effect with wider confidence interval as compared with competing risks model. Conditions associated with obesity are more likely to affect mortality among subjects aged ≤70 years, but not among those aged over 70 years. Cox model shows larger magnitude of effect in comparison with competing risks model. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. 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.

  14. Surrogate endpoints and competing risk of death in cardiac arrest research.

    PubMed

    McCredie, Victoria A; Scales, Damon C

    2016-06-29

    We urgently need new therapies to improve outcomes after cardiac arrest. Initial studies typically target surrogate endpoints, and these studies help to inform subsequent larger trials that are powered to measure more patient-orientated clinical outcomes such as survival. The competing risk of death and premature assessment of neurological prognosis pose significant challenges to measuring these surrogate endpoints after cardiac arrest.

  15. Attitudes of older adults with serious competing health risks toward their implantable cardioverter-defibrillators: a pilot study.

    PubMed

    Green, Ariel R; Boyd, Cynthia M; Rickard, John; Gomon, Robert; Leff, Bruce

    2015-12-23

    In elderly heart failure patients, the survival benefit of implantable cardioverter-defibrillators (ICDs) may be attenuated due to competing health risks, and the risk of adverse outcomes magnified. Our objective was to examine older adults' attitudes towards ICD implantation in the context of competing health risks, exploring the determinants of ICD decision-making among a group of patients who had faced the decision in the past. Telephone survey with a qualitative component. Patients were age ≥70 with single- or dual-chamber ICDs from a single academic cardiac device clinic. Health status was assessed with the Vulnerable Elders Survey (VES-13). Responses to open-ended questions were transcribed verbatim; an "editing analysis" approach was used to extract themes. Forty-four ICD recipients participated (mean age 77.5 years). Nineteen participants (43%) had VES-13 scores ≥3, indicating a 50% likelihood of death or functional decline within 2 years. Twenty-one participants (48%) had received prior ICD shocks. Forty participants (91%) said they would "definitely" choose to get an ICD again in their current health. By and large, patients revealed a strong desire to extend life, expressed complete confidence in the lifesaving capabilities of their ICDs, and did not describe consideration of competing health risks. In this pilot telephone survey with a qualitative component, nearly all older adults with ICDs would still choose to get an ICD despite high short-term risk of death or health deterioration. These findings suggest the need to partner more effectively with patients and families to decide how best to use medical technologies, particularly for older adults with competing risks.

  16. Risks of Death and Stroke in Patients Undergoing Hemodialysis With New-Onset Atrial Fibrillation: A Competing-Risk Analysis of a Nationwide Cohort.

    PubMed

    Shih, Chia-Jen; Ou, Shuo-Ming; Chao, Pei-Wen; Kuo, Shu-Chen; Lee, Yi-Jung; Yang, Chih-Yu; Tarng, Der-Cherng; Lin, Chih-Ching; Huang, Po-Hsun; Li, Szu-Yuan; Chen, Yung-Tai

    2016-01-19

    Whether oral anticoagulant use should be considered in patients undergoing hemodialysis with atrial fibrillation (AF) remains controversial because of the uncertainty regarding risk-benefit assessments. The purpose of this study was to investigate the risk of ischemic stroke in patients undergoing hemodialysis with new-onset AF, in comparison with those without arrhythmia. This nationwide, population-based, propensity score-matched cohort study used data from Taiwan's National Health Insurance Research Database during 1998 to 2011 for patients on hemodialysis with new-onset nonvalvular AF and matched subjects without arrhythmia. The clinical end points were ischemic stroke (fatal or nonfatal), all-cause death, and other serious adverse cardiovascular events. In comparison with the matched cohort, patients with AF (n=6772) had higher risks of ischemic stroke (adjusted hazard ratio [aHR], 1.27; 95% confidence interval [CI], 1.13-1.43), all-cause death (aHR, 1.59; 95% CI, 1.52-1.67), in-hospital cardiovascular death (aHR, 1.83; 95% CI, 1.71-1.94), myocardial infarction (aHR, 1.33; 95% CI, 1.17-1.51), and hospitalization for heart failure (aHR, 1.90; 95% CI, 1.76-2.05). After considering in-hospital death as a competing risk, AF significantly increased the risk of heart failure (HR, 1.56; 95% CI, 1.45-1.68), but not those of ischemic stroke and myocardial infarction. Additionally, the predictive value of the CHA2DS2-VASc score for ischemic stroke was diminished in the competing-risk model. The risk of stroke was only modestly higher in patients undergoing hemodialysis with new-onset AF than in those without AF, and it became insignificant when accounting for the competing risk of in-hospital death. © 2015 American Heart Association, Inc.

  17. [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.

  18. A Strategy for a Parametric Flood Insurance Using Proxies

    NASA Astrophysics Data System (ADS)

    Haraguchi, M.; Lall, U.

    2017-12-01

    Traditionally, the design of flood control infrastructure and flood plain zoning require the estimation of return periods, which have been calculated by river hydraulic models with rainfall-runoff models. However, this multi-step modeling process leads to significant uncertainty to assess inundation. In addition, land use change and changing climate alter the potential losses, as well as make the modeling results obsolete. For these reasons, there is a strong need to create parametric indexes for the financial risk transfer for large flood events, to enable rapid response and recovery. Hence, this study examines the possibility of developing a parametric flood index at the national or regional level in Asia, which can be quickly mobilized after catastrophic floods. Specifically, we compare a single trigger based on rainfall index with multiple triggers using rainfall and streamflow indices by conducting case studies in Bangladesh and Thailand. The proposed methodology is 1) selecting suitable indices of rainfall and streamflow (if available), 2) identifying trigger levels for specified return periods for losses using stepwise and logistic regressions, 3) measuring the performance of indices, and 4) deriving return periods of selected windows and trigger levels. Based on the methodology, actual trigger levels were identified for Bangladesh and Thailand. Models based on multiple triggers reduced basis risks, an inherent problem in an index insurance. The proposed parametric flood index can be applied to countries with similar geographic and meteorological characteristics, and serve as a promising method for ex-ante risk financing for developing countries. This work is intended to be a preliminary work supporting future work on pricing risk transfer mechanisms in ex-ante risk finance.

  19. Global, Multi-Objective Trajectory Optimization With Parametric Spreading

    NASA Technical Reports Server (NTRS)

    Vavrina, Matthew A.; Englander, Jacob A.; Phillips, Sean M.; Hughes, Kyle M.

    2017-01-01

    Mission design problems are often characterized by multiple, competing trajectory optimization objectives. Recent multi-objective trajectory optimization formulations enable generation of globally-optimal, Pareto solutions via a multi-objective genetic algorithm. A byproduct of these formulations is that clustering in design space can occur in evolving the population towards the Pareto front. This clustering can be a drawback, however, if parametric evaluations of design variables are desired. This effort addresses clustering by incorporating operators that encourage a uniform spread over specified design variables while maintaining Pareto front representation. The algorithm is demonstrated on a Neptune orbiter mission, and enhanced multidimensional visualization strategies are presented.

  20. 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…

  1. 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

  2. Risk factors for unplanned readmissions in older adult trauma patients in Washington State: a competing risk analysis.

    PubMed

    Fawcett, Vanessa J; Flynn-O'Brien, Katherine T; Shorter, Zeynep; Davidson, Giana H; Bulger, Eileen; Rivara, Frederick P; Arbabi, Saman

    2015-03-01

    Hospital readmission is a significant contributor to increasing health care use related to caring for older trauma patients. This study was undertaken with the following aims: determine the proportion of older adult trauma patients who experience unplanned readmission, as well as risk factors for these readmissions and identify the most common readmission diagnoses among these patients. We conducted a retrospective cohort study of trauma patients age 55 years and older who survived their hospitalization at a statewide trauma center between 2009 and 2010. Linking 3 statewide databases, nonelective readmission rates were calculated for 30 days, 6 months, and 1 year after index discharge. Competing risk regression was used to determine risk factors for readmission and account for the competing risk of dying without first being readmitted. Subhazard ratios (SHR) are reported, indicating the relative risk of readmission by 30 days, 6 months, and 1 year. The cumulative readmission rates for the 14,536 participants were 7.9%, 18.9%, and 25.2% at 30 days, 6 months, and 1 year, respectively. In multivariable models, the strongest risk factors for readmission at 1 year (based on magnitude of SHR) were severe head injury (adjusted SHR = 1.47; 95% CI, 1.24-1.73) and disposition to a skilled nursing facility (SHR = 1.54; 95% CI, 1.39-1.71). The diagnoses most commonly associated with readmission were atrial fibrillation, anemia, and congestive heart failure. In this statewide study, unplanned readmissions after older adult trauma occurred frequently up to 1 year after discharge, particularly for patients who sustained severe head trauma and who could not be discharged home independently. Examining common readmission diagnoses might inform the development of interventions to prevent unplanned readmissions. Copyright © 2015 American College of Surgeons. All rights reserved.

  3. Influence of Competing Risks on Estimating the Expected Benefit of Warfarin Among Atrial Fibrillation Patients not Currently Taking Anticoagulants: the ATRIA Study

    PubMed Central

    Ashburner, Jeffrey M.; Go, Alan S.; Chang, Yuchiao; Fang, Margaret C.; Fredman, Lisa; Applebaum, Katie M.; Singer, Daniel E.

    2016-01-01

    Background/Objectives To date, studies examining the association between warfarin therapy and incidence of ischemic stroke among patients with atrial fibrillation (AF) have not accounted for the competing risk of death. Competing risk analysis may provide greater understanding of the “real world” impact of anticoagulation on stroke risk over a multiyear time span. Design Cohort study Setting ATRIA Study community-based cohort Participants 13,559 adults with nonvalvular AF between 1996 and 2003. Measurements All events were clinician-adjudicated. We used extended Cox regression with longitudinal warfarin exposure to estimate cause-specific hazard ratios (HR) for thromboembolism (TE) and the competing risk event (all cause death). The Fine and Gray subdistribution regression approach was used to estimate this association while accounting for competing death events. As a secondary analysis, follow-up was limited to 1, 3, and 5-years. Results The rate of death was much higher in the non-warfarin group (8.1 deaths/100 person-years) compared to the warfarin group (5.5 deaths/100 person-years). The cause-specific HR indicated a large reduction in TE with warfarin use (adjusted HR: 0.57, 95% CI: 0.50–0.65). However, after accounting for competing death events, this association was substantially attenuated (adjusted HR: 0.87, 95% CI: 0.77–0.99). In analyses limited to 1-year of follow-up with fewer competing death events, the results for models that did and did not account for competing risks were similar. Conclusion Analyses accounting for competing death events may provide a more realistic estimate of the longer-term stroke prevention benefits of anticoagulants for patients with AF, particularly those who are not currently treated with anticoagulants. PMID:27861698

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

    PubMed

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

    2016-01-01

    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. 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). 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. 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 did preschoolers without significant IQD, though the

  5. Parametric vs. non-parametric statistics of low resolution electromagnetic tomography (LORETA).

    PubMed

    Thatcher, R W; North, D; Biver, C

    2005-01-01

    This study compared the relative statistical sensitivity of non-parametric and parametric statistics of 3-dimensional current sources as estimated by the EEG inverse solution Low Resolution Electromagnetic Tomography (LORETA). One would expect approximately 5% false positives (classification of a normal as abnormal) at the P < .025 level of probability (two tailed test) and approximately 1% false positives at the P < .005 level. EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) from 43 normal adult subjects were imported into the Key Institute's LORETA program. We then used the Key Institute's cross-spectrum and the Key Institute's LORETA output files (*.lor) as the 2,394 gray matter pixel representation of 3-dimensional currents at different frequencies. The mean and standard deviation *.lor files were computed for each of the 2,394 gray matter pixels for each of the 43 subjects. Tests of Gaussianity and different transforms were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of parametric vs. non-parametric statistics were compared using a "leave-one-out" cross validation method in which individual normal subjects were withdrawn and then statistically classified as being either normal or abnormal based on the remaining subjects. Log10 transforms approximated Gaussian distribution in the range of 95% to 99% accuracy. Parametric Z score tests at P < .05 cross-validation demonstrated an average misclassification rate of approximately 4.25%, and range over the 2,394 gray matter pixels was 27.66% to 0.11%. At P < .01 parametric Z score cross-validation false positives were 0.26% and ranged from 6.65% to 0% false positives. The non-parametric Key Institute's t-max statistic at P < .05 had an average misclassification error rate of 7.64% and ranged from 43.37% to 0.04% false positives. The nonparametric t-max at P < .01 had an average misclassification rate

  6. Contextual Risk and Parenting as Predictors of Effortful Control and Social Competence in Preschool Children

    ERIC Educational Resources Information Center

    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…

  7. Self-Reported Risk and Delinquent Behavior and Problem Behavioral Intention in Hong Kong Adolescents: The Role of Moral Competence and Spirituality.

    PubMed

    Shek, Daniel T L; Zhu, Xiaoqin

    2018-01-01

    Based on the six-wave data collected from Grade 7 to Grade 12 students ( N = 3,328 at Wave 1), this pioneer study examined the development of problem behaviors (risk and delinquent behavior and problem behavioral intention) and the predictors (moral competence and spirituality) among adolescents in Hong Kong. Individual growth curve models revealed that while risk and delinquent behavior accelerated and then slowed down in the high school years, adolescent problem behavioral intention slightly accelerated over time. After controlling the background socio-demographic factors, moral competence and spirituality were negatively associated with risk and delinquent behavior as well as problem behavioral intention across all waves as predicted. Regarding the rate of change in the outcome measures, while the initial level of spirituality was positively linked to the growth rate of risk and delinquent behavior, the initial level of moral competence was negatively associated with the growth rate of problem behavioral intention. The theoretical and practical implications of the present findings are discussed with reference to the role of moral competence and spirituality in the development of adolescent problem behavior.

  8. Self-Reported Risk and Delinquent Behavior and Problem Behavioral Intention in Hong Kong Adolescents: The Role of Moral Competence and Spirituality

    PubMed Central

    Shek, Daniel T. L.; Zhu, Xiaoqin

    2018-01-01

    Based on the six-wave data collected from Grade 7 to Grade 12 students (N = 3,328 at Wave 1), this pioneer study examined the development of problem behaviors (risk and delinquent behavior and problem behavioral intention) and the predictors (moral competence and spirituality) among adolescents in Hong Kong. Individual growth curve models revealed that while risk and delinquent behavior accelerated and then slowed down in the high school years, adolescent problem behavioral intention slightly accelerated over time. After controlling the background socio-demographic factors, moral competence and spirituality were negatively associated with risk and delinquent behavior as well as problem behavioral intention across all waves as predicted. Regarding the rate of change in the outcome measures, while the initial level of spirituality was positively linked to the growth rate of risk and delinquent behavior, the initial level of moral competence was negatively associated with the growth rate of problem behavioral intention. The theoretical and practical implications of the present findings are discussed with reference to the role of moral competence and spirituality in the development of adolescent problem behavior. PMID:29651269

  9. Comparing multiple competing interventions in the absence of randomized trials using clinical risk-benefit analysis

    PubMed Central

    2012-01-01

    Background To demonstrate the use of risk-benefit analysis for comparing multiple competing interventions in the absence of randomized trials, we applied this approach to the evaluation of five anticoagulants to prevent thrombosis in patients undergoing orthopedic surgery. Methods Using a cost-effectiveness approach from a clinical perspective (i.e. risk benefit analysis) we compared thromboprophylaxis with warfarin, low molecular weight heparin, unfractionated heparin, fondaparinux or ximelagatran in patients undergoing major orthopedic surgery, with sub-analyses according to surgery type. Proportions and variances of events defining risk (major bleeding) and benefit (thrombosis averted) were obtained through a meta-analysis and used to define beta distributions. Monte Carlo simulations were conducted and used to calculate incremental risks, benefits, and risk-benefit ratios. Finally, net clinical benefit was calculated for all replications across a range of risk-benefit acceptability thresholds, with a reference range obtained by estimating the case fatality rate - ratio of thrombosis to bleeding. Results The analysis showed that compared to placebo ximelagatran was superior to other options but final results were influenced by type of surgery, since ximelagatran was superior in total knee replacement but not in total hip replacement. Conclusions Using simulation and economic techniques we demonstrate a method that allows comparing multiple competing interventions in the absence of randomized trials with multiple arms by determining the option with the best risk-benefit profile. It can be helpful in clinical decision making since it incorporates risk, benefit, and personal risk acceptance. PMID:22233221

  10. Type 2 diabetes, adiposity and cancer morbidity and mortality risk taking into account competing risk of noncancer deaths in a prospective cohort setting

    PubMed Central

    Gullberg, Bo; Sonestedt, Emily; Stocks, Tanja; Bjartell, Anders; Wirfält, Elisabet; Wallström, Peter; Orho‐Melander, Marju

    2017-01-01

    Type 2 diabetes (T2D) and adiposity associate with increased risk of several cancers, but the impact of competing risk of noncancer deaths on these associations is not known. We prospectively examined participants in the Malmö Diet and Cancer Study aged 44–73 years with no history of cancer at baseline (n = 26,953, 43% men). T2D was ascertained at baseline and during follow‐up, and body mass index (BMI) and waist circumference (WC) at baseline. Multivariable cause‐specific hazard ratios (HR) and subdistribution hazard ratios (sHR), taking into account noncancer deaths, were estimated using Cox‐ and competing risk regression. During follow‐up (mean 17 years), 7,061 incident cancers (3,220 obesity‐related cancer types) and 2,848 cancer deaths occurred. BMI and WC were associated with increased risk of obesity‐related cancer incidence and cancer mortality. In T2D subjects, risk of obesity‐related cancer was elevated among men (HR = 1.31, 95% CI: 1.12–1.54; sHR = 1.29, 95% CI: 1.10–1.52), and cancer mortality among both men and women (HR = 1.34, 95% CI: 1.20–1.49; sHR = 1.30, 95% CI: 1.16–1.45). There was no elevated actual risk of cancer death in T2D patients with long disease duration (sHR = 1.00, 95% CI: 0.83–1.20). There was a significant additive effect of T2D and adiposity on risk of obesity‐related cancer and cancer mortality. In conclusion, detection bias may partially explain the increased risk of cancer morbidity among T2D patients. Both excess risk of competing events among patients with T2D and depletion of susceptibles due to earlier cancer detection will lower the actual risk of cancer, particularly with longer diabetes duration and at older ages. PMID:28593629

  11. Front-line intraperitoneal versus intravenous chemotherapy in stage III-IV epithelial ovarian, tubal, and peritoneal cancer with minimal residual disease: a competing risk analysis.

    PubMed

    Chang, Yen-Hou; Li, Wai-Hou; Chang, Yi; Peng, Chia-Wen; Cheng, Ching-Hsuan; Chang, Wei-Pin; Chuang, Chi-Mu

    2016-03-17

    In the analysis of survival data for cancer patients, the problem of competing risks is often ignored. Competing risks have been recognized as a special case of time-to-event analysis. The conventional techniques for time-to-event analysis applied in the presence of competing risks often give biased or uninterpretable results. Using a prospectively collected administrative health care database in a single institution, we identified patients diagnosed with stage III or IV primary epithelial ovarian, tubal, and peritoneal cancers with minimal residual disease after primary cytoreductive surgery between 1995 and 2012. Here, we sought to evaluate whether intraperitoneal chemotherapy outperforms intravenous chemotherapy in the presence of competing risks. Unadjusted and multivariable subdistribution hazards models were applied to this database with two types of competing risks (cancer-specific mortality and other-cause mortality) coded to measure the relative effects of intraperitoneal chemotherapy. A total of 1263 patients were recruited as the initial cohort. After propensity score matching, 381 patients in each arm entered into final competing risk analysis. Cumulative incidence estimates for cancer-specific mortality were statistically significantly lower (p = 0.017, Gray test) in patients receiving intraperitoneal chemotherapy (5-year estimates, 34.5%; 95% confidence interval [CI], 29.5-39.6%, and 10-year estimates, 60.7%; 95% CI, 52.2-68.0%) versus intravenous chemotherapy (5-year estimates, 41.3%; 95% CI, 36.2-46.3%, and 10-year estimates, 67.5%, 95% CI, 61.6-72.7%). In subdistribution hazards analysis, for cancer-specific mortality, intraperitoneal chemotherapy outperforms intravenous chemotherapy (Subdistribution hazard ratio, 0.82; 95% CI, 0.70-0.96) after correcting other covariates. In conclusion, results from this comparative effectiveness study provide supportive evidence for previous published randomized trials that intraperitoneal chemotherapy

  12. Clinical competence of Guatemalan and Mexican physicians for family dysfunction management.

    PubMed

    Cabrera-Pivaral, Carlos Enrique; Orozco-Valerio, María de Jesús; Celis-de la Rosa, Alfredo; Covarrubias-Bermúdez, María de Los Ángeles; Zavala-González, Marco Antonio

    2017-01-01

    To evaluate the clinical competence of Mexican and Guatemalan physicians to management the family dysfunction. Cross comparative study in four care units first in Guadalajara, Mexico, and four in Guatemala, Guatemala, based on a purposeful sampling, involving 117 and 100 physicians, respectively. Clinical competence evaluated by validated instrument integrated for 187 items. Non-parametric descriptive and inferential statistical analysis was performed. The percentage of Mexican physicians with high clinical competence was 13.7%, medium 53%, low 24.8% and defined by random 8.5%. For the Guatemalan physicians'14% was high, average 63%, and 23% defined by random. There were no statistically significant differences between healthcare country units, but between the medium of Mexicans (0.55) and Guatemalans (0.55) (p = 0.02). The proportion of the high clinical competency of Mexican physicians' was as Guatemalans.

  13. Therapeutic risk management of clinical-legal dilemmas: should it be a core competency?

    PubMed

    Simon, Robert I; Shuman, Daniel W

    2009-01-01

    Therapeutic risk management of clinical-legal dilemmas achieves an optimal alignment between clinical competence and an understanding of legal concerns applicable to psychiatric practice. Understanding how psychiatry and law interact in frequently occurring clinical situations is essential for effective patient care. Successful management of clinical-legal dilemmas also avoids unnecessary, counterproductive defensive practices.

  14. The Role of Child Temperament on Head Start Preschoolers' Social Competence in the Context of Cumulative Risk

    ERIC Educational Resources Information Center

    Corapci, Feyza

    2008-01-01

    This study examined the main and interactive effects of cumulative risk and child temperament on teacher ratings of social competence and observer ratings of peer play in a sample of Head Start preschoolers. A cumulative risk index (CRI) was computed by summing the total number of risk factors for each family. There was a difference in the…

  15. Incidence of cardiovascular events and associated risk factors in kidney transplant patients: a competing risks survival analysis.

    PubMed

    Seoane-Pillado, María Teresa; Pita-Fernández, Salvador; Valdés-Cañedo, Francisco; Seijo-Bestilleiro, Rocio; Pértega-Díaz, Sonia; Fernández-Rivera, Constantino; Alonso-Hernández, Ángel; González-Martín, Cristina; Balboa-Barreiro, Vanesa

    2017-03-07

    The high prevalence of cardiovascular risk factors among the renal transplant population accounts for increased mortality. The aim of this study is to determine the incidence of cardiovascular events and factors associated with cardiovascular events in these patients. An observational ambispective follow-up study of renal transplant recipients (n = 2029) in the health district of A Coruña (Spain) during the period 1981-2011 was completed. Competing risk survival analysis methods were applied to estimate the cumulative incidence of developing cardiovascular events over time and to identify which characteristics were associated with the risk of these events. Post-transplant cardiovascular events are defined as the presence of myocardial infarction, invasive coronary artery therapy, cerebral vascular events, new-onset angina, congestive heart failure, rhythm disturbances, peripheral vascular disease and cardiovascular disease and death. The cause of death was identified through the medical history and death certificate using ICD9 (390-459, except: 427.5, 435, 446, 459.0). The mean age of patients at the time of transplantation was 47.0 ± 14.2 years; 62% were male. 16.5% had suffered some cardiovascular disease prior to transplantation and 9.7% had suffered a cardiovascular event. The mean follow-up period for the patients with cardiovascular event was 3.5 ± 4.3 years. Applying competing risk methodology, it was observed that the accumulated incidence of the event was 5.0% one year after transplantation, 8.1% after five years, and 11.9% after ten years. After applying multivariate models, the variables with an independent effect for predicting cardiovascular events are: male sex, age of recipient, previous cardiovascular disorders, pre-transplant smoking and post-transplant diabetes. This study makes it possible to determine in kidney transplant patients, taking into account competitive events, the incidence of post-transplant cardiovascular events and

  16. 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

  17. Multiple Frequency Parametric Sonar

    DTIC Science & Technology

    2015-09-28

    300003 1 MULTIPLE FREQUENCY PARAMETRIC SONAR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...a method for increasing the bandwidth of a parametric sonar system by using multiple primary frequencies rather than only two primary frequencies...2) Description of Prior Art [0004] Parametric sonar generates narrow beams at low frequencies by projecting sound at two distinct primary

  18. What should the African health workforce know about disasters? Proposed competencies for strengthening public health disaster risk management education in Africa.

    PubMed

    Olu, Olushayo; Usman, Abdulmumini; Kalambay, Kalula; Anyangwe, Stella; Voyi, Kuku; Orach, Christopher Garimoi; Azazh, Aklilu; Mapatano, Mala Ali; Nsenga, Ngoy; Manga, Lucien; Woldetsadik, Solomon; Nguessan, Francois; Benson, Angela

    2018-04-02

    As part of efforts to implement the human resources capacity building component of the African Regional Strategy on Disaster Risk Management (DRM) for the health sector, the African Regional Office of the World Health Organization, in collaboration with selected African public health training institutions, followed a multistage process to develop core competencies and curricula for training the African health workforce in public health DRM. In this article, we describe the methods used to develop the competencies, present the identified competencies and training curricula, and propose recommendations for their integration into the public health education curricula of African member states. We conducted a pilot research using mixed methods approaches to develop and test the applicability and feasibility of a public health disaster risk management curriculum for training the African health workforce. We identified 14 core competencies and 45 sub-competencies/training units grouped into six thematic areas: 1) introduction to DRM; 2) operational effectiveness; 3) effective leadership; 4) preparedness and risk reduction; 5) emergency response and 6) post-disaster health system recovery. These were defined as the skills and knowledge that African health care workers should possess to effectively participate in health DRM activities. To suit the needs of various categories of African health care workers, three levels of training courses are proposed: basic, intermediate, and advanced. The pilot test of the basic course among a cohort of public health practitioners in South Africa demonstrated their relevance. These competencies compare favourably to the findings of other studies that have assessed public health DRM competencies. They could provide a framework for scaling up the capacity development of African healthcare workers in the area of public health DRM; however further validation of the competencies is required through additional pilot courses and follow up of

  19. Evaluation of Death among the Patients Undergoing Permanent Pacemaker Implantation: A Competing Risks Analysis.

    PubMed

    Ghaem, Haleh; Ghorbani, Mohammad; Zare Dorniani, Samira

    2017-06-01

    Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. The present study aimed to determine the association between some predictive variables and all-cause and cause-specific mortality in the patients who had undergone pacemaker implantation. This study was conducted on 1207 patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar 2002 to Mar 2012. The variables that existed in the patients' medical records included sex, diabetes mellitus, obesity, cerebrovascular accident, cardiomegaly, smoking, hypertension, ischemic heart disease, congenital heart disease, sick sinus syndrome, and atrial fibrillation. Competing risks model was used to assess the association between the predictive variables and cause-specific (i.e., cardiac and vascular) mortality. The patients' mean age was 66.32±17.92 yr (70.62±14.45 yr in the patients with single-chamber pacemakers vs. 61.91±17.69 yr in those with two-chamber pacemakers) ( P <0.001). Sick sinus syndrome and age increased the risk of all-cause mortality, while two-chamber pacemaker decreased this risk. Obesity increased the risk of cardiac death, and diabetes mellitus and heart valve disease increased the risk of vascular death. The variables predicting mortality in all-cause model were completely different from those in cause-specific model. Moreover, death in such patients may occur due to reasons other than pacemaker. Therefore, future studies, particularly prospective ones, are recommended to use competing risks models.

  20. Evaluation of Death among the Patients Undergoing Permanent Pacemaker Implantation: A Competing Risks Analysis

    PubMed Central

    GHAEM, Haleh; GHORBANI, Mohammad; ZARE DORNIANI, Samira

    2017-01-01

    Background: Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. The present study aimed to determine the association between some predictive variables and all-cause and cause-specific mortality in the patients who had undergone pacemaker implantation. Methods: This study was conducted on 1207 patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar 2002 to Mar 2012. The variables that existed in the patients’ medical records included sex, diabetes mellitus, obesity, cerebrovascular accident, cardiomegaly, smoking, hypertension, ischemic heart disease, congenital heart disease, sick sinus syndrome, and atrial fibrillation. Competing risks model was used to assess the association between the predictive variables and cause-specific (i.e., cardiac and vascular) mortality. Results: The patients’ mean age was 66.32±17.92 yr (70.62±14.45 yr in the patients with single-chamber pacemakers vs. 61.91±17.69 yr in those with two-chamber pacemakers) (P<0.001). Sick sinus syndrome and age increased the risk of all-cause mortality, while two-chamber pacemaker decreased this risk. Obesity increased the risk of cardiac death, and diabetes mellitus and heart valve disease increased the risk of vascular death. Conclusion: The variables predicting mortality in all-cause model were completely different from those in cause-specific model. Moreover, death in such patients may occur due to reasons other than pacemaker. Therefore, future studies, particularly prospective ones, are recommended to use competing risks models. PMID:28828325

  1. 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…

  2. Parametric manipulation of the conflict signal and control-state adaptation.

    PubMed

    Forster, Sarah E; Carter, Cameron S; Cohen, Jonathan D; Cho, Raymond Y

    2011-04-01

    Mechanisms by which the brain monitors and modulates performance are an important focus of recent research. The conflict-monitoring hypothesis posits that the ACC detects conflict between competing response pathways which, in turn, signals for enhanced control. The N2, an ERP component that has been localized to ACC, has been observed after high conflict stimuli. As a candidate index of the conflict signal, the N2 would be expected to be sensitive to the degree of response conflict present, a factor that depends on both the features of external stimuli and the internal control state. In the present study, we sought to explore the relationship between N2 amplitude and these variables through use of a modified Eriksen flankers task in which target-distracter compatibility was parametrically varied. We hypothesized that greater target-distracter incompatibility would result in higher levels of response conflict, as indexed by both behavior and the N2 component. Consistent with this prediction, there were parametric degradations in behavioral performance and increases in N2 amplitudes with increasing incompatibility. Further, increasingly incompatible stimuli led to the predicted parametric increases in control on subsequent incompatible trials as evidenced by enhanced performance and reduced N2 amplitudes. These findings suggest that the N2 component and associated behavioral performance are finely sensitive to the degree of response conflict present and to the control adjustments that result from modulations in conflict.

  3. Learning at work: competence development or competence-stress.

    PubMed

    Paulsson, Katarina; Ivergård, Toni; Hunt, Brian

    2005-03-01

    Changes in work and the ways in which it is carried out bring a need for upgrading workplace knowledge, skills and competencies. In today's workplaces, and for a number of reasons, workloads are higher than ever and stress is a growing concern (Health Risk Soc. 2(2) (2000) 173; Educat. Psychol. Meas. 61(5) (2001) 866). Increased demand for learning brings a risk that this will be an additional stress factor and thus a risk to health. Our research study is based on the control-demand-support model of Karasek and Theorell (Health Work: Stress, Productivity and the Reconstruction of Working Life, Basic Books/Harper, New York, 1990). We have used this model for our own empirical research with the aim to evaluate the model in the modern workplace. Our research enables us to expand the model in the light of current workplace conditions-especially those relating to learning. We report empirical data from a questionnaire survey of working conditions in two different branches of industry. We are able to define differences between companies in terms of working conditions and competence development. We describe and discuss the effects these conditions have on workplace competence development. Our research results show that increased workers' control of the learning process makes competence development more stimulating, is likely to simplify the work and reduces (learning-related) stress. It is therefore important that learning at work allows employees to control their learning and also allows time for the process of learning and reflection.

  4. 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.

  5. Autonomy, Competence and Non-interference.

    PubMed

    Roberts, Joseph T F

    2017-12-30

    In light of the variety of uses of the term autonomy in recent bioethics literature, in this paper, I suggest that competence, not being as contested, is better placed to play the anti-paternalistic role currently assigned to autonomy. The demonstration of competence, I will argue, can provide individuals with robust spheres of non-interference in which they can pursue their lives in accordance with their own values. This protection from paternalism is achieved by granting individuals rights to non-interference upon demonstration of competence. In this paper, I present a risk-sensitive account of competence as a means of grounding rights to non-interference. On a risk-sensitive account of competence individuals demonstrate their competence by exercising three capacities to the extent necessary to meet a threshold determined by the riskiness of the decision. These three capacities are the capacity to (i) acquire knowledge, (ii) use instrumental rationality, and (iii) form and revise a life plan.

  6. 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,…

  7. 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…

  8. 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

  9. Rephasing invariant parametrization of flavor mixing

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Hun

    A new rephasing invariant parametrization for the 3 x 3 CKM matrix, called (x, y) parametrization, is introduced and the properties and applications of the parametrization are discussed. The overall phase condition leads this parametrization to have only six rephsing invariant parameters and two constraints. Its simplicity and regularity become apparent when it is applied to the one-loop RGE (renormalization group equations) for the Yukawa couplings. The implications of this parametrization for unification of the Yukawa couplings are also explored.

  10. Years of life lost due to influenza-attributable mortality in older adults in the Netherlands: a competing risks approach.

    PubMed

    McDonald, Scott A; van Wijhe, Maarten; van Asten, Liselotte; van der Hoek, Wim; Wallinga, Jacco

    2018-02-06

    We estimated the influenza mortality burden in adults 60 years of age and older in the Netherlands in terms of years of life lost, taking into account competing mortality risks. Weekly laboratory surveillance data for influenza and other respiratory pathogens and weekly extreme temperature served as covariates in Poisson regression models fitted to weekly age-group specific mortality data for the period 1999/2000 through 2012/13. Burden for age-groups 60-64 through 85-89 years was computed as years of life lost before age 90 (YLL90) using restricted mean lifetimes survival analysis and accounting for competing risks. Influenza-attributable mortality burden was greatest for persons aged 80-84 years, at 914 YLL90 per 100,000 persons (95% uncertainty interval:867, 963), followed by 85-89 years (787 YLL90/100,000; 95% uncertainty interval:741, 834). Ignoring competing mortality risks in the computation of influenza-attributable YLL90 would lead to substantial over-estimation of burden, from 3.5% for 60-64 years to 82% for persons aged 80-89 years at death. Failure to account for competing mortality risks has implications for accuracy of disease burden estimates, especially among persons aged 80 years and older. As the mortality burden borne by the elderly is notably high, prevention initiatives may benefit from being redesigned to more effectively prevent infection in the oldest age-groups. © The Author(s) 2018. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Conceptualization and Pilot Testing of a Core Competency-Based Training Workshop in Suicide Risk Assessment and Management: Notes From the Field.

    PubMed

    Cramer, Robert J; Bryson, Claire N; Eichorst, Morgam K; Keyes, Lee N; Ridge, Brittany E

    2017-03-01

    As professional psychology training programs and continuing education have moved toward competency based approaches, it has become equally important to develop uniform, evidence-based approaches for suicide risk assessment and management. The present article presents a workshop curriculum based on established core competencies in suicide risk assessment and management. Drawing on theories suicide risk formation, the workshop features an integration of didactic, process, and experiential components. We present pilot data from 2 small group workshops (n = 17): 1 from a clinical psychology doctoral program and 1 from a university counseling center. Workshop participation yielded increases in (a) the ability to recognize appropriate clinician responses to suicidal client statements, (b) self-perceptions of general capacity to interface with suicidal patients and mastery of the 10 core competencies, (c) factual knowledge concerning suicide risk assessment and management, and (d) the self-rated ability to assess and manage a suicidal patient. We discuss statistical and generalizability limitations as well as implications for future modification, implementation, and provision of this training method. © 2016 Wiley Periodicals, Inc.

  12. Intern Boot Camp: Feasibility and impact of a 1-hour session to ensure graduating medical student competency in falls risk assessment.

    PubMed

    Omlor, Rebecca L; Watkins, Franklin S; Lawlor, Janice S; Lovato, James F; Fino, Nora F; Atkinson, Hal H

    2017-01-01

    The authors evaluated the feasibility of a 1-hour session to ensure competency in gait and falls risk assessment for medical students at their institution. The session included a history and exam with faculty and staff as standardized patients, gait recognition videos, and case evaluation for falls risk assessment and prevention. Student perceptions were evaluated using a retrospective pre-post survey, scored on a 5-point Likert-type scale. Wilcoxon signed-rank tests were used to assess change and Kruskal-Wallis tests were used to analyze differences by residency choice. A range of five to 11 faculty and staff certified 238 medical students during eight 1-hour sessions. Overall self-perception of competence in falls risk assessment and prevention improved (p ≤ .001), and did not differ by residency choice, both before and after the training program (p = .73 and p = .25). Feedback was positive. This session is a feasible way to teach and assess the competency for falls risk assessment with modest time commitment.

  13. Combined non-parametric and parametric approach for identification of time-variant systems

    NASA Astrophysics Data System (ADS)

    Dziedziech, Kajetan; Czop, Piotr; Staszewski, Wieslaw J.; Uhl, Tadeusz

    2018-03-01

    Identification of systems, structures and machines with variable physical parameters is a challenging task especially when time-varying vibration modes are involved. The paper proposes a new combined, two-step - i.e. non-parametric and parametric - modelling approach in order to determine time-varying vibration modes based on input-output measurements. Single-degree-of-freedom (SDOF) vibration modes from multi-degree-of-freedom (MDOF) non-parametric system representation are extracted in the first step with the use of time-frequency wavelet-based filters. The second step involves time-varying parametric representation of extracted modes with the use of recursive linear autoregressive-moving-average with exogenous inputs (ARMAX) models. The combined approach is demonstrated using system identification analysis based on the experimental mass-varying MDOF frame-like structure subjected to random excitation. The results show that the proposed combined method correctly captures the dynamics of the analysed structure, using minimum a priori information on the model.

  14. Prepositioning emergency supplies under uncertainty: a parametric optimization method

    NASA Astrophysics Data System (ADS)

    Bai, Xuejie; Gao, Jinwu; Liu, Yankui

    2018-07-01

    Prepositioning of emergency supplies is an effective method for increasing preparedness for disasters and has received much attention in recent years. In this article, the prepositioning problem is studied by a robust parametric optimization method. The transportation cost, supply, demand and capacity are unknown prior to the extraordinary event, which are represented as fuzzy parameters with variable possibility distributions. The variable possibility distributions are obtained through the credibility critical value reduction method for type-2 fuzzy variables. The prepositioning problem is formulated as a fuzzy value-at-risk model to achieve a minimum total cost incurred in the whole process. The key difficulty in solving the proposed optimization model is to evaluate the quantile of the fuzzy function in the objective and the credibility in the constraints. The objective function and constraints can be turned into their equivalent parametric forms through chance constrained programming under the different confidence levels. Taking advantage of the structural characteristics of the equivalent optimization model, a parameter-based domain decomposition method is developed to divide the original optimization problem into six mixed-integer parametric submodels, which can be solved by standard optimization solvers. Finally, to explore the viability of the developed model and the solution approach, some computational experiments are performed on realistic scale case problems. The computational results reported in the numerical example show the credibility and superiority of the proposed parametric optimization method.

  15. Parametric Cooling of Ultracold Atoms

    NASA Astrophysics Data System (ADS)

    Boguslawski, Matthew; Bharath, H. M.; Barrios, Maryrose; Chapman, Michael

    2017-04-01

    An oscillator is characterized by a restoring force which determines the natural frequency at which oscillations occur. The amplitude and phase-noise of these oscillations can be amplified or squeezed by modulating the magnitude of this force (e.g. the stiffness of the spring) at twice the natural frequency. This is parametric excitation; a long-studied phenomena in both the classical and quantum regimes. Parametric cooling, or the parametric squeezing of thermo-mechanical noise in oscillators has been studied in micro-mechanical oscillators and trapped ions. We study parametric cooling in ultracold atoms. This method shows a modest reduction of the variance of atomic momenta, and can be easily employed with pre-existing controls in many experiments. Parametric cooling is comparable to delta-kicked cooling, sharing similar limitations. We expect this cooling to find utility in microgravity experiments where the experiment duration is limited by atomic free expansion.

  16. Parametric versus Cox's model: an illustrative analysis of divorce in Canada.

    PubMed

    Balakrishnan, T R; Rao, K V; Krotki, K J; Lapierre-adamcyk, E

    1988-06-01

    Recent demographic literature clearly recognizes the importance of survival modes in the analysis of cross-sectional event histories. Of the various survival models, Cox's (1972) partial parametric model has been very popular due to its simplicity, and readily available computer software for estimation, sometimes at the cost of precision and parsimony of the model. This paper focuses on parametric failure time models for event history analysis such as Weibell, lognormal, loglogistic, and exponential models. The authors also test the goodness of fit of these parametric models versus the Cox's proportional hazards model taking Kaplan-Meier estimate as base. As an illustration, the authors reanalyze the Canadian Fertility Survey data on 1st marriage dissolution with parametric models. Though these parametric model estimates were not very different from each other, there seemed to be a slightly better fit with loglogistic. When 8 covariates were used in the analysis, it was found that the coefficients were similar in the models, and the overall conclusions about the relative risks would not have been different. The findings reveal that in marriage dissolution, the differences according to demographic and socioeconomic characteristics may be far more important than is generally found in many studies. Therefore, one should not treat the population as homogeneous in analyzing survival probabilities of marriages, other than for cursory analysis of overall trends.

  17. Associations between eating competence and cardiovascular disease biomarkers.

    PubMed

    Psota, Tricia L; Lohse, Barbara; West, Sheila G

    2007-01-01

    Explore the relationship between eating competence (EC) and biomarkers of risk for cardiovascular disease (CVD). Secondary analysis of data collected for a larger, 2-way crossover clinical trial. Outpatient clinical research center. Forty-eight hypercholesterolemic (LDL cholesterol > or = 110 mg/dL) men (n = 19) and women (n = 29) 21 to 70 years of age. Participant descriptives, cardiovascular disease biomarker levels, and eating competence (EC) determined by the ecSatter Inventory (ecSI). T tests for differences in eating competence between males and females, analysis of variance for differences in risk between those categorized as EC or not. Associations between EC and baseline biochemical measures, as well as participant characteristics and dietary intake, were assessed by Pearson correlation analyses. Logistic regression estimated relative risk of CVD risk factors from ecSI scores. Several significant associations were found between EC total and CVD risk factors. Eating competence was positively correlated with HDL-cholesterol, and inversely associated with systolic and diastolic blood pressure. High EC participants had significantly lower ratios of total cholesterol: HDL-cholesterol and triglycerides: HDL-cholesterol. Participants who were not eating competent were 5 times more likely to have LDL-cholesterol levels > or =130 mg/dL and 7 times more likely to have triglyceride levels > or =150 mg/dL. Eating competence appears to be a cognitive, affective construct with physiological manifestations, making nutrition education to increase eating competence a medical nutrition therapy.

  18. 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 Central

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

    2015-01-01

    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

  19. A survey of risk factors for digit injuries among dogs training and competing in agility events.

    PubMed

    Sellon, Debra C; Martucci, Katherine; Wenz, John R; Marcellin-Little, Denis J; Powers, Michelle; Cullen, Kimberley L

    2018-01-01

    OBJECTIVE To identify potential risk factors for digit injuries in dogs training and competing in agility events. DESIGN Internet-based, retrospective, cross-sectional survey. ANIMALS 1,081 dogs training or competing in agility events. PROCEDURES Data were collected for eligible animals via retrospective surveys distributed electronically to handlers of dogs participating in agility-related activities. Variables evaluated included demographic (handlers) and signalment (dogs) information, physical characteristics of dogs, and injury characteristics. A separate survey of dogs competing in similar agility-related activities but without digit injuries was also administered. Multivariable logistic regression was used to develop a model for assessment of risk factors. RESULTS Data were collected from 207 agility dogs with digit injuries and 874 agility dogs without digit injuries. Factors associated with significantly increased odds of injury included Border Collie breed (OR, 2.3; 95% confidence interval [CI], 1.5 to 3.3), long nails (OR, 2.4; 95% CI, 1.3 to 4.5), absence of front dewclaws (OR, 1.9; 95% CI, 1.3 to 2.6), and greater weight-to-height ratio (OR, 1.5; 95% CI, 1.1 to 2.0). Odds of injury decreased with increasing age of the dog (OR, 0.8; 95% CI, 0.76 to 0.86). CONCLUSIONS AND CLINICAL RELEVANCE Results should be cautiously interpreted because of potential respondent and recall bias and lack of review of medical records. Nevertheless, results suggested that retaining healthy dewclaws, maintaining lean body mass, and trimming nails short for training and competition may decrease the likelihood of digit injuries. Research to investigate training practices, obstacle construction specifcations, and surface considerations for dogs competing in agility activities is indicated.

  20. A Parametric k-Means Algorithm

    PubMed Central

    Tarpey, Thaddeus

    2007-01-01

    Summary The k points that optimally represent a distribution (usually in terms of a squared error loss) are called the k principal points. This paper presents a computationally intensive method that automatically determines the principal points of a parametric distribution. Cluster means from the k-means algorithm are nonparametric estimators of principal points. A parametric k-means approach is introduced for estimating principal points by running the k-means algorithm on a very large simulated data set from a distribution whose parameters are estimated using maximum likelihood. Theoretical and simulation results are presented comparing the parametric k-means algorithm to the usual k-means algorithm and an example on determining sizes of gas masks is used to illustrate the parametric k-means algorithm. PMID:17917692

  1. Study of parametric instability in gravitational wave detectors with silicon test masses

    NASA Astrophysics Data System (ADS)

    Zhang, Jue; Zhao, Chunnong; Ju, Li; Blair, David

    2017-03-01

    Parametric instability is an intrinsic risk in high power laser interferometer gravitational wave detectors, in which the optical cavity modes interact with the acoustic modes of the mirrors, leading to exponential growth of the acoustic vibration. In this paper, we investigate the potential parametric instability for a proposed next generation gravitational wave detector, the LIGO Voyager blue design, with cooled silicon test masses of size 45 cm in diameter and 55 cm in thickness. It is shown that there would be about two unstable modes per test mass at an arm cavity power of 3 MW, with the highest parametric gain of  ∼76. While this is less than the predicted number of unstable modes for Advanced LIGO (∼40 modes with max gain of  ∼32 at the designed operating power of 830 kW), the importance of developing suitable instability suppression schemes is emphasized.

  2. Competing risk of atherosclerotic risk factors for arterial and venous thrombosis in a general population: the Tromso study.

    PubMed

    Brækkan, Sigrid K; Hald, Erin M; Mathiesen, Ellisiv B; Njølstad, Inger; Wilsgaard, Tom; Rosendaal, Frits R; Hansen, John-Bjarne

    2012-02-01

    To investigate and compare the impact of traditional atherosclerotic risk factors for the risk of arterial and venous thrombosis, taking into account competing risks. In 1994-1995, 26,185 subjects were screened in the Tromsø study. Information on traditional atherosclerotic risk factors was obtained by physical examination, blood samples, and questionnaires. Subjects were followed to the first incident event of myocardial infarction (MI) or venous thromboembolism (VTE), or December 31, 2005. During a median of 10.8 years of follow-up, there were 1279 cases of incident MI and 341 VTE events. Advancing age and high body mass index were both associated with MI and VTE. Hazard ratio per decade of age was 2.34 (95% CI: 2.25-2.43) for MI and 1.87 (1.74-2.01) for VTE, and 3 kg/m(2) increase in body mass index was associated with 1.16 (1.11-1.21) and 1.20 (1.12-1.29) increased risk of MI and VTE, respectively. Blood pressure, high levels of triglycerides and total cholesterol, low HDL cholesterol, self-reported diabetes, and smoking were all associated with increased risk of MI but not associated with VTE. Our findings imply that traditional atherosclerotic risk factors, such as smoking, hypertension, dyslipidemia, and diabetes mellitus are not shared by arterial and venous thrombosis.

  3. Long-range parametric amplification of THz wave with absorption loss exceeding parametric gain.

    PubMed

    Wang, Tsong-Dong; Huang, Yen-Chieh; Chuang, Ming-Yun; Lin, Yen-Hou; Lee, Ching-Han; Lin, Yen-Yin; Lin, Fan-Yi; Kitaeva, Galiya Kh

    2013-01-28

    Optical parametric mixing is a popular scheme to generate an idler wave at THz frequencies, although the THz wave is often absorbing in the nonlinear optical material. It is widely suggested that the useful material length for co-directional parametric mixing with strong THz-wave absorption is comparable to the THz-wave absorption length in the material. Here we show that, even in the limit of the absorption loss exceeding parametric gain, the THz idler wave can grows monotonically from optical parametric amplification over a much longer distance in a nonlinear optical material until pump depletion. The coherent production of the non-absorbing signal wave can assist the growth of the highly absorbing idler wave. We also show that, for the case of an equal input pump and signal in difference frequency generation, the quick saturation of the THz idler wave predicted from a much simplified and yet popular plane-wave model fails when fast diffraction of the THz wave from the co-propagating optical mixing waves is considered.

  4. 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. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Observing and Planning for Play and Competence.

    ERIC Educational Resources Information Center

    Neumann, Eva A.

    This paper presents a framework useful for preschool and elementary teachers in developing a basic understanding of competency and play and their interrelationship. Specific guidelines are given for observing and planning toward increasing opportunities for competency and play. Competency is viewed as consisting of growth, risk-taking, and a…

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

    PubMed

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

    2015-01-01

    To determine connections between competence, usability, environment and risk of falls in elderly adults. 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. 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. This study helps to better understand the phenomenon of falling, to find a connection between usability with the risk of falls, and other variables.

  7. 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

  8. Hyperbolic and semi-parametric models in finance

    NASA Astrophysics Data System (ADS)

    Bingham, N. H.; Kiesel, Rüdiger

    2001-02-01

    The benchmark Black-Scholes-Merton model of mathematical finance is parametric, based on the normal/Gaussian distribution. Its principal parametric competitor, the hyperbolic model of Barndorff-Nielsen, Eberlein and others, is briefly discussed. Our main theme is the use of semi-parametric models, incorporating the mean vector and covariance matrix as in the Markowitz approach, plus a non-parametric part, a scalar function incorporating features such as tail-decay. Implementation is also briefly discussed.

  9. 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

  10. Emotional competence and online game use in adolescents.

    PubMed

    Seo, Mia; Kang, Hee Sun; Chae, Sun-Mi

    2012-12-01

    The purpose of this study was to explore the relations between emotional competence and online game use in adolescents. This study is a cross-sectional descriptive survey using a convenience sample. The participants were 2199 adolescents in South Korea. Online game use and emotional competence including positive emotion, emotional expression, and emotional intelligence were measured. The study results indicated that emotional competence was negatively correlated with excessive online game use. All variables of emotional competence were significantly lower in high-risk users compared with general users. In addition, female adolescents were rated significantly higher in emotional competence among general users, but there were no significant gender differences among high-risk users. The results of our study imply that high-risk game users have lower levels of emotional intelligence than general users do. The results of this study suggest that emotion is an important factor to which practitioners in psychomedical fields and nursing should pay attention. Therefore, nurses in schools and communities should regularly screen the emotions of adolescents who habitually play online games and develop a program to enhance emotional competence associated with online games.

  11. 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…

  12. Parametric resonance in tunable superconducting cavities

    NASA Astrophysics Data System (ADS)

    Wustmann, Waltraut; Shumeiko, Vitaly

    2013-05-01

    We develop a theory of parametric resonance in tunable superconducting cavities. The nonlinearity introduced by the superconducting quantum interference device (SQUID) attached to the cavity and damping due to connection of the cavity to a transmission line are taken into consideration. We study in detail the nonlinear classical dynamics of the cavity field below and above the parametric threshold for the degenerate parametric resonance, featuring regimes of multistability and parametric radiation. We investigate the phase-sensitive amplification of external signals on resonance, as well as amplification of detuned signals, and relate the amplifier performance to that of linear parametric amplifiers. We also discuss applications of the device for dispersive qubit readout. Beyond the classical response of the cavity, we investigate small quantum fluctuations around the amplified classical signals. We evaluate the noise power spectrum both for the internal field in the cavity and the output field. Other quantum-statistical properties of the noise are addressed such as squeezing spectra, second-order coherence, and two-mode entanglement.

  13. Why preferring parametric forecasting to nonparametric methods?

    PubMed

    Jabot, Franck

    2015-05-07

    A recent series of papers by Charles T. Perretti and collaborators have shown that nonparametric forecasting methods can outperform parametric methods in noisy nonlinear systems. Such a situation can arise because of two main reasons: the instability of parametric inference procedures in chaotic systems which can lead to biased parameter estimates, and the discrepancy between the real system dynamics and the modeled one, a problem that Perretti and collaborators call "the true model myth". Should ecologists go on using the demanding parametric machinery when trying to forecast the dynamics of complex ecosystems? Or should they rely on the elegant nonparametric approach that appears so promising? It will be here argued that ecological forecasting based on parametric models presents two key comparative advantages over nonparametric approaches. First, the likelihood of parametric forecasting failure can be diagnosed thanks to simple Bayesian model checking procedures. Second, when parametric forecasting is diagnosed to be reliable, forecasting uncertainty can be estimated on virtual data generated with the fitted to data parametric model. In contrast, nonparametric techniques provide forecasts with unknown reliability. This argumentation is illustrated with the simple theta-logistic model that was previously used by Perretti and collaborators to make their point. It should convince ecologists to stick to standard parametric approaches, until methods have been developed to assess the reliability of nonparametric forecasting. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Risk Management. Unit 20. Level 1. Instructor Guide. PACE: Program for Acquiring Competence in Entrepreneurship. Third Edition. Research & Development Series No. 301-20.

    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 1 of learning--understanding…

  15. Parametric instability of shaft with discs

    NASA Astrophysics Data System (ADS)

    Wahab, A. M. Abdul; Rasid, Z. A.; Abu, A.; Rudin, N. F. Mohd Noor

    2017-12-01

    The occurrence of resonance is a major criterion to be considered in the design of shaft. While force resonance occurs merely when the natural frequency of the rotor system equals speed of the shaft, parametric resonance or parametric instability can occur at excitation speed that is integral or sub-multiple of the frequency of the rotor. This makes the study on parametric resonance crucial. Parametric instability of a shaft system consisting of a shaft and disks has been investigated in this study. The finite element formulation of the Mathieu-Hill equation that represents the parametric instability problem of the shaft is developed based on Timoshenko’s beam theory and Nelson’s finite element method (FEM) model that considers the effect of torsional motion on such problem. The Bolotin’s method is used to determine the regions of instability and the Strut-Ince diagram. The validation works show that the results of this study are in close agreement to past results. It is found that a larger radius of disk will cause the shaft to become more unstable compared to smaller radius although both weights are similar. Furthermore, the effect of torsional motion on the parametric instability of the shaft is significant at higher rotating speed.

  16. Parametric nanomechanical amplification at very high frequency.

    PubMed

    Karabalin, R B; Feng, X L; Roukes, M L

    2009-09-01

    Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.

  17. Parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method of ledre profile attributes

    NASA Astrophysics Data System (ADS)

    Hastuti, S.; Harijono; Murtini, E. S.; Fibrianto, K.

    2018-03-01

    This current study is aimed to investigate the use of parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method. Ledre as Bojonegoro unique local food product was used as point of interest, in which 319 panelists were involved in the study. The result showed that ledre is characterized as easy-crushed texture, sticky in mouth, stingy sensation and easy to swallow. It has also strong banana flavour with brown in colour. Compared to eggroll and semprong, ledre has more variances in terms of taste as well the roll length. As RATA questionnaire is designed to collect categorical data, non-parametric approach is the common statistical procedure. However, similar results were also obtained as parametric approach, regardless the fact of non-normal distributed data. Thus, it suggests that parametric approach can be applicable for consumer study with large number of respondents, even though it may not satisfy the assumption of ANOVA (Analysis of Variances).

  18. 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.

  19. Multibeam Formation with a Parametric Sonar

    DTIC Science & Technology

    1976-03-05

    AD-A022 815 MULTIBEAM FORMATION WITH A PARAMETRIC SONAR Robert L. White Texas University at Austin Prepared for: Office of Naval Research 5 March...PARAMETRIC SONAR Final Report under Contract N00014-70-A-0166, Task 0020 1 February - 31 July 1974 Robe&, L. White OFFICE OF NAVAL RESEARCH Contract N00014...78712 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. r-X: ~ ... ABSTRACT Parametric sonar has proven to be an effective concept in sonar

  20. Diet-Induced Overweight and Obesity and Periodontitis Risk: An Application of the Parametric G-Formula in the 1982 Pelotas Birth Cohort.

    PubMed

    Nascimento, Gustavo G; Peres, Marco A; Mittinty, Murthy N; Peres, Karen G; Do, Loc G; Horta, Bernardo L; Gigante, Denise P; Corrêa, Marcos B; Demarco, Flávio F

    2017-03-15

    We aimed to estimate hypothetical effects of habits (smoking, alcohol consumption, and fat and carbohydrates consumption) combined with diet-induced overweight/obesity on the risk of periodontitis. The risk of any periodontitis, moderate/severe periodontitis, and the combination of bleeding on probing (BOP) and clinical attachment loss (CAL) was estimated using the parametric g-formula in adults aged 31 years from the 1982 Pelotas Birth Cohort in Brazil. Individuals in this cohort have been followed since birth. Hypothetical conditions were set independently for each risk factor and in combination for the entire population. A total of 539 participants had oral examinations in 2013. The cumulative 31-year risk under no intervention was 33.3% for any periodontitis, 14.3%, for moderate/severe periodontitis, and 14.7%, for BOP and CAL. According to our statistical approach, diet-induced overweight/obesity increased the risk of all outcomes: 11% (overweight) and 22% (obesity) higher risk of periodontitis; 12% (overweight) and 27% (obesity) higher risk of moderate/severe periodontitis; 21% (overweight) and 57% (obesity) higher risk of CAL and BOP. When overweight/obesity was combined with other unhealthy habits, the risk was even greater. Our findings suggest that the combination of diet-induced obesity with other risk factors may increase the risk of periodontitis. Further research in the field is required to corroborate our study. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. 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.

  2. 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.

  3. 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.

  4. 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…

  5. Lifetime competing risks between coronary heart disease mortality and other causes of death during 50years of follow-up.

    PubMed

    Puddu, Paolo Emilio; Piras, Paolo; Menotti, Alessandro

    2017-02-01

    To study coronary heart disease (CHD) death versus 11 other causes of death using the cumulative incidence function (CIF) and the competing risks procedures to disentangle the differential role of risk factors for different end-points. Standard Cox and Fine-Gray models among 1712 middle-aged men were compared during 50years of follow-up. CHD death was the primary event, while deaths from 11 selected causes, mutually exclusive from the primary end-point, were considered as secondary events. Reverse solutions were also performed. We considered 10 selected risk factors. CHD death risk was the second highest among 12 mostly specific causes of death. Some risk factors were specific: serum cholesterol for CHD death whereas, systolic blood pressure, cigarette smoking and age may have a differential role in other causes of death. Application of the Fine-Gray model based on CIF enabled to dissect, at least in part, the respective role that baseline covariates may have to segregate the probabilities of two types of death in contrast from each other. They also point to the absence of contributing significance for some of the selected risk factors and this calls for a parsimonious approach in predictions. The relative rarity of competing risk challenges when defining the risk factors role at long-term needs now be corrected since we have clearly shown, with Fine-Gray model, at direct or reverse use, that comparing different end-points heavily influences the risk factor predictive capacity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Slow Gait Speed and Risk of Long-Term Nursing Home Residence in Older Women, Adjusting for Competing Risk of Mortality: Results from the Study of Osteoporotic Fractures.

    PubMed

    Lyons, Jennifer G; Ensrud, Kristine E; Schousboe, John T; McCulloch, Charles E; Taylor, Brent C; Heeren, Timothy C; Stuver, Sherri O; Fredman, Lisa

    2016-12-01

    To determine whether slow gait speed increases the risk of costly long-term nursing home residence when accounting for death as a competing risk remains unknown. Longitudinal cohort study using proportional hazards models to predict long-term nursing home residence and subdistribution models with death as a competing risk. Community-based prospective cohort study. Older women (mean age 76.3) participating in the Study of Osteoporotic Fractures who were also enrolled in Medicare fee-for-service plans (N = 3,755). Gait speed was measured on a straight 6-m course and averaged over two trials. Long-term nursing home residence was defined using a validated algorithm based on Medicare Part B claims for nursing home-related care. Participants were followed until long-term nursing home residence, disenrollment from Medicare plan, death, or December 31, 2010. Over the follow-up period (median 11 years), 881 participants (23%) experienced long-term nursing home residence, and 1,013 (27%) died before experiencing this outcome. Slow walkers (55% of participants with gait speed <1 m/s) were significantly more likely than fast walkers to reside in a nursing home long-term (adjusted hazards ratio (aHR) = 1.79, 95% confidence interval (CI) = 1.54-2.09). Associations were attenuated in subdistribution models (aHR = 1.52, 95% CI = 1.30-1.77) but remained statistically significant. Older community-dwelling women with slow gait speed are more likely to experience long-term nursing home residence, as well as mortality without long-term residence. Ignoring the competing mortality risk may overestimate long-term care needs and costs. © 2016, Copyright the Authors Journal compilation © 2016, The American Geriatrics Society.

  7. Competing approaches to analysis of failure times with competing risks.

    PubMed

    Farley, T M; Ali, M M; Slaymaker, E

    2001-12-15

    For the analysis of time to event data in contraceptive studies when individuals are subject to competing causes for discontinuation, some authors have recently advocated the use of the cumulative incidence rate as a more appropriate measure to summarize data than the complement of the Kaplan-Meier estimate of discontinuation. The former method estimates the rate of discontinuation in the presence of competing causes, while the latter is a hypothetical rate that would be observed if discontinuations for the other reasons could not occur. The difference between the two methods of analysis is the continuous time equivalent of a debate that took place in the contraceptive literature in the 1960s, when several authors advocated the use of net (adjusted or single decrement life table rates) rates in preference to crude rates (multiple decrement life table rates). A small simulation study illustrates the interpretation of the two types of estimate - the complement of the Kaplan-Meier estimate corresponds to a hypothetical rate where discontinuations for other reasons did not occur, while the cumulative incidence gives systematically lower estimates. The Kaplan-Meier estimates are more appropriate when estimating the effectiveness of a contraceptive method, but the cumulative incidence estimates are more appropriate when making programmatic decisions regarding contraceptive methods. Other areas of application, such as cancer studies, may prefer to use the cumulative incidence estimates, but their use should be determined according to the application. Copyright 2001 John Wiley & Sons, Ltd.

  8. Repeated testing improves achievement in a blended learning approach for risk competence training of medical students: results of a randomized controlled trial.

    PubMed

    Spreckelsen, C; Juenger, J

    2017-09-26

    Adequate estimation and communication of risks is a critical competence of physicians. Due to an evident lack of these competences, effective training addressing risk competence during medical education is needed. Test-enhanced learning has been shown to produce marked effects on achievements. This study aimed to investigate the effect of repeated tests implemented on top of a blended learning program for risk competence. We introduced a blended-learning curriculum for risk estimation and risk communication based on a set of operationalized learning objectives, which was integrated into a mandatory course "Evidence-based Medicine" for third-year students. A randomized controlled trial addressed the effect of repeated testing on achievement as measured by the students' pre- and post-training score (nine multiple-choice items). Basic numeracy and statistical literacy were assessed at baseline. Analysis relied on descriptive statistics (histograms, box plots, scatter plots, and summary of descriptive measures), bootstrapped confidence intervals, analysis of covariance (ANCOVA), and effect sizes (Cohen's d, r) based on adjusted means and standard deviations. All of the 114 students enrolled in the course consented to take part in the study and were assigned to either the intervention or control group (both: n = 57) by balanced randomization. Five participants dropped out due to non-compliance (control: 4, intervention: 1). Both groups profited considerably from the program in general (Cohen's d for overall pre vs. post scores: 2.61). Repeated testing yielded an additional positive effect: while the covariate (baseline score) exhibits no relation to the post-intervention score, F(1, 106) = 2.88, p > .05, there was a significant effect of the intervention (repeated tests scenario) on learning achievement, F(1106) = 12.72, p < .05, d = .94, r = .42 (95% CI: [.26, .57]). However, in the subgroup of participants with a high initial numeracy score no similar

  9. Phase noise suppression through parametric filtering

    NASA Astrophysics Data System (ADS)

    Cassella, Cristian; Strachan, Scott; Shaw, Steven W.; Piazza, Gianluca

    2017-02-01

    In this work, we introduce and experimentally demonstrate a parametric phase noise suppression technique, which we call "parametric phase noise filtering." This technique is based on the use of a solid-state parametric amplifier operating in its instability region and included in a non-autonomous feedback loop connected at the output of a noisy oscillator. We demonstrate that such a system behaves as a parametrically driven Duffing resonator and can operate at special points where it becomes largely immune to the phase fluctuations that affect the oscillator output signal. A prototype of a parametric phase noise filter (PFIL) was designed and fabricated to operate in the very-high-frequency range. The PFIL prototype allowed us to significantly reduce the phase noise at the output of a commercial signal generator operating around 220 MHz. Noise reduction of 16 dB (40×) and 13 dB (20×) were obtained, respectively, at 1 and 10 kHz offsets from the carrier frequency. The demonstration of this phase noise suppression technique opens up scenarios in the development of passive and low-cost phase noise cancellation circuits for any application demanding high quality frequency generation.

  10. Competing risk models in reliability systems, an exponential distribution model with Bayesian analysis approach

    NASA Astrophysics Data System (ADS)

    Iskandar, I.

    2018-03-01

    The exponential distribution is the most widely used reliability analysis. This distribution is very suitable for representing the lengths of life of many cases and is available in a simple statistical form. The characteristic of this distribution is a constant hazard rate. The exponential distribution is the lower rank of the Weibull distributions. In this paper our effort is to introduce the basic notions that constitute an exponential competing risks model in reliability analysis using Bayesian analysis approach and presenting their analytic methods. The cases are limited to the models with independent causes of failure. A non-informative prior distribution is used in our analysis. This model describes the likelihood function and follows with the description of the posterior function and the estimations of the point, interval, hazard function, and reliability. The net probability of failure if only one specific risk is present, crude probability of failure due to a specific risk in the presence of other causes, and partial crude probabilities are also included.

  11. Self-seeding ring optical parametric oscillator

    DOEpatents

    Smith, Arlee V [Albuquerque, NM; Armstrong, Darrell J [Albuquerque, NM

    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.

  12. Parametric amplification in MoS2 drum resonator.

    PubMed

    Prasad, Parmeshwar; Arora, Nishta; Naik, A K

    2017-11-30

    Parametric amplification is widely used in diverse areas from optics to electronic circuits to enhance low level signals by varying relevant system parameters. Parametric amplification has also been performed in several micro-nano resonators including nano-electromechanical system (NEMS) resonators based on a two-dimensional (2D) material. Here, we report the enhancement of mechanical response in a MoS 2 drum resonator using degenerate parametric amplification. We use parametric pumping to modulate the spring constant of the MoS 2 resonator and achieve a 10 dB amplitude gain. We also demonstrate quality factor enhancement in the resonator with parametric amplification. We investigate the effect of cubic nonlinearity on parametric amplification and show that it limits the gain of the mechanical resonator. Amplifying ultra-small displacements at room temperature and understanding the limitations of the amplification in these devices is key for using these devices for practical applications.

  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. EI competencies as a related but different characteristic than intelligence

    PubMed Central

    Boyatzis, Richard E.; Batista-Foguet, Joan M.; Fernández-i-Marín, Xavier; Truninger, Margarida

    2015-01-01

    Amid the swarm of debate about emotional intelligence (EI) among academics are claims that cognitive intelligence, or general mental ability (g), is a stronger predictor of life and work outcomes as well as the counter claims that EI is their strongest predictor. Nested within the tempest in a teapot are scientific questions as to what the relationship is between g and EI. Using a behavioral approach to EI, we examined the relationship of a parametric measure of g as the person’s GMAT scores and collected observations from others who live and work with the person as to the frequency of his or her EI behavior, as well as the person’s self-assessment. The results show that EI, as seen by others, is slightly related to g, especially for males with assessment from professional relations. Further, we found that cognitive competencies are more strongly related to GMAT than EI competencies. For observations from personal relationships or self-assessment, there is no relationship between EI and GMAT. Observations from professional relations reveal a positive relationship between cognitive competencies and GMAT and EI and GMAT for males, but a negative relationship between EI and GMAT for females. PMID:25713545

  15. EI competencies as a related but different characteristic than intelligence.

    PubMed

    Boyatzis, Richard E; Batista-Foguet, Joan M; Fernández-I-Marín, Xavier; Truninger, Margarida

    2015-01-01

    Amid the swarm of debate about emotional intelligence (EI) among academics are claims that cognitive intelligence, or general mental ability (g), is a stronger predictor of life and work outcomes as well as the counter claims that EI is their strongest predictor. Nested within the tempest in a teapot are scientific questions as to what the relationship is between g and EI. Using a behavioral approach to EI, we examined the relationship of a parametric measure of g as the person's GMAT scores and collected observations from others who live and work with the person as to the frequency of his or her EI behavior, as well as the person's self-assessment. The results show that EI, as seen by others, is slightly related to g, especially for males with assessment from professional relations. Further, we found that cognitive competencies are more strongly related to GMAT than EI competencies. For observations from personal relationships or self-assessment, there is no relationship between EI and GMAT. Observations from professional relations reveal a positive relationship between cognitive competencies and GMAT and EI and GMAT for males, but a negative relationship between EI and GMAT for females.

  16. An improvement of quantum parametric methods by using SGSA parameterization technique and new elementary parametric functionals

    NASA Astrophysics Data System (ADS)

    Sánchez, M.; Oldenhof, M.; Freitez, J. A.; Mundim, K. C.; Ruette, F.

    A systematic improvement of parametric quantum methods (PQM) is performed by considering: (a) a new application of parameterization procedure to PQMs and (b) novel parametric functionals based on properties of elementary parametric functionals (EPF) [Ruette et al., Int J Quantum Chem 2008, 108, 1831]. Parameterization was carried out by using the simplified generalized simulated annealing (SGSA) method in the CATIVIC program. This code has been parallelized and comparison with MOPAC/2007 (PM6) and MINDO/SR was performed for a set of molecules with C=C, C=H, and H=H bonds. Results showed better accuracy than MINDO/SR and MOPAC-2007 for a selected trial set of molecules.

  17. Current risks of HeartMate II pump thrombosis: Non-parametric analysis of Interagency Registry for Mechanically Assisted Circulatory Support data.

    PubMed

    Smedira, Nicholas G; Blackstone, Eugene H; Ehrlinger, John; Thuita, Lucy; Pierce, Christopher D; Moazami, Nader; Starling, Randall C

    2015-12-01

    Data from 3 institutions revealed an abrupt increase in HeartMate II (Thoratec) pump thrombosis starting in 2011, associated with 48% mortality at 6 months without transplantation or pump exchange. We sought to discover if the increase occurred nationwide in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) data, and if so (1) determine if accelerated risk continued, (2) identify predictors, (3) investigate institutional variability, and (4) assess mortality after pump thrombosis. From April 2008 to June 2014, 11,123 HeartMate II devices were implanted at 146 institutions. Machine learning, non-parametric Random Forests for Survival was used to explore risk-adjusted thrombosis based on 87 pre-implant and implant variables, including implant date. A total of 995 pumps thrombosed, with risk peaking within weeks of implant. The risk-adjusted increase in pump thrombosis began in 2010, reached a maximum in 2012, and then plateaued at a level that was 3.3-times higher than pre-2010. Pump exchange, younger age, and larger body mass index were important predictors, and institutional variability was largely explained by implant date, patient profile, and duration of support. The probability of death within 3 months after pump thrombosis was 24%. Accelerated risk of HeartMate II thrombosis was confirmed by Interagency Registry for Mechanically Assisted Circulatory Support data, with risk subsequently leveling at a risk-adjusted rate higher than observed pre-2010. This elevated thrombosis risk emphasizes the need for improved mechanical circulatory support systems and post-market surveillance of adverse events. Clinicians cognizant of these new data should incorporate them into their and their patients' expectations and understanding of risks relative to those of transplantation and continued medical therapy. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  18. Grating lobe elimination in steerable parametric loudspeaker.

    PubMed

    Shi, Chuang; Gan, Woon-Seng

    2011-02-01

    In the past two decades, the majority of research on the parametric loudspeaker has concentrated on the nonlinear modeling of acoustic propagation and pre-processing techniques to reduce nonlinear distortion in sound reproduction. There are, however, very few studies on directivity control of the parametric loudspeaker. In this paper, we propose an equivalent circular Gaussian source array that approximates the directivity characteristics of the linear ultrasonic transducer array. By using this approximation, the directivity of the sound beam from the parametric loudspeaker can be predicted by the product directivity principle. New theoretical results, which are verified through measurements, are presented to show the effectiveness of the delay-and-sum beamsteering structure for the parametric loudspeaker. Unlike the conventional loudspeaker array, where the spacing between array elements must be less than half the wavelength to avoid spatial aliasing, the parametric loudspeaker can take advantage of grating lobe elimination to extend the spacing of ultrasonic transducer array to more than 1.5 wavelengths in a typical application.

  19. Estimating technical efficiency in the hospital sector with panel data: a comparison of parametric and non-parametric techniques.

    PubMed

    Siciliani, Luigi

    2006-01-01

    Policy makers are increasingly interested in developing performance indicators that measure hospital efficiency. These indicators may give the purchasers of health services an additional regulatory tool to contain health expenditure. Using panel data, this study compares different parametric (econometric) and non-parametric (linear programming) techniques for the measurement of a hospital's technical efficiency. This comparison was made using a sample of 17 Italian hospitals in the years 1996-9. Highest correlations are found in the efficiency scores between the non-parametric data envelopment analysis under the constant returns to scale assumption (DEA-CRS) and several parametric models. Correlation reduces markedly when using more flexible non-parametric specifications such as data envelopment analysis under the variable returns to scale assumption (DEA-VRS) and the free disposal hull (FDH) model. Correlation also generally reduces when moving from one output to two-output specifications. This analysis suggests that there is scope for developing performance indicators at hospital level using panel data, but it is important that extensive sensitivity analysis is carried out if purchasers wish to make use of these indicators in practice.

  20. Validated Competing Event Model for the Stage I-II Endometrial Cancer Population

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carmona, Ruben; Gulaya, Sachin; Murphy, James D.

    2014-07-15

    Purpose/Objectives(s): Early-stage endometrial cancer patients are at higher risk of noncancer mortality than of cancer mortality. Competing event models incorporating comorbidity could help identify women most likely to benefit from treatment intensification. Methods and Materials: 67,397 women with stage I-II endometrioid adenocarcinoma after total hysterectomy diagnosed from 1988 to 2009 were identified in Surveillance, Epidemiology, and End Results (SEER) and linked SEER-Medicare databases. Using demographic and clinical information, including comorbidity, we sought to develop and validate a risk score to predict the incidence of competing mortality. Results: In the validation cohort, increasing competing mortality risk score was associated with increasedmore » risk of noncancer mortality (subdistribution hazard ratio [SDHR], 1.92; 95% confidence interval [CI], 1.60-2.30) and decreased risk of endometrial cancer mortality (SDHR, 0.61; 95% CI, 0.55-0.78). Controlling for other variables, Charlson Comorbidity Index (CCI) = 1 (SDHR, 1.62; 95% CI, 1.45-1.82) and CCI >1 (SDHR, 3.31; 95% CI, 2.74-4.01) were associated with increased risk of noncancer mortality. The 10-year cumulative incidences of competing mortality within low-, medium-, and high-risk strata were 27.3% (95% CI, 25.2%-29.4%), 34.6% (95% CI, 32.5%-36.7%), and 50.3% (95% CI, 48.2%-52.6%), respectively. With increasing competing mortality risk score, we observed a significant decline in omega (ω), indicating a diminishing likelihood of benefit from treatment intensification. Conclusion: Comorbidity and other factors influence the risk of competing mortality among patients with early-stage endometrial cancer. Competing event models could improve our ability to identify patients likely to benefit from treatment intensification.« less

  1. Theory and Simulation of Gain-Guided Noncollinear Modes in Chirped Quasi-Phase-Matched Optical Parametric Amplifiers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, Martin

    Chirped quasi-phase-matched (QPM) gratings offer essentially constant gain over wide bandwidths, making them promising candidates for short-pulse optical parametric amplifiers. However, experiments have shown that high-gain non-collinear processes exist in spite of the dephasing caused by the non-uniformity of the QPM grating and compete with the desired collinear broadband gain of the amplifier. In this paper, these non-collinear gain-guided modes are investigated numerically and analytically in a model that includes longitudinal non-uniformity of the phase-matching profile, lateral localization of the pump beam and non-collinear propagation of the interacting waves.

  2. Risk

    PubMed Central

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

    2015-01-01

    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

  3. Tremor Detection Using Parametric and Non-Parametric Spectral Estimation Methods: A Comparison with Clinical Assessment

    PubMed Central

    Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H.; Maurits, Natasha M.

    2016-01-01

    In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a better insight into tremor. Typically, routine clinical assessment of accelerometry and electromyography data involves visual inspection by clinicians and occasionally computational analysis to obtain objective characteristics of tremor. However, for some tremor disorders these characteristics may be different during daily activity. This variability in presentation between the clinic and daily life makes a differential diagnosis more difficult. A long-term recording of tremor by accelerometry and/or electromyography in the home environment could help to give a better insight into the tremor disorder. However, an evaluation of such recordings using routine clinical standards would take too much time. We evaluated a range of techniques that automatically detect tremor segments in accelerometer data, as accelerometer data is more easily obtained in the home environment than electromyography data. Time can be saved if clinicians only have to evaluate the tremor characteristics of segments that have been automatically detected in longer daily activity recordings. We tested four non-parametric methods and five parametric methods on clinical accelerometer data from 14 patients with different tremor disorders. The consensus between two clinicians regarding the presence or absence of tremor on 3943 segments of accelerometer data was employed as reference. The nine methods were tested against this reference to identify their optimal parameters. Non-parametric methods generally performed better than parametric methods on our dataset when optimal parameters were used. However, one parametric method, employing the high frequency content of the tremor bandwidth under consideration

  4. Parametric robust control and system identification: Unified approach

    NASA Technical Reports Server (NTRS)

    Keel, Leehyun

    1994-01-01

    Despite significant advancement in the area of robust parametric control, the problem of synthesizing such a controller is still a wide open problem. Thus, we attempt to give a solution to this important problem. Our approach captures the parametric uncertainty as an H(sub infinity) unstructured uncertainty so that H(sub infinity) synthesis techniques are applicable. Although the techniques cannot cope with the exact parametric uncertainty, they give a reasonable guideline to model the unstructured uncertainty that contains the parametric uncertainty. An additional loop shaping technique is also introduced to relax its conservatism.

  5. Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

    PubMed

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2015-05-01

    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Registration of parametric dynamic F-18-FDG PET/CT breast images with parametric dynamic Gd-DTPA breast images

    NASA Astrophysics Data System (ADS)

    Magri, Alphonso; Krol, Andrzej; Lipson, Edward; Mandel, James; McGraw, Wendy; Lee, Wei; Tillapaugh-Fay, Gwen; Feiglin, David

    2009-02-01

    This study was undertaken to register 3D parametric breast images derived from Gd-DTPA MR and F-18-FDG PET/CT dynamic image series. Nonlinear curve fitting (Levenburg-Marquardt algorithm) based on realistic two-compartment models was performed voxel-by-voxel separately for MR (Brix) and PET (Patlak). PET dynamic series consists of 50 frames of 1-minute duration. Each consecutive PET image was nonrigidly registered to the first frame using a finite element method and fiducial skin markers. The 12 post-contrast MR images were nonrigidly registered to the precontrast frame using a free-form deformation (FFD) method. Parametric MR images were registered to parametric PET images via CT using FFD because the first PET time frame was acquired immediately after the CT image on a PET/CT scanner and is considered registered to the CT image. We conclude that nonrigid registration of PET and MR parametric images using CT data acquired during PET/CT scan and the FFD method resulted in their improved spatial coregistration. The success of this procedure was limited due to relatively large target registration error, TRE = 15.1+/-7.7 mm, as compared to spatial resolution of PET (6-7 mm), and swirling image artifacts created in MR parametric images by the FFD. Further refinement of nonrigid registration of PET and MR parametric images is necessary to enhance visualization and integration of complex diagnostic information provided by both modalities that will lead to improved diagnostic performance.

  7. Parametric and non-parametric species delimitation methods result in the recognition of two new Neotropical woody bamboo species.

    PubMed

    Ruiz-Sanchez, Eduardo

    2015-12-01

    The Neotropical woody bamboo genus Otatea is one of five genera in the subtribe Guaduinae. Of the eight described Otatea species, seven are endemic to Mexico and one is also distributed in Central and South America. Otatea acuminata has the widest geographical distribution of the eight species, and two of its recently collected populations do not match the known species morphologically. Parametric and non-parametric methods were used to delimit the species in Otatea using five chloroplast markers, one nuclear marker, and morphological characters. The parametric coalescent method and the non-parametric analysis supported the recognition of two distinct evolutionary lineages. Molecular clock estimates were used to estimate divergence times in Otatea. The results for divergence time in Otatea estimated the origin of the speciation events from the Late Miocene to Late Pleistocene. The species delimitation analyses (parametric and non-parametric) identified that the two populations of O. acuminata from Chiapas and Hidalgo are from two separate evolutionary lineages and these new species have morphological characters that separate them from O. acuminata s.s. The geological activity of the Trans-Mexican Volcanic Belt and the Isthmus of Tehuantepec may have isolated populations and limited the gene flow between Otatea species, driving speciation. Based on the results found here, I describe Otatea rzedowskiorum and Otatea victoriae as two new species, morphologically different from O. acuminata. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. A review of parametric approaches specific to aerodynamic design process

    NASA Astrophysics Data System (ADS)

    Zhang, Tian-tian; Wang, Zhen-guo; Huang, Wei; Yan, Li

    2018-04-01

    Parametric modeling of aircrafts plays a crucial role in the aerodynamic design process. Effective parametric approaches have large design space with a few variables. Parametric methods that commonly used nowadays are summarized in this paper, and their principles have been introduced briefly. Two-dimensional parametric methods include B-Spline method, Class/Shape function transformation method, Parametric Section method, Hicks-Henne method and Singular Value Decomposition method, and all of them have wide application in the design of the airfoil. This survey made a comparison among them to find out their abilities in the design of the airfoil, and the results show that the Singular Value Decomposition method has the best parametric accuracy. The development of three-dimensional parametric methods is limited, and the most popular one is the Free-form deformation method. Those methods extended from two-dimensional parametric methods have promising prospect in aircraft modeling. Since different parametric methods differ in their characteristics, real design process needs flexible choice among them to adapt to subsequent optimization procedure.

  9. Investigation of the photon statistics of parametric fluorescence in a traveling-wave parametric amplifier by means of self-homodyne tomography.

    PubMed

    Vasilyev, M; Choi, S K; Kumar, P; D'Ariano, G M

    1998-09-01

    Photon-number distributions for parametric fluorescence from a nondegenerate optical parametric amplifier are measured with a novel self-homodyne technique. These distributions exhibit the thermal-state character predicted by theory. However, a difference between the fluorescence gain and the signal gain of the parametric amplifier is observed. We attribute this difference to a change in the signal-beam profile during the traveling-wave pulsed amplification process.

  10. Competency assessment tools: An exploration of the pedagogical issues facing competency assessment for nurses in the clinical environment.

    PubMed

    Franklin, Natasha; Melville, Paula

    2015-01-01

    Competency assessment is a paradigm that is common in the healthcare environment and this being particularly true within the nursing profession. Demonstration of competence is necessary to meet the requirements of healthcare organisations and is a mandated requirement of nurses by the Nursing and Midwifery Board of Australia. Within the nursing education sector, one approach to determine competence, is through the use of competency assessment tools. Despite widespread use of competency assessment tools there remains ongoing concerns relating to the efficacy of competency assessment tools as a mean to demonstrate 'competency' amongst enrolled and registered nurses in the clinical environment. The authors of this paper ascertain that competency assessment tools run a serious risk of being nothing more than a 'quick-fix' means of assessment to demonstrate 'nursing competence' required for key performance indicators and clinical governance and that will provide evidence for accreditation standards. Based on this premise, the authors, provide an alternative approach to the use of competency assessment tools that moves away from a 'tick-box' approach to a 'patient-centred' competency model. This approach increases the reliability and validity of competency assessments, allows for the recognition of the knowledge, skills and experience of individual nurses, offers a more satisfying and rewarding approach to demonstrating 'competency' for nurses and finally, demonstrates 'real-life' competency.

  11. 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…

  12. Uncertainty importance analysis using parametric moment ratio functions.

    PubMed

    Wei, Pengfei; Lu, Zhenzhou; Song, Jingwen

    2014-02-01

    This article presents a new importance analysis framework, called parametric moment ratio function, for measuring the reduction of model output uncertainty when the distribution parameters of inputs are changed, and the emphasis is put on the mean and variance ratio functions with respect to the variances of model inputs. The proposed concepts efficiently guide the analyst to achieve a targeted reduction on the model output mean and variance by operating on the variances of model inputs. The unbiased and progressive unbiased Monte Carlo estimators are also derived for the parametric mean and variance ratio functions, respectively. Only a set of samples is needed for implementing the proposed importance analysis by the proposed estimators, thus the computational cost is free of input dimensionality. An analytical test example with highly nonlinear behavior is introduced for illustrating the engineering significance of the proposed importance analysis technique and verifying the efficiency and convergence of the derived Monte Carlo estimators. Finally, the moment ratio function is applied to a planar 10-bar structure for achieving a targeted 50% reduction of the model output variance. © 2013 Society for Risk Analysis.

  13. Refining a self-assessment of informatics competency scale using Mokken scaling analysis.

    PubMed

    Yoon, Sunmoo; Shaffer, Jonathan A; Bakken, Suzanne

    2015-01-01

    Healthcare environments are increasingly implementing health information technology (HIT) and those from various professions must be competent to use HIT in meaningful ways. In addition, HIT has been shown to enable interprofessional approaches to health care. The purpose of this article is to describe the refinement of the Self-Assessment of Nursing Informatics Competencies Scale (SANICS) using analytic techniques based upon item response theory (IRT) and discuss its relevance to interprofessional education and practice. In a sample of 604 nursing students, the 93-item version of SANICS was examined using non-parametric IRT. The iterative modeling procedure included 31 steps comprising: (1) assessing scalability, (2) assessing monotonicity, (3) assessing invariant item ordering, and (4) expert input. SANICS was reduced to an 18-item hierarchical scale with excellent reliability. Fundamental skills for team functioning and shared decision making among team members (e.g. "using monitoring systems appropriately," "describing general systems to support clinical care") had the highest level of difficulty, and "demonstrating basic technology skills" had the lowest difficulty level. Most items reflect informatics competencies relevant to all health professionals. Further, the approaches can be applied to construct a new hierarchical scale or refine an existing scale related to informatics attitudes or competencies for various health professions.

  14. A novel SURE-based criterion for parametric PSF estimation.

    PubMed

    Xue, Feng; Blu, Thierry

    2015-02-01

    We propose an unbiased estimate of a filtered version of the mean squared error--the blur-SURE (Stein's unbiased risk estimate)--as a novel criterion for estimating an unknown point spread function (PSF) from the degraded image only. The PSF is obtained by minimizing this new objective functional over a family of Wiener processings. Based on this estimated blur kernel, we then perform nonblind deconvolution using our recently developed algorithm. The SURE-based framework is exemplified with a number of parametric PSF, involving a scaling factor that controls the blur size. A typical example of such parametrization is the Gaussian kernel. The experimental results demonstrate that minimizing the blur-SURE yields highly accurate estimates of the PSF parameters, which also result in a restoration quality that is very similar to the one obtained with the exact PSF, when plugged into our recent multi-Wiener SURE-LET deconvolution algorithm. The highly competitive results obtained outline the great potential of developing more powerful blind deconvolution algorithms based on SURE-like estimates.

  15. Competent Children at Risk: Their Parents and Families. 2. Markers of Competent Children.

    ERIC Educational Resources Information Center

    Kokes, Ronald F.; And Others

    Hypotheses presented in an initial report of this study were tested and, in general, all were supported. Maternal diagnosis, chronicity, and age of onset with regard to the child and to parent/child interaction were significantly associated with child competence. However, effects of these factors were not consistent across age of child or child…

  16. On the importance of accounting for competing risks in pediatric cancer trials designed to delay or avoid radiotherapy: I. Basic concepts and first analyses.

    PubMed

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

    2010-04-01

    In trials designed to delay or avoid irradiation among children with malignant brain tumor, although irradiation after disease progression is an important event, patients who have disease progression may decline radiotherapy (RT), or those without disease progression may opt for elective RT. To accurately describe the cumulative need for RT in such instances, it is crucial to account for these distinct events and to evaluate how each contributes to the delay or advancement of irradiation via a competing risks analysis. We describe the summary of competing events in such trials using competing risks methods based on cumulative incidence functions and Gray's test. The results obtained are contrasted with standard survival methods based on Kaplan-Meier curves, cause-specific hazard functions and log-rank test. The Kaplan-Meier method overestimates all event-specific rates. The cause-specific hazard analysis showed reduction in hazards for all events (A: RT after progression; B: no RT after progression; C: elective RT) among children with ependymoma. For event A, a higher cumulative incidence was reported for ependymoma. Although Gray's test failed to detect any difference (p = 0.331) between histologic subtypes, the log-rank test suggested marginal evidence (p = 0.057). Similarly, for event C, the log-rank test found stronger evidence of reduction in hazard among those with ependymoma (p = 0.005) as compared with Gray's test (p = 0.086). To evaluate treatment differences, failing to account for competing risks using appropriate methodology may lead to incorrect interpretations.

  17. 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.

  18. Proposed Core Competencies and Empirical Validation Procedure in Competency Modeling: Confirmation and Classification.

    PubMed

    Baczyńska, Anna K; Rowiński, Tomasz; Cybis, Natalia

    2016-01-01

    Competency models provide insight into key skills which are common to many positions in an organization. Moreover, there is a range of competencies that is used by many companies. Researchers have developed core competency terminology to underline their cross-organizational value. The article presents a theoretical model of core competencies consisting of two main higher-order competencies called performance and entrepreneurship. Each of them consists of three elements: the performance competency includes cooperation, organization of work and goal orientation, while entrepreneurship includes innovativeness, calculated risk-taking and pro-activeness. However, there is lack of empirical validation of competency concepts in organizations and this would seem crucial for obtaining reliable results from organizational research. We propose a two-step empirical validation procedure: (1) confirmation factor analysis, and (2) classification of employees. The sample consisted of 636 respondents (M = 44.5; SD = 15.1). Participants were administered a questionnaire developed for the study purpose. The reliability, measured by Cronbach's alpha, ranged from 0.60 to 0.83 for six scales. Next, we tested the model using a confirmatory factor analysis. The two separate, single models of performance and entrepreneurial orientations fit quite well to the data, while a complex model based on the two single concepts needs further research. In the classification of employees based on the two higher order competencies we obtained four main groups of employees. Their profiles relate to those found in the literature, including so-called niche finders and top performers. Some proposal for organizations is discussed.

  19. Proposed Core Competencies and Empirical Validation Procedure in Competency Modeling: Confirmation and Classification

    PubMed Central

    Baczyńska, Anna K.; Rowiński, Tomasz; Cybis, Natalia

    2016-01-01

    Competency models provide insight into key skills which are common to many positions in an organization. Moreover, there is a range of competencies that is used by many companies. Researchers have developed core competency terminology to underline their cross-organizational value. The article presents a theoretical model of core competencies consisting of two main higher-order competencies called performance and entrepreneurship. Each of them consists of three elements: the performance competency includes cooperation, organization of work and goal orientation, while entrepreneurship includes innovativeness, calculated risk-taking and pro-activeness. However, there is lack of empirical validation of competency concepts in organizations and this would seem crucial for obtaining reliable results from organizational research. We propose a two-step empirical validation procedure: (1) confirmation factor analysis, and (2) classification of employees. The sample consisted of 636 respondents (M = 44.5; SD = 15.1). Participants were administered a questionnaire developed for the study purpose. The reliability, measured by Cronbach’s alpha, ranged from 0.60 to 0.83 for six scales. Next, we tested the model using a confirmatory factor analysis. The two separate, single models of performance and entrepreneurial orientations fit quite well to the data, while a complex model based on the two single concepts needs further research. In the classification of employees based on the two higher order competencies we obtained four main groups of employees. Their profiles relate to those found in the literature, including so-called niche finders and top performers. Some proposal for organizations is discussed. PMID:27014111

  20. Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

    NASA Astrophysics Data System (ADS)

    Pentaris, Fragkiskos P.; Fouskitakis, George N.

    2014-05-01

    The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5

  1. Parametrically disciplined operation of a vibratory gyroscope

    NASA Technical Reports Server (NTRS)

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

  2. Parametric FEM for geometric biomembranes

    NASA Astrophysics Data System (ADS)

    Bonito, Andrea; Nochetto, Ricardo H.; Sebastian Pauletti, M.

    2010-05-01

    We consider geometric biomembranes governed by an L2-gradient flow for bending energy subject to area and volume constraints (Helfrich model). We give a concise derivation of a novel vector formulation, based on shape differential calculus, and corresponding discretization via parametric FEM using quadratic isoparametric elements and a semi-implicit Euler method. We document the performance of the new parametric FEM with a number of simulations leading to dumbbell, red blood cell and toroidal equilibrium shapes while exhibiting large deformations.

  3. Ku band low noise parametric amplifier

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A low noise, K sub u-band, parametric amplifier (paramp) was developed. The unit is a spacecraft-qualifiable, prototype, parametric amplifier for eventual application in the shuttle orbiter. The amplifier was required to have a noise temperature of less than 150 K. A noise temperature of less than 120 K at a gain level of 17 db was achieved. A 3-db bandwidth in excess of 350 MHz was attained, while deviation from phase linearity of about + or - 1 degree over 50 MHz was achieved. The paramp operates within specification over an ambient temperature range of -5 C to +50 C. The performance requirements and the operation of the K sub u-band parametric amplifier system are described. The final test results are also given.

  4. Parametric analysis of ATM solar array.

    NASA Technical Reports Server (NTRS)

    Singh, B. K.; Adkisson, W. B.

    1973-01-01

    The paper discusses the methods used for the calculation of ATM solar array performance characteristics and provides the parametric analysis of solar panels used in SKYLAB. To predict the solar array performance under conditions other than test conditions, a mathematical model has been developed. Four computer programs have been used to convert the solar simulator test data to the parametric curves. The first performs module summations, the second determines average solar cell characteristics which will cause a mathematical model to generate a curve matching the test data, the third is a polynomial fit program which determines the polynomial equations for the solar cell characteristics versus temperature, and the fourth program uses the polynomial coefficients generated by the polynomial curve fit program to generate the parametric data.

  5. 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

  6. Housing price prediction: parametric versus semi-parametric spatial hedonic models

    NASA Astrophysics Data System (ADS)

    Montero, José-María; Mínguez, Román; Fernández-Avilés, Gema

    2018-01-01

    House price prediction is a hot topic in the economic literature. House price prediction has traditionally been approached using a-spatial linear (or intrinsically linear) hedonic models. It has been shown, however, that spatial effects are inherent in house pricing. This article considers parametric and semi-parametric spatial hedonic model variants that account for spatial autocorrelation, spatial heterogeneity and (smooth and nonparametrically specified) nonlinearities using penalized splines methodology. The models are represented as a mixed model that allow for the estimation of the smoothing parameters along with the other parameters of the model. To assess the out-of-sample performance of the models, the paper uses a database containing the price and characteristics of 10,512 homes in Madrid, Spain (Q1 2010). The results obtained suggest that the nonlinear models accounting for spatial heterogeneity and flexible nonlinear relationships between some of the individual or areal characteristics of the houses and their prices are the best strategies for house price prediction.

  7. 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…

  8. Comparison of thawing and freezing dark energy parametrizations

    NASA Astrophysics Data System (ADS)

    Pantazis, G.; Nesseris, S.; Perivolaropoulos, L.

    2016-05-01

    Dark energy equation of state w (z ) parametrizations with two parameters and given monotonicity are generically either convex or concave functions. This makes them suitable for fitting either freezing or thawing quintessence models but not both simultaneously. Fitting a data set based on a freezing model with an unsuitable (concave when increasing) w (z ) parametrization [like Chevallier-Polarski-Linder (CPL)] can lead to significant misleading features like crossing of the phantom divide line, incorrect w (z =0 ), incorrect slope, etc., that are not present in the underlying cosmological model. To demonstrate this fact we generate scattered cosmological data at both the level of w (z ) and the luminosity distance DL(z ) based on either thawing or freezing quintessence models and fit them using parametrizations of convex and of concave type. We then compare statistically significant features of the best fit w (z ) with actual features of the underlying model. We thus verify that the use of unsuitable parametrizations can lead to misleading conclusions. In order to avoid these problems it is important to either use both convex and concave parametrizations and select the one with the best χ2 or use principal component analysis thus splitting the redshift range into independent bins. In the latter case, however, significant information about the slope of w (z ) at high redshifts is lost. Finally, we propose a new family of parametrizations w (z )=w0+wa(z/1 +z )n which generalizes the CPL and interpolates between thawing and freezing parametrizations as the parameter n increases to values larger than 1.

  9. Long-Term Disease-Free Survival of Non-Metastatic Breast Cancer Patients in Iran: A Survival Model with Competing Risks Taking Cure Fraction and Frailty into Account

    PubMed

    Ghavami, Vahid; Mahmoudi, Mahmood; Rahimi Foroushani, Abbas; Baghishani, Hossein; Homaei Shandiz, Fatemeh; Yaseri, Mehdi

    2017-10-26

    Introduction: Survival modeling is a very important tool to detect risk factors and provide a basis for health care planning. However, cancer data may have properties leading to distorted results with routine methods. Therefore, this study aimed to cover specific factors (competing risk, cure fraction and heterogeneity) with a real dataset of Iranian breast cancer patients using a competing risk-cure-frailty model. Materials and methods: For this historical cohort study, information for 550 Iranian breast cancer patients who underwent surgery for tumor removal from 2001 to 2007 and were followed up to March 2017, was analyzed using R 3.2 software. Results: In contrast to T-stage and N-stage, hormone receptor status did not have any significant effect on the cure fraction (long-term disease-free survival). However, T-stage, N-stage and hormone receptor status all had a significant effect on short-term disease-free survival so that the hazard of loco-regional relapse or distant metastasis in cases positive for a hormone receptor was only 0.3 times that for their negative hormone receptor counterparts. The likelihood of locoregional relapse in the first quartile of follow up was nearly twice that of other quartiles. The least cumulative incidence of time to locoregional relapse was for cases with a positive hormone receptor, low N stage and low T stage. The effect of frailty term was significant in this study and a model with frailty appeared more appropriate than a model without, based on the Akaike information criterion (AIC); values for the frailty model and one without the frailty parameter were 1370.39 and 1381.46, respectively. Conclusions: The data from this study indicate ae necessity to consider competing risk, cure fraction and heterogeneity in survival modeling. The competing risk-cure-frailty model can cover complex situations with survival data. Creative Commons Attribution License

  10. Parametric pendulum based wave energy converter

    NASA Astrophysics Data System (ADS)

    Yurchenko, Daniil; Alevras, Panagiotis

    2018-01-01

    The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

  11. SPM analysis of parametric (R)-[11C]PK11195 binding images: plasma input versus reference tissue parametric methods.

    PubMed

    Schuitemaker, Alie; van Berckel, Bart N M; Kropholler, Marc A; Veltman, Dick J; Scheltens, Philip; Jonker, Cees; Lammertsma, Adriaan A; Boellaard, Ronald

    2007-05-01

    (R)-[11C]PK11195 has been used for quantifying cerebral microglial activation in vivo. In previous studies, both plasma input and reference tissue methods have been used, usually in combination with a region of interest (ROI) approach. Definition of ROIs, however, can be labourious and prone to interobserver variation. In addition, results are only obtained for predefined areas and (unexpected) signals in undefined areas may be missed. On the other hand, standard pharmacokinetic models are too sensitive to noise to calculate (R)-[11C]PK11195 binding on a voxel-by-voxel basis. Linearised versions of both plasma input and reference tissue models have been described, and these are more suitable for parametric imaging. The purpose of this study was to compare the performance of these plasma input and reference tissue parametric methods on the outcome of statistical parametric mapping (SPM) analysis of (R)-[11C]PK11195 binding. Dynamic (R)-[11C]PK11195 PET scans with arterial blood sampling were performed in 7 younger and 11 elderly healthy subjects. Parametric images of volume of distribution (Vd) and binding potential (BP) were generated using linearised versions of plasma input (Logan) and reference tissue (Reference Parametric Mapping) models. Images were compared at the group level using SPM with a two-sample t-test per voxel, both with and without proportional scaling. Parametric BP images without scaling provided the most sensitive framework for determining differences in (R)-[11C]PK11195 binding between younger and elderly subjects. Vd images could only demonstrate differences in (R)-[11C]PK11195 binding when analysed with proportional scaling due to intersubject variation in K1/k2 (blood-brain barrier transport and non-specific binding).

  12. Characterization of a multimode coplanar waveguide parametric amplifier

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Simoen, M., E-mail: simoen@chalmers.se; Krantz, P.; Bylander, Jonas

    2015-10-21

    We characterize a Josephson parametric amplifier based on a flux-tunable quarter-wavelength resonator. The fundamental resonance frequency is ∼1 GHz, but we use higher modes of the resonator for our measurements. An on-chip tuning line allows for magnetic flux pumping of the amplifier. We investigate and compare degenerate parametric amplification, involving a single mode, and nondegenerate parametric amplification, using a pair of modes. We show that we reach quantum-limited noise performance in both cases.

  13. Advantage of the modified Lunn-McNeil technique over Kalbfleisch-Prentice technique in competing risks

    NASA Astrophysics Data System (ADS)

    Lukman, Iing; Ibrahim, Noor A.; Daud, Isa B.; Maarof, Fauziah; Hassan, Mohd N.

    2002-03-01

    Survival analysis algorithm is often applied in the data mining process. Cox regression is one of the survival analysis tools that has been used in many areas, and it can be used to analyze the failure times of aircraft crashed. Another survival analysis tool is the competing risks where we have more than one cause of failure acting simultaneously. Lunn-McNeil analyzed the competing risks in the survival model using Cox regression with censored data. The modified Lunn-McNeil technique is a simplify of the Lunn-McNeil technique. The Kalbfleisch-Prentice technique is involving fitting models separately from each type of failure, treating other failure types as censored. To compare the two techniques, (the modified Lunn-McNeil and Kalbfleisch-Prentice) a simulation study was performed. Samples with various sizes and censoring percentages were generated and fitted using both techniques. The study was conducted by comparing the inference of models, using Root Mean Square Error (RMSE), the power tests, and the Schoenfeld residual analysis. The power tests in this study were likelihood ratio test, Rao-score test, and Wald statistics. The Schoenfeld residual analysis was conducted to check the proportionality of the model through its covariates. The estimated parameters were computed for the cause-specific hazard situation. Results showed that the modified Lunn-McNeil technique was better than the Kalbfleisch-Prentice technique based on the RMSE measurement and Schoenfeld residual analysis. However, the Kalbfleisch-Prentice technique was better than the modified Lunn-McNeil technique based on power tests measurement.

  14. Risk in Science Instruction. The Realist and Constructivist Paradigms of Risk

    NASA Astrophysics Data System (ADS)

    Hansen, Julia; Hammann, Marcus

    2017-11-01

    Risk is always present in people's lives: diseases, new technologies, socio-scientific issues (SSIs) such as climate change, and advances in medicine—to name just a few examples—all carry risks. To be able to navigate risks in everyday life, as well as to participate in social debate on risk-related issues, students need to develop risk competence. Science education can be a powerful tool in supporting students' risk competence, which is an important component of scientific literacy. As there are different definitions of risk within the scientific community, the aims of this article are (1) to review the literature on two major theoretical frameworks for conceptualising risk, the realist, and the constructivist paradigms of risk and (2) to connect both in order to suggest a working definition of what can be understood as risk competence in science instruction.

  15. A Cartesian parametrization for the numerical analysis of material instability

    DOE PAGES

    Mota, Alejandro; Chen, Qiushi; Foulk, III, James W.; ...

    2016-02-25

    We examine four parametrizations of the unit sphere in the context of material stability analysis by means of the singularity of the acoustic tensor. We then propose a Cartesian parametrization for vectors that lie a cube of side length two and use these vectors in lieu of unit normals to test for the loss of the ellipticity condition. This parametrization is then used to construct a tensor akin to the acoustic tensor. It is shown that both of these tensors become singular at the same time and in the same planes in the presence of a material instability. Furthermore, themore » performance of the Cartesian parametrization is compared against the other parametrizations, with the results of these comparisons showing that in general, the Cartesian parametrization is more robust and more numerically efficient than the others.« less

  16. A Cartesian parametrization for the numerical analysis of material instability

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mota, Alejandro; Chen, Qiushi; Foulk, III, James W.

    We examine four parametrizations of the unit sphere in the context of material stability analysis by means of the singularity of the acoustic tensor. We then propose a Cartesian parametrization for vectors that lie a cube of side length two and use these vectors in lieu of unit normals to test for the loss of the ellipticity condition. This parametrization is then used to construct a tensor akin to the acoustic tensor. It is shown that both of these tensors become singular at the same time and in the same planes in the presence of a material instability. Furthermore, themore » performance of the Cartesian parametrization is compared against the other parametrizations, with the results of these comparisons showing that in general, the Cartesian parametrization is more robust and more numerically efficient than the others.« less

  17. Parametric Methods for Dynamic 11C-Phenytoin PET Studies.

    PubMed

    Mansor, Syahir; Yaqub, Maqsood; Boellaard, Ronald; Froklage, Femke E; de Vries, Anke; Bakker, Esther D M; Voskuyl, Rob A; Eriksson, Jonas; Schwarte, Lothar A; Verbeek, Joost; Windhorst, Albert D; Lammertsma, Adriaan A

    2017-03-01

    In this study, the performance of various methods for generating quantitative parametric images of dynamic 11 C-phenytoin PET studies was evaluated. Methods: Double-baseline 60-min dynamic 11 C-phenytoin PET studies, including online arterial sampling, were acquired for 6 healthy subjects. Parametric images were generated using Logan plot analysis, a basis function method, and spectral analysis. Parametric distribution volume (V T ) and influx rate ( K 1 ) were compared with those obtained from nonlinear regression analysis of time-activity curves. In addition, global and regional test-retest (TRT) variability was determined for parametric K 1 and V T values. Results: Biases in V T observed with all parametric methods were less than 5%. For K 1 , spectral analysis showed a negative bias of 16%. The mean TRT variabilities of V T and K 1 were less than 10% for all methods. Shortening the scan duration to 45 min provided similar V T and K 1 with comparable TRT performance compared with 60-min data. Conclusion: Among the various parametric methods tested, the basis function method provided parametric V T and K 1 values with the least bias compared with nonlinear regression data and showed TRT variabilities lower than 5%, also for smaller volume-of-interest sizes (i.e., higher noise levels) and shorter scan duration. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  18. 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.

  19. 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.

  20. Extended parametric representation of compressor fans and turbines. Volume 2: Part user's manual (parametric turbine)

    NASA Technical Reports Server (NTRS)

    Coverse, G. L.

    1984-01-01

    A turbine modeling technique has been developed which will enable the user to obtain consistent and rapid off-design performance from design point input. This technique is applicable to both axial and radial flow turbine with flow sizes ranging from about one pound per second to several hundred pounds per second. The axial flow turbines may or may not include variable geometry in the first stage nozzle. A user-specified option will also permit the calculation of design point cooling flow levels and corresponding changes in efficiency for the axial flow turbines. The modeling technique has been incorporated into a time-sharing program in order to facilitate its use. Because this report contains a description of the input output data, values of typical inputs, and example cases, it is suitable as a user's manual. This report is the second of a three volume set. The titles of the three volumes are as follows: (1) Volume 1 CMGEN USER's Manual (Parametric Compressor Generator); (2) Volume 2 PART USER's Manual (Parametric Turbine); (3) Volume 3 MODFAN USER's Manual (Parametric Modulation Flow Fan).

  1. 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…

  2. Cumulative Risk, Negative Emotionality, and Emotion Regulation as Predictors of Social Competence in Transition to School: A Mediated Moderation Model

    ERIC Educational Resources Information Center

    Chang, Hyein; Shelleby, Elizabeth C.; Cheong, JeeWon; Shaw, Daniel S.

    2012-01-01

    The goals of this study were to examine the additive and interactive effects of cumulative risk and child negative emotionality on children's social competence in the transition from preschool to school and to test whether these associations were mediated by child emotion regulation within a sample of 310 low-income, ethnically diverse boys.…

  3. Androgen Deprivation Therapy Use in the Setting of High-dose Radiation Therapy and the Risk of Prostate Cancer–Specific Mortality Stratified by the Extent of Competing Mortality

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rose, Brent S., E-mail: brose44@gmail.com; Chen, Ming-Hui; Wu, Jing

    Purpose: The addition of androgen deprivation therapy (ADT) to radiation therapy (RT) is the standard of care for men with intermediate- and high-risk prostate cancer (PC). However, whether competing mortality (CM) affects the ability of ADT to improve, survival remains unanswered. Methods and Materials: We calculated a CM risk score using a Fine-Gray semiparametric model that included age and cardiometabolic comorbidities from a cohort of 17,669 men treated with high-dose RT with or without supplemental ADT for nonmetastatic PC. Fine and Gray competing risk regression analysis was used to assess whether ADT reduced the risk of PC-specific mortality for menmore » with a low versus a high risk of CM among the 4550 patients within the intermediate- and high-risk cohort after adjustment for established PC prognostic factors, year of treatment, site, and ADT propensity score. Results: After a median follow-up of 8.4 years, 1065 men had died, 89 (8.36%) of PC. Among the men with a low CM score, ADT use was associated with a significant reduction in the risk of PC-specific mortality (adjusted hazard ratio 0.35, 95% confidence interval 0.14-0.87, P=.02) but was not for men with high CM (adjusted hazard ratio 1.33, 95% confidence interval 0.77-2.30, P=.30). Conclusions: Adding ADT to high-dose RT appears to be associated with decreased PC-specific mortality risk in men with a low but not a high CM score. These data should serve to heighten awareness about the importance of considering competing risks when determining whether to add ADT to RT for older men with intermediate- or high-risk PC.« less

  4. Marginally specified priors for non-parametric Bayesian estimation

    PubMed Central

    Kessler, David C.; Hoff, Peter D.; Dunson, David B.

    2014-01-01

    Summary Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables. PMID:25663813

  5. Access to Heart Transplantation: A Proper Analysis of the Competing Risks of Death and Transplantation Is Required to Optimize Graft Allocation.

    PubMed

    Cantrelle, Christelle; Legeai, Camille; Latouche, Aurélien; Tuppin, Philippe; Jasseron, Carine; Sebbag, Laurent; Bastien, Olivier; Dorent, Richard

    2017-08-01

    Heart allocation systems are usually urgency-based, offering grafts to candidates at high risk of waitlist mortality. In the context of a revision of the heart allocation rules, we determined observed predictors of 1-year waitlist mortality in France, considering the competing risk of transplantation, to determine which candidate subgroups are favored or disadvantaged by the current allocation system. Patients registered on the French heart waitlist between 2010 and 2013 were included. Cox cause-specific hazards and Fine and Gray subdistribution hazards were used to determine candidate characteristics associated with waitlist mortality and access to transplantation. Of the 2053 candidates, 7 variables were associated with 1-year waitlist mortality by the Fine and Gray method including 4 candidate characteristics related to heart failure severity (hospitalization at listing, serum natriuretic peptide level, systolic pulmonary artery pressure, and glomerular filtration rate) and 3 characteristics not associated with heart failure severity but with lower access to transplantation (blood type, age, and body mass index). Observed waitlist mortality for candidates on mechanical circulatory support was like that of others. The heart allocation system strongly modifies the risk of pretransplant mortality related to heart failure severity. An in-depth competing risk analysis is therefore a more appropriate method to evaluate graft allocation systems. This knowledge should help to prioritize candidates in the context of a limited donor pool.

  6. Evaluating the Quality of Competency Assessment in Pharmacy: A Framework for Workplace Learning.

    PubMed

    Shah, Shailly; McLaughlin, Jacqueline E; Eckel, Stephen F; Mangun, Jesica; Hawes, Emily

    2016-01-19

    Demonstration of achieved competencies is critical in the pharmacy workplace. The purpose of this study was to evaluate the quality of the competency assessment program for pharmacy residents at an academic medical center. The competency assessment program (CAP) survey is a validated, 48-item instrument that evaluates the quality of an assessment program based on 12 criteria, each measured by four questions on a scale of 0 to 100. The CAP was completed by residents ( n = 23) and preceptors ( n = 28) from the pharmacy residency program between 2010 and 2013. Results were analyzed using descriptive statistics, Cronbach's alpha, and non-parametric tests. Educational Consequences was the only quality criteria falling below the standard for "good quality." Participants that completed residency training elsewhere rated the Comparability (0.04) and Meaningfulness (0.01) of the assessment program higher than those that completed residency at the academic medical center. There were no significant differences between resident and preceptor scores. Overall, the quality of the assessment program was rated highly by residents and preceptors. The process described here provides a useful framework for understanding the quality of workplace learning assessments in pharmacy practice.

  7. Alternative evaluation metrics for risk adjustment methods.

    PubMed

    Park, Sungchul; Basu, Anirban

    2018-06-01

    Risk adjustment is instituted to counter risk selection by accurately equating payments with expected expenditures. Traditional risk-adjustment methods are designed to estimate accurate payments at the group level. However, this generates residual risks at the individual level, especially for high-expenditure individuals, thereby inducing health plans to avoid those with high residual risks. To identify an optimal risk-adjustment method, we perform a comprehensive comparison of prediction accuracies at the group level, at the tail distributions, and at the individual level across 19 estimators: 9 parametric regression, 7 machine learning, and 3 distributional estimators. Using the 2013-2014 MarketScan database, we find that no one estimator performs best in all prediction accuracies. Generally, machine learning and distribution-based estimators achieve higher group-level prediction accuracy than parametric regression estimators. However, parametric regression estimators show higher tail distribution prediction accuracy and individual-level prediction accuracy, especially at the tails of the distribution. This suggests that there is a trade-off in selecting an appropriate risk-adjustment method between estimating accurate payments at the group level and lower residual risks at the individual level. Our results indicate that an optimal method cannot be determined solely on the basis of statistical metrics but rather needs to account for simulating plans' risk selective behaviors. Copyright © 2018 John Wiley & Sons, Ltd.

  8. 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

  9. Cumulative incidence rate of medical consultation for fecundity problems--analysis of a prevalent cohort using competing risks.

    PubMed

    Duron, S; Slama, R; Ducot, B; Bohet, A; Sørensen, D N; Keiding, N; Moreau, C; Bouyer, J

    2013-10-01

    What is the incidence of medical consultation for fecundity problems in the French population, taking into account pregnancy occurrence and resumption of contraceptive use?. Considering the occurrence of a pregnancy and resumption of use of contraception as competing risks, the cumulative incidence rate of medical consultation for fecundity problems was 9.0% [95% confidence interval (CI): 6.5%; 11.9%] after 12 months of unprotected intercourse and 12.2% [95% CI: 9.6%; 15.3%] after 24 months. Estimates of the prevalence of medical consultation due to involuntary infertility among couples who have sought a pregnancy for more than 12 months range from 25 to 50%. Most of the studies however are limited by retrospective data collection, without considering the duration of time since the beginning of the period of unprotected intercourse (PUI) and without considering medical consultation for fecundity problems as a competing risk. This study is based on the Observatory of Fecundity in France survey, a population-based probability survey designed to estimate the frequency of involuntary infertility on a nationwide basis and to explore the associations with environmental factors. Women answered two telephone questionnaires, the first at the time of enrolment in 2007, the second at follow-up 1 year later. The current analysis was performed among a subsample of 6577 women recruited before or during a PUI and followed-up for 1 year. The study sample comprised 940 women aged 18-44 years who had a PUI between the time of enrolment and the 1-year follow-up, and who had not consulted a physician for fecundity problems for the current PUI prior to enrolment. Women reported all the medical consultations they had because of difficulties becoming pregnant during the current PUI. The date of each consultation was carefully assessed. In France, women can consult a gynaecologist directly without referral by their general practitioner. The occurrence of a pregnancy and resumption of

  10. A parametric ribcage geometry model accounting for variations among the adult population.

    PubMed

    Wang, Yulong; Cao, Libo; Bai, Zhonghao; Reed, Matthew P; Rupp, Jonathan D; Hoff, Carrie N; Hu, Jingwen

    2016-09-06

    The objective of this study is to develop a parametric ribcage model that can account for morphological variations among the adult population. Ribcage geometries, including 12 pair of ribs, sternum, and thoracic spine, were collected from CT scans of 101 adult subjects through image segmentation, landmark identification (1016 for each subject), symmetry adjustment, and template mesh mapping (26,180 elements for each subject). Generalized procrustes analysis (GPA), principal component analysis (PCA), and regression analysis were used to develop a parametric ribcage model, which can predict nodal locations of the template mesh according to age, sex, height, and body mass index (BMI). Two regression models, a quadratic model for estimating the ribcage size and a linear model for estimating the ribcage shape, were developed. The results showed that the ribcage size was dominated by the height (p=0.000) and age-sex-interaction (p=0.007) and the ribcage shape was significantly affected by the age (p=0.0005), sex (p=0.0002), height (p=0.0064) and BMI (p=0.0000). Along with proper assignment of cortical bone thickness, material properties and failure properties, this parametric ribcage model can directly serve as the mesh of finite element ribcage models for quantifying effects of human characteristics on thoracic injury risks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Injection-seeded optical parametric oscillator and system

    DOEpatents

    Lucht, Robert P.; Kulatilaka, Waruna D.; Anderson, Thomas N.; Bougher, Thomas L.

    2007-10-09

    Optical parametric oscillators (OPO) and systems are provided. The OPO has a non-linear optical material located between two optical elements where the product of the reflection coefficients of the optical elements are higher at the output wavelength than at either the pump or idler wavelength. The OPO output may be amplified using an additional optical parametric amplifier (OPA) stage.

  12. Estimating Counterfactual Risk Under Hypothetical Interventions in the Presence of Competing Events: Crystalline Silica Exposure and Mortality From two Causes of Death.

    PubMed

    Neophytou, Andreas M; Picciotto, Sally; Brown, Daniel M; Gallagher, Lisa E; Checkoway, Harvey; Eisen, Ellen A; Costello, Sadie

    2018-04-03

    Exposure to silica has been linked to excess risk of lung cancer and non-malignant respiratory disease mortality. In this study we estimated risk for both these outcomes in relation to occupational silica exposure as well as the reduction in risk that would result from hypothetical interventions on exposure in a cohort of exposed workers. Analyses were carried out in an all-male study population consisting of 2342 California diatomaceous earth workers regularly exposed to crystalline silica, followed between 1942 and 2011. We estimated subdistribution risk for each event under the natural course and interventions of interest using the parametric g-formula to adjust for healthy worker survivor bias. The risk ratio for lung cancer mortality comparing an intervention in which a theoretical maximum exposure limit was set at 0.05 mg/m3 (the current U.S. regulatory limit) to the observed exposure concentrations was 0.86 (95% confidence interval: 0.63, 1.22). The corresponding risk ratio for non-malignant respiratory disease mortality was 0.69 (95% confidence interval: 0.52, 0.93). Our findings suggest that risks from both outcomes would have been considerably lower if historical silica exposures in this cohort had not exceeded current regulatory limits.

  13. Risk of Cause-Specific Death in Individuals With Diabetes: A Competing Risks Analysis.

    PubMed

    Baena-Díez, Jose Miguel; Peñafiel, Judit; Subirana, Isaac; Ramos, Rafel; Elosua, Roberto; Marín-Ibañez, Alejandro; Guembe, María Jesús; Rigo, Fernando; Tormo-Díaz, María José; Moreno-Iribas, Conchi; Cabré, Joan Josep; Segura, Antonio; García-Lareo, Manel; Gómez de la Cámara, Agustín; Lapetra, José; Quesada, Miquel; Marrugat, Jaume; Medrano, Maria José; Berjón, Jesús; Frontera, Guiem; Gavrila, Diana; Barricarte, Aurelio; Basora, Josep; García, Jose María; Pavone, Natalia C; Lora-Pablos, David; Mayoral, Eduardo; Franch, Josep; Mata, Manel; Castell, Conxa; Frances, Albert; Grau, María

    2016-11-01

    Diabetes is a common cause of shortened life expectancy. We aimed to assess the association between diabetes and cause-specific death. We used the pooled analysis of individual data from 12 Spanish population cohorts with 10-year follow-up. Participants had no previous history of cardiovascular diseases and were 35-79 years old. Diabetes status was self-reported or defined as glycemia >125 mg/dL at baseline. Vital status and causes of death were ascertained by medical records review and linkage with the official death registry. The hazard ratios and cumulative mortality function were assessed with two approaches, with and without competing risks: proportional subdistribution hazard (PSH) and cause-specific hazard (CSH), respectively. Multivariate analyses were fitted for cardiovascular, cancer, and noncardiovascular noncancer deaths. We included 55,292 individuals (15.6% with diabetes and overall mortality of 9.1%). The adjusted hazard ratios showed that diabetes increased mortality risk: 1) cardiovascular death, CSH = 2.03 (95% CI 1.63-2.52) and PSH = 1.99 (1.60-2.49) in men; and CSH = 2.28 (1.75-2.97) and PSH = 2.23 (1.70-2.91) in women; 2) cancer death, CSH = 1.37 (1.13-1.67) and PSH = 1.35 (1.10-1.65) in men; and CSH = 1.68 (1.29-2.20) and PSH = 1.66 (1.25-2.19) in women; and 3) noncardiovascular noncancer death, CSH = 1.53 (1.23-1.91) and PSH = 1.50 (1.20-1.89) in men; and CSH = 1.89 (1.43-2.48) and PSH = 1.84 (1.39-2.45) in women. In all instances, the cumulative mortality function was significantly higher in individuals with diabetes. Diabetes is associated with premature death from cardiovascular disease, cancer, and noncardiovascular noncancer causes. The use of CSH and PSH provides a comprehensive view of mortality dynamics in a population with diabetes. © 2016 by the American Diabetes Association.

  14. Parametric instability induced by X-mode wave heating at EISCAT

    NASA Astrophysics Data System (ADS)

    Wang, Xiang; Zhou, Chen; Liu, Moran; Honary, Farideh; Ni, Binbin; Zhao, Zhengyu

    2016-10-01

    In this paper, we present results of parametric instability induced by X-mode wave heating observed by EISCAT (European Incoherent Scatter Scientific Association) radar at Tromsø, Norway. Three typical X-mode ionospheric heating experiments on 22 October 2013, 19 October 2012, and 21 February 2013 are investigated in details. Both parametric decay instability (PDI) and oscillating two-stream instability are observed during the X-mode heating period. We suggest that the full dispersion relationship of the Langmuir wave can be employed to analyze the X-mode parametric instability excitation. A modified kinetic electron distribution is proposed and analyzed, which is able to satisfy the matching condition of parametric instability excitation. Parallel electric field component of X-mode heating wave can also exceed the parametric instability excitation threshold under certain conditions.

  15. Modeling the directivity of parametric loudspeaker

    NASA Astrophysics Data System (ADS)

    Shi, Chuang; Gan, Woon-Seng

    2012-09-01

    The emerging applications of the parametric loudspeaker, such as 3D audio, demands accurate directivity control at the audible frequency (i.e. the difference frequency). Though the delay-and-sum beamforming has been proven adequate to adjust the steering angles of the parametric loudspeaker, accurate prediction of the mainlobe and sidelobes remains a challenging problem. It is mainly because of the approximations that are used to derive the directivity of the difference frequency from the directivity of the primary frequency, and the mismatches between the theoretical directivity and the measured directivity caused by system errors incurred at different stages of the implementation. In this paper, we propose a directivity model of the parametric loudspeaker. The directivity model consists of two tuning vectors corresponding to the spacing error and the weight error for the primary frequency. The directivity model adopts a modified form of the product directivity principle for the difference frequency to further improve the modeling accuracy.

  16. Observational Signatures of Parametric Instability at 1AU

    NASA Astrophysics Data System (ADS)

    Bowen, T. A.; Bale, S. D.; Badman, S.

    2017-12-01

    Observations and simulations of inertial compressive turbulence in the solar wind are characterized by density structures anti-correlated with magnetic fluctuations parallel to the mean field. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures (PBS), kinetic ion acoustic waves, as well as the MHD slow mode. Recent work, specifically Verscharen et al. (2017), has highlighted the unexpected fluid like nature of the solar wind. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggests the presence of a driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the parametric instability, in which large amplitude Alfvenic fluctuations decay into parallel propagating compressive waves. This work employs 10 years of WIND observations in order to test the parametric decay process as a source of compressive waves in the solar wind through comparing collisionless damping rates of compressive fluctuations with growth rates of the parametric instability. Preliminary results suggest that generation of compressive waves through parametric decay is overdamped at 1 AU. However, the higher parametric decay rates expected in the inner heliosphere likely allow for growth of the slow mode-the remnants of which could explain density fluctuations observed at 1AU.

  17. Identifying context-specific competencies required by community Australian Football sports trainers.

    PubMed

    Donaldson, Alex; Finch, Caroline F

    2012-08-01

    First-aid is a recommended injury prevention and risk management strategy in community sport; however, little is known about the sport-specific competencies required by first-aid providers. To achieve expert consensus on the competencies required by community Australian Football (community-AF) sports trainers. A three-round online Delphi process. Community-AF. 16 Australian sports first-aid and community-AF experts. Rating of competencies as either 'essential', 'expected', 'ideal' or 'not required'. Results After Round 3, 47 of the 77 (61%) competencies were endorsed as 'essential' or 'expected' for a sports trainer to effectively perform the activities required to the standards expected at a community-AF club by ≥75% of experts. These competencies covered: the role of the sports trainer; the responsibilities of the sports trainer; emergency management; injury and illness assessment and immediate management; taping; and injury prevention and risk management. Four competencies (5%) were endorsed as 'ideal' or 'not required' by ≥85% of experts and were excluded from further consideration. The 26 competencies where consensus was not reached were retained as second-tier, optional competencies. Sports trainers are important members of on-field first-aid teams, providing support to both injured players and other sports medicine professionals. The competencies identified in this study provide the basis of a proposed two-tiered community-AF-specific sports trainer education structure that can be implemented by the peak sports body. This includes six mandatory modules, relating to the 'required' competencies, and a further six optional modules covering competencies on which consensus was not reached.

  18. Children, Gillick competency and consent for involvement in research

    PubMed Central

    Hunter, David; Pierscionek, Barbara K

    2007-01-01

    This paper looks at the issue of consent from children and whether the test of Gillick competency, applied in medical and healthcare practice, ought to extend to participation in research. It is argued that the relatively broad usage of the test of Gillick competency in the medical context should not be considered applicable for use in research. The question of who would and could determine Gillick competency in research raises further concerns relating to the training of the researcher to make such a decision as well as to the obvious issue of the researcher's personal interest in the project and possibility of benefiting from the outcome. These could affect the judgment of Gillick competency if the researcher is charged with making this decision. The above notwithstanding, there are two exceptional research situations in which Gillick competency might be legitimately applied: (1) when the research is likely to generate significant advantages for the participants while exposing them to relatively minor risks, and (2) when it is likely to generate great societal benefit, pose minimal risks for the participants and yet raise parental objection. In both cases, to ensure that autonomy is genuinely respected and to protect against personal interest, Gillick competency should be assessed by an individual who has no interest or involvement in the research. PMID:17971470

  19. The degenerate parametric oscillator and Ince's equation

    NASA Astrophysics Data System (ADS)

    Cordero-Soto, Ricardo; Suslov, Sergei K.

    2011-01-01

    We construct Green's function for the quantum degenerate parametric oscillator in the coordinate representation in terms of standard solutions of Ince's equation in a framework of a general approach to variable quadratic Hamiltonians. Exact time-dependent wavefunctions and their connections with dynamical invariants and SU(1, 1) group are also discussed. An extension to the degenerate parametric oscillator with time-dependent amplitude and phase is also mentioned.

  20. Stochastic stability of parametrically excited random systems

    NASA Astrophysics Data System (ADS)

    Labou, M.

    2004-01-01

    Multidegree-of-freedom dynamic systems subjected to parametric excitation are analyzed for stochastic stability. The variation of excitation intensity with time is described by the sum of a harmonic function and a stationary random process. The stability boundaries are determined by the stochastic averaging method. The effect of random parametric excitation on the stability of trivial solutions of systems of differential equations for the moments of phase variables is studied. It is assumed that the frequency of harmonic component falls within the region of combination resonances. Stability conditions for the first and second moments are obtained. It turns out that additional parametric excitation may have a stabilizing or destabilizing effect, depending on the values of certain parameters of random excitation. As an example, the stability of a beam in plane bending is analyzed.

  1. ESHOL study reanalysis: All-cause mortality considered by competing risks and time-dependent covariates for renal transplantation.

    PubMed

    Maduell, Francisco; Moreso, Francesc; Mora-Macià, Josep; Pons, Mercedes; Ramos, Rosa; Carreras, Jordi; Soler, Jordi; Torres, Ferrán

    2016-01-01

    The ESHOL study showed that post-dilution online haemodiafiltration (OL-HDF) reduces all-cause mortality versus haemodialysis. However, during the observation period, 355 patients prematurely completed the study and, according to the study design, these patients were censored at the time of premature termination. The aim of this study was to investigate the outcome of patients who discontinued the study. During follow-up, 207 patients died while under treatment and 47 patients died after discontinuation of the study. Compared with patients maintained on haemodialysis, those randomised to OL-HDF had lower all-cause mortality (12.4 versus 9.46 per 100 patient-years, hazard ratio and 95%CI: 0.76; [0.59-0.98], P= 0.031). For all-cause mortality by time-dependent covariates and competing risks for transplantation, the time-dependent Cox analysis showed very similar results to the main analysis with a hazard ratio of 0.77 (0.60-0.99, P= 0.043). The results of this analysis of the ESHOL trial confirm that post-dilution OL-HDF reduces all-cause mortality versus haemodialysis in prevalent patients. The original results of the ESHOL study, which censored patients discontinuing the study for any reason, were confirmed in the present ITT population without censures and when all-cause mortality was considered by time-dependent and competing risks for transplantation. Copyright © 2015 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

  2. Rayleigh-type parametric chemical oscillation.

    PubMed

    Ghosh, Shyamolina; Ray, Deb Shankar

    2015-09-28

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

  3. Childhood Predictors of Adolescent Competence and Self-Worth in Rural Youth

    PubMed Central

    Rew, Lynn; Grady, Matthew W.; Spoden, Micajah

    2012-01-01

    Problem Urban children who become competent adults despite circumstances that place their development and mental health at risk are considered to be resilient. Less is known about the risk and protective factors that characterize resilience among Hispanic/Latinos living in rural areas. Methods Data for regression analyses were collected when children (N = 603; 54% Hispanic/Latino) enrolled in the study in fifth grade, (M=10.4 years of age) and again five years later when they were in high school (M=15 years of age). Findings Statistically significant predictors of competence and self-worth in high schoolers included gender, ethnicity, and mother’s education, as well as stress, temperament (task persistence), and competences measured in grade school. Conclusions Parents’ perceptions of child’s temperament is a significant predictor of future competence and self-worth among rural adolescents. PMID:23121139

  4. Childhood predictors of adolescent competence and self-worth in rural youth.

    PubMed

    Rew, Lynn; Grady, Matthew W; Spoden, Micajah

    2012-11-01

    Urban children who become competent adults despite circumstances that place their development and mental health at risk are considered to be resilient. Less is known about the risk and protective factors that characterize resilience among Hispanic/Latinos living in rural areas. Data for regression analyses were collected when children (n = 603; 54% Hispanic/Latino) enrolled in the study in fifth grade (M = 10.4 years of age), and again 5 years later when they were in high school (M = 15 years of age). Statistically significant predictors of competence and self-worth in high schoolers included gender, ethnicity, and mother's education, as well as stress, temperament (task persistence), and competences measured in grade school. Parents' perception of child's temperament is a significant predictor of future competence and self-worth among rural adolescents. © 2012 Wiley Periodicals, Inc.

  5. Parametric amplification in a resonant sensing array

    NASA Astrophysics Data System (ADS)

    Yie, Zi; Miller, Nicholas J.; Shaw, Steven W.; Turner, Kimberly L.

    2012-03-01

    We demonstrate parametric amplification of a multidegree of freedom resonant mass sensing array via an applied base motion containing the appropriate frequency content and phases. Applying parametric forcing in this manner is simple and aligns naturally with the vibrational properties of the sensing structure. Using this technique, we observe an increase in the quality factors of the coupled array resonances, which provides an effective means of improving device sensitivity.

  6. Towards an Empirically Based Parametric Explosion Spectral Model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ford, S R; Walter, W R; Ruppert, S

    2009-08-31

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before been tested. The focus of our work is on the local and regional distances (< 2000 km) and phases (Pn, Pg, Sn, Lg) necessary to see small explosions. We are developing a parametric model of the nuclear explosion seismic source spectrum that is compatible with the earthquake-based geometrical spreading and attenuation models developed using the Magnitude Distance Amplitude Correction (MDAC) techniques (Walter and Taylor, 2002). The explosion parametric model will be particularly important in regions without any priormore » explosion data for calibration. The model is being developed using the available body of seismic data at local and regional distances for past nuclear explosions at foreign and domestic test sites. Parametric modeling is a simple and practical approach for widespread monitoring applications, prior to the capability to carry out fully deterministic modeling. The achievable goal of our parametric model development is to be able to predict observed local and regional distance seismic amplitudes for event identification and yield determination in regions with incomplete or no prior history of underground nuclear testing. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.« less

  7. A capacitive ultrasonic transducer based on parametric resonance.

    PubMed

    Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F

    2017-07-24

    A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f o . When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f o with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f o frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

  8. Risk factors for reporting poor cultural competency among patients with diabetes in safety net clinics.

    PubMed

    Seligman, Hilary K; Fernandez, Alicia; Stern, Rachel J; Weech-Maldonado, Robert; Quan, Judy; Jacobs, Elizabeth A

    2012-09-01

    The Consumer Assessment of Healthcare Providers and Systems Cultural Competency Item Set assesses patient perceptions of aspects of the cultural competence of their health care. To determine characteristics of patients who identify the care they receive as less culturally competent. Cross-sectional survey consisting of face-to-face interviews. Safety-net population of patients with type 2 diabetes (n=600) receiving ongoing primary care. Participants completed the Consumer Assessment of Healthcare Providers and Systems Cultural Competency and answered questions about their race/ethnicity, sex, age, education, health status, depressive symptoms, insurance coverage, English proficiency, duration of relationship with primary care provider, and comorbidities. In adjusted models, depressive symptoms were significantly associated with poor cultural competency in the Doctor Communication--Positive Behaviors domain [odds ratio (OR) 1.73, 95% confidence interval, 1.11-2.69]. African Americans were less likely than whites to report poor cultural competence in the Doctor Communication--Positive Behaviors domain (OR 0.52, 95% CI, 0.28-0.97). Participants who reported a longer relationship (≥ 3 y) with their primary care provider were less likely to report poor cultural competence in the Doctor Communication--Health Promotion (OR 0.35, 95% CI, 0.21-0.60) and Trust domains (OR 0.4, 95% CI, 0.24-0.67), whereas participants with lower educational attainment were less likely to report poor cultural competence in the Trust domain (OR 0.51, 95% CI, 0.30-0.86). Overall, however, sociodemographic and clinical differences in reports of poor cultural competence were insignificant or inconsistent across the various domains of cultural competence examined. Cultural competence interventions in safety-net settings should be implemented across populations, rather than being narrowly focused on specific sociodemographic or clinical groups.

  9. Addressing missing covariates for the regression analysis of competing risks: Prognostic modelling for triaging patients diagnosed with prostate cancer.

    PubMed

    Escarela, Gabriel; Ruiz-de-Chavez, Juan; Castillo-Morales, Alberto

    2016-08-01

    Competing risks arise in medical research when subjects are exposed to various types or causes of death. Data from large cohort studies usually exhibit subsets of regressors that are missing for some study subjects. Furthermore, such studies often give rise to censored data. In this article, a carefully formulated likelihood-based technique for the regression analysis of right-censored competing risks data when two of the covariates are discrete and partially missing is developed. The approach envisaged here comprises two models: one describes the covariate effects on both long-term incidence and conditional latencies for each cause of death, whilst the other deals with the observation process by which the covariates are missing. The former is formulated with a well-established mixture model and the latter is characterised by copula-based bivariate probability functions for both the missing covariates and the missing data mechanism. The resulting formulation lends itself to the empirical assessment of non-ignorability by performing sensitivity analyses using models with and without a non-ignorable component. The methods are illustrated on a 20-year follow-up involving a prostate cancer cohort from the National Cancer Institutes Surveillance, Epidemiology, and End Results program. © The Author(s) 2013.

  10. Competence profiles in undergraduate dental education: a comparison between theory and reality.

    PubMed

    Koole, Sebastiaan; Van Den Brulle, Shani; Christiaens, Véronique; Jacquet, Wolfgang; Cosyn, Jan; De Bruyn, Hugo

    2017-07-11

    Competence profiles are purposed to provide a blueprint in support to develop and/or benchmark the learning outcomes of undergraduate dental curricula. This study aims to investigate whether a competence profile as proposed by academic- and clinical experts is able to represent the real clinical reality. A questionnaire was developed including questions about gender and age, perception about required competences, and educational organisation and was distributed among Flemish dentists via email and on paper during a symposium. The data was analysed using descriptive statistics, Chi-square and non-parametric Mann-Whitney U-tests. A total of 312 questionnaires were completed (=6.5% of dentist population, with similar gender and age characteristics). All competences in the European competence profile were rated between 7.2 and 9.4 on a 10-point scale. In dentists under 50 years, females rated the importance of identifying/managing anxiety and abnormal patient behaviour; and promoting/improving oral health as significantly higher than males. In dentists of 50 years and above, females rated 8 competences significantly higher than males, including obtaining/recording a complete history; identifying/managing anxiety and abnormal patient behaviour; obtaining/interpreting radiography; identifying temporomandibular and associated disorders; identifying orthodontic needs; awareness of own limitations/when to refer; managing dental urgencies; and basic-life-support/defibrillation. Clinical practice management was most frequently reported as additional competence to address in dental education. Furthermore, the respondents suggested an undergraduate dental curriculum based on 34% theoretical education, 26% preclinical skills training, and 40% clinical education and 86% agreed with a duration of 5 years. Finally, the respondents also illustrated the dynamic nature of dentistry including a reduction of amalgam fillings, a shift from individual practice to group practices, an

  11. Modeling personnel turnover in the parametric organization

    NASA Technical Reports Server (NTRS)

    Dean, Edwin B.

    1991-01-01

    A model is developed for simulating the dynamics of a newly formed organization, credible during all phases of organizational development. The model development process is broken down into the activities of determining the tasks required for parametric cost analysis (PCA), determining the skills required for each PCA task, determining the skills available in the applicant marketplace, determining the structure of the model, implementing the model, and testing it. The model, parameterized by the likelihood of job function transition, has demonstrated by the capability to represent the transition of personnel across functional boundaries within a parametric organization using a linear dynamical system, and the ability to predict required staffing profiles to meet functional needs at the desired time. The model can be extended by revisions of the state and transition structure to provide refinements in functional definition for the parametric and extended organization.

  12. A Parametric Oscillator Experiment for Undergraduates

    NASA Astrophysics Data System (ADS)

    Huff, Alison; Thompson, Johnathon; Pate, Jacob; Kim, Hannah; Chiao, Raymond; Sharping, Jay

    We describe an upper-division undergraduate-level analytic mechanics experiment or classroom demonstration of a weakly-damped pendulum driven into parametric resonance. Students can derive the equations of motion from first principles and extract key oscillator features, such as quality factor and parametric gain, from experimental data. The apparatus is compact, portable and easily constructed from inexpensive components. Motion control and data acquisition are accomplished using an Arduino micro-controller incorporating a servo motor, laser sensor, and data logger. We record the passage time of the pendulum through its equilibrium position and obtain the maximum speed per oscillation as a function of time. As examples of the interesting physics which the experiment reveals, we present contour plots depicting the energy of the system as functions of driven frequency and modulation depth. We observe the transition to steady state oscillation and compare the experimental oscillation threshold with theoretical expectations. A thorough understanding of this hands-on laboratory exercise provides a foundation for current research in quantum information and opto-mechanics, where damped harmonic motion, quality factor, and parametric amplification are central.

  13. Parametric Cost Models for Space Telescopes

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtney

    2010-01-01

    Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.

  14. 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

  15. The impact of parametrized convection on cloud feedback.

    PubMed

    Webb, Mark J; Lock, Adrian P; Bretherton, Christopher S; Bony, Sandrine; Cole, Jason N S; Idelkadi, Abderrahmane; Kang, Sarah M; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D; Zhao, Ming

    2015-11-13

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that 'ConvOff' models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback

  16. Machine learning-based dual-energy CT parametric mapping

    NASA Astrophysics Data System (ADS)

    Su, Kuan-Hao; Kuo, Jung-Wen; Jordan, David W.; Van Hedent, Steven; Klahr, Paul; Wei, Zhouping; Helo, Rose Al; Liang, Fan; Qian, Pengjiang; Pereira, Gisele C.; Rassouli, Negin; Gilkeson, Robert C.; Traughber, Bryan J.; Cheng, Chee-Wai; Muzic, Raymond F., Jr.

    2018-06-01

    The aim is to develop and evaluate machine learning methods for generating quantitative parametric maps of effective atomic number (Zeff), relative electron density (ρ e), mean excitation energy (I x ), and relative stopping power (RSP) from clinical dual-energy CT data. The maps could be used for material identification and radiation dose calculation. Machine learning methods of historical centroid (HC), random forest (RF), and artificial neural networks (ANN) were used to learn the relationship between dual-energy CT input data and ideal output parametric maps calculated for phantoms from the known compositions of 13 tissue substitutes. After training and model selection steps, the machine learning predictors were used to generate parametric maps from independent phantom and patient input data. Precision and accuracy were evaluated using the ideal maps. This process was repeated for a range of exposure doses, and performance was compared to that of the clinically-used dual-energy, physics-based method which served as the reference. The machine learning methods generated more accurate and precise parametric maps than those obtained using the reference method. Their performance advantage was particularly evident when using data from the lowest exposure, one-fifth of a typical clinical abdomen CT acquisition. The RF method achieved the greatest accuracy. In comparison, the ANN method was only 1% less accurate but had much better computational efficiency than RF, being able to produce parametric maps in 15 s. Machine learning methods outperformed the reference method in terms of accuracy and noise tolerance when generating parametric maps, encouraging further exploration of the techniques. Among the methods we evaluated, ANN is the most suitable for clinical use due to its combination of accuracy, excellent low-noise performance, and computational efficiency.

  17. Machine learning-based dual-energy CT parametric mapping.

    PubMed

    Su, Kuan-Hao; Kuo, Jung-Wen; Jordan, David W; Van Hedent, Steven; Klahr, Paul; Wei, Zhouping; Al Helo, Rose; Liang, Fan; Qian, Pengjiang; Pereira, Gisele C; Rassouli, Negin; Gilkeson, Robert C; Traughber, Bryan J; Cheng, Chee-Wai; Muzic, Raymond F

    2018-06-08

    The aim is to develop and evaluate machine learning methods for generating quantitative parametric maps of effective atomic number (Z eff ), relative electron density (ρ e ), mean excitation energy (I x ), and relative stopping power (RSP) from clinical dual-energy CT data. The maps could be used for material identification and radiation dose calculation. Machine learning methods of historical centroid (HC), random forest (RF), and artificial neural networks (ANN) were used to learn the relationship between dual-energy CT input data and ideal output parametric maps calculated for phantoms from the known compositions of 13 tissue substitutes. After training and model selection steps, the machine learning predictors were used to generate parametric maps from independent phantom and patient input data. Precision and accuracy were evaluated using the ideal maps. This process was repeated for a range of exposure doses, and performance was compared to that of the clinically-used dual-energy, physics-based method which served as the reference. The machine learning methods generated more accurate and precise parametric maps than those obtained using the reference method. Their performance advantage was particularly evident when using data from the lowest exposure, one-fifth of a typical clinical abdomen CT acquisition. The RF method achieved the greatest accuracy. In comparison, the ANN method was only 1% less accurate but had much better computational efficiency than RF, being able to produce parametric maps in 15 s. Machine learning methods outperformed the reference method in terms of accuracy and noise tolerance when generating parametric maps, encouraging further exploration of the techniques. Among the methods we evaluated, ANN is the most suitable for clinical use due to its combination of accuracy, excellent low-noise performance, and computational efficiency.

  18. The impact of parametrized convection on cloud feedback

    PubMed Central

    Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming

    2015-01-01

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud

  19. Direct Estimation of Kinetic Parametric Images for Dynamic PET

    PubMed Central

    Wang, Guobao; Qi, Jinyi

    2013-01-01

    Dynamic positron emission tomography (PET) can monitor spatiotemporal distribution of radiotracer in vivo. The spatiotemporal information can be used to estimate parametric images of radiotracer kinetics that are of physiological and biochemical interests. Direct estimation of parametric images from raw projection data allows accurate noise modeling and has been shown to offer better image quality than conventional indirect methods, which reconstruct a sequence of PET images first and then perform tracer kinetic modeling pixel-by-pixel. Direct reconstruction of parametric images has gained increasing interests with the advances in computing hardware. Many direct reconstruction algorithms have been developed for different kinetic models. In this paper we review the recent progress in the development of direct reconstruction algorithms for parametric image estimation. Algorithms for linear and nonlinear kinetic models are described and their properties are discussed. PMID:24396500

  20. Student diversity and implications for clinical competency development amongst domestic and international speech-language pathology students.

    PubMed

    Attrill, Stacie; Lincoln, Michelle; McAllister, Sue

    2012-06-01

    International students graduating from speech-language pathology university courses must achieve the same minimum competency standards as domestic students. This study aimed to collect descriptive information about the number, origin, and placement performance of international students as well as perceptions of the performance of international students on placement. University Clinical Education Coordinators (CECs), who manage clinical placements in eight undergraduate and six graduate entry programs across the 10 participating universities in Australia and New Zealand completed a survey about 3455 international and domestic speech-language pathology students. Survey responses were analysed quantitatively and qualitatively with non-parametric statistics and thematic analysis. Results indicated that international students came from a variety of countries, but with a regional focus on the countries of Central and Southern Asia. Although domestic students were noted to experience significantly less placement failure, fewer supplementary placements, and reduced additional placement support than international students, the effect size of these relationships was consistently small and therefore weak. CECs rated international students as more frequently experiencing difficulties with communication competencies on placement. However, CECs qualitative comments revealed that culturally and linguistically diverse (CALD) students may experience more difficulties with speech-language pathology competency development than international students. Students' CALD status should be included in future investigations of factors influencing speech-language pathology competency development.

  1. Implementing quantum optics with parametrically driven superconducting circuits

    NASA Astrophysics Data System (ADS)

    Aumentado, Jose

    Parametric coupling has received much attention, in part because it forms the core of many low-noise amplifiers in superconducting quantum information experiments. However, parametric coupling in superconducting circuits is, as a general rule, simple to generate and forms the basis of a methodology for interacting microwave fields at different frequencies. In the quantum regime, this has important consequences, allowing relative novices to do experiments in superconducting circuits today that were previously heroic efforts in quantum optics and cavity-QED. In this talk, I'll give an overview of some of our work demonstrating parametric coupling within the context of circuit-QED as well as some of the possibilities this concept creates in our field.

  2. Greater decision-making competence is associated with greater expected-value sensitivity, but not overall risk taking: an examination of concurrent validity.

    PubMed

    Parker, Andrew M; Weller, Joshua A

    2015-01-01

    Decision-making competence reflects individual differences in the susceptibility to committing decision-making errors, measured using tasks common from behavioral decision research (e.g., framing effects, under/overconfidence, following decision rules). Prior research demonstrates that those with higher decision-making competence report lower incidence of health-risking and antisocial behaviors, but there has been less focus on intermediate processes that may impact real-world decisions, and, in particular, those implicated by normative models. Here we test the associations between measures of youth decision-making competence (Y-DMC) and one such process, the degree to which individuals make choices consistent with maximizing expected value (EV). Using a task involving hypothetical gambles, we find that greater EV sensitivity is associated with greater Y-DMC. Higher Y-DMC scores are associated with (a) choosing risky options when EV favors those options and (b) avoiding risky options when EV favors a certain option. This relationship is stronger for gambles that involved potential losses. The results suggest that Y-DMC captures decision processes consistent with standard normative evaluations of risky decisions.

  3. Parametric instabilities of rotor-support systems with application to industrial ventilators

    NASA Technical Reports Server (NTRS)

    Parszewski, Z.; Krodkiemski, T.; Marynowski, K.

    1980-01-01

    Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.

  4. Risk Factors for Reporting Poor Cultural Competency Among Patients with Diabetes in Safety-Net Clinics

    PubMed Central

    Seligman, Hilary K.; Fernandez, Alicia; Stern, Rachel J.; Weech-Maldonado, Robert; Quan, Judy; Jacobs, Elizabeth A.

    2012-01-01

    Background The Consumer Assessment of Healthcare Providers and Systems Cultural Competency (CAHPS-CC) Item Set assesses patient perceptions of aspects of the cultural competence of their health care. Objective To determine characteristics of patients who identify the care they receive as less culturally competent Research Design Cross-sectional survey consisting of face-to-face interviews Subjects Safety-net population of patients with type 2 diabetes (n=600) receiving ongoing primary care Measures Participants completed the CAHPS-CC and answered questions about their race/ethnicity, gender, age, education, health status, depressive symptoms, insurance coverage, English proficiency, duration of relationship with primary care provider, and co-morbidities. Results In adjusted models, depressive symptoms were significantly associated with poor cultural competency in the Doctor Communication – Positive Behaviors domain (OR 1.73, 95%CI 1.11, 2.69). African-Americans were less likely than Whites to report poor cultural competence in the Doctor Communication – Positive Behaviors domain (OR 0.52, 0.28–0.97). Participants who reported a longer relationship (≥3 years) with their primary care provider were less likely to report poor cultural competence in the Doctor Communication – Health Promotion (OR 0.35, 0.21–0.60) and Trust domains (OR 0.4, 0.24–0.67), while participants with lower educational attainment were less likely to report poor cultural competence in the Trust domain (OR 0.51, 0.30–0.86). Overall, however, sociodemographic and clinical differences in reports of poor cultural competence were insignificant or inconsistent across the various domains of cultural competence examined. Conclusions Cultural competence interventions in safety-net settings should be implemented across populations, rather than being narrowly focused on specific sociodemographic or clinical groups. PMID:22895232

  5. Problems of the design of low-noise input devices. [parametric amplifiers

    NASA Technical Reports Server (NTRS)

    Manokhin, V. M.; Nemlikher, Y. A.; Strukov, I. A.; Sharfov, Y. A.

    1974-01-01

    An analysis is given of the requirements placed on the elements of parametric centimeter waveband amplifiers for achievement of minimal noise temperatures. A low-noise semiconductor parametric amplifier using germanium parametric diodes for a receiver operating in the 4 GHz band was developed and tested confirming the possibility of satisfying all requirements.

  6. The social competence of Latino kindergartners and growth in mathematical understanding.

    PubMed

    Galindo, Claudia; Fuller, Bruce

    2010-05-01

    We know that social competence contributes to young children's adaptation to, and cognitive learning within, classroom settings. Yet initial evidence is mixed on the social competencies that Latino children bring to kindergarten and the extent to which these skills advance cognitive growth. Building from ecocultural and developmental-risk theory, this paper shows children's social competence to be adaptive to the normative expectations and cognitive requirements of culturally bounded settings in both the home and classroom. Latino socialization in the home may yield social competencies that teachers value rather than reflect "risk factors" that constrain children's school readiness. We draw on the Early Childhood Longitudinal Study, kindergarten cohort (N = 19,590) to detail 5 social competencies at entry to school--self-control, interpersonal skills, approaches to learning, internalizing and externalizing problem behaviors--and to examine variability among Latino subgroups. We then test the extent to which baseline variation in social competence accounts for children's cognitive growth during the kindergarten year. We find that Latino children from poor, but not middle-class, families display weaker social competencies vis-à-vis White children (all relationships p < or = .05). Social competence levels contribute to Latino children's cognitive growth, which is shaped most strongly by positive approaches to learning. The disparities in competencies observed for Latino children from poor families, relative to White children, are significant yet much smaller than gaps in baseline levels of mathematical understanding. We discuss how the consonance or mismatch between competencies acquired at home and those valued by teachers must consider cultural differences, social-class position, and variation among diverse Latino subgroups. 2010 APA, all rights reserved

  7. Noise-enhanced Parametric Resonance in Perturbed Galaxies

    NASA Astrophysics Data System (ADS)

    Sideris, Ioannis V.; Kandrup, Henry E.

    2004-02-01

    This paper describes how parametric resonances associated with a galactic potential subjected to relatively low-amplitude, strictly periodic time-dependent perturbations can be impacted by pseudo-random variations in the pulsation frequency, modeled as colored noise. One aim thereby is to allow for the effects of a changing oscillation frequency as the density distribution associated with a galaxy evolves during violent relaxation. Another is to mimic the possible effects of internal substructures, satellite galaxies, and/or a high-density environment. The principal conclusions are that allowing for a variable frequency does not vitiate the effects of parametric resonance, and that, in at least some cases, such variations can increase the overall importance of parametric resonance associated with systematic pulsations. In memory of Professor H. E. Kandrup, a brilliant scientist, excellent teacher, and good friend. His genius and sense of humor will be greatly missed.

  8. Josephson Parametric Reflection Amplifier with Integrated Directionality

    NASA Astrophysics Data System (ADS)

    Westig, M. P.; Klapwijk, T. M.

    2018-06-01

    A directional superconducting parametric amplifier in the GHz frequency range is designed and analyzed, suitable for low-power read-out of microwave kinetic inductance detectors employed in astrophysics and when combined with a nonreciprocal device at its input also for circuit quantum electrodynamics. It consists of a one-wavelength-long nondegenerate Josephson parametric reflection amplifier circuit. The device has two Josephson-junction oscillators, connected via a tailored impedance to an on-chip passive circuit which directs the in- to the output port. The amplifier provides a gain of 20 dB over a bandwidth of 220 MHz on the signal as well as on the idler portion of the amplified input and the total photon shot noise referred to the input corresponds to maximally approximately 1.3 photons per second per Hertz of bandwidth. We predict a factor of 4 increase in dynamic range compared to conventional Josephson parametric amplifiers.

  9. Quantization of simple parametrized systems

    NASA Astrophysics Data System (ADS)

    Ruffini, G.

    2005-11-01

    I study the canonical formulation and quantization of some simple parametrized systems, including the non-relativistic parametrized particle and the relativistic parametrized particle. Using Dirac's formalism I construct for each case the classical reduced phase space and study the dependence on the gauge fixing used. Two separate features of these systems can make this construction difficult: the actions are not invariant at the boundaries, and the constraints may have disconnected solution spaces. The relativistic particle is affected by both, while the non-relativistic particle displays only by the first. Analyzing the role of canonical transformations in the reduced phase space, I show that a change of gauge fixing is equivalent to a canonical transformation. In the relativistic case, quantization of one branch of the constraint at the time is applied and I analyze the electromagenetic backgrounds in which it is possible to quantize simultaneously both branches and still obtain a covariant unitary quantum theory. To preserve unitarity and space-time covariance, second quantization is needed unless there is no electric field. I motivate a definition of the inner product in all these cases and derive the Klein-Gordon inner product for the relativistic case. I construct phase space path integral representations for amplitudes for the BFV and the Faddeev path integrals, from which the path integrals in coordinate space (Faddeev-Popov and geometric path integrals) are derived.

  10. Melanoma-specific mortality and competing mortality in patients with non-metastatic malignant melanoma: a population-based analysis.

    PubMed

    Shen, Weidong; Sakamoto, Naoko; Yang, Limin

    2016-07-07

    The objectives of this study were to evaluate and model the probability of melanoma-specific death and competing causes of death for patients with melanoma by competing risk analysis, and to build competing risk nomograms to provide individualized and accurate predictive tools. Melanoma data were obtained from the Surveillance Epidemiology and End Results program. All patients diagnosed with primary non-metastatic melanoma during the years 2004-2007 were potentially eligible for inclusion. The cumulative incidence function (CIF) was used to describe the probability of melanoma mortality and competing risk mortality. We used Gray's test to compare differences in CIF between groups. The proportional subdistribution hazard approach by Fine and Gray was used to model CIF. We built competing risk nomograms based on the models that we developed. The 5-year cumulative incidence of melanoma death was 7.1 %, and the cumulative incidence of other causes of death was 7.4 %. We identified that variables associated with an elevated probability of melanoma-specific mortality included older age, male sex, thick melanoma, ulcerated cancer, and positive lymph nodes. The nomograms were well calibrated. C-indexes were 0.85 and 0.83 for nomograms predicting the probability of melanoma mortality and competing risk mortality, which suggests good discriminative ability. This large study cohort enabled us to build a reliable competing risk model and nomogram for predicting melanoma prognosis. Model performance proved to be good. This individualized predictive tool can be used in clinical practice to help treatment-related decision making.

  11. Acceleration of the direct reconstruction of linear parametric images using nested algorithms.

    PubMed

    Wang, Guobao; Qi, Jinyi

    2010-03-07

    Parametric imaging using dynamic positron emission tomography (PET) provides important information for biological research and clinical diagnosis. Indirect and direct methods have been developed for reconstructing linear parametric images from dynamic PET data. Indirect methods are relatively simple and easy to implement because the image reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from raw PET data and are statistically more efficient. However, the convergence rate of direct algorithms can be slow due to the coupling between the reconstruction and kinetic modeling. Here we present two fast gradient-type algorithms for direct reconstruction of linear parametric images. The new algorithms decouple the reconstruction and linear parametric modeling at each iteration by employing the principle of optimization transfer. Convergence speed is accelerated by running more sub-iterations of linear parametric estimation because the computation cost of the linear parametric modeling is much less than that of the image reconstruction. Computer simulation studies demonstrated that the new algorithms converge much faster than the traditional expectation maximization (EM) and the preconditioned conjugate gradient algorithms for dynamic PET.

  12. Parametric Amplifier and Oscillator Based on Josephson Junction Circuitry

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Koshino, K.; Nakamura, Y.

    While the demand for low-noise amplification is ubiquitous, applications where the quantum-limited noise performance is indispensable are not very common. Microwave parametric amplifiers with near quantum-limited noise performance were first demonstrated more than 20 years ago. However, there had been little effort until recently to improve the performance or the ease of use of these amplifiers, partly because of a lack of any urgent motivation. The emergence of the field of quantum information processing in superconducting systems has changed this situation dramatically. The need to reliably read out the state of a given qubit using a very weak microwave probe within a very short time has led to renewed interest in these quantum-limited microwave amplifiers, which are already widely used as tools in this field. Here, we describe the quantum mechanical theory for one particular parametric amplifier design, called the flux-driven Josephson parametric amplifier, which we developed in 2008. The theory predicts the performance of this parametric amplifier, including its gain, bandwidth, and noise temperature. We also present the phase detection capability of this amplifier when it is operated with a pump power that is above the threshold, i.e., as a parametric phase-locked oscillator or parametron.

  13. 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.

  14. Parametric number covariance in quantum chaotic spectra.

    PubMed

    Vinayak; Kumar, Sandeep; Pandey, Akhilesh

    2016-03-01

    We study spectral parametric correlations in quantum chaotic systems and introduce the number covariance as a measure of such correlations. We derive analytic results for the classical random matrix ensembles using the binary correlation method and obtain compact expressions for the covariance. We illustrate the universality of this measure by presenting the spectral analysis of the quantum kicked rotors for the time-reversal invariant and time-reversal noninvariant cases. A local version of the parametric number variance introduced earlier is also investigated.

  15. Parametric Amplification For Detecting Weak Optical Signals

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Chen, Chien; Chakravarthi, Prakash

    1996-01-01

    Optical-communication receivers of proposed type implement high-sensitivity scheme of optical parametric amplification followed by direct detection for reception of extremely weak signals. Incorporates both optical parametric amplification and direct detection into optimized design enhancing effective signal-to-noise ratios during reception in photon-starved (photon-counting) regime. Eliminates need for complexity of heterodyne detection scheme and partly overcomes limitations imposed on older direct-detection schemes by noise generated in receivers and by limits on quantum efficiencies of photodetectors.

  16. Optical parametric amplification and oscillation assisted by low-frequency stimulated emission.

    PubMed

    Longhi, Stefano

    2016-04-15

    Optical parametric amplification and oscillation provide powerful tools for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency down-conversion process and, thus, it cannot be realized for signal waves at a frequency ω3 higher than the frequency of the pump wave ω1. In this Letter, we suggest a route toward the realization of upconversion optical parametric amplification and oscillation, i.e., amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of upconversion optical parametric oscillation at λ3=465 nm are given for a periodically poled lithium-niobate (PPLN) crystal doped with Nd(3+) ions.

  17. [The role of "competent physician" for prevention of accidents at work].

    PubMed

    Ramistella, E; Bergamaschi, A; Mosconi, G; Rossi, O; Sallese, D

    2008-01-01

    Using at best the professional and legal tools at his/her disposal, the "competent physician" can have a relevant role in reducing accidents in the workplace. In assessing the worker's suitability to specific tasks, the competent physician checks the presence of pathologies or functional impairments of organs or apparatuses that can be an additional risk for the occurrence of accidents at work. The activity aimed to preventing accidents at work translates also in taking part in the planning and implementation of information activities and workers' training within the company. The various risk factors inherent in the workplace and so-called "human factors" can interact in a negative way to the point of becoming a cause of accidents. The human variables of accident risk at the industrial, occupational and even individual level, may be numerous. In this paper we shall review these important aspects and attempt to clarify the role that can be played by the competent physician in the prevention of accidents at work.

  18. Terahertz parametric sources and imaging applications

    NASA Astrophysics Data System (ADS)

    Kawase, Kodo; Ogawa, Yuichi; Minamide, Hiroaki; Ito, Hiromasa

    2005-07-01

    We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of LiNbO3 or MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave source with a simple configuration. We report the detailed characteristics of the oscillation and the radiation including tunability, spatial and temporal coherency, uni-directivity, and efficiency. A Fourier transform limited THz-wave spectrum narrowing was achieved by introducing the injection seeding method. Further, we have developed a spectroscopic THz imaging system using a THz-wave parametric oscillator, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis. Several images of the envelope are recorded at different THz frequencies and then processed. The final result is an image that reveals what substances are present in the envelope, in what quantity, and how they are distributed across the envelope area. The example presented here shows the identification of three drugs, two of which are illegal, while one is an over-the-counter drug.

  19. THz-wave parametric sources and imaging applications

    NASA Astrophysics Data System (ADS)

    Kawase, Kodo

    2004-12-01

    We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We have also developed a novel basic technology for THz imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral trasillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

  20. Self-competence Among Early and Middle Adolescents Affected by Maternal HIV/AIDS

    PubMed Central

    Marelich, William D.; Murphy, Debra A.; Payne, Diana L.; Herbeck, Diane M.; Schuster, Mark A.

    2012-01-01

    Adolescent children of mothers with HIV face a host of stressors that place them at increased risk for poor outcomes. Using covariance structure analysis, this study examines adolescent risk outcomes and their relationships to maternal health, as well as the potentially protective factors of family environment and self-competence. The final model indicated that poor maternal health was negatively related to a protective family environment, which in turn was negatively related to adolescent risk outcomes. A protective family environment was also positively related to adolescent self-competence, which was negatively related to adolescent risk outcomes. Implications of the study are discussed, including how these findings can influence interventions aimed at reducing the risk for poor outcomes among adolescent youth with HIV-infected mothers. PMID:22485061

  1. Risk factors for competing noncancer mortality after definitive treatment for advanced-stage head and neck cancer.

    PubMed

    Kim, Yong Han; Roh, Jong-Lyel; Kim, Sung-Bae; Choi, Seung-Ho; Nam, Soon Yuhl; Kim, Sang Yoon

    2018-05-27

    Patients with head and neck cancer (HNC) can die of index tumor progression and second tumor or noncancer causes. Here, we investigated the risk factors for competing noncancer mortality (NCM) in a prospective cohort of patients with advanced-stage HNC. A prospective observational study was conducted with 604 patients who underwent definitive treatment for advanced-stage HNC between 2010 and 2015. Main outcomes were NCM and cancer mortality (CM) defined as death from noncancer causes and HNC or second cancers, respectively. Cumulative incidence and cause-specific hazard functions were used to analyze the risk factors of NCM and CM. Age, smoking, Charlson comorbidity index (CCI), performance status, body mass index, rural residence, education and hemoglobin level at diagnosis, and chemotherapy were significantly associated with NCM (all P<0.05). Multivariate analyses showed that age, CCI, and hemoglobin were independent factors of NCM. Age (≥65 years), CCI (≥2), and hemoglobin (<11 g/dL) were related to 4.5-, 3.2-, and 2.7-fold increased adjusted risk of NCM, respectively. Old age, comorbidity, and hemoglobin at diagnosis were independent predictors of NCM. The risk factors could be used to predict noncancer death after definitive treatment for advanced-stage HNC. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

    NASA Astrophysics Data System (ADS)

    Koutserimpas, Theodoros T.; Alù, Andrea; Fleury, Romain

    2018-01-01

    Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

  3. Parametric Modelling of As-Built Beam Framed Structure in Bim Environment

    NASA Astrophysics Data System (ADS)

    Yang, X.; Koehl, M.; Grussenmeyer, P.

    2017-02-01

    A complete documentation and conservation of a historic timber roof requires the integration of geometry modelling, attributional and dynamic information management and results of structural analysis. Recently developed as-built Building Information Modelling (BIM) technique has the potential to provide a uniform platform, which provides possibility to integrate the traditional geometry modelling, parametric elements management and structural analysis together. The main objective of the project presented in this paper is to develop a parametric modelling tool for a timber roof structure whose elements are leaning and crossing beam frame. Since Autodesk Revit, as the typical BIM software, provides the platform for parametric modelling and information management, an API plugin, able to automatically create the parametric beam elements and link them together with strict relationship, was developed. The plugin under development is introduced in the paper, which can obtain the parametric beam model via Autodesk Revit API from total station points and terrestrial laser scanning data. The results show the potential of automatizing the parametric modelling by interactive API development in BIM environment. It also integrates the separate data processing and different platforms into the uniform Revit software.

  4. Multi-parametric centrality method for graph network models

    NASA Astrophysics Data System (ADS)

    Ivanov, Sergei Evgenievich; Gorlushkina, Natalia Nikolaevna; Ivanova, Lubov Nikolaevna

    2018-04-01

    The graph model networks are investigated to determine centrality, weights and the significance of vertices. For centrality analysis appliesa typical method that includesany one of the properties of graph vertices. In graph theory, methods of analyzing centrality are used: in terms by degree, closeness, betweenness, radiality, eccentricity, page-rank, status, Katz and eigenvector. We have proposed a new method of multi-parametric centrality, which includes a number of basic properties of the network member. The mathematical model of multi-parametric centrality method is developed. Comparison of results for the presented method with the centrality methods is carried out. For evaluate the results for the multi-parametric centrality methodthe graph model with hundreds of vertices is analyzed. The comparative analysis showed the accuracy of presented method, includes simultaneously a number of basic properties of vertices.

  5. Probabilistic Evaluation of Competing Climate Models

    NASA Astrophysics Data System (ADS)

    Braverman, A. J.; Chatterjee, S.; Heyman, M.; Cressie, N.

    2017-12-01

    A standard paradigm for assessing the quality of climate model simulations is to compare what these models produce for past and present time periods, to observations of the past and present. Many of these comparisons are based on simple summary statistics called metrics. Here, we propose an alternative: evaluation of competing climate models through probabilities derived from tests of the hypothesis that climate-model-simulated and observed time sequences share common climate-scale signals. The probabilities are based on the behavior of summary statistics of climate model output and observational data, over ensembles of pseudo-realizations. These are obtained by partitioning the original time sequences into signal and noise components, and using a parametric bootstrap to create pseudo-realizations of the noise sequences. The statistics we choose come from working in the space of decorrelated and dimension-reduced wavelet coefficients. We compare monthly sequences of CMIP5 model output of average global near-surface temperature anomalies to similar sequences obtained from the well-known HadCRUT4 data set, as an illustration.

  6. The robust corrective action priority-an improved approach for selecting competing corrective actions in FMEA based on principle of robust design

    NASA Astrophysics Data System (ADS)

    Sutrisno, Agung; Gunawan, Indra; Vanany, Iwan

    2017-11-01

    In spite of being integral part in risk - based quality improvement effort, studies improving quality of selection of corrective action priority using FMEA technique are still limited in literature. If any, none is considering robustness and risk in selecting competing improvement initiatives. This study proposed a theoretical model to select risk - based competing corrective action by considering robustness and risk of competing corrective actions. We incorporated the principle of robust design in counting the preference score among corrective action candidates. Along with considering cost and benefit of competing corrective actions, we also incorporate the risk and robustness of corrective actions. An example is provided to represent the applicability of the proposed model.

  7. Photon number amplification/duplication through parametric conversion

    NASA Technical Reports Server (NTRS)

    Dariano, G. M.; Macchiavello, C.; Paris, M.

    1993-01-01

    The performance of parametric conversion in achieving number amplification and duplication is analyzed. It is shown that the effective maximum gains G(sub *) remain well below their integer ideal values, even for large signals. Correspondingly, one has output Fano factors F(sub *) which are increasing functions of the input photon number. On the other hand, in the inverse (deamplifier/recombiner) operating mode quasi-ideal gains G(sub *) and small factors F(sub *) approximately equal to 10 percent are obtained. Output noise and non-ideal gains are ascribed to spontaneous parametric emission.

  8. Parametrically excited helicopter ground resonance dynamics with high blade asymmetries

    NASA Astrophysics Data System (ADS)

    Sanches, L.; Michon, G.; Berlioz, A.; Alazard, D.

    2012-07-01

    The present work is aimed at verifying the influence of high asymmetries in the variation of in-plane lead-lag stiffness of one blade on the ground resonance phenomenon in helicopters. The periodical equations of motions are analyzed by using Floquet's Theory (FM) and the boundaries of instabilities predicted. The stability chart obtained as a function of asymmetry parameters and rotor speed reveals a complex evolution of critical zones and the existence of bifurcation points at low rotor speed values. Additionally, it is known that when treated as parametric excitations; periodic terms may cause parametric resonances in dynamic systems, some of which can become unstable. Therefore, the helicopter is later considered as a parametrically excited system and the equations are treated analytically by applying the Method of Multiple Scales (MMS). A stability analysis is used to verify the existence of unstable parametric resonances with first and second-order sets of equations. The results are compared and validated with those obtained by Floquet's Theory. Moreover, an explanation is given for the presence of unstable motion at low rotor speeds due to parametric instabilities of the second order.

  9. Autonomy and Firefighting: Perceived Competence and Stress.

    PubMed

    Chiang, Evelyn S; Baley, John; Ponder, Joy; Padilla, Miguel A

    2016-12-01

    In workplace settings, autonomy is implicated in employee motivation as well as supervisor autonomy support. As a profession of risk, firefighters may experience greater levels of stress. A self-determination paradigm was applied to the firefighter workplace. Of particular interest were perceived competence (to perform job duties) and the experience of stress. Firefighters' levels of autonomous and controlled regulation were surveyed, along with their perceptions of the autonomy support of their immediate supervisor. Autonomous regulation was positively related to perceived competence, whereas controlled regulation was negatively related. Higher levels of controlled regulation were also connected with greater stress. In contrast, greater perceived autonomy support was associated with decreased stress. Both perceived competence and stress are related to firefighter motivation and autonomy support. Recommendations are offered to increase autonomy support by chief officers.

  10. Parametric modelling of cost data in medical studies.

    PubMed

    Nixon, R M; Thompson, S G

    2004-04-30

    The cost of medical resources used is often recorded for each patient in clinical studies in order to inform decision-making. Although cost data are generally skewed to the right, interest is in making inferences about the population mean cost. Common methods for non-normal data, such as data transformation, assuming asymptotic normality of the sample mean or non-parametric bootstrapping, are not ideal. This paper describes possible parametric models for analysing cost data. Four example data sets are considered, which have different sample sizes and degrees of skewness. Normal, gamma, log-normal, and log-logistic distributions are fitted, together with three-parameter versions of the latter three distributions. Maximum likelihood estimates of the population mean are found; confidence intervals are derived by a parametric BC(a) bootstrap and checked by MCMC methods. Differences between model fits and inferences are explored.Skewed parametric distributions fit cost data better than the normal distribution, and should in principle be preferred for estimating the population mean cost. However for some data sets, we find that models that fit badly can give similar inferences to those that fit well. Conversely, particularly when sample sizes are not large, different parametric models that fit the data equally well can lead to substantially different inferences. We conclude that inferences are sensitive to choice of statistical model, which itself can remain uncertain unless there is enough data to model the tail of the distribution accurately. Investigating the sensitivity of conclusions to choice of model should thus be an essential component of analysing cost data in practice. Copyright 2004 John Wiley & Sons, Ltd.

  11. First-Order Parametric Model of Reflectance Spectra for Dyed Fabrics

    DTIC Science & Technology

    2016-02-19

    Unclassified Unlimited 31 Daniel Aiken (202) 279-5293 Parametric modeling Inverse /direct analysis This report describes a first-order parametric model of...Appendix: Dielectric Response Functions for Dyes Obtained by Inverse Analysis ……………………………...…………………………………………………….19 1 First-Order Parametric...which provides for both their inverse and direct modeling1. The dyes considered contain spectral features that are of interest to the U.S. Navy for

  12. Ghost imaging via optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Li, Hong-Guo; Zhang, De-Jian; Xu, De-Qin; Zhao, Qiu-Li; Wang, Sen; Wang, Hai-Bo; Xiong, Jun; Wang, Kaige

    2015-10-01

    We investigate theoretically and experimentally thermal light ghost imaging where the light transmitted through the object as the seed light is amplified by an optical parametric amplifier (OPA). In conventional lens imaging systems with OPA, the spectral bandwidth of OPA dominates the image resolution. Theoretically, we prove that in ghost imaging via optical parametric amplification (GIOPA) the bandwidth of OPA will not affect the image resolution. The experimental results show that for weak seed light the image quality in GIOPA is better than that of conventional ghost imaging. Our work may be valuable in remote sensing with ghost imaging technique, where the light passed through the object is weak after a long-distance propagation.

  13. New graph polynomials in parametric QED Feynman integrals

    NASA Astrophysics Data System (ADS)

    Golz, Marcel

    2017-10-01

    In recent years enormous progress has been made in perturbative quantum field theory by applying methods of algebraic geometry to parametric Feynman integrals for scalar theories. The transition to gauge theories is complicated not only by the fact that their parametric integrand is much larger and more involved. It is, moreover, only implicitly given as the result of certain differential operators applied to the scalar integrand exp(-ΦΓ /ΨΓ) , where ΨΓ and ΦΓ are the Kirchhoff and Symanzik polynomials of the Feynman graph Γ. In the case of quantum electrodynamics we find that the full parametric integrand inherits a rich combinatorial structure from ΨΓ and ΦΓ. In the end, it can be expressed explicitly as a sum over products of new types of graph polynomials which have a combinatoric interpretation via simple cycle subgraphs of Γ.

  14. Parametrically driven scalar field in an expanding background

    NASA Astrophysics Data System (ADS)

    Yanez-Pagans, Sergio; Urzagasti, Deterlino; Oporto, Zui

    2017-10-01

    We study the existence and dynamic behavior of localized and extended structures in a massive scalar inflaton field ϕ in 1 +1 dimensions in the framework of an expanding universe with constant Hubble parameter. We introduce a parametric forcing, produced by another quantum scalar field ψ , over the effective mass squared around the minimum of the inflaton potential. For this purpose, we study the system in the context of the cubic quintic complex Ginzburg-Landau equation and find the associated amplitude equation to the cosmological scalar field equation, which near the parametric resonance allows us to find the field amplitude. We find homogeneous null solutions, flat-top expanding solitons, and dark soliton patterns. No persistent non-null solutions are found in the absence of parametric forcing, and divergent solutions are obtained when the forcing amplitude is greater than 4 /3 .

  15. Stock price forecasting for companies listed on Tehran stock exchange using multivariate adaptive regression splines model and semi-parametric splines technique

    NASA Astrophysics Data System (ADS)

    Rounaghi, Mohammad Mahdi; Abbaszadeh, Mohammad Reza; Arashi, Mohammad

    2015-11-01

    One of the most important topics of interest to investors is stock price changes. Investors whose goals are long term are sensitive to stock price and its changes and react to them. In this regard, we used multivariate adaptive regression splines (MARS) model and semi-parametric splines technique for predicting stock price in this study. The MARS model as a nonparametric method is an adaptive method for regression and it fits for problems with high dimensions and several variables. semi-parametric splines technique was used in this study. Smoothing splines is a nonparametric regression method. In this study, we used 40 variables (30 accounting variables and 10 economic variables) for predicting stock price using the MARS model and using semi-parametric splines technique. After investigating the models, we select 4 accounting variables (book value per share, predicted earnings per share, P/E ratio and risk) as influencing variables on predicting stock price using the MARS model. After fitting the semi-parametric splines technique, only 4 accounting variables (dividends, net EPS, EPS Forecast and P/E Ratio) were selected as variables effective in forecasting stock prices.

  16. A unified framework for weighted parametric multiple test procedures.

    PubMed

    Xi, Dong; Glimm, Ekkehard; Maurer, Willi; Bretz, Frank

    2017-09-01

    We describe a general framework for weighted parametric multiple test procedures based on the closure principle. We utilize general weighting strategies that can reflect complex study objectives and include many procedures in the literature as special cases. The proposed weighted parametric tests bridge the gap between rejection rules using either adjusted significance levels or adjusted p-values. This connection is made by allowing intersection hypotheses of the underlying closed test procedure to be tested at level smaller than α. This may be also necessary to take certain study situations into account. For such cases we introduce a subclass of exact α-level parametric tests that satisfy the consonance property. When the correlation is known only for certain subsets of the test statistics, a new procedure is proposed to fully utilize this knowledge within each subset. We illustrate the proposed weighted parametric tests using a clinical trial example and conduct a simulation study to investigate its operating characteristics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Fitting C 2 Continuous Parametric Surfaces to Frontiers Delimiting Physiologic Structures

    PubMed Central

    Bayer, Jason D.

    2014-01-01

    We present a technique to fit C 2 continuous parametric surfaces to scattered geometric data points forming frontiers delimiting physiologic structures in segmented images. Such mathematical representation is interesting because it facilitates a large number of operations in modeling. While the fitting of C 2 continuous parametric curves to scattered geometric data points is quite trivial, the fitting of C 2 continuous parametric surfaces is not. The difficulty comes from the fact that each scattered data point should be assigned a unique parametric coordinate, and the fit is quite sensitive to their distribution on the parametric plane. We present a new approach where a polygonal (quadrilateral or triangular) surface is extracted from the segmented image. This surface is subsequently projected onto a parametric plane in a manner to ensure a one-to-one mapping. The resulting polygonal mesh is then regularized for area and edge length. Finally, from this point, surface fitting is relatively trivial. The novelty of our approach lies in the regularization of the polygonal mesh. Process performance is assessed with the reconstruction of a geometric model of mouse heart ventricles from a computerized tomography scan. Our results show an excellent reproduction of the geometric data with surfaces that are C 2 continuous. PMID:24782911

  18. Assessing engineering students' demonstration of workplace competencies in experiential learning environments through internships and cooperative work experiences

    NASA Astrophysics Data System (ADS)

    Laingen, Mark A.

    This study investigates the relationships between supervisor assessments and internship students' self-assessments for 15 workplace competencies, demonstrated in an internship or cooperative work environment. The 15 workplace competencies were developed by Iowa State University in collaboration with over 200 constituents comprised of Iowa State University COE alumni, engineering employers, COE faculty, partnering international faculty, and COE students, to provide clear, independent, and assessable measures for the eleven learning outcomes identified in the ABET Criterion 3 (a-k) outcomes. The study investigated workplace competency assessment data collected over ten years, commencing with the fall 2001 internship assessment term and concluding with the fall 2011 assessment term. The study used three separate methodologies to analyze workplace competency assessments in the COE. Part 1 analyzed data across the fifteen workplace competencies, and across ten programs in the College of Engineering, that have been involved with the workplace competency assessment of internship and cooperative students from the beginning of data collection in 2001. Supervisor assessment ratings were compared to internship student self-assessment ratings across the ten-year span from 2001-11using the non-parametric equivalent of the paired t-test; the Wilcoxon singed rank test for paired data. Part 2 of the study investigated the relationship between supervisor and student self-assessment data across assessment terms related to the 2001-05 and 2006-11 ABET accreditation cycles. The third part investigated how data tracking workplace competency strengths and weaknesses and ABET outcomes achievement percentages have changed between the assessment terms across accreditation cycles. Part 3 included an on-line survey sent to program curriculum committee members involved with workplace competency assessment data that investigated how the engineering programs are utilizing this data in support

  19. Free response approach in a parametric system

    NASA Astrophysics Data System (ADS)

    Huang, Dishan; Zhang, Yueyue; Shao, Hexi

    2017-07-01

    In this study, a new approach to predict the free response in a parametric system is investigated. It is proposed in the special form of a trigonometric series with an exponentially decaying function of time, based on the concept of frequency splitting. By applying harmonic balance, the parametric vibration equation is transformed into an infinite set of homogeneous linear equations, from which the principal oscillation frequency can be computed, and all coefficients of harmonic components can be obtained. With initial conditions, arbitrary constants in a general solution can be determined. To analyze the computational accuracy and consistency, an approach error function is defined, which is used to assess the computational error in the proposed approach and in the standard numerical approach based on the Runge-Kutta algorithm. Furthermore, an example of a dynamic model of airplane wing flutter on a turbine engine is given to illustrate the applicability of the proposed approach. Numerical solutions show that the proposed approach exhibits high accuracy in mathematical expression, and it is valuable for theoretical research and engineering applications of parametric systems.

  20. 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

  1. SCHIP premiums, enrollment, and expenditures: a two state, competing risk analysis.

    PubMed

    Marton, James; Ketsche, Patricia G; Zhou, Mei

    2010-07-01

    Faced with state budget troubles, policymakers may introduce or increase State Children's Health Insurance Program (SCHIP) premiums for children in the highest program income eligibility categories. In this paper we compare the responses of SCHIP recipients in a state (Kentucky) that introduced SCHIP premiums for the first time at the end of 2003 with the responses of recipients in a state (Georgia) that increased existing SCHIP premiums in mid-2004. We start with a theoretical examination of how these different policies create different changes to family budget constraints and produce somewhat different financial incentives for recipients. Next we empirically model the impact of these policies using a competing risk approach to differentiate exits due to transfers to other eligibility categories of public coverage from exiting the public health insurance system. In both states we find a short-run increase in the likelihood that children transfer to lower- income eligibility/lower-premium categories of SCHIP. We also find a short-run increase in the rate at which children transfer from SCHIP to Medicaid in Kentucky, which is consistent with our theoretical model. These findings have important financial implications for state budgets, as the matching rates and premium levels are different for different eligibility categories of public coverage. Copyright (c) 2009 John Wiley & Sons, Ltd.

  2. Comparison of parametric and bootstrap method in bioequivalence test.

    PubMed

    Ahn, Byung-Jin; Yim, Dong-Seok

    2009-10-01

    The estimation of 90% parametric confidence intervals (CIs) of mean AUC and Cmax ratios in bioequivalence (BE) tests are based upon the assumption that formulation effects in log-transformed data are normally distributed. To compare the parametric CIs with those obtained from nonparametric methods we performed repeated estimation of bootstrap-resampled datasets. The AUC and Cmax values from 3 archived datasets were used. BE tests on 1,000 resampled datasets from each archived dataset were performed using SAS (Enterprise Guide Ver.3). Bootstrap nonparametric 90% CIs of formulation effects were then compared with the parametric 90% CIs of the original datasets. The 90% CIs of formulation effects estimated from the 3 archived datasets were slightly different from nonparametric 90% CIs obtained from BE tests on resampled datasets. Histograms and density curves of formulation effects obtained from resampled datasets were similar to those of normal distribution. However, in 2 of 3 resampled log (AUC) datasets, the estimates of formulation effects did not follow the Gaussian distribution. Bias-corrected and accelerated (BCa) CIs, one of the nonparametric CIs of formulation effects, shifted outside the parametric 90% CIs of the archived datasets in these 2 non-normally distributed resampled log (AUC) datasets. Currently, the 80~125% rule based upon the parametric 90% CIs is widely accepted under the assumption of normally distributed formulation effects in log-transformed data. However, nonparametric CIs may be a better choice when data do not follow this assumption.

  3. Comparison of Parametric and Bootstrap Method in Bioequivalence Test

    PubMed Central

    Ahn, Byung-Jin

    2009-01-01

    The estimation of 90% parametric confidence intervals (CIs) of mean AUC and Cmax ratios in bioequivalence (BE) tests are based upon the assumption that formulation effects in log-transformed data are normally distributed. To compare the parametric CIs with those obtained from nonparametric methods we performed repeated estimation of bootstrap-resampled datasets. The AUC and Cmax values from 3 archived datasets were used. BE tests on 1,000 resampled datasets from each archived dataset were performed using SAS (Enterprise Guide Ver.3). Bootstrap nonparametric 90% CIs of formulation effects were then compared with the parametric 90% CIs of the original datasets. The 90% CIs of formulation effects estimated from the 3 archived datasets were slightly different from nonparametric 90% CIs obtained from BE tests on resampled datasets. Histograms and density curves of formulation effects obtained from resampled datasets were similar to those of normal distribution. However, in 2 of 3 resampled log (AUC) datasets, the estimates of formulation effects did not follow the Gaussian distribution. Bias-corrected and accelerated (BCa) CIs, one of the nonparametric CIs of formulation effects, shifted outside the parametric 90% CIs of the archived datasets in these 2 non-normally distributed resampled log (AUC) datasets. Currently, the 80~125% rule based upon the parametric 90% CIs is widely accepted under the assumption of normally distributed formulation effects in log-transformed data. However, nonparametric CIs may be a better choice when data do not follow this assumption. PMID:19915699

  4. Metroticket 2.0 Model for Analysis of Competing Risks of Death After Liver Transplantation for Hepatocellular Carcinoma.

    PubMed

    Mazzaferro, Vincenzo; Sposito, Carlo; Zhou, Jian; Pinna, Antonio D; De Carlis, Luciano; Fan, Jia; Cescon, Matteo; Di Sandro, Stefano; Yi-Feng, He; Lauterio, Andrea; Bongini, Marco; Cucchetti, Alessandro

    2018-01-01

    Outcomes of liver transplantation for hepatocellular carcinoma (HCC) are determined by cancer-related and non-related events. Treatments for hepatitis C virus infection have reduced non-cancer events among patients receiving liver transplants, so reducing HCC-related death might be an actionable end point. We performed a competing-risk analysis to evaluate factors associated with survival of patients with HCC and developed a prognostic model based on features of HCC patients before liver transplantation. We performed multivariable competing-risk regression analysis to identify factors associated with HCC-specific death of patients who underwent liver transplantation. The training set comprised 1018 patients who underwent liver transplantation for HCC from January 2000 through December 2013 at 3 tertiary centers in Italy. The validation set comprised 341 consecutive patients who underwent liver transplantation for HCC during the same period at the Liver Cancer Institute in Shanghai, China. We collected pretransplantation data on etiology of liver disease, number and size of tumors, patient level of α-fetoprotein (AFP), model for end-stage liver disease score, tumor stage, numbers and types of treatment, response to treatments, tumor grade, microvascular invasion, dates, and causes of death. Death was defined as HCC-specific when related to HCC recurrence after transplantation, disseminated extra- and/or intrahepatic tumor relapse and worsened liver function in presence of tumor spread. The cumulative incidence of death was segregated for hepatitis C virus status. In the competing-risk regression, the sum of tumor number and size and of log 10 level of AFP were significantly associated with HCC-specific death (P < .001), returning an average c-statistic of 0.780 (95% confidence interval, 0.763-0.798). Five-year cumulative incidence of non-HCC-related death was 8.6% in HCV-negative patients and 18.1% in HCV-positive patients. For patients with HCC to have a 70

  5. 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

  6. Parametrization study of the land multiparameter VTI elastic waveform inversion

    NASA Astrophysics Data System (ADS)

    He, W.; Plessix, R.-É.; Singh, S.

    2018-06-01

    Multiparameter inversion of seismic data remains challenging due to the trade-off between the different elastic parameters and the non-uniqueness of the solution. The sensitivity of the seismic data to a given subsurface elastic parameter depends on the source and receiver ray/wave path orientations at the subsurface point. In a high-frequency approximation, this is commonly analysed through the study of the radiation patterns that indicate the sensitivity of each parameter versus the incoming (from the source) and outgoing (to the receiver) angles. In practice, this means that the inversion result becomes sensitive to the choice of parametrization, notably because the null-space of the inversion depends on this choice. We can use a least-overlapping parametrization that minimizes the overlaps between the radiation patterns, in this case each parameter is only sensitive in a restricted angle domain, or an overlapping parametrization that contains a parameter sensitive to all angles, in this case overlaps between the radiation parameters occur. Considering a multiparameter inversion in an elastic vertically transverse isotropic medium and a complex land geological setting, we show that the inversion with the least-overlapping parametrization gives less satisfactory results than with the overlapping parametrization. The difficulties come from the complex wave paths that make difficult to predict the areas of sensitivity of each parameter. This shows that the parametrization choice should not only be based on the radiation pattern analysis but also on the angular coverage at each subsurface point that depends on geology and the acquisition layout.

  7. Aircraft conceptual design - an adaptable parametric sizing methodology

    NASA Astrophysics Data System (ADS)

    Coleman, Gary John, Jr.

    Aerospace is a maturing industry with successful and refined baselines which work well for traditional baseline missions, markets and technologies. However, when new markets (space tourism) or new constrains (environmental) or new technologies (composite, natural laminar flow) emerge, the conventional solution is not necessarily best for the new situation. Which begs the question "how does a design team quickly screen and compare novel solutions to conventional solutions for new aerospace challenges?" The answer is rapid and flexible conceptual design Parametric Sizing. In the product design life-cycle, parametric sizing is the first step in screening the total vehicle in terms of mission, configuration and technology to quickly assess first order design and mission sensitivities. During this phase, various missions and technologies are assessed. During this phase, the designer is identifying design solutions of concepts and configurations to meet combinations of mission and technology. This research undertaking contributes the state-of-the-art in aircraft parametric sizing through (1) development of a dedicated conceptual design process and disciplinary methods library, (2) development of a novel and robust parametric sizing process based on 'best-practice' approaches found in the process and disciplinary methods library, and (3) application of the parametric sizing process to a variety of design missions (transonic, supersonic and hypersonic transports), different configurations (tail-aft, blended wing body, strut-braced wing, hypersonic blended bodies, etc.), and different technologies (composite, natural laminar flow, thrust vectored control, etc.), in order to demonstrate the robustness of the methodology and unearth first-order design sensitivities to current and future aerospace design problems. This research undertaking demonstrates the importance of this early design step in selecting the correct combination of mission, technologies and configuration to

  8. Oncology Nurse Generalist Competencies: Oncology Nursing Society’s Initiative to Establish Best Practice

    PubMed

    Gaguski, Michele; George, Kim; Bruce, Susan; Brucker, Edie; Leija, Carol; LeFebvre, Kristine; Thompson Mackey, Heather

    2017-09-25

    A project team was formulated by the Oncology Nursing Society (ONS) to create evidence-based oncology nurse generalist (ONG) competencies to establish best practices in competency development, including high-risk tasks, critical thinking criteria, and measurement of key areas for oncology nurses. This article aims to describe the process and the development of ONG competencies. This article describes how the ONG competencies were accomplished, and includes outcomes and suggestions for use in clinical practice. Institutions can use the ONG competencies to assess and develop competency programs, offer unique educational strategies to measure and appraise proficiency, and establish processes to foster a workplace environment committed to mentoring and teaching future oncology nurses. 2017 Oncology Nursing Society

  9. The parametric resonance—from LEGO Mindstorms to cold atoms

    NASA Astrophysics Data System (ADS)

    Kawalec, Tomasz; Sierant, Aleksandra

    2017-07-01

    We show an experimental setup based on a popular LEGO Mindstorms set, allowing us to both observe and investigate the parametric resonance phenomenon. The presented method is simple but covers a variety of student activities like embedded software development, conducting measurements, data collection and analysis. It may be used during science shows, as part of student projects and to illustrate the parametric resonance in mechanics or even quantum physics, during lectures or classes. The parametrically driven LEGO pendulum gains energy in a spectacular way, increasing its amplitude from 10° to about 100° within a few tens of seconds. We provide also a short description of a wireless absolute orientation sensor that may be used in quantitative analysis of driven or free pendulum movement.

  10. 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.

  11. Free-form geometric modeling by integrating parametric and implicit PDEs.

    PubMed

    Du, Haixia; Qin, Hong

    2007-01-01

    Parametric PDE techniques, which use partial differential equations (PDEs) defined over a 2D or 3D parametric domain to model graphical objects and processes, can unify geometric attributes and functional constraints of the models. PDEs can also model implicit shapes defined by level sets of scalar intensity fields. In this paper, we present an approach that integrates parametric and implicit trivariate PDEs to define geometric solid models containing both geometric information and intensity distribution subject to flexible boundary conditions. The integrated formulation of second-order or fourth-order elliptic PDEs permits designers to manipulate PDE objects of complex geometry and/or arbitrary topology through direct sculpting and free-form modeling. We developed a PDE-based geometric modeling system for shape design and manipulation of PDE objects. The integration of implicit PDEs with parametric geometry offers more general and arbitrary shape blending and free-form modeling for objects with intensity attributes than pure geometric models.

  12. Do we need a threshold conception of competence?

    PubMed

    den Hartogh, Govert

    2016-03-01

    On the standard view we assess a person's competence by considering her relevant abilities without reference to the actual decision she is about to make. If she is deemed to satisfy certain threshold conditions of competence, it is still an open question whether her decision could ever be overruled on account of its harmful consequences for her ('hard paternalism'). In practice, however, one normally uses a variable, risk dependent conception of competence, which really means that in considering whether or not to respect a person's decision-making authority we weigh her decision on several relevant dimensions at the same time: its harmful consequences, its importance in terms of the person's own relevant values, the infringement of her autonomy involved in overruling it, and her decision-making abilities. I argue that we should openly recognize the multi-dimensional nature of this judgment. This implies rejecting both the threshold conception of competence and the categorical distinction between hard and soft paternalism.

  13. Parametric-Studies and Data-Plotting Modules for the SOAP

    NASA Technical Reports Server (NTRS)

    2008-01-01

    "Parametric Studies" and "Data Table Plot View" are the names of software modules in the Satellite Orbit Analysis Program (SOAP). Parametric Studies enables parameterization of as many as three satellite or ground-station attributes across a range of values and computes the average, minimum, and maximum of a specified metric, the revisit time, or 21 other functions at each point in the parameter space. This computation produces a one-, two-, or three-dimensional table of data representing statistical results across the parameter space. Inasmuch as the output of a parametric study in three dimensions can be a very large data set, visualization is a paramount means of discovering trends in the data (see figure). Data Table Plot View enables visualization of the data table created by Parametric Studies or by another data source: this module quickly generates a display of the data in the form of a rotatable three-dimensional-appearing plot, making it unnecessary to load the SOAP output data into a separate plotting program. The rotatable three-dimensionalappearing plot makes it easy to determine which points in the parameter space are most desirable. Both modules provide intuitive user interfaces for ease of use.

  14. Parametric Equations: Push 'Em Back, Push 'Em Back, Way Back!

    ERIC Educational Resources Information Center

    Cieply, Joseph F.

    1993-01-01

    Stresses using the features of graphing calculators to teach parametric equations much earlier in the curriculum than is presently done. Examples using parametric equations to teach slopes and lines in beginning algebra, inverse functions in advanced algebra, the wrapping function, and simulations of physical phenomena are presented. (MAZ)

  15. Competency courts: a creative solution for restoring competency to the competency process.

    PubMed

    Finkle, Michael J; Kurth, Russell; Cadle, Christopher; Mullan, Jessica

    2009-01-01

    It is well accepted that jail is a poor setting for treating the acutely mentally ill, yet the number of mentally ill persons in jail has increased such that Los Angeles County Jail and Riker's Island in New York house more mentally ill than any psychiatric hospital. The number of mentally ill persons charged with a crime whose competency to stand trial is in question has also increased dramatically. Inefficiencies within the competency process result in mentally ill persons charged with crimes remaining in jail longer than necessary. One solution is "competency court", a specialty court within a mental health court. The same judges, attorneys, and mental health professionals staff both courts. By combining their Mental Health Court experience, they can work with the mentally ill using their expertise in competency law and processes, and thereby improve the competency process and reduce the unnecessary time that mentally ill persons spend in jail. (c) 2009 John Wiley & Sons, Ltd.

  16. Parametric Architecture in the Urban Space

    NASA Astrophysics Data System (ADS)

    Januszkiewicz, Krystyna; Kowalski, Karol G.

    2017-10-01

    The paper deals with the parametric architecture which is trying to introduce a new spatial language in the context for urban tissue that correspond to the artistic consciousness and the attitude of information and digital technologies era. The first part of the paper defines the main features of parametric architecture (such as: folding, continuity and curvilinearity) which are are characteristic of the new style of named the “parametricism”. This architecture is a strong emphasis on geometry, materiality, feasibility and sustainability, what emerges is an explicit agenda promoting material ornamentation, spatial spectacle and formal theatricality. The second part presents result of case study, especially parametric public use buildings, within the tissue of city. The analyzed objects are: The Sage Gateshead (1998-2004) in Gateshead, Kunsthaus in Graz (2000-2003), the Weltstadthaus (2003-2005) in Cologne, The Golden Terraces in Warsaw (2000-2007), the Metropol Parasol in Seville (2005-2011) the King Cross Station (2005-2012) in London, the headquarters of the Pathé Foundation (2006-2014) in Paris. Each of the enumerated examples shows a diverse approach to designing in the urban space, which reflect the age of digital technologies and the information society. In conclusion emphasizes, that new concept of the spatialization of architecture is the equivalent of the democratization of the political system, the liberalization of the economy, among other examples.

  17. Josephson parametric converter saturation and higher order effects

    NASA Astrophysics Data System (ADS)

    Liu, G.; Chien, T.-C.; Cao, X.; Lanes, O.; Alpern, E.; Pekker, D.; Hatridge, M.

    2017-11-01

    Microwave parametric amplifiers based on Josephson junctions have become indispensable components of many quantum information experiments. One key limitation which has not been well predicted by theory is the gain saturation behavior which limits the amplifier's ability to process large amplitude signals. The typical explanation for this behavior in phase-preserving amplifiers based on three-wave mixing, such as the Josephson Parametric Converter, is pump depletion, in which the consumption of pump photons to produce amplification results in a reduction in gain. However, in this work, we present experimental data and theoretical calculations showing that the fourth-order Kerr nonlinearities inherent in Josephson junctions are the dominant factor. The Kerr-based theory has the unusual property of causing saturation to both lower and higher gains, depending on bias conditions. This work presents an efficient methodology for optimizing device performance in the presence of Kerr nonlinearities while retaining device tunability and points to the necessity of controlling higher-order Hamiltonian terms to make further improvements in parametric devices.

  18. Epicyclic helical channels for parametric resonance ionization cooling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Johson, Rolland Paul; Derbenev, Yaroslav

    Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parametermore » range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.« less

  19. Competing-risks mortality after radiotherapy vs. observation for localized prostate cancer: a population-based study.

    PubMed

    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

    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. 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. 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). 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. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Ethical media competence as a protective factor against cyberbullying and cybervictimization among german school students.

    PubMed

    Müller, Christin R; Pfetsch, Jan; Ittel, Angela

    2014-10-01

    The use of digital information and communication technologies is an integral part of adolescents' everyday life. Besides various opportunities for information, entertainment, and communication, media use is associated with risks such as cyberbullying. Cyberbullying refers to aggressive behavior in the context of computer-mediated communication, characterized by repetition, an intention to harm, and power imbalance. Previous studies have shown that increased media use is a major risk factor for cyberbullying and cybervictimization. Given that restricting media use is not a practical way to reduce the negative effects inherent in media use, the present study examines the relevance of ethical media competence. We expected ethical media competence to buffer the effect of increased media use on cyberbullying and cybervictimization. A survey was conducted with 934 students (53% female) aged 10-17 years (M=13.26, SD=1.63). As expected, hierarchical regression analyses showed a positive main effect of media use, a negative main effect of ethical media competence, and a negative interaction effect of media use and media competence on cyberbullying and cybervictimization. Simple slope analyses revealed that at high levels of ethical media competence, media use has almost no effect on cybervictimization and a significant negative effect on cyberbullying. Consequently, promoting ethical media competence constitutes a potential measure to prevent the risks of increased media use for cyberbullying and cybervictimization.

  1. Harmonic generation and parametric decay in the ion cyclotron frequency range

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Skiff, F.N.; Wong, K.L.; Ono, M.

    1984-06-01

    Harmonic generation and parametric decay are examined in a toroidal ACT-I plasma using electrostatic plate antennas. The harmonic generation, which is consistent with sheath rectification, is sufficiently strong that the nonlinearly generated harmonic modes themselves decay parametrically. Resonant and nonresonant parametric decay of the second harmonic are observed and compared with uniform pump theory. Resonant decay of lower hybrid waves into lower hybrid waves and slow ion cyclotron waves is seen for the first time. Surprisingly, the decay processes are nonlinearly saturated, indicating absolute instability.

  2. Gated frequency-resolved optical imaging with an optical parametric amplifier

    DOEpatents

    Cameron, Stewart M.; Bliss, David E.; Kimmel, Mark W.; Neal, Daniel R.

    1999-01-01

    A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media.

  3. Circulation and Directional Amplification in the Josephson Parametric Converter

    NASA Astrophysics Data System (ADS)

    Hatridge, Michael

    Nonreciprocal transport and directional amplification of weak microwave signals are fundamental ingredients in performing efficient measurements of quantum states of flying microwave light. This challenge has been partly met, as quantum-limited amplification is now regularly achieved with parametrically-driven, Josephson-junction based superconducting circuits. However, these devices are typically non-directional, requiring external circulators to separate incoming and outgoing signals. Recently this limitation has been overcome by several proposals and experimental realizations of both directional amplifiers and circulators based on interference between several parametric processes in a single device. This new class of multi-parametrically driven devices holds the promise of achieving a variety of desirable characteristics simultaneously- directionality, reduced gain-bandwidth constraints and quantum-limited added noise, and are good candidates for on-chip integration with other superconducting circuits such as qubits.

  4. Promoting culturally competent care for gay youth.

    PubMed

    Bakker, Leslie J; Cavender, Angela

    2003-04-01

    Gay youth and those questioning their sexual identity have been referred to as "hidden," "invisible," "stigmatized," and "marginalized." As a result, the unique safety and health needs of this subculture have been overlooked, or worse, ignored, placing these youth at risk. Because school nurses have been identifying at-risk populations of students and developing programs to promote youth and family health for years, they should be prepared to provide health care for the subculture of gay youth. However, nurses are saying they do not have the knowledge or skills needed to identify and address the needs of this group. Providing school nursing care for gay youth requires the school nurse to be culturally competent. School nurses need to be aware of, sensitive to, and knowledgeable about the subculture. They must also possess communication skills required to relate appropriately to this group. This article presents information and nursing strategies that will promote the safety and health of gay youth while enhancing the school nurse's cultural competence.

  5. Parametric models of reflectance spectra for dyed fabrics

    NASA Astrophysics Data System (ADS)

    Aiken, Daniel C.; Ramsey, Scott; Mayo, Troy; Lambrakos, Samuel G.; Peak, Joseph

    2016-05-01

    This study examines parametric modeling of NIR reflectivity spectra for dyed fabrics, which provides for both their inverse and direct modeling. The dye considered for prototype analysis is triarylamine dye. The fabrics considered are camouflage textiles characterized by color variations. The results of this study provide validation of the constructed parametric models, within reasonable error tolerances for practical applications, including NIR spectral characteristics in camouflage textiles, for purposes of simulating NIR spectra corresponding to various dye concentrations in host fabrics, and potentially to mixtures of dyes.

  6. Dispersion-Engineered Traveling Wave Kinetic Inductance Parametric Amplifier

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, Jonas (Inventor); Day, Peter K. (Inventor)

    2014-01-01

    A traveling wave kinetic inductance parametric amplifier comprises a superconducting transmission line and a dispersion control element. The transmission line can include periodic variations of its dimension along its length. The superconducting material can include a high normal state resistivity material. In some instances the high normal state resistivity material includes nitrogen and a metal selected from the group consisting of titanium, niobium and vanadium. The traveling wave kinetic inductance parametric amplifier is expected to exhibit a noise temperature below 100 mK/GHz.

  7. On assessing surrogacy in a single trial setting using a semi-competing risks paradigm

    PubMed Central

    Ghosh, Debashis

    2009-01-01

    Summary There has been a recent emphasis on the identification of biomarkers and other biologic measures that may be potentially used as surrogate endpoints in clinical trials. We focus on the setting of data from a single clinical trial. In this paper, we consider a framework in which the surrogate must occur before the true endpoint. This suggests viewing the surrogate and true endpoints as semi-competing risks data; this approach is new to the literature on surrogate endpoints and leads to an asymmetrical treatment of the surrogate and true endpoints. However, such a data structure also conceptually complicates many of the previously considered measures of surrogacy in the literature. We propose novel estimation and inferential procedures for the relative effect and adjusted association quantities proposed by Buyse and Molenberghs (1998, Biometrics, 1014 – 1029). The proposed methodology is illustrated with application to simulated data, as well as to data from a leukemia study. PMID:18759839

  8. Efficient model reduction of parametrized systems by matrix discrete empirical interpolation

    NASA Astrophysics Data System (ADS)

    Negri, Federico; Manzoni, Andrea; Amsallem, David

    2015-12-01

    In this work, we apply a Matrix version of the so-called Discrete Empirical Interpolation (MDEIM) for the efficient reduction of nonaffine parametrized systems arising from the discretization of linear partial differential equations. Dealing with affinely parametrized operators is crucial in order to enhance the online solution of reduced-order models (ROMs). However, in many cases such an affine decomposition is not readily available, and must be recovered through (often) intrusive procedures, such as the empirical interpolation method (EIM) and its discrete variant DEIM. In this paper we show that MDEIM represents a very efficient approach to deal with complex physical and geometrical parametrizations in a non-intrusive, efficient and purely algebraic way. We propose different strategies to combine MDEIM with a state approximation resulting either from a reduced basis greedy approach or Proper Orthogonal Decomposition. A posteriori error estimates accounting for the MDEIM error are also developed in the case of parametrized elliptic and parabolic equations. Finally, the capability of MDEIM to generate accurate and efficient ROMs is demonstrated on the solution of two computationally-intensive classes of problems occurring in engineering contexts, namely PDE-constrained shape optimization and parametrized coupled problems.

  9. Seven essential strategies for promoting and sustaining systemic cultural competence.

    PubMed

    Delphin-Rittmon, Miriam E; Andres-Hyman, Raquel; Flanagan, Elizabeth H; Davidson, Larry

    2013-03-01

    Racial and ethnic disparities are disturbing facets of the American healthcare system that document the reality of unequal treatment. Research consistently shows that patients of color experience poorer quality of care and health outcomes contributing to increased risks and accelerated mortality rates relative to their white counterparts. While initially conceptualized as an approach for increasing the responsiveness of children's behavioral health care, cultural competence has been adopted as a key strategy for eliminating racial and ethnic health disparities across the healthcare system. However, cultural competence research and practices largely focus on improving provider competencies, while agency and system level approaches for meeting the service needs of diverse populations are given less attention. In this article we offer seven essential strategies for promoting and sustaining organizational and systemic cultural competence. These strategies are to: (1) Provide executive level support and accountability, (2) Foster patient, community and stakeholder participation and partnerships, (3) Conduct organizational cultural competence assessments, (4) Develop incremental and realistic cultural competence action plans, (5) Ensure linguistic competence, (6) Diversify, develop, and retain a culturally competent workforce, and (7) Develop an agency or system strategy for managing staff and patient grievances. For each strategy we offer several recommendations for implementation.

  10. Gated frequency-resolved optical imaging with an optical parametric amplifier

    DOEpatents

    Cameron, S.M.; Bliss, D.E.; Kimmel, M.W.; Neal, D.R.

    1999-08-10

    A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media. 13 figs.

  11. Least Squares Approximation By G1 Piecewise Parametric Cubes

    DTIC Science & Technology

    1993-12-01

    ADDRESS(ES) 10.SPONSORING/MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES The views expressed in this thesis are those of the author and do not...CODE Approved for public release; distribution is unlimited. 13. ABSTRACT (maximum 200 words) Parametric piecewise cubic polynomials are used throughout...piecewise parametric cubic polynomial to a sequence of ordered points in the plane. Cubic Bdzier curves are used as a basis. The parameterization, the

  12. Sensitivity enhancement in swept-source optical coherence tomography by parametric balanced detector and amplifier

    PubMed Central

    Kang, Jiqiang; Wei, Xiaoming; Li, Bowen; Wang, Xie; Yu, Luoqin; Tan, Sisi; Jinata, Chandra; Wong, Kenneth K. Y.

    2016-01-01

    We proposed a sensitivity enhancement method of the interference-based signal detection approach and applied it on a swept-source optical coherence tomography (SS-OCT) system through all-fiber optical parametric amplifier (FOPA) and parametric balanced detector (BD). The parametric BD was realized by combining the signal and phase conjugated idler band that was newly-generated through FOPA, and specifically by superimposing these two bands at a photodetector. The sensitivity enhancement by FOPA and parametric BD in SS-OCT were demonstrated experimentally. The results show that SS-OCT with FOPA and SS-OCT with parametric BD can provide more than 9 dB and 12 dB sensitivity improvement, respectively, when compared with the conventional SS-OCT in a spectral bandwidth spanning over 76 nm. To further verify and elaborate their sensitivity enhancement, a bio-sample imaging experiment was conducted on loach eyes by conventional SS-OCT setup, SS-OCT with FOPA and parametric BD at different illumination power levels. All these results proved that using FOPA and parametric BD could improve the sensitivity significantly in SS-OCT systems. PMID:27446655

  13. Research on simplified parametric finite element model of automobile frontal crash

    NASA Astrophysics Data System (ADS)

    Wu, Linan; Zhang, Xin; Yang, Changhai

    2018-05-01

    The modeling method and key technologies of the automobile frontal crash simplified parametric finite element model is studied in this paper. By establishing the auto body topological structure, extracting and parameterizing the stiffness properties of substructures, choosing appropriate material models for substructures, the simplified parametric FE model of M6 car is built. The comparison of the results indicates that the simplified parametric FE model can accurately calculate the automobile crash responses and the deformation of the key substructures, and the simulation time is reduced from 6 hours to 2 minutes.

  14. Enhancing Key Competencies of Health Professionals in the Assessment and Care of Adults at Risk of Suicide Through Education and Technology.

    PubMed

    Ryan, Kathryn; Tindall, Claudia; Strudwick, Gillian

    This article describes efforts undertaken to improve the clinical competencies of health professionals in the area of suicide risk assessment, documentation, and care planning. Best practices that fit the mental health and addictions setting were identified from the Registered Nurses' Association of Ontario Best Practice Guideline on Assessment and Care of Adults at Risk for Suicidal Ideation and Behaviour. A variety of methods were used to implement the guidelines at the Centre for Addiction and Mental Health in Toronto, Ontario, Canada. These included 3 in-person educational modules, an e-learning module, and the creation of an electronic health record suicide risk assessment documentation form. Results showed that interprofessional team members improved their suicide awareness and increased their confidence and knowledge in suicide risk assessment and the identification of interventions for clients at risk. Organizational level performance and quality improvement activities after implementation of the education and the electronic suicide risk assessment documentation form are being implemented through a collaboration between performance improvement, clinical education and informatics, and professional practice. The success of an interprofessional educational program of this nature is dependent on the collaboration of a number of stakeholders from a variety of areas of the organization.

  15. A permutation-based non-parametric analysis of CRISPR screen data.

    PubMed

    Jia, Gaoxiang; Wang, Xinlei; Xiao, Guanghua

    2017-07-19

    Clustered regularly-interspaced short palindromic repeats (CRISPR) screens are usually implemented in cultured cells to identify genes with critical functions. Although several methods have been developed or adapted to analyze CRISPR screening data, no single specific algorithm has gained popularity. Thus, rigorous procedures are needed to overcome the shortcomings of existing algorithms. We developed a Permutation-Based Non-Parametric Analysis (PBNPA) algorithm, which computes p-values at the gene level by permuting sgRNA labels, and thus it avoids restrictive distributional assumptions. Although PBNPA is designed to analyze CRISPR data, it can also be applied to analyze genetic screens implemented with siRNAs or shRNAs and drug screens. We compared the performance of PBNPA with competing methods on simulated data as well as on real data. PBNPA outperformed recent methods designed for CRISPR screen analysis, as well as methods used for analyzing other functional genomics screens, in terms of Receiver Operating Characteristics (ROC) curves and False Discovery Rate (FDR) control for simulated data under various settings. Remarkably, the PBNPA algorithm showed better consistency and FDR control on published real data as well. PBNPA yields more consistent and reliable results than its competitors, especially when the data quality is low. R package of PBNPA is available at: https://cran.r-project.org/web/packages/PBNPA/ .

  16. Ultra-Broad-Band Optical Parametric Amplifier or Oscillator

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatolly; Maleki, Lute

    2009-01-01

    A concept for an ultra-broad-band optical parametric amplifier or oscillator has emerged as a by-product of a theoretical study in fundamental quantum optics. The study was originally intended to address the question of whether the two-photon temporal correlation function of light [in particular, light produced by spontaneous parametric down conversion (SPDC)] can be considerably narrower than the inverse of the spectral width (bandwidth) of the light. The answer to the question was found to be negative. More specifically, on the basis of the universal integral relations between the quantum two-photon temporal correlation and the classical spectrum of light, it was found that the lower limit of two-photon correlation time is set approximately by the inverse of the bandwidth. The mathematical solution for the minimum two-photon correlation time also provides the minimum relative frequency dispersion of the down-converted light components; in turn, the minimum relative frequency dispersion translates to the maximum bandwidth, which is important for the design of an ultra-broad-band optical parametric oscillator or amplifier. In the study, results of an analysis of the general integral relations were applied in the case of an optically nonlinear, frequency-dispersive crystal in which SPDC produces collinear photons. Equations were found for the crystal orientation and pump wavelength, specific for each parametric-down-converting crystal, that eliminate the relative frequency dispersion of collinear degenerate (equal-frequency) signal and idler components up to the fourth order in the frequency-detuning parameter

  17. Using competences and competence tools in workforce development.

    PubMed

    Green, Tess; Dickerson, Claire; Blass, Eddie

    The NHS Knowledge and Skills Framework (KSF) has been a driving force in the move to competence-based workforce development in the NHS. Skills for Health has developed national workforce competences that aim to improve behavioural performance, and in turn increase productivity. This article describes five projects established to test Skills for Health national workforce competences, electronic tools and products in different settings in the NHS. Competences and competence tools were used to redesign services, develop job roles, identify skills gaps and develop learning programmes. Reported benefits of the projects included increased clarity and a structured, consistent and standardized approach to workforce development. Findings from the evaluation of the tools were positive in terms of their overall usefulness and provision of related training/support. Reported constraints of using the competences and tools included issues relating to their availability, content and organization. It is recognized that a highly skilled and flexible workforce is important to the delivery of high-quality health care. These projects suggest that Skills for Health competences can be used as a 'common currency' in workforce development in the UK health sector. This would support the need to adapt rapidly to changing service needs.

  18. Small-window parametric imaging based on information entropy for ultrasound tissue characterization

    PubMed Central

    Tsui, Po-Hsiang; Chen, Chin-Kuo; Kuo, Wen-Hung; Chang, King-Jen; Fang, Jui; Ma, Hsiang-Yang; Chou, Dean

    2017-01-01

    Constructing ultrasound statistical parametric images by using a sliding window is a widely adopted strategy for characterizing tissues. Deficiency in spatial resolution, the appearance of boundary artifacts, and the prerequisite data distribution limit the practicability of statistical parametric imaging. In this study, small-window entropy parametric imaging was proposed to overcome the above problems. Simulations and measurements of phantoms were executed to acquire backscattered radiofrequency (RF) signals, which were processed to explore the feasibility of small-window entropy imaging in detecting scatterer properties. To validate the ability of entropy imaging in tissue characterization, measurements of benign and malignant breast tumors were conducted (n = 63) to compare performances of conventional statistical parametric (based on Nakagami distribution) and entropy imaging by the receiver operating characteristic (ROC) curve analysis. The simulation and phantom results revealed that entropy images constructed using a small sliding window (side length = 1 pulse length) adequately describe changes in scatterer properties. The area under the ROC for using small-window entropy imaging to classify tumors was 0.89, which was higher than 0.79 obtained using statistical parametric imaging. In particular, boundary artifacts were largely suppressed in the proposed imaging technique. Entropy enables using a small window for implementing ultrasound parametric imaging. PMID:28106118

  19. Small-window parametric imaging based on information entropy for ultrasound tissue characterization

    NASA Astrophysics Data System (ADS)

    Tsui, Po-Hsiang; Chen, Chin-Kuo; Kuo, Wen-Hung; Chang, King-Jen; Fang, Jui; Ma, Hsiang-Yang; Chou, Dean

    2017-01-01

    Constructing ultrasound statistical parametric images by using a sliding window is a widely adopted strategy for characterizing tissues. Deficiency in spatial resolution, the appearance of boundary artifacts, and the prerequisite data distribution limit the practicability of statistical parametric imaging. In this study, small-window entropy parametric imaging was proposed to overcome the above problems. Simulations and measurements of phantoms were executed to acquire backscattered radiofrequency (RF) signals, which were processed to explore the feasibility of small-window entropy imaging in detecting scatterer properties. To validate the ability of entropy imaging in tissue characterization, measurements of benign and malignant breast tumors were conducted (n = 63) to compare performances of conventional statistical parametric (based on Nakagami distribution) and entropy imaging by the receiver operating characteristic (ROC) curve analysis. The simulation and phantom results revealed that entropy images constructed using a small sliding window (side length = 1 pulse length) adequately describe changes in scatterer properties. The area under the ROC for using small-window entropy imaging to classify tumors was 0.89, which was higher than 0.79 obtained using statistical parametric imaging. In particular, boundary artifacts were largely suppressed in the proposed imaging technique. Entropy enables using a small window for implementing ultrasound parametric imaging.

  20. Analysis Influence of Managerial Competence, Technical Competence, and Strategic Competence on Firm Performance in Electrical Engineering Company in Bandung

    NASA Astrophysics Data System (ADS)

    Wijaya, E. R.; Irianto, D.

    2018-03-01

    The industry sectors that have an important role in the era of globalization is the electro engineering sector. The era of globalization led to intense competition. One of the negative effects of the intense competition is declining profits. Drop in profits caused many firms reduces their employees without seeking the root cause of declining profits in detail. Whereas, employee is the important resources to maintain competitive advantage. Competitive advantage can be measured by the performance of which is owned by the firm. The firm's performance can be formed of competencies that is unique, rare, irreplaceable, and difficult to imitate within the firm, one of them is the competence of the individual. According to a competency-based approach and the resource- based approach, individual competence that affect the performance of the firm is managerial competence, technical competence, and strategic competence. Questionnaire is built based on the dimensions of the firm's performance, managerial competence, technical competence, and strategic competence, are processed using partial least squares application. The results indicate that managerial competence negatively impact firm’s performance with weak ties. The technical competence and strategic competence positively affect firm’s performance with moderate ties.

  1. Sparse-grid, reduced-basis Bayesian inversion: Nonaffine-parametric nonlinear equations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Peng, E-mail: peng@ices.utexas.edu; Schwab, Christoph, E-mail: christoph.schwab@sam.math.ethz.ch

    2016-07-01

    We extend the reduced basis (RB) accelerated Bayesian inversion methods for affine-parametric, linear operator equations which are considered in [16,17] to non-affine, nonlinear parametric operator equations. We generalize the analysis of sparsity of parametric forward solution maps in [20] and of Bayesian inversion in [48,49] to the fully discrete setting, including Petrov–Galerkin high-fidelity (“HiFi”) discretization of the forward maps. We develop adaptive, stochastic collocation based reduction methods for the efficient computation of reduced bases on the parametric solution manifold. The nonaffinity and nonlinearity with respect to (w.r.t.) the distributed, uncertain parameters and the unknown solution is collocated; specifically, by themore » so-called Empirical Interpolation Method (EIM). For the corresponding Bayesian inversion problems, computational efficiency is enhanced in two ways: first, expectations w.r.t. the posterior are computed by adaptive quadratures with dimension-independent convergence rates proposed in [49]; the present work generalizes [49] to account for the impact of the PG discretization in the forward maps on the convergence rates of the Quantities of Interest (QoI for short). Second, we propose to perform the Bayesian estimation only w.r.t. a parsimonious, RB approximation of the posterior density. Based on the approximation results in [49], the infinite-dimensional parametric, deterministic forward map and operator admit N-term RB and EIM approximations which converge at rates which depend only on the sparsity of the parametric forward map. In several numerical experiments, the proposed algorithms exhibit dimension-independent convergence rates which equal, at least, the currently known rate estimates for N-term approximation. We propose to accelerate Bayesian estimation by first offline construction of reduced basis surrogates of the Bayesian posterior density. The parsimonious surrogates can then be employed for online

  2. A new process sensitivity index to identify important system processes under process model and parametric uncertainty

    DOE PAGES

    Dai, Heng; Ye, Ming; Walker, Anthony P.; ...

    2017-03-28

    A hydrological model consists of multiple process level submodels, and each submodel represents a process key to the operation of the simulated system. Global sensitivity analysis methods have been widely used to identify important processes for system model development and improvement. The existing methods of global sensitivity analysis only consider parametric uncertainty, and are not capable of handling model uncertainty caused by multiple process models that arise from competing hypotheses about one or more processes. To address this problem, this study develops a new method to probe model output sensitivity to competing process models by integrating model averaging methods withmore » variance-based global sensitivity analysis. A process sensitivity index is derived as a single summary measure of relative process importance, and the index includes variance in model outputs caused by uncertainty in both process models and their parameters. Here, for demonstration, the new index is used to assign importance to the processes of recharge and geology in a synthetic study of groundwater reactive transport modeling. The recharge process is simulated by two models that convert precipitation to recharge, and the geology process is simulated by two models of hydraulic conductivity. Each process model has its own random parameters. Finally, the new process sensitivity index is mathematically general, and can be applied to a wide range of problems in hydrology and beyond.« less

  3. A new process sensitivity index to identify important system processes under process model and parametric uncertainty

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dai, Heng; Ye, Ming; Walker, Anthony P.

    A hydrological model consists of multiple process level submodels, and each submodel represents a process key to the operation of the simulated system. Global sensitivity analysis methods have been widely used to identify important processes for system model development and improvement. The existing methods of global sensitivity analysis only consider parametric uncertainty, and are not capable of handling model uncertainty caused by multiple process models that arise from competing hypotheses about one or more processes. To address this problem, this study develops a new method to probe model output sensitivity to competing process models by integrating model averaging methods withmore » variance-based global sensitivity analysis. A process sensitivity index is derived as a single summary measure of relative process importance, and the index includes variance in model outputs caused by uncertainty in both process models and their parameters. Here, for demonstration, the new index is used to assign importance to the processes of recharge and geology in a synthetic study of groundwater reactive transport modeling. The recharge process is simulated by two models that convert precipitation to recharge, and the geology process is simulated by two models of hydraulic conductivity. Each process model has its own random parameters. Finally, the new process sensitivity index is mathematically general, and can be applied to a wide range of problems in hydrology and beyond.« less

  4. 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.

  5. Parametric estimation for reinforced concrete relief shelter for Aceh cases

    NASA Astrophysics Data System (ADS)

    Atthaillah; Saputra, Eri; Iqbal, Muhammad

    2018-05-01

    This paper was a work in progress (WIP) to discover a rapid parametric framework for post-disaster permanent shelter’s materials estimation. The intended shelters were reinforced concrete construction with bricks as its wall. Inevitably, in post-disaster cases, design variations were needed to help suited victims condition. It seemed impossible to satisfy a beneficiary with a satisfactory design utilizing the conventional method. This study offered a parametric framework to overcome slow construction-materials estimation issue against design variations. Further, this work integrated parametric tool, which was Grasshopper to establish algorithms that simultaneously model, visualize, calculate and write the calculated data to a spreadsheet in a real-time. Some customized Grasshopper components were created using GHPython scripting for a more optimized algorithm. The result from this study was a partial framework that successfully performed modeling, visualization, calculation and writing the calculated data simultaneously. It meant design alterations did not escalate time needed for modeling, visualization, and material estimation. Further, the future development of the parametric framework will be made open source.

  6. Bounded Parametric Model Checking for Elementary Net Systems

    NASA Astrophysics Data System (ADS)

    Knapik, Michał; Szreter, Maciej; Penczek, Wojciech

    Bounded Model Checking (BMC) is an efficient verification method for reactive systems. BMC has been applied so far to verification of properties expressed in (timed) modal logics, but never to their parametric extensions. In this paper we show, for the first time that BMC can be extended to PRTECTL - a parametric extension of the existential version of CTL. To this aim we define a bounded semantics and a translation from PRTECTL to SAT. The implementation of the algorithm for Elementary Net Systems is presented, together with some experimental results.

  7. Parametric resonance in the early Universe—a fitting analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Figueroa, Daniel G.; Torrentí, Francisco, E-mail: daniel.figueroa@cern.ch, E-mail: f.torrenti@csic.es

    Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in 3+1 dimensions, we parametrize the dynamics' outcome scanningmore » over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasize the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequent non-linear dynamics. We provide simple fits to the relevant time scales and particle energy fractions at each stage. Our fits can be applied to post-inflationary preheating scenarios, where the oscillatory field is the inflaton, or to spectator-field scenarios, where the oscillatory field can be e.g. a curvaton, or the Standard Model Higgs.« less

  8. flexsurv: A Platform for Parametric Survival Modeling in R

    PubMed Central

    Jackson, Christopher H.

    2018-01-01

    flexsurv is an R package for fully-parametric modeling of survival data. Any parametric time-to-event distribution may be fitted if the user supplies a probability density or hazard function, and ideally also their cumulative versions. Standard survival distributions are built in, including the three and four-parameter generalized gamma and F distributions. Any parameter of any distribution can be modeled as a linear or log-linear function of covariates. The package also includes the spline model of Royston and Parmar (2002), in which both baseline survival and covariate effects can be arbitrarily flexible parametric functions of time. The main model-fitting function, flexsurvreg, uses the familiar syntax of survreg from the standard survival package (Therneau 2016). Censoring or left-truncation are specified in ‘Surv’ objects. The models are fitted by maximizing the full log-likelihood, and estimates and confidence intervals for any function of the model parameters can be printed or plotted. flexsurv also provides functions for fitting and predicting from fully-parametric multi-state models, and connects with the mstate package (de Wreede, Fiocco, and Putter 2011). This article explains the methods and design principles of the package, giving several worked examples of its use. PMID:29593450

  9. Competency Analytics Tool: Analyzing Curriculum Using Course Competencies

    ERIC Educational Resources Information Center

    Gottipati, Swapna; Shankararaman, Venky

    2018-01-01

    The applications of learning outcomes and competency frameworks have brought better clarity to engineering programs in many universities. Several frameworks have been proposed to integrate outcomes and competencies into course design, delivery and assessment. However, in many cases, competencies are course-specific and their overall impact on the…

  10. Coupled parametric design of flow control and duct shape

    NASA Technical Reports Server (NTRS)

    Florea, Razvan (Inventor); Bertuccioli, Luca (Inventor)

    2009-01-01

    A method for designing gas turbine engine components using a coupled parametric analysis of part geometry and flow control is disclosed. Included are the steps of parametrically defining the geometry of the duct wall shape, parametrically defining one or more flow control actuators in the duct wall, measuring a plurality of performance parameters or metrics (e.g., flow characteristics) of the duct and comparing the results of the measurement with desired or target parameters, and selecting the optimal duct geometry and flow control for at least a portion of the duct, the selection process including evaluating the plurality of performance metrics in a pareto analysis. The use of this method in the design of inter-turbine transition ducts, serpentine ducts, inlets, diffusers, and similar components provides a design which reduces pressure losses and flow profile distortions.

  11. Supercritical nonlinear parametric dynamics of Timoshenko microbeams

    NASA Astrophysics Data System (ADS)

    Farokhi, Hamed; Ghayesh, Mergen H.

    2018-06-01

    The nonlinear supercritical parametric dynamics of a Timoshenko microbeam subject to an axial harmonic excitation force is examined theoretically, by means of different numerical techniques, and employing a high-dimensional analysis. The time-variant axial load is assumed to consist of a mean value along with harmonic fluctuations. In terms of modelling, a continuous expression for the elastic potential energy of the system is developed based on the modified couple stress theory, taking into account small-size effects; the kinetic energy of the system is also modelled as a continuous function of the displacement field. Hamilton's principle is employed to balance the energies and to obtain the continuous model of the system. Employing the Galerkin scheme along with an assumed-mode technique, the energy terms are reduced, yielding a second-order reduced-order model with finite number of degrees of freedom. A transformation is carried out to convert the second-order reduced-order model into a double-dimensional first order one. A bifurcation analysis is performed for the system in the absence of the axial load fluctuations. Moreover, a mean value for the axial load is selected in the supercritical range, and the principal parametric resonant response, due to the time-variant component of the axial load, is obtained - as opposed to transversely excited systems, for parametrically excited system (such as our problem here), the nonlinear resonance occurs in the vicinity of twice any natural frequency of the linear system; this is accomplished via use of the pseudo-arclength continuation technique, a direct time integration, an eigenvalue analysis, and the Floquet theory for stability. The natural frequencies of the system prior to and beyond buckling are also determined. Moreover, the effect of different system parameters on the nonlinear supercritical parametric dynamics of the system is analysed, with special consideration to the effect of the length-scale parameter.

  12. Competing risks of death in younger and older postmenopausal breast cancer patients

    PubMed Central

    Chapman, Judy-Anne W; Pritchard, Kathleen I; Goss, Paul E; Ingle, James N; Muss, Hyman B; Dent, Susan F; Vandenberg, Ted A; Findlay, Brian; Gelmon, Karen A; Wilson, Carolyn F; Shepherd, Lois E; Pollak, Michael N

    2014-01-01

    AIM: To show a new paradigm of simultaneously testing whether breast cancer therapies impact other causes of death. METHODS: MA.14 allocated 667 postmenopausal women to 5 years of tamoxifen 20 mg/daily ± 2 years of octreotide 90 mg, given by depot intramuscular injections monthly. Event-free survival was the primary endpoint of MA.14; at median 7.9 years, the tamoxifen+octreotide and tamoxifen arms had similar event-free survival (P = 0.62). Overall survival was a secondary endpoint, and the two trial arms also had similar overall survival (P = 0.86). We used the median 9.8 years follow-up to examine by intention-to-treat, the multivariate time-to-breast cancer-specific (BrCa) and other cause (OC) mortality with log-normal survival analysis adjusted by treatment and stratification factors. We tested whether baseline factors including Insulin-like growth factor 1 (IGF1), IGF binding protein-3, C-peptide, body mass index, and 25-hydroxy vitamin D were associated with (1) all cause mortality, and if so and (2) cause-specific mortality. We also fit step-wise forward cause-specific adjusted models. RESULTS: The analyses were performed on 329 patients allocated tamoxifen and 329 allocated tamoxifen+octreotide. The median age of MA.14 patients was 60.1 years: 447 (82%) < 70 years and 120 (18%) ≥ 70 years. There were 170 deaths: 106 (62.3%) BrCa; 55 (32.4%) OC, of which 24 were other malignancies, 31 other causes of death; 9 (5.3%) patients with unknown cause of death were excluded from competing risk assessments. BrCa and OC deaths were not significantly different by treatment arm (P = 0.40): tamoxifen patients experienced 50 BrCa and 32 OC deaths, while tamoxifen + octreotide patients experienced 56 BrCa and 23 OC deaths. Proportionately more deaths (P = 0.004) were from BrCa for patients < 70 years, where 70% of deaths were due to BrCa, compared to 54% for those ≥ 70 years of age. The proportion of deaths from OC increased with increasing body mass index (BMI) (P

  13. The many faces of competency.

    PubMed

    Drane, J F

    1985-04-01

    A sliding-scale model for assessing patient competency to consent to medical treatments is proposed. The least stringent standard, to be applied in the case of safe and effective treatments, assumes a valid consent if the patient is aware of what is happening and assents to the rational expectations of the physician. The second standard, applicable in the case of less certain treatments, requires that the patient understand the treatment options and have the capacity to choose or reject a treatment based on a weighing of risks and benefits. The third and most stringent standard, reserved for very dangerous treatments, bases competence to consent on an appreciation of the implications of the medical information for the patient's life and on an ability to state the reasons for the decision in terms of the medical issues and the patient's personal values.

  14. Adjudicative Competence

    PubMed Central

    Dawes, Sharron E.; Palmer, Barton W.; Jeste, Dilip V.

    2008-01-01

    Purpose of review Although the basic standards of adjudicative competence were specified by the U.S. Supreme Court in 1960, there remain a number of complex conceptual and practical issues in interpreting and applying these standards. In this report we provide a brief overview regarding the general concept of adjudicative competence and its assessment, as well as some highlights of recent empirical studies on this topic. Findings Most adjudicative competence assessments are conducted by psychiatrists or psychologists. There are no universal certification requirements, but some states are moving toward required certification of forensic expertise for those conducting such assessments. Recent data indicate inconsistencies in application of the existing standards even among forensic experts, but the recent publication of consensus guidelines may foster improvements in this arena. There are also ongoing efforts to develop and validate structured instruments to aid competency evaluations. Telemedicine-based competency interviews may facilitate evaluation by those with specific expertise for evaluation of complex cases. There is also interest in empirical development of educational methods to enhance adjudicative competence. Summary Adjudicative competence may be difficult to measure accurately, but the assessments and tools available are advancing. More research is needed on methods of enhancing decisional capacity among those with impaired competence. PMID:18650693

  15. Formation of parametric images using mixed-effects models: a feasibility study.

    PubMed

    Huang, Husan-Ming; Shih, Yi-Yu; Lin, Chieh

    2016-03-01

    Mixed-effects models have been widely used in the analysis of longitudinal data. By presenting the parameters as a combination of fixed effects and random effects, mixed-effects models incorporating both within- and between-subject variations are capable of improving parameter estimation. In this work, we demonstrate the feasibility of using a non-linear mixed-effects (NLME) approach for generating parametric images from medical imaging data of a single study. By assuming that all voxels in the image are independent, we used simulation and animal data to evaluate whether NLME can improve the voxel-wise parameter estimation. For testing purposes, intravoxel incoherent motion (IVIM) diffusion parameters including perfusion fraction, pseudo-diffusion coefficient and true diffusion coefficient were estimated using diffusion-weighted MR images and NLME through fitting the IVIM model. The conventional method of non-linear least squares (NLLS) was used as the standard approach for comparison of the resulted parametric images. In the simulated data, NLME provides more accurate and precise estimates of diffusion parameters compared with NLLS. Similarly, we found that NLME has the ability to improve the signal-to-noise ratio of parametric images obtained from rat brain data. These data have shown that it is feasible to apply NLME in parametric image generation, and the parametric image quality can be accordingly improved with the use of NLME. With the flexibility to be adapted to other models or modalities, NLME may become a useful tool to improve the parametric image quality in the future. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Ince-Strutt stability charts for ship parametric roll resonance in irregular waves

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Yang, He-zhen; Xiao, Fei; Xu, Pei-ji

    2017-08-01

    Ince-Strutt stability chart of ship parametric roll resonance in irregular waves is conducted and utilized for the exploration of the parametric roll resonance in irregular waves. Ship parametric roll resonance will lead to large amplitude roll motion and even wreck. Firstly, the equation describing the parametric roll resonance in irregular waves is derived according to Grim's effective theory and the corresponding Ince-Strutt stability charts are obtained. Secondly, the differences of stability charts for the parametric roll resonance in irregular and regular waves are compared. Thirdly, wave phases and peak periods are taken into consideration to obtain a more realistic sea condition. The influence of random wave phases should be taken into consideration when the analyzed points are located near the instability boundary. Stability charts for different wave peak periods are various. Stability charts are helpful for the parameter determination in design stage to better adapt to sailing condition. Last, ship variables are analyzed according to stability charts by a statistical approach. The increase of the metacentric height will help improve ship stability.

  17. Developing entrepreneurial competencies in the healthcare management undergraduate classroom.

    PubMed

    Rubino, Louis; Freshman, Brenda

    2005-01-01

    Recently, entrepreneurial behavior is becoming more accepted in the healthcare field. This article describes an attempt to foster development of positive entrepreneurial competencies in the undergraduate health administration classroom. Through a literature review on entrepreneurs, eight competency clusters are identified; decision making, strategic thinking, risk taking, confidence building, communicating ideas, motivating team members, tolerance of ambiguity, and internal locus of control. These clusters are used to promote entrepreneurial skills for students though identified learning-centered activities and supplement an instructional style that facilitates thoughtful reflection.

  18. Temperature Dependence of Parametric Phenomenon in Airborne Ultrasound for Temperature Measurement

    NASA Astrophysics Data System (ADS)

    Kon, Akihiko; Wakatsuki, Naoto; Mizutani, Koichi

    2008-08-01

    The temperature dependence of parametric phenomenon in air was experimentally studied. It was confirmed from experimental data that the amplitude of upper sideband sound with a frequency of 36.175 kHz, which is caused by parametric phenomenon between high-power ultrasound with a frequency of 20.175 kHz and another normal sound with a frequency of 16.0 kHz, is proportional to -0.88×10-4×(T+273.15). This temperature dependence of the amplitude of upper sideband sound caused by the parametric phenomenon suggests a simple and effective method of temperature measurement.

  19. Sgr A* Emission Parametrizations from GRMHD Simulations

    NASA Astrophysics Data System (ADS)

    Anantua, Richard; Ressler, Sean; Quataert, Eliot

    2018-06-01

    Galactic Center emission near the vicinity of the central black hole, Sagittarius (Sgr) A*, is modeled using parametrizations involving the electron temperature, which is found from general relativistic magnetohydrodynamic (GRMHD) simulations to be highest in the disk-outflow corona. Jet-motivated prescriptions generalizing equipartition of particle and magnetic energies, e.g., by scaling relativistic electron energy density to powers of the magnetic field strength, are also introduced. GRMHD jet (or outflow)/accretion disk/black hole (JAB) simulation postprocessing codes IBOTHROS and GRMONTY are employed in the calculation of images and spectra. Various parametric models reproduce spectral and morphological features, such as the sub-mm spectral bump in electron temperature models and asymmetric photon rings in equipartition-based models. The Event Horizon Telescope (EHT) will provide unprecedentedly high-resolution 230+ GHz observations of the "shadow" around Sgr A*'s supermassive black hole, which the synthetic models presented here will reverse-engineer. Both electron temperature and equipartition-based models can be constructed to be compatible with EHT size constraints for the emitting region of Sgr A*. This program sets the groundwork for devising a unified emission parametrization flexible enough to model disk, corona and outflow/jet regions with a small set of parameters including electron heating fraction and plasma beta.

  20. Using role play to develop cultural competence.

    PubMed

    Shearer, Ruth; Davidhizar, Ruth

    2003-06-01

    Role play is a useful teaching strategy for nursing education. This strategy can simulate patient behaviors, as well as demonstrate nursing interventions that students must learn to be clinically competent. Role play is a dramatic technique that encourages participation to improvise behaviors that may be encountered in nurse-patient situations. Using this technique, participants may test behaviors and decisions in an experimental atmosphere without risk of negative effects in a relationship. Role play is useful in developing cultural competence because participants may experience diverse roles. Cultural competence is the ability to care for patients in a culturally sensitive and appropriate manner. In role play, students may participate as culturally diverse patients or as nurses encountering patients from different cultures. Various teaching strategies facilitate successful use of role play in the classroom, including defining a time frame, selected roles, specific objectives, references, and grading criteria. To optimize learning, the importance of exploration and analysis must be emphasized. Many benefits and potential problems accompany use of role play.

  1. AAOHN Competencies.

    PubMed

    2015-11-01

    The AAOHN Competency document is one of the core documents that define occupational health nursing practice. This article provides a description of the process used to update the competencies, as well as a description of the new competencies. © 2015 The Author(s).

  2. Finding Rational Parametric Curves of Relative Degree One or Two

    ERIC Educational Resources Information Center

    Boyles, Dave

    2010-01-01

    A plane algebraic curve, the complete set of solutions to a polynomial equation: f(x, y) = 0, can in many cases be drawn using parametric equations: x = x(t), y = y(t). Using algebra, attempting to parametrize by means of rational functions of t, one discovers quickly that it is not the degree of f but the "relative degree," that describes how…

  3. Multi-parametric variational data assimilation for hydrological forecasting

    NASA Astrophysics Data System (ADS)

    Alvarado-Montero, R.; Schwanenberg, D.; Krahe, P.; Helmke, P.; Klein, B.

    2017-12-01

    Ensemble forecasting is increasingly applied in flow forecasting systems to provide users with a better understanding of forecast uncertainty and consequently to take better-informed decisions. A common practice in probabilistic streamflow forecasting is to force deterministic hydrological model with an ensemble of numerical weather predictions. This approach aims at the representation of meteorological uncertainty but neglects uncertainty of the hydrological model as well as its initial conditions. Complementary approaches use probabilistic data assimilation techniques to receive a variety of initial states or represent model uncertainty by model pools instead of single deterministic models. This paper introduces a novel approach that extends a variational data assimilation based on Moving Horizon Estimation to enable the assimilation of observations into multi-parametric model pools. It results in a probabilistic estimate of initial model states that takes into account the parametric model uncertainty in the data assimilation. The assimilation technique is applied to the uppermost area of River Main in Germany. We use different parametric pools, each of them with five parameter sets, to assimilate streamflow data, as well as remotely sensed data from the H-SAF project. We assess the impact of the assimilation in the lead time performance of perfect forecasts (i.e. observed data as forcing variables) as well as deterministic and probabilistic forecasts from ECMWF. The multi-parametric assimilation shows an improvement of up to 23% for CRPS performance and approximately 20% in Brier Skill Scores with respect to the deterministic approach. It also improves the skill of the forecast in terms of rank histogram and produces a narrower ensemble spread.

  4. Ultra-flat wideband single-pump Raman-enhanced parametric amplification.

    PubMed

    Gordienko, V; Stephens, M F C; El-Taher, A E; Doran, N J

    2017-03-06

    We experimentally optimize a single pump fiber optical parametric amplifier in terms of gain spectral bandwidth and gain variation (GV). We find that optimal performance is achieved with the pump tuned to the zero-dispersion wavelength of dispersion stable highly nonlinear fiber (HNLF). We demonstrate further improvement of parametric gain bandwidth and GV by decreasing the HNLF length. We discover that Raman and parametric gain spectra produced by the same pump may be merged together to enhance overall gain bandwidth, while keeping GV low. Consequently, we report an ultra-flat gain of 9.6 ± 0.5 dB over a range of 111 nm (12.8 THz) on one side of the pump. Additionally, we demonstrate amplification of a 60 Gbit/s QPSK signal tuned over a portion of the available bandwidth with OSNR penalty less than 1 dB for Q2 below 14 dB.

  5. A micromachined device describing over a hundred orders of parametric resonance

    NASA Astrophysics Data System (ADS)

    Jia, Yu; Du, Sijun; Arroyo, Emmanuelle; Seshia, Ashwin A.

    2018-04-01

    Parametric resonance in mechanical oscillators can onset from the periodic modulation of at least one of the system parameters, and the behaviour of the principal (1st order) parametric resonance has long been well established. However, the theoretically predicted higher orders of parametric resonance, in excess of the first few orders, have mostly been experimentally elusive due to the fast diminishing instability intervals. A recent paper experimentally reported up to 28 orders in a micromachined membrane oscillator. This paper reports the design and characterisation of a micromachined membrane oscillator with a segmented proof mass topology, in an attempt to amplify the inherent nonlinearities within the membrane layer. The resultant oscillator device exhibited up to over a hundred orders of parametric resonance, thus experimentally validating these ultra-high orders as well as overlapping instability transitions between these higher orders. This research introduces design possibilities for the transducer and dynamic communities, by exploiting the behaviour of these previously elusive higher order resonant regimes.

  6. Cluster B personality symptoms in persons at genetic risk for schizophrenia are associated with social competence and activation of the right temporo-parietal junction during emotion processing.

    PubMed

    Goldschmidt, Micaela Giuliana; Villarreal, Mirta Fabiana; de Achával, Delfina; Drucaroff, Lucas Javier; Costanzo, Elsa Yolanda; Castro, Mariana Nair; Pahissa, Jaime; Camprodon, Joan; Nemeroff, Charles; Guinjoan, Salvador Martín

    2014-01-30

    Personality disorders are common in nonpsychotic siblings of patients with schizophrenia, and some personality traits in this group may be associated with an increased risk for full-blown psychosis. We sought to establish if faulty right-hemisphere activation induced by social cognitive tasks, as previously described in patients with schizophrenia, is associated with specific personality symptoms in their unaffected siblings. We observed that cluster B personality symptoms in this group were inversely related to activation in the right temporo parietal junction (rTPJ, a structure critical in social cognitive processing) in response to a basic emotion processing task and also to social competence, whereas in contrast to our initial hypothesis, cluster A traits were not associated with right hemisphere activation during emotion processing or with social competence. These findings suggest the existence of clinical traits in at-risk individuals which share a common neurobiological substrate with schizophrenia, in regards to social performance. © 2013 Published by Elsevier Ireland Ltd.

  7. Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort.

    PubMed

    Lindqvist, P G; Epstein, E; Nielsen, K; Landin-Olsson, M; Ingvar, C; Olsson, H

    2016-10-01

    Women with active sunlight exposure habits experience a lower mortality rate than women who avoid sun exposure; however, they are at an increased risk of skin cancer. We aimed to explore the differences in main causes of death according to sun exposure. We assessed the differences in sun exposure as a risk factor for all-cause mortality in a competing risk scenario for 29 518 Swedish women in a prospective 20-year follow-up of the Melanoma in Southern Sweden (MISS) cohort. Women were recruited from 1990 to 1992 (aged 25-64 years at the start of the study). We obtained detailed information at baseline on sun exposure habits and potential confounders. The data were analysed using modern survival statistics. Women with active sun exposure habits were mainly at a lower risk of cardiovascular disease (CVD) and noncancer/non-CVD death as compared to those who avoided sun exposure. As a result of their increased survival, the relative contribution of cancer death increased in these women. Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking. Compared to the highest sun exposure group, life expectancy of avoiders of sun exposure was reduced by 0.6-2.1 years. The longer life expectancy amongst women with active sun exposure habits was related to a decrease in CVD and noncancer/non-CVD mortality, causing the relative contribution of death due to cancer to increase. © 2016 The Association for the Publication of the Journal of Internal Medicine.

  8. Three-wave interaction solitons in optical parametric amplification.

    PubMed

    Ibragimov, E; Struthers, A A; Kaup, D J; Khaydarov, J D; Singer, K D

    1999-05-01

    This paper applies three-wave interaction (TWI)-soliton theory to optical parametric amplification when the signal, idler, and pump wave can all contain TWI solitons. We use an analogy between two different velocity regimes to compare the theory with output from an experimental synchronously pumped optical parametric amplifier. The theory explains the observed inability to compress the intermediate group-velocity wave and 20-fold pulse compression in this experiment. The theory and supporting numerics show that one can effectively control the shape and energy of the optical pulses by shifting the TWI solitons in the pulses.

  9. Ranking Forestry Investments With Parametric Linear Programming

    Treesearch

    Paul A. Murphy

    1976-01-01

    Parametric linear programming is introduced as a technique for ranking forestry investments under multiple constraints; it combines the advantages of simple tanking and linear programming as capital budgeting tools.

  10. A Parametric Analysis of HELSTAR

    DTIC Science & Technology

    1983-12-01

    AFIT/GSO/OS/83D-7 S....A PARAMETRIC ANALYSIS OF HELSTAR THESIS James Miklasevich Captain, USAF AFIT/CSO/OS/83D-7 ’- 3 - Reproduced From J𔄁 04. • ’ S...1 Statement of Problem. ...... ................ ......... 3 Objectives of the Research. .... ............ . . . 3 ...Launch Scenarios ................. 39 Launch Sequencel................... 39 Launch Sequence 2 . . . . . .. . . . .. . . . . . 1 Launch Sequence 3

  11. Further Empirical Results on Parametric Versus Non-Parametric IRT Modeling of Likert-Type Personality Data

    ERIC Educational Resources Information Center

    Maydeu-Olivares, Albert

    2005-01-01

    Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in…

  12. A Unified and Comprehensible View of Parametric and Kernel Methods for Genomic Prediction with Application to Rice.

    PubMed

    Jacquin, Laval; Cao, Tuong-Vi; Ahmadi, Nourollah

    2016-01-01

    One objective of this study was to provide readers with a clear and unified understanding of parametric statistical and kernel methods, used for genomic prediction, and to compare some of these in the context of rice breeding for quantitative traits. Furthermore, another objective was to provide a simple and user-friendly R package, named KRMM, which allows users to perform RKHS regression with several kernels. After introducing the concept of regularized empirical risk minimization, the connections between well-known parametric and kernel methods such as Ridge regression [i.e., genomic best linear unbiased predictor (GBLUP)] and reproducing kernel Hilbert space (RKHS) regression were reviewed. Ridge regression was then reformulated so as to show and emphasize the advantage of the kernel "trick" concept, exploited by kernel methods in the context of epistatic genetic architectures, over parametric frameworks used by conventional methods. Some parametric and kernel methods; least absolute shrinkage and selection operator (LASSO), GBLUP, support vector machine regression (SVR) and RKHS regression were thereupon compared for their genomic predictive ability in the context of rice breeding using three real data sets. Among the compared methods, RKHS regression and SVR were often the most accurate methods for prediction followed by GBLUP and LASSO. An R function which allows users to perform RR-BLUP of marker effects, GBLUP and RKHS regression, with a Gaussian, Laplacian, polynomial or ANOVA kernel, in a reasonable computation time has been developed. Moreover, a modified version of this function, which allows users to tune kernels for RKHS regression, has also been developed and parallelized for HPC Linux clusters. The corresponding KRMM package and all scripts have been made publicly available.

  13. 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…

  14. Parametric study of prospective early commercial MHD power plants (PSPEC). General Electric Company, task 1: Parametric analysis

    NASA Technical Reports Server (NTRS)

    Marston, C. H.; Alyea, F. N.; Bender, D. J.; Davis, L. K.; Dellinger, T. C.; Hnat, J. G.; Komito, E. H.; Peterson, C. A.; Rogers, D. A.; Roman, A. J.

    1980-01-01

    The performance and cost of moderate technology coal-fired open cycle MHD/steam power plant designs which can be expected to require a shorter development time and have a lower development cost than previously considered mature OCMHD/steam plants were determined. Three base cases were considered: an indirectly-fired high temperature air heater (HTAH) subsystem delivering air at 2700 F, fired by a state of the art atmospheric pressure gasifier, and the HTAH subsystem was deleted and oxygen enrichment was used to obtain requisite MHD combustion temperature. Coal pile to bus bar efficiencies in ease case 1 ranged from 41.4% to 42.9%, and cost of electricity (COE) was highest of the three base cases. For base case 2 the efficiency range was 42.0% to 45.6%, and COE was lowest. For base case 3 the efficiency range was 42.9% to 44.4%, and COE was intermediate. The best parametric cases in bases cases 2 and 3 are recommended for conceptual design. Eventual choice between these approaches is dependent on further evaluation of the tradeoffs among HTAH development risk, O2 plant integration, and further refinements of comparative costs.

  15. Suicidal thoughts and emotion competence

    PubMed Central

    Paradiso, Sergio; Beadle, Janelle; Raymont, Vanessa; Grafman, Jordan

    2016-01-01

    Background During deployment and upon returning home, Veterans experience emotional challenges that test their social and psychological adaptation and place them at risk for suicidal thinking. Individual variability in skill-based capacity to adaptively perceive, understand, correctly use and manage emotions (called emotional competence) may play a role in the development of psychological suffering and suicidal thinking. Based on research in healthy and clinical samples, poor emotional competence was predicted to be associated with suicidal thinking among returning Veterans. Methods Participants were selected from the W.F. Caveness Vietnam Head Injury Study (VHIS) registry that in the late 1960’s began prospectively assessing 1221 Veterans (Raymont, V., Salazar, A. M., Krueger, F., & Grafman, J., 2011). The study sample was comprised of Veterans examined between 2003–2006 and included 185 participants who at the time of assessment with the Beck Depression Inventory (BDI) did (N=46) or did not endorse (N=139) suicidal thinking then or during the previous two weeks and received performance based measures of emotional competence (MSCEIT, version 2.0) and theory of mind. MSCEIT subtests and theory of mind tasks were condensed via principal component analysis: Component 1 (Emotion Processing) included Using, Understanding and Managing emotions tasks, and Component 2 (Emotion Perception) included Perceiving emotions. Results Veterans endorsing suicidal thoughts showed poorer Emotion Processing whereas Emotion Perception and theory of mind tasks did not show significant group effects. In addition, Veterans who endorsed thoughts of suicide were deployed at a younger age, had lower education, and tended to report more negative experiences in social interactions upon return to the US. Conclusions The capacity to understand, use and manage emotionally charged stimuli and situations may represent risk factors for suicidal thinking among Veterans. PMID:27171549

  16. Revisiting Parametric Types and Virtual Classes

    NASA Astrophysics Data System (ADS)

    Madsen, Anders Bach; Ernst, Erik

    This paper presents a conceptually oriented updated view on the relationship between parametric types and virtual classes. The traditional view is that parametric types excel at structurally oriented composition and decomposition, and virtual classes excel at specifying mutually recursive families of classes whose relationships are preserved in derived families. Conversely, while class families can be specified using a large number of F-bounded type parameters, this approach is complex and fragile; and it is difficult to use traditional virtual classes to specify object composition in a structural manner, because virtual classes are closely tied to nominal typing. This paper adds new insight about the dichotomy between these two approaches; it illustrates how virtual constraints and type refinements, as recently introduced in gbeta and Scala, enable structural treatment of virtual types; finally, it shows how a novel kind of dynamic type check can detect compatibility among entire families of classes.

  17. Parametric Model of an Aerospike Rocket Engine

    NASA Technical Reports Server (NTRS)

    Korte, J. J.

    2000-01-01

    A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHTI multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.

  18. Parametric Model of an Aerospike Rocket Engine

    NASA Technical Reports Server (NTRS)

    Korte, J. J.

    2000-01-01

    A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHT multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.

  19. Morality or competence? The importance of affirming the appropriate dimension of self-integrity.

    PubMed

    Jessop, Donna C; Sparks, Paul; Jessop, Laura; Dodds, Lauren; Lynch, Sarah

    2016-11-01

    Two studies explored the relative efficacy of a morality-based versus a competence-based self-affirmation manipulation at increasing acceptance of personally relevant health risk information. In accordance with prior theorizing (e.g., Cohen & Sherman, 2014), it was hypothesized that the morality affirmation would be more effective than the competence affirmation in such contexts, as the former targets a different domain to that threatened by the health risk information. Both studies employed a cross-sectional experimental design. Participants were presented with a morality affirmation, competence affirmation, or no affirmation control prior to reading a message about the risks of (1) not engaging in daily dental flossing (Study 1) and (2) red meat consumption (Study 2). Participants subsequently completed a number of measures assessing acceptance of the message. In line with predictions, findings from both studies demonstrated that the morality affirmation precipitated greater acceptance of personally relevant health risk information compared to the competence affirmation, as reflected in more positive attitudes (Studies 1 and 2) and intentions (Study 1). Study 2's findings further suggested that the superior efficacy of the morality affirmation in health-related contexts could not simply be attributed to a general tendency for this affirmation to outperform the competence affirmation. The nature of the value affirmed may be a critical factor in determining the success of self-affirmation manipulations in health-related domains. Statement of contribution What is already known on this subject? Self-affirmation has been shown to promote openness to personally relevant health risk information across a variety of behavioural domains. The most frequently utilized self-affirmation manipulation involves participants reflecting on a personally important value; however, participants typically self-select the value they reflect on. This means that the nature of the value

  20. Setting Performance Standards for Technical and Nontechnical Competence in General Surgery.

    PubMed

    Szasz, Peter; Bonrath, Esther M; Louridas, Marisa; Fecso, Andras B; Howe, Brett; Fehr, Adam; Ott, Michael; Mack, Lloyd A; Harris, Kenneth A; Grantcharov, Teodor P

    2017-07-01

    The objectives of this study were to (1) create a technical and nontechnical performance standard for the laparoscopic cholecystectomy, (2) assess the classification accuracy and (3) credibility of these standards, (4) determine a trainees' ability to meet both standards concurrently, and (5) delineate factors that predict standard acquisition. Scores on performance assessments are difficult to interpret in the absence of established standards. Trained raters observed General Surgery residents performing laparoscopic cholecystectomies using the Objective Structured Assessment of Technical Skill (OSATS) and the Objective Structured Assessment of Non-Technical Skills (OSANTS) instruments, while as also providing a global competent/noncompetent decision for each performance. The global decision was used to divide the trainees into 2 contrasting groups and the OSATS or OSANTS scores were graphed per group to determine the performance standard. Parametric statistics were used to determine classification accuracy and concurrent standard acquisition, receiver operator characteristic (ROC) curves were used to delineate predictive factors. Thirty-six trainees were observed 101 times. The technical standard was an OSATS of 21.04/35.00 and the nontechnical standard an OSANTS of 22.49/35.00. Applying these standards, competent/noncompetent trainees could be discriminated in 94% of technical and 95% of nontechnical performances (P < 0.001). A 21% discordance between technically and nontechnically competent trainees was identified (P < 0.001). ROC analysis demonstrated case experience and trainee level were both able to predict achieving the standards with an area under the curve (AUC) between 0.83 and 0.96 (P < 0.001). The present study presents defensible standards for technical and nontechnical performance. Such standards are imperative to implementing summative assessments into surgical training.

  1. Markovian Dynamics of Josephson Parametric Amplification

    NASA Astrophysics Data System (ADS)

    Kaiser, Waldemar; Haider, Michael; Russer, Johannes A.; Russer, Peter; Jirauschek, Christian

    2017-09-01

    In this work, we derive the dynamics of the lossy DC pumped non-degenerate Josephson parametric amplifier (DCPJPA). The main element in a DCPJPA is the superconducting Josephson junction. The DC bias generates the AC Josephson current varying the nonlinear inductance of the junction. By this way the Josephson junction acts as the pump oscillator as well as the time varying reactance of the parametric amplifier. In quantum-limited amplification, losses and noise have an increased impact on the characteristics of an amplifier. We outline the classical model of the lossy DCPJPA and derive the available noise power spectral densities. A classical treatment is not capable of including properties like spontaneous emission which is mandatory in case of amplification at the quantum limit. Thus, we derive a quantum mechanical model of the lossy DCPJPA. Thermal losses are modeled by the quantum Langevin approach, by coupling the quantized system to a photon heat bath in thermodynamic equilibrium. The mode occupation in the bath follows the Bose-Einstein statistics. Based on the second quantization formalism, we derive the Heisenberg equations of motion of both resonator modes. We assume the dynamics of the system to follow the Markovian approximation, i.e. the system only depends on its actual state and is memory-free. We explicitly compute the time evolution of the contributions to the signal mode energy and give numeric examples based on different damping and coupling constants. Our analytic results show, that this model is capable of including thermal noise into the description of the DC pumped non-degenerate Josephson parametric amplifier.

  2. Developmental cascades: Externalizing, internalizing, and academic competence from middle childhood to early adolescence

    PubMed Central

    Moilanen, Kristin L.; Shaw, Daniel S.; Maxwell, Kari L.

    2011-01-01

    The current study was initiated to increase understanding of developmental cascades in childhood in a sample of at-risk boys (N = 291; 52% White). Mothers, teachers, and boys reported on boys’ externalizing problems, internalizing difficulties, and academic competence. Consistent with hypotheses regarding school-related transitions, high levels of externalizing problems were associated with both low levels of academic competence and high levels of internalizing problems during the early school-age period, and with elevations in internalizing problems during the transition to adolescence. Low levels of academic competence were associated with high levels of internalizing problems in middle childhood, and with high levels of externalizing problems during the transition from elementary school to middle school. Shared risk factors played a minimal role in these developmental cascades. Results suggest that there are cascading effects of externalizing problems and academic competence in childhood and early adolescence, and that some cascading effects are more likely to occur during periods of school-related transitions. Implications of developmental cascade effects for research and intervention are discussed. PMID:20576184

  3. Associations between Eating Competence and Cardiovascular Disease Biomarkers

    ERIC Educational Resources Information Center

    Psota, Tricia L.; Lohse, Barbara; West, Sheila G.

    2007-01-01

    Objective: Explore the relationship between eating competence (EC) and biomarkers of risk for cardiovascular disease (CVD). Design: Secondary analysis of data collected for a larger, 2-way crossover clinical trial. Setting: Outpatient clinical research center. Participants: Forty-eight hypercholesterolemic (LDL cholesterol [greater than or equal]…

  4. Multicast Parametric Synchronous Sampling

    DTIC Science & Technology

    2011-09-01

    enhancement in a parametric mixer device. Fig. 4 shows the principle of generating uniform, high quality replicas extending over previously un-attainable...critical part of the MPASS architecture and is responsible for the direct and continuous acquisition of data across all of the multicast signal copies...ii) ability to copy THz signals with impunity to tens of replicas ; (iii) all-optical delays > 1.9 us; (iv) 10’s of THz-fast all-optical sampling of

  5. Parametrization of Drag and Turbulence for Urban Neighbourhoods with Trees

    NASA Astrophysics Data System (ADS)

    Krayenhoff, E. S.; Santiago, J.-L.; Martilli, A.; Christen, A.; Oke, T. R.

    2015-08-01

    Urban canopy parametrizations designed to be coupled with mesoscale models must predict the integrated effect of urban obstacles on the flow at each height in the canopy. To assess these neighbourhood-scale effects, results of microscale simulations may be horizontally-averaged. Obstacle-resolving computational fluid dynamics (CFD) simulations of neutrally-stratified flow through canopies of blocks (buildings) with varying distributions and densities of porous media (tree foliage) are conducted, and the spatially-averaged impacts on the flow of these building-tree combinations are assessed. The accuracy with which a one-dimensional (column) model with a one-equation (-) turbulence scheme represents spatially-averaged CFD results is evaluated. Individual physical mechanisms by which trees and buildings affect flow in the column model are evaluated in terms of relative importance. For the treed urban configurations considered, effects of buildings and trees may be considered independently. Building drag coefficients and length scale effects need not be altered due to the presence of tree foliage; therefore, parametrization of spatially-averaged flow through urban neighbourhoods with trees is greatly simplified. The new parametrization includes only source and sink terms significant for the prediction of spatially-averaged flow profiles: momentum drag due to buildings and trees (and the associated wake production of turbulent kinetic energy), modification of length scales by buildings, and enhanced dissipation of turbulent kinetic energy due to the small scale of tree foliage elements. Coefficients for the Santiago and Martilli (Boundary-Layer Meteorol 137: 417-439, 2010) parametrization of building drag coefficients and length scales are revised. Inclusion of foliage terms from the new parametrization in addition to the Santiago and Martilli building terms reduces root-mean-square difference (RMSD) of the column model streamwise velocity component and turbulent

  6. Competency champions in the clinical competency committee: a successful strategy to implement milestone evaluations and competency coaching.

    PubMed

    Ketteler, Erika R; Auyang, Edward D; Beard, Kathy E; McBride, Erica L; McKee, Rohini; Russell, John C; Szoka, Nova L; Nelson, M Timothy

    2014-01-01

    To create a clinical competency committee (CCC) that (1) centers on the competency-based milestones, (2) is simple to implement, (3) creates competency expertise, and (4) guides remediation and coaching of residents who are not progressing in milestone performance evaluations. We created a CCC that meets monthly and at each meeting reviews a resident class for milestone performance, a competency (by a faculty competency champion), a resident rotation service, and any other resident or issue of concern. University surgical residency program. The CCC members include the program director, associate program directors, director of surgical curriculum, competency champions, departmental chair, 2 at-large faculty members, and the administrative chief residents. Seven residents were placed on remediation (later renamed as coaching) during the academic year after falling behind on milestone progression in one or more competencies. An additional 4 residents voluntarily placed themselves on remediation for medical knowledge after receiving in-training examination scores that the residents (not the CCC membership) considered substandard. All but 2 of the remediated/coached residents successfully completed all area milestone performance but some chose to stay on the medical knowledge competency strategy. Monthly meetings of the CCC make milestone evaluation less burdensome. In addition, the expectations of the residents are clearer and more tangible. "Competency champions" who are familiar with the milestones allow effective coaching strategies and documentation of clear performance improvements in competencies for successful completion of residency training. Residents who do not reach appropriate milestone performance can then be placed in remediation for more formal performance evaluation. The function of our CCC has also allowed us opportunity to evaluate the required rotations to ensure that they offer experiences that help residents achieve competency performance necessary

  7. Convergence optimization of parametric MLEM reconstruction for estimation of Patlak plot parameters.

    PubMed

    Angelis, Georgios I; Thielemans, Kris; Tziortzi, Andri C; Turkheimer, Federico E; Tsoumpas, Charalampos

    2011-07-01

    In dynamic positron emission tomography data many researchers have attempted to exploit kinetic models within reconstruction such that parametric images are estimated directly from measurements. This work studies a direct parametric maximum likelihood expectation maximization algorithm applied to [(18)F]DOPA data using reference-tissue input function. We use a modified version for direct reconstruction with a gradually descending scheme of subsets (i.e. 18-6-1) initialized with the FBP parametric image for faster convergence and higher accuracy. The results compared with analytic reconstructions show quantitative robustness (i.e. minimal bias) and clinical reproducibility within six human acquisitions in the region of clinical interest. Bland-Altman plots for all the studies showed sufficient quantitative agreement between the direct reconstructed parametric maps and the indirect FBP (--0.035x+0.48E--5). Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Identifying the core competencies of mental health telephone triage.

    PubMed

    Sands, Natisha; Elsom, Stephen; Gerdtz, Marie; Henderson, Kathryn; Keppich-Arnold, Sandra; Droste, Nicolas; Prematunga, Roshani K; Wereta, Zewdu W

    2013-11-01

    The primary aim of this study was to identify the core competencies of mental health telephone triage, including key role tasks, skills, knowledge and responsibilities, in which clinicians are required to be competent to perform safe and effective triage. Recent global trends indicate an increased reliance on telephone-based health services to facilitate access to health care across large populations. The trend towards telephone-based health services has also extended to mental health settings, evidenced by the growing number of mental health telephone triage services providing 24-hour access to specialist mental health assessment and treatment. Mental health telephone triage services are critical to the early identification of mental health problems and the provision of timely, appropriate interventions. In spite of the rapid growth in mental health telephone triage and the important role these services play in the assessment and management of mental illness and related risks, there has been very little research investigating this area of practice. An observational design was employed to address the research aims. Structured observations (using dual wireless headphones) were undertaken on 197 occasions of mental health telephone triage over a three-month period from January to March 2011. The research identified seven core areas of mental health telephone triage practice in which clinicians are required to be competent in to perform effective mental health telephone triage, including opening the call; performing mental status examination; risk assessment; planning and action; termination of call; referral and reporting; and documentation. The findings of this research contribute to the evidence base for mental health telephone triage by articulating the core competencies for practice. The mental health telephone triage competencies identified in this research may be used to define an evidence-based framework for mental health telephone triage practice that aims to

  9. Moral competency: meta-competence of nursing care

    PubMed Central

    Zafarnia, Niloofar; Abbaszadeh, Abbas; Borhani, Fariba; Ebadi, Abbas; Nakhaee, Nouzar

    2017-01-01

    Introduction To follow the progress of technology and increasing domain of nurses’ duties, ethical challenges can be observed more than ever. Therefore, the growing and dynamic system of nursing requires nurses with professional and ethical competence who can provide optimal care. The aim of the present study was to define and explain dimensions of moral competency among the clinical nurses of Iran. Methods This qualitative content analysis study was carried out in the years 2014 and 2015 in Iran. Data were collected through in-depth semistructured interviews and field notes. The resulting data were analyzed by Graneheim and Lundman’s method of conventional content analysis. The participants were 12 clinical nurses who were selected using purposive convenient sampling and continued interviews until data saturation. Results Themes obtained in the present study were posited in three main categories of “moral character,” with subcategories of altruism, search for meaning, be pioneering, perfectionism, self-control, honesty, and forgiveness; “moral care” with subcategories of dignified care, safe care, fair care, and holistic care; and “moral decision-making” with subcategories of moral sensitivity, moral thinking, moral reasoning, and moral courage. Conclusions Findings of the present study suggest that nurses’ moral competency is an adorable character with a wide range that includes moral virtues and character, moral decision-making, and ultimately providing moral care; therefore, moral competency is a meta-competence in the field of nursing. Because there are many competencies in different fields. PMID:28848630

  10. Surface spontaneous parametric down-conversion.

    PubMed

    Perina, Jan; Luks, Antonín; Haderka, Ondrej; Scalora, Michael

    2009-08-07

    Surface spontaneous parametric down-conversion is predicted as a consequence of continuity requirements for electric- and magnetic-field amplitudes at a discontinuity of chi;{(2)} nonlinearity. A generalization of the usual two-photon spectral amplitude is suggested to describe this effect. Examples of nonlinear layered structures and periodically poled nonlinear crystals show that surface contributions to spontaneous down-conversion can be important.

  11. Parametric Instability Rates in Periodically Driven Band Systems

    NASA Astrophysics Data System (ADS)

    Lellouch, S.; Bukov, M.; Demler, E.; Goldman, N.

    2017-04-01

    In this work, we analyze the dynamical properties of periodically driven band models. Focusing on the case of Bose-Einstein condensates, and using a mean-field approach to treat interparticle collisions, we identify the origin of dynamical instabilities arising from the interplay between the external drive and interactions. We present a widely applicable generic numerical method to extract instability rates and link parametric instabilities to uncontrolled energy absorption at short times. Based on the existence of parametric resonances, we then develop an analytical approach within Bogoliubov theory, which quantitatively captures the instability rates of the system and provides an intuitive picture of the relevant physical processes, including an understanding of how transverse modes affect the formation of parametric instabilities. Importantly, our calculations demonstrate an agreement between the instability rates determined from numerical simulations and those predicted by theory. To determine the validity regime of the mean-field analysis, we compare the latter to the weakly coupled conserving approximation. The tools developed and the results obtained in this work are directly relevant to present-day ultracold-atom experiments based on shaken optical lattices and are expected to provide an insightful guidance in the quest for Floquet engineering.

  12. Parametric vs. non-parametric daily weather generator: validation and comparison

    NASA Astrophysics Data System (ADS)

    Dubrovsky, Martin

    2016-04-01

    As the climate models (GCMs and RCMs) fail to satisfactorily reproduce the real-world surface weather regime, various statistical methods are applied to downscale GCM/RCM outputs into site-specific weather series. The stochastic weather generators are among the most favourite downscaling methods capable to produce realistic (observed like) meteorological inputs for agrological, hydrological and other impact models used in assessing sensitivity of various ecosystems to climate change/variability. To name their advantages, the generators may (i) produce arbitrarily long multi-variate synthetic weather series representing both present and changed climates (in the latter case, the generators are commonly modified by GCM/RCM-based climate change scenarios), (ii) be run in various time steps and for multiple weather variables (the generators reproduce the correlations among variables), (iii) be interpolated (and run also for sites where no weather data are available to calibrate the generator). This contribution will compare two stochastic daily weather generators in terms of their ability to reproduce various features of the daily weather series. M&Rfi is a parametric generator: Markov chain model is used to model precipitation occurrence, precipitation amount is modelled by the Gamma distribution, and the 1st order autoregressive model is used to generate non-precipitation surface weather variables. The non-parametric GoMeZ generator is based on the nearest neighbours resampling technique making no assumption on the distribution of the variables being generated. Various settings of both weather generators will be assumed in the present validation tests. The generators will be validated in terms of (a) extreme temperature and precipitation characteristics (annual and 30 years extremes and maxima of duration of hot/cold/dry/wet spells); (b) selected validation statistics developed within the frame of VALUE project. The tests will be based on observational weather series

  13. Algorithm for parametric community detection in networks.

    PubMed

    Bettinelli, Andrea; Hansen, Pierre; Liberti, Leo

    2012-07-01

    Modularity maximization is extensively used to detect communities in complex networks. It has been shown, however, that this method suffers from a resolution limit: Small communities may be undetectable in the presence of larger ones even if they are very dense. To alleviate this defect, various modifications of the modularity function have been proposed as well as multiresolution methods. In this paper we systematically study a simple model (proposed by Pons and Latapy [Theor. Comput. Sci. 412, 892 (2011)] and similar to the parametric model of Reichardt and Bornholdt [Phys. Rev. E 74, 016110 (2006)]) with a single parameter α that balances the fraction of within community edges and the expected fraction of edges according to the configuration model. An exact algorithm is proposed to find optimal solutions for all values of α as well as the corresponding successive intervals of α values for which they are optimal. This algorithm relies upon a routine for exact modularity maximization and is limited to moderate size instances. An agglomerative hierarchical heuristic is therefore proposed to address parametric modularity detection in large networks. At each iteration the smallest value of α for which it is worthwhile to merge two communities of the current partition is found. Then merging is performed and the data are updated accordingly. An implementation is proposed with the same time and space complexity as the well-known Clauset-Newman-Moore (CNM) heuristic [Phys. Rev. E 70, 066111 (2004)]. Experimental results on artificial and real world problems show that (i) communities are detected by both exact and heuristic methods for all values of the parameter α; (ii) the dendrogram summarizing the results of the heuristic method provides a useful tool for substantive analysis, as illustrated particularly on a Les Misérables data set; (iii) the difference between the parametric modularity values given by the exact method and those given by the heuristic is

  14. Mapping the Chevallier-Polarski-Linder parametrization onto physical dark energy Models

    NASA Astrophysics Data System (ADS)

    Scherrer, Robert J.

    2015-08-01

    We examine the Chevallier-Polarski-Linder (CPL) parametrization, in the context of quintessence and barotropic dark energy models, to determine the subset of such models to which it can provide a good fit. The CPL parametrization gives the equation of state parameter w for the dark energy as a linear function of the scale factor a , namely w =w0+wa(1 -a ). In the case of quintessence models, we find that over most of the w0, wa parameter space the CPL parametrization maps onto a fairly narrow form of behavior for the potential V (ϕ ), while a one-dimensional subset of parameter space, for which wa=κ (1 +w0) , with κ constant, corresponds to a wide range of functional forms for V (ϕ ). For barotropic models, we show that the functional dependence of the pressure on the density, up to a multiplicative constant, depends only on wi=wa+w0 and not on w0 and wa separately. Our results suggest that the CPL parametrization may not be optimal for testing either type of model.

  15. Development of an acoustic filter for parametric loudspeaker using phononic crystals.

    PubMed

    Ji, Peifeng; Hu, Wenlin; Yang, Jun

    2016-04-01

    The spurious signal generated as a result of nonlinearity at the receiving system affects the measurement of the difference-frequency sound in the parametric loudspeaker, especially in the nearfield or near the beam axis. In this paper, an acoustic filter is designed using phononic crystals and its theoretical simulations are carried out by quasi-one- and two-dimensional models with Comsol Multiphysics. According to the simulated transmission loss (TL), an acoustic filter is prototyped consisting of 5×7 aluminum alloy cylinders and its performance is verified experimentally. There is good agreement with the simulation result for TL. After applying our proposed filter in the axial measurement of the parametric loudspeaker, a clear frequency dependence from parametric array effect is detected, which exhibits a good match with the well-known theory described by the Gaussian-beam expansion technique. During the directivity measurement for the parametric loudspeaker, the proposed filter has also proved to be effective and is only needed for small angles. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. A micro-machined source transducer for a parametric array in air.

    PubMed

    Lee, Haksue; Kang, Daesil; Moon, Wonkyu

    2009-04-01

    Parametric array applications in air, such as highly directional parametric loudspeaker systems, usually rely on large radiators to generate the high-intensity primary beams required for nonlinear interactions. However, a conventional transducer, as a primary wave projector, requires a great deal of electrical power because its electroacoustic efficiency is very low due to the large characteristic mechanical impedance in air. The feasibility of a micro-machined ultrasonic transducer as an efficient finite-amplitude wave projector was studied. A piezoelectric micro-machined ultrasonic transducer array consisting of lead zirconate titanate uni-morph elements was designed and fabricated for this purpose. Theoretical and experimental evaluations showed that a micro-machined ultrasonic transducer array can be used as an efficient source transducer for a parametric array in air. The beam patterns and propagation curves of the difference frequency wave and the primary wave generated by the micro-machined ultrasonic transducer array were measured. Although the theoretical results were based on ideal parametric array models, the theoretical data explained the experimental results reasonably well. These experiments demonstrated the potential of micro-machined primary wave projector.

  17. A multimode electromechanical parametric resonator array

    PubMed Central

    Mahboob, I.; Mounaix, M.; Nishiguchi, K.; Fujiwara, A.; Yamaguchi, H.

    2014-01-01

    Electromechanical resonators have emerged as a versatile platform in which detectors with unprecedented sensitivities and quantum mechanics in a macroscopic context can be developed. These schemes invariably utilise a single resonator but increasingly the concept of an array of electromechanical resonators is promising a wealth of new possibilities. In spite of this, experimental realisations of such arrays have remained scarce due to the formidable challenges involved in their fabrication. In a variation to this approach, we identify 75 harmonic vibration modes in a single electromechanical resonator of which 7 can also be parametrically excited. The parametrically resonating modes exhibit vibrations with only 2 oscillation phases which are used to build a binary information array. We exploit this array to execute a mechanical byte memory, a shift-register and a controlled-NOT gate thus vividly illustrating the availability and functionality of an electromechanical resonator array by simply utilising higher order vibration modes. PMID:24658349

  18. Parametric Imaging Of Digital Subtraction Angiography Studies For Renal Transplant Evaluation

    NASA Astrophysics Data System (ADS)

    Gallagher, Joe H.; Meaney, Thomas F.; Flechner, Stuart M.; Novick, Andrew C.; Buonocore, Edward

    1981-11-01

    A noninvasive method for diagnosing acute tubular necrosis and rejection would be an important tool for the management of renal transplant patients. From a sequence of digital subtraction angiographic images acquired after an intravenous injection of radiographic contrast material, the parametric images of the maximum contrast, the time when the maximum contrast is reached, and two times the time at which one half of the maximum contrast is reached are computed. The parametric images of the time when the maximum is reached clearly distinguish normal from abnormal renal function. However, it is the parametric image of two times the time when one half of the maximum is reached which provides some assistance in differentiating acute tubular necrosis from rejection.

  19. Oncology Nurse Generalist Competencies: Oncology Nursing Society's Initiative to Establish Best Practice.

    PubMed

    Gaguski, Michele E; George, Kim; Bruce, Susan D; Brucker, Edie; Leija, Carol; LeFebvre, Kristine B; Mackey, Heather

    2017-12-01

    A project team was formulated to create evidence-based oncology nurse generalist competencies (ONGCs) to establish best practices in competency development, including high-risk tasks, critical thinking criteria, and measurement of key areas for oncology nurses.
. This article aims to describe the process and the development of ONGCs. 
. This article explains how the ONGCs were accomplished, and includes outcomes and suggestions for use in clinical practice. 
. Institutions can use the ONGCs to assess and develop competency programs, offer educational strategies to measure proficiency, and establish processes to foster a workplace committed to mentoring and teaching future oncology nurses.

  20. 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)

  1. Impact Response Comparison Between Parametric Human Models and Postmortem Human Subjects with a Wide Range of Obesity Levels.

    PubMed

    Zhang, Kai; Cao, Libo; Wang, Yulong; Hwang, Eunjoo; Reed, Matthew P; Forman, Jason; Hu, Jingwen

    2017-10-01

    Field data analyses have shown that obesity significantly increases the occupant injury risks in motor vehicle crashes, but the injury assessment tools for people with obesity are largely lacking. The objectives of this study were to use a mesh morphing method to rapidly generate parametric finite element models with a wide range of obesity levels and to evaluate their biofidelity against impact tests using postmortem human subjects (PMHS). Frontal crash tests using three PMHS seated in a vehicle rear seat compartment with body mass index (BMI) from 24 to 40 kg/m 2 were selected. To develop the human models matching the PMHS geometry, statistical models of external body shape, rib cage, pelvis, and femur were applied to predict the target geometry using age, sex, stature, and BMI. A mesh morphing method based on radial basis functions was used to rapidly morph a baseline human model into the target geometry. The model-predicted body excursions and injury measures were compared to the PMHS tests. Comparisons of occupant kinematics and injury measures between the tests and simulations showed reasonable correlations across the wide range of BMI levels. The parametric human models have the capability to account for the obesity effects on the occupant impact responses and injury risks. © 2017 The Obesity Society.

  2. Sudden Death in Heart Failure With Preserved Ejection Fraction: A Competing Risks Analysis From the TOPCAT Trial.

    PubMed

    Vaduganathan, Muthiah; Claggett, Brian L; Chatterjee, Neal A; Anand, Inder S; Sweitzer, Nancy K; Fang, James C; O'Meara, Eileen; Shah, Sanjiv J; Hegde, Sheila M; Desai, Akshay S; Lewis, Eldrin F; Rouleau, Jean; Pitt, Bertram; Pfeffer, Marc A; Solomon, Scott D

    2018-03-04

    This study investigated the rates and predictors of SD or aborted cardiac arrest (ACA) in HFpEF. Sudden death (SD) may be an important mode of death in heart failure with preserved ejection fraction (HFpEF). We studied 1,767 patients with HFpEF (EF ≥45%) enrolled in the Americas region of the TOPCAT (Aldosterone Antagonist Therapy for Adults With Heart Failure and Preserved Systolic Function) trial. We identified independent predictors of composite SD/ACA with stepwise backward selection using competing risks regression analysis that accounted for nonsudden causes of death. During a median 3.0-year (25 th to 75 th percentile: 1.9 to 4.4 years) follow-up, 77 patients experienced SD/ACA, and 312 experienced non-SD/ACA. Corresponding incidence rates were 1.4 events/100 patient-years (25 th to 75 th percentile: 1.1 to 1.8 events/100 patient-years) and 5.8 events/100 patient-years (25 th to 75 th percentile: 5.1 to 6.4 events/100 patient-years). SD/ACA was numerically lower but not statistically reduced in those randomized to spironolactone: 1.2 events/100 patient-years (25 th to 75 th percentile: 0.9 to 1.7 events/100 patient-years) versus 1.6 events/100 patient-years (25 th to 75 th percentile: 1.2 to 2.2 events/100 patient-years); the subdistributional hazard ratio was 0.74 (95% confidence interval: 0.47 to 1.16; p = 0.19). After accounting for competing risks of non-SD/ACA, male sex and insulin-treated diabetes mellitus were independently predictive of composite SD/ACA (C-statistic = 0.65). Covariates, including eligibility criteria, age, ejection fraction, coronary artery disease, left bundle branch block, and baseline therapies, were not independently associated with SD/ACA. Sex and diabetes mellitus status remained independent predictors in sensitivity analyses, excluding patients with implantable cardioverter-defibrillators and when predicting SD alone. SD accounted for ∼20% of deaths in HFpEF. Male sex and insulin-treated diabetes mellitus identified

  3. Parametric amplification of a superconducting plasma wave

    DOE PAGES

    Rajasekaran, S.; Casandruc, E.; Laplace, Y.; ...

    2016-07-11

    Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor–metal oscillations and soliton formation. In this paper, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Finally, parametric amplification is sensitivemore » to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.« less

  4. Parametric spatiotemporal oscillation in reaction-diffusion systems

    NASA Astrophysics Data System (ADS)

    Ghosh, Shyamolina; Ray, Deb Shankar

    2016-03-01

    We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions.

  5. Parametric spatiotemporal oscillation in reaction-diffusion systems.

    PubMed

    Ghosh, Shyamolina; Ray, Deb Shankar

    2016-03-01

    We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions.

  6. 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.

  7. A Parametric Approach to Numerical Modeling of TKR Contact Forces

    PubMed Central

    Lundberg, Hannah J.; Foucher, Kharma C.; Wimmer, Markus A.

    2009-01-01

    In vivo knee contact forces are difficult to determine using numerical methods because there are more unknown forces than equilibrium equations available. We developed parametric methods for computing contact forces across the knee joint during the stance phase of level walking. Three-dimensional contact forces were calculated at two points of contact between the tibia and the femur, one on the lateral aspect of the tibial plateau, and one on the medial side. Muscle activations were parametrically varied over their physiologic range resulting in a solution space of contact forces. The obtained solution space was reasonably small and the resulting force pattern compared well to a previous model from the literature for kinematics and external kinetics from the same patient. Peak forces of the parametric model and the previous model were similar for the first half of the stance phase, but differed for the second half. The previous model did not take into account the transverse external moment about the knee and could not calculate muscle activation levels. Ultimately, the parametric model will result in more accurate contact force inputs for total knee simulators, as current inputs are not generally based on kinematics and kinetics inputs from TKR patients. PMID:19155015

  8. Key factors in children's competence to consent to clinical research.

    PubMed

    Hein, Irma M; Troost, Pieter W; Lindeboom, Robert; Benninga, Marc A; Zwaan, C Michel; van Goudoever, Johannes B; Lindauer, Ramón J L

    2015-10-24

    Although law is established on a strong presumption that persons younger than a certain age are not competent to consent, statutory age limits for asking children's consent to clinical research differ widely internationally. From a clinical perspective, competence is assumed to involve many factors including the developmental stage, the influence of parents and peers, and life experience. We examined potential determining factors for children's competence to consent to clinical research and to what extent they explain the variation in competence judgments. From January 1, 2012 through January 1, 2014, pediatric patients aged 6 to 18 years, eligible for clinical research studies were enrolled prospectively at various in- and outpatient pediatric departments. Children's competence to consent was assessed by MacArthur Competence Assessment Tool for Clinical Research. Potential determining child variables included age, gender, intelligence, disease experience, ethnicity and socio-economic status (SES). We used logistic regression analysis and change in explained variance in competence judgments to quantify the contribution of a child variable to the total explained variance. Contextual factors included risk and complexity of the decision to participate, parental competence judgment and the child's or parents decision to participate. Out of 209 eligible patients, 161 were included (mean age, 10.6 years, 47.2 % male). Age, SES, intelligence, ethnicity, complexity, parental competence judgment and trial participation were univariately associated with competence (P < 0.05). Total explained variance in competence judgments was 71.5 %. Only age and intelligence significantly and independently explained the variance in competence judgments, explaining 56.6 % and 12.7 % of the total variance respectively. SES, male gender, disease experience and ethnicity each explained less than 1 % of the variance in competence judgments. Contextual factors together explained an extra 2

  9. Competence, competency-based education, and undergraduate dental education: a discussion paper.

    PubMed

    Chuenjitwongsa, S; Oliver, R G; Bullock, A D

    2018-02-01

    The aim of undergraduate dental education is to provide competent dentists to serve societal needs and improve population oral healthcare. Competency-based education has influenced the development of dental education for decades but this term is problematic. This article explores components of competency-based undergraduate health professional education in order to help the dental profession have a better understanding of the context and purposes of undergraduate dental education. This is a discussion paper based on a wide reading of the literature on the education of health professionals with a specific focus on competency-based undergraduate education. Competence comprises an integration of knowledge, skills and attitudes indicating a capability to perform professional tasks safely and ethically. The process of becoming a competent practitioner is complex. Four characteristics of competency-based education are: curriculum components and content shaped by societal needs; focused on student-centred learning; learning achievement; and limited attention to time-based training and numerical targets. Alongside a competency-based approach, undergraduate dental education can be influenced by institutional features and external factors but these receive little consideration in the literature. Understanding competence, competency-based education, and institutional and external factors will help to improve educational quality, define roles and professional development for the dental educator, and inform further research. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. [The use of operational criteria for evaluations of mental competency].

    PubMed

    Kocha, Hiroki

    2013-01-01

    Today, either the DSM-IV or the ICD-10 is generally used for forensic purposes, especially for evaluations of mental competency. The use of operational criteria, such as the DSM-IV, in forensic settings has some risks. Here, these risks, as well as the advantages of operational criteria and precautions for their use, are discussed. Compared with the DSM-IV, the ICD-10 is preferred because this tool is less likely to complicate evaluations of the mental status of a criminal at the time of the crime when sufficient information is not available to make a diagnosis. The evaluation consists of two steps. The first step, which is based on empirical science, is to provide a psychiatric diagnosis. The second step, which is based on normative science, is to allocate the diagnosis to one of four categories of a forensic frame of reference and to provide useful information for judicial members to make a judgment about the mental competency of the criminal. To standardize evaluations, the use of not only global standard criteria, but also a general rule for the judgment of mental competency within each allocated category is needed.

  11. Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar.

    PubMed

    Foote, Kenneth G

    2012-05-01

    Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1-6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.

  12. Parametrically Guided Generalized Additive Models with Application to Mergers and Acquisitions Data.

    PubMed

    Fan, Jianqing; Maity, Arnab; Wang, Yihui; Wu, Yichao

    2013-01-01

    Generalized nonparametric additive models present a flexible way to evaluate the effects of several covariates on a general outcome of interest via a link function. In this modeling framework, one assumes that the effect of each of the covariates is nonparametric and additive. However, in practice, often there is prior information available about the shape of the regression functions, possibly from pilot studies or exploratory analysis. In this paper, we consider such situations and propose an estimation procedure where the prior information is used as a parametric guide to fit the additive model. Specifically, we first posit a parametric family for each of the regression functions using the prior information (parametric guides). After removing these parametric trends, we then estimate the remainder of the nonparametric functions using a nonparametric generalized additive model, and form the final estimates by adding back the parametric trend. We investigate the asymptotic properties of the estimates and show that when a good guide is chosen, the asymptotic variance of the estimates can be reduced significantly while keeping the asymptotic variance same as the unguided estimator. We observe the performance of our method via a simulation study and demonstrate our method by applying to a real data set on mergers and acquisitions.

  13. Parametrically Guided Generalized Additive Models with Application to Mergers and Acquisitions Data

    PubMed Central

    Fan, Jianqing; Maity, Arnab; Wang, Yihui; Wu, Yichao

    2012-01-01

    Generalized nonparametric additive models present a flexible way to evaluate the effects of several covariates on a general outcome of interest via a link function. In this modeling framework, one assumes that the effect of each of the covariates is nonparametric and additive. However, in practice, often there is prior information available about the shape of the regression functions, possibly from pilot studies or exploratory analysis. In this paper, we consider such situations and propose an estimation procedure where the prior information is used as a parametric guide to fit the additive model. Specifically, we first posit a parametric family for each of the regression functions using the prior information (parametric guides). After removing these parametric trends, we then estimate the remainder of the nonparametric functions using a nonparametric generalized additive model, and form the final estimates by adding back the parametric trend. We investigate the asymptotic properties of the estimates and show that when a good guide is chosen, the asymptotic variance of the estimates can be reduced significantly while keeping the asymptotic variance same as the unguided estimator. We observe the performance of our method via a simulation study and demonstrate our method by applying to a real data set on mergers and acquisitions. PMID:23645976

  14. Nonparametric estimation of benchmark doses in environmental risk assessment

    PubMed Central

    Piegorsch, Walter W.; Xiong, Hui; Bhattacharya, Rabi N.; Lin, Lizhen

    2013-01-01

    Summary An important statistical objective in environmental risk analysis is estimation of minimum exposure levels, called benchmark doses (BMDs), that induce a pre-specified benchmark response in a dose-response experiment. In such settings, representations of the risk are traditionally based on a parametric dose-response model. It is a well-known concern, however, that if the chosen parametric form is misspecified, inaccurate and possibly unsafe low-dose inferences can result. We apply a nonparametric approach for calculating benchmark doses, based on an isotonic regression method for dose-response estimation with quantal-response data (Bhattacharya and Kong, 2007). We determine the large-sample properties of the estimator, develop bootstrap-based confidence limits on the BMDs, and explore the confidence limits’ small-sample properties via a short simulation study. An example from cancer risk assessment illustrates the calculations. PMID:23914133

  15. A generalized parametric response mapping method for analysis of multi-parametric imaging: A feasibility study with application to glioblastoma.

    PubMed

    Lausch, Anthony; Yeung, Timothy Pok-Chi; Chen, Jeff; Law, Elton; Wang, Yong; Urbini, Benedetta; Donelli, Filippo; Manco, Luigi; Fainardi, Enrico; Lee, Ting-Yim; Wong, Eugene

    2017-11-01

    Parametric response map (PRM) analysis of functional imaging has been shown to be an effective tool for early prediction of cancer treatment outcomes and may also be well-suited toward guiding personalized adaptive radiotherapy (RT) strategies such as sub-volume boosting. However, the PRM method was primarily designed for analysis of longitudinally acquired pairs of single-parameter image data. The purpose of this study was to demonstrate the feasibility of a generalized parametric response map analysis framework, which enables analysis of multi-parametric data while maintaining the key advantages of the original PRM method. MRI-derived apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) maps acquired at 1 and 3-months post-RT for 19 patients with high-grade glioma were used to demonstrate the algorithm. Images were first co-registered and then standardized using normal tissue image intensity values. Tumor voxels were then plotted in a four-dimensional Cartesian space with coordinate values equal to a voxel's image intensity in each of the image volumes and an origin defined as the multi-parametric mean of normal tissue image intensity values. Voxel positions were orthogonally projected onto a line defined by the origin and a pre-determined response vector. The voxels are subsequently classified as positive, negative or nil, according to whether projected positions along the response vector exceeded a threshold distance from the origin. The response vector was selected by identifying the direction in which the standard deviation of tumor image intensity values was maximally different between responding and non-responding patients within a training dataset. Voxel classifications were visualized via familiar three-class response maps and then the fraction of tumor voxels associated with each of the classes was investigated for predictive utility analogous to the original PRM method. Independent PRM and MPRM analyses of the contrast

  16. The development of a competency framework for pharmacists providing cancer services.

    PubMed

    Carrington, Christine; Weir, Janet; Smith, Peter

    2011-09-01

    Health practitioners should possess relevant, up to date skills and be able to perform within their required scope of practice to ensure that they are competent. Maintaining the competency of health care professionals is a key principle of clinical governance and risk management. The aim of this project was to develop a competency framework for pharmacists providing pharmaceutical care to cancer patients. An initial draft framework was developed based on existing documentation and adapted to the needs of Queensland Health (QH) facilities. Pharmacists in QH and interstate were asked to review the framework for content and applicability. Cancer care pharmacists in QH were invited to evaluate and score the usefulness and relevance of the final framework. The framework consists of competency clusters, which describe core activities within three areas: patient care competencies, knowledge competencies, and advanced level competencies. The characteristics of the levels of practice at foundation, advanced, and consultant are defined. Twelve pharmacists evaluated the framework by self-assessing their own practice. Respondents reported that the framework was very to somewhat reflective of what they usually do and gave overall support for the content and applicability to practice. The framework has been developed using national and international documents and the input of experienced practitioners across Australia. It represents a set of key competencies for the pharmaceutical delivery of cancer care. The next essential step of the competency framework is to implement and integrate the framework into practice and to develop accompanying training tools.

  17. [Construction of the addiction prevention core competency model for preventing addictive behavior in adolescents].

    PubMed

    Park, Hyun Sook; Jung, Sun Young

    2013-12-01

    This study was done to provide fundamental data for the development of competency reinforcement programs to prevent addictive behavior in adolescents through the construction and examination of an addiction prevention core competency model. In this study core competencies for preventing addictive behavior in adolescents through competency modeling were identified, and the addiction prevention core competency model was developed. It was validated methodologically. Competencies for preventing addictive behavior in adolescents as defined by the addiction prevention core competency model are as follows: positive self-worth, self-control skill, time management skill, reality perception skill, risk coping skill, and positive communication with parents and with peers or social group. After construction, concurrent cross validation of the addiction prevention core competency model showed that this model was appropriate. The study results indicate that the addiction prevention core competency model for the prevention of addictive behavior in adolescents through competency modeling can be used as a foundation for an integral approach to enhance adolescent is used as an adjective and prevent addictive behavior. This approach can be a school-centered, cost-efficient strategy which not only reduces addictive behavior in adolescents, but also improves the quality of their resources.

  18. Management mechanisms for development of personnel professional competencies at a loading and haulage company

    NASA Astrophysics Data System (ADS)

    Shishkina, S. V.; Pristupa, Yu D.; Pavlova, L. D.; Fryanov, V. N.

    2018-05-01

    The necessity for development a management mechanism for development of personnel professional competencies at a loading and haulage company in order to ensuring the compliance of competencies with labor functions, regulated by the current professional standards, is substantiated. A functional diagram of the organizational and technical system of the loading and haulage company was developed, that includes the interaction mechanism between the personnel and the objects of the main production. The problem of algorithm development to assess the correspondence of communicative competencies and labor functions of loading and haulage companies, ensuring the achievement of the management goal with a minimum risk of an emergency situation or an accident, was set and solved. The idea of management problem solving consists in the operational development and implementation of anticipatory measures at each deviation in personnel actions from normative or target indicators. The dependence of the risk of imbalance of communicative competences and labor functions in a given period of time is established. The effectiveness of the developed and implemented mechanism is confirmed by the positive dynamics of the test results.

  19. Changing space and sound: Parametric design and variable acoustics

    NASA Astrophysics Data System (ADS)

    Norton, Christopher William

    This thesis examines the potential for parametric design software to create performance based design using acoustic metrics as the design criteria. A former soundstage at the University of Southern California used by the Thornton School of Music is used as a case study for a multiuse space for orchestral, percussion, master class and recital use. The criteria used for each programmatic use include reverberation time, bass ratio, and the early energy ratios of the clarity index and objective support. Using a panelized ceiling as a design element to vary the parameters of volume, panel orientation and type of absorptive material, the relationships between these parameters and the design criteria are explored. These relationships and subsequently derived equations are applied to Grasshopper parametric modeling software for Rhino 3D (a NURBS modeling software). Using the target reverberation time and bass ratio for each programmatic use as input for the parametric model, the genomic optimization function of Grasshopper - Galapagos - is run to identify the optimum ceiling geometry and material distribution.

  20. Definition of NASTRAN sets by use of parametric geometry

    NASA Technical Reports Server (NTRS)

    Baughn, Terry V.; Tiv, Mehran

    1989-01-01

    Many finite element preprocessors describe finite element model geometry with points, lines, surfaces and volumes. One method for describing these basic geometric entities is by use of parametric cubics which are useful for representing complex shapes. The lines, surfaces and volumes may be discretized for follow on finite element analysis. The ability to limit or selectively recover results from the finite element model is extremely important to the analyst. Equally important is the ability to easily apply boundary conditions. Although graphical preprocessors have made these tasks easier, model complexity may not lend itself to easily identify a group of grid points desired for data recovery or application of constraints. A methodology is presented which makes use of the assignment of grid point locations in parametric coordinates. The parametric coordinates provide a convenient ordering of the grid point locations and a method for retrieving the grid point ID's from the parent geometry. The selected grid points may then be used for the generation of the appropriate set and constraint cards.

  1. The Interrelations between Competences for Sustainable Development and Research Competences

    ERIC Educational Resources Information Center

    Lambrechts, Wim; Van Petegem, Peter

    2016-01-01

    Purpose: The purpose of this paper is to explore how competences for sustainable development and research interrelate within a context of competence-based higher education. Specific focus is oriented towards strengthening research competences for sustainability. Design/methodology/approach: Following a hermeneutic-interpretive methodology, this…

  2. 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.

  3. Parametric excitation and squeezing in a many-body spinor condensate

    PubMed Central

    Hoang, T. M.; Anquez, M.; Robbins, B. A.; Yang, X. Y.; Land, B. J.; Hamley, C. D.; Chapman, M. S.

    2016-01-01

    Atomic spins are usually manipulated using radio frequency or microwave fields to excite Rabi oscillations between different spin states. These are single-particle quantum control techniques that perform ideally with individual particles or non-interacting ensembles. In many-body systems, inter-particle interactions are unavoidable; however, interactions can be used to realize new control schemes unique to interacting systems. Here we demonstrate a many-body control scheme to coherently excite and control the quantum spin states of an atomic Bose gas that realizes parametric excitation of many-body collective spin states by time varying the relative strength of the Zeeman and spin-dependent collisional interaction energies at multiples of the natural frequency of the system. Although parametric excitation of a classical system is ineffective from the ground state, we show that in our experiment, parametric excitation from the quantum ground state leads to the generation of quantum squeezed states. PMID:27044675

  4. Parametric excitation and squeezing in a many-body spinor condensate

    NASA Astrophysics Data System (ADS)

    Hoang, T. M.; Anquez, M.; Robbins, B. A.; Yang, X. Y.; Land, B. J.; Hamley, C. D.; Chapman, M. S.

    2016-04-01

    Atomic spins are usually manipulated using radio frequency or microwave fields to excite Rabi oscillations between different spin states. These are single-particle quantum control techniques that perform ideally with individual particles or non-interacting ensembles. In many-body systems, inter-particle interactions are unavoidable; however, interactions can be used to realize new control schemes unique to interacting systems. Here we demonstrate a many-body control scheme to coherently excite and control the quantum spin states of an atomic Bose gas that realizes parametric excitation of many-body collective spin states by time varying the relative strength of the Zeeman and spin-dependent collisional interaction energies at multiples of the natural frequency of the system. Although parametric excitation of a classical system is ineffective from the ground state, we show that in our experiment, parametric excitation from the quantum ground state leads to the generation of quantum squeezed states.

  5. Realization of an omnidirectional source of sound using parametric loudspeakers.

    PubMed

    Sayin, Umut; Artís, Pere; Guasch, Oriol

    2013-09-01

    Parametric loudspeakers are often used in beam forming applications where a high directivity is required. Withal, in this paper it is proposed to use such devices to build an omnidirectional source of sound. An initial prototype, the omnidirectional parametric loudspeaker (OPL), consisting of a sphere with hundreds of ultrasonic transducers placed on it has been constructed. The OPL emits audible sound thanks to the parametric acoustic array phenomenon, and the close proximity and the large number of transducers results in the generation of a highly omnidirectional sound field. Comparisons with conventional dodecahedron loudspeakers have been made in terms of directivity, frequency response, and in applications such as the generation of diffuse acoustic fields in reverberant chambers. The OPL prototype has performed better than the conventional loudspeaker especially for frequencies higher than 500 Hz, its main drawback being the difficulty to generate intense pressure levels at low frequencies.

  6. 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. © 2014, The International Biometric Society.

  7. Bim and Gis: when Parametric Modeling Meets Geospatial Data

    NASA Astrophysics Data System (ADS)

    Barazzetti, L.; Banfi, F.

    2017-12-01

    Geospatial data have a crucial role in several projects related to infrastructures and land management. GIS software are able to perform advanced geospatial analyses, but they lack several instruments and tools for parametric modelling typically available in BIM. At the same time, BIM software designed for buildings have limited tools to handle geospatial data. As things stand at the moment, BIM and GIS could appear as complementary solutions, notwithstanding research work is currently under development to ensure a better level of interoperability, especially at the scale of the building. On the other hand, the transition from the local (building) scale to the infrastructure (where geospatial data cannot be neglected) has already demonstrated that parametric modelling integrated with geoinformation is a powerful tool to simplify and speed up some phases of the design workflow. This paper reviews such mixed approaches with both simulated and real examples, demonstrating that integration is already a reality at specific scales, which are not dominated by "pure" GIS or BIM. The paper will also demonstrate that some traditional operations carried out with GIS software are also available in parametric modelling software for BIM, such as transformation between reference systems, DEM generation, feature extraction, and geospatial queries. A real case study is illustrated and discussed to show the advantage of a combined use of both technologies. BIM and GIS integration can generate greater usage of geospatial data in the AECOO (Architecture, Engineering, Construction, Owner and Operator) industry, as well as new solutions for parametric modelling with additional geoinformation.

  8. A numerical study on piezoelectric energy harvesting by combining transverse galloping and parametric instability phenomena

    NASA Astrophysics Data System (ADS)

    Franzini, Guilherme Rosa; Santos, Rebeca Caramêz Saraiva; Pesce, Celso Pupo

    2017-12-01

    This paper aims to numerically investigate the effects of parametric instability on piezoelectric energy harvesting from the transverse galloping of a square prism. A two degrees-of-freedom reduced-order model for this problem is proposed and numerically integrated. A usual quasi-steady galloping model is applied, where the transverse force coefficient is adopted as a cubic polynomial function with respect to the angle of attack. Time-histories of nondimensional prism displacement, electric voltage and power dissipated at both the dashpot and the electrical resistance are obtained as functions of the reduced velocity. Both, oscillation amplitude and electric voltage, increased with the reduced velocity for all parametric excitation conditions tested. For low values of reduced velocity, 2:1 parametric excitation enhances the electric voltage. On the other hand, for higher reduced velocities, a 1:1 parametric excitation (i.e., the same as the natural frequency) enhances both oscillation amplitude and electric voltage. It has been also found that, depending on the parametric excitation frequency, the harvested electrical power can be amplified in 70% when compared to the case under no parametric excitation.

  9. Multi-Watt femtosecond optical parametric master oscillator power amplifier at 43 MHz.

    PubMed

    Mörz, Florian; Steinle, Tobias; Steinmann, Andy; Giessen, Harald

    2015-09-07

    We present a high repetition rate mid-infrared optical parametric master oscillator power amplifier (MOPA) scheme, which is tunable from 1370 to 4120nm. Up to 4.3W average output power are generated at 1370nm, corresponding to a photon conversion efficiency of 78%. Bandwidths of 6 to 12nm with pulse durations between 250 and 400fs have been measured. Strong conversion saturation over the whole signal range is observed, resulting in excellent power stability. The system consists of a fiber-feedback optical parametric oscillator that seeds an optical parametric power amplifier. Both systems are pumped by the same Yb:KGW femtosecond oscillator.

  10. 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.

  11. Establishment of Biological Reference Intervals and Reference Curve for Urea by Exploratory Parametric and Non-Parametric Quantile Regression Models.

    PubMed

    Sarkar, Rajarshi

    2013-07-01

    The validity of the entire renal function tests as a diagnostic tool depends substantially on the Biological Reference Interval (BRI) of urea. Establishment of BRI of urea is difficult partly because exclusion criteria for selection of reference data are quite rigid and partly due to the compartmentalization considerations regarding age and sex of the reference individuals. Moreover, construction of Biological Reference Curve (BRC) of urea is imperative to highlight the partitioning requirements. This a priori study examines the data collected by measuring serum urea of 3202 age and sex matched individuals, aged between 1 and 80 years, by a kinetic UV Urease/GLDH method on a Roche Cobas 6000 auto-analyzer. Mann-Whitney U test of the reference data confirmed the partitioning requirement by both age and sex. Further statistical analysis revealed the incompatibility of the data for a proposed parametric model. Hence the data was non-parametrically analysed. BRI was found to be identical for both sexes till the 2(nd) decade, and the BRI for males increased progressively 6(th) decade onwards. Four non-parametric models were postulated for construction of BRC: Gaussian kernel, double kernel, local mean and local constant, of which the last one generated the best-fitting curves. Clinical decision making should become easier and diagnostic implications of renal function tests should become more meaningful if this BRI is followed and the BRC is used as a desktop tool in conjunction with similar data for serum creatinine.

  12. Temporal-contrast measurements of a white-light-seeded noncollinear optical parametric amplifier

    DOE PAGES

    Bromage, J.; Dorrer, C.; Zuegel, J. D.

    2015-09-01

    Ultra-intense optical parametric chirped-pulse systems require front ends with broad bandwidth and high temporal contrast. Temporal cross-correlation measurements of a white-light–seeded noncollinear optical parametric amplifier (NOPA) show that its prepulse contrast exceeds the 120 dB dynamic range of the broadband NOPA-based cross-correlator.

  13. Nature, Nurture and Evolution of Intra-Species Variation in Mosquito Arbovirus Transmission Competence

    PubMed Central

    Tabachnick, Walter J.

    2013-01-01

    Mosquitoes vary in their competence or ability to transmit arthropod-borne viruses (arboviruses). Many arboviruses cause disease in humans and animals. Identifying the environmental and genetic causes of variation in mosquito competence for arboviruses is one of the great challenges in public health. Progress identifying genetic (nature) and environmental (nurture) factors influencing mosquito competence for arboviruses is reviewed. There is great complexity in the various traits that comprise mosquito competence. The complex interactions between environmental and genetic factors controlling these traits and the factors shaping variation in Nature are largely unknown. The norms of reaction of specific genes influencing competence, their distributions in natural populations and the effects of genetic polymorphism on phenotypic variation need to be determined. Mechanisms influencing competence are not likely due to natural selection because of the direct effects of the arbovirus on mosquito fitness. More likely the traits for mosquito competence for arboviruses are the effects of adaptations for other functions of these competence mechanisms. Determining these other functions is essential to understand the evolution and distributions of competence for arboviruses. This information is needed to assess risk from mosquito-borne disease, predict new mosquito-arbovirus systems, and provide novel strategies to mitigate mosquito-borne arbovirus transmission. PMID:23343982

  14. Nature, nurture and evolution of intra-species variation in mosquito arbovirus transmission competence.

    PubMed

    Tabachnick, Walter J

    2013-01-11

    Mosquitoes vary in their competence or ability to transmit arthropod-borne viruses (arboviruses). Many arboviruses cause disease in humans and animals. Identifying the environmental and genetic causes of variation in mosquito competence for arboviruses is one of the great challenges in public health. Progress identifying genetic (nature) and environmental (nurture) factors influencing mosquito competence for arboviruses is reviewed. There is great complexity in the various traits that comprise mosquito competence. The complex interactions between environmental and genetic factors controlling these traits and the factors shaping variation in Nature are largely unknown. The norms of reaction of specific genes influencing competence, their distributions in natural populations and the effects of genetic polymorphism on phenotypic variation need to be determined. Mechanisms influencing competence are not likely due to natural selection because of the direct effects of the arbovirus on mosquito fitness. More likely the traits for mosquito competence for arboviruses are the effects of adaptations for other functions of these competence mechanisms. Determining these other functions is essential to understand the evolution and distributions of competence for arboviruses. This information is needed to assess risk from mosquito-borne disease, predict new mosquito-arbovirus systems, and provide novel strategies to mitigate mosquito-borne arbovirus transmission.

  15. High-gain mid-infrared optical-parametric generation pumped by microchip laser.

    PubMed

    Ishizuki, Hideki; Taira, Takunori

    2016-01-25

    High-gain mid-infrared optical-parametric generation was demonstrated by simple single-pass configuration using PPMgLN devices pumped by giant-pulse microchip laser. Effective mid-infrared wavelength conversion with 1 mJ output energy from 2.4 mJ pumping using conventional PPMgLN could be realized. Broadband optical-parametric generation from 1.7 to 2.6 µm could be also measured using chirped PPMgLN.

  16. Assessment and Selection of Competing Models for Zero-Inflated Microbiome Data

    PubMed Central

    Xu, Lizhen; Paterson, Andrew D.; Turpin, Williams; Xu, Wei

    2015-01-01

    Typical data in a microbiome study consist of the operational taxonomic unit (OTU) counts that have the characteristic of excess zeros, which are often ignored by investigators. In this paper, we compare the performance of different competing methods to model data with zero inflated features through extensive simulations and application to a microbiome study. These methods include standard parametric and non-parametric models, hurdle models, and zero inflated models. We examine varying degrees of zero inflation, with or without dispersion in the count component, as well as different magnitude and direction of the covariate effect on structural zeros and the count components. We focus on the assessment of type I error, power to detect the overall covariate effect, measures of model fit, and bias and effectiveness of parameter estimations. We also evaluate the abilities of model selection strategies using Akaike information criterion (AIC) or Vuong test to identify the correct model. The simulation studies show that hurdle and zero inflated models have well controlled type I errors, higher power, better goodness of fit measures, and are more accurate and efficient in the parameter estimation. Besides that, the hurdle models have similar goodness of fit and parameter estimation for the count component as their corresponding zero inflated models. However, the estimation and interpretation of the parameters for the zero components differs, and hurdle models are more stable when structural zeros are absent. We then discuss the model selection strategy for zero inflated data and implement it in a gut microbiome study of > 400 independent subjects. PMID:26148172

  17. Assessment and Selection of Competing Models for Zero-Inflated Microbiome Data.

    PubMed

    Xu, Lizhen; Paterson, Andrew D; Turpin, Williams; Xu, Wei

    2015-01-01

    Typical data in a microbiome study consist of the operational taxonomic unit (OTU) counts that have the characteristic of excess zeros, which are often ignored by investigators. In this paper, we compare the performance of different competing methods to model data with zero inflated features through extensive simulations and application to a microbiome study. These methods include standard parametric and non-parametric models, hurdle models, and zero inflated models. We examine varying degrees of zero inflation, with or without dispersion in the count component, as well as different magnitude and direction of the covariate effect on structural zeros and the count components. We focus on the assessment of type I error, power to detect the overall covariate effect, measures of model fit, and bias and effectiveness of parameter estimations. We also evaluate the abilities of model selection strategies using Akaike information criterion (AIC) or Vuong test to identify the correct model. The simulation studies show that hurdle and zero inflated models have well controlled type I errors, higher power, better goodness of fit measures, and are more accurate and efficient in the parameter estimation. Besides that, the hurdle models have similar goodness of fit and parameter estimation for the count component as their corresponding zero inflated models. However, the estimation and interpretation of the parameters for the zero components differs, and hurdle models are more stable when structural zeros are absent. We then discuss the model selection strategy for zero inflated data and implement it in a gut microbiome study of > 400 independent subjects.

  18. Outcome of temporal lobe epilepsy surgery predicted by statistical parametric PET imaging.

    PubMed

    Wong, C Y; Geller, E B; Chen, E Q; MacIntyre, W J; Morris, H H; Raja, S; Saha, G B; Lüders, H O; Cook, S A; Go, R T

    1996-07-01

    PET is useful in the presurgical evaluation of temporal lobe epilepsy. The purpose of this retrospective study is to assess the clinical use of statistical parametric imaging in predicting surgical outcome. Interictal 18FDG-PET scans in 17 patients with surgically-treated temporal lobe epilepsy (Group A-13 seizure-free, group B = 4 not seizure-free at 6 mo) were transformed into statistical parametric imaging, with each pixel representing a z-score value by using the mean and s.d. of count distribution in each individual patient, for both visual and quantitative analysis. Mean z-scores were significantly more negative in anterolateral (AL) and mesial (M) regions on the operated side than the nonoperated side in group A (AL: p < 0.00005, M: p = 0.0097), but not in group B (AL: p = 0.46, M: p = 0.08). Statistical parametric imaging correctly lateralized 16 out of 17 patients. Only the AL region, however, was significant in predicting surgical outcome (F = 29.03, p < 0.00005). Using a cut-off z-score value of -1.5, statistical parametric imaging correctly classified 92% of temporal lobes from group A and 88% of those from Group B. The preliminary results indicate that statistical parametric imaging provides both clinically useful information for lateralization in temporal lobe epilepsy and a reliable predictive indicator of clinical outcome following surgical treatment.

  19. Measurement of IR optics with linear coupling's action-angle parametrization

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Bai, M.; Pilat, F.; Satogata, T.; Trbojevic, D.

    2005-08-01

    Linear coupling’s action-angle parametrization is convenient for interpretation of turn-by-turn beam position monitor (BPM) data. We demonstrate how to apply this parametrization to extract Twiss and coupling parameters in interaction regions (IRs), using BPMs on each side of a long IR drift region. Example data were acquired at the Relativistic Heavy Ion Collider, using an ac dipole to excite a single transverse eigenmode. We have measured the waist of the β function and its Twiss and coupling parameters.

  20. Is the Positive Illusory Bias Illusory? Examining Discrepant Self-Perceptions of Competence in Girls with ADHD

    ERIC Educational Resources Information Center

    Swanson, Erika N.; Owens, Elizabeth B.; Hinshaw, Stephen P.

    2012-01-01

    It has been claimed that excessively positive self-perceptions of competence are a key risk factor for concurrent and subsequent impairments in youth with attention-deficit/ hyperactivity disorder (ADHD). We examined whether girls with ADHD demonstrate positive illusory self-perceptions in scholastic competence, social acceptance, and behavioral…

  1. Athletic Coaching Competencies.

    ERIC Educational Resources Information Center

    Nathanson, Stephen J.

    1979-01-01

    This article describes a study conducted to identify the competencies appropriate for an athletic coach and to incorporate those competencies into a competency based coaching education program for the four-year colleges and universities within the New York state systems. (JMF)

  2. Physical Therapists' Ability to Identify Psychological Factors and Their Self-Reported Competence to Manage Chronic Low Back Pain.

    PubMed

    Brunner, Emanuel; Dankaerts, Wim; Meichtry, André; O'Sullivan, Kieran; Probst, Michel

    2018-06-01

    In the management of chronic low back pain (LBP), identifying and managing more patients who are at high risk and who have psychological barriers to recovery is important yet difficult. The objective of this study was to test physical therapists' ability to allocate patients into risk stratification groups, test correlations between therapists' assessments of psychological factors and patient questionnaires, and explore relationships between psychological factors and therapists' self-reported competence to manage patients with chronic LBP. This was a pragmatic, observational study. Patients completed the STarT Back Tool (SBT, for risk stratification), the Four-Dimensional Symptom Questionnaire (distress, depression, anxiety), and the Tampa Scale of Kinesiophobia (kinesiophobia) prior to the intake session. After this session, physical therapists estimated patient prognostic risk using the 3 SBT categories and rated patient psychological factors using a 0-to-10 scale. Finally, therapists reported their self-reported competence to manage the patient. Intraclass and Spearman rank correlations tested correlations between therapists' intuitive assessments and patient questionnaires. A linear-mixed model explored relationships between psychological factors and therapists' self-reported competence. Forty-nine patients were managed by 20 therapists. Therapists accurately estimated SBT risk allocation in only 41% of patients. Correlations between therapist perceptions and patient questionnaires were moderate for distress (r = 0.602) and fair for depression (r = 0.304) and anxiety (r = 0.327). There was no correlation for kinesiophobia (r = -0.007). Patient distress was identified as a negative predictor of therapists' self-reported competence. This was a cross-sectional study, conducted in only 1 center. Physical therapists were not very accurate at allocating patients into risk stratification groups or identifying psychological factors. Therapists' self

  3. Coaches’ Perceptions of Competence and Acknowledgement of Training Needs Related to Professional Competences

    PubMed Central

    Santos, Sofia; Mesquita, Isabel; GRAÇA, Amândio; Rosado, António

    2010-01-01

    The purpose of the present study was to examine coaches’ perceptions of competence and acknowledgement of training needs related to professional competences according to the professional experience and academic education. The participants were 343 coaches from several sports, who answered to a questionnaire that includes a scale focused on perceptions of competence and another scale on acknowledgment of training needs. An exploratory factor analysis with Maximum Likelihood Factoring was used with Oblimin rotation for the identification of emergent factors. Comparison on coaches’ perceptions in function of coaching experience and coaches’ academic background were made applying One-way ANOVA and Tukey’s post hoc multiple comparisons. Factor analysis on coaches’ perceptions of competence and acknowledgement of training needs made apparent three main areas of competences, i.e. competences related to annual and multi-annual planning; competences related to orientation towards practice and competition; and personal and coaching education competences. Coaches’ perceptions were influenced by their experience, as low experienced coaches rated themselves at lower levels of competence and with more training needs; also coaches with high education, in Physical Education or others, perceived themselves as more competent than coaches with no higher education. Finally, the majority of the coaches perceived themselves to be competent but, nevertheless, they indicated to have training needs, which brings an important feedback to coach education. This suggests that coaches are interested in increasing their knowledge and competence in a broad range of areas which should be considered in future coach education programs. Key points Coaches’ perceptions of competence and acknowledgement of training needs resulted in three main areas: competences related to annual and multi-annual planning, competences related to practice and competition orientation and, finally, personal

  4. Motor Skill Competence and Perceived Motor Competence: Which Best Predicts Physical Activity among Girls?

    PubMed

    Khodaverdi, Zeinab; Bahram, Abbas; Khalaji, Hassan; Kazemnejad, Anoshirvan

    2013-10-01

    The main purpose of this study was to determine which correlate, perceived motor competence or motor skill competence, best predicts girls' physical activity behavior. A sample of 352 girls (mean age=8.7, SD=0.3 yr) participated in this study. To assess motor skill competence and perceived motor competence, each child completed the Test of Gross Motor Development-2 and Physical Ability sub-scale of Marsh's Self-Description Questionnaire. Children's physical activity was assessed by the Physical Activity Questionnaire for Older Children. Multiple linear regression model was used to determine whether perceived motor competence or motor skill competence best predicts moderate-to-vigorous self-report physical activity. Multiple regression analysis indicated that motor skill competence and perceived motor competence predicted 21% variance in physical activity (R(2)=0.21, F=48.9, P=0.001), and motor skill competence (R(2)=0.15, ᵝ=0.33, P= 0.001) resulted in more variance than perceived motor competence (R(2)=0.06, ᵝ=0.25, P=0.001) in physical activity. Results revealed motor skill competence had more influence in comparison with perceived motor competence on physical activity level. We suggest interventional programs based on motor skill competence and perceived motor competence should be administered or implemented to promote physical activity in young girls.

  5. Parametric Covariance Model for Horizon-Based Optical Navigation

    NASA Technical Reports Server (NTRS)

    Hikes, Jacob; Liounis, Andrew J.; Christian, John A.

    2016-01-01

    This Note presents an entirely parametric version of the covariance for horizon-based optical navigation measurements. The covariance can be written as a function of only the spacecraft position, two sensor design parameters, the illumination direction, the size of the observed planet, the size of the lit arc to be used, and the total number of observed horizon points. As a result, one may now more clearly understand the sensitivity of horizon-based optical navigation performance as a function of these key design parameters, which is insight that was obscured in previous (and nonparametric) versions of the covariance. Finally, the new parametric covariance is shown to agree with both the nonparametric analytic covariance and results from a Monte Carlo analysis.

  6. Semi-Markov models for interval censored transient cognitive states with back transitions and a competing risk

    PubMed Central

    Wei, Shaoceng; Kryscio, Richard J.

    2015-01-01

    Continuous-time multi-state stochastic processes are useful for modeling the flow of subjects from intact cognition to dementia with mild cognitive impairment and global impairment as intervening transient, cognitive states and death as a competing risk (Figure 1). Each subject's cognition is assessed periodically resulting in interval censoring for the cognitive states while death without dementia is not interval censored. Since back transitions among the transient states are possible, Markov chains are often applied to this type of panel data. In this manuscript we apply a Semi-Markov process in which we assume that the waiting times are Weibull distributed except for transitions from the baseline state, which are exponentially distributed and in which we assume no additional changes in cognition occur between two assessments. We implement a quasi-Monte Carlo (QMC) method to calculate the higher order integration needed for likelihood estimation. We apply our model to a real dataset, the Nun Study, a cohort of 461 participants. PMID:24821001

  7. Semi-Markov models for interval censored transient cognitive states with back transitions and a competing risk.

    PubMed

    Wei, Shaoceng; Kryscio, Richard J

    2016-12-01

    Continuous-time multi-state stochastic processes are useful for modeling the flow of subjects from intact cognition to dementia with mild cognitive impairment and global impairment as intervening transient cognitive states and death as a competing risk. Each subject's cognition is assessed periodically resulting in interval censoring for the cognitive states while death without dementia is not interval censored. Since back transitions among the transient states are possible, Markov chains are often applied to this type of panel data. In this manuscript, we apply a semi-Markov process in which we assume that the waiting times are Weibull distributed except for transitions from the baseline state, which are exponentially distributed and in which we assume no additional changes in cognition occur between two assessments. We implement a quasi-Monte Carlo (QMC) method to calculate the higher order integration needed for likelihood estimation. We apply our model to a real dataset, the Nun Study, a cohort of 461 participants. © The Author(s) 2014.

  8. Extended parametric gain range in photonic crystal fibers with strongly frequency-dependent field distributions.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2014-08-15

    The parametric gain range of a degenerate four-wave mixing process is determined in the undepleted pump regime. The gain range is considered with and without taking the mode field distributions of the four-wave mixing components into account. It is found that the mode field distributions have to be included to evaluate the parametric gain correctly in dispersion-tailored speciality fibers and that mode profile engineering can provide a way to increase the parametric gain range.

  9. Four-wave parametric oscillation in sodium vapor by electromagnetically induced diffraction.

    PubMed

    Harada, Ken-ichi; Ogata, Minoru; Mitsunaga, Masaharu

    2007-05-01

    We have observed a novel type of parametric oscillation in sodium atomic vapor where four off-axis signal waves simultaneously build up under resonant and counterpropagating pump beams with elliptical beam profiles. The four waves, two of them Stokes shifted and the other two anti-Stokes shifted, have similar output powers of up to 10 mW with a conversion efficiency of 30% and are parametrically coupled by electromagnetically induced diffraction.

  10. Latent component-based gear tooth fault detection filter using advanced parametric modeling

    NASA Astrophysics Data System (ADS)

    Ettefagh, M. M.; Sadeghi, M. H.; Rezaee, M.; Chitsaz, S.

    2009-10-01

    In this paper, a new parametric model-based filter is proposed for gear tooth fault detection. The designing of the filter consists of identifying the most proper latent component (LC) of the undamaged gearbox signal by analyzing the instant modules (IMs) and instant frequencies (IFs) and then using the component with lowest IM as the proposed filter output for detecting fault of the gearbox. The filter parameters are estimated by using the LC theory in which an advanced parametric modeling method has been implemented. The proposed method is applied on the signals, extracted from simulated gearbox for detection of the simulated gear faults. In addition, the method is used for quality inspection of the produced Nissan-Junior vehicle gearbox by gear profile error detection in an industrial test bed. For evaluation purpose, the proposed method is compared with the previous parametric TAR/AR-based filters in which the parametric model residual is considered as the filter output and also Yule-Walker and Kalman filter are implemented for estimating the parameters. The results confirm the high performance of the new proposed fault detection method.

  11. Direct 4D reconstruction of parametric images incorporating anato-functional joint entropy.

    PubMed

    Tang, Jing; Kuwabara, Hiroto; Wong, Dean F; Rahmim, Arman

    2010-08-07

    We developed an anatomy-guided 4D closed-form algorithm to directly reconstruct parametric images from projection data for (nearly) irreversible tracers. Conventional methods consist of individually reconstructing 2D/3D PET data, followed by graphical analysis on the sequence of reconstructed image frames. The proposed direct reconstruction approach maintains the simplicity and accuracy of the expectation-maximization (EM) algorithm by extending the system matrix to include the relation between the parametric images and the measured data. A closed-form solution was achieved using a different hidden complete-data formulation within the EM framework. Furthermore, the proposed method was extended to maximum a posterior reconstruction via incorporation of MR image information, taking the joint entropy between MR and parametric PET features as the prior. Using realistic simulated noisy [(11)C]-naltrindole PET and MR brain images/data, the quantitative performance of the proposed methods was investigated. Significant improvements in terms of noise versus bias performance were demonstrated when performing direct parametric reconstruction, and additionally upon extending the algorithm to its Bayesian counterpart using the MR-PET joint entropy measure.

  12. 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. (c) 2015 APA, all rights reserved).

  13. Development of suspended core soft glass fibers for far-detuned parametric conversion

    NASA Astrophysics Data System (ADS)

    Rampur, Anupamaa; Ciąćka, Piotr; Cimek, Jarosław; Kasztelanic, Rafał; Buczyński, Ryszard; Klimczak, Mariusz

    2018-04-01

    Light sources utilizing χ (2) parametric conversion combine high brightness with attractive operation wavelengths in the near and mid-infrared. In optical fibers, it is possible to use χ (3) degenerate four-wave mixing in order to obtain signal-to-idler frequency detuning of over 100 THz. We report on a test series of nonlinear soft glass suspended core fibers intended for parametric conversion of 1000-1100 nm signal wavelengths available from an array of mature lasers into the near-to-mid-infrared range of 2700-3500 nm under pumping with an erbium sub-picosecond laser system. The presented discussion includes modelling of the fiber properties, details of their physical development and characterization, and experimental tests of parametric conversion.

  14. Parametric Mass Modeling for Mars Entry, Descent and Landing System Analysis Study

    NASA Technical Reports Server (NTRS)

    Samareh, Jamshid A.; Komar, D. R.

    2011-01-01

    This paper provides an overview of the parametric mass models used for the Entry, Descent, and Landing Systems Analysis study conducted by NASA in FY2009-2010. The study examined eight unique exploration class architectures that included elements such as a rigid mid-L/D aeroshell, a lifting hypersonic inflatable decelerator, a drag supersonic inflatable decelerator, a lifting supersonic inflatable decelerator implemented with a skirt, and subsonic/supersonic retro-propulsion. Parametric models used in this study relate the component mass to vehicle dimensions and mission key environmental parameters such as maximum deceleration and total heat load. The use of a parametric mass model allows the simultaneous optimization of trajectory and mass sizing parameters.

  15. Validation of two (parametric vs non-parametric) daily weather generators

    NASA Astrophysics Data System (ADS)

    Dubrovsky, M.; Skalak, P.

    2015-12-01

    As the climate models (GCMs and RCMs) fail to satisfactorily reproduce the real-world surface weather regime, various statistical methods are applied to downscale GCM/RCM outputs into site-specific weather series. The stochastic weather generators are among the most favourite downscaling methods capable to produce realistic (observed-like) meteorological inputs for agrological, hydrological and other impact models used in assessing sensitivity of various ecosystems to climate change/variability. To name their advantages, the generators may (i) produce arbitrarily long multi-variate synthetic weather series representing both present and changed climates (in the latter case, the generators are commonly modified by GCM/RCM-based climate change scenarios), (ii) be run in various time steps and for multiple weather variables (the generators reproduce the correlations among variables), (iii) be interpolated (and run also for sites where no weather data are available to calibrate the generator). This contribution will compare two stochastic daily weather generators in terms of their ability to reproduce various features of the daily weather series. M&Rfi is a parametric generator: Markov chain model is used to model precipitation occurrence, precipitation amount is modelled by the Gamma distribution, and the 1st order autoregressive model is used to generate non-precipitation surface weather variables. The non-parametric GoMeZ generator is based on the nearest neighbours resampling technique making no assumption on the distribution of the variables being generated. Various settings of both weather generators will be assumed in the present validation tests. The generators will be validated in terms of (a) extreme temperature and precipitation characteristics (annual and 30-years extremes and maxima of duration of hot/cold/dry/wet spells); (b) selected validation statistics developed within the frame of VALUE project. The tests will be based on observational weather series

  16. Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

    NASA Astrophysics Data System (ADS)

    Bowen, Trevor A.; Badman, Samuel; Hellinger, Petr; Bale, Stuart D.

    2018-02-01

    Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfvén wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfvén waves.

  17. Motor Skill Competence and Perceived Motor Competence: Which Best Predicts Physical Activity among Girls?

    PubMed Central

    Khodaverdi, Zeinab; Bahram, Abbas; Khalaji, Hassan; Kazemnejad, Anoshirvan

    2013-01-01

    Abstract Background The main purpose of this study was to determine which correlate, perceived motor competence or motor skill competence, best predicts girls’ physical activity behavior. Methods A sample of 352 girls (mean age=8.7, SD=0.3 yr) participated in this study. To assess motor skill competence and perceived motor competence, each child completed the Test of Gross Motor Development-2 and Physical Ability sub-scale of Marsh’s Self-Description Questionnaire. Children’s physical activity was assessed by the Physical Activity Questionnaire for Older Children. Multiple linear regression model was used to determine whether perceived motor competence or motor skill competence best predicts moderate-to-vigorous self-report physical activity. Results Multiple regression analysis indicated that motor skill competence and perceived motor competence predicted 21% variance in physical activity (R2=0.21, F=48.9, P=0.001), and motor skill competence (R2=0.15, ᵝ=0.33, P= 0.001) resulted in more variance than perceived motor competence (R2=0.06, ᵝ=0.25, P=0.001) in physical activity. Conclusion Results revealed motor skill competence had more influence in comparison with perceived motor competence on physical activity level. We suggest interventional programs based on motor skill competence and perceived motor competence should be administered or implemented to promote physical activity in young girls. PMID:26060623

  18. 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.

  19. Mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects for longitudinal-competing risks data analysis.

    PubMed

    Lu, Tao; Wang, Min; Liu, Guangying; Dong, Guang-Hui; Qian, Feng

    2016-01-01

    It is well known that there is strong relationship between HIV viral load and CD4 cell counts in AIDS studies. However, the relationship between them changes during the course of treatment and may vary among individuals. During treatments, some individuals may experience terminal events such as death. Because the terminal event may be related to the individual's viral load measurements, the terminal mechanism is non-ignorable. Furthermore, there exists competing risks from multiple types of events, such as AIDS-related death and other death. Most joint models for the analysis of longitudinal-survival data developed in literatures have focused on constant coefficients and assume symmetric distribution for the endpoints, which does not meet the needs for investigating the nature of varying relationship between HIV viral load and CD4 cell counts in practice. We develop a mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects to deal with varying relationship between the two endpoints for longitudinal-competing risks survival data. A fully Bayesian inference procedure is established to estimate parameters in the joint model. The proposed method is applied to a multicenter AIDS cohort study. Various scenarios-based potential models that account for partial data features are compared. Some interesting findings are presented.

  20. Model risk for European-style stock index options.

    PubMed

    Gençay, Ramazan; Gibson, Rajna

    2007-01-01

    In empirical modeling, there have been two strands for pricing in the options literature, namely the parametric and nonparametric models. Often, the support for the nonparametric methods is based on a benchmark such as the Black-Scholes (BS) model with constant volatility. In this paper, we study the stochastic volatility (SV) and stochastic volatility random jump (SVJ) models as parametric benchmarks against feedforward neural network (FNN) models, a class of neural network models. Our choice for FNN models is due to their well-studied universal approximation properties of an unknown function and its partial derivatives. Since the partial derivatives of an option pricing formula are risk pricing tools, an accurate estimation of the unknown option pricing function is essential for pricing and hedging. Our findings indicate that FNN models offer themselves as robust option pricing tools, over their sophisticated parametric counterparts in predictive settings. There are two routes to explain the superiority of FNN models over the parametric models in forecast settings. These are nonnormality of return distributions and adaptive learning.

  1. Model Adaptation in Parametric Space for POD-Galerkin Models

    NASA Astrophysics Data System (ADS)

    Gao, Haotian; Wei, Mingjun

    2017-11-01

    The development of low-order POD-Galerkin models is largely motivated by the expectation to use the model developed with a set of parameters at their native values to predict the dynamic behaviors of the same system under different parametric values, in other words, a successful model adaptation in parametric space. However, most of time, even small deviation of parameters from their original value may lead to large deviation or unstable results. It has been shown that adding more information (e.g. a steady state, mean value of a different unsteady state, or an entire different set of POD modes) may improve the prediction of flow with other parametric states. For a simple case of the flow passing a fixed cylinder, an orthogonal mean mode at a different Reynolds number may stabilize the POD-Galerkin model when Reynolds number is changed. For a more complicated case of the flow passing an oscillatory cylinder, a global POD-Galerkin model is first applied to handle the moving boundaries, then more information (e.g. more POD modes) is required to predicate the flow under different oscillatory frequencies. Supported by ARL.

  2. Probing the dynamics of dark energy with divergence-free parametrizations: A global fit study

    NASA Astrophysics Data System (ADS)

    Li, Hong; Zhang, Xin

    2011-09-01

    The CPL parametrization is very important for investigating the property of dark energy with observational data. However, the CPL parametrization only respects the past evolution of dark energy but does not care about the future evolution of dark energy, since w ( z ) diverges in the distant future. In a recent paper [J.Z. Ma, X. Zhang, Phys. Lett. B 699 (2011) 233], a robust, novel parametrization for dark energy, w ( z ) = w + w ( l n ( 2 + z ) 1 + z - l n 2 ) , has been proposed, successfully avoiding the future divergence problem in the CPL parametrization. On the other hand, an oscillating parametrization (motivated by an oscillating quintom model) can also avoid the future divergence problem. In this Letter, we use the two divergence-free parametrizations to probe the dynamics of dark energy in the whole evolutionary history. In light of the data from 7-year WMAP temperature and polarization power spectra, matter power spectrum of SDSS DR7, and SN Ia Union2 sample, we perform a full Markov Chain Monte Carlo exploration for the two dynamical dark energy models. We find that the best-fit dark energy model is a quintom model with the EOS across -1 during the evolution. However, though the quintom model is more favored, we find that the cosmological constant still cannot be excluded.

  3. Future orientation and competence to stand trial: the fragility of competence.

    PubMed

    Kivisto, Aaron J; Moore, Todd M; Fite, Paula A; Seidner, Bruce G

    2011-01-01

    The current study examined the direct, indirect, and interactive effects of age, intellectual ability, psychiatric symptomatology, and future orientation on juvenile adjudicative competence utilizing a secondary sample of 927 youth from the MacArthur Juvenile Adjudicative Competence Study. Consistent with previous research, age, intellectual ability, and future orientation were found to be positively associated with competence, and psychiatric symptomatology was weakly negatively related to competence. Tests of indirect effects revealed that the development of an orientation toward future consequences partially explains the relationship between age and the capacity to reason about legal decision-making. Further, tests of invariance revealed that the competence of immature adolescents is particularly "fragile," in that smaller deficits in cognitive abilities appear to pose greater problems in youths regarding their adjudicative competence than in their more mature peers. Findings are discussed in regard to forensic practice as well as for future research.

  4. Quantifying parametric uncertainty in the Rothermel model

    Treesearch

    S. Goodrick

    2008-01-01

    The purpose of the present work is to quantify parametric uncertainty in the Rothermel wildland fire spreadmodel (implemented in software such as fire spread models in the United States. This model consists of a non-linear system of equations that relates environmentalvariables (input parameter groups...

  5. New Logic Circuit with DC Parametric Excitation

    NASA Astrophysics Data System (ADS)

    Sugahara, Masanori; Kaneda, Hisayoshi

    1982-12-01

    It is shown that dc parametric excitation is possible in a circuit named JUDO, which is composed of two resistively-connected Josephson junctions. Simulation study proves that the circuit has large gain and properties suitable for the construction of small, high-speed logic circuits.

  6. Nearly noiseless amplification of microwave signals with a Josephson parametric amplifier

    NASA Astrophysics Data System (ADS)

    Castellanos-Beltran, Manuel

    2009-03-01

    A degenerate parametric amplifier transforms an incident coherent state by amplifying one of its quadrature components while deamplifying the other. This transformation, when performed by an ideal parametric amplifier, is completely deterministic and reversible; therefore the amplifier in principle can be noiseless. We attempt to realize a noiseless amplifier of this type at microwave frequencies with a Josephson parametric amplifier (JPA). To this end, we have built a superconducting microwave cavity containing many dc-SQUIDs. This arrangement creates a non-linear medium in a cavity and it is closely analogous to an optical parametric amplifier. In my talk, I will describe the current performance of this circuit, where I show I can amplify signals with less added noise than a quantum-limited amplifier that amplifies both quadratures. In addition, the JPA also squeezes the electromagnetic vacuum fluctuations by 10 dB. Finally, I will discuss our effort to put two such amplifiers in series in order to undo the first stage of squeezing with a second stage of amplification, demonstrating that the amplification process is truly reversible.[4pt] M. A. Castellanos-Beltran, K. D. Irwin, G. C. Hilton, L. R. Vale and K. W. Lehnert, Nature Physics, published on line, http://dx.doi.org/10.1038/nphys1090 (2008).

  7. Josephson Parametric Amplifer Based on a Cavity-Embedded Cooper Pair Transistor

    NASA Astrophysics Data System (ADS)

    Li, Juliang; Rimberg, A. J.

    In this experiment a cavity-embedded Cooper-pair transistor (cCPT) is used as a Josephson parametric amplifier. The cCPT consists of a Cooper pair transistor placed at the voltage antinode of a 5.7 GHz shorted quarter-wave resonator so that the CPT provides a galvanic connection between the cavity's central conductor and ground plane, which forms a SQUID loop. Both the flux threading the loop as well as the gate charge can be modulated, and each can provide the parametric pumping. The reflected signal from the cCPT is further amplified by both SLUG and HEMT amplifiers for characterizing the parametric amplification. A first application of the parametric amplification is to improve the charge sensitivity of a single electron charge detector. This can be done either by pumping on a side band or by shifting the charge state of the cCPT near a bifurcation point. Stimulated emission has been also observed when the cCPT is pumped at twice the resonant frequency in the absence of an input signal. This could allow investigation of the dynamic Casimir effect as well as generation of non-classical photon states. Supported by Grants ARO W911NF-13-10377 and NSF DMR 1507400.

  8. Heating and thermal squeezing in parametrically driven oscillators with added noise.

    PubMed

    Batista, Adriano A

    2012-11-01

    In this paper we report a theoretical model based on Green's functions, Floquet theory, and averaging techniques up to second order that describes the dynamics of parametrically driven oscillators with added thermal noise. Quantitative estimates for heating and quadrature thermal noise squeezing near and below the transition line of the first parametric instability zone of the oscillator are given. Furthermore, we give an intuitive explanation as to why heating and thermal squeezing occur. For small amplitudes of the parametric pump the Floquet multipliers are complex conjugate of each other with a constant magnitude. As the pump amplitude is increased past a threshold value in the stable zone near the first parametric instability, the two Floquet multipliers become real and have different magnitudes. This creates two different effective dissipation rates (one smaller and the other larger than the real dissipation rate) along the stable manifolds of the first-return Poincaré map. We also show that the statistical average of the input power due to thermal noise is constant and independent of the pump amplitude and frequency. The combination of these effects causes most of heating and thermal squeezing. Very good agreement between analytical and numerical estimates of the thermal fluctuations is achieved.

  9. Fuel cell on-site integrated energy system parametric analysis of a residential complex

    NASA Technical Reports Server (NTRS)

    Simons, S. N.

    1977-01-01

    A parametric energy-use analysis was performed for a large apartment complex served by a fuel cell on-site integrated energy system (OS/IES). The variables parameterized include operating characteristics for four phosphoric acid fuel cells, eight OS/IES energy recovery systems, and four climatic locations. The annual fuel consumption for selected parametric combinations are presented and a breakeven economic analysis is presented for one parametric combination. The results show fuel cell electrical efficiency and system component choice have the greatest effect on annual fuel consumption; fuel cell thermal efficiency and geographic location have less of an effect.

  10. Comprehensive schoolteachers at risk of early exit from work.

    PubMed

    Mykletun, R J; Mykletun, A

    1999-01-01

    Risk of early exit from work for teachers was operationalized as high burnout scores, working part-time due to heavy burden and illness or working part-time while also receiving partial disability pension. Data were collected by mailed questionnaires in a cross-sectional study to a random sample of Norwegian comprehensive schoolteachers, response rate = 86% (N = 1860 valid cases). High age increased the risk of early exit from work, but for cynicism the age effect disappeared when sense of competence and stress were introduced in the regression model. Age had no effect for low professional efficacy. Sense of competence effected burnout, but actual competence level and the gap between actual competence and teaching obligations did not. Stress effected all measures of risk of early exit, especially exhaustion. Change as stress factor increased the exhaustion scores, and were also relevant to risk of having a part-time position, and/or partial disability pension.

  11. Risk-adjusted capitation payments for catastrophic risks based on multi-year prior costs.

    PubMed

    van Barneveld, E M; van Vliet, R C; van de Ven, W P

    1997-02-01

    In many countries regulated competition among health insurance companies has recently been proposed or implemented. A crucial issue is whether or not the benefits package offered by competing insurers should also cover catastrophic risks (like several forms of expensive long-term care) in addition to non-catastrophic risks (like hospital care and physician services). In 1988 the Dutch government proposed compulsory national health insurance based on regulated competition among insurer as well as among providers of care. The competing insurers should offer a benefits package covering both non-catastrophic risks and catastrophic risks. The insurers would be largely financed via risk-adjusted capitation payments. The government intended to use a capitation formula that is, besides some demographic variables, based on multi-year prior costs. This paper presents the results of an explorative empirical analysis of the possible consequences of such a capitation formula for catastrophic risks. The main conclusion is that this formula would be inadequate because it would leave ample room for cream skimming.

  12. Z/sub n/ Baxter model: symmetries and the Belavin parametrization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richey, M.P.; Tracy, C.A.

    1986-02-01

    The Z/sub n/ Baxter model is an exactly solvable lattice model in the special case of the Belavin parametrization. For this parametrization the authors calculate the partition function in an antiferromagnetic region and the order parameter in a ferromagnetic region. They find that the order parameter is expressible in terms of a modular function of level n which for n=2 is the Onsager-Yang-Baxter result. In addition they determine the symmetry group of the finite lattice partition function for the general Z/sub n/ Baxter model.

  13. Generalized parametric down conversion, many particle interferometry, and Bell's theorem

    NASA Technical Reports Server (NTRS)

    Choi, Hyung Sup

    1992-01-01

    A new field of multi-particle interferometry is introduced using a nonlinear optical spontaneous parametric down conversion (SPDC) of a photon into more than two photons. The study of SPDC using a realistic Hamiltonian in a multi-mode shows that at least a low conversion rate limit is possible. The down converted field exhibits many stronger nonclassical phenomena than the usual two photon parametric down conversion. Application of the multi-particle interferometry to a recently proposed many particle Bell's theorem on the Einstein-Podolsky-Rosen problem is given.

  14. Competences for All: Recognizing and Developing Competences of Young People with Fewer Opportunities

    ERIC Educational Resources Information Center

    Usakli, Hakan

    2016-01-01

    This qualitative study clarifies opinion of 32 European volunteer youth leaders on concepts of competence, fewer opportunities and enlargement strategies on competence of fewer opportunities. Leaders underline main competencies as follows: tongue, languages, mathematical, digital, learning, social, entrepreneurship, cultural. Key competences are…

  15. Wavelength-doubling optical parametric oscillator

    DOEpatents

    Armstrong, Darrell J [Albuquerque, NM; Smith, Arlee V [Albuquerque, NM

    2007-07-24

    A wavelength-doubling optical parametric oscillator (OPO) comprising a type II nonlinear optical medium for generating a pair of degenerate waves at twice a pump wavelength and a plurality of mirrors for rotating the polarization of one wave by 90 degrees to produce a wavelength-doubled beam with an increased output energy by coupling both of the degenerate waves out of the OPO cavity through the same output coupler following polarization rotation of one of the degenerate waves.

  16. Parametric Oscillation, Frequency Mixing, and Injection Locking of Strongly Coupled Nanomechanical Resonator Modes.

    PubMed

    Seitner, Maximilian J; Abdi, Mehdi; Ridolfo, Alessandro; Hartmann, Michael J; Weig, Eva M

    2017-06-23

    We study locking phenomena of two strongly coupled, high quality factor nanomechanical resonator modes to a common parametric drive at a single drive frequency in different parametric driving regimes. By controlled dielectric gradient forces we tune the resonance frequencies of the flexural in-plane and out-of-plane oscillation of the high stress silicon nitride string through their mutual avoided crossing. For the case of the strong common parametric drive signal-idler generation via nondegenerate parametric two-mode oscillation is observed. Broadband frequency tuning of the very narrow linewidth signal and idler resonances is demonstrated. When the resonance frequencies of the signal and idler get closer to each other, partial injection locking, injection pulling, and complete injection locking to half of the drive frequency occurs depending on the pump strength. Furthermore, satellite resonances, symmetrically offset from the signal and idler by their beat note, are observed, which can be attributed to degenerate four-wave mixing in the highly nonlinear mechanical oscillations.

  17. Competencies for the 21st Century Information Professional: Translating the SLA Competencies into Business Competencies.

    ERIC Educational Resources Information Center

    Henczel, Sue

    This paper examines how the Special Libraries Association competencies can be mapped to the broader business competencies of marketing (promoting), packaging (product development), persuading and performing (sales/customer service), and positioning (strategic maneuvering). It introduces a process whereby the skills, knowledge, understandings, and…

  18. Stimulated parametric emission microscopy.

    PubMed

    Isobe, Keisuke; Kataoka, Shogo; Murase, Rena; Watanabe, Wataru; Higashi, Tsunehito; Kawakami, Shigeki; Matsunaga, Sachihiro; Fukui, Kiichi; Itoh, Kazuyoshi

    2006-01-23

    We propose a novel microscopy technique based on the four-wave mixing (FWM) process that is enhanced by two-photon electronic resonance induced by a pump pulse along with stimulated emission induced by a dump pulse. A Ti:sapphire laser and an optical parametric oscillator are used as light sources for the pump and dump pulses, respectively. We demonstrate that our proposed FWM technique can be used to obtain a one-dimensional image of ethanol-thinned Coumarin 120 solution sandwiched between a hole-slide glass and a cover slip, and a two-dimensional image of a leaf of Camellia sinensis.

  19. On risk and decisional capacity.

    PubMed

    Checkland, D

    2001-02-01

    Limits to paternalism are, in the liberal democracies, partially defined by the concepts of decision-making capacity/incapacity (mental competence/incompetence). The paper is a response to Ian Wilks's (1997) recent attempt to defend the idea that the standards for decisional capacity ought to vary with the degree of risk incurred by certain choices. Wilks's defense is based on a direct appeal to the logical features of examples and analogies, thus attempting to by-pass earlier criticisms (e.g., Culver & Gert, 1990) of risk-based standards. Wilks's argument is found wanting on the grounds that he misconstrues the logic of such capacity, especially in accounting for conceptual and pragmatic ties with issues of decisional authority. A diagnosis is offered as to the source of Wilks's error (the assumption that mental competence is a species of wider genus of "competence"), and an alternative way of accounting for risk within the predominant contemporary legal framework is sketched.

  20. Competence, practical rationality and what a patient values.

    PubMed

    Craigie, Jillian

    2011-07-01

    According to the principle of patient autonomy, patients have the right to be self-determining in decisions about their own medical care, which includes the right to refuse treatment. However, a treatment refusal may legitimately be overridden in cases where the decision is judged to be incompetent. It has recently been proposed that in assessments of competence, attention should be paid to the evaluative judgments that guide patients' treatment decisions. In this paper I examine this claim in light of theories of practical rationality, focusing on the difficult case of an anorexic person who is judged to be competent and refuses treatment, thereby putting themselves at risk of serious harm. I argue that the standard criteria for competence assess whether a treatment decision satisfies the goals of practical decision-making, and that this same criterion can be applied to a patient's decision-guiding commitments. As a consequence I propose that a particular understanding of practical rationality offers a theoretical framework for justifying involuntary treatment in the anorexia case. © 2009 Blackwell Publishing Ltd.

  1. Universal Stabilization of a Parametrically Coupled Qubit

    NASA Astrophysics Data System (ADS)

    Lu, Yao; Chakram, S.; Leung, N.; Earnest, N.; Naik, R. K.; Huang, Ziwen; Groszkowski, Peter; Kapit, Eliot; Koch, Jens; Schuster, David I.

    2017-10-01

    We autonomously stabilize arbitrary states of a qubit through parametric modulation of the coupling between a fixed frequency qubit and resonator. The coupling modulation is achieved with a tunable coupling design, in which the qubit and the resonator are connected in parallel to a superconducting quantum interference device. This allows for quasistatic tuning of the qubit-cavity coupling strength from 12 MHz to more than 300 MHz. Additionally, the coupling can be dynamically modulated, allowing for single-photon exchange in 6 ns. Qubit coherence times exceeding 20 μ s are maintained over the majority of the range of tuning, limited primarily by the Purcell effect. The parametric stabilization technique realized using the tunable coupler involves engineering the qubit bath through a combination of photon nonconserving sideband interactions realized by flux modulation, and direct qubit Rabi driving. We demonstrate that the qubit can be stabilized to arbitrary states on the Bloch sphere with a worst-case fidelity exceeding 80%.

  2. Wavelength-agile near-IR optical parametric oscillator using a deposited silicon waveguide.

    PubMed

    Wang, Ke-Yao; Foster, Mark A; Foster, Amy C

    2015-06-15

    Using a deposited hydrogenated amorphous silicon (a-Si:H) waveguide, we demonstrate ultra-broad bandwidth (60 THz) parametric amplification via four-wave mixing (FWM), and subsequently achieve the first silicon optical parametric oscillator (OPO) at near-IR wavelengths. Utilization of the time-dispersion-tuned technique provides an optical source with active wavelength tuning over 42 THz with a fixed pump wave.

  3. Beyond NAVMEC: competency-based veterinary education and assessment of the professional competencies.

    PubMed

    Hodgson, Jennifer L; Pelzer, Jacquelyn M; Inzana, Karen D

    2013-01-01

    The implementation of competency-based curricula within the health sciences has been an important paradigm shift over the past 30 years. As a result, one of the five strategic goals recommended by the North American Veterinary Medical Education Consortium (NAVMEC) report was to graduate career-ready veterinarians who are proficient in, and have the confidence to use, an agreed-upon set of core competencies. Of the nine competencies identified as essential for veterinary graduates, seven could be classified as professional or non-technical competencies: communication; collaboration; management (self, team, system); lifelong learning, scholarship, value of research; leadership; diversity and multicultural awareness; and adaptation to changing environments. Traditionally, the professional competencies have received less attention in veterinary curricula and their assessment is often sporadic or inconsistent. In contrast, the same or similar competencies are being increasingly recognized in other health professions as essential skills and abilities, and their assessment is being undertaken with enhanced scrutiny and critical appraisal. Several challenges have been associated with the assessment of professional competencies, including agreement as to their definition and therefore their evaluation, the fact that they are frequently complex and require multiple integrative assessments, and the ability and/or desire of faculty to teach and assess these competencies. To provide an improved context for assessment of the seven professional competencies identified in the NAVMEC report, this article describes a broad framework for their evaluation as well as specific examples of how these or similar competencies are currently being measured in medical and veterinary curricula.

  4. Competency Maps: an Effective Model to Integrate Professional Competencies Across a STEM Curriculum

    NASA Astrophysics Data System (ADS)

    Sánchez Carracedo, Fermín; Soler, Antonia; Martín, Carme; López, David; Ageno, Alicia; Cabré, Jose; Garcia, Jordi; Aranda, Joan; Gibert, Karina

    2018-05-01

    Curricula designed in the context of the European Higher Education Area need to be based on both domain-specific and professional competencies. Whereas universities have had extensive experience in developing students' domain-specific competencies, fostering professional competencies poses a new challenge we need to face. This paper presents a model to globally develop professional competencies in a STEM (science, technology, engineering, and mathematics) degree program, and assesses the results of its implementation after 4 years. The model is based on the use of competency maps, in which each competency is defined in terms of competency units. Each competency unit is described by a set of expected learning outcomes at three domain levels. This model allows careful analysis, revision, and iteration for an effective integration of professional competencies in domain-specific subjects. A global competency map is also designed, including all the professional competency learning outcomes to be achieved throughout the degree. This map becomes a useful tool for curriculum designers and coordinators. The results were obtained from four sources: (1) students' grades (classes graduated from 2013 to 2016, the first 4 years of the new Bachelor's Degree in Informatics Engineering at the Barcelona School of Informatics); (2) students' surveys (answered by students when they finished the degree); (3) the government employment survey, where former students evaluate their satisfaction of the received training in the light of their work experience; and (4) the Everis Foundation University-Enterprise Ranking, answered by over 2000 employers evaluating their satisfaction regarding their employees' university training, where the Barcelona School of Informatics scores first in the national ranking. The results show that competency maps are a good tool for developing professional competencies in a STEM degree.

  5. Parametric Analysis of Light Truck and Automobile Maintenance

    DOT National Transportation Integrated Search

    1979-05-01

    Utilizing the Automotive and Light Truck Service and Repair Data Base developed in the campanion report, parametric analyses were made of the relationships between maintenance costs, schduled and unschduled, and vehicle parameters; body class, manufa...

  6. Core Competencies and the Prevention of Adolescent Substance Use

    ERIC Educational Resources Information Center

    Haegerich, Tamara M.; Tolan, Patrick H.

    2008-01-01

    Adolescence is a developmental period during which youth are at increased risk for using substances. An empirical focus on core competencies illustrates that youth are less likely to use substances when they have a positive future orientation, a belief in the ability to resist substances, emotional and behavioral control, sound decision-making…

  7. Competencies for disaster mental health.

    PubMed

    King, Richard V; Burkle, Frederick M; Walsh, Lauren E; North, Carol S

    2015-03-01

    Competencies for disaster mental health are essential to domestic and international disaster response capabilities. Numerous consensus-based competency sets for disaster health workers exist, but no prior study identifies and discusses competency sets pertaining specifically to disaster mental health. Relevant competency sets were identified via MEDLINE, PsycINFO, EBSCO, and Google Scholar searches. Sixteen competency sets are discussed, some providing core competencies for all disaster responders and others for specific responder groups within particular professions or specialties. Competency sets specifically for disaster mental health professionals are lacking, with the exception of one set that focused only on cultural competence. The identified competency sets provide guidance for educators in developing disaster mental health curricula and for disaster health workers seeking education and training in disaster mental health. Valid, criterion-based competencies are required to guide selection and training of mental health professionals for the disaster mental health workforce. In developing these competencies, consideration should be given to the requirements of both domestic and international disaster response efforts.

  8. Parametric Study of Sealant Nozzle

    NASA Astrophysics Data System (ADS)

    Yamamoto, Yoshimi

    It has become apparent in recent years the advancement of manufacturing processes in the aerospace industry. Sealant nozzles are a critical device in the use of fuel tank applications for optimal bonds and for ground service support and repair. Sealants has always been a challenging area for optimizing and understanding the flow patterns. A parametric study was conducted to better understand geometric effects of sealant flow and to determine whether the sealant rheology can be numerically modeled. The Star-CCM+ software was used to successfully develop the parametric model, material model, physics continua, and simulate the fluid flow for the sealant nozzle. The simulation results of Semco sealant nozzles showed the geometric effects of fluid flow patterns and the influences from conical area reduction, tip length, inlet diameter, and tip angle parameters. A smaller outlet diameter induced maximum outlet velocity at the exit, and contributed to a high pressure drop. The conical area reduction, tip angle and inlet diameter contributed most to viscosity variation phenomenon. Developing and simulating 2 different flow models (Segregated Flow and Viscous Flow) proved that both can be used to obtain comparable velocity and pressure drop results, however; differences are seen visually in the non-uniformity of the velocity and viscosity fields for the Viscous Flow Model (VFM). A comprehensive simulation setup for sealant nozzles was developed so other analysts can utilize the data.

  9. Parametric instability, inverse cascade and the range of solar-wind turbulence

    NASA Astrophysics Data System (ADS)

    Chandran, Benjamin D. G.

    2018-02-01

    In this paper, weak-turbulence theory is used to investigate the nonlinear evolution of the parametric instability in three-dimensional low- plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are strongly damped. It is shown analytically that the parametric instability leads to an inverse cascade of Alfvén wave quanta, and several exact solutions to the wave kinetic equations are presented. The main results of the paper concern the parametric decay of Alfvén waves that initially satisfy +\\gg e-$ , where +$ and -$ are the frequency ( ) spectra of Alfvén waves propagating in opposite directions along the magnetic field lines. If +$ initially has a peak frequency 0$ (at which +$ is maximized) and an `infrared' scaling p$ at smaller with , then +$ acquires an -1$ scaling throughout a range of frequencies that spreads out in both directions from 0$ . At the same time, -$ acquires an -2$ scaling within this same frequency range. If the plasma parameters and infrared +$ spectrum are chosen to match conditions in the fast solar wind at a heliocentric distance of 0.3 astronomical units (AU), then the nonlinear evolution of the parametric instability leads to an +$ spectrum that matches fast-wind measurements from the Helios spacecraft at 0.3 AU, including the observed -1$ scaling at -4~\\text{Hz}$ . The results of this paper suggest that the -1$ spectrum seen by Helios in the fast solar wind at -4~\\text{Hz}$ is produced in situ by parametric decay and that the -1$ range of +$ extends over an increasingly narrow range of frequencies as decreases below 0.3 AU. This prediction will be tested by measurements from the Parker Solar Probe.

  10. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Isaienko, Oleksandr; Robel, István

    2016-03-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7-20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.

  11. Examining Perception of Competency through Practicum Competencies Outline

    ERIC Educational Resources Information Center

    Esposito, Giovanna; Freda, Maria Francesca; Bosco, Valentina

    2015-01-01

    Purpose: This study aims to examine the self-perceived competencies of 231 Italian students enrolled in a psychological degree program and involved in a practicum. It analyzes the subjective perception of the competences that students expect to develop, acknowledge as developed and that might be inferred from tasks performed during the practicum;…

  12. On performance of parametric and distribution-free models for zero-inflated and over-dispersed count responses.

    PubMed

    Tang, Wan; Lu, Naiji; Chen, Tian; Wang, Wenjuan; Gunzler, Douglas David; Han, Yu; Tu, Xin M

    2015-10-30

    Zero-inflated Poisson (ZIP) and negative binomial (ZINB) models are widely used to model zero-inflated count responses. These models extend the Poisson and negative binomial (NB) to address excessive zeros in the count response. By adding a degenerate distribution centered at 0 and interpreting it as describing a non-risk group in the population, the ZIP (ZINB) models a two-component population mixture. As in applications of Poisson and NB, the key difference between ZIP and ZINB is the allowance for overdispersion by the ZINB in its NB component in modeling the count response for the at-risk group. Overdispersion arising in practice too often does not follow the NB, and applications of ZINB to such data yield invalid inference. If sources of overdispersion are known, other parametric models may be used to directly model the overdispersion. Such models too are subject to assumed distributions. Further, this approach may not be applicable if information about the sources of overdispersion is unavailable. In this paper, we propose a distribution-free alternative and compare its performance with these popular parametric models as well as a moment-based approach proposed by Yu et al. [Statistics in Medicine 2013; 32: 2390-2405]. Like the generalized estimating equations, the proposed approach requires no elaborate distribution assumptions. Compared with the approach of Yu et al., it is more robust to overdispersed zero-inflated responses. We illustrate our approach with both simulated and real study data. Copyright © 2015 John Wiley & Sons, Ltd.

  13. Quantum tomography enhanced through parametric amplification

    NASA Astrophysics Data System (ADS)

    Knyazev, E.; Spasibko, K. Yu; Chekhova, M. V.; Khalili, F. Ya

    2018-01-01

    Quantum tomography is the standard method of reconstructing the Wigner function of quantum states of light by means of balanced homodyne detection. The reconstruction quality strongly depends on the photodetectors quantum efficiency and other losses in the measurement setup. In this article we analyze in detail a protocol of enhanced quantum tomography, proposed by Leonhardt and Paul [1] which allows one to reduce the degrading effect of detection losses. It is based on phase-sensitive parametric amplification, with the phase of the amplified quadrature being scanned synchronously with the local oscillator phase. Although with sufficiently strong amplification the protocol enables overcoming any detection inefficiency, it was so far not implemented in the experiment, probably due to the losses in the amplifier. Here we discuss a possible proof-of-principle experiment with a traveling-wave parametric amplifier. We show that with the state-of-the-art optical elements, the protocol enables high fidelity tomographic reconstruction of bright non-classical states of light. We consider two examples: bright squeezed vacuum and squeezed single-photon state, with the latter being a non-Gaussian state and both strongly affected by the losses.

  14. Terahertz parametric sources and imaging applications

    NASA Astrophysics Data System (ADS)

    Yamashita, M.; Ogawa, Y.; Otani, C.; Kawase, K.

    2005-12-01

    We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of LiNbO 3 or MgO-doped LiNbO 3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We report the detailed characteristics of the oscillation and the radiation including tunability, spatial and temporal coherency, uni directivity, and efficiency. A Fourier transform limited THz-wave spectrum narrowing was achieved by introducing the injection seeding method. Further, we have developed a spectroscopic THz imaging system using a TPO, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis. Several images of the envelope are recorded at different THz frequencies and then processed. The final result is an image that reveals what substances are present in the envelope, in what quantity, and how they are distributed across the envelope area. The example presented here shows the identification of three drugs, two of which illegal, while one is an over-the-counter drug.

  15. Deep Uncertainties in Sea-Level Rise and Storm Surge Projections: Implications for Coastal Flood Risk Management.

    PubMed

    Oddo, Perry C; Lee, Ben S; Garner, Gregory G; Srikrishnan, Vivek; Reed, Patrick M; Forest, Chris E; Keller, Klaus

    2017-09-05

    Sea levels are rising in many areas around the world, posing risks to coastal communities and infrastructures. Strategies for managing these flood risks present decision challenges that require a combination of geophysical, economic, and infrastructure models. Previous studies have broken important new ground on the considerable tensions between the costs of upgrading infrastructure and the damages that could result from extreme flood events. However, many risk-based adaptation strategies remain silent on certain potentially important uncertainties, as well as the tradeoffs between competing objectives. Here, we implement and improve on a classic decision-analytical model (Van Dantzig 1956) to: (i) capture tradeoffs across conflicting stakeholder objectives, (ii) demonstrate the consequences of structural uncertainties in the sea-level rise and storm surge models, and (iii) identify the parametric uncertainties that most strongly influence each objective using global sensitivity analysis. We find that the flood adaptation model produces potentially myopic solutions when formulated using traditional mean-centric decision theory. Moving from a single-objective problem formulation to one with multiobjective tradeoffs dramatically expands the decision space, and highlights the need for compromise solutions to address stakeholder preferences. We find deep structural uncertainties that have large effects on the model outcome, with the storm surge parameters accounting for the greatest impacts. Global sensitivity analysis effectively identifies important parameter interactions that local methods overlook, and that could have critical implications for flood adaptation strategies. © 2017 Society for Risk Analysis.

  16. Contextualizing Competence: Language and LGBT-Based Competency in Health Care.

    PubMed

    Rossi, Alexis L; Lopez, Eliot J

    2017-01-01

    Changes in the language and terminology used to refer to individuals identifying as lesbian, gay, bisexual, and transgender (LGBT), as well as how best to discuss issues of sexual and gender identity, can prove challenging for health care providers due to (1) lack of training; (2) interdisciplinary issues; and (3) prejudices on personal and institutional levels. Given the importance of language in the relationship between health care provider and patient as well as the myriad ways in which language can reflect knowledge, skills, and attitudes, we contend that language is both a facilitator and inhibitor of competence. In this article, we discuss language as a means of exhibiting cultural competence as well as the barriers to facilitating this degree of competence. Communicative competence, a concept traditionally used in linguistics, is discussed as a framework for contextualizing LGBT-specific cultural competence in health care. Ideally, a professional will be considered competent once they (1) acquire a foundation in issues associated with LGBT individuals, as well as a basic understanding of appropriate vocabulary' (2) reconcile personal beliefs with their professional role; (3) create an inclusive healthcare environment such that the influence of personal biases does not negatively impact care; and (4) use identifiers suggested by the patient.

  17. Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion

    NASA Astrophysics Data System (ADS)

    Cho, Minhaeng

    2018-05-01

    Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

  18. Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion.

    PubMed

    Cho, Minhaeng

    2018-05-14

    Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

  19. A Hybrid Wind-Farm Parametrization for Mesoscale and Climate Models

    NASA Astrophysics Data System (ADS)

    Pan, Yang; Archer, Cristina L.

    2018-04-01

    To better understand the potential impact of wind farms on weather and climate at the regional to global scales, a new hybrid wind-farm parametrization is proposed for mesoscale and climate models. The proposed parametrization is a hybrid model because it is not based on physical processes or conservation laws, but on the multiple linear regression of the results of large-eddy simulations (LES) with the geometric properties of the wind-farm layout (e.g., the blockage ratio and blockage distance). The innovative aspect is that each wind turbine is treated individually based on its position in the farm and on the wind direction by predicting the velocity upstream of each turbine. The turbine-induced forces and added turbulence kinetic energy (TKE) are first derived analytically and then implemented in the Weather Research and Forecasting model. Idealized simulations of the offshore Lillgrund wind farm are conducted. The wind-speed deficit and TKE predicted with the hybrid model are in excellent agreement with those from the LES results, while the wind-power production estimated with the hybrid model is within 10% of that observed. Three additional wind farms with larger inter-turbine spacing than at Lillgrund are also considered, and a similar agreement with LES results is found, proving that the hybrid parametrization works well with any wind farm regardless of the spacing between turbines. These results indicate the wind-turbine position, wind direction, and added TKE are essential in accounting for the wind-farm effects on the surroundings, for which the hybrid wind-farm parametrization is a promising tool.

  20. 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?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lucas, John T., E-mail: jolucas@wakehealth.edu; Colmer, Hentry G.; White, Lance

    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 resultantmore » 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.« less