Statistical power for the comparative regression discontinuity design with a nonequivalent comparison group.

PubMed

Tang, Yang; Cook, Thomas D; Kisbu-Sakarya, Yasemin

2018-03-01

In the "sharp" regression discontinuity design (RD), all units scoring on one side of a designated score on an assignment variable receive treatment, whereas those scoring on the other side become controls. Thus the continuous assignment variable and binary treatment indicator are measured on the same scale. Because each must be in the impact model, the resulting multi-collinearity reduces the efficiency of the RD design. However, untreated comparison data can be added along the assignment variable, and a comparative regression discontinuity design (CRD) is then created. When the untreated data come from a non-equivalent comparison group, we call this CRD-CG. Assuming linear functional forms, we show that power in CRD-CG is (a) greater than in basic RD; (b) less sensitive to the location of the cutoff and the distribution of the assignment variable; and that (c) fewer treated units are needed in the basic RD component within the CRD-CG so that savings can result from having fewer treated cases. The theory we develop is used to make numerical predictions about the efficiency of basic RD and CRD-CG relative to each other and to a randomized control trial. Data from the National Head Start Impact study are used to test these predictions. The obtained estimates are closer to the predicted parameters for CRD-CG than for basic RD and are generally quite close to the parameter predictions, supporting the emerging argument that CRD should be the design of choice in many applications for which basic RD is now used. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Regression Discontinuity in Prospective Evaluations: The Case of the FFVP Evaluation

ERIC Educational Resources Information Center

Klerman, Jacob Alex; Olsho, Lauren E. W.; Bartlett, Susan

2015-01-01

While regression discontinuity has usually been applied retrospectively to secondary data, it is even more attractive when applied prospectively. In a prospective design, data collection can be focused on cases near the discontinuity, thereby improving internal validity and substantially increasing precision. Furthermore, such prospective…

Regression discontinuity was a valid design for dichotomous outcomes in three randomized trials.

PubMed

van Leeuwen, Nikki; Lingsma, Hester F; Mooijaart, Simon P; Nieboer, Daan; Trompet, Stella; Steyerberg, Ewout W

2018-06-01

Regression discontinuity (RD) is a quasi-experimental design that may provide valid estimates of treatment effects in case of continuous outcomes. We aimed to evaluate validity and precision in the RD design for dichotomous outcomes. We performed validation studies in three large randomized controlled trials (RCTs) (Corticosteroid Randomization After Significant Head injury [CRASH], the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries [GUSTO], and PROspective Study of Pravastatin in elderly individuals at risk of vascular disease [PROSPER]). To mimic the RD design, we selected patients above and below a cutoff (e.g., age 75 years) randomized to treatment and control, respectively. Adjusted logistic regression models using restricted cubic splines (RCS) and polynomials and local logistic regression models estimated the odds ratio (OR) for treatment, with 95% confidence intervals (CIs) to indicate precision. In CRASH, treatment increased mortality with OR 1.22 [95% CI 1.06-1.40] in the RCT. The RD estimates were 1.42 (0.94-2.16) and 1.13 (0.90-1.40) with RCS adjustment and local regression, respectively. In GUSTO, treatment reduced mortality (OR 0.83 [0.72-0.95]), with more extreme estimates in the RD analysis (OR 0.57 [0.35; 0.92] and 0.67 [0.51; 0.86]). In PROSPER, similar RCT and RD estimates were found, again with less precision in RD designs. We conclude that the RD design provides similar but substantially less precise treatment effect estimates compared with an RCT, with local regression being the preferred method of analysis. Copyright © 2018 Elsevier Inc. All rights reserved.

Grades, Gender, and Encouragement: A Regression Discontinuity Analysis

ERIC Educational Resources Information Center

Owen, Ann L.

2010-01-01

The author employs a regression discontinuity design to provide direct evidence on the effects of grades earned in economics principles classes on the decision to major in economics and finds a differential effect for male and female students. Specifically, for female students, receiving an A for a final grade in the first economics class is…

Evaluating disease management programme effectiveness: an introduction to the regression discontinuity design.

PubMed

Linden, Ariel; Adams, John L; Roberts, Nancy

2006-04-01

Although disease management (DM) has been in existence for over a decade, there is still much uncertainty as to its effectiveness in improving health status and reducing medical cost. The main reason is that most programme evaluations typically follow weak observational study designs that are subject to bias, most notably selection bias and regression to the mean. The regression discontinuity (RD) design may be the best alternative to randomized studies for evaluating DM programme effectiveness. The most crucial element of the RD design is its use of a 'cut-off' score on a pre-test measure to determine assignment to intervention or control. A valuable feature of this technique is that the pre-test measure does not have to be the same as the outcome measure, thus maximizing the programme's ability to use research-based practice guidelines, survey instruments and other tools to identify those individuals in greatest need of the programme intervention. Similarly, the cut-off score can be based on clinical understanding of the disease process, empirically derived, or resource-based. In the RD design, programme effectiveness is determined by a change in the pre-post relationship at the cut-off point. While the RD design is uniquely suitable for DM programme evaluation, its success will depend, in large part, on fundamental changes being made in the way DM programmes identify and assign individuals to the programme intervention.

Estimating Causal Effects of Education Interventions Using a Two-Rating Regression Discontinuity Design: Lessons from a Simulation Study

ERIC Educational Resources Information Center

Porter, Kristin E.; Reardon, Sean F.; Unlu, Fatih; Bloom, Howard S.; Robinson-Cimpian, Joseph P.

2014-01-01

A valuable extension of the single-rating regression discontinuity design (RDD) is a multiple-rating RDD (MRRDD). To date, four main methods have been used to estimate average treatment effects at the multiple treatment frontiers of an MRRDD: the "surface" method, the "frontier" method, the "binding-score" method, and…

The Impact of School Improvement Grants on Achievement: Plans for a National Evaluation Using a Regression Discontinuity Design

ERIC Educational Resources Information Center

Deke, John; Dragoset, Lisa

2015-01-01

Does receipt of School Improvement Grants (SIG) funding to implement a school intervention model have an impact on outcomes for low-performing schools? This study answers this question using a regression discontinuity design (RDD) that exploits cutoff values on the continuous variables used to define SIG eligibility tiers, comparing outcomes in…

Using a Regression Discontinuity Design to Determine the Effectiveness of a Vocabulary Intervention for At-Risk First-Grade Readers

ERIC Educational Resources Information Center

Ashworth, Kristen E.

2012-01-01

The purposes of this study were to determine the effectiveness of a vocabulary intervention for first-grade students at risk for reading and language difficulties and to compare the results of a regression discontinuity design to those of an experimental design. The specific research questions were: (1) Do first-graders who are at risk of reading…

Bringing a Perspective from Outside the Field: A Commentary on Davis et al.'s (2010) Use of a Modified Regression Discontinuity Design to Evaluate a Gifted Program

ERIC Educational Resources Information Center

Adelson, Jill L.; Kelcey, Benjamin

2016-01-01

In this commentary of "Evaluating the Gifted Program of an Urban School District Using a Modified Regression Discontinuity Design" by Davis, Engberg, Epple, Sieg, and Zimmer, we examine the background of the study, critique the methods used, and discuss the results and implications. The study used a fuzzy regression discontinuity design…

Application of Regression-Discontinuity Analysis in Pharmaceutical Health Services Research

PubMed Central

Zuckerman, Ilene H; Lee, Euni; Wutoh, Anthony K; Xue, Zhenyi; Stuart, Bruce

2006-01-01

Objective To demonstrate how a relatively underused design, regression-discontinuity (RD), can provide robust estimates of intervention effects when stronger designs are impossible to implement. Data Sources/Study Setting Administrative claims from a Mid-Atlantic state Medicaid program were used to evaluate the effectiveness of an educational drug utilization review intervention. Study Design Quasi-experimental design. Data Collection/Extraction Methods A drug utilization review study was conducted to evaluate a letter intervention to physicians treating Medicaid children with potentially excessive use of short-acting β2-agonist inhalers (SAB). The outcome measure is change in seasonally-adjusted SAB use 5 months pre- and postintervention. To determine if the intervention reduced monthly SAB utilization, results from an RD analysis are compared to findings from a pretest–posttest design using repeated-measure ANOVA. Principal Findings Both analyses indicated that the intervention significantly reduced SAB use among the high users. Average monthly SAB use declined by 0.9 canisters per month (p<.001) according to the repeated-measure ANOVA and by 0.2 canisters per month (p<.001) from RD analysis. Conclusions Regression-discontinuity design is a useful quasi-experimental methodology that has significant advantages in internal validity compared to other pre–post designs when assessing interventions in which subjects' assignment is based on cutoff scores for a critical variable. PMID:16584464

Old age pension and intergenerational living arrangements: a regression discontinuity design

PubMed Central

2017-01-01

China launched a pension program for rural residents in 2009, now covering more than 300 million Chinese. This program offers a unique setting for studying the ageing population, given the rapidity of China’s population ageing, traditions of filial piety and co-residence, decreasing number of children, and dearth of formal social security, at a relatively low income level. This paper examines whether receipt of the old-age pension payment equips elderly parents and their adult children to live apart and whether parents substitute children’s time involved in instrumental support to them with service consumption. Employing a regression discontinuity design to a primary longitudinal survey conducted in Guizhou province of China, this paper overcomes challenges in the literature that households eligible for pension payment might be systematically different from ineligible households and that it is difficult to separate the effect of pension from that of age or cohort heterogeneity. Around the pension eligibility age cut-off, results reveal large and significant reduction in intergenerational co-residence of the extended family and increase in service consumption among elderly parents. PMID:29051720

Regression discontinuity design in criminal justice evaluation: an introduction and illustration.

PubMed

Rhodes, William; Jalbert, Sarah Kuck

2013-01-01

Corrections agencies frequently place offenders into risk categories, within which offenders receive different levels of supervision and programming. This supervision strategy is seldom evaluated but often can be through routine use of a regression discontinuity design (RDD). This article argues that RDD provides a rigorous and cost-effective method for correctional agencies to evaluate and improve supervision strategies and advocates for using RDD routinely in corrections administration. The objective is to better employ correctional resources. This article uses a Neyman-Pearson counterfactual framework to introduce readers to RDD, to provide intuition for why RDD should be used broadly, and to motivate a deeper reading into the methodology. The article also illustrates an application of RDD to evaluate an intensive supervision program for probationers. Application of the RDD, which requires basic knowledge of regressions and some special diagnostic tools, is within the competencies of many criminal justice evaluators. RDD is shown to be an effective strategy to identify the treatment effect in a community corrections agency using supervision that meets the necessary conditions for RDD. The article concludes with a critical review of how RDD compares to experimental methods to answer policy questions. The article recommends using RDD to evaluate whether differing levels of control and correction reduce criminal recidivism. It also advocates for routine use of RDD as an administrative tool to determine cut points used to assign offenders into different risk categories based on the offenders' risk scores.

Improving Balance in Regression Discontinuity Design by Matching: Estimating the Effect of Academic Probation after the First Year of College

ERIC Educational Resources Information Center

Chi, Olivia L.; Dow, Aaron W.

2014-01-01

This study focuses on how matching, a method of preprocessing data prior to estimation and analysis, can be used to reduce imbalance between treatment and control group in regression discontinuity design. To examine the effects of academic probation on student outcomes, researchers replicate and expand upon research conducted by Lindo, Sanders,…

An Empirical Comparison of Randomized Control Trials and Regression Discontinuity Estimations

ERIC Educational Resources Information Center

Barrera-Osorio, Felipe; Filmer, Deon; McIntyre, Joe

2014-01-01

Randomized controlled trials (RCTs) and regression discontinuity (RD) studies both provide estimates of causal effects. A major difference between the two is that RD only estimates local average treatment effects (LATE) near the cutoff point of the forcing variable. This has been cited as a drawback to RD designs (Cook & Wong, 2008).…

Estimating Causal Effects of Education Interventions Using a Two-Rating Regression Discontinuity Design: Lessons from a Simulation Study and an Application

ERIC Educational Resources Information Center

Porter, Kristin E.; Reardon, Sean F.; Unlu, Fatih; Bloom, Howard S.; Cimpian, Joseph R.

2017-01-01

A valuable extension of the single-rating regression discontinuity design (RDD) is a multiple-rating RDD (MRRDD). To date, four main methods have been used to estimate average treatment effects at the multiple treatment frontiers of an MRRDD: the "surface" method, the "frontier" method, the "binding-score" method, and…

Financial Aid and First-Year Collegiate GPA: A Regression Discontinuity Approach

ERIC Educational Resources Information Center

Curs, Bradley R.; Harper, Casandra E.

2012-01-01

Using a regression discontinuity design, we investigate whether a merit-based financial aid program has a causal effect on the first-year grade point average of first-time out-of-state freshmen at the University of Oregon. Our results indicate that merit-based financial aid has a positive and significant effect on first-year collegiate grade point…

Replicating Experimental Impact Estimates Using a Regression Discontinuity Approach. NCEE 2012-4025

ERIC Educational Resources Information Center

Gleason, Philip M.; Resch, Alexandra M.; Berk, Jillian A.

2012-01-01

This NCEE Technical Methods Paper compares the estimated impacts of an educational intervention using experimental and regression discontinuity (RD) study designs. The analysis used data from two large-scale randomized controlled trials--the Education Technology Evaluation and the Teach for America Study--to provide evidence on the performance of…

School Turnaround in North Carolina: A Regression Discontinuity Analysis. Working Paper 156

ERIC Educational Resources Information Center

Heissel, Jennifer A.; Ladd, Helen F.

2016-01-01

This paper examines the effect of school turnaround in North Carolina elementary and middle schools. Using a regression discontinuity design, we find that turnaround led to a drop in average school-level math and reading passing rates and an increased concentration of low-income students in treated schools. We use teacher survey data to examine…

Random Measurement Error Does Not Bias the Treatment Effect Estimate in the Regression-Discontinuity Design. II. When an Interaction Effect Is Present.

ERIC Educational Resources Information Center

Trochim, William M. K.; And Others

1991-01-01

The regression-discontinuity design involving a treatment interaction effect (TIE), pretest-posttest functional form specification, and choice of point-of-estimation of the TIE are examined. Formulas for controlling the magnitude of TIE in simulations can be used for simulating the randomized experimental case where estimation is not at the…

Evaluating effects of developmental education for college students using a regression discontinuity design.

PubMed

Moss, Brian G; Yeaton, William H

2013-10-01

Annually, American colleges and universities provide developmental education (DE) to millions of underprepared students; however, evaluation estimates of DE benefits have been mixed. Using a prototypic exemplar of DE, our primary objective was to investigate the utility of a replicative evaluative framework for assessing program effectiveness. Within the context of the regression discontinuity (RD) design, this research examined the effectiveness of a DE program for five, sequential cohorts of first-time college students. Discontinuity estimates were generated for individual terms and cumulatively, across terms. Participants were 3,589 first-time community college students. DE program effects were measured by contrasting both college-level English grades and a dichotomous measure of pass/fail, for DE and non-DE students. Parametric and nonparametric estimates of overall effect were positive for continuous and dichotomous measures of achievement (grade and pass/fail). The variability of program effects over time was determined by tracking results within individual terms and cumulatively, across terms. Applying this replication strategy, DE's overall impact was modest (an effect size of approximately .20) but quite consistent, based on parametric and nonparametric estimation approaches. A meta-analysis of five RD results yielded virtually the same estimate as the overall, parametric findings. Subset analysis, though tentative, suggested that males benefited more than females, while academic gains were comparable for different ethnicities. The cumulative, within-study comparison, replication approach offers considerable potential for the evaluation of new and existing policies, particularly when effects are relatively small, as is often the case in applied settings.

Using a Regression Discontinuity Design to Estimate the Impact of Placement Decisions in Developmental Math

ERIC Educational Resources Information Center

Melguizo, Tatiana; Bos, Johannes M.; Ngo, Federick; Mills, Nicholas; Prather, George

2016-01-01

This study evaluates the effectiveness of math placement policies for entering community college students on these students' academic success in math. We estimate the impact of placement decisions by using a discrete-time survival model within a regression discontinuity framework. The primary conclusion that emerges is that initial placement in a…

The Effect of Education on Old Age Cognitive Abilities: Evidence from a Regression Discontinuity Design*

PubMed Central

Banks, James; Mazzonna, Fabrizio

2011-01-01

In this paper we exploit the 1947 change to the minimum school-leaving age in England from 14 to 15, to evaluate the causal effect of a year of education on cognitive abilities at older ages. We use a regression discontinuity design analysis and find a large and significant effect of the reform on males’ memory and executive functioning at older ages, using simple cognitive tests from the English Longitudinal Survey on Ageing (ELSA) as our outcome measures. This result is particularly remarkable since the reform had a powerful and immediate effect on about half the population of 14-year-olds. We investigate and discuss the potential channels by which this reform may have had its effects, as well as carrying out a full set of sensitivity analyses and robustness checks. PMID:22611283

The regression discontinuity design showed to be a valid alternative to a randomized controlled trial for estimating treatment effects.

PubMed

Maas, Iris L; Nolte, Sandra; Walter, Otto B; Berger, Thomas; Hautzinger, Martin; Hohagen, Fritz; Lutz, Wolfgang; Meyer, Björn; Schröder, Johanna; Späth, Christina; Klein, Jan Philipp; Moritz, Steffen; Rose, Matthias

2017-02-01

To compare treatment effect estimates obtained from a regression discontinuity (RD) design with results from an actual randomized controlled trial (RCT). Data from an RCT (EVIDENT), which studied the effect of an Internet intervention on depressive symptoms measured with the Patient Health Questionnaire (PHQ-9), were used to perform an RD analysis, in which treatment allocation was determined by a cutoff value at baseline (PHQ-9 = 10). A linear regression model was fitted to the data, selecting participants above the cutoff who had received the intervention (n = 317) and control participants below the cutoff (n = 187). Outcome was PHQ-9 sum score 12 weeks after baseline. Robustness of the effect estimate was studied; the estimate was compared with the RCT treatment effect. The final regression model showed a regression coefficient of -2.29 [95% confidence interval (CI): -3.72 to -.85] compared with a treatment effect found in the RCT of -1.57 (95% CI: -2.07 to -1.07). Although the estimates obtained from two designs are not equal, their confidence intervals overlap, suggesting that an RD design can be a valid alternative for RCTs. This finding is particularly important for situations where an RCT may not be feasible or ethical as is often the case in clinical research settings. Copyright © 2016 Elsevier Inc. All rights reserved.

Examining the Association between School Context, Educational Capacity, and Student Achievement: A Regression Discontinuity Approach

ERIC Educational Resources Information Center

Moriyama, Karen Ito

2009-01-01

In this era of accountability, there is a need to fairly and accurately document the ways that educational systems contribute to student achievement. This study used the regression discontinuity design within a multilevel framework as an alternative approach to estimate school effectiveness by examining the effect of the value added to students'…

The Effects of School Wide Bonuses on Student Achievement: Regression Discontinuity Evidence from North Carolina

ERIC Educational Resources Information Center

Lauen, Douglas Lee

2011-01-01

This study examines the incentive effects of North Carolina's practice of awarding performance bonuses on test score achievement on the state tests. Bonuses were awarded based solely on whether a school exceeds a threshold on a continuous performance metric. The study uses a sharp regression discontinuity design, an approach with strong internal…

Inter-Method Reliability of School Effectiveness Measures: A Comparison of Value-Added and Regression Discontinuity Estimates

ERIC Educational Resources Information Center

Perry, Thomas

2017-01-01

Value-added (VA) measures are currently the predominant approach used to compare the effectiveness of schools. Recent educational effectiveness research, however, has developed alternative approaches including the regression discontinuity (RD) design, which also allows estimation of absolute school effects. Initial research suggests RD is a viable…

Why High-Order Polynomials Should Not Be Used in Regression Discontinuity Designs. NBER Working Paper No. 20405

ERIC Educational Resources Information Center

Gelman, Andrew; Imbens, Guido

2014-01-01

It is common in regression discontinuity analysis to control for high order (third, fourth, or higher) polynomials of the forcing variable. We argue that estimators for causal effects based on such methods can be misleading, and we recommend researchers do not use them, and instead use estimators based on local linear or quadratic polynomials or…

Gifted Identification and the Role of Gifted Education: A Commentary on "Evaluating the Gifted Program of an Urban School District Using a Modified Regression Discontinuity Design"

ERIC Educational Resources Information Center

Steenbergen-Hu, Saiying; Olszewski-Kubilius, Paula

2016-01-01

The article by Davis, Engberg, Epple, Sieg, and Zimmer (2010) represents one of the recent research efforts from economists in evaluating the impact of gifted programs. It can serve as a worked example of the implementation of the regression discontinuity (RD) design method in gifted education research. In this commentary, we first illustrate the…

Reducing Bias and Increasing Precision by Adding Either a Pretest Measure of the Study Outcome or a Nonequivalent Comparison Group to the Basic Regression Discontinuity Design: An Example from Education

ERIC Educational Resources Information Center

Tang, Yang; Cook, Thomas D.; Kisbu-Sakarya, Yasemin

2015-01-01

Regression discontinuity design (RD) has been widely used to produce reliable causal estimates. Researchers have validated the accuracy of RD design using within study comparisons (Cook, Shadish & Wong, 2008; Cook & Steiner, 2010; Shadish et al, 2011). Within study comparisons examines the validity of a quasi-experiment by comparing its…

The Impact of Letter Grades on Student Effort, Course Selection, and Major Choice: A Regression-Discontinuity Analysis

ERIC Educational Resources Information Center

Main, Joyce B.; Ost, Ben

2014-01-01

The authors apply a regression-discontinuity design to identify the causal impact of letter grades on student effort within a course, subsequent credit hours taken, and the probability of majoring in economics. Their methodology addresses key issues in identifying the causal impact of letter grades: correlation with unobservable factors, such as…

Updated Design Standards and Guidance from the What Works Clearinghouse: Regression Discontinuity Designs and Cluster Designs

ERIC Educational Resources Information Center

Cole, Russell; Deke, John; Seftor, Neil

2016-01-01

The What Works Clearinghouse (WWC) maintains design standards to identify rigorous, internally valid education research. As education researchers advance new methodologies, the WWC must revise its standards to include an assessment of the new designs. Recently, the WWC has revised standards for two emerging study designs: regression discontinuity…

Bayesian regression discontinuity designs: incorporating clinical knowledge in the causal analysis of primary care data.

PubMed

Geneletti, Sara; O'Keeffe, Aidan G; Sharples, Linda D; Richardson, Sylvia; Baio, Gianluca

2015-07-10

The regression discontinuity (RD) design is a quasi-experimental design that estimates the causal effects of a treatment by exploiting naturally occurring treatment rules. It can be applied in any context where a particular treatment or intervention is administered according to a pre-specified rule linked to a continuous variable. Such thresholds are common in primary care drug prescription where the RD design can be used to estimate the causal effect of medication in the general population. Such results can then be contrasted to those obtained from randomised controlled trials (RCTs) and inform prescription policy and guidelines based on a more realistic and less expensive context. In this paper, we focus on statins, a class of cholesterol-lowering drugs, however, the methodology can be applied to many other drugs provided these are prescribed in accordance to pre-determined guidelines. Current guidelines in the UK state that statins should be prescribed to patients with 10-year cardiovascular disease risk scores in excess of 20%. If we consider patients whose risk scores are close to the 20%  risk score threshold, we find that there is an element of random variation in both the risk score itself and its measurement. We can therefore consider the threshold as a randomising device that assigns statin prescription to individuals just above the threshold and withholds it from those just below. Thus, we are effectively replicating the conditions of an RCT in the area around the threshold, removing or at least mitigating confounding. We frame the RD design in the language of conditional independence, which clarifies the assumptions necessary to apply an RD design to data, and which makes the links with instrumental variables clear. We also have context-specific knowledge about the expected sizes of the effects of statin prescription and are thus able to incorporate this into Bayesian models by formulating informative priors on our causal parameters. © 2015 The

To Leave or Not to Leave? A Regression Discontinuity Analysis of the Impact of Failing the High School Exit Exam

ERIC Educational Resources Information Center

Ou, Dongshu

2010-01-01

The high school exit exam (HSEE) is rapidly becoming a standardized assessment procedure for educational accountability in the United States. I use a unique, state-specific dataset to identify the effects of failing the HSEE on the likelihood of dropping out of high school based on a regression discontinuity design. The analysis shows that…

Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design.

PubMed

Bakolis, Ioannis; Kelly, Ruth; Fecht, Daniela; Best, Nicky; Millett, Christopher; Garwood, Kevin; Elliott, Paul; Hansell, Anna L; Hodgson, Susan

2016-11-01

Environmental tobacco smoke has an adverse association with preterm birth and birth weight. England introduced a new law to make virtually all enclosed public places and workplaces smoke free on July 1, 2007. We investigated the effect of smoke-free legislation on birth outcomes in England using Hospital Episode Statistics (HES) maternity data. We used regression discontinuity, a quasi-experimental study design, which can facilitate valid causal inference, to analyze short-term effects of smoke-free legislation on birth weight, low birth weight, gestational age, preterm birth, and small for gestational age. We analyzed 1,800,906 pregnancies resulting in singleton live-births in England between 1 January 2005 and 31 December 2009. In the 1 to 5 months following the introduction of the smoke-free legislation, for those entering their third trimester, the risk of low birth weight decreased by between 8% (95% confidence interval [CI]: 4%, 12%) and 14% (95% CI: 5%, 23%), very low birth weight between 28% (95% CI: 19%, 36%) and 32% (95% CI: 21%, 41%), preterm birth between 4% (95% CI: 1%, 8%) and 9% (95% CI: 2%, 16%), and small for gestational age between 5% (95% CI: 2%, 8%) and 9% (95% CI: 2%, 15%). The estimated impact of the smoke-free legislation varied by maternal age, deprivation, ethnicity, and region. The introduction of smoke-free legislation in England had an immediate estimated beneficial impact on birth outcomes overall, although we did not observe improvements across all age, ethnic, or deprivation groups.See video abstract at http://links.lww.com/EDE/B85.

Strategies for evaluating the assumptions of the regression discontinuity design: a case study using a human papillomavirus vaccination programme.

PubMed

Smith, Leah M; Lévesque, Linda E; Kaufman, Jay S; Strumpf, Erin C

2017-06-01

The regression discontinuity design (RDD) is a quasi-experimental approach used to avoid confounding bias in the assessment of new policies and interventions. It is applied specifically in situations where individuals are assigned to a policy/intervention based on whether they are above or below a pre-specified cut-off on a continuously measured variable, such as birth date, income or weight. The strength of the design is that, provided individuals do not manipulate the value of this variable, assignment to the policy/intervention is considered as good as random for individuals close to the cut-off. Despite its popularity in fields like economics, the RDD remains relatively unknown in epidemiology where its application could be tremendously useful. In this paper, we provide a practical introduction to the RDD for health researchers, describe four empirically testable assumptions of the design and offer strategies that can be used to assess whether these assumptions are met in a given study. For illustrative purposes, we implement these strategies to assess whether the RDD is appropriate for a study of the impact of human papillomavirus vaccination on cervical dysplasia. We found that, whereas the assumptions of the RDD were generally satisfied in our study context, birth timing had the potential to confound our effect estimate in an unexpected way and therefore needed to be taken into account in the analysis. Our findings underscore the importance of assessing the validity of the assumptions of this design, testing them when possible and making adjustments as necessary to support valid causal inference. © The Author 2016. Published by Oxford University Press on behalf of the International Epidemiological Association

What Happens to Students Placed into Developmental Education? A Meta-Analysis of Regression Discontinuity Studies

ERIC Educational Resources Information Center

Valentine, Jeffrey C.; Konstantopoulos, Spyros; Goldrick-Rab, Sara

2017-01-01

This article reports a systematic review and meta-analysis of studies that use regression discontinuity to examine the effects of placement into developmental education. Results suggest that placement into developmental education is associated with effects that are negative, statistically significant, and substantively large for three outcomes:…

Is There Evidence for Systematic Upcoding of ASA Physical Status Coincident with Payer Incentives? A Regression Discontinuity Analysis of the National Anesthesia Clinical Outcomes Registry.

PubMed

Schonberger, Robert B; Dutton, Richard P; Dai, Feng

2016-01-01

Modifications in physician billing patterns have been shown to occur in response to payer incentives, but the phenomenon remains largely unexplored in billing for anesthesia services. Within the field of anesthesiology, Medicare's policy not to provide additional reimbursement for higher ASA physical status scores contrasts with the practices of most private payers, and this pattern of reimbursement introduces a change in billing incentives once patients attain Medicare eligibility. We hypothesized that, coincident with the onset of widespread Medicare eligibility at age 65 years, a discontinuity in reported ASA physical status scores would be observed after controlling for the underlying trend of increasing ASA physical status scores with age. This phenomenon would manifest as a pattern of upcoding of ASA physical status scores for patients younger than 65 years that would become less common in patients age 65 years and older. Using data on age, sex, ASA physical status scores, and type of surgery from the National Anesthesia Clinical Outcomes Registry, we used a quasi-experimental regression discontinuity design to analyze whether there was evidence for a discontinuity in reported ASA physical status scores occurring at age 65 years for the nondeferrable anesthesia services accompanying hip, femur, or lower leg fracture repair. A total of 49,850 records were analyzed. In models designed to detect regression discontinuity at 65 years of age, neither the binary variable "age ≥ 65" nor the interaction term of age × age ≥ 65 was a statistically significant predictor of the outcome of ASA physical status score. The statistical inference was unchanged when ASA physical status scores were reclassified as a binary outcome (I-II vs III-V) and when different bandwidths around age 65 years were used. To test the validity of our study design for detecting regression discontinuity, simulations of the occurrence of deliberate upcoding of ASA physical status scores

The Impact of the Texas Top 10 Percent Law on College Enrollment: A Regression Discontinuity Approach

ERIC Educational Resources Information Center

Niu, Sunny Xinchun; Tienda, Marta

2010-01-01

We use regression discontinuity methods on a representative survey of Texas high school seniors to discern the impact on flagship-enrollment behavior of the Texas top 10 percent law, which guarantees admission to any Texas public university to students who graduate in the top decile of their class. By comparing students at and immediately below…

Learning from failure - rationale and design for a study about discontinuation of randomized trials (DISCO study)

PubMed Central

2012-01-01

Background Randomized controlled trials (RCTs) may be discontinued because of apparent harm, benefit, or futility. Other RCTs are discontinued early because of insufficient recruitment. Trial discontinuation has ethical implications, because participants consent on the premise of contributing to new medical knowledge, Research Ethics Committees (RECs) spend considerable effort reviewing study protocols, and limited resources for conducting research are wasted. Currently, little is known regarding the frequency and characteristics of discontinued RCTs. Methods/Design Our aims are, first, to determine the prevalence of RCT discontinuation for specific reasons; second, to determine whether the risk of RCT discontinuation for specific reasons differs between investigator- and industry-initiated RCTs; third, to identify risk factors for RCT discontinuation due to insufficient recruitment; fourth, to determine at what stage RCTs are discontinued; and fifth, to examine the publication history of discontinued RCTs. We are currently assembling a multicenter cohort of RCTs based on protocols approved between 2000 and 2002/3 by 6 RECs in Switzerland, Germany, and Canada. We are extracting data on RCT characteristics and planned recruitment for all included protocols. Completion and publication status is determined using information from correspondence between investigators and RECs, publications identified through literature searches, or by contacting the investigators. We will use multivariable regression models to identify risk factors for trial discontinuation due to insufficient recruitment. We aim to include over 1000 RCTs of which an anticipated 150 will have been discontinued due to insufficient recruitment. Discussion Our study will provide insights into the prevalence and characteristics of RCTs that were discontinued. Effective recruitment strategies and the anticipation of problems are key issues in the planning and evaluation of trials by investigators, Clinical

Effectiveness of a low-intensity telephone counselling intervention on an untreated metabolic syndrome detected by national population screening in Korea: a non-randomised study using regression discontinuity design

PubMed Central

Yi, Sang-Wook; Shin, Soon-Ae; Lee, Youn-Jung

2015-01-01

Objective Whether low-intensity telephone-counselling interventions can improve cardiometabolic risk factors in screen-detected people with metabolic syndrome (MetS) is unclear. The aim of this study was to evaluate the effectiveness of a low-intensity, telephone-counselling programme on MetS implemented by the National Health Insurance Service (NHIS) of Korea using regression discontinuity design. Design A nationwide non-randomised intervention study with a regression discontinuity design. A retrospective analysis using data from NHIS. Setting NHIS, Korea from January 2011 to June 2013. Participants 5 378 558 beneficiaries with one or more MetS components by NHIS criteria detected by population screening were enrolled in the NHIS MetS Management Programme in 2012. Of these, 1 147 695 underwent annual follow-up examinations until June 2013 (‘control group’ which received control intervention, n=855 870; ‘eligible group’ which was eligible for counselling, n=291 825; ‘intervention group’ which participated in telephone counselling among eligible groups, n=23 968). Main outcome measures Absolute changes in MetS components, weight and body mass index (BMI) were analysed. Multiple regression analyses were applied using the analysis of covariance model (baseline measurements as covariates). Results Low-intensity telephone counselling was associated with decreased systolic BP (−0.85 mm Hg, 95% CI −1.02 to −0.68), decreased diastolic BP (−0.63 mm Hg, −95% CI −0.75 to −0.50), decreased triglyceride (−1.57 mg/dL, 95% CI −2.89 to −0.25), reduced waist circumference (−0.09 cm, 95% CI −0.16 to −0.02), reduced weight (−0.19 kg, 95% CI −0.24 to −0.15) and reduced BMI (−0.07 kg/m2, 95% CI −0.09 to −0.05), when comparing the intervention and control groups. When individuals with low high-density lipoprotein cholesterol were analysed, the intervention was also associated with increased HDL cholesterol

Effectiveness of a low-intensity telephone counselling intervention on an untreated metabolic syndrome detected by national population screening in Korea: a non-randomised study using regression discontinuity design.

PubMed

Yi, Sang-Wook; Shin, Soon-Ae; Lee, Youn-Jung

2015-07-10

Whether low-intensity telephone-counselling interventions can improve cardiometabolic risk factors in screen-detected people with metabolic syndrome (MetS) is unclear. The aim of this study was to evaluate the effectiveness of a low-intensity, telephone-counselling programme on MetS implemented by the National Health Insurance Service (NHIS) of Korea using regression discontinuity design. A nationwide non-randomised intervention study with a regression discontinuity design. A retrospective analysis using data from NHIS. NHIS, Korea from January 2011 to June 2013. 5,378,558 beneficiaries with one or more MetS components by NHIS criteria detected by population screening were enrolled in the NHIS MetS Management Programme in 2012. Of these, 1,147,695 underwent annual follow-up examinations until June 2013 ('control group' which received control intervention, n=855,870; 'eligible group' which was eligible for counselling, n=291,825; 'intervention group' which participated in telephone counselling among eligible groups, n=23,968). Absolute changes in MetS components, weight and body mass index (BMI) were analysed. Multiple regression analyses were applied using the analysis of covariance model (baseline measurements as covariates). Low-intensity telephone counselling was associated with decreased systolic BP (-0.85 mm Hg, 95% CI -1.02 to -0.68), decreased diastolic BP (-0.63 mm Hg, -95% CI -0.75 to -0.50), decreased triglyceride (-1.57 mg/dL, 95% CI -2.89 to -0.25), reduced waist circumference (-0.09 cm, 95% CI -0.16 to -0.02), reduced weight (-0.19 kg, 95% CI -0.24 to -0.15) and reduced BMI (-0.07 kg/m(2), 95% CI -0.09 to -0.05), when comparing the intervention and control groups. When individuals with low high-density lipoprotein cholesterol were analysed, the intervention was also associated with increased HDL cholesterol (0.90 mg/dL, 95% CI 0.51 to 1.29). Low-intensity telephone counselling programmes could yield improvements in the following year

Optimal Design for Regression Discontinuity Studies with Clustering

ERIC Educational Resources Information Center

Rhoads, Christopher; Dye, Charles

2014-01-01

Recent years have seen an increased interest in quantitative educational research studies that use random assignment (RA) to evaluate the causal impacts of educational interventions (Angrist, 2004). The multi-level structure of the public education system in the United States often leads to experimental designs where naturally occurring clusters…

The Impact of Being Labeled as a Persistently Lowest Achieving School: Regression Discontinuity Evidence on Consequential School Labeling

ERIC Educational Resources Information Center

Saw, Guan; Schneider, Barbara; Frank, Kenneth; Chen, I-Chien; Keesler, Venessa; Martineau, Joseph

2017-01-01

Since the No Child Left Behind Act was enacted, grading and labeling of schools as low performing have been increasingly used as means to incentivize failing schools to raise student achievement. Using statewide high school data from Michigan, our regression discontinuity analyses show that the bottom 5% of schools identified as persistently…

The price sensitivity of Medicare beneficiaries: a regression discontinuity approach.

PubMed

Buchmueller, Thomas C; Grazier, Kyle; Hirth, Richard A; Okeke, Edward N

2013-01-01

We use 4 years of data from the retiree health benefits program of the University of Michigan to estimate the effect of price on the health plan choices of Medicare beneficiaries. During the period of our analysis, changes in the University's premium contribution rules led to substantial price changes. A key feature of this 'natural experiment' is that individuals who had retired before a certain date were exempted from having to pay any premium contributions. This 'grandfathering' creates quasi-experimental variation that is ideal for estimating the effect of price. Using regression discontinuity methods, we compare the plan choices of individuals who retired just after the grandfathering cutoff date and were therefore exposed to significant price changes to the choices of a 'control group' of individuals who retired just before that date and therefore did not experience the price changes. The results indicate a statistically significant effect of price, with a $10 increase in monthly premium contributions leading to a 2 to 3 percentage point decrease in a plan's market share. Copyright © 2012 John Wiley & Sons, Ltd.

Discontinuous Observers Design for Finite-Time Consensus of Multiagent Systems With External Disturbances.

PubMed

Liu, Xiaoyang; Ho, Daniel W C; Cao, Jinde; Xu, Wenying

This brief investigates the problem of finite-time robust consensus (FTRC) for second-order nonlinear multiagent systems with external disturbances. Based on the global finite-time stability theory of discontinuous homogeneous systems, a novel finite-time convergent discontinuous disturbed observer (DDO) is proposed for the leader-following multiagent systems. The states of the designed DDO are then used to design the control inputs to achieve the FTRC of nonlinear multiagent systems in the presence of bounded disturbances. The simulation results are provided to validate the effectiveness of these theoretical results.This brief investigates the problem of finite-time robust consensus (FTRC) for second-order nonlinear multiagent systems with external disturbances. Based on the global finite-time stability theory of discontinuous homogeneous systems, a novel finite-time convergent discontinuous disturbed observer (DDO) is proposed for the leader-following multiagent systems. The states of the designed DDO are then used to design the control inputs to achieve the FTRC of nonlinear multiagent systems in the presence of bounded disturbances. The simulation results are provided to validate the effectiveness of these theoretical results.

Discontinuation, Efficacy, and Safety of Cholinesterase Inhibitors for Alzheimer’s Disease: a Meta-Analysis and Meta-Regression of 43 Randomized Clinical Trials Enrolling 16 106 Patients

PubMed Central

Blanco-Silvente, Lídia; Saez, Marc; Barceló, Maria Antònia; Garre-Olmo, Josep; Vilalta-Franch, Joan; Capellà, Dolors

2017-01-01

Abstract Background: We investigated the effect of cholinesterase inhibitors on all-cause discontinuation, efficacy and safety, and the effects of study design-, intervention-, and patient-related covariates on the risk-benefit of cholinesterase inhibitors for Alzheimer’s disease. Methods: A systematic review and meta-analysis of randomized placebo-controlled clinical trials comparing cholinesterase inhibitors and placebo was performed. The effect of covariates on study outcomes was analysed by means of meta-regression using a Bayesian framework. Results: Forty-three randomized placebo-controlled clinical trials involving 16106 patients were included. All-cause discontinuation was higher with cholinesterase inhibitors (OR = 1.66), as was discontinuation due to adverse events (OR=1.75). Cholinesterase inhibitors improved cognitive function (standardized mean difference = 0.38), global symptomatology (standardized mean difference=0.28) and functional capacity (standardized mean difference=0.16) but not neuropsychiatric symptoms. Rivastigmine was associated with a poorer outcome on all-cause discontinuation (Diff OR = 1.66) and donepezil with a higher efficacy on global change (Diff standardized mean difference = 0.41). The proportion of patients with serious adverse events decreased with age (Diff OR = -0.09). Mortality was lower with cholinesterase inhibitors than with placebo (OR = 0.65). Conclusion: While cholinesterase inhibitors show a poor risk-benefit relationship as indicated by mild symptom improvement and a higher than placebo all-cause discontinuation, a reduction of mortality was suggested. Intervention- and patient-related factors modify the effect of cholinesterase inhibitors in patients with Alzheimer’s disease. PMID:28201726

Discontinuation, Efficacy, and Safety of Cholinesterase Inhibitors for Alzheimer's Disease: a Meta-Analysis and Meta-Regression of 43 Randomized Clinical Trials Enrolling 16 106 Patients.

PubMed

Blanco-Silvente, Lídia; Castells, Xavier; Saez, Marc; Barceló, Maria Antònia; Garre-Olmo, Josep; Vilalta-Franch, Joan; Capellà, Dolors

2017-07-01

We investigated the effect of cholinesterase inhibitors on all-cause discontinuation, efficacy and safety, and the effects of study design-, intervention-, and patient-related covariates on the risk-benefit of cholinesterase inhibitors for Alzheimer's disease. A systematic review and meta-analysis of randomized placebo-controlled clinical trials comparing cholinesterase inhibitors and placebo was performed. The effect of covariates on study outcomes was analysed by means of meta-regression using a Bayesian framework. Forty-three randomized placebo-controlled clinical trials involving 16106 patients were included. All-cause discontinuation was higher with cholinesterase inhibitors (OR = 1.66), as was discontinuation due to adverse events (OR=1.75). Cholinesterase inhibitors improved cognitive function (standardized mean difference = 0.38), global symptomatology (standardized mean difference=0.28) and functional capacity (standardized mean difference=0.16) but not neuropsychiatric symptoms. Rivastigmine was associated with a poorer outcome on all-cause discontinuation (Diff OR = 1.66) and donepezil with a higher efficacy on global change (Diff standardized mean difference = 0.41). The proportion of patients with serious adverse events decreased with age (Diff OR = -0.09). Mortality was lower with cholinesterase inhibitors than with placebo (OR = 0.65). While cholinesterase inhibitors show a poor risk-benefit relationship as indicated by mild symptom improvement and a higher than placebo all-cause discontinuation, a reduction of mortality was suggested. Intervention- and patient-related factors modify the effect of cholinesterase inhibitors in patients with Alzheimer's disease. © The Author 2017. Published by Oxford University Press on behalf of CINP.

Statistical Power for the Comparative Regression Discontinuity Design With a Pretest No-Treatment Control Function: Theory and Evidence From the National Head Start Impact Study.

PubMed

Tang, Yang; Cook, Thomas D

2018-01-01

The basic regression discontinuity design (RDD) has less statistical power than a randomized control trial (RCT) with the same sample size. Adding a no-treatment comparison function to the basic RDD creates a comparative RDD (CRD); and when this function comes from the pretest value of the study outcome, a CRD-Pre design results. We use a within-study comparison (WSC) to examine the power of CRD-Pre relative to both basic RDD and RCT. We first build the theoretical foundation for power in CRD-Pre, then derive the relevant variance formulae, and finally compare them to the theoretical RCT variance. We conclude from this theoretical part of this article that (1) CRD-Pre's power gain depends on the partial correlation between the pretest and posttest measures after conditioning on the assignment variable, (2) CRD-Pre is less responsive than basic RDD to how the assignment variable is distributed and where the cutoff is located, and (3) under a variety of conditions, the efficiency of CRD-Pre is very close to that of the RCT. Data from the National Head Start Impact Study are then used to construct RCT, RDD, and CRD-Pre designs and to compare their power. The empirical results indicate (1) a high level of correspondence between the predicted and obtained power results for RDD and CRD-Pre relative to the RCT, and (2) power levels in CRD-Pre and RCT that are very close. The study is unique among WSCs for its focus on the correspondence between RCT and observational study standard errors rather than means.

Regression Discontinuity and Randomized Controlled Trial Estimates: An Application to The Mycotic Ulcer Treatment Trials.

PubMed

Oldenburg, Catherine E; Venkatesh Prajna, N; Krishnan, Tiruvengada; Rajaraman, Revathi; Srinivasan, Muthiah; Ray, Kathryn J; O'Brien, Kieran S; Glymour, M Maria; Porco, Travis C; Acharya, Nisha R; Rose-Nussbaumer, Jennifer; Lietman, Thomas M

2018-08-01

We compare results from regression discontinuity (RD) analysis to primary results of a randomized controlled trial (RCT) utilizing data from two contemporaneous RCTs for treatment of fungal corneal ulcers. Patients were enrolled in the Mycotic Ulcer Treatment Trials I and II (MUTT I & MUTT II) based on baseline visual acuity: patients with acuity ≤ 20/400 (logMAR 1.3) enrolled in MUTT I, and >20/400 in MUTT II. MUTT I investigated the effect of topical natamycin versus voriconazole on best spectacle-corrected visual acuity. MUTT II investigated the effect of topical voriconazole plus placebo versus topical voriconazole plus oral voriconazole. We compared the RD estimate (natamycin arm of MUTT I [N = 162] versus placebo arm of MUTT II [N = 54]) to the RCT estimate from MUTT I (topical natamycin [N = 162] versus topical voriconazole [N = 161]). In the RD, patients receiving natamycin had mean improvement of 4-lines of visual acuity at 3 months (logMAR -0.39, 95% CI: -0.61, -0.17) compared to topical voriconazole plus placebo, and 2-lines in the RCT (logMAR -0.18, 95% CI: -0.30, -0.05) compared to topical voriconazole. The RD and RCT estimates were similar, although the RD design overestimated effects compared to the RCT.

Predictors of discontinuation of antipsychotic medication and subsequent outcomes in the European First Episode Schizophrenia Trial (EUFEST).

PubMed

Landolt, Karin; Rössler, Wulf; Ajdacic-Gross, Vladeta; Derks, Eske M; Libiger, Jan; Kahn, René S; Fleischhacker, W Wolfgang

2016-04-01

This study had two aims: to describe patients suffering from first-episode schizophrenia who had stopped taking any antipsychotic medication, and to gain information on the predictors of successful discontinuation. We investigated data from the European First Episode Schizophrenia Trial (EUFEST). From the 325 patients included, 15.7% discontinued all antipsychotic medication. In a first analysis, clinical and sociodemographical predictors of discontinuing any antipsychotic medication were identified, using Cox regression. In the second analysis, logistic regression was used to determine variables associated with those patients who had stopped taking antipsychotic medication and had a favourable outcome, i.e., successful discontinuation. A good outcome was defined as a) having had no relapse within the whole observation period (80.6%), and b) having had no relapse and symptomatic remission at 12-month-follow-up (37.2%). Cox regression revealed that a higher proportion of patients from Western European countries and Israel stopped antipsychotic medication than from Central and Eastern European countries, that relapse was associated with discontinuation, and that discontinuers had lower compliance and higher quality of life. Predictors of successful discontinuation differed with the outcome definition used. Using definition b), successful discontinuers had a better baseline prognosis and better baseline social integration. Using definition a), successful discontinuers more often were from Western European countries. Region and clinical factors were associated with discontinuation. Prognosis and social integration played an important role in predicting successful discontinuation. As this study had several limitations, for example the observational design regarding discontinuation, further studies are needed to identify predictors of successful discontinuation. Copyright © 2016 Elsevier B.V. All rights reserved.

Tracing the Effects of Guaranteed Admission through the College Process: Regression Discontinuity Evidence from the Texas 10% Plan◆

PubMed Central

Fletcher, Jason M.; Mayer, Adalbert

2012-01-01

The Texas 10% law states that students who graduated among the top 10% of their high school class are guaranteed admission to public universities in Texas. We estimate the causal effects of this admissions guarantee on a sequence of connected decisions: students’ application behavior, admission decisions by the university, students’ enrollment choices conditional on admission; as well as the resulting college achievement. We identify these effects by comparing students just above and just below the top 10% rank cutoff. While this design is in the spirit of a regression discontinuity, we note important differences in approach and interpretation. We find that students react to incentives created by the admissions guarantee - for example, by reducing applications to competing private universities. The results also suggest that the effects of the admissions guarantee depend on the university and the type of students it attracts, and that the law is binding and alters the decisions of the admissions committees. We find little evidence that the law increases diversity or leads to meaningful mismatch for the marginal student admitted. PMID:24610997

Optimal Design for Two-Level Random Assignment and Regression Discontinuity Studies

ERIC Educational Resources Information Center

Rhoads, Christopher H.; Dye, Charles

2016-01-01

An important concern when planning research studies is to obtain maximum precision of an estimate of a treatment effect given a budget constraint. When research designs have a "multilevel" or "hierarchical" structure changes in sample size at different levels of the design will impact precision differently. Furthermore, there…

Relative Age in School and Suicide among Young Individuals in Japan: A Regression Discontinuity Approach.

PubMed

Matsubayashi, Tetsuya; Ueda, Michiko

2015-01-01

Evidence collected in many parts of the world suggests that, compared to older students, students who are relatively younger at school entry tend to have worse academic performance and lower levels of income. This study examined how relative age in a grade affects suicide rates of adolescents and young adults between 15 and 25 years of age using data from Japan. We examined individual death records in the Vital Statistics of Japan from 1989 to 2010. In contrast to other countries, late entry to primary school is not allowed in Japan. We took advantage of the school entry cutoff date to implement a regression discontinuity (RD) design, assuming that the timing of births around the school entry cutoff date was randomly determined and therefore that individuals who were born just before and after the cutoff date have similar baseline characteristics. We found that those who were born right before the school cutoff day and thus youngest in their cohort have higher mortality rates by suicide, compared to their peers who were born right after the cutoff date and thus older. We also found that those with relative age disadvantage tend to follow a different career path than those with relative age advantage, which may explain their higher suicide mortality rates. Relative age effects have broader consequences than was previously supposed. This study suggests that policy intervention that alleviates the relative age effect can be important.

Discontinuation among University Students in Southern Thailand

ERIC Educational Resources Information Center

Sittichai, Ruthaychonnee; Tongkumchum, Phattrawan; McNeil, Nittaya

2009-01-01

This study uses a statistical model to account for the pattern of discontinuation of university study at Pattani campus of Prince of Songkla University (PSU) in southern Thailand. University records for 11,408 bachelor degree students enrolled between 1999 and 2006 were used. Discontinuation rates were analyzed by using a logistic regression model…

Technological Discontinuities and Dominant Designs: A Cyclical Model of Technological Change.

ERIC Educational Resources Information Center

Anderson, Philip; Tushman, Michael L.

1990-01-01

Based on longitudinal studies of the cement, glass, and minicomputer industries, this article proposes a technological change model in which a technological breakthrough, or discontinuity, initiates an era of intense technical variation and selection, culminating in a single dominant design and followed by a period of incremental technical…

Real-world data to assess changes in low-density lipoprotein cholesterol and predicted cardiovascular risk after ezetimibe discontinuation post reporting of the Ezetimibe and Simvastatin in Hypercholesterolemia Enhances Atherosclerosis Regression trial.

PubMed

Bays, Harold E; Patel, Mehul D; Mavros, Panagiotis; Ramey, Dena R; Tomassini, Joanne E; Tershakovec, Andrew M; Baxter, Carl A

The 2008 Ezetimibe and Simvastatin in Hypercholesterolemia Enhances Atherosclerosis Regression (ENHANCE) study demonstrated ezetimibe + simvastatin vs simvastatin alone had a neutral effect on the surrogate endpoint of carotid intima-media thickness. Subsequent media portrayal of the study prompted ezetimibe discontinuation in many patients. The objective of the study was to assess the impact of ENHANCE reporting on ezetimibe discontinuation, low-density lipoprotein cholesterol (LDL-C) changes, and potential cardiovascular disease (CVD) risk. This analysis used claims data in a retrospective, observational study of patients receiving ezetimibe + statin and compared LDL-C for patients who discontinued ezetimibe (n = 970) vs those who continued ezetimibe + statins (n = 3706) after ENHANCE results disclosure. Change in relative CVD risk was estimated from the absolute LDL-C difference between groups per the Cholesterol Treatment Trialists' meta-analysis of statin trials. The rate of ezetimibe discontinuation was 2% in the 6 months before and 21% in the 6 months after reporting of ENHANCE results. Among patients who ultimately discontinued vs continued ezetimibe, respective mean LDL-C levels were 79.8 and 78.3 mg/dL 6 months before reporting of the ENHANCE results and 93.5 and 78.1 mg/dL 6 months after reporting of ENHANCE. Predictive application of the Cholesterol Treatment Trialists' meta-analysis suggested the 13.9 mg/dL increase in mean LDL-C translated to a 9.4% increase in relative CVD risk for those who discontinued ezetimibe. After reporting of the neutral ENHANCE results, ezetimibe discontinuation rate increased, LDL-C levels increased, and predicted CVD risk increased among those who discontinued ezetimibe. Characterization of clinical outcomes regarding lipid-altering agents based on surrogate biomarker studies not designed to assess CVD outcomes may be misleading, potentially placing patients at increased CVD risk. Copyright © 2017

Numerical studies of the thermal design sensitivity calculation for a reaction-diffusion system with discontinuous derivatives

NASA Technical Reports Server (NTRS)

Hou, Jean W.; Sheen, Jeen S.

1987-01-01

The aim of this study is to find a reliable numerical algorithm to calculate thermal design sensitivities of a transient problem with discontinuous derivatives. The thermal system of interest is a transient heat conduction problem related to the curing process of a composite laminate. A logical function which can smoothly approximate the discontinuity is introduced to modify the system equation. Two commonly used methods, the adjoint variable method and the direct differentiation method, are then applied to find the design derivatives of the modified system. The comparisons of numerical results obtained by these two methods demonstrate that the direct differentiation method is a better choice to be used in calculating thermal design sensitivity.

High-School Exit Examinations and the Schooling Decisions of Teenagers: Evidence From Regression-Discontinuity Approaches

PubMed Central

Papay, John P.; Murnane, Richard J.; Willett, John B.

2014-01-01

We examine whether barely failing one or more state-mandated high school exit examinations in Massachusetts affects the probability that students enroll in college. We extend the exit examination literature in two ways. First, we explore longer term effects of failing these tests. We find that barely failing an exit examination, for students on the margin of passing, reduces the probability of college attendance several years after the test. Second, we explore potential interactions that arise because students must pass exit examinations in both mathematics and English language arts in order to graduate from high school. We adopt a variety of regression-discontinuity approaches to address situations where multiple variables assign individuals to a range of treatments; some of these approaches enable us to examine whether the effect of barely failing one examination depends on student performance on the other. We document the range of causal effects estimated by each approach. We argue that each approach presents opportunities and limitations for making causal inferences in such situations and that the choice of approach should match the question of interest. PMID:25606065

Quasi-Experimental Designs for Causal Inference

ERIC Educational Resources Information Center

Kim, Yongnam; Steiner, Peter

2016-01-01

When randomized experiments are infeasible, quasi-experimental designs can be exploited to evaluate causal treatment effects. The strongest quasi-experimental designs for causal inference are regression discontinuity designs, instrumental variable designs, matching and propensity score designs, and comparative interrupted time series designs. This…

Evaluation of Pump Discontinuation and Associated Factors in the T1D Exchange Clinic Registry

PubMed Central

Wong, Jenise C.; Boyle, Claire; DiMeglio, Linda A.; Mastrandrea, Lucy D.; Abel, Kimber-Lee; Cengiz, Eda; Cemeroglu, Pinar A.; Aleppo, Grazia; Largay, Joseph F.; Foster, Nicole C.; Beck, Roy W.; Adi, Saleh

2017-01-01

Background: The objectives of this study were to examine factors associated with insulin pump discontinuation among children and adults followed longitudinally for 1 year in the multicenter T1D Exchange clinic registry, and to provide participant-reported reasons for stopping pump therapy. Methods: We longitudinally followed 8935 participants of all ages using an insulin pump at the time of registry enrollment. Logistic regressions were used to identify demographic and clinical factors associated with pump discontinuation. Pump discontinuation was self-reported by participants on a first annual follow-up survey. Results: The overall frequency of pump discontinuation was 3%. Discontinuation was higher in adolescents (4%) and young adults (4%) than in younger children (3%) or older adults (1%). In multivariate analysis of children between 6 and <13 and 13 and <18 years, participants who discontinued pump use were more likely to have higher HbA1c levels at baseline (adjusted P < .001 for both). The top participant-reported reasons for discontinuing the pump included problems with wearability (57%), disliking the pump or feeling anxious (44%), and problems with glycemic control (30%). Conclusions: In T1D Exchange registry participants, insulin pump discontinuation is uncommon, but more prevalent among adolescents and young adults, and youth with poor glycemic control. Given the known benefits of pump therapy, these populations should be targeted for support and education on troubleshooting pump use. Common reasons for discontinuation should also be considered in future device design and technological improvement. PMID:27595711

Evaluation of Pump Discontinuation and Associated Factors in the T1D Exchange Clinic Registry.

PubMed

Wong, Jenise C; Boyle, Claire; DiMeglio, Linda A; Mastrandrea, Lucy D; Abel, Kimber-Lee; Cengiz, Eda; Cemeroglu, Pinar A; Aleppo, Grazia; Largay, Joseph F; Foster, Nicole C; Beck, Roy W; Adi, Saleh

2017-03-01

The objectives of this study were to examine factors associated with insulin pump discontinuation among children and adults followed longitudinally for 1 year in the multicenter T1D Exchange clinic registry, and to provide participant-reported reasons for stopping pump therapy. We longitudinally followed 8935 participants of all ages using an insulin pump at the time of registry enrollment. Logistic regressions were used to identify demographic and clinical factors associated with pump discontinuation. Pump discontinuation was self-reported by participants on a first annual follow-up survey. The overall frequency of pump discontinuation was 3%. Discontinuation was higher in adolescents (4%) and young adults (4%) than in younger children (3%) or older adults (1%). In multivariate analysis of children between 6 and <13 and 13 and <18 years, participants who discontinued pump use were more likely to have higher HbA1c levels at baseline (adjusted P < .001 for both). The top participant-reported reasons for discontinuing the pump included problems with wearability (57%), disliking the pump or feeling anxious (44%), and problems with glycemic control (30%). In T1D Exchange registry participants, insulin pump discontinuation is uncommon, but more prevalent among adolescents and young adults, and youth with poor glycemic control. Given the known benefits of pump therapy, these populations should be targeted for support and education on troubleshooting pump use. Common reasons for discontinuation should also be considered in future device design and technological improvement.

Graphical Models for Quasi-Experimental Designs

ERIC Educational Resources Information Center

Steiner, Peter M.; Kim, Yongnam; Hall, Courtney E.; Su, Dan

2017-01-01

Randomized controlled trials (RCTs) and quasi-experimental designs like regression discontinuity (RD) designs, instrumental variable (IV) designs, and matching and propensity score (PS) designs are frequently used for inferring causal effects. It is well known that the features of these designs facilitate the identification of a causal estimand…

Engine With Regression and Neural Network Approximators Designed

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Hopkins, Dale A.

2001-01-01

At the NASA Glenn Research Center, the NASA engine performance program (NEPP, ref. 1) and the design optimization testbed COMETBOARDS (ref. 2) with regression and neural network analysis-approximators have been coupled to obtain a preliminary engine design methodology. The solution to a high-bypass-ratio subsonic waverotor-topped turbofan engine, which is shown in the preceding figure, was obtained by the simulation depicted in the following figure. This engine is made of 16 components mounted on two shafts with 21 flow stations. The engine is designed for a flight envelope with 47 operating points. The design optimization utilized both neural network and regression approximations, along with the cascade strategy (ref. 3). The cascade used three algorithms in sequence: the method of feasible directions, the sequence of unconstrained minimizations technique, and sequential quadratic programming. The normalized optimum thrusts obtained by the three methods are shown in the following figure: the cascade algorithm with regression approximation is represented by a triangle, a circle is shown for the neural network solution, and a solid line indicates original NEPP results. The solutions obtained from both approximate methods lie within one standard deviation of the benchmark solution for each operating point. The simulation improved the maximum thrust by 5 percent. The performance of the linear regression and neural network methods as alternate engine analyzers was found to be satisfactory for the analysis and operation optimization of air-breathing propulsion engines (ref. 4).

Dropout revisited: patient- and therapist-initiated discontinuation of psychotherapy as a function of organizational instability.

PubMed

Werbart, Andrzej; Andersson, Håkan; Sandell, Rolf

2014-01-01

To explore the association between the stability or instability of services' organizational structure and patient- and therapist-initiated discontinuation of therapy in routine mental health. Three groups, comprising altogether 750 cases in routine mental health care in eight different clinics, were included: cases with patient-initiated discontinuation, therapist-initiated discontinuation, and patients remaining in treatment. Multilevel multinomial regression was used to estimate three models: An initial, unconditional intercept-only model, another one including patient variables, and a final model with significant patient and therapist variables including the organizational stability of the therapists' clinic. High between-therapist variability was noted. Odds ratios and significance tests indicated a strong association of organizational instability with patient-initiated premature termination in particular. The question of how organizational factors influence the treatment results needs further research. Future studies have to be designed in ways that permit clinically meaningful subdivision of the patients' and the therapists' decisions for premature termination.

Subsonic Aircraft With Regression and Neural-Network Approximators Designed

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Hopkins, Dale A.

2004-01-01

At the NASA Glenn Research Center, NASA Langley Research Center's Flight Optimization System (FLOPS) and the design optimization testbed COMETBOARDS with regression and neural-network-analysis approximators have been coupled to obtain a preliminary aircraft design methodology. For a subsonic aircraft, the optimal design, that is the airframe-engine combination, is obtained by the simulation. The aircraft is powered by two high-bypass-ratio engines with a nominal thrust of about 35,000 lbf. It is to carry 150 passengers at a cruise speed of Mach 0.8 over a range of 3000 n mi and to operate on a 6000-ft runway. The aircraft design utilized a neural network and a regression-approximations-based analysis tool, along with a multioptimizer cascade algorithm that uses sequential linear programming, sequential quadratic programming, the method of feasible directions, and then sequential quadratic programming again. Optimal aircraft weight versus the number of design iterations is shown. The central processing unit (CPU) time to solution is given. It is shown that the regression-method-based analyzer exhibited a smoother convergence pattern than the FLOPS code. The optimum weight obtained by the approximation technique and the FLOPS code differed by 1.3 percent. Prediction by the approximation technique exhibited no error for the aircraft wing area and turbine entry temperature, whereas it was within 2 percent for most other parameters. Cascade strategy was required by FLOPS as well as the approximators. The regression method had a tendency to hug the data points, whereas the neural network exhibited a propensity to follow a mean path. The performance of the neural network and regression methods was considered adequate. It was at about the same level for small, standard, and large models with redundancy ratios (defined as the number of input-output pairs to the number of unknown coefficients) of 14, 28, and 57, respectively. In an SGI octane workstation (Silicon Graphics

Discontinuation of nicotine replacement therapy among smoking-cessation attempters.

PubMed

Burns, Emily K; Levinson, Arnold H

2008-03-01

Nicotine replacement therapy (NRT) doubles successful quitting, but more than half of NRT users do not comply with optimal treatment regimens. From the 2005 Colorado state tobacco survey, quit attempters who utilized NRT (N=366) were analyzed in spring 2007. Descriptive and regression analyses were used to examine reasons for discontinuing NRT, length of time on NRT, and quit intentions. The reasons for discontinuing NRT were resuming smoking (34%), side effects (17%), NRT not helping with quitting (14%), quitting smoking (10%), and cost (5%). Poverty, age, and non-Latino minority status were associated with reasons for discontinuation other than quitting smoking. Having side effects was associated with a short duration of NRT use and 95% lower odds of intending to quit in the next month. In the first population-level study examining reasons for discontinuing NRT, general-population smokers who initiate NRT use when attempting to quit are highly likely to discontinue NRT prematurely. Age and culturally-appropriate medication management interventions may increase NRT compliance and improve cessation outcomes.

Treatment eligibility and retention in clinical HIV care: A regression discontinuity study in South Africa

PubMed Central

Bor, Jacob; Tanser, Frank; Bärnighausen, Till

2017-01-01

Background Loss to follow-up is high among HIV patients not yet receiving antiretroviral therapy (ART). Clinical trials have demonstrated the clinical efficacy of early ART; however, these trials may miss an important real-world consequence of providing ART at diagnosis: its impact on retention in care. Methods and findings We examined the effect of immediate (versus deferred) ART on retention in care using a regression discontinuity design. The analysis included all patients (N = 11,306) entering clinical HIV care with a first CD4 count between 12 August 2011 and 31 December 2012 in a public-sector HIV care and treatment program in rural South Africa. Patients were assigned to immediate versus deferred ART eligibility, as determined by a CD4 count < 350 cells/μl, per South African national guidelines. Patients referred to pre-ART care were instructed to return every 6 months for CD4 monitoring. Patients initiated on ART were instructed to return at 6 and 12 months post-initiation and annually thereafter for CD4 and viral load monitoring. We assessed retention in HIV care at 12 months, as measured by the presence of a clinic visit, lab test, or ART initiation 6 to 18 months after initial CD4 test. Differences in retention between patients presenting with CD4 counts just above versus just below the 350-cells/μl threshold were estimated using local linear regression models with a data-driven bandwidth and with the algorithm for selecting the bandwidth chosen ex ante. Among patients with CD4 counts close to the 350-cells/μl threshold, having an ART-eligible CD4 count (<350 cells/μl) was associated with higher 12-month retention than not having an ART-eligible CD4 count (50% versus 32%), an intention-to-treat risk difference of 18 percentage points (95% CI 11 to 23; p < 0.001). The decision to start ART was determined by CD4 count for one in four patients (25%) presenting close to the eligibility threshold (95% CI 20% to 31%; p < 0.001). In this subpopulation

Effect of air quality alerts on human health: a regression discontinuity analysis in Toronto, Canada.

PubMed

Chen, Hong; Li, Qiongsi; Kaufman, Jay S; Wang, Jun; Copes, Ray; Su, Yushan; Benmarhnia, Tarik

2018-01-01

Ambient air pollution is a major health risk globally. To reduce adverse health effects on days when air pollution is high, government agencies worldwide have implemented air quality alert programmes. Despite their widespread use, little is known about whether these programmes produce any observable public-health benefits. We assessed the effectiveness of such programmes using a quasi-experimental approach. We assembled a population-based cohort comprising all individuals who resided in the city of Toronto (Ontario, Canada) from 2003 to 2012 (about 2·6 million people). We ascertained seven health outcomes known to be affected by short-term elevation of air pollution, using provincial health administrative databases. These health outcomes were cardiovascular-related mortality, respiratory-related mortality, and hospital admissions or emergency-department visits for acute myocardial infarction, heart failure, stroke, asthma, and chronic obstructive pulmonary disease (COPD). We applied a regression discontinuity design to assess the effectiveness of an intervention (ie, the air quality alert programme). To quantify the effect of the air quality alert programme, we estimated for each outcome both the absolute rate difference and the rate ratio attributable to programme eligibility (by intention-to-treat analysis) and the alerts themselves (by two-stage regression approach), respectively. Between Jan 1, 2003, and Dec 31, 2012, on average between three and 27 daily cardiovascular or respiratory events were reported in Toronto (depending on the outcome). Alert announcements reduced asthma-related emergency-department visits by 4·73 cases per 1 000 000 people per day (95% CI 0·55-9·38), or in relative terms by 25% (95% CI 1-47). Programme eligibility also led to 2·05 (95% CI 0·07-4·00) fewer daily emergency-department visits for asthma. We did not detect a significant reduction in any other health outcome as a result of alert announcements or programme

Safety of discontinuing cotrimoxazole prophylaxis among HIV infected adults on anti-retroviral therapy in Uganda (COSTOP trial): Design.

PubMed

Anywaine, Zacchaeus; Abaasa, Andrew; Levin, Jonathan; Kasirye, Ronnie; Kamali, Anatoli; Grosskurth, Heiner; Munderi, Paula; Nunn, Andrew

2015-07-01

Cotrimoxazole (CTX) prophylaxis is recommended by the World Health Organisation for HIV infected persons. However, once HIV infected patients have commenced ART in resource limited settings, the benefits of continued CTX prophylaxis are not known. The few studies that investigated the safety of discontinuing CTX prophylaxis in these settings had limitations due to their design. COSTOP is a randomised double blind placebo controlled non-inferiority trial among HIV infected Ugandan adults stabilised on anti-retroviral treatment (ART). Participants with CD4 count of 250 or more cells/mm(3) are randomised to two arms: the intervention arm in which CTX is discontinued and the control arm in which CTX prophylaxis is continued. The study aims to assess whether the intervention regimen is not inferior, with respect to the incidence of pre-defined CTX-preventable events, to the control regimen and superior with respect to the incidence of haematological adverse events. Studies that have previously evaluated the safety of discontinuing CTX prophylaxis among HIV infected adults in resource limited settings have provided moderate to low quality evidence owing in part to methodological limitations. COSTOP is designed and conducted with sufficient rigour to answer this question. The results of the trial will assist in guiding policy recommendations. This paper describes the design and methodological considerations important for the conduct of CTX cessation studies. Copyright © 2015. Published by Elsevier Inc.

FEMALE SEX AND DISCONTINUATION OF ISONIAZID DUE TO ADVERSE EFFECTS DURING THE TREATMENT OF LATENT TUBERCULOSIS

PubMed Central

Pettit, April C.; Bethel, James; Hirsch-Moverman, Yael; Colson, Paul W.; Sterling, Timothy R.

2013-01-01

SUMMARY Objectives To determine the rate of and risk factors for discontinuation of isoniazid due to adverse effects during the treatment of latent tuberculosis infection in a large, multi-site study. Methods The Tuberculosis Epidemiologic Studies Consortium (TBESC) conducted a prospective study from March 2007–September 2008 among adults initiating isoniazid for treatment of LTBI at 12 sites in the US and Canada. The relative risk for isoniazid discontinuation due to adverse effects was determined using negative binomial regression. Adjusted models were constructed using forward stepwise regression. Results Of 1,306 persons initiating isoniazid, 617 (47.2%, 95% CI 44.5–50.0%) completed treatment and 196 (15.0%, 95% CI 13.1–17.1%) discontinued due to adverse effects. In multivariable analysis, female sex (RR 1.67, 95% CI 1.32–2.10, p<0.001) and current alcohol use (RR 1.41, 95% CI 1.13–1.77, p=0.003) were independently associated with isoniazid discontinuation due to adverse effects. Conclusions The rate of discontinuation of isoniazid due to adverse effects was substantially higher than reported earlier. Women were at increased risk of discontinuing isoniazid due to adverse effects; close monitoring of women for adverse effects may be warranted. Current alcohol use was also associated with isoniazid discontinuation; counseling patients to abstain from alcohol could decrease discontinuation due to adverse effects. PMID:23845828

Skipping Class in College and Exam Performance: Evidence from a Regression Discontinuity Classroom Experiment

ERIC Educational Resources Information Center

Dobkin, Carlos; Gil, Ricard; Marion, Justin

2010-01-01

In this paper we estimate the effect of class attendance on exam performance by implementing a policy in three large economics classes that required students scoring below the median on the midterm exam to attend class. This policy generated a large discontinuity in the rate of post-midterm attendance at the median of the midterm score. We…

The Role of Cultural Discontinuity in the Academic Outcomes of Latina/o High School Students

ERIC Educational Resources Information Center

Taggart, Amanda

2017-01-01

This study examined the impact of cultural discontinuity on the academic outcomes of Latina/o high school students. Hierarchical multiple regression was utilized to (a) investigate the significant differences between the characteristics and academic outcomes of high school students who do and do not experience cultural discontinuity between their…

39 CFR 241.3 - Discontinuance of post offices.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... These rules are designed to ensure that the reasons leading a district manager, Customer Service and... originally assigned to the discontinued post office may be changed if the responsible district manager... to the discontinued post office. (ii) If the ZIP Code is changed and the parent post office covers...

Application of Three Quasi-Experimental Designs.

ERIC Educational Resources Information Center

Cordray, David S.

Presented as part of a symposium on evaluation on juvenile diversion programs, this brief paper describes several specific research procedures which have been utilized to help decide which type of diversion approach is best for specific types of clients. Procedures discussed are the regression discontinuity design, the tie-breaker design, and the…

Premature trial discontinuation often not accurately reflected in registries: comparison of registry records with publications.

PubMed

Alturki, Reem; Schandelmaier, Stefan; Olu, Kelechi Kalu; von Niederhäusern, Belinda; Agarwal, Arnav; Frei, Roy; Bhatnagar, Neera; Hooft, Lotty; von Elm, Erik; Briel, Matthias

2017-01-01

One quarter of randomized clinical trials (RCTs) are prematurely discontinued and frequently remain unpublished. Trial registries can document whether a trial is ongoing, suspended, discontinued, or completed and therefore represent an important source for trial status information. The accuracy of this information is unclear. To examine the accuracy of completion status and reasons for discontinuation documented in trial registries as compared to corresponding publications of discontinued RCTs and to investigate potential predictors for accurate trial status information in registries. We conducted a cross-sectional study comparing information provided in publications (reference standard) to corresponding registry entries. First, we reviewed publications of RCTs providing information on both discontinuation and registration. We identified eligible publications through systematic searches of MEDLINE and EMBASE (2010-2014) and an international cohort of 1,017 RCTs initiated between 2000 and 2003. Second, pairs of investigators independently and in duplicate extracted data from publications and corresponding registry records. Third, for each discontinued RCT, we compared publication information to registry information. We used multivariable regression to examine whether accurate labeling of trials as discontinued (vs. other status) in the registry was associated with recent initiation of RCT, industry sponsorship, multicenter design, or larger sample size. We identified 173 publications of RCTs that were discontinued due to slow recruitment (55%), harm (16%), futility (11%), benefit (5%), other reasons (3%), or multiple reasons (9%). Trials were registered with clinicaltrials.gov (77%), isrctn.com (14%), or other registries (8%). Of the 173 corresponding registry records, 77 (45%) trials were labeled as discontinued and 57 (33%) provided a reason for discontinuation (of which 53, 93%, provided the same reason as in the publication). Labeling of discontinued trials as

Primary care providers’ perspectives on discontinuing prostate cancer screening

PubMed Central

Pollack, Craig E.; Platz, Elizabeth A.; Bhavsar, Nrupen A.; Noronha, Gary; Green, Gene E.; Chen, Sean; Carter, H. Ballentine

2012-01-01

Background Clinical guidelines recommend against routine prostate specific antigen (PSA) screening in older men and those with lower life expectancies. We examined providers’ decision-making regarding discontinuing PSA screening. Methods We administered a survey of primary providers from a large, university-affiliated primary care practice. Providers were asked about their current screening practices, factors that influence their decision to discontinue screening, and barriers to discontinuing screening. Bivariate and multivariable logistic regression analyses were used to examine whether taking age and/or life expectancy into account and barriers to discontinuing were associated with clinician characteristics and practice styles. Results 88.7% of providers participated in the survey (125 out of 141). Over half (59.3%) took both age and life expectancy into account whereas 12.2% did not consider either in their decisions to discontinue PSA screening. Providers varied with the age they typically stop screening and majority (66.4%) report difficulty in assessing life expectancy. Taking patient age and life expectancy into account was not associated with provider characteristics or practice styles. The most frequently cited barriers to discontinuing PSA screening were patient expectation (74.4%) and time constraints (66.4%). Black providers were significantly less likely than non-black providers to endorse barriers related to time constraints and clinical uncertainty, though these results are limited by the small sample size of black providers. Conclusion Though age and life expectancy often figure prominently in decisions to employ screening, providers face multiple barriers to discontinue PSA routine screening, PMID:22517310

Method for simulating discontinuous physical systems

DOEpatents

Baty, Roy S.; Vaughn, Mark R.

2001-01-01

The mathematical foundations of conventional numerical simulation of physical systems provide no consistent description of the behavior of such systems when subjected to discontinuous physical influences. As a result, the numerical simulation of such problems requires ad hoc encoding of specific experimental results in order to address the behavior of such discontinuous physical systems. In the present invention, these foundations are replaced by a new combination of generalized function theory and nonstandard analysis. The result is a class of new approaches to the numerical simulation of physical systems which allows the accurate and well-behaved simulation of discontinuous and other difficult physical systems, as well as simpler physical systems. Applications of this new class of numerical simulation techniques to process control, robotics, and apparatus design are outlined.

Estimating the real-world effects of expanding antiretroviral treatment eligibility: Evidence from a regression discontinuity analysis in Zambia

PubMed Central

Sikazwe, Izukanji; Wa Mwanza, Mwanza; Savory, Theodora; Sikombe, Kombatende; Somwe, Paul; Roy, Monika; Padian, Nancy

2018-01-01

Background Although randomized trials have established the clinical efficacy of treating all persons living with HIV (PLWHs), expanding treatment eligibility in the real world may have additional behavioral effects (e.g., changes in retention) or lead to unintended consequences (e.g., crowding out sicker patients owing to increased patient volume). Using a regression discontinuity design, we sought to assess the effects of a previous change to Zambia’s HIV treatment guidelines increasing the threshold for treatment eligibility from 350 to 500 cells/μL to anticipate effects of current global efforts to treat all PLWHs. Methods and findings We analyzed antiretroviral therapy (ART)-naïve adults who newly enrolled in HIV care in a network of 64 clinics operated by the Zambian Ministry of Health and supported by the Centre for Infectious Disease Research in Zambia (CIDRZ). Patients were restricted to those enrolling in a narrow window around the April 1, 2014 change to Zambian HIV treatment guidelines that raised the CD4 threshold for treatment from 350 to 500 cells/μL (i.e., August 1, 2013, to November 1, 2014). Clinical and sociodemographic data were obtained from an electronic medical record system used in routine care. We used a regression discontinuity design to estimate the effects of this change in treatment eligibility on ART initiation within 3 months of enrollment, retention in care at 6 months (defined as clinic attendance between 3 and 9 months after enrollment), and a composite of both ART initiation by 3 months and retention in care at 6 months in all new enrollees. We also performed an instrumental variable (IV) analysis to quantify the effect of actually initiating ART because of this guideline change on retention. Overall, 34,857 ART-naïve patients (39.1% male, median age 34 years [IQR 28–41], median CD4 268 cells/μL [IQR 134–430]) newly enrolled in HIV care during this period; 23,036 were analyzed after excluding patients around the

Estimating the real-world effects of expanding antiretroviral treatment eligibility: Evidence from a regression discontinuity analysis in Zambia.

PubMed

Mody, Aaloke; Sikazwe, Izukanji; Czaicki, Nancy L; Wa Mwanza, Mwanza; Savory, Theodora; Sikombe, Kombatende; Beres, Laura K; Somwe, Paul; Roy, Monika; Pry, Jake M; Padian, Nancy; Bolton-Moore, Carolyn; Holmes, Charles B; Geng, Elvin H

2018-06-01

Although randomized trials have established the clinical efficacy of treating all persons living with HIV (PLWHs), expanding treatment eligibility in the real world may have additional behavioral effects (e.g., changes in retention) or lead to unintended consequences (e.g., crowding out sicker patients owing to increased patient volume). Using a regression discontinuity design, we sought to assess the effects of a previous change to Zambia's HIV treatment guidelines increasing the threshold for treatment eligibility from 350 to 500 cells/μL to anticipate effects of current global efforts to treat all PLWHs. We analyzed antiretroviral therapy (ART)-naïve adults who newly enrolled in HIV care in a network of 64 clinics operated by the Zambian Ministry of Health and supported by the Centre for Infectious Disease Research in Zambia (CIDRZ). Patients were restricted to those enrolling in a narrow window around the April 1, 2014 change to Zambian HIV treatment guidelines that raised the CD4 threshold for treatment from 350 to 500 cells/μL (i.e., August 1, 2013, to November 1, 2014). Clinical and sociodemographic data were obtained from an electronic medical record system used in routine care. We used a regression discontinuity design to estimate the effects of this change in treatment eligibility on ART initiation within 3 months of enrollment, retention in care at 6 months (defined as clinic attendance between 3 and 9 months after enrollment), and a composite of both ART initiation by 3 months and retention in care at 6 months in all new enrollees. We also performed an instrumental variable (IV) analysis to quantify the effect of actually initiating ART because of this guideline change on retention. Overall, 34,857 ART-naïve patients (39.1% male, median age 34 years [IQR 28-41], median CD4 268 cells/μL [IQR 134-430]) newly enrolled in HIV care during this period; 23,036 were analyzed after excluding patients around the threshold to allow for clinic

Drug Side Effects and Retention on HIV Treatment: a Regression Discontinuity Study of Tenofovir Implementation in South Africa and Zambia.

PubMed

Brennan, Alana T; Bor, Jacob; Davies, Mary-Ann; Wandeler, Gilles; Prozesky, Hans; Fatti, Geoffrey; Wood, Robin; Stinson, Kathryn; Tanser, Frank; Bärnighausen, Till; Boulle, Andrew; Sikazwe, Izukanji; Zanolini, Arianna; Fox, Matthew P

2018-05-15

Tenofovir is less toxic than other nucleoside reverse transcriptase inhibitors used in antiretroviral therapy (ART) and may improve retention of HIV-infected patients on ART. We assessed the impact of national guideline changes in South Africa (2010) and Zambia (2007) recommending tenofovir in first-line ART. We applied regression discontinuity in a prospective cohort of 52,294 HIV-infected adults initiating first-line ART within ±12-months of each guideline change. We compared outcomes in patients presenting just before/after the guideline changes using local linear regression and estimated intention-to-treat effects on initiation of tenofovir, retention in care, and other treatment outcomes at 24-months. We assessed complier causal effects among patients starting tenofovir. The new guidelines increased the percentage of patients initiating tenofovir in South Africa (risk difference (RD): 81%; 95% confidence interval (CI): 73, 89) and Zambia (RD: 42%; 95% CI: 38, 45). With the guideline change, single-drug substitutions decreased substantially in South Africa (RD: -15%; 95% CI:-18, -12). Starting tenofovir also reduced attrition in Zambia (intent-to-treat RD: -1.8%; 95% CI: -3.5, -0.1, complier relative risk = 0.74) but not in South Africa (RD: -0.9%; 95% CI: -5.9, 4.1, Complier Relative Risk = 0.94). These results highlight the importance of reducing side effects for increasing retention in care, as well as the differences in population impact of policies with heterogeneous treatment effects implemented in different contexts.

Factors associated with discontinuation of aripiprazole treatment after switching from other antipsychotics in patients with chronic schizophrenia: A prospective observational study.

PubMed

Takaesu, Yoshikazu; Kishimoto, Taishiro; Murakoshi, Akiko; Takahashi, Nobutada; Inoue, Yuichi

2016-02-28

The purpose of the study was to identify factors associated with discontinuation of aripiprazole after switching from other antipsychotics in patients with schizophrenia in real world clinical settings. From January 2011 to December 2012, a prospective, 48-week open-label study was undertaken. Thirty-eight subjects on antipsychotic monotherapy were switched to aripiprazole. Patients who discontinued aripiprazole were compared to those who continued with regards to demographic characteristics as well as treatment factors. Multiple regression analysis was conducted to identify predictors for aripiprazole discontinuation. Thirteen out of 38 patients (34.2%) discontinued aripiprazole during the follow up period. Nine patients (23.7%) discontinued aripiprazole due to worsening of psychotic symptoms. Multiple logistic regression analysis revealed that only the duration of previous antipsychotic treatment was associated with aripiprazole discontinuation after switching to aripiprazole. The receiver operating curve (ROC) analysis identified that the cut-off length for duration of illness to predict aripiprazole discontinuation was 10.5 years. Longer duration of illness was associated with aripiprazole discontinuation. Greater caution may be required when treating such patients with aripiprazole. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The effect of Medicaid premiums on enrollment: a regression discontinuity approach.

PubMed

Dague, Laura

2014-09-01

This paper estimates the effect that premiums in Medicaid have on the length of enrollment of program beneficiaries. Whether and how low income-families will participate in the exchanges and in states' Medicaid programs depends crucially on the structure and amounts of the premiums they will face. I take advantage of discontinuities in the structure of Wisconsin's Medicaid program to identify the effects of premiums on enrollment for low-income families. I use a 3-year administrative panel of enrollment data to estimate these effects. I find an increase in the premium from 0 to 10 dollars per month results in 1.4 fewer months enrolled and reduces the probability of remaining enrolled for a full year by 12 percentage points, but other discrete changes in premium amounts do not affect enrollment or have a much smaller effect. I find no evidence of program enrollees intentionally decreasing labor supply in order to avoid the premiums. Copyright © 2014 Elsevier B.V. All rights reserved.

General practitioners' decisions about discontinuation of medication: an explorative study.

PubMed

Nixon, Michael Simon; Vendelø, Morten Thanning

2016-06-20

Purpose - The purpose of this paper is to investigate how general practitioners' (GPs) decisions about discontinuation of medication are influenced by their institutional context. Design/methodology/approach - In total, 24 GPs were interviewed, three practices were observed and documents were collected. The Gioia methodology was used to analyse data, drawing on a theoretical framework that integrate the sensemaking perspective and institutional theory. Findings - Most GPs, who actively consider discontinuation, are reluctant to discontinue medication, because the safest course of action for GPs is to continue prescriptions, rather than discontinue them. The authors conclude that this is in part due to the ambiguity about the appropriateness of discontinuing medication, experienced by the GPs, and in part because the clinical guidelines do not encourage discontinuation of medication, as they offer GPs a weak frame for discontinuation. Three reasons for this are identified: the guidelines provide dominating triggers for prescribing, they provide weak priming for discontinuation as an option, and they underscore a cognitive constraint against discontinuation. Originality/value - The analysis offers new insights about decision making when discontinuing medication. It also offers one of the first examinations of how the institutional context embedding GPs influences their decisions about discontinuation. For policymakers interested in the discontinuation of medication, the findings suggest that de-stigmatising discontinuation on an institutional level may be beneficial, allowing GPs to better justify discontinuation in light of the ambiguity they experience.

Age at treatment predicts reason for discontinuation of TNF antagonists: data from the BIOBADASER 2.0 registry.

PubMed

Busquets, Noemí; Tomero, Eva; Descalzo, Miguel Ángel; Ponce, Andrés; Ortiz-Santamaría, Vera; Surís, Xavier; Carmona, Loreto; Gómez-Reino, Juan J

2011-11-01

To assess the retention rate of TNF antagonists in elderly patients suffering from chronic arthropathies and to identify predictive variables of discontinuation by inefficacy or by adverse events (AEs). All patients treated with TNF antagonists in BIOBADASER 2.0, with a diagnosis of either RA or spondyloarthritis (SpA: AS and PsA) were included and classified as <65 (younger) or ≥65 years of age (older) at start of the treatment. Cumulative incidence function for discontinuation (inefficacy or AE) was estimated as being the alternative reason for a competing risk. Competing-risks regression models were used to measure the association between study groups, covariates and reason for discontinuation. A total of 4851 patients were studied; 2957 RA (2291 in the younger group and 666 in the older group) and 1894 SpA (1795 in the younger group and 99 in the older group). Retention curves were statistically differently stratified by age groups, with the SpA younger group having the largest retention rate. Competing-risks regression models showed that in the older group, AEs were the most common reason for discontinuation regardless of the diagnosis of the patient and TNF antagonist molecule, whereas in the younger group, the most common cause of discontinuation was inefficacy. In conclusion, factors predicting discontinuation of TNF antagonists due to AEs are older age and diagnosis of RA. On the other hand, younger age predicts discontinuation due to lack of efficacy.

Identifying the factors underlying discontinuation of triptans.

PubMed

Wells, Rebecca E; Markowitz, Shira Y; Baron, Eric P; Hentz, Joseph G; Kalidas, Kavita; Mathew, Paul G; Halker, Rashmi; Dodick, David W; Schwedt, Todd J

2014-02-01

To identify factors associated with triptan discontinuation among migraine patients. It is unclear why many migraine patients who are prescribed triptans discontinue this treatment. This study investigated correlates of triptan discontinuation with a focus on potentially modifiable factors to improve compliance. This multicenter cross-sectional survey (n = 276) was performed at US tertiary care headache clinics. Headache fellows who were members of the American Headache Society Headache Fellows Research Consortium recruited episodic and chronic migraine patients who were current triptan users (use within prior 3 months and for ≥1 year) or past triptan users (no use within 6 months; prior use within 2 years). Univariate analyses were first completed to compare current triptan users to past users for: migraine characteristics, other migraine treatments, triptan education, triptan efficacy, triptan side effects, type of prescribing provider, Migraine Disability Assessment (MIDAS) scores and Beck Depression Inventory (BDI) scores. Then, a multivariable logistic regression model was selected from all possible combinations of predictor variables to determine the factors that best correlated with triptan discontinuation. Compared with those still using triptans (n = 207), those who had discontinued use (n = 69) had higher rates of medication overuse (30 vs. 18%, P = .04) and were more likely to have ever used opioids for migraine treatment (57 vs. 38%, P = .006) as well as higher MIDAS (mean 63 vs. 37, P = .001) and BDI scores (mean 10.4 vs. 7.4, P = .009). Compared with discontinued users, current triptan users were more likely to have had their triptan prescribed by a specialist (neurologist, headache specialist, or pain specialist) (74 vs. 54%, P = .002) and were more likely to report headache resolution (53 vs. 14%, P < .001) or a reduction in pain intensity (71 vs. 28%, P < .001) most of the time from their triptan. On a 1

Estimating conditional proportion curves by regression residuals.

PubMed

Han, Bing; Lim, Nelson

2010-06-15

Researchers often derive a categorical outcome from an observed continuous measurement y. For example, human obesity status can be defined by the body mass index. They proceed to estimate the conditional proportion curve p(x) = P(ydiscontinuity or non-smoothness in the conditional proportion curve p(x). We propose a fully nonparametric empirical estimator using the standardized regression residuals from the general location-scale model y=m(x) + v(x)e for the original continuous measurement. We prove the consistency of the proposed estimator in regular settings. The proposed estimator has several attractive features: it readily provides estimates for alternative cutoff values, and easily accommodates the discontinuity in p(x) caused by special cutoff. Numerical examples demonstrate that our method has better performance in mean-squared error than some alternative approaches. We also discuss a design-adjusted version of the proposed estimators to accommodate survey designs. The proposed methods are applied to data on obesity measurements among female Hispanic Americans. This new approach can be applied to other epidemiological and socio-economic research that needs to define population categories from underlying continuous measurements. Copyright (c) 2010 John Wiley & Sons, Ltd.

Fitness in animals correlates with proximity to discontinuities in body mass distributions.

USGS Publications Warehouse

Angeler, David G.; Allen, Craig R.; Vila-Gispert, Anna; Almeida, David

2014-01-01

Discontinuous structure in landscapes may cause discontinuous, aggregated species body-mass patterns, reflecting the scales of structure available to animal communities within a landscape. Empirical analyses have shown that the location of species within body mass aggregations, which reflect this scale-specific organization, is non-random with regard to several ecological phenomena, including species extinctions. The propensity of declining species to have body masses proximate to discontinuities suggests that transition zones between scaling regimes ultimately decreases the ecological fitness for some species. We test this proposition using vulnerable and unthreatened fish species in Mediterranean streams with differing levels of human impact. We show that the proximity to discontinuities in body mass aggregations (“distance-to-edge”) of more vs. less fit individuals within vulnerable and unthreatened populations differs. Specifically, regression analysis between the scaled mass index, a proxy of animal fitness, and distance-to-edge reveals negative and positive relationships for vulnerable and unthreatened species, respectively. That is, fitness is higher close to discontinuities in vulnerable populations and toward the center of body mass aggregation groups in unthreatened populations. Our results demonstrate the suitability of the discontinuity framework for scrutinizing non-random patterns of environmental impact in populations. Further exploration of the usefulness of this method across other ecosystems and organism groups is warranted.

Design of energy-storage reactors for single-winding constant-frequency dc-to-dc converters operating in the discontinuous-reactor-current mode

NASA Technical Reports Server (NTRS)

Chen, D. Y.; Owen, H. A., Jr.; Wilson, T. G.

1980-01-01

This paper presents an algorithm and equations for designing the energy-storage reactor for dc-to-dc converters which are constrained to operate in the discontinuous-reactor-current mode. This design procedure applied to the three widely used single-winding configurations: the voltage step-up, the current step-up, and the voltage-or-current step-up converters. A numerical design example is given to illustrate the use of the design algorithm and design equations.

Risk of Vascular Thrombotic Events Following Discontinuation of Antithrombotics After Peptic Ulcer Bleeding.

PubMed

Kim, Seung Young; Hyun, Jong Jin; Suh, Sang Jun; Jung, Sung Woo; Jung, Young Kul; Koo, Ja Seol; Yim, Hyung Joon; Park, Jong Jae; Chun, Hoon Jai; Lee, Sang Woo

2016-04-01

To evaluate whether the risk of cardiovascular events increases when antithrombotics are discontinued after ulcer bleeding. Peptic ulcer bleeding associated with antithrombotics has increased due to the increase in the proportion of elderly population. Little is known about the long-term effects of discontinuing antithrombotics after peptic ulcer bleeding. The aim of this study was to evaluate whether the risk of cardiovascular events increases when antithrombotics are discontinued after ulcer bleeding. We reviewed the medical records of patients with ulcer bleeding who were taking antiplatelet agents or anticoagulants at the time of ulcer bleeding. Cox-regression model was used to adjust for potential confounders, and analyzed association between discontinuation of antithrombotic drugs after ulcer bleeding and thrombotic events such as ischemic heart disease or stroke. Of the 544 patients with ulcer bleeding, 72 patients who were taking antithrombotics and followed up for >2 months were analyzed. Forty patients discontinued antithrombotics after ulcer bleeding (discontinuation group) and 32 patients continued antithrombotics with or without transient interruption (continuation group). Thrombotic events developed more often in discontinuation group than in the continuation group [7/32 (21.9%) vs. 1/40 (2.5%), P=0.019]. Hazard ratio for thrombotic event when antithrombotics were continuously discontinued was 10.9 (95% confidence interval, 1.3-89.7). There were no significant differences in recurrent bleeding events between the 2 groups. Discontinuation of antithrombotics after peptic ulcer bleeding increases the risk of cardiovascular events. Therefore, caution should be taken when discontinuing antithrombotics after ulcer bleeding.

Controller design for global fixed-time synchronization of delayed neural networks with discontinuous activations.

PubMed

Wang, Leimin; Zeng, Zhigang; Hu, Junhao; Wang, Xiaoping

2017-03-01

This paper addresses the controller design problem for global fixed-time synchronization of delayed neural networks (DNNs) with discontinuous activations. To solve this problem, adaptive control and state feedback control laws are designed. Then based on the two controllers and two lemmas, the error system is proved to be globally asymptotically stable and even fixed-time stable. Moreover, some sufficient and easy checked conditions are derived to guarantee the global synchronization of drive and response systems in fixed time. It is noted that the settling time functional for fixed-time synchronization is independent on initial conditions. Our fixed-time synchronization results contain the finite-time results as the special cases by choosing different values of the two controllers. Finally, theoretical results are supported by numerical simulations. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Subsonic Aircraft Design Optimization With Neural Network and Regression Approximators

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Coroneos, Rula M.; Guptill, James D.; Hopkins, Dale A.; Haller, William J.

2004-01-01

The Flight-Optimization-System (FLOPS) code encountered difficulty in analyzing a subsonic aircraft. The limitation made the design optimization problematic. The deficiencies have been alleviated through use of neural network and regression approximations. The insight gained from using the approximators is discussed in this paper. The FLOPS code is reviewed. Analysis models are developed and validated for each approximator. The regression method appears to hug the data points, while the neural network approximation follows a mean path. For an analysis cycle, the approximate model required milliseconds of central processing unit (CPU) time versus seconds by the FLOPS code. Performance of the approximators was satisfactory for aircraft analysis. A design optimization capability has been created by coupling the derived analyzers to the optimization test bed CometBoards. The approximators were efficient reanalysis tools in the aircraft design optimization. Instability encountered in the FLOPS analyzer was eliminated. The convergence characteristics were improved for the design optimization. The CPU time required to calculate the optimum solution, measured in hours with the FLOPS code was reduced to minutes with the neural network approximation and to seconds with the regression method. Generation of the approximators required the manipulation of a very large quantity of data. Design sensitivity with respect to the bounds of aircraft constraints is easily generated.

Egyptian ever-married women's attitude toward discontinuation of female genital cutting.

PubMed

Afifi, M

2010-01-01

This study aimed to examine Egyptian ever-married women's beliefs and attitude toward the discontinuation of female genital cutting (FGC). We also examined the significant sources of information which the women with positive attitude were exposed to the year prior to the survey. In a national representative community-based sample of 15,573 ever-married Egyptian women, the intention to continue the practice of FGC and other sociodemographical variables were collected from the 2000 Egypt Demographic and Health Survey data. A secondary in-depth analysis was conducted on the data in order to investigate the women's attitude and its associated factors. Only 12.4 percent of the sample intended to discontinue the practice. The logistic regression models showed that women with a positive attitude to discontinue the practice believed that FGC was not an important part of religious traditions, that husbands did not prefer a cut wife, and that FGC reduced sexual desire. The most significant sources of information related to a positive attitude to discontinue the practice were community discussions, the mosques or churches and the newspapers. The aforementioned sources of information are related to the social and religious aspects of women in the Egyptian community. In order to change women's attitude toward the discontinuation of this unhealthy practice, communication rather than passive learning is needed.

Comparing Inference Approaches for RD Designs: A Reexamination of the Effect of Head Start on Child Mortality

ERIC Educational Resources Information Center

Cattaneo, Matias D.; Titiunik, Rocío; Vazquez-Bare, Gonzalo

2017-01-01

The regression discontinuity (RD) design is a popular quasi-experimental design for causal inference and policy evaluation. The most common inference approaches in RD designs employ "flexible" parametric and nonparametric local polynomial methods, which rely on extrapolation and large-sample approximations of conditional expectations…

Contraceptive discontinuation and switching among Ghanaian women: evidence from the Ghana Demographic and Health Survey, 2008.

PubMed

Modey, Emefa J; Aryeetey, Richmond; Adanu, Richard

2014-03-01

This study identifies factors associated with contraceptive discontinuation and switching among Ghanaian women of reproductive age, using data from 1,378 female respondents of the 2008 Ghana Demographic and Health Survey. Logistic regression models were used to determine relationships between key socio-demographic factors and user status. Discontinued use occurred among 56% of ever users and switching among 55% of current users. The IUD was most abandoned (70%) and its use was associated with almost twice the odds of discontinuation (OR = 1.97; 95% CI (1.04, 3.75)). Having a history of terminated pregnancy significantly predicted both discontinuation (OR = 1.36; 95% CI (1.03, 1.79) and switching (OR = 1.78; 95% CI (1.16, 2.73)) and intention to limit births significantly predicted lower discontinuation (OR = 0.71; 95% CI (0.52, 0.96)). Counseling services emphasizing contraceptive options and reinforcing switching are critically needed to reduce unwanted pregnancies that may result from poor method use and discontinuation especially among post-abortion clients and IUD users.

Change in the discontinuation pattern of tumour necrosis factor antagonists in rheumatoid arthritis over 10 years: data from the Spanish registry BIOBADASER 2.0.

PubMed

Gómez-Reino, Juan J; Rodríguez-Lozano, Carlos; Campos-Fernández, Cristina; Montoro, María; Descalzo, Miguel Ángel; Carmona, Loreto

2012-03-01

To investigate in rheumatoid arthritis (RA) the rate and reason of discontinuation of tumour necrosis factor (TNF) antagonists over the past decade. RA patients in BIOBADASER 2.0 were stratified according to the start date of their first TNF antagonist into 2000-3, 2004-6 and 2007-9 interval years. Cumulative incidence function of discontinuation for inefficacy or toxicity was estimated with the alternative reason as competing risk. Competing risks regression models were used to measure the association of study groups with covariates and reasons for discontinuation. Association is expressed as subhazard ratios (SHR). 2907 RA patients were included in the study. Competing risk regression for inefficacy shows larger SHR for patients starting treatment in 2004-6 (SHR 2.57; 95% CI 1.55 to 4.25) and 2007-9 (SHR 3.4; 95% CI 2.08 to 5.55) than for those starting in 2000-3, after adjusting for TNF antagonists, clinical activity and concomitant treatment. Competing risk regression analysis for adverse events revealed no differences across the three time intervals. In RA, the discontinuation rate of TNF antagonists in the first year of treatment is higher more recently than a decade ago, inefficacy being the main reason for the increased rate. The rate of discontinuation for adverse events has remained stable.

Predictors of Discontinuation of Tumor Necrosis Factor Inhibitors in Patients with Rheumatoid Arthritis

PubMed Central

AGARWAL, SANDEEP K.; GLASS, ROBERTA J.; SHADICK, NANCY A.; COBLYN, JONATHAN S.; ANDERSON, RONALD J.; MAHER, NANCY E.; WEINBLATT, MICHAEL E.; SOLOMON, DANIEL H.

2009-01-01

Objective Tumor necrosis factor-α (TNF) inhibitors have transformed management of rheumatoid arthritis (RA); however, many patients discontinue TNF inhibitors. Our goal was to determine the discontinuation rate of TNF inhibitors and identify predictors associated with discontinuation. Methods Enrollees in the Brigham RA Sequential Study (BRASS) formed the eligible cohort. Patients reporting use of a TNF inhibitor with at least 6 months of followup were followed until reporting TNF inhibitor discontinuation or their last study visit if they continued therapy. Potential predictor variables, including demographic and clinical data assessed at baseline and 6 months prior to study endpoint, were identified using a Cox proportional regression. Results Among 961 patients in BRASS, 503 were using a TNF inhibitor with at least 6 months of followup in BRASS (mean length of followup 39 mo, SD 13). Two hundred ten patients (42%) reported discontinuation of TNF inhibitor. Higher physician global scores (hazard ratio 1.27, 95% CI 1.18–1.38) and RA Disease Activity Index scores (HR 1.13, 95% CI 1.05–1.22) 6 months prior to stopping the TNF inhibitor and higher number of TNF inhibitors used previously (HR 1.30, 95% CI 1.03–1.66) were associated with discontinuation of TNF inhibitor. Prior use of synthetic disease modifying antirheumatic drugs (HR 0.50, 95% CI 0.34–0.72) and more years of cumulative methotrexate use (HR 0.24, 95% CI 0.12–0.47) were inversely associated with discontinuation of TNF inhibitor. Conclusion These data demonstrate that a significant number of patients with RA discontinue TNF inhibitors. Several easily characterized clinical variables have a modest predictive association with reduced probability of TNF inhibitor discontinuation. PMID:18634159

How to achieve long-term breast-feeding: factors associated with early discontinuation.

PubMed

Camurdan, Aysu Duyan; Ilhan, Mustafa N; Beyazova, Ufuk; Sahin, Figen; Vatandas, Nilgun; Eminoglu, Sancar

2008-11-01

To evaluate the factors associated with discontinuation of breast-feeding before 12 months in order to make suggestions for achieving long-term breast-feeding. A descriptive cross-sectional study. Gazi University Medical School, Ankara, Turkey. Mothers of 1230 children who discontinued breast-feeding at least 15 d before the last visit were asked to fill out a questionnaire about the discontinuation process. Logistic regression analysis was performed to assess the independent effects of factors that might influence breast-feeding discontinuation. Mean breast-feeding duration of the study group was 11.04 (SD 7.45) months. Introduction of bottle-feeding correlated with discontinuation of breast-feeding (r=0.507, P = 0.001). Important risk factors for discontinuation of breast-feeding before the first 12 months were not exclusively breast-feeding at 3 and 6 months, prematurity, not having a plan about breast-feeding duration and maternity leave duration of discontinuation were the baby's unwillingness to eat solid foods while breast-feeding and the mother's perception that 'the baby is old enough', respectively. The factors that improve long-term breast-feeding are successful exclusive breast-feeding in the first few months, intention of the mother to breast-feed and sufficient duration of maternity leave. This study emphasizes the importance of successful breast-feeding counselling during the first few months to achieve the desired long-term breast-feeding.

New exponential synchronization criteria for time-varying delayed neural networks with discontinuous activations.

PubMed

Cai, Zuowei; Huang, Lihong; Zhang, Lingling

2015-05-01

This paper investigates the problem of exponential synchronization of time-varying delayed neural networks with discontinuous neuron activations. Under the extended Filippov differential inclusion framework, by designing discontinuous state-feedback controller and using some analytic techniques, new testable algebraic criteria are obtained to realize two different kinds of global exponential synchronization of the drive-response system. Moreover, we give the estimated rate of exponential synchronization which depends on the delays and system parameters. The obtained results extend some previous works on synchronization of delayed neural networks not only with continuous activations but also with discontinuous activations. Finally, numerical examples are provided to show the correctness of our analysis via computer simulations. Our method and theoretical results have a leading significance in the design of synchronized neural network circuits involving discontinuous factors and time-varying delays. Copyright © 2015 Elsevier Ltd. All rights reserved.

Regression Model for Light Weight and Crashworthiness Enhancement Design of Automotive Parts in Frontal CAR Crash

NASA Astrophysics Data System (ADS)

Bae, Gihyun; Huh, Hoon; Park, Sungho

This paper deals with a regression model for light weight and crashworthiness enhancement design of automotive parts in frontal car crash. The ULSAB-AVC model is employed for the crash analysis and effective parts are selected based on the amount of energy absorption during the crash behavior. Finite element analyses are carried out for designated design cases in order to investigate the crashworthiness and weight according to the material and thickness of main energy absorption parts. Based on simulations results, a regression analysis is performed to construct a regression model utilized for light weight and crashworthiness enhancement design of automotive parts. An example for weight reduction of main energy absorption parts demonstrates the validity of a regression model constructed.

Mammographic density changes following discontinuation of tamoxifen in premenopausal women with oestrogen receptor-positive breast cancer.

PubMed

Kim, Won Hwa; Cho, Nariya; Kim, Young-Seon; Yi, Ann

2018-04-06

To evaluate the changes in mammographic density after tamoxifen discontinuation in premenopausal women with oestrogen receptor-positive breast cancers and the underlying factors METHODS: A total of 213 consecutive premenopausal women with breast cancer who received tamoxifen treatment after curative surgery and underwent three mammograms (baseline, after tamoxifen treatment, after tamoxifen discontinuation) were included. Changes in mammographic density after tamoxifen discontinuation were assessed qualitatively (decrease, no change, or increase) by two readers and measured quantitatively by semi-automated software. The association between % density change and clinicopathological factors was evaluated using univariate and multivariate regression analyses. After tamoxifen discontinuation, a mammographic density increase was observed in 31.9% (68/213, reader 1) to 22.1% (47/213, reader 2) by qualitative assessment, with a mean density increase of 1.8% by quantitative assessment compared to density before tamoxifen discontinuation. In multivariate analysis, younger age (≤ 39 years) and greater % density decline after tamoxifen treatment (≥ 17.0%) were independent factors associated with density change after tamoxifen discontinuation (p < .001 and p = .003, respectively). Tamoxifen discontinuation was associated with mammographic density change with a mean density increase of 1.8%, which was associated with younger age and greater density change after tamoxifen treatment. • Increased mammographic density after tamoxifen discontinuation can occur in premenopausal women. • Mean density increase after tamoxifen discontinuation was 1.8%. • Density increase is associated with age and density decrease after tamoxifen.

Exploration of the recurrence in radiation brain necrosis after bevacizumab discontinuation

PubMed Central

Zhuang, Hongqing; Yuan, Xiangkun; Chang, Joe Y.; Song, Yongchun; Wang, Junjie; Yuan, Zhiyong; Wang, Xiaoguang; Wang, Ping

2016-01-01

Objective: The aim of the paper was to investigate the recurrence and its causes of radiation brain necrosis following bevacizumab discontinuation. Methods: This study included 14 patients with radiation brain necrosis (confirmed through imaging) after stereotactic radiotherapy for a primary or metastatic brain tumor and who received bevacizumab treatment from June 2011 through December 2014. The patients received bevacizumab at 5 mg/kg, q3-4w, for at least 3 cycles. The T1 signal intensity from enhanced MRI images was used as the evaluation criteria for the brain necrosis treatment efficacy. Results: brain necrosis improved in 13 of the 14 cases (92.9%). However, during follow-up, 10 of the 13 responsive patients (76.9%) exhibited a recurrence in brain necrosis, and a multiple linear regression analysis shows that brain necrosis recurrence was related to the follow-up time after the initial bevacizumab treatment discontinuation. Conclusion: bevacizumab produced good short-term effects for radiation brain necrosis; however, most of the patients would recurrence after bevacizumab is discontinued. Thus, brain necrosis was irreversible. PMID:26934327

Exploration of the recurrence in radiation brain necrosis after bevacizumab discontinuation.

PubMed

Zhuang, Hongqing; Yuan, Xiangkun; Chang, Joe Y; Song, Yongchun; Wang, Junjie; Yuan, Zhiyong; Wang, Xiaoguang; Wang, Ping

2016-07-26

The aim of the paper was to investigate the recurrence and its causes of radiation brain necrosis following bevacizumab discontinuation. This study included 14 patients with radiation brain necrosis (confirmed through imaging) after stereotactic radiotherapy for a primary or metastatic brain tumor and who received bevacizumab treatment from June 2011 through December 2014. The patients received bevacizumab at 5 mg/kg, q3-4w, for at least 3 cycles. The T1 signal intensity from enhanced MRI images was used as the evaluation criteria for the brain necrosis treatment efficacy. brain necrosis improved in 13 of the 14 cases (92.9%). However, during follow-up, 10 of the 13 responsive patients (76.9%) exhibited a recurrence in brain necrosis, and a multiple linear regression analysis shows that brain necrosis recurrence was related to the follow-up time after the initial bevacizumab treatment discontinuation. bevacizumab produced good short-term effects for radiation brain necrosis; however, most of the patients would recurrence after bevacizumab is discontinued. Thus, brain necrosis was irreversible.

Predictors of premature discontinuation of outpatient treatment after discharge of patients with posttraumatic stress disorder.

PubMed

Wang, Hee Ryung; Woo, Young Sup; Jun, Tae-Youn; Bahk, Won-Myong

2015-01-01

This study aimed to examine the sociodemographic and disease-related variables associated with the premature discontinuation of psychiatric outpatient treatment after discharge among patients with noncombat-related posttraumatic stress disorder. We retrospectively reviewed the medical records of patients who were discharged with a diagnosis of posttraumatic stress disorder. Fifty-five percent of subjects (57/104) prematurely discontinued outpatient treatment within 6 months of discharge. Comparing sociodemographic variables between the 6-month non-follow-up group and 6-month follow-up group, there were no variables that differed between the two groups. However, comparing disease-related variables, the 6-month follow-up group showed a longer hospitalization duration and higher Global Assessment of Function score at discharge. The logistic regression analysis showed that a shorter duration of hospitalization predicted premature discontinuation of outpatient treatment within 6 months of discharge. The duration of psychiatric hospitalization for posttraumatic stress disorder appeared to influence the premature discontinuation of outpatient treatment after discharge.

Efficient logistic regression designs under an imperfect population identifier.

PubMed

Albert, Paul S; Liu, Aiyi; Nansel, Tonja

2014-03-01

Motivated by actual study designs, this article considers efficient logistic regression designs where the population is identified with a binary test that is subject to diagnostic error. We consider the case where the imperfect test is obtained on all participants, while the gold standard test is measured on a small chosen subsample. Under maximum-likelihood estimation, we evaluate the optimal design in terms of sample selection as well as verification. We show that there may be substantial efficiency gains by choosing a small percentage of individuals who test negative on the imperfect test for inclusion in the sample (e.g., verifying 90% test-positive cases). We also show that a two-stage design may be a good practical alternative to a fixed design in some situations. Under optimal and nearly optimal designs, we compare maximum-likelihood and semi-parametric efficient estimators under correct and misspecified models with simulations. The methodology is illustrated with an analysis from a diabetes behavioral intervention trial. © 2013, The International Biometric Society.

Application of Experimental and Quasi-Experimental Research Designs to Educational Software Evaluation.

ERIC Educational Resources Information Center

Muller, Eugene W.

1985-01-01

Develops generalizations for empirical evaluation of software based upon suitability of several research designs--pretest posttest control group, single-group pretest posttest, nonequivalent control group, time series, and regression discontinuity--to type of software being evaluated, and on circumstances under which evaluation is conducted. (MBR)

Changes Ii Pain Intensity Following Discontinuation of Long-Term Opioid Therapy for Chronic Non-Cancer Pain.

PubMed

McPherson, Sterling; Smith, Crystal Lederhos; Dobscha, Steven K; Morasco, Benjamin J; Demidenko, Michael I; Meath, Thomas H A; Lovejoy, Travis I

2018-06-13

Little is known about changes in pain intensity that may occur following discontinuation of long-term opioid therapy (LTOT). The objective of this study was to characterize pain intensity following opioid discontinuation over 12 months. This retrospective VA administrative data study identified N=551 patients nationally who discontinued LTOT. Data over 24 months (12 months prior to and following discontinuation) were abstracted from VA administrative records. Random effects regression analyses examined changes in 0-10 pain numeric rating scale scores over time, while growth mixture models delineated pain trajectory sub-groups. Mean estimated pain at the time of opioid discontinuation was 4.9. Changes in pain following discontinuation were characterized by slight but statistically non-significant declines in pain intensity over 12 months post-discontinuation (B=-0.20, p=0.14). Follow-up growth mixture models identified four pain trajectory classes characterized by the following post-discontinuation pain levels: no pain (average pain at discontinuation=0.37), mild clinically-significant pain (average pain=3.90), moderate clinically-significant pain (average pain=6.33), and severe clinically-significant pain (average pain=8.23). Similar to the overall sample, pain trajectories in each of the four classes were characterized by slight reductions in pain over time, with patients in the mild and moderate pain trajectory categories experiencing the greatest pain reductions post-discontinuation (B=-0.11, p=0.05 and B=-0.11, p=0.04, respectively). Pain intensity following discontinuation of LTOT does not, on average, worsen for patients and may slightly improve, particularly for patients with mild-to-moderate pain at the time of discontinuation. Clinicians should consider these findings when discussing risks of opioid therapy and potential benefits of opioid taper with patients.

Reasons and predictors of discontinuation of running after a running program for novice runners.

PubMed

Fokkema, Tryntsje; Hartgens, Fred; Kluitenberg, Bas; Verhagen, Evert; Backx, Frank J G; van der Worp, Henk; Bierma-Zeinstra, Sita M A; Koes, Bart W; van Middelkoop, Marienke

2018-06-18

To determine the proportion of participants of a running program for novice runners that discontinued running and investigate the main reasons to discontinue and characteristics associated with discontinuation. Prospective cohort study. The study included 774 participants of Start to Run, a 6-week running program for novice runners. Before the start of the program, participants filled-in a baseline questionnaire to collect information on demographics, physical activity and perceived health. The 26-weeks follow-up questionnaire was used to obtain information on the continuation of running (yes/no) and main reasons for discontinuation. To determine predictors for discontinuation of running, multivariable logistic regression was performed. Within 26 weeks after the start of the 6-week running program, 29.5% of the novice runners (n=225) had stopped running. The main reason for discontinuation was a running-related injury (n=108, 48%). Being female (OR 1.74; 95% CI 1.13-2.68), being unsure about the continuation of running after the program (OR 2.06; 95% CI 1.31-3.24) and (almost) no alcohol use (OR 1.62; 95%CI 1.11-2.37) were associated with a higher chance of discontinuation of running. Previous running experience less than one year previously (OR 0.46; 95% CI 0.26-0.83) and a higher score on the RAND-36 subscale physical functioning (OR 0.98; 95% CI 0.96-0.99) were associated with a lower chance of discontinuation. In this group of novice runners, almost one-third stopped running within six months. A running-related injury was the main reason to stop running. Women with a low perceived physical functioning and without running experience were prone to discontinue running. Copyright © 2018. Published by Elsevier Ltd.

Predictors of early discontinuation of basal insulin therapy in type 2 diabetes in primary care.

PubMed

Kostev, K; Dippel, F W; Rathmann, W

2016-04-01

To identify patient-related characteristics and other impact factors predicting early discontinuation of basal insulin therapy in type 2 diabetes in primary care. A total of 4837 patients who started basal insulin therapy (glargine: n=3175; NPH: n=1662) in 1072 general and internal medicine practices throughout Germany were retrospectively analyzed (Disease Analyser Database: 01/2008-03/2014). Early discontinuation was defined as switching back to oral antidiabetic drugs (OAD) therapy within 90 days after first basal insulin prescription (index date, ID). Patient records were assessed 365 days prior and post ID. Logistic regression models were used to adjust for age, sex, diabetes duration, diabetologist care, disease management program participation, HbA1c, and comorbidity. Within 3 months after ID, 202 (6.8%) of glargine patients switched back to OAD (NPH: 130 (8.5%); p<0.05). In multivariable logistic regression, predictors of early basal insulin discontinuation were ≥1 documented hypoglycemia before ID (adjusted Odds ratio; 95% CI: 2.20; 1.27-3.82), diagnosed depression (1.31; 1.01-1.70) and referrals to specialists within 90 days after ID (2.06; 1.61-2.63). Diabetologist care (0.57; 0.36-0.89) and glargine treatment (vs. NPH: 0.78; 0.61-0.98) were related to a lower odds of having early insulin discontinuation. Less than 10% of type 2 diabetes patients switched back to oral antidiabetic drugs within 90 days after start of basal insulin therapy. In particular, patients with baseline depression and frequent or severe hypoglycemia have a higher likelihood for early discontinuation of basal insulin, whereas use of insulin glargine and diabetologist care are related to an increased chance of continuous insulin treatment. Copyright © 2015 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.

Randomized Controlled Studies and Alternative Designs in Outcome Studies: Challenges and Opportunities

ERIC Educational Resources Information Center

Shadish, William R.

2011-01-01

This article reviews several decades of the author's meta-analytic and experimental research on the conditions under which nonrandomized experiments can approximate the results from randomized experiments (REs). Several studies make clear that we can expect accurate effect estimates from the regression discontinuity design, though its statistical…

Risk factors for early treatment discontinuation in patients with obsessive-compulsive disorder

PubMed Central

Diniz, Juliana Belo; Malavazzi, Dante Marino; Fossaluza, Victor; Belotto-Silva, Cristina; Borcato, Sonia; Pimentel, Izabel; Miguel, Euripedes Constantino; Shavitt, Roseli Gedanke

2011-01-01

INTRODUCTION: In obsessive-compulsive disorder, early treatment discontinuation can hamper the effectiveness of first-line treatments. OBJECTIVE: This study aimed to investigate the clinical correlates of early treatment discontinuation among obsessive-compulsive disorder patients. METHODS: A group of patients who stopped taking selective serotonin reuptake inhibitors (SSRIs) or stopped participating in cognitive behavioral therapy before completion of the first twelve weeks (total n = 41; n = 16 for cognitive behavioral therapy and n = 25 for SSRIs) were compared with a paired sample of compliant patients (n = 41). Demographic and clinical characteristics were obtained at baseline using structured clinical interviews. Chi-square and Mann-Whitney tests were used when indicated. Variables presenting a p value <0.15 for the difference between groups were selected for inclusion in a logistic regression analysis that used an interaction model with treatment dropout as the response variable. RESULTS: Agoraphobia was only present in one (2.4%) patient who completed the twelve-week therapy, whereas it was present in six (15.0%) patients who dropped out (p = 0.044). Social phobia was present in eight (19.5%) patients who completed the twelve-week therapy and eighteen (45%) patients who dropped out (p = 0.014). Generalized anxiety disorder was present in eight (19.5%) patients who completed the twelve-week therapy and twenty (50%) dropouts (p = 0.004), and somatization disorder was not present in any of the patients who completed the twelve-week therapy; however, it was present in six (15%) dropouts (p = 0.010). According to the logistic regression model, treatment modality (p = 0.05), agoraphobia, the Brown Assessment of Beliefs Scale scores (p = 0.03) and the Beck Anxiety Inventory (p = 0.02) scores were significantly associated with the probability of treatment discontinuation irrespective of interactions with other variables

Tuberculosis treatment discontinuation and symptom persistence: an observational study of Bihar, India’s public care system covering >100,000,000 inhabitants

PubMed Central

2014-01-01

Background The effectiveness of India’s TB control programs depend critically on patients completing appropriate treatment. Discontinuing treatment prior to completion can leave patients infectious and symptomatic. Developing strategies to reduce early discontinuation requires characterizing its patterns and their link to symptom persistence. Methods The 2011 BEST-TB survey (360 clusters, 11 districts) sampled patients (n = 1007) from Bihar’s public healthcare system who had initiated treatment >6 months prior to being interviewed, administering questionnaires to patients about TB treatment duration and symptoms, prior treatment, and sociodemographic characteristics. Multivariate logistic regression models estimated the risk of treatment discontinuation for these characteristics. Similar models estimated probabilities of symptom persistence to 25 weeks post-treatment initiation adjusting for the same predictors and treatment duration. All models included district fixed effects, robust standard errors, and adjustments for the survey sampling design. Treatment default timing and symptom persistence relied solely on self-report. Results 24% of patients discontinued treatment prior to 25 weeks. Higher likelihood of discontinuation occurred in those who had failed to complete previous TB treatment episodes (aOR: 4.77 [95% CI: 1.98 – 11.53]) and those seeing multiple providers (3.67 per provider [1.94 – 6.95]). Symptoms persisted in 42% of patients discontinuing treatment within 5 weeks versus 28% for completing 25 weeks of treatment. Symptom persistence was more likely for those with prior TB treatment (aOR: 5.05 [1.90 – 13.38]); poorer patients (2.94 [1.51 – 5.72]); and women (1.79 [1.07 – 2.99]). Predictors for treatment discontinuation prior to 16 weeks were similar. Conclusions Premature TB treatment discontinuation and symptom persistence is particularly high among individuals who have failed to complete treatment for a prior episode

Discontinuation and non-publication of randomised clinical trials supported by the main public funding body in Switzerland: a retrospective cohort study.

PubMed

Amstutz, Alain; Schandelmaier, Stefan; Frei, Roy; Surina, Jakub; Agarwal, Arnav; Olu, Kelechi Kalu; Alturki, Reem; Von Niederhäusern, Belinda; Von Elm, Erik; Briel, Matthias

2017-08-01

The Swiss National Science Foundation (SNSF) promotes academic excellence through competitive selection of study proposals and rigorous evaluation of feasibility, but completion status and publication history of SNSF-supported randomised clinical trials (RCTs) remain unclear. The main objectives were to review all healthcare RCTs supported by the SNSF for trial discontinuation and non-publication, to investigate potential risk factors for trial discontinuation due to poor recruitment and non-publication, and to compare findings to other Swiss RCTs not supported by the SNSF. We established a retrospective cohort of all SNSF-supported RCTs for which recruitment and funding had ended in 2015 or earlier. For each RCT, two investigators independently searched corresponding publications in electronic databases. In addition, we approached all principal investigators to ask for additional publications and information about trial discontinuation. Teams of two investigators independently extracted details about study design, recruitment of participants, outcomes, analysis and sample size from the original proposal and, if available, from trial registries and publications. We used multivariable regression analysis to explore potential risk factors associated with discontinuation due to poor recruitment and with non-publication, and to compare our results with data from a previous cohort of Swiss RCTs not supported by the SNSF. We included 101 RCTs supported by the SNSF between 1986 and 2015. Eighty-seven (86%) principal investigators responded to our survey. Overall, 69 (68%) RCTs were completed, 26 (26%) RCTs were prematurely discontinued (all due to slow recruitment) and the completion status remained unclear for 6 (6%) RCTs. For analysing publication status, we excluded 4 RCTs for which follow-up was still ongoing and 9 for which manuscripts were still in preparation. Of the remaining 88 RCTs, 53 (60%) were published as full articles in peer-reviewed journals

Design Sensitivity for a Subsonic Aircraft Predicted by Neural Network and Regression Models

NASA Technical Reports Server (NTRS)

Hopkins, Dale A.; Patnaik, Surya N.

2005-01-01

A preliminary methodology was obtained for the design optimization of a subsonic aircraft by coupling NASA Langley Research Center s Flight Optimization System (FLOPS) with NASA Glenn Research Center s design optimization testbed (COMETBOARDS with regression and neural network analysis approximators). The aircraft modeled can carry 200 passengers at a cruise speed of Mach 0.85 over a range of 2500 n mi and can operate on standard 6000-ft takeoff and landing runways. The design simulation was extended to evaluate the optimal airframe and engine parameters for the subsonic aircraft to operate on nonstandard runways. Regression and neural network approximators were used to examine aircraft operation on runways ranging in length from 4500 to 7500 ft.

Periodic synchronization control of discontinuous delayed networks by using extended Filippov-framework.

PubMed

Cai, Zuowei; Huang, Lihong; Guo, Zhenyuan; Zhang, Lingling; Wan, Xuting

2015-08-01

This paper is concerned with the periodic synchronization problem for a general class of delayed neural networks (DNNs) with discontinuous neuron activation. One of the purposes is to analyze the problem of periodic orbits. To do so, we introduce new tools including inequality techniques and Kakutani's fixed point theorem of set-valued maps to derive the existence of periodic solution. Another purpose is to design a switching state-feedback control for realizing global exponential synchronization of the drive-response network system with periodic coefficients. Unlike the previous works on periodic synchronization of neural network, both the neuron activations and controllers in this paper are allowed to be discontinuous. Moreover, owing to the occurrence of delays in neuron signal, the neural network model is described by the functional differential equation. So we introduce extended Filippov-framework to deal with the basic issues of solutions for discontinuous DNNs. Finally, two examples and simulation experiments are given to illustrate the proposed method and main results which have an important instructional significance in the design of periodic synchronized DNNs circuits involving discontinuous or switching factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reasons and predictive factors for discontinuation of PDE-5 inhibitors despite successful intercourse in erectile dysfunction patients

PubMed Central

Kim, S-C; Lee, Y-S; Seo, K-K; Jung, G-W; Kim, T-H

2014-01-01

This study was aimed to identify characteristics of ED patients who discontinued PDE5i despite successful intercourse. Data were collected using a questionnaire from 34 urologic clinics regardless of the effect (success or failure) of PDE5i treatment by visiting the clinics (717), e-mail (64) or post (101) for 882 ED patients who had previously taken any kind of PDE5i on demand four or more times. Discontinuation of PDE5i was defined if the patient had never taken PDE5i for the previous 1 year despite successful intercourse. Of the 882 patients, 485 were included in the final analysis. Difference in the socio-demographic, ED- and partner-related data between the continuation and discontinuation group and factors influencing discontinuation of the PDE5i were analyzed. Among 485 respondents (mean age, 53.6), 116 (23.9%) had discontinued PDE5i use despite successful intercourse. Most common reasons for the discontinuation were ‘reluctant medication-dependent intercourse' (31.0%), ‘spontaneous recovery of erectile function without further treatment' (30.2%), and ‘high cost' (26.7%). In multiple logistic regression analysis, independent factors influencing discontinuation of the drug were cause of ED (psychogenic), short duration of ED, low education (⩽ middle school), and religion (Catholic). In partner-related compliance, only partner's religion (Catholic) was a significant factor. PMID:24305610

Impact of Discontinuing Contact Precautions for Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus: An Interrupted Time Series Analysis.

PubMed

Bearman, Gonzalo; Abbas, Salma; Masroor, Nadia; Sanogo, Kakotan; Vanhoozer, Ginger; Cooper, Kaila; Doll, Michelle; Stevens, Michael P; Edmond, Michael B

2018-06-01

OBJECTIVETo investigate the impact of discontinuing contact precautions among patients infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) on rates of healthcare-associated infection (HAI). Single-center, quasi-experimental study conducted between 2011 and 2016.METHODSWe employed an interrupted time series design to evaluate the impact of 7 horizontal infection prevention interventions across intensive care units (ICUs) and hospital wards at an 865-bed urban, academic medical center. These interventions included (1) implementation of a urinary catheter bundle in January 2011, (2) chlorhexidine gluconate (CHG) perineal care outside ICUs in June 2011, (3) hospital-wide CHG bathing outside of ICUs in March 2012, (4) discontinuation of contact precautions in April 2013 for MRSA and VRE, (5) assessments and feedback with bare below the elbows (BBE) and contact precautions in August 2014, (6) implementation of an ultraviolet-C disinfection robot in March 2015, and (7) 72-hour automatic urinary catheter discontinuation orders in March 2016. Segmented regression modeling was performed to assess the changes in the infection rates attributable to the interventions.RESULTSThe rate of HAI declined throughout the study period. Infection rates for MRSA and VRE decreased by 1.31 (P=.76) and 6.25 (P=.21) per 100,000 patient days, respectively, and the infection rate decreased by 2.44 per 10,000 patient days (P=.23) for device-associated HAI following discontinuation of contact precautions.CONCLUSIONThe discontinuation of contact precautions for patients infected or colonized with MRSA or VRE, when combined with horizontal infection prevention measures was not associated with an increased incidence of MRSA and VRE device-associated infections. This approach may represent a safe and cost-effective strategy for managing these patients.Infect Control Hosp Epidemiol 2018;39:676-682.

Discontinuous Skeletal Gradient Discretisation methods on polytopal meshes

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

Di Pietro, Daniele A.; Droniou, Jérôme; Manzini, Gianmarco

Here, in this work we develop arbitrary-order Discontinuous Skeletal Gradient Discretisations (DSGD) on general polytopal meshes. Discontinuous Skeletal refers to the fact that the globally coupled unknowns are broken polynomials on the mesh skeleton. The key ingredient is a high-order gradient reconstruction composed of two terms: (i) a consistent contribution obtained mimicking an integration by parts formula inside each element and (ii) a stabilising term for which sufficient design conditions are provided. An example of stabilisation that satisfies the design conditions is proposed based on a local lifting of high-order residuals on a Raviart–Thomas–Nédélec subspace. We prove that the novelmore » DSGDs satisfy coercivity, consistency, limit-conformity, and compactness requirements that ensure convergence for a variety of elliptic and parabolic problems. Lastly, links with Hybrid High-Order, non-conforming Mimetic Finite Difference and non-conforming Virtual Element methods are also studied. Numerical examples complete the exposition.« less

Discontinuous Skeletal Gradient Discretisation methods on polytopal meshes

DOE PAGES

Di Pietro, Daniele A.; Droniou, Jérôme; Manzini, Gianmarco

2017-11-21

Here, in this work we develop arbitrary-order Discontinuous Skeletal Gradient Discretisations (DSGD) on general polytopal meshes. Discontinuous Skeletal refers to the fact that the globally coupled unknowns are broken polynomials on the mesh skeleton. The key ingredient is a high-order gradient reconstruction composed of two terms: (i) a consistent contribution obtained mimicking an integration by parts formula inside each element and (ii) a stabilising term for which sufficient design conditions are provided. An example of stabilisation that satisfies the design conditions is proposed based on a local lifting of high-order residuals on a Raviart–Thomas–Nédélec subspace. We prove that the novelmore » DSGDs satisfy coercivity, consistency, limit-conformity, and compactness requirements that ensure convergence for a variety of elliptic and parabolic problems. Lastly, links with Hybrid High-Order, non-conforming Mimetic Finite Difference and non-conforming Virtual Element methods are also studied. Numerical examples complete the exposition.« less

Impact of hypoglycemic events and HbA1c level on sulfonylurea discontinuation and down-titration.

PubMed

Laires, Pedro A; Tang, Jackson; Fan, Chun Po Steve; Li, Zhiyi; Qiu, Ying; Iglay, Kristy

2017-04-01

A retrospective cohort study using GE Centricity electronic medical records assessed the association between post-index hypoglycemia and HbA1c with discontinuation and down-titration of sulfonylureas among patients with Type 2 diabetes mellitus. Adult patients with an index prescription for a sulfonylurea and ≥12 months' continuous records pre- and post-index were eligible. Sulfonylurea discontinuation and down-titration was assessed 1-year post-index. Discontinuation occurred if the date of a prescription was >90 days from the preceding prescription plus days of supply. Down-titration occurred when a subsequent prescription was lower than the index dose. Cox regression assessed the association between post-index hypoglycemia and HbA1c with time to sulfonylurea discontinuation and down-titration, as well as other factors. 28,371 participants were included in the study; 13,459 (47.4%) were discontinuers, 717 (2.5%) were down-titraters, and 14,195 (50.0%) were continuers. 0.6% of continuers experienced hypoglycemia 1-year post-index, compared with 3.1% of down-titraters and 0.8% of discontinuers (p < 0.0001). Patients with post-index hypoglycemia had a significantly higher rate of discontinuation (hazard ratio [HR] = 1.82, 95% CI: 1.47-2.23) and down-titration (HR = 4.25, 95% CI: 1.92-8.03). Patients with higher post-index HbA1c and use of 2 nd generation sulfonylureas had an increased rate of discontinuation (HR = 1.05, 95% CI: 1.04-1.06; HR = 1.19, 95% CI: 1.14-1.24, respectively). Approximately half of participants who initiated sulfonylureas discontinued or down-titrated therapy within one year. Both post-index hypoglycemia and higher HbA1c were significant risk factors for sulfonylurea treatment change.

Decreased responsiveness following lithium discontinuation in bipolar disorder: A naturalistic observation study.

PubMed

Cakir, Sibel; Yazıcı, Olcay; Post, Robert M

2017-01-01

Lithium is a cornerstone in treatment of bipolar disorder. Findings are conflicting as to whether acquired unresponsiveness occurs following the discontinuation. Retrospective life chart data were evaluated to investigate the incidence of loss of response. Sixty-five patients chosen from a larger cohort, followed with prospective life charts, who discontinued lithium and had a second lithium treatment. Patients who had at least 2 mood episodes when they were drug naïve to describe the natural frequency of illness and 3 mood episodes before the discontinuation were included. The type of response was defined as excellent, partial, or poor according to mirror design method. Eighteen of 65 patients (27.6%) had a decreased response to lithium following its discontinuation. Nine of these patients (13.8%) were unresponsive and nine patients (13.8%) had attenuated response to second lithium treatment. The mean time of discontinuation was longer in the patients who show decreased response (245.8+268.2 vs. 117.9+149.8 days, p=.01). Those who had episode recurrences during the discontinuation were more likely to show reduced responsiveness upon re-treatment. After discontinuation of lithium treatment, more than a quarter of the patients showed an attenuated response or unresponsiveness, and initial partial responders more likely to show unresponsiveness than excellent responders. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

27 CFR 17.187 - Discontinuance of business.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Discontinuance of business... PRODUCTS Miscellaneous Provisions § 17.187 Discontinuance of business. The manufacturer shall notify TTB when business is to be discontinued. Upon discontinuance of business, a manufacturer's entire stock of...

Unplanned medication discontinuation as a potential pharmacovigilance signal: a nested young person cohort study

PubMed Central

2014-01-01

Background Because of relatively small treatment numbers together with low adverse drug reaction (ADR) reporting rates the timely identification of ADRs affecting children and young people is problematic. The primary objective of this study was to assess the utility of unplanned medication discontinuation as a signal for possible ADRs in children and young people. Methods Using orlistat as an exemplar, all orlistat prescriptions issued to patients up to 18 years of age together with patient characteristics, prescription duration, co-prescribed medicines and recorded clinical (Read) codes were identified from the Primary Care Informatics Unit database between 1st Jan 2006-30th Nov 2009. Binary logistic regression was used to assess association between characteristics and discontinuation. Results During the study period, 79 patients were prescribed orlistat (81% female, median age 17 years). Unplanned medication discontinuation rates for orlistat were 52% and 77% at 1 and 3-months. Almost 20% of patients were co-prescribed an anti-depressant. One month unplanned medication discontinuation was significantly lower in the least deprived group (SIMD 1–2 compared to SIMD 9–10 OR 0.09 (95% CI0.01 – 0.83)) and those co-prescribed at least one other medication. At 3 months, discontinuation was higher in young people (≥17 yr versus, OR 3.07 (95% CI1.03 – 9.14)). Read codes were recorded for digestive, respiratory and urinary symptoms around the time of discontinuation for 24% of patients. Urinary retention was reported for 7.6% of patients. Conclusions Identification of unplanned medication discontinuation using large primary care datasets may be a useful tool for pharmacovigilance signal generation and detection of potential ADRs in children and young people. PMID:24594374

Risk factors for discontinuation of insulin pump therapy in pediatric and young adult patients.

PubMed

Kostev, Karel; Rockel, Timo; Rosenbauer, Joachim; Rathmann, Wolfgang

2014-12-01

Previous studies have shown that only a small number of pediatric and young adult patients discontinue pump therapy, but risk factors for discontinuation are unclear. To identify characteristics of pediatric and young adult patients with pump therapy which are associated with discontinuation of treatment. Retrospective cohort study using a representative nationwide database (LRx; IMS Health) in Germany covering >80% of all prescriptions to members of statutory health insurances in 2008-2011. All patients (age group <25 years) with new prescriptions of insulin pumps were identified (2009-2010) and were followed for 12 months. Overall, 2452 new pump users were identified, of whom 177 (7.2%) switched to other forms of insulin therapy within 12 months. In multivariate logistic regression, younger age (<6 years; reference 18 to <25 years: Odds ratio, OR, 95% CI: 0.36; 0.17-0.74) and use of teflon needles (reference steel needles: OR, 95% CI: 0.59; 0.41-0.83) were related to a lower odds of pump discontinuation. A non-significant trend was found for male sex (OR, 95% CI: 0.75; 0.52-1.08). Prescriptions of thyroid therapeutics (ATC H03A: OR, 95% CI: 1.79; 1.23-2.61) and antiepileptics (N03: OR, 95% CI: 3.14; 1.49-6.59) were significantly associated with discontinuation of pump therapy. About 93% of pediatric and young adult patients maintained insulin pump therapy within 12 months. Age <6 years, male sex and teflon needle use were associated with a lower risk of discontinuation. Thyroid therapy (indicating autoimmunity) and antiepileptic drug prescriptions were associated with a higher likelihood for discontinuation of insulin pump treatment. Copyright © 2014 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.

27 CFR 555.128 - Discontinuance of business.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2013-04-01 2013-04-01 false Discontinuance of business... Discontinuance of business. Where an explosive materials business or operations is discontinued and succeeded by... such facts and shall be delivered to the successor. Where discontinuance of the business or operations...

27 CFR 555.128 - Discontinuance of business.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2014-04-01 2014-04-01 false Discontinuance of business... Discontinuance of business. Where an explosive materials business or operations is discontinued and succeeded by... such facts and shall be delivered to the successor. Where discontinuance of the business or operations...

27 CFR 555.128 - Discontinuance of business.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Discontinuance of business. Where an explosive materials business or operations is discontinued and succeeded by... such facts and shall be delivered to the successor. Where discontinuance of the business or operations...

27 CFR 478.127 - Discontinuance of business.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2014-04-01 2014-04-01 false Discontinuance of business... Records § 478.127 Discontinuance of business. Where a licensed business is discontinued and succeeded by a... be delivered to the successor. Where discontinuance of the business is absolute, the records shall be...

27 CFR 478.57 - Discontinuance of business.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2014-04-01 2014-04-01 false Discontinuance of business... Licenses § 478.57 Discontinuance of business. (a) Where a firearm or ammunition business is either discontinued or succeeded by a new owner, the owner of the business discontinued or succeeded shall within 30...

27 CFR 478.127 - Discontinuance of business.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2013-04-01 2013-04-01 false Discontinuance of business... Records § 478.127 Discontinuance of business. Where a licensed business is discontinued and succeeded by a... be delivered to the successor. Where discontinuance of the business is absolute, the records shall be...

27 CFR 478.57 - Discontinuance of business.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2013-04-01 2013-04-01 false Discontinuance of business... Licenses § 478.57 Discontinuance of business. (a) Where a firearm or ammunition business is either discontinued or succeeded by a new owner, the owner of the business discontinued or succeeded shall within 30...

27 CFR 478.57 - Discontinuance of business.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Licenses § 478.57 Discontinuance of business. (a) Where a firearm or ammunition business is either discontinued or succeeded by a new owner, the owner of the business discontinued or succeeded shall within 30...

A Streaming Language Implementation of the Discontinuous Galerkin Method

NASA Technical Reports Server (NTRS)

Barth, Timothy; Knight, Timothy

2005-01-01

We present a Brook streaming language implementation of the 3-D discontinuous Galerkin method for compressible fluid flow on tetrahedral meshes. Efficient implementation of the discontinuous Galerkin method using the streaming model of computation introduces several algorithmic design challenges. Using a cycle-accurate simulator, performance characteristics have been obtained for the Stanford Merrimac stream processor. The current Merrimac design achieves 128 Gflops per chip and the desktop board is populated with 16 chips yielding a peak performance of 2 Teraflops. Total parts cost for the desktop board is less than $20K. Current cycle-accurate simulations for discretizations of the 3-D compressible flow equations yield approximately 40-50% of the peak performance of the Merrimac streaming processor chip. Ongoing work includes the assessment of the performance of the same algorithm on the 2 Teraflop desktop board with a target goal of achieving 1 Teraflop performance.

Etiology of Ibrutinib Discontinuation and Outcomes in Chronic Lymphocytic Leukemia Patients

PubMed Central

Maddocks, Kami J.; Ruppert, Amy S.; Lozanski, Gerard; Heerema, Nyla A.; Zhao, Weiqiang; Abruzzo, Lynne; Lozanski, Arletta; Davis, Melanie; Gordon, Amber; Smith, Lisa L.; Mantel, Rose; Jones, Jeffrey A.; Flynn, Joseph M.; Jaglowski, Samantha M.; Andritsos, Leslie A.; Awan, Farrukh; Blum, Kristie A.; Grever, Michael R.; Johnson, Amy J.; Byrd, John C.; Woyach, Jennifer A.

2015-01-01

Importance The Bruton’s Tyrosine Kinase inhibitor ibrutinib is effective in patients with chronic lymphocytic leukemia (CLL). Reasons for discontinuation from this drug and outcomes following discontinuation have not been evaluated outside of clinical trials with relatively short follow-up. Objective To determine features associated with discontinuation of ibrutinib and outcomes. Design 308 patients participating in four sequential trials of ibrutinib were included. These trials accrued patients included in this analysis from May 2010 until April 2014, and data were locked in June 2014. Setting The Ohio State University Comprehensive Cancer Center Participants Patients with CLL enrolled on 4 sequential clinical trials. Main Outcome Measure Patients were evaluated for time to discontinuation, reasons for discontinuation, and survival following discontinuation. For patients who discontinued due to progression, targeted deep sequencing was performed in samples at baseline and relapse. Results With a median follow-up of 20 months, 232 patients remain on therapy, 31 have discontinued because of progression, and 45 have discontinued for other reasons. Disease progression includes Richter’s transformation or progressive CLL. Richter’s appeared to occur early and CLL progressions later (cumulative incidence at 12 months: 4.5% (95% CI: 2.0% to 7.0%) and 0.3% (95% CI: 0% to 1.0%), respectively). Median survival following Richter’s transformation was 3.5 months (95% CI: 0.3–6.0), and 17.6 months (95% CI: 4.7-not reached) following CLL progression. Sequencing on peripheral blood from 8 patients with Richter’s transformation revealed 2 with mutations in BTK, and a lymph node sample showed no mutations in BTK or PLCγ2. Deep sequencing on 11 patients with CLL progression revealed BTK or PLCγ2 mutations in all. These mutations were not identified pre-treatment in any patient. Conclusions and Relevance This single institution experience with ibrutinib confirms it to

Management applications of discontinuity theory

USGS Publications Warehouse

Angeler, David G.; Allen, Craig R.; Barichievy, Chris; Eason, Tarsha; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Gunderson, Lance H.; Knutson, Melinda; Nash, Kirsty L.; Nelson, R. John; Nystrom, Magnus; Spanbauer, Trisha; Stow, Craig A.; Sundstrom, Shana M.

2015-01-01

Human impacts on the environment are multifaceted and can occur across distinct spatiotemporal scales. Ecological responses to environmental change are therefore difficult to predict, and entail large degrees of uncertainty. Such uncertainty requires robust tools for management to sustain ecosystem goods and services and maintain resilient ecosystems.We propose an approach based on discontinuity theory that accounts for patterns and processes at distinct spatial and temporal scales, an inherent property of ecological systems. Discontinuity theory has not been applied in natural resource management and could therefore improve ecosystem management because it explicitly accounts for ecological complexity.Synthesis and applications. We highlight the application of discontinuity approaches for meeting management goals. Specifically, discontinuity approaches have significant potential to measure and thus understand the resilience of ecosystems, to objectively identify critical scales of space and time in ecological systems at which human impact might be most severe, to provide warning indicators of regime change, to help predict and understand biological invasions and extinctions and to focus monitoring efforts. Discontinuity theory can complement current approaches, providing a broader paradigm for ecological management and conservation.

Incidence and predictors of single drug discontinuation according to the presence of HCV coinfection in HIV patients from the ICONA Foundation Cohort Study.

PubMed

Leone, Sebastiano; Shanyinde, Milensu; Cozzi Lepri, Alessandro; Lampe, Fiona C; Caramello, Pietro; Costantini, Andrea; Giacometti, Andrea; De Luca, Andrea; Cingolani, Antonella; Ceccherini Silberstein, Francesca; Puoti, Massimo; Gori, Andrea; d'Arminio Monforte, Antonella

2018-05-01

To evaluate incidence rates of and predictors for any antiretroviral (ART) drug discontinuation by HCV infection status in a large Italian cohort of HIV infected patients. All patients enrolled in ICONA who started combination antiretroviral therapy (cART) containing abacavir or tenofovir or emtricitabine or lamivudine plus efavirenz or rilpivirine or atazanavir/r or darunavir/r (DRV/r) or lopinavir/r or dolutegravir or elvitegravir or raltegravir were included. Multivariate Poisson regression models were used to determine factors independently associated with single ART drug discontinuation. Inverse probability weighting method to control for potential informative censoring was applied. Data from 10,637 patients were analyzed and 1,030 (9.7%) were HCV-Ab positive. Overall, there were 15,464 ART discontinuations due to any reason in 82,415.9 person-years of follow-up (PYFU) for an incidence rate (IR) of 18.8 (95% confidence interval [95%CI] 18.5-19.1) per 100 PYFU. No difference in IR of ART discontinuation due to any reason between HCV-infected and -uninfected patients was found. In a multivariable Poisson regression model, HCV-infected participants were at higher risk of darunavir/r discontinuation due to any reason (adjusted incidence rate ratio = 1.5, 95%CI 1.01-2.22, p value = 0.045) independently of demographics, HIV-related, ART and life-style factors. Among DRV/r treated patients, we found that HCV-viremic patients had twice the risk of ART discontinuation due to any reason than HCV-aviremic patients. In conclusion, HIV/HCV coinfected patients had a marginal risk increase of DRV/r discontinuation due to any reason compared with those without coinfection.

40 CFR 159.167 - Discontinued studies.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Discontinued studies. 159.167 Section... Discontinued studies. The fact that a study has been discontinued before the planned termination must be reported to EPA, with the reason for termination, if submission of information concerning the study is, or...

40 CFR 159.167 - Discontinued studies.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Discontinued studies. 159.167 Section... Discontinued studies. The fact that a study has been discontinued before the planned termination must be reported to EPA, with the reason for termination, if submission of information concerning the study is, or...

When and why a colonoscopist should discontinue colonoscopy by himself?

PubMed

Gan, Tao; Yang, Jin-Lin; Wu, Jun-Chao; Wang, Yi-Ping; Yang, Li

2015-07-07

To investigate when and why a colonoscopist should discontinue incomplete colonoscopy by himself. In this cross-sectional study, 517 difficult colonoscope insertions (Grade C, Kudo's difficulty classification) screened from 37800 colonoscopy insertions were collected from April 2004 to June 2014 by three 4(th)-level (Kudo's classification) colonoscopists. The following common factors for the incomplete insertion were excluded: structural obstruction of the colon or rectum, insufficient colon cleansing, discontinuation due to patient's discomfort or pain, severe colon disease with a perforation risk (e.g., severe ischemic colonopathy). All the excluded patients were re-scheduled if permission was obtained from the patients whose intubation had failed. If the repeat intubations were still a failure because of the difficult operative techniques, those patients were also included in this study. The patient's age, sex, anesthesia and colonoscope type were recorded before colonoscopy. During the colonoscopic examination, the influencing factors of fixation, tortuosity, laxity and redundancy of the colon were assessed, and the insertion time (> 10 min or ≤ 10 min) were registered. The insertion time was analyzed by t-test, and other factors were analyzed by univariate and multivariate logistic regression. Three hundred and twenty-two (62.3%) of the 517 insertions were complete in the colonoscope insertion into the ileocecum, but 195 (37.7%) failed in the insertion. Fixation, tortuosity, laxity or redundancy occurred during the colonoscopic examination. Multivariate logistic regression analysis revealed that fixation (OR = 0.06, 95%CI: 0.03-0.16, P < 0.001) and tortuosity (OR = 0.04, 95%CI: 0.02-0.08, P < 0.001) were significantly related to the insertion into the ileocecum in the left hemicolon; multivariate logistic regression analysis also revealed that fixation (OR = 0.16, 95%CI: 0.06-0.39, P < 0.001), tortuosity (OR 0.23, 95%CI: 0.13-0.43, P < 0.001), redundancy (OR

Local Existence of MHD Contact Discontinuities

NASA Astrophysics Data System (ADS)

Morando, Alessandro; Trakhinin, Yuri; Trebeschi, Paola

2018-05-01

We prove the local-in-time existence of solutions with a contact discontinuity of the equations of ideal compressible magnetohydrodynamics (MHD) for two dimensional planar flows provided that the Rayleigh-Taylor sign condition {[partial p/partial N] <0 } on the jump of the normal derivative of the pressure is satisfied at each point of the initial discontinuity. MHD contact discontinuities are characteristic discontinuities with no flow across the discontinuity for which the pressure, the magnetic field and the velocity are continuous whereas the density and the entropy may have a jump. This paper is a natural completion of our previous analysis (Morando et al. in J Differ Equ 258:2531-2571, 2015) where the well-posedness in Sobolev spaces of the linearized problem was proved under the Rayleigh-Taylor sign condition satisfied at each point of the unperturbed discontinuity. The proof of the resolution of the nonlinear problem given in the present paper follows from a suitable tame a priori estimate in Sobolev spaces for the linearized equations and a Nash-Moser iteration.

Quasi-experimental study designs series-paper 7: assessing the assumptions.

PubMed

Bärnighausen, Till; Oldenburg, Catherine; Tugwell, Peter; Bommer, Christian; Ebert, Cara; Barreto, Mauricio; Djimeu, Eric; Haber, Noah; Waddington, Hugh; Rockers, Peter; Sianesi, Barbara; Bor, Jacob; Fink, Günther; Valentine, Jeffrey; Tanner, Jeffrey; Stanley, Tom; Sierra, Eduardo; Tchetgen, Eric Tchetgen; Atun, Rifat; Vollmer, Sebastian

2017-09-01

Quasi-experimental designs are gaining popularity in epidemiology and health systems research-in particular for the evaluation of health care practice, programs, and policy-because they allow strong causal inferences without randomized controlled experiments. We describe the concepts underlying five important quasi-experimental designs: Instrumental Variables, Regression Discontinuity, Interrupted Time Series, Fixed Effects, and Difference-in-Differences designs. We illustrate each of the designs with an example from health research. We then describe the assumptions required for each of the designs to ensure valid causal inference and discuss the tests available to examine the assumptions. Copyright © 2017 Elsevier Inc. All rights reserved.

Healthcare resource utilization following switch or discontinuation in multiple sclerosis patients on disease modifying drugs.

PubMed

Reynolds, Matthew W; Stephen, Reejis; Seaman, Chris; Rajagopalan, Kitty

2010-03-01

The objective of this study was to explore the cost and utilization in the period following discontinuations or switches of disease modifying drugs (DMDs) for patients with multiple sclerosis (MS). Secondary objectives included an assessment of the time to switch or discontinuation from index DMD treatment. Cases were defined as a billed MS diagnosis in continuously enrolled patients initiated with interferon-beta1a IM, interferon-beta1b SC, glatiramer acetate, and interferon-beta1a SC found in the PharMetrics Patient-Centric Database. Information on patient demographics, diagnoses, procedures, pharmacy-dispensed drugs, and costs was extracted; reasons for discontinuation and expenses outside of the healthcare system were not available. Treatment discontinuations and switches between study drugs were defined using pharmacy prescription patterns and analyzed by descriptive and regression methods. The non-pharmacy medical costs in the 18 months following switching or discontinuation were compared to the costs in a randomly selected similar period for those patients who did not switch or discontinue these agents. A total of 5,772 MS patients were continuously enrolled and were treated with one or more of the four drugs of interest, and about half of these patients switched drugs or discontinued treatment for at least 90 days. Patients initiated with interferon-beta1b SC were more likely to discontinue treatment compared to interferon-beta1a IM users. Non-pharmaceutical medical costs were highest for those switching treatments followed by those discontinuing DMDs in the 18 months following a switch or discontinuation, compared to persistent users of these drugs. Interferon beta1b SC initiators had higher costs following changes or discontinuations, while glatiramer acetate and interferon-beta1a SC users had lower subsequent costs compared to interferon-beta1a IM users. Unfortunately, the reasons for stopping the initial treatment cannot be determined from analysis of

Neural Network and Regression Methods Demonstrated in the Design Optimization of a Subsonic Aircraft

NASA Technical Reports Server (NTRS)

Hopkins, Dale A.; Lavelle, Thomas M.; Patnaik, Surya

2003-01-01

The neural network and regression methods of NASA Glenn Research Center s COMETBOARDS design optimization testbed were used to generate approximate analysis and design models for a subsonic aircraft operating at Mach 0.85 cruise speed. The analytical model is defined by nine design variables: wing aspect ratio, engine thrust, wing area, sweep angle, chord-thickness ratio, turbine temperature, pressure ratio, bypass ratio, fan pressure; and eight response parameters: weight, landing velocity, takeoff and landing field lengths, approach thrust, overall efficiency, and compressor pressure and temperature. The variables were adjusted to optimally balance the engines to the airframe. The solution strategy included a sensitivity model and the soft analysis model. Researchers generated the sensitivity model by training the approximators to predict an optimum design. The trained neural network predicted all response variables, within 5-percent error. This was reduced to 1 percent by the regression method. The soft analysis model was developed to replace aircraft analysis as the reanalyzer in design optimization. Soft models have been generated for a neural network method, a regression method, and a hybrid method obtained by combining the approximators. The performance of the models is graphed for aircraft weight versus thrust as well as for wing area and turbine temperature. The regression method followed the analytical solution with little error. The neural network exhibited 5-percent maximum error over all parameters. Performance of the hybrid method was intermediate in comparison to the individual approximators. Error in the response variable is smaller than that shown in the figure because of a distortion scale factor. The overall performance of the approximators was considered to be satisfactory because aircraft analysis with NASA Langley Research Center s FLOPS (Flight Optimization System) code is a synthesis of diverse disciplines: weight estimation, aerodynamic

Discontinuous permeable adsorptive barrier design and cost analysis: a methodological approach to optimisation.

PubMed

Santonastaso, Giovanni Francesco; Bortone, Immacolata; Chianese, Simeone; Di Nardo, Armando; Di Natale, Michele; Erto, Alessandro; Karatza, Despina; Musmarra, Dino

2017-09-19

The following paper presents a method to optimise a discontinuous permeable adsorptive barrier (PAB-D). This method is based on the comparison of different PAB-D configurations obtained by changing some of the main PAB-D design parameters. In particular, the well diameters, the distance between two consecutive passive wells and the distance between two consecutive well lines were varied, and a cost analysis for each configuration was carried out in order to define the best performing and most cost-effective PAB-D configuration. As a case study, a benzene-contaminated aquifer located in an urban area in the north of Naples (Italy) was considered. The PAB-D configuration with a well diameter of 0.8 m resulted the best optimised layout in terms of performance and cost-effectiveness. Moreover, in order to identify the best configuration for the remediation of the aquifer studied, a comparison with a continuous permeable adsorptive barrier (PAB-C) was added. In particular, this showed a 40% reduction of the total remediation costs by using the optimised PAB-D.

Special discontinuities in nonlinearly elastic media

NASA Astrophysics Data System (ADS)

Chugainova, A. P.

2017-06-01

Solutions of a nonlinear hyperbolic system of equations describing weakly nonlinear quasitransverse waves in a weakly anisotropic elastic medium are studied. The influence of small-scale processes of dissipation and dispersion is investigated. The small-scale processes determine the structure of discontinuities (shocks) and a set of discontinuities with a stationary structure. Among the discontinuities with a stationary structure, there are special ones that, in addition to relations following from conservation laws, satisfy additional relations required for the existence of their structure. In the phase plane, the structure of such discontinuities is represented by an integral curve joining two saddles. Special discontinuities lead to nonunique self-similar solutions of the Riemann problem. Asymptotics of non-self-similar problems for equations with dissipation and dispersion are found numerically. These asymptotics correspond to self-similar solutions of the problems.

Reasons and correlates of contraceptive discontinuation in Kuwait.

PubMed

Shah, N M; Shah, M A; Chowdhury, R I; Menon, I

2007-09-01

(1) To examine the probability of discontinuation of various methods within 1, 2, and three years of use and the reasons for discontinuation; 2) to analyse the socio-demographic correlates of discontinuation. Data from a survey of Kuwaiti women in reproductive ages conducted in 1999 were used. Information on duration of use of modern and traditional methods, and reasons for discontinuation during the 72 months before the survey were analysed. Probabilities of discontinuation were estimated through multiple decrement life table analysis. After 1 year, 30% of modern and 40% of traditional method users had discontinued; after 3 years, discontinuation increased to 66 and 70%, respectively. After 36 months, only 40% of IUD users discontinued compared with 74% of oral contraceptive users. The desire to become pregnant was the leading reason for discontinuation of most modern methods, while method failure was an equally important reason for traditional methods. Discontinuation was significantly more frequent among higher parity, non-working and Bedouin women, and among those who said Islam disapproves of contraception. Contraception is used largely for spacing. More than two-thirds of the women studied had discontinued most methods after three years, except the IUD, which was used only by about 10% of them. Traditional methods are often discontinued due to method failure and may result in an unintended pregnancy. Better counselling is warranted for traditional methods. Health care for managing side effects of modern methods also needs improvement.

Factors associated with poor satisfaction with treatment and trial discontinuation in chronic schizophrenia.

PubMed

Schoemaker, Joep H; Vingerhoets, Ad J J M; Emsley, Robin A

2018-06-05

IntroductionDespite consistently high discontinuation rates due to withdrawal of consent (WOC) and insufficient therapeutic effect (ITE) in schizophrenia trials, insight into the underlying factors contributing to poor satisfaction with treatment and dropout is limited. A better understanding of these factors could help to improve trial design and completion rates. Using data from 1,136 trial participants with schizophrenia or schizoaffective disorder, we explored associations between predictor variables with (1) dropout due to WOC and ITE and (2) satisfaction with treatment among patients and investigators by means of hierarchic multiple regression analyses. ITE was associated with poor clinical improvement, poor investigator satisfaction with treatment, and poor patient insight into their own disease, whereas WOC only showed a meaningful association with poor patient satisfaction with treatment. Investigator satisfaction with treatment appeared most strongly associated with Positive and Negative Syndrome Scale (PANSS) positive factor endpoint scores, whereas patient satisfaction with treatment was best predicted by the endpoint score on the PANSS emotional distress factor. The occurrence of severe side effects showed no meaningful association to satisfaction with treatment among investigators and patients, and neither did a patient's experienced psychopathology, nor their self-rating of functional impairment. Whereas trial discontinuation due to ITE is associated with poor treatment effectiveness, a patient's decision to withdraw from an antipsychotic trial remains unpredictable and may occur even when the investigator observes a global clinical improvement and is satisfied with the treatment.

Abrupt opium discontinuation has no significant triggering effect on acute myocardial infarction.

PubMed

Masoomi, Mohammad; Zare, Jahangir; Nasri, Hamidreza; Mirzazadeh, Ali; Sheikhvatan, Mehrdad

2011-04-01

A deleterious effect of withdrawal symptoms due to abrupt discontinuation of opium on the cardiovascular system is one of the recent interesting topics in the cardiovascular field. The current study hypothesized that the withdrawal syndrome due to discontinuing opium might be an important trigger for the appearance of acute myocardial infarction. Eighty-one opium-addicted individuals who were candidates for cardiovascular clinical evaluation and consecutively hospitalized in the coronary care unit (CCU) ward of Shafa Hospital in Kerman between January and July 2009 were included in the study and categorized in the case group, including patients experiencing withdrawal symptoms within 6-12 h after the reduced or discontinued use of opium according to the Diagnostic and Statistical Manual of Mental Disorders-revised IV version (DSM-IV-R) criteria for opium dependence and withdrawal, and the control group, without opium withdrawal symptoms. The appearance of acute myocardial infarction was compared between the two groups using multivariable regression models. Acute myocardial infarction occurred in 50.0% of those with withdrawal symptoms and in 45.1% of patients without evidence of opium withdrawal (P = 0.669). Multivariable analysis showed that opium withdrawal symptoms were not a trigger for acute myocardial infarction adjusting for demographic characteristics, marital status, education level and common coronary artery disease risk profiles [odds ratio (OR) = 0.920, 95% confidence interval (CI) = 0.350-2.419, P = 0.866]. Also, daily dose of opium before reducing or discontinuing use did not predict the appearance of myocardial infarction in the presence of confounder variables (OR = 0.975, 95% CI = 0.832-1.143, P = 0.755). Withdrawal syndrome due to abrupt discontinuation of opium does not have a triggering role for appearance of acute myocardial infarction.

Neural Network and Regression Approximations in High Speed Civil Transport Aircraft Design Optimization

NASA Technical Reports Server (NTRS)

Patniak, Surya N.; Guptill, James D.; Hopkins, Dale A.; Lavelle, Thomas M.

1998-01-01

Nonlinear mathematical-programming-based design optimization can be an elegant method. However, the calculations required to generate the merit function, constraints, and their gradients, which are frequently required, can make the process computational intensive. The computational burden can be greatly reduced by using approximating analyzers derived from an original analyzer utilizing neural networks and linear regression methods. The experience gained from using both of these approximation methods in the design optimization of a high speed civil transport aircraft is the subject of this paper. The Langley Research Center's Flight Optimization System was selected for the aircraft analysis. This software was exercised to generate a set of training data with which a neural network and a regression method were trained, thereby producing the two approximating analyzers. The derived analyzers were coupled to the Lewis Research Center's CometBoards test bed to provide the optimization capability. With the combined software, both approximation methods were examined for use in aircraft design optimization, and both performed satisfactorily. The CPU time for solution of the problem, which had been measured in hours, was reduced to minutes with the neural network approximation and to seconds with the regression method. Instability encountered in the aircraft analysis software at certain design points was also eliminated. On the other hand, there were costs and difficulties associated with training the approximating analyzers. The CPU time required to generate the input-output pairs and to train the approximating analyzers was seven times that required for solution of the problem.

Regression approaches in the test-negative study design for assessment of influenza vaccine effectiveness.

PubMed

Bond, H S; Sullivan, S G; Cowling, B J

2016-06-01

Influenza vaccination is the most practical means available for preventing influenza virus infection and is widely used in many countries. Because vaccine components and circulating strains frequently change, it is important to continually monitor vaccine effectiveness (VE). The test-negative design is frequently used to estimate VE. In this design, patients meeting the same clinical case definition are recruited and tested for influenza; those who test positive are the cases and those who test negative form the comparison group. When determining VE in these studies, the typical approach has been to use logistic regression, adjusting for potential confounders. Because vaccine coverage and influenza incidence change throughout the season, time is included among these confounders. While most studies use unconditional logistic regression, adjusting for time, an alternative approach is to use conditional logistic regression, matching on time. Here, we used simulation data to examine the potential for both regression approaches to permit accurate and robust estimates of VE. In situations where vaccine coverage changed during the influenza season, the conditional model and unconditional models adjusting for categorical week and using a spline function for week provided more accurate estimates. We illustrated the two approaches on data from a test-negative study of influenza VE against hospitalization in children in Hong Kong which resulted in the conditional logistic regression model providing the best fit to the data.

Why do patients discontinue fertility treatment? A systematic review of reasons and predictors of discontinuation in fertility treatment.

PubMed

Gameiro, S; Boivin, J; Peronace, L; Verhaak, C M

2012-01-01

BACKGROUND Chances of achieving parenthood are high for couples who undergo fertility treatment. However, many choose to discontinue before conceiving. A systematic review was conducted to investigate patients' stated reasons for and predictors of discontinuation at five fertility treatment stages. METHODS Six databases were systematically searched. Search-terms referred to fertility treatment and discontinuation. Studies reporting on patients' stated reasons for or predictors of treatment discontinuation were included. A list of all reasons for discontinuation presented in each study was made, different categories of reasons were defined and the percentage of selections of each category was calculated. For each predictor, it was noted how many studies investigated it and how many found a positive and/or negative association with discontinuation. RESULTS The review included 22 studies that sampled 21 453 patients from eight countries. The most selected reasons for discontinuation were: postponement of treatment (39.18%, postponement of treatment or unknown 19.17%), physical and psychological burden (19.07%, psychological burden 14%, physical burden 6.32%), relational and personal problems (16.67%, personal reasons 9.27%, relational problems 8.83%), treatment rejection (13.23%) and organizational (11.68%) and clinic (7.71%) problems. Some reasons were common across stages (e.g. psychological burden). Others were stage-specific (e.g. treatment rejection during workup). None of the predictors reported were consistently associated with discontinuation. CONCLUSIONS Much longitudinal and theory led research is required to explain discontinuation. Meanwhile, treatment burden should be addressed by better care organization and support for patients. Patients should be well informed, have the opportunity to discuss values and worries about treatment and receive advice to decide about continuing treatment.

Why do patients discontinue fertility treatment? A systematic review of reasons and predictors of discontinuation in fertility treatment

PubMed Central

Gameiro, S.; Boivin, J.; Peronace, L.; Verhaak, C.M.

2012-01-01

BACKGROUND Chances of achieving parenthood are high for couples who undergo fertility treatment. However, many choose to discontinue before conceiving. A systematic review was conducted to investigate patients' stated reasons for and predictors of discontinuation at five fertility treatment stages. METHODS Six databases were systematically searched. Search-terms referred to fertility treatment and discontinuation. Studies reporting on patients' stated reasons for or predictors of treatment discontinuation were included. A list of all reasons for discontinuation presented in each study was made, different categories of reasons were defined and the percentage of selections of each category was calculated. For each predictor, it was noted how many studies investigated it and how many found a positive and/or negative association with discontinuation. RESULTS The review included 22 studies that sampled 21 453 patients from eight countries. The most selected reasons for discontinuation were: postponement of treatment (39.18%, postponement of treatment or unknown 19.17%), physical and psychological burden (19.07%, psychological burden 14%, physical burden 6.32%), relational and personal problems (16.67%, personal reasons 9.27%, relational problems 8.83%), treatment rejection (13.23%) and organizational (11.68%) and clinic (7.71%) problems. Some reasons were common across stages (e.g. psychological burden). Others were stage-specific (e.g. treatment rejection during workup). None of the predictors reported were consistently associated with discontinuation. CONCLUSIONS Much longitudinal and theory led research is required to explain discontinuation. Meanwhile, treatment burden should be addressed by better care organization and support for patients. Patients should be well informed, have the opportunity to discuss values and worries about treatment and receive advice to decide about continuing treatment. PMID:22869759

Investigation of Efavirenz Discontinuation in Multi-ethnic Populations of HIV-positive Individuals by Genetic Analysis.

PubMed

Cummins, Nathan W; Neuhaus, Jacqueline; Chu, Haitao; Neaton, James; Wyen, Christoph; Rockstroh, Jürgen K; Skiest, Daniel J; Boyd, Mark A; Khoo, Saye; Rotger, Margalida; Telenti, Amalio; Weinshilboum, Richard; Badley, Andrew D

2015-07-01

Efavirenz (EFV) based antiretroviral therapy is expanding worldwide. However discontinuation of EFV containing regimens is common in some patients, particularly black patients, due most often to neuropsychiatric side effects. These adverse drug effects often result in premature drug discontinuation, as well as considerable morbidity. We genotyped CYP2A6, CYP2B6 and CYP3A4, which encode enzymes principally involved in EFV metabolism, from patients enrolled in the multinational SMART, FIRST and ESPRIT studies, for whom outcome data of treatment adherence was available. Patients with loss or decrease of function single nucleotide polymorphisms (SNPs) in the above genes were assigned a risk score based upon the number of SNPs present weighted relative to whether CYP2B6 (main metabolism pathway) and/or CYP2A6 and CYP3A4 (accessory pathways) were involved. Cox regression models were used to study the association between high genetic risk and time from initiation to EFV discontinuation. Failure was defined as discontinuation of an antiretroviral regimen other than for virologic failure or protocol determined discontinuation. Patients with highest pharmacogenetic risk, as defined by cumulative SNPs in CYP2A6, CYP2B6 and CYP3A4, have an increased risk of discontinuation of EFV containing therapy compared to patients with lower genetic risk scores (adjusted HR 1.9, 95% CI 1.2, 3.1, P = 0.009). High genetic risk score was not associated with an increased risk of discontinuing atazanavir or nevirapine. High genetic risk was present more often in blacks compared to non-blacks (Adjusted OR 4.5, 95% CI: 1.9,10.5), and treatment discontinuation was also increased in blacks overall (Adjusted HR 1.4, 95% CI 1.0, 1.9). However, high genetic risk was more associated with treatment discontinuation than race alone for both blacks (Adjusted OR 1.9, 95% CI 0.8, 4.8) and non-blacks (Adjusted OR 5.3, 95% CI 1.5, 18.0). Premature discontinuation of ART delays the time to effective long

Light propagation with phase discontinuities: generalized laws of reflection and refraction.

PubMed

Yu, Nanfang; Genevet, Patrice; Kats, Mikhail A; Aieta, Francesco; Tetienne, Jean-Philippe; Capasso, Federico; Gaburro, Zeno

2011-10-21

Conventional optical components rely on gradual phase shifts accumulated during light propagation to shape light beams. New degrees of freedom are attained by introducing abrupt phase changes over the scale of the wavelength. A two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint such phase discontinuities on propagating light as it traverses the interface between two media. Anomalous reflection and refraction phenomena are observed in this regime in optically thin arrays of metallic antennas on silicon with a linear phase variation along the interface, which are in excellent agreement with generalized laws derived from Fermat's principle. Phase discontinuities provide great flexibility in the design of light beams, as illustrated by the generation of optical vortices through use of planar designer metallic interfaces.

Change in Stiffness of Pavement Layers in the Linear Discontinuous Deformation Area

NASA Astrophysics Data System (ADS)

Grygierek, Marcin

2017-10-01

The underground mining exploitation causes deformations on the surface of the area which are classified as continuous or discontinuous. Mining deformations cause loosening or compression of the subsoil. Loosening has an impact on the reduction of the subsoil stiffness. As a result the reduction of subsoil stiffness causes loosening of construction layers built in that subsoil. Pavement is a specific case. If there happens to be loosening then the fatigue life of pavement is reduced and premature damages can be observed such as fatigue cracks or/and structural deformation. Discontinuous deformations are an especially interesting case. They not only cause the reduction of the stiffness of the subsoil and pavement layers but also cause rapid deterioration in roughness. Change of roughness is very dangerous especially on fast roads such as a highway. Lately there can be observed the so called linear discontinuous surface deformations in the lanes in the mining area. Unfortunately, the ‘in situ’ research, presenting experiments on the effect of linear discontinuous deformations on the pavement, is in short supply. It is especially crucial with regard to the design of pavement reinforcement and the specification of optimal length of the reinforced part of the road. The article presents the results of ‘in situ’ tests carried out on the chosen pavements where the so called linear discontinuous surface deformation has appeared. The genesis of the damage is connected with the underground mining exploitation. Falling Weight Deflectometer (FWD) has been used in researches. Measuring points were carried out with high frequency which helped to acquire a very interesting distribution of deflections. The distribution of deflections well shows the impact of linear discontinuous deformation on the changes in stiffness pavement layers. In the analysis of data from FWD there has been used back calculation which worked modulus of layers out. The results of researches and

Fatigue design of a cellular phone folder using regression model-based multi-objective optimization

NASA Astrophysics Data System (ADS)

Kim, Young Gyun; Lee, Jongsoo

2016-08-01

In a folding cellular phone, the folding device is repeatedly opened and closed by the user, which eventually results in fatigue damage, particularly to the front of the folder. Hence, it is important to improve the safety and endurance of the folder while also reducing its weight. This article presents an optimal design for the folder front that maximizes its fatigue endurance while minimizing its thickness. Design data for analysis and optimization were obtained experimentally using a test jig. Multi-objective optimization was carried out using a nonlinear regression model. Three regression methods were employed: back-propagation neural networks, logistic regression and support vector machines. The AdaBoost ensemble technique was also used to improve the approximation. Two-objective Pareto-optimal solutions were identified using the non-dominated sorting genetic algorithm (NSGA-II). Finally, a numerically optimized solution was validated against experimental product data, in terms of both fatigue endurance and thickness index.

Discontinuity stresses in metallic pressure vessels

NASA Technical Reports Server (NTRS)

1971-01-01

The state of the art, criteria, and recommended practices for the theoretical and experimental analyses of discontinuity stresses and their distribution in metallic pressure vessels for space vehicles are outlined. The applicable types of pressure vessels include propellant tanks ranging from main load-carrying integral tank structure to small auxiliary tanks, storage tanks, solid propellant motor cases, high pressure gas bottles, and pressurized cabins. The major sources of discontinuity stresses are discussed, including deviations in geometry, material properties, loads, and temperature. The advantages, limitations, and disadvantages of various theoretical and experimental discontinuity analysis methods are summarized. Guides are presented for evaluating discontinuity stresses so that pressure vessel performance will not fall below acceptable levels.

38 CFR 21.5835 - Specific discontinuance dates.

Code of Federal Regulations, 2011 CFR

2011-07-01

... individual. If an individual dies— (1) VA will discontinue educational assistance effective the last day of... educational assistance. (2) VA will discontinue subsistence allowance effective the individual's last date of... in lieu of educational assistance, VA will discontinue educational assistance effective the date on...

38 CFR 21.5835 - Specific discontinuance dates.

Code of Federal Regulations, 2014 CFR

2014-07-01

... individual. If an individual dies— (1) VA will discontinue educational assistance effective the last day of... educational assistance. (2) VA will discontinue subsistence allowance effective the individual's last date of... in lieu of educational assistance, VA will discontinue educational assistance effective the date on...

38 CFR 21.5835 - Specific discontinuance dates.

Code of Federal Regulations, 2013 CFR

2013-07-01

... individual. If an individual dies— (1) VA will discontinue educational assistance effective the last day of... educational assistance. (2) VA will discontinue subsistence allowance effective the individual's last date of... in lieu of educational assistance, VA will discontinue educational assistance effective the date on...

Branch point reconstructors for discontinuous light phase functions

NASA Astrophysics Data System (ADS)

Le Bigot, Eric O.; Wild, Walter J.; Kibblewhite, Edward J.

1998-09-01

The study of phase discontinuities caused by atmospheric turbulence is a recent research topic; their study might yield significant improvements in high-quality adaptive optics systems, laser weapons and laser communication. We present in this paper an introduction to discontinuities in the light phase. We also provide a geometrical description of phase discontinuities, a study of their effect on Hartmann-Shack sensor measurements, as well as algorithms for measuring discontinuous light phases and the position of phase discontinuities.

Selective serotonin reuptake inhibitor discontinuation: side effects and other factors that influence medication adherence.

PubMed

Goethe, John W; Woolley, Stephen B; Cardoni, Alex A; Woznicki, Brenda A; Piez, Deborah A

2007-10-01

Patients with major depression discontinue taking their antidepressants for many reasons. Although side effects are often cited as the reason for discontinuation, few prospective studies have addressed this question, and none has specifically examined discontinuation in patients with severe depression. Inpatients and outpatients treated with a selective serotonin reuptake inhibitor for major depressive disorder were identified after admission. Three months later, patients were contacted and interviewed to determine antidepressant usage and the side effects experienced, including when these were experienced and their severity. Between October 2001 and April 2003, 406 English- or Spanish-speaking patients aged 18 to 75 years were followed up. One in 4 patients discontinued the index antidepressant. Among specific side effects noted, only "change in weight" and "anxiety" were significant predictors of discontinuation after controlling for confounders. Experiencing 1 or more "extremely" bothersome side effects was associated with more than a doubling of the risk of discontinuation, but the presence of side effects and side effects less severe than "extremely" bothersome were not significant predictors. There were no differences among selective serotonin reuptake inhibitor antidepressants in either the presence/absence of side effects or in the discontinuation rates. The results suggest that the contribution of side effects to antidepressant discontinuation is more complex than previously suggested. Disparate findings from earlier studies may reflect aspects of study design, such as examining populations whose severity of depression varied widely or not controlling for important confounding factors. Future research should separately examine high-risk groups (or control for severity of depression) and carefully rule out other potential contributors to discontinuation.

Management applications of discontinuity theory | Science ...

EPA Pesticide Factsheets

1.Human impacts on the environment are multifaceted and can occur across distinct spatiotemporal scales. Ecological responses to environmental change are therefore difficult to predict, and entail large degrees of uncertainty. Such uncertainty requires robust tools for management to sustain ecosystem goods and services and maintain resilient ecosystems. 2.We propose an approach based on discontinuity theory that accounts for patterns and processes at distinct spatial and temporal scales, an inherent property of ecological systems. Discontinuity theory has not been applied in natural resource management and could therefore improve ecosystem management because it explicitly accounts for ecological complexity. 3.Synthesis and applications. We highlight the application of discontinuity approaches for meeting management goals. Specifically, discontinuity approaches have significant potential to measure and thus understand the resilience of ecosystems, to objectively identify critical scales of space and time in ecological systems at which human impact might be most severe, to provide warning indicators of regime change, to help predict and understand biological invasions and extinctions and to focus monitoring efforts. Discontinuity theory can complement current approaches, providing a broader paradigm for ecological management and conservation This manuscript provides insight on using discontinuity approaches to aid in managing complex ecological systems. In part

Risk factors associated with treatment discontinuation and down-titration in type 2 diabetes patients treated with sulfonylureas.

PubMed

Iglay, Kristy; Qiu, Ying; Steve Fan, Chun-Po; Li, Zhiyi; Tang, Jackson; Laires, Pedro

2016-09-01

Sulfonylurea therapy among patients with type 2 diabetes mellitus (T2DM) can be disrupted due to adverse events, including hypoglycemia. A retrospective study using the MarketScan claims database quantified the frequency of sulfonylurea discontinuation or down-titration and identified associated risk factors. Adult patients with an index sulfonylurea prescription between 2008 and 2012 and 1 year continuous enrollment pre- and post-index were included. Therapy changes assessed over 1 year post-index included discontinuation and down-titration. Discontinuation occurred if the date of a fill was >90 days from the end date of the preceding fill. Down-titration occurred when a fill had a lower equivalent dose than the fill on the index date. Kaplan-Meier methods estimated the probability of either discontinuation or down-titration over 12 months, and Cox regression models identified associated risk factors. A total of 104,082 sulfonylurea users were included in the study and the probability of either discontinuation or down-titration at 3, 6 and 12 months was 23.2%, 38.9%, and 52.3%, respectively. Major risk factors associated with therapy changes included post-index hypoglycemia (discontinuation hazard ratio [HR] = 1.78 [1.68, 1.89]; down-titration HR =2.79 [2.40, 3.23]) and concomitant use of insulin (discontinuation HR =1.48 [1.40, 1.57]; down-titration HR =1.82 [1.56, 2.11]). Other risk factors included younger age, female gender, use of second generation sulfonylureas, prior cardiovascular comorbidity and liver disease. The study was not able to assess unreported, potentially mild cases of hypoglycemia, nor was it able to evaluate the association between changes in therapy and HbA1c levels or body weight. More than half of T2DM patients who initiated sulfonylurea therapy discontinued or down-titrated within 1 year. Insulin use and hypoglycemia were associated with sulfonylurea therapy change.

27 CFR 40.331 - Discontinuance of operations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... operations. 40.331 Section 40.331 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... AND TUBES, AND PROCESSED TOBACCO Suspension and Discontinuance of Operations by Manufacturers § 40.331 Discontinuance of operations. Every manufacturer of tobacco products who desires to discontinue operations under...

Excursions in fluvial (dis)continuity

Treesearch

Gordon E. Grant; Jim E. O' Connor; Elizabeth Safran

2017-01-01

Lurking below the twin concepts of connectivity and disconnectivity are their first, and in someways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in...

Discontinuation of Buprenorphine Maintenance Therapy: Perspectives and Outcomes

PubMed Central

Bentzley, Brandon S.; Barth, Kelly S.; Back, Sudie E.; Book, Sarah W.

2015-01-01

Buprenorphine maintenance therapy (BMT) is increasingly the preferred opioid maintenance agent due to its reduced toxicity and availability in an office-based setting in the United States. Although BMT has been shown to be highly efficacious, it is often discontinued soon after initiation. No current systematic review has yet investigated providers’ or patients’ reasons for BMT discontinuation or the outcomes that follow. Hence, provider and patient perspectives associated with BMT discontinuation after a period of stable buprenorphine maintenance and the resultant outcomes were systematically reviewed with specific emphasis on pre-buprenorphine-taper parameters predictive of relapse following BMT discontinuation. Few identified studies address provider or patient perspectives associated with buprenorphine discontinuation. Within the studies reviewed providers with residency training in BMT were more likely to favor long term BMT instead of detoxification, and providers were likely to consider BMT discontinuation in the face of medication misuse. Patients often desired to remain on BMT because of fear of relapse to illicit opioid use if they were to discontinue BMT. The majority of patients who discontinued BMT did so involuntarily, often due to failure to follow strict program requirements, and 1 month following discontinuation, rates of relapse to illicit opioid use exceeded 50% in every study reviewed. Only lower buprenorphine maintenance dose, which may be a marker for attenuated addiction severity, predicted better outcomes across studies. Relaxed BMT program requirements and frequent counsel on the high probability of relapse if BMT is discontinued may improve retention in treatment and prevent the relapse to illicit opioid use that is likely to follow BMT discontinuation. PMID:25601365

27 CFR 478.127 - Discontinuance of business.

Code of Federal Regulations, 2010 CFR

2010-04-01

... business was located: Provided, however, Where State law or local ordinance requires the delivery of... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Records § 478.127 Discontinuance of business. Where a licensed business is discontinued and succeeded by a...

Applicability of radon emanometry in lithologically discontinuous sites contaminated by organic chemicals.

PubMed

De Miguel, Eduardo; Barrio-Parra, Fernando; Elío, Javier; Izquierdo-Díaz, Miguel; García-González, Jerónimo Emilio; Mazadiego, Luis Felipe; Medina, Rafael

2018-06-02

The applicability of radon ( 222 Rn) measurements to delineate non-aqueous phase liquids (NAPL) contamination in subsoil is discussed at a site with lithological discontinuities through a blind test. Three alpha spectroscopy monitors were used to measure radon in soil air in a 25,000-m 2 area, following a regular sampling design with a 20-m 2 grid. Repeatability and reproducibility of the results were assessed by means of duplicate measurements in six sampling positions. Furthermore, three points not affected by oil spills were sampled to estimate radon background concentration in soil air. Data histograms, Q-Q plots, variograms, and cluster analysis allowed to recognize two data populations, associated with the possible path of a fault and a lithological discontinuity. Even though the concentration of radon in soil air was dominated by this discontinuity, the characterization of the background emanation in each lithological unit allowed to distinguish areas potentially affected by NAPL, thus justifying the application of radon emanometry as a screening technique for the delineation of NAPL plumes in sites with lithological discontinuities.

27 CFR 46.138 - Discontinuance of business.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2012-04-01 2011-04-01 true Discontinuance of business. 46.138 Section 46.138 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....138 Discontinuance of business. A dealer who for any reason discontinues business is not entitled to a...

27 CFR 46.138 - Discontinuance of business.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2014-04-01 2014-04-01 false Discontinuance of business. 46.138 Section 46.138 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....138 Discontinuance of business. A dealer who for any reason discontinues business is not entitled to a...

27 CFR 31.162 - Discontinuance of business.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Discontinuance of business... and Reports § 31.162 Discontinuance of business. When a wholesale dealer in liquors who is required, under § 31.160, to file a monthly summary report discontinues business, a monthly summary report marked...

A discontinuous Galerkin method for two-dimensional PDE models of Asian options

NASA Astrophysics Data System (ADS)

Hozman, J.; Tichý, T.; Cvejnová, D.

2016-06-01

In our previous research we have focused on the problem of plain vanilla option valuation using discontinuous Galerkin method for numerical PDE solution. Here we extend a simple one-dimensional problem into two-dimensional one and design a scheme for valuation of Asian options, i.e. options with payoff depending on the average of prices collected over prespecified horizon. The algorithm is based on the approach combining the advantages of the finite element methods together with the piecewise polynomial generally discontinuous approximations. Finally, an illustrative example using DAX option market data is provided.

Hidden dynamics in models of discontinuity and switching

NASA Astrophysics Data System (ADS)

Jeffrey, Mike R.

2014-04-01

Sharp switches in behaviour, like impacts, stick-slip motion, or electrical relays, can be modelled by differential equations with discontinuities. A discontinuity approximates fine details of a switching process that lie beyond a bulk empirical model. The theory of piecewise-smooth dynamics describes what happens assuming we can solve the system of equations across its discontinuity. What this typically neglects is that effects which are vanishingly small outside the discontinuity can have an arbitrarily large effect at the discontinuity itself. Here we show that such behaviour can be incorporated within the standard theory through nonlinear terms, and these introduce multiple sliding modes. We show that the nonlinear terms persist in more precise models, for example when the discontinuity is smoothed out. The nonlinear sliding can be eliminated, however, if the model contains an irremovable level of unknown error, which provides a criterion for systems to obey the standard Filippov laws for sliding dynamics at a discontinuity.

Connection between self-stigma, adherence to treatment, and discontinuation of medication

PubMed Central

Kamaradova, Dana; Latalova, Klara; Prasko, Jan; Kubinek, Radim; Vrbova, Kristyna; Mainerova, Barbora; Cinculova, Andrea; Ociskova, Marie; Holubova, Michaela; Smoldasova, Jarmila; Tichackova, Anezka

2016-01-01

Introduction Self-stigma plays a role in many areas of the patient’s life. Furthermore, it also discourages therapy. The aim of our study was to examine associations between self-stigma and adherence to treatment and discontinuation of medication in patients from various diagnostic groups. Methods This cross-sectional study involved outpatients attending the Department of Psychiatry, University Hospital Olomouc, Czech Republic. The level of self-stigma was measured with the Internalized Stigma of Mental Illness and adherence with the Drug Attitude Inventory. The patients also anonymously filled out a demographic questionnaire which included a question asking whether they had discontinued their medication in the past. Results We examined data from 332 patients from six basic diagnostic categories (substance abuse disorders, schizophrenia, bipolar disorders, depressive disorders, anxiety disorders, and personality disorders). The study showed a statistically significant negative correlation between self-stigma and adherence to treatment in all diagnostic groups. Self-stigma correlated positively and adherence negatively with the severity of disorders. Another important factor affecting both variables was partnership. Self-stigma positively correlated with doses of antidepressants and adherence with doses of anxiolytics. Self-stigma also negatively correlated with education, and positively with a number of hospitalizations and number of psychiatrists visited. Adherence was further positively correlated with age and age of onset of disorders. Regression analysis showed that self-stigma was an important factor negatively influencing adherence to treatment and significantly contributing to voluntary discontinuation of drugs. The level of self-stigma did not differ between diagnostic categories. Patients suffering from schizophrenia had the lowest adherence to treatment. Conclusion The study showed a significant correlation between self-stigma and adherence to treatment

Excursions in fluvial (dis)continuity

NASA Astrophysics Data System (ADS)

Grant, Gordon E.; O'Connor, Jim; Safran, Elizabeth

2017-01-01

Lurking below the twin concepts of connectivity and disconnectivity are their first, and in some ways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in landscapes and rivers. We examine the historical roots of continuum and discontinuum thinking, and how much of our understanding of geomorphology rests on contrasting views of continuity and discontinuity. By continuum thinking we refer to a conception of geomorphic processes as well as geomorphic features that are expressed along continuous gradients without abrupt changes, transitions, or thresholds. Balance of forces, graded streams, and hydraulic geometry are all examples of this perspective. The continuum view has played a prominent role in diverse disciplinary fields, including ecology, paleontology, and evolutionary biology, in large part because it allows us to treat complex phenomena as orderly progressions and invoke or assume equilibrium processes that introduce order and prediction into our sciences. In contrast the discontinuous view is a distinct though complementary conceptual framework that incorporates non-uniform, non-progressive, and non-equilibrium thinking into understanding geomorphic processes and landscapes. We distinguish and discuss examples of three different ways in which discontinuous thinking can be expressed: 1) discontinuous spatial arrangements or singular events; 2) specific process domains generally associated with thresholds, either intrinsic or extrinsic; and 3) physical dynamics or changes in state, again often threshold-linked. In moving beyond the continuous perspective, a fertile set of ideas comes into focus: thresholds, non-equilibrium states, heterogeneity, catastrophe. The range of phenomena that is thereby opened up to scientific exploration similarly expands

Excursions in fluvial (dis)continuity

USGS Publications Warehouse

Grant, Gordon E.; O'Connor, James E.; Safran, Elizabeth

2017-01-01

Lurking below the twin concepts of connectivity and disconnectivity are their first, and in some ways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in landscapes and rivers. We examine the historical roots of continuum and discontinuum thinking, and how much of our understanding of geomorphology rests on contrasting views of continuity and discontinuity. By continuum thinking we refer to a conception of geomorphic processes as well as geomorphic features that are expressed along continuous gradients without abrupt changes, transitions, or thresholds. Balance of forces, graded streams, and hydraulic geometry are all examples of this perspective. The continuum view has played a prominent role in diverse disciplinary fields, including ecology, paleontology, and evolutionary biology, in large part because it allows us to treat complex phenomena as orderly progressions and invoke or assume equilibrium processes that introduce order and prediction into our sciences.In contrast the discontinuous view is a distinct though complementary conceptual framework that incorporates non-uniform, non-progressive, and non-equilibrium thinking into understanding geomorphic processes and landscapes. We distinguish and discuss examples of three different ways in which discontinuous thinking can be expressed: 1) discontinuous spatial arrangements or singular events; 2) specific process domains generally associated with thresholds, either intrinsic or extrinsic; and 3) physical dynamics or changes in state, again often threshold-linked. In moving beyond the continuous perspective, a fertile set of ideas comes into focus: thresholds, non-equilibrium states, heterogeneity, catastrophe. The range of phenomena that is thereby opened up to scientific exploration similarly expands

Hospital Factors Associated With Care Discontinuity Following Emergency General Surgery.

PubMed

Havens, Joaquim M; Olufajo, Olubode A; Tsai, Thomas C; Jiang, Wei; Columbus, Alexandra B; Nitzschke, Stephanie L; Cooper, Zara; Salim, Ali

2017-03-01

Although there is evidence that changes in clinicians during the continuum of care (care discontinuity) are associated with higher mortality and complications among surgical patients, little is known regarding the drivers of care discontinuity among emergency general surgery (EGS) patients. To identify hospital factors associated with care discontinuity among EGS patients. We performed a retrospective analysis of the 100% Medicare inpatient claims file, from January 1, 2008, to November 30, 2011, and matched patient details to hospital information in the 2011 American Hospital Association Annual Survey database. We selected patients aged 65 years and older who had the most common procedures associated with the previously defined American Association for the Surgery of Trauma EGS diagnosis categories and survived to hospital discharge across the United States. The current analysis was conducted from February 1, 2016, to March 24, 2016. Care discontinuity defined as readmission within 30 days to nonindex hospitals. There were 109 443 EGS patients readmitted within 30 days of discharge and 20 396 (18.6%) were readmitted to nonindex hospitals. Of the readmitted patients, 61 340 (56%) were female. Care discontinuity was higher among patients who were male (19.5% vs 18.0%), those younger than 85 years old (19.0% vs 16.6%), and those who lived 12.8 km (8 miles) or more away from the index hospitals (23.7% vs 14.8%) (all P < .001). Care discontinuity was independently associated with mortality (adjusted odds ratio [aOR], 1.16; 95% CI, 1.08-1.25). Hospital factors associated with care discontinuity included bed size of 200 or more (aOR, 1.45; 95% CI, 1.36-1.54), safety-net status (aOR, 1.35; 95% CI, 1.27-1.43), and teaching status (aOR, 1.18; 95% CI, 1.09-1.28). Care discontinuity was significantly lower among designated trauma centers (aOR, 0.89; 95% CI, 0.83-0.94) and highest among hospitals in the Midwest (aOR, 1.15; 95% CI, 1.05-1.26). Nearly 1 in 5 older EGS

Long-term outcome of patients with Crohn's disease who discontinued infliximab therapy upon clinical remission.

PubMed

Papamichael, Konstantinos; Vande Casteele, Niels; Gils, Ann; Tops, Sophie; Hauenstein, Scott; Singh, Sharat; Princen, Fred; Van Assche, Gert; Rutgeerts, Paul; Vermeire, Severine; Ferrante, Marc

2015-06-01

There are limited data on the effects of discontinuing infliximab therapy for Crohn's disease (CD). We investigated the long-term outcome of patients with CD who discontinued infliximab while in clinical remission, and searched for prognostic markers of continued remission after infliximab cessation. We performed a retrospective, single-center study of 100 patients with CD who discontinued infliximab upon achieving clinical remission; 84 patients continued immunomodulator therapy. Clinical and endoscopic data were retrieved from a medical database in Belgium, and patients were followed up through April 2013 (median, 9.7 y; interquartile range, 8-11.5 y). Sustained clinical remission (SCR) was defined as maintenance of disease remission, without escalation in medical therapy or CD-related surgeries, until the end of the follow-up period. We measured trough concentrations of infliximab, antibodies to microbial antigens, and circulating inflammatory markers in serum samples collected before treatment and at the time of infliximab discontinuation. At the end of the follow-up period, 52 patients had SCR. Univariate (log-rank) analysis associated SCR with patient age at diagnosis (≥25 y; P = .012) and disease duration (<1 y; P = .017). Among factors evaluated at the time of infliximab discontinuation, infliximab trough concentrations (<6 μg/mL; P = .031), complete mucosal healing (P = .046), and serum positivity for vascular cell adhesion molecule-1 (>0.67 μg/mL; P = .024) were associated with SCR. In multiple Cox proportional hazards regression analysis, only age at diagnosis of 25 years and older was associated independently with SCR (hazard ratio, 1.83; 95% confidence interval, 1.03-3.25; P = .04). In a large, real-life study, 52% of patients with CD who discontinued infliximab upon achieving clinical remission remained in SCR after a median period of approximately 10 years; Most patients remained on immunomodulator therapy. Although patients with CD have

A comparison of Cox and logistic regression for use in genome-wide association studies of cohort and case-cohort design.

PubMed

Staley, James R; Jones, Edmund; Kaptoge, Stephen; Butterworth, Adam S; Sweeting, Michael J; Wood, Angela M; Howson, Joanna M M

2017-06-01

Logistic regression is often used instead of Cox regression to analyse genome-wide association studies (GWAS) of single-nucleotide polymorphisms (SNPs) and disease outcomes with cohort and case-cohort designs, as it is less computationally expensive. Although Cox and logistic regression models have been compared previously in cohort studies, this work does not completely cover the GWAS setting nor extend to the case-cohort study design. Here, we evaluated Cox and logistic regression applied to cohort and case-cohort genetic association studies using simulated data and genetic data from the EPIC-CVD study. In the cohort setting, there was a modest improvement in power to detect SNP-disease associations using Cox regression compared with logistic regression, which increased as the disease incidence increased. In contrast, logistic regression had more power than (Prentice weighted) Cox regression in the case-cohort setting. Logistic regression yielded inflated effect estimates (assuming the hazard ratio is the underlying measure of association) for both study designs, especially for SNPs with greater effect on disease. Given logistic regression is substantially more computationally efficient than Cox regression in both settings, we propose a two-step approach to GWAS in cohort and case-cohort studies. First to analyse all SNPs with logistic regression to identify associated variants below a pre-defined P-value threshold, and second to fit Cox regression (appropriately weighted in case-cohort studies) to those identified SNPs to ensure accurate estimation of association with disease.

Delirium Associated With Fluoxetine Discontinuation: A Case Report.

PubMed

Fan, Kuang-Yuan; Liu, Hsing-Cheng

Withdrawal symptoms on selective serotonin reuptake inhibitor (SSRI) discontinuation have raised clinical attention increasingly. However, delirium is rarely reported in the SSRI discontinuation syndrome. We report a case of delirium developing after fluoxetine discontinuation in a 65-year-old female patient with major depressive disorder. She experienced psychotic depression with limited response to treatment of fluoxetine 40 mg/d and quetiapine 100 mg/d for 3 months. After admission, we tapered fluoxetine gradually in 5 days because of its limited effect. However, delirious pictures developed 2 days after we stopped fluoxetine. Three days later, we added back fluoxetine 10 mg/d. Her delirious features gradually improved, and the clinical presentation turned into previous psychotic depression state. We gradually increased the medication to fluoxetine 60 mg/d and olanzapine 20 mg/d in the following 3 weeks. Her psychotic symptoms decreased, and there has been no delirious picture noted thereafter. Delirium associated with fluoxetine discontinuation is a much rarer complication in SSRI discontinuation syndrome. The symptoms of SSRI discontinuation syndrome may be attributable to a rapid decrease in serotonin availability. In general, the shorter the half-life of any medication, the greater the likelihood patients will experience discontinuation symptoms. Genetic vulnerability might be a potential factor to explain that SSRI discontinuation syndrome also occurred rapidly in people taking long-half-life fluoxetine. The genetic polymorphisms of both pharmacokinetic and pharmacodynamic pathways might be potentially associated with SSRI discontinuation syndrome.

Sativex in resistant multiple sclerosis spasticity: Discontinuation study in a large population of Italian patients (SA.FE. study)

PubMed Central

Solaro, Claudio; Righini, Isabella; Bergamaschi, Roberto; Bonavita, Simona; Bossio, Roberto Bruno; Brescia Morra, Vincenzo; Costantino, Gianfranco; Cavalla, Paola; Centonze, Diego; Comi, Giancarlo; Cottone, Salvatore; Danni, Maura Chiara; Francia, Ada; Gajofatto, Alberto; Gasperini, Claudio; Zaffaroni, Mauro; Petrucci, Loredana; Signoriello, Elisabetta; Maniscalco, Giorgia Teresa; Spinicci, Gabriella; Matta, Manuela; Mirabella, Massimiliano; Pedà, Graziella; Castelli, Letizia; Rovaris, Marco; Sessa, Edoardo; Spitaleri, Daniele; Paolicelli, Damiano; Granata, Alfredo; Zappia, Mario

2017-01-01

Background The approval of Sativex for the management of multiple sclerosis (MS) spasticity opened a new opportunity to many patients. In Italy, the healthcare payer can be fully reimbursed by the involved pharma company with the cost of treatment for patients not responding after a 4 week (28 days) trial period (Payment by Results, PbR), and 50% reimbursed with the cost of 6 weeks (42 days) treatment for other patients discontinuing (Cost Sharing, CS). The aim of our study was to describe the Sativex discontinuation profile from a large population of spasticity treated Italian MS patients. Methods We collected data of patients from 30 MS centres across the country starting Sativex between January 2014 and February 2015. Data were collected from the mandatory Italian Medicines Agency (AIFA) web-registry. Predictors of treatment discontinuation were assessed using a multivariate Cox proportional regression analysis. Results During the observation period 631 out of 1597 (39.5%) patients discontinued Sativex. The Kaplan-Meier estimates curve showed that 333 patients (20.8%) discontinued treatment at 4 weeks while 422 patients (26.4%) discontinued at 6 weeks. We found after adjusted modeling that a higher NRS score at T1 (adjHR 2.23, 95% 2.07–2.41, p<0.001) and a lower baseline NRS score (adjHR 0.51 95% CI 0.46–0.56, p<0.001) were predictive of treatment discontinuation. Conclusion These data show that the first 6 weeks are useful in identifying those patients in which Sativex could be effective, thus avoiding the cost of longer term evaluation. PMID:28763462

Hybridized Multiscale Discontinuous Galerkin Methods for Multiphysics

DTIC Science & Technology

2015-09-14

discontinuous Galerkin method for the numerical solution of the Helmholtz equation , J. Comp. Phys., 290, 318–335, 2015. [14] N.C. NGUYEN, J. PERAIRE...approximations of the Helmholtz equation for a very wide range of wave frequencies. Our approach combines the hybridizable discontinuous Galerkin methodology...local approximation spaces of the hybridizable discontinuous Galerkin methods with precomputed phases which are solutions of the eikonal equation in

Outpatient CPOE orders discontinued due to 'erroneous entry': prospective survey of prescribers' explanations for errors.

PubMed

Hickman, Thu-Trang T; Quist, Arbor Jessica Lauren; Salazar, Alejandra; Amato, Mary G; Wright, Adam; Volk, Lynn A; Bates, David W; Schiff, Gordon

2018-04-01

Computerised prescriber order entry (CPOE) systems users often discontinue medications because the initial order was erroneous. To elucidate error types by querying prescribers about their reasons for discontinuing outpatient medication orders that they had self-identified as erroneous. During a nearly 3 year retrospective data collection period, we identified 57 972 drugs discontinued with the reason 'Error (erroneous entry)." Because chart reviews revealed limited information about these errors, we prospectively studied consecutive, discontinued erroneous orders by querying prescribers in near-real-time to learn more about the erroneous orders. From January 2014 to April 2014, we prospectively emailed prescribers about outpatient drug orders that they had discontinued due to erroneous initial order entry. Of 2 50 806 medication orders in these 4 months, 1133 (0.45%) of these were discontinued due to error. From these 1133, we emailed 542 unique prescribers to ask about their reason(s) for discontinuing these mediation orders in error. We received 312 responses (58% response rate). We categorised these responses using a previously published taxonomy. The top reasons for these discontinued erroneous orders included: medication ordered for wrong patient (27.8%, n=60); wrong drug ordered (18.5%, n=40); and duplicate order placed (14.4%, n=31). Other common discontinued erroneous orders related to drug dosage and formulation (eg, extended release versus not). Oxycodone (3%) was the most frequent drug discontinued error. Drugs are not infrequently discontinued 'in error.' Wrong patient and wrong drug errors constitute the leading types of erroneous prescriptions recognised and discontinued by prescribers. Data regarding erroneous medication entries represent an important source of intelligence about how CPOE systems are functioning and malfunctioning, providing important insights regarding areas for designing CPOE more safely in the future. © Article author

38 CFR 21.4135 - Discontinuance dates.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) VOCATIONAL REHABILITATION AND EDUCATION Administration of Educational Assistance Programs Payments; Educational Assistance Allowance § 21.4135 Discontinuance dates. The effective date of reduction or discontinuance of educational assistance allowance will be as specified in this section. If more than one type of...

38 CFR 21.4135 - Discontinuance dates.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) VOCATIONAL REHABILITATION AND EDUCATION Administration of Educational Assistance Programs Payments; Educational Assistance Allowance § 21.4135 Discontinuance dates. The effective date of reduction or discontinuance of educational assistance allowance will be as specified in this section. If more than one type of...

Variational models for discontinuity detection

NASA Astrophysics Data System (ADS)

Vitti, Alfonso; Battista Benciolini, G.

2010-05-01

The Mumford-Shah variational model produces a smooth approximation of the data and detects data discontinuities by solving a minimum problem involving an energy functional. The Blake-Zisserman model permits also the detection of discontinuities in the first derivative of the approximation. This model can result in a quasi piece-wise linear approximation, whereas the Mumford-Shah can result in a quasi piece-wise constant approximation. The two models are well known in the mathematical literature and are widely adopted in computer vision for image segmentation. In Geodesy the Blake-Zisserman model has been applied successfully to the detection of cycle-slips in linear combinations of GPS measurements. Few attempts to apply the model to time series of coordinates have been done so far. The problem of detecting discontinuities in time series of GNSS coordinates is well know and its relevance increases as the quality of geodetic measurements, analysis techniques, models and products improves. The application of the Blake-Zisserman model appears reasonable and promising due to the model characteristic to detect both position and velocity discontinuities in the same time series. The detection of position and velocity changes is of great interest in geophysics where the discontinuity itself can be the very relevant object. In the work for the realization of reference frames, detecting position and velocity discontinuities may help to define models that can handle non-linear motions. In this work the Mumford-Shah and the Blake-Zisserman models are briefly presented, the treatment is carried out from a practical viewpoint rather than from a theoretical one. A set of time series of GNSS coordinates has been processed and the results are presented in order to highlight the capabilities and the weakness of the variational approach. A first attempt to derive some indication for the automatic set up of the model parameters has been done. The underlying relation that could links

Calibration Designs for Non-Monolithic Wind Tunnel Force Balances

NASA Technical Reports Server (NTRS)

Johnson, Thomas H.; Parker, Peter A.; Landman, Drew

2010-01-01

This research paper investigates current experimental designs and regression models for calibrating internal wind tunnel force balances of non-monolithic design. Such calibration methods are necessary for this class of balance because it has an electrical response that is dependent upon the sign of the applied forces and moments. This dependency gives rise to discontinuities in the response surfaces that are not easily modeled using traditional response surface methodologies. An analysis of current recommended calibration models is shown to lead to correlated response model terms. Alternative modeling methods are explored which feature orthogonal or near-orthogonal terms.

Demographic responses of Pinguicula ionantha to prescribed fire: a regression-design LTRE approach.

PubMed

Kesler, Herbert C; Trusty, Jennifer L; Hermann, Sharon M; Guyer, Craig

2008-06-01

This study describes the use of periodic matrix analysis and regression-design life table response experiments (LTRE) to investigate the effects of prescribed fire on demographic responses of Pinguicula ionantha, a federally listed plant endemic to the herb bog/savanna community in north Florida. Multi-state mark-recapture models with dead recoveries were used to estimate survival and transition probabilities for over 2,300 individuals in 12 populations of P. ionantha. These estimates were applied to parameterize matrix models used in further analyses. P. ionantha demographics were found to be strongly dependent on prescribed fire events. Periodic matrix models were used to evaluate season of burn (either growing or dormant season) for fire return intervals ranging from 1 to 20 years. Annual growing and biannual dormant season fires maximized population growth rates for this species. A regression design LTRE was used to evaluate the effect of number of days since last fire on population growth. Maximum population growth rates calculated using standard asymptotic analysis were realized shortly following a burn event (<2 years), and a regression design LTRE showed that short-term fire-mediated changes in vital rates translated into observed increases in population growth. The LTRE identified fecundity and individual growth as contributing most to increases in post-fire population growth. Our analyses found that the current four-year prescribed fire return intervals used at the study sites can be significantly shortened to increase the population growth rates of this rare species. Understanding the role of fire frequency and season in creating and maintaining appropriate habitat for this species may aid in the conservation of this and other rare herb bog/savanna inhabitants.

38 CFR 21.9635 - Discontinuance dates.

Code of Federal Regulations, 2013 CFR

2013-07-01

... effective the last date of attendance; and (ii) Independent study or distance learning effective on the... learning, VA will terminate educational assistance effective the date the last lesson was serviced... Discontinuance dates. The effective date of a reduction or discontinuance of educational assistance will be as...

An investigation of the speeding-related crash designation through crash narrative reviews sampled via logistic regression.

PubMed

Fitzpatrick, Cole D; Rakasi, Saritha; Knodler, Michael A

2017-01-01

Speed is one of the most important factors in traffic safety as higher speeds are linked to increased crash risk and higher injury severities. Nearly a third of fatal crashes in the United States are designated as "speeding-related", which is defined as either "the driver behavior of exceeding the posted speed limit or driving too fast for conditions." While many studies have utilized the speeding-related designation in safety analyses, no studies have examined the underlying accuracy of this designation. Herein, we investigate the speeding-related crash designation through the development of a series of logistic regression models that were derived from the established speeding-related crash typologies and validated using a blind review, by multiple researchers, of 604 crash narratives. The developed logistic regression model accurately identified crashes which were not originally designated as speeding-related but had crash narratives that suggested speeding as a causative factor. Only 53.4% of crashes designated as speeding-related contained narratives which described speeding as a causative factor. Further investigation of these crashes revealed that the driver contributing code (DCC) of "driving too fast for conditions" was being used in three separate situations. Additionally, this DCC was also incorrectly used when "exceeding the posted speed limit" would likely have been a more appropriate designation. Finally, it was determined that the responding officer only utilized one DCC in 82% of crashes not designated as speeding-related but contained a narrative indicating speed as a contributing causal factor. The use of logistic regression models based upon speeding-related crash typologies offers a promising method by which all possible speeding-related crashes could be identified. Published by Elsevier Ltd.

Clinician support and psychosocial risk factors associated with breastfeeding discontinuation.

PubMed

Taveras, Elsie M; Capra, Angela M; Braveman, Paula A; Jensvold, Nancy G; Escobar, Gabriel J; Lieu, Tracy A

2003-07-01

Breastfeeding rates fall short of goals set in Healthy People 2010 and other national recommendations. The current, national breastfeeding continuation rate of 29% at 6 months lags behind the Healthy People 2010 goal of 50%. The objective of this study was to evaluate associations between breastfeeding discontinuation at 2 and 12 weeks postpartum and clinician support, maternal physical and mental health status, workplace issues, and other factors amenable to intervention. A prospective cohort study was conducted of low-risk mothers and infants who were in a health maintenance organization and enrolled in a randomized, controlled trial of home visits. Mothers were interviewed in person at 1 to 2 days postpartum and by telephone at 2 and 12 weeks. Logistic regression modeling was performed to assess the independent effects of the predictors of interest, adjusting for sociodemographic and other confounding variables. Of the 1163 mother-newborn pairs in the cohort, 1007 (87%) initiated breastfeeding, 872 (75%) were breastfeeding at the 2-week interview, and 646 (55%) were breastfeeding at the 12-week interview. In the final multivariate models, breastfeeding discontinuation at 2 weeks was associated with lack of confidence in ability to breastfeed at the 1- to 2-day interview (odds ratio [OR]: 2.8; 95% confidence interval [CI]: 1.02-7.6), early breastfeeding problems (OR: 1.5; 95% CI: 1.1-1.97), Asian race/ethnicity (OR: 2.6; 95% CI: 1.1-5.7), and lower maternal education (OR: 1.5; 95% CI: 1.2-1.9). Mothers were much less likely to discontinue breastfeeding at 12 weeks postpartum if they reported (during the 12-week interview) having received encouragement from their clinician to breastfeed (OR: 0.6; 95% CI: 0.4-0.8). Breastfeeding discontinuation at 12 weeks was also associated with demographic factors and maternal depressive symptoms (OR: 1.18; 95% CI: 1.01-1.37) and returning to work or school by 12 weeks postpartum (OR: 2.4; 95% CI: 1.8-3.3). Our results indicate

27 CFR 11.38 - Discontinued products.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Discontinued products. 11.38 Section 11.38 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... products. When a producer or importer discontinues the production or importation of a product, a trade...

Using EHR Data to Detect Prescribing Errors in Rapidly Discontinued Medication Orders.

PubMed

Burlison, Jonathan D; McDaniel, Robert B; Baker, Donald K; Hasan, Murad; Robertson, Jennifer J; Howard, Scott C; Hoffman, James M

2018-01-01

Previous research developed a new method for locating prescribing errors in rapidly discontinued electronic medication orders. Although effective, the prospective design of that research hinders its feasibility for regular use. Our objectives were to assess a method to retrospectively detect prescribing errors, to characterize the identified errors, and to identify potential improvement opportunities. Electronically submitted medication orders from 28 randomly selected days that were discontinued within 120 minutes of submission were reviewed and categorized as most likely errors, nonerrors, or not enough information to determine status. Identified errors were evaluated by amount of time elapsed from original submission to discontinuation, error type, staff position, and potential clinical significance. Pearson's chi-square test was used to compare rates of errors across prescriber types. In all, 147 errors were identified in 305 medication orders. The method was most effective for orders that were discontinued within 90 minutes. Duplicate orders were most common; physicians in training had the highest error rate ( p  < 0.001), and 24 errors were potentially clinically significant. None of the errors were voluntarily reported. It is possible to identify prescribing errors in rapidly discontinued medication orders by using retrospective methods that do not require interrupting prescribers to discuss order details. Future research could validate our methods in different clinical settings. Regular use of this measure could help determine the causes of prescribing errors, track performance, and identify and evaluate interventions to improve prescribing systems and processes. Schattauer GmbH Stuttgart.

Trapped particles at a magnetic discontinuity

NASA Technical Reports Server (NTRS)

Stern, D. P.

1972-01-01

At a tangential discontinuity between two constant magnetic fields a layer of trapped particles can exist, this work examines the conditions under which the current carried by such particles tends to maintain the discontinuity. Three cases are examined. If the discontinuity separates aligned vacuum fields, the only requirement is that they be antiparallel. With arbitrary relative orientations, the field must have equal intensities on both sides. Finally, with a guiding center plasma on both sides, the condition reduces to a relation which is also derivable from hydromagnetic theory. Arguments are presented for the occurrence of such trapped modes in the magnetopause and for the non-existence of specular particle reflection.

Active Correction of Aperture Discontinuities-Optimized Stroke Minimization. I. A New Adaptive Interaction Matrix Algorithm

NASA Astrophysics Data System (ADS)

Mazoyer, J.; Pueyo, L.; N'Diaye, M.; Fogarty, K.; Zimmerman, N.; Leboulleux, L.; St. Laurent, K. E.; Soummer, R.; Shaklan, S.; Norman, C.

2018-01-01

Future searches for bio-markers on habitable exoplanets will rely on telescope instruments that achieve extremely high contrast at small planet-to-star angular separations. Coronagraphy is a promising starlight suppression technique, providing excellent contrast and throughput for off-axis sources on clear apertures. However, the complexity of space- and ground-based telescope apertures goes on increasing over time, owing to the combination of primary mirror segmentation, the secondary mirror, and its support structures. These discontinuities in the telescope aperture limit the coronagraph performance. In this paper, we present ACAD-OSM, a novel active method to correct for the diffractive effects of aperture discontinuities in the final image plane of a coronagraph. Active methods use one or several deformable mirrors that are controlled with an interaction matrix to correct for the aberrations in the pupil. However, they are often limited by the amount of aberrations introduced by aperture discontinuities. This algorithm relies on the recalibration of the interaction matrix during the correction process to overcome this limitation. We first describe the ACAD-OSM technique and compare it to the previous active methods for the correction of aperture discontinuities. We then show its performance in terms of contrast and off-axis throughput for static aperture discontinuities (segmentation, struts) and for some aberrations evolving over the life of the instrument (residual phase aberrations, artifacts in the aperture, misalignments in the coronagraph design). This technique can now obtain the Earth-like planet detection threshold of {10}10 contrast on any given aperture over at least a 10% spectral bandwidth, with several coronagraph designs.

A Reconstructed Discontinuous Galerkin Method for the Euler Equations on Arbitrary Grids

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

Hong Luo; Luqing Luo; Robert Nourgaliev

2012-11-01

A reconstruction-based discontinuous Galerkin (RDG(P1P2)) method, a variant of P1P2 method, is presented for the solution of the compressible Euler equations on arbitrary grids. In this method, an in-cell reconstruction, designed to enhance the accuracy of the discontinuous Galerkin method, is used to obtain a quadratic polynomial solution (P2) from the underlying linear polynomial (P1) discontinuous Galerkin solution using a least-squares method. The stencils used in the reconstruction involve only the von Neumann neighborhood (face-neighboring cells) and are compact and consistent with the underlying DG method. The developed RDG method is used to compute a variety of flow problems onmore » arbitrary meshes to demonstrate its accuracy, efficiency, robustness, and versatility. The numerical results indicate that this RDG(P1P2) method is third-order accurate, and outperforms the third-order DG method (DG(P2)) in terms of both computing costs and storage requirements.« less

27 CFR 25.277 - Discontinuance of operations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Pilot Brewing Plants § 25.277 Discontinuance of operations. When operations of a pilot brewing plant are to be discontinued, the operator shall notify the...

27 CFR 25.277 - Discontinuance of operations.

Code of Federal Regulations, 2011 CFR

2011-04-01

... BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Pilot Brewing Plants § 25.277 Discontinuance of operations. When operations of a pilot brewing plant are to be discontinued, the operator shall notify the...

Risk of relapse after antidepressant discontinuation in anxiety disorders, obsessive-compulsive disorder, and post-traumatic stress disorder: systematic review and meta-analysis of relapse prevention trials.

PubMed

Batelaan, Neeltje M; Bosman, Renske C; Muntingh, Anna; Scholten, Willemijn D; Huijbregts, Klaas M; van Balkom, Anton J L M

2017-09-13

Objectives  To examine the risk of relapse and time to relapse after discontinuation of antidepressants in patients with anxiety disorder who responded to antidepressants, and to explore whether relapse risk is related to type of anxiety disorder, type of antidepressant, mode of discontinuation, duration of treatment and follow-up, comorbidity, and allowance of psychotherapy. Design  Systematic review and meta-analyses of relapse prevention trials. Data sources  PubMed, Cochrane, Embase, and clinical trial registers (from inception to July 2016). Study selection  Eligible studies included patients with anxiety disorder who responded to antidepressants, randomised patients double blind to either continuing antidepressants or switching to placebo, and compared relapse rates or time to relapse. Data extraction  Two independent raters selected studies and extracted data. Random effect models were used to estimate odds ratios for relapse, hazard ratios for time to relapse, and relapse prevalence per group. The effect of various categorical and continuous variables was explored with subgroup analyses and meta-regression analyses respectively. Bias was assessed using the Cochrane tool. Results  The meta-analysis included 28 studies (n=5233) examining relapse with a maximum follow-up of one year. Across studies, risk of bias was considered low. Discontinuation increased the odds of relapse compared with continuing antidepressants (summary odds ratio 3.11, 95% confidence interval 2.48 to 3.89). Subgroup analyses and meta-regression analyses showed no statistical significance. Time to relapse (n=3002) was shorter when antidepressants were discontinued (summary hazard ratio 3.63, 2.58 to 5.10; n=11 studies). Summary relapse prevalences were 36.4% (30.8% to 42.1%; n=28 studies) for the placebo group and 16.4% (12.6% to 20.1%; n=28 studies) for the antidepressant group, but prevalence varied considerably across studies, most likely owing to differences in the length of

38 CFR 21.7635 - Discontinuance dates.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-Educational Assistance § 21.7635 Discontinuance dates. The effective date of reduction or discontinuance of... mitigating circumstances VA will terminate or reduce educational assistance effective the first date of the... practices of the institution of higher learning. (Authority: 10 U.S.C. 16136(b), 38 U.S.C. 3680(a); Pub. L...

38 CFR 21.7635 - Discontinuance dates.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-Educational Assistance § 21.7635 Discontinuance dates. The effective date of reduction or discontinuance of... mitigating circumstances VA will terminate or reduce educational assistance effective the first date of the... practices of the institution of higher learning. (Authority: 10 U.S.C. 16136(b), 38 U.S.C. 3680(a); Pub. L...

38 CFR 21.7635 - Discontinuance dates.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-Educational Assistance § 21.7635 Discontinuance dates. The effective date of reduction or discontinuance of... mitigating circumstances VA will terminate or reduce educational assistance effective the first date of the... practices of the institution of higher learning. (Authority: 10 U.S.C. 16136(b), 38 U.S.C. 3680(a); Pub. L...

38 CFR 21.7635 - Discontinuance dates.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-Educational Assistance § 21.7635 Discontinuance dates. The effective date of reduction or discontinuance of... mitigating circumstances VA will terminate or reduce educational assistance effective the first date of the... practices of the institution of higher learning. (Authority: 10 U.S.C. 16136(b), 38 U.S.C. 3680(a); Pub. L...

38 CFR 21.7635 - Discontinuance dates.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-Educational Assistance § 21.7635 Discontinuance dates. The effective date of reduction or discontinuance of... mitigating circumstances VA will terminate or reduce educational assistance effective the first date of the... practices of the institution of higher learning. (Authority: 10 U.S.C. 16136(b), 38 U.S.C. 3680(a); Pub. L...

Biomarkers From Late Pregnancy to 6 Weeks Postpartum in HIV-Infected Women Who Continue Versus Discontinue Antiretroviral Therapy After Delivery

PubMed Central

Hoffman, Risa M.; Leister, Erin; Kacanek, Deborah; Shapiro, David E.; Read, Jennifer S.; Bryson, Yvonne; Currier, Judith S.

2013-01-01

Background Women who use antiretroviral therapy (ART) solely for the prevention of mother-to-child transmission of HIV discontinue postpartum. We hypothesized that women discontinuing ART by 6 weeks postpartum (“discontinuers”) would have elevated postpartum inflammatory biomarker levels relative to women remaining on ART postpartum (“continuers”). Methods Data from HIV-infected pregnant women enrolled in the International Maternal Pediatric Adolescent AIDS Clinical Trials Group P1025 with CD4 counts >350 cells per cubic millimeter before initiating ART or first pregnancy CD4 counts >400 cells per cubic millimeter after starting ART and with available stored plasma samples at >20 weeks of gestation, delivery, and 6 weeks postpartum were analyzed. Plasma samples were tested for highly sensitive C-reactive protein, D-dimer, and interleukin-6. We used longitudinal linear spline regression to model biomarkers over time. Results Data from 128 women (65 continuers and 63 discontinuers) were analyzed. All biomarkers increased from late pregnancy to delivery, then decreased postpartum (slopes different from 0, P < 0.001). Continuers had a steeper decrease in log D-dimer between delivery and 6 weeks postpartum than discontinuers (P = 0.002). Conclusions In contrast to results from treatment interruption studies in adults, both ART continuers and ART discontinuers had significant decreases in the levels of D-dimer, highly sensitive C-reactive protein, or interleukin-6 postpartum. Continuation was associated with a more rapid decline in D-dimer levels compared with discontinuation. PMID:23714738

Twelve-month discontinuation rates of levonorgestrel intrauterine system 13.5 mg and subdermal etonogestrel implant in women aged 18-44: A retrospective claims database analysis.

PubMed

Law, Amy; Liao, Laura; Lin, Jay; Yaldo, Avin; Lynen, Richard

2018-04-21

To investigate the 12-month discontinuation rates of levonorgestrel intrauterine system 13.5 mg (LNG-IUS 13.5) and subdermal etonogestrel (ENG) implant in the US. We identified women aged 18-44 who had an insertion of LNG-IUS 13.5 or ENG implant from the MarketScan Commercial claims database (7/1/2013-9/30/2014). Women were required to have 12 months of continuous insurance coverage prior to the insertion (baseline) and at least 12-months after (follow-up). Discontinuation was defined as presence of an insurance claim for pregnancy-related services, hysterectomy, female sterilization, a claim for another contraceptive method, or removal of the index contraceptive without re-insertion within 30 days. Using Cox regression we examined the potential impact of ENG implant vs. LNG-IUS 13.5 on the likelihood for discontinuation after controlling for patient characteristics. A total of 3680 (mean age: 25.4 years) LNG-IUS 13.5 and 23,770 (mean age: 24.6 years) ENG implant users met the selection criteria. Prior to insertion, 56.6% of LNG-IUS 13.5 and 42.1% of ENG implant users had used contraceptives, with oral contraceptives being most common (LNG-IUS 13.5: 42.1%; ENG implant: 28.5%). Among users of LNG-IUS 13.5 and ENG implant, rates of discontinuation were similar during the 12-month follow-up (LNG-IUS 13.5: 24.9%; ENG implant: 24.0%). Regression results showed that women using LNG-IUS 13.5 vs. ENG implant had similar likelihood for discontinuation (hazard ratio: 0.97, 95% confidence interval: 0.90-1.05, p=.41). In the real-world US setting, women aged 18-44 using LNG-IUS 13.5 and ENG implant have similar discontinuation rates after 12 months. In the United States, women aged 18-44 using levonorgestrel intrauterine system (13.5 mg) and subdermal etonogestrel implant have similar discontinuation rates after 12 months. Copyright © 2018 Elsevier Inc. All rights reserved.

Hierarchical Matching and Regression with Application to Photometric Redshift Estimation

NASA Astrophysics Data System (ADS)

Murtagh, Fionn

2017-06-01

This work emphasizes that heterogeneity, diversity, discontinuity, and discreteness in data is to be exploited in classification and regression problems. A global a priori model may not be desirable. For data analytics in cosmology, this is motivated by the variety of cosmological objects such as elliptical, spiral, active, and merging galaxies at a wide range of redshifts. Our aim is matching and similarity-based analytics that takes account of discrete relationships in the data. The information structure of the data is represented by a hierarchy or tree where the branch structure, rather than just the proximity, is important. The representation is related to p-adic number theory. The clustering or binning of the data values, related to the precision of the measurements, has a central role in this methodology. If used for regression, our approach is a method of cluster-wise regression, generalizing nearest neighbour regression. Both to exemplify this analytics approach, and to demonstrate computational benefits, we address the well-known photometric redshift or `photo-z' problem, seeking to match Sloan Digital Sky Survey (SDSS) spectroscopic and photometric redshifts.

Distributed collaborative probabilistic design for turbine blade-tip radial running clearance using support vector machine of regression

NASA Astrophysics Data System (ADS)

Fei, Cheng-Wei; Bai, Guang-Chen

2014-12-01

To improve the computational precision and efficiency of probabilistic design for mechanical dynamic assembly like the blade-tip radial running clearance (BTRRC) of gas turbine, a distribution collaborative probabilistic design method-based support vector machine of regression (SR)(called as DCSRM) is proposed by integrating distribution collaborative response surface method and support vector machine regression model. The mathematical model of DCSRM is established and the probabilistic design idea of DCSRM is introduced. The dynamic assembly probabilistic design of aeroengine high-pressure turbine (HPT) BTRRC is accomplished to verify the proposed DCSRM. The analysis results reveal that the optimal static blade-tip clearance of HPT is gained for designing BTRRC, and improving the performance and reliability of aeroengine. The comparison of methods shows that the DCSRM has high computational accuracy and high computational efficiency in BTRRC probabilistic analysis. The present research offers an effective way for the reliability design of mechanical dynamic assembly and enriches mechanical reliability theory and method.

Strategies for discontinuation of proton pump inhibitors: a systematic review.

PubMed

Haastrup, Peter; Paulsen, Maja S; Begtrup, Luise M; Hansen, Jane M; Jarbøl, Dorte E

2014-12-01

Proton pump inhibitors (PPIs) are considered to be overprescribed. Consensus on how to attempt discontinuation is, however, lacking. We therefore conducted a systematic review of clinical studies on discontinuation of PPIs. Systematic review based on clinical studies investigating discontinuation strategies and discontinuation rates for users of antisecretory medication judged eligible for withdrawal. The databases Medline, Embase and Cochrane Library were searched to December 2013 using the terms antisecretory, anti-ulcer, PPI, acid suppressant, discontinuation, step-down, step down, cessation, tapering, withdrawal and withhold. Search terms were used either singularly or in combination. Papers written in English or Scandinavian were included. Concurrent hand searching was undertaken to pursue references of references. The website ClinicalTrials.gov was searched for unpublished results and ongoing studies. A total of 371 abstracts were scrutinized to determine relevancy. The thorough search resulted in six clinical studies on strategies for discontinuation of PPIs. All discontinuation regimens used in the studies differed, and several interventions have been tested in order to decrease use of PPIs. Discontinuations were reported across all studies ranging from 14% to 64% without deteriorating symptom control. Tapering seems to be a more effective discontinuation strategy than abrupt discontinuation. Discontinuation of PPIs is feasible in a clinical setting, and a substantial number of the patients treated without a clear indication can safely reduce or discontinue treatment. Tapering seems to be the most effective way of doing this. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cascade Optimization Strategy with Neural Network and Regression Approximations Demonstrated on a Preliminary Aircraft Engine Design

NASA Technical Reports Server (NTRS)

Hopkins, Dale A.; Patnaik, Surya N.

2000-01-01

A preliminary aircraft engine design methodology is being developed that utilizes a cascade optimization strategy together with neural network and regression approximation methods. The cascade strategy employs different optimization algorithms in a specified sequence. The neural network and regression methods are used to approximate solutions obtained from the NASA Engine Performance Program (NEPP), which implements engine thermodynamic cycle and performance analysis models. The new methodology is proving to be more robust and computationally efficient than the conventional optimization approach of using a single optimization algorithm with direct reanalysis. The methodology has been demonstrated on a preliminary design problem for a novel subsonic turbofan engine concept that incorporates a wave rotor as a cycle-topping device. Computations of maximum thrust were obtained for a specific design point in the engine mission profile. The results (depicted in the figure) show a significant improvement in the maximum thrust obtained using the new methodology in comparison to benchmark solutions obtained using NEPP in a manual design mode.

Neural network and multiple linear regression to predict school children dimensions for ergonomic school furniture design.

PubMed

Agha, Salah R; Alnahhal, Mohammed J

2012-11-01

The current study investigates the possibility of obtaining the anthropometric dimensions, critical to school furniture design, without measuring all of them. The study first selects some anthropometric dimensions that are easy to measure. Two methods are then used to check if these easy-to-measure dimensions can predict the dimensions critical to the furniture design. These methods are multiple linear regression and neural networks. Each dimension that is deemed necessary to ergonomically design school furniture is expressed as a function of some other measured anthropometric dimensions. Results show that out of the five dimensions needed for chair design, four can be related to other dimensions that can be measured while children are standing. Therefore, the method suggested here would definitely save time and effort and avoid the difficulty of dealing with students while measuring these dimensions. In general, it was found that neural networks perform better than multiple linear regression in the current study. Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.

A Fourier spectral-discontinuous Galerkin method for time-dependent 3-D Schrödinger-Poisson equations with discontinuous potentials

NASA Astrophysics Data System (ADS)

Lu, Tiao; Cai, Wei

2008-10-01

In this paper, we propose a high order Fourier spectral-discontinuous Galerkin method for time-dependent Schrödinger-Poisson equations in 3-D spaces. The Fourier spectral Galerkin method is used for the two periodic transverse directions and a high order discontinuous Galerkin method for the longitudinal propagation direction. Such a combination results in a diagonal form for the differential operators along the transverse directions and a flexible method to handle the discontinuous potentials present in quantum heterojunction and supperlattice structures. As the derivative matrices are required for various time integration schemes such as the exponential time differencing and Crank Nicholson methods, explicit derivative matrices of the discontinuous Galerkin method of various orders are derived. Numerical results, using the proposed method with various time integration schemes, are provided to validate the method.

39 CFR 241.3 - Discontinuance of USPS-operated retail facilities.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 39 Postal Service 1 2013-07-01 2013-07-01 false Discontinuance of USPS-operated retail facilities... ESTABLISHMENT CLASSIFICATION, AND DISCONTINUANCE § 241.3 Discontinuance of USPS-operated retail facilities. (a... of whether an existing retail Post Office, station, or branch should be discontinued. The rules cover...

39 CFR 241.3 - Discontinuance of USPS-operated retail facilities.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 39 Postal Service 1 2014-07-01 2014-07-01 false Discontinuance of USPS-operated retail facilities... ESTABLISHMENT CLASSIFICATION, AND DISCONTINUANCE § 241.3 Discontinuance of USPS-operated retail facilities. (a... of whether an existing retail Post Office, station, or branch should be discontinued. The rules cover...

39 CFR 241.3 - Discontinuance of USPS-operated retail facilities.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 39 Postal Service 1 2012-07-01 2012-07-01 false Discontinuance of USPS-operated retail facilities... ESTABLISHMENT CLASSIFICATION, AND DISCONTINUANCE § 241.3 Discontinuance of USPS-operated retail facilities. (a... of whether an existing retail Post Office, station, or branch should be discontinued. The rules cover...

Program Discontinuance: A Faculty Perspective Revisited. Adopted Fall 2012

ERIC Educational Resources Information Center

Academic Senate for California Community Colleges, 2012

2012-01-01

The 1998 Academic Senate for California Community Colleges paper Program Discontinuance: A Faculty Perspective presented issues of program discontinuance and addressed principles and key factors for effective faculty participation in the development of fair and equitable program discontinuance processes. In 2009, an Academic Senate resolution…

O(t-α)-synchronization and Mittag-Leffler synchronization for the fractional-order memristive neural networks with delays and discontinuous neuron activations.

PubMed

Chen, Jiejie; Chen, Boshan; Zeng, Zhigang

2018-04-01

This paper investigates O(t -α )-synchronization and adaptive Mittag-Leffler synchronization for the fractional-order memristive neural networks with delays and discontinuous neuron activations. Firstly, based on the framework of Filippov solution and differential inclusion theory, using a Razumikhin-type method, some sufficient conditions ensuring the global O(t -α )-synchronization of considered networks are established via a linear-type discontinuous control. Next, a new fractional differential inequality is established and two new discontinuous adaptive controller is designed to achieve Mittag-Leffler synchronization between the drive system and the response systems using this inequality. Finally, two numerical simulations are given to show the effectiveness of the theoretical results. Our approach and theoretical results have a leading significance in the design of synchronized fractional-order memristive neural networks circuits involving discontinuous activations and time-varying delays. Copyright © 2018 Elsevier Ltd. All rights reserved.

Search for seismic discontinuities in the lower mantle

NASA Astrophysics Data System (ADS)

Vinnik, Lev; Kato, Mamoru; Kawakatsu, Hitoshi

2001-09-01

Indications of lower mantle discontinuities have been debated for decades, but still little is known about their properties, and their origins are enigmatic. In our study broad-band recordings of deep events are examined for the presence of signals from the lower-mantle discontinuities with a novel technique. We deconvolve vertical component of the P-wave coda in the period range around 10s by the S waveform and stack many deconvolved traces with moveout time corrections. In synthetic seismograms for an earth model without lower mantle discontinuities, the strongest signal thus detected in the time window of interest is often s`410'P phase (generated as S and reflected as P from the `410km' discontinuity above the source). In actual seismograms there are other phases that can be interpreted as converted from S to P at discontinuities in the lower mantle beneath the seismic source. We summarize the results of processing the seismograms (1) of deep events in Sunda arc at seismograph stations in east Asia, (2) deep Kermadec-Fiji-Tonga events at the J-array and FREESIA networks in Japan and stations in east Asia, and (3) deep events in the northwest Pacific region (Mariana, Izu-Bonin and the Japan arc) recorded at stations in north America. In our data there are indications of discontinuities near 860-880, 1010-1120, 1170-1250 and 1670-1800km depths. The clearest signals are obtained from the discontinuity at a depth of 1200km. We argue that the `900', `1200' and `1700km' discontinuities are global, but laterally variable in both depth and strength. Seismic stratification of the lower mantle may have bearings on the patterns of subduction, as revealed by tomographic models.

Influence of pacer continuity on continuous and discontinuous visuo-motor synchronisation.

PubMed

Zelic, Gregory; Varlet, Manuel; Kim, Jeesun; Davis, Chris

2016-09-01

Previous research has reported that synchronising movements with an external pacer, known as sensorimotor synchronisation (SMS), is more stable when the movements are discrete/discontinuous rather than continuous. A standard explanation considers that more efficient mechanisms are involved for regulating synchronisation when producing discontinuous movements. To date, however, only discontinuous pacers (e.g., metronomes) have been investigated to compare discontinuous and continuous SMS. We propose an alternative explanation whereby the discontinuous SMS has benefited from the matching between the (dis)continuous nature of the pacer and the (dis)continuous nature of the movements of synchronisation. The present experiment tested this explanation by examining the relative stability of discontinuous and continuous SMS when synchronising with a continuous pacer. Twelve participants finger tapped (discontinuous SMS) or continuously oscillated their forearm (continuous SMS) in synchrony with an oscillatory visual target. The continuity of the pacer was manipulated by varying the kinematic (harmonic to Rayleigh-like oscillations) and the frequency (0.5 and 1Hz) of the target oscillations. Overall, the results showed a more stable continuous than discontinuous SMS. Furthermore, the stability of the discontinuous SMS improved when increasing the discontinuity of the target displacements (high nonlinear kinematic and low frequency), showing an interaction between movement type and pacer continuity in SMS. Copyright © 2016 Elsevier B.V. All rights reserved.

An entropy stable nodal discontinuous Galerkin method for the two dimensional shallow water equations on unstructured curvilinear meshes with discontinuous bathymetry

NASA Astrophysics Data System (ADS)

Wintermeyer, Niklas; Winters, Andrew R.; Gassner, Gregor J.; Kopriva, David A.

2017-07-01

We design an arbitrary high-order accurate nodal discontinuous Galerkin spectral element approximation for the non-linear two dimensional shallow water equations with non-constant, possibly discontinuous, bathymetry on unstructured, possibly curved, quadrilateral meshes. The scheme is derived from an equivalent flux differencing formulation of the split form of the equations. We prove that this discretization exactly preserves the local mass and momentum. Furthermore, combined with a special numerical interface flux function, the method exactly preserves the mathematical entropy, which is the total energy for the shallow water equations. By adding a specific form of interface dissipation to the baseline entropy conserving scheme we create a provably entropy stable scheme. That is, the numerical scheme discretely satisfies the second law of thermodynamics. Finally, with a particular discretization of the bathymetry source term we prove that the numerical approximation is well-balanced. We provide numerical examples that verify the theoretical findings and furthermore provide an application of the scheme for a partial break of a curved dam test problem.

27 CFR 555.61 - Discontinuance of business or operations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Permits § 555.61 Discontinuance of business or operations. Where an explosive materials business or operations is either discontinued or succeeded by a new owner, the owner of the business or operations...

Porter's generic strategies, discontinuous environments, and performance: a longitudinal study of changing strategies in the hospital industry.

PubMed Central

Lamont, B T; Marlin, D; Hoffman, J J

1993-01-01

OBJECTIVE. Changes in generic strategies in response to discontinuous environments have been relatively ignored in the management literature. This study reports an examination of the relationships between Porter's (1980) generic strategies, discontinuous environments, and performance. DATA SOURCES. Archival data for 1984 and 1988 were collected for 172 acute care hospitals in Florida in order to test these relationships. STUDY DESIGN. To examine fully the performance impact of changes in strategy in a discontinuous environment, a longitudinal research design that identified a firm's strategy at two points in time, 1984 and 1988, was used. PRINCIPAL FINDINGS. Results indicate that firms with a proper strategy environment fit performed the highest, firms that did not change their strategy had no change in performance, and firms that changed their strategy toward a proper strategy environment showed an increase in performance. CONCLUSION. Findings support the notion that hospitals with appropriate strategy-environment combinations will exhibit higher performance. PMID:8270424

Local Discontinuous Galerkin Methods for Partial Differential Equations with Higher Order Derivatives

NASA Technical Reports Server (NTRS)

Yan, Jue; Shu, Chi-Wang; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

In this paper we review the existing and develop new continuous Galerkin methods for solving time dependent partial differential equations with higher order derivatives in one and multiple space dimensions. We review local discontinuous Galerkin methods for convection diffusion equations involving second derivatives and for KdV type equations involving third derivatives. We then develop new local discontinuous Galerkin methods for the time dependent bi-harmonic type equations involving fourth derivatives, and partial differential equations involving fifth derivatives. For these new methods we present correct interface numerical fluxes and prove L(exp 2) stability for general nonlinear problems. Preliminary numerical examples are shown to illustrate these methods. Finally, we present new results on a post-processing technique, originally designed for methods with good negative-order error estimates, on the local discontinuous Galerkin methods applied to equations with higher derivatives. Numerical experiments show that this technique works as well for the new higher derivative cases, in effectively doubling the rate of convergence with negligible additional computational cost, for linear as well as some nonlinear problems, with a local uniform mesh.

14 CFR 221.300 - Discontinuation of electronic tariff system.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Discontinuation of electronic tariff system... of electronic tariff system. In the event that the electronic tariff system is discontinued, or the source of the data is changed, or a filer discontinues its business, all electronic data records prior to...

14 CFR 221.300 - Discontinuation of electronic tariff system.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Discontinuation of electronic tariff system... of electronic tariff system. In the event that the electronic tariff system is discontinued, or the source of the data is changed, or a filer discontinues its business, all electronic data records prior to...

14 CFR 221.300 - Discontinuation of electronic tariff system.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Discontinuation of electronic tariff system... of electronic tariff system. In the event that the electronic tariff system is discontinued, or the source of the data is changed, or a filer discontinues its business, all electronic data records prior to...

14 CFR 221.300 - Discontinuation of electronic tariff system.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Discontinuation of electronic tariff system... of electronic tariff system. In the event that the electronic tariff system is discontinued, or the source of the data is changed, or a filer discontinues its business, all electronic data records prior to...

Block Volume Estimation from the Discontinuity Spacing Measurements of Mesozoic Limestone Quarries, Karaburun Peninsula, Turkey

PubMed Central

Elci, Hakan; Turk, Necdet

2014-01-01

Block volumes are generally estimated by analyzing the discontinuity spacing measurements obtained either from the scan lines placed over the rock exposures or the borehole cores. Discontinuity spacing measurements made at the Mesozoic limestone quarries in Karaburun Peninsula were used to estimate the average block volumes that could be produced from them using the suggested methods in the literature. The Block Quality Designation (BQD) ratio method proposed by the authors has been found to have given in the same order of the rock block volume to the volumetric joint count (J v) method. Moreover, dimensions of the 2378 blocks produced between the years of 2009 and 2011 in the working quarries have been recorded. Assuming, that each block surfaces is a discontinuity, the mean block volume (V b), the mean volumetric joint count (J vb) and the mean block shape factor of the blocks are determined and compared with the estimated mean in situ block volumes (V in) and volumetric joint count (J vi) values estimated from the in situ discontinuity measurements. The established relations are presented as a chart to be used in practice for estimating the mean volume of blocks that can be obtained from a quarry site by analyzing the rock mass discontinuity spacing measurements. PMID:24696642

Block volume estimation from the discontinuity spacing measurements of mesozoic limestone quarries, Karaburun Peninsula, Turkey.

PubMed

Elci, Hakan; Turk, Necdet

2014-01-01

Block volumes are generally estimated by analyzing the discontinuity spacing measurements obtained either from the scan lines placed over the rock exposures or the borehole cores. Discontinuity spacing measurements made at the Mesozoic limestone quarries in Karaburun Peninsula were used to estimate the average block volumes that could be produced from them using the suggested methods in the literature. The Block Quality Designation (BQD) ratio method proposed by the authors has been found to have given in the same order of the rock block volume to the volumetric joint count (J(v)) method. Moreover, dimensions of the 2378 blocks produced between the years of 2009 and 2011 in the working quarries have been recorded. Assuming, that each block surfaces is a discontinuity, the mean block volume (V(b)), the mean volumetric joint count (J(vb)) and the mean block shape factor of the blocks are determined and compared with the estimated mean in situ block volumes (V(in)) and volumetric joint count (J(vi)) values estimated from the in situ discontinuity measurements. The established relations are presented as a chart to be used in practice for estimating the mean volume of blocks that can be obtained from a quarry site by analyzing the rock mass discontinuity spacing measurements.

27 CFR 44.161 - Discontinuance of operations.

Code of Federal Regulations, 2010 CFR

2010-04-01

... operations. 44.161 Section 44.161 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Operations § 44.161 Discontinuance of operations. Every export warehouse proprietor who desires to discontinue operations and close out his warehouse shall dispose of all cigars, cigarettes, and cigarette...

Statistical methods for efficient design of community surveys of response to noise: Random coefficients regression models

NASA Technical Reports Server (NTRS)

Tomberlin, T. J.

1985-01-01

Research studies of residents' responses to noise consist of interviews with samples of individuals who are drawn from a number of different compact study areas. The statistical techniques developed provide a basis for those sample design decisions. These techniques are suitable for a wide range of sample survey applications. A sample may consist of a random sample of residents selected from a sample of compact study areas, or in a more complex design, of a sample of residents selected from a sample of larger areas (e.g., cities). The techniques may be applied to estimates of the effects on annoyance of noise level, numbers of noise events, the time-of-day of the events, ambient noise levels, or other factors. Methods are provided for determining, in advance, how accurately these effects can be estimated for different sample sizes and study designs. Using a simple cost function, they also provide for optimum allocation of the sample across the stages of the design for estimating these effects. These techniques are developed via a regression model in which the regression coefficients are assumed to be random, with components of variance associated with the various stages of a multi-stage sample design.

Continuity and Discontinuity: The Case of Second Couplehood in Old Age

ERIC Educational Resources Information Center

Koren, Chaya

2011-01-01

Purpose: Continuity and discontinuity are controversial concepts in social theories on aging. The aim of this article is to explore these concepts using the experiences of older persons living in second couplehood in old age as a case in point. Design and Method: Based on a larger qualitative study on second couplehood in old age, following the…

Evaluating Effects of Developmental Education for College Students Using a Regression Discontinuity Design

ERIC Educational Resources Information Center

Moss, Brian G.; Yeaton, William H.

2013-01-01

Background: Annually, American colleges and universities provide developmental education (DE) to millions of underprepared students; however, evaluation estimates of DE benefits have been mixed. Objectives: Using a prototypic exemplar of DE, our primary objective was to investigate the utility of a replicative evaluative framework for assessing…

PML-IRIS during Fingolimod Diagnosed after Natalizumab Discontinuation.

PubMed

Killestein, J; Vennegoor, A; van Golde, A E L; Bourez, R L J H; Wijlens, M L B; Wattjes, M P

2014-01-01

Background. Natalizumab treatment is frequently discontinued and replaced by alternative medication in multiple sclerosis (MS) patients having a high risk of progressive multifocal leukoencephalopathy (PML). Case Presentation. We report a PML case that was missed on magnetic resonance imaging (MRI) at the time Natalizumab treatment was discontinued. The patient subsequently developed a PML-immune reconstitution inflammatory syndrome after the initiation of Fingolimod treatment, suggesting that immune reconstitution may occur even during Fingolimod induced lymphopenia. Conclusion. This report highlights the need for strict drug surveillance using MRI of Natalizumab-associated MS patients at the time of drug discontinuation and beyond. This is important with respect to pharmacovigilance purposes not only for Natalizumab, but also for alternative drugs used after Natalizumab discontinuation.

Analysis of shielded CPW discontinuities with air-bridges

NASA Technical Reports Server (NTRS)

Dib, N. I.; Katehi, P. B.; Ponchak, George E.

1992-01-01

The effect of air-bridges on the performance of various coplanar waveguides (CPW) discontinuities is studied. Specifically, the coupled open-end CPW's and the short-end shunt CPW stub discontinuities are considered. The high frequency effect of the air-bridge is evaluated using a hybrid technique. At first, the frequency dependent equivalent circuit of the planar discontinuity without the air-bridge is derived using the Space Domain Integral Equation (SDIE) method. Then, the circuit is modified by incorporating the air-bridge's parasitic inductance and capacitance which are evaluated using a simple quasi-static model. The frequency response of each discontinuity with and without the air-bridge is studied and the scattering parameters are plotted in the frequency range 30-50 GHz for typical CPW dimensions.

Evaluating differential effects using regression interactions and regression mixture models

PubMed Central

Van Horn, M. Lee; Jaki, Thomas; Masyn, Katherine; Howe, George; Feaster, Daniel J.; Lamont, Andrea E.; George, Melissa R. W.; Kim, Minjung

2015-01-01

Research increasingly emphasizes understanding differential effects. This paper focuses on understanding regression mixture models, a relatively new statistical methods for assessing differential effects by comparing results to using an interactive term in linear regression. The research questions which each model answers, their formulation, and their assumptions are compared using Monte Carlo simulations and real data analysis. The capabilities of regression mixture models are described and specific issues to be addressed when conducting regression mixtures are proposed. The paper aims to clarify the role that regression mixtures can take in the estimation of differential effects and increase awareness of the benefits and potential pitfalls of this approach. Regression mixture models are shown to be a potentially effective exploratory method for finding differential effects when these effects can be defined by a small number of classes of respondents who share a typical relationship between a predictor and an outcome. It is also shown that the comparison between regression mixture models and interactions becomes substantially more complex as the number of classes increases. It is argued that regression interactions are well suited for direct tests of specific hypotheses about differential effects and regression mixtures provide a useful approach for exploring effect heterogeneity given adequate samples and study design. PMID:26556903

Hyperspherical Sparse Approximation Techniques for High-Dimensional Discontinuity Detection

DOE PAGES

Zhang, Guannan; Webster, Clayton G.; Gunzburger, Max; ...

2016-08-04

This work proposes a hyperspherical sparse approximation framework for detecting jump discontinuities in functions in high-dimensional spaces. The need for a novel approach results from the theoretical and computational inefficiencies of well-known approaches, such as adaptive sparse grids, for discontinuity detection. Our approach constructs the hyperspherical coordinate representation of the discontinuity surface of a function. Then sparse approximations of the transformed function are built in the hyperspherical coordinate system, with values at each point estimated by solving a one-dimensional discontinuity detection problem. Due to the smoothness of the hypersurface, the new technique can identify jump discontinuities with significantly reduced computationalmore » cost, compared to existing methods. Several approaches are used to approximate the transformed discontinuity surface in the hyperspherical system, including adaptive sparse grid and radial basis function interpolation, discrete least squares projection, and compressed sensing approximation. Moreover, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. In conclusion, rigorous complexity analyses of the new methods are provided, as are several numerical examples that illustrate the effectiveness of our approach.« less

Reasons for discontinuation of reversible contraceptive methods by women with epilepsy.

PubMed

Mandle, Hannah B; Cahill, Kaitlyn E; Fowler, Kristen M; Hauser, W Allen; Davis, Anne R; Herzog, Andrew G

2017-05-01

To report the reasons for discontinuation of contraceptive methods by women with epilepsy (WWE). These retrospective data come from a web-based survey regarding the contraceptive practices of 1,144 WWE in the community, ages 18-47 years. We determined the frequencies of contraceptive discontinuations and the reasons for discontinuation. We compared risk ratios for rates of discontinuation among contraceptive methods and categories. We used chi-square analysis to test the independence of discontinuation reasons among the various contraceptive methods and categories and when stratified by antiepileptic drug (AED) categories. Nine hundred fifty-nine of 2,393 (40.6%) individual, reversible contraceptive methods were discontinued. One-half (51.8%) of the WWE who discontinued a method discontinued at least two methods. Hormonal contraception was discontinued most often (553/1,091, 50.7%) with a risk ratio of 1.94 (1.54-2.45, p < 0.0001) compared to intrauterine devices (IUDs), the category that was discontinued the least (57/227, 25.1%). Among all individual methods, the contraceptive patch was stopped most often (79.7%) and the progestin-IUD was stopped the least (20.1%). The top three reasons for discontinuation among all methods were reliability concerns (13.9%), menstrual problems (13.5%), and increased seizures (8.6%). There were significant differences among discontinuation rates and reasons when stratified by AED category for hormonal contraception but not for any other contraceptive category. Contraception counseling for WWE should consider the special experience profiles that are unique to this special population on systemic hormonal contraception. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

Continuous and discontinuous transitions to synchronization.

PubMed

Wang, Chaoqing; Garnier, Nicolas B

2016-11-01

We describe how the transition to synchronization in a system of globally coupled Stuart-Landau oscillators changes from continuous to discontinuous when the nature of the coupling is moved from diffusive to reactive. We explain this drastic qualitative change as resulting from the co-existence of a particular synchronized macrostate together with the trivial incoherent macrostate, in a range of parameter values for which the latter is linearly stable. In contrast to the paradigmatic Kuramoto model, this particular state observed at the synchronization transition contains a finite, non-vanishing number of synchronized oscillators, which results in a discontinuous transition. We consider successively two situations where either a fully synchronized state or a partially synchronized state exists at the transition. Thermodynamic limit and finite size effects are briefly discussed, as well as connections with recently observed discontinuous transitions.

27 CFR 31.138 - Discontinuance of business.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Discontinuance of business. 31.138 Section 31.138 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... § 31.138 Discontinuance of business. A dealer going out of business must register that event within 30...

A methodology for the design of experiments in computational intelligence with multiple regression models.

PubMed

Fernandez-Lozano, Carlos; Gestal, Marcos; Munteanu, Cristian R; Dorado, Julian; Pazos, Alejandro

2016-01-01

The design of experiments and the validation of the results achieved with them are vital in any research study. This paper focuses on the use of different Machine Learning approaches for regression tasks in the field of Computational Intelligence and especially on a correct comparison between the different results provided for different methods, as those techniques are complex systems that require further study to be fully understood. A methodology commonly accepted in Computational intelligence is implemented in an R package called RRegrs. This package includes ten simple and complex regression models to carry out predictive modeling using Machine Learning and well-known regression algorithms. The framework for experimental design presented herein is evaluated and validated against RRegrs. Our results are different for three out of five state-of-the-art simple datasets and it can be stated that the selection of the best model according to our proposal is statistically significant and relevant. It is of relevance to use a statistical approach to indicate whether the differences are statistically significant using this kind of algorithms. Furthermore, our results with three real complex datasets report different best models than with the previously published methodology. Our final goal is to provide a complete methodology for the use of different steps in order to compare the results obtained in Computational Intelligence problems, as well as from other fields, such as for bioinformatics, cheminformatics, etc., given that our proposal is open and modifiable.

A methodology for the design of experiments in computational intelligence with multiple regression models

PubMed Central

Gestal, Marcos; Munteanu, Cristian R.; Dorado, Julian; Pazos, Alejandro

2016-01-01

The design of experiments and the validation of the results achieved with them are vital in any research study. This paper focuses on the use of different Machine Learning approaches for regression tasks in the field of Computational Intelligence and especially on a correct comparison between the different results provided for different methods, as those techniques are complex systems that require further study to be fully understood. A methodology commonly accepted in Computational intelligence is implemented in an R package called RRegrs. This package includes ten simple and complex regression models to carry out predictive modeling using Machine Learning and well-known regression algorithms. The framework for experimental design presented herein is evaluated and validated against RRegrs. Our results are different for three out of five state-of-the-art simple datasets and it can be stated that the selection of the best model according to our proposal is statistically significant and relevant. It is of relevance to use a statistical approach to indicate whether the differences are statistically significant using this kind of algorithms. Furthermore, our results with three real complex datasets report different best models than with the previously published methodology. Our final goal is to provide a complete methodology for the use of different steps in order to compare the results obtained in Computational Intelligence problems, as well as from other fields, such as for bioinformatics, cheminformatics, etc., given that our proposal is open and modifiable. PMID:27920952

Correlation and simple linear regression.

PubMed

Eberly, Lynn E

2007-01-01

This chapter highlights important steps in using correlation and simple linear regression to address scientific questions about the association of two continuous variables with each other. These steps include estimation and inference, assessing model fit, the connection between regression and ANOVA, and study design. Examples in microbiology are used throughout. This chapter provides a framework that is helpful in understanding more complex statistical techniques, such as multiple linear regression, linear mixed effects models, logistic regression, and proportional hazards regression.

Malpractice Burden, Rural Location, and Discontinuation of Obstetric Care: A Study of Obstetric Providers in Michigan

PubMed Central

Xu, Xiao; Siefert, Kristine A.; Jacobson, Peter D.; Lori, Jody R.; Gueorguieva, Iana; Ransom, Scott B.

2011-01-01

Context It has long been a concern that professional liability problems disproportionately affect the delivery of obstetrical services to women living in rural areas. Michigan, a state with a large number of rural communities, is considered to be at risk for a medical liability crisis. Purpose This study examined whether higher malpractice burden on obstetric providers was associated with an increased likelihood of discontinuing obstetric care and whether there were rural-urban differences in the relationship. Methods Data on 500 obstetrician-gynecologists and family physicians who had provided obstetric care at some point in their career (either currently or previously) were obtained from a statewide survey in Michigan. Statistical tests and multivariate regression analyses were performed to examine the interrelationship among malpractice burden, rural location, and discontinuation of obstetric care. Findings After adjusting for other factors that might influence a physician’s decision about whether to stop obstetric care, our results showed no significant impact of malpractice burden on physicians’ likelihood to discontinue obstetric care. Rural-urban location of the practice did not modify the nature of this relationship. However, family physicians in rural Michigan had a nearly four fold higher likelihood of withdrawing obstetric care when compared to urban family physicians. Conclusions The higher likelihood of rural family physicians to discontinue obstetric care should be carefully weighed in future interventions to preserve obstetric care supply. More research is needed to better understand the practice environment of rural family physicians and the reasons for their withdrawal from obstetric care. PMID:19166559

41 CFR 109-39.105 - Discontinuance or curtailment of service.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 39-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.1-Establishment, Modification, and Discontinuance of Interagency Fleet Management Systems § 109-39.105 Discontinuance or... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Discontinuance or...

What happens when people discontinue taking medications? Lessons from COMBINE.

PubMed

Stout, Robert L; Braciszewski, Jordan M; Subbaraman, Meenakshi Sabina; Kranzler, Henry R; O'Malley, Stephanie S; Falk, Daniel

2014-12-01

We use intensive longitudinal data methods to illuminate processes affecting patients' drinking in relation to the discontinuation of medications within an alcohol treatment study. Although previous work has focused on broad measures of medication adherence, we focus on dynamic changes in drinking both before and after patients discontinue. We conducted secondary data analyses using the COMBINE (Combined Pharmacotherapies and Behavioral Interventions for Alcohol Dependence) study, focused on participants who discontinued medications prior to the planned end of treatment. Using an interrupted time-series analysis, we analysed drinking in the weeks before and after discontinuation and also studied outcomes at the end of the COMBINE follow-up. Unites States of America. We describe the subsample of COMBINE participants who discontinued medications (n = 450), and compare them with those who were medication-adherent (n = 559) and with those who discontinued but had substantial missing data (n = 217). The primary outcomes were percentage of days abstinent (PDA) and percentage of heavy drinking days (PHDD). Medication adherence data were used to approximate the date of discontinuation. For many patients, an increase in drinking began weeks before discontinuation (PDA: F(1,4803) = 19.07, P < 0.001; PHDD: F(1,4804) = 8.58, P = 0.003) then escalated at discontinuation (PDA: F(1,446) = 5.05, P = 0.025; PHDD: F(1,446) = 4.52, P = 0.034). Among other effects, the amount of change was moderated by the reason for discontinuation (e.g. adverse event; PDA: F(2,4803) = 3.85, P = 0.021; PHDD: F(2,4804) = 5.36, P = 0.005) and also whether it occurred in the first or second half of treatment (PDA: F(1,4803) = 5.23, P = 0.022; PHDD: F(1,4804) = 8.79, P = 0.003). A patient's decision to stop taking medications during alcohol treatment appears to take place during a weeks-long process of disengagement from treatment. Patients who discontinue medications early in treatment or without

Finite-time robust stabilization of uncertain delayed neural networks with discontinuous activations via delayed feedback control.

PubMed

Wang, Leimin; Shen, Yi; Sheng, Yin

2016-04-01

This paper is concerned with the finite-time robust stabilization of delayed neural networks (DNNs) in the presence of discontinuous activations and parameter uncertainties. By using the nonsmooth analysis and control theory, a delayed controller is designed to realize the finite-time robust stabilization of DNNs with discontinuous activations and parameter uncertainties, and the upper bound of the settling time functional for stabilization is estimated. Finally, two examples are provided to demonstrate the effectiveness of the theoretical results. Copyright © 2016 Elsevier Ltd. All rights reserved.

Linear Multivariable Regression Models for Prediction of Eddy Dissipation Rate from Available Meteorological Data

NASA Technical Reports Server (NTRS)

MCKissick, Burnell T. (Technical Monitor); Plassman, Gerald E.; Mall, Gerald H.; Quagliano, John R.

2005-01-01

Linear multivariable regression models for predicting day and night Eddy Dissipation Rate (EDR) from available meteorological data sources are defined and validated. Model definition is based on a combination of 1997-2000 Dallas/Fort Worth (DFW) data sources, EDR from Aircraft Vortex Spacing System (AVOSS) deployment data, and regression variables primarily from corresponding Automated Surface Observation System (ASOS) data. Model validation is accomplished through EDR predictions on a similar combination of 1994-1995 Memphis (MEM) AVOSS and ASOS data. Model forms include an intercept plus a single term of fixed optimal power for each of these regression variables; 30-minute forward averaged mean and variance of near-surface wind speed and temperature, variance of wind direction, and a discrete cloud cover metric. Distinct day and night models, regressing on EDR and the natural log of EDR respectively, yield best performance and avoid model discontinuity over day/night data boundaries.

Accountability Accentuates Interindividual-Intergroup Discontinuity by Enforcing Parochialism.

PubMed

Wildschut, Tim; van Horen, Femke; Hart, Claire

2015-01-01

Interindividual-intergroup discontinuity is the tendency for relations between groups to be more competitive than relations between individuals. We examined whether the discontinuity effect arises in part because group members experience normative pressure to favor the ingroup (parochialism). Building on the notion that accountability enhances normative pressure, we hypothesized that the discontinuity effect would be larger when accountability is present (compared to absent). A prisoner's dilemma game experiment supported this prediction. Specifically, intergroup (compared to interindividual) interaction activated an injunctive ingroup-favoring norm, and accountability enhanced the influence of this norm on competitive behavior.

Discontinuously Stiffened Composite Panel under Compressive Loading

NASA Technical Reports Server (NTRS)

Minnetyan, Levon; Rivers, James M.; Chamis, Christos C.; Murthy, Pappu L. N.

1995-01-01

The design of composite structures requires an evaluation of their safety and durability under service loads and possible overload conditions. This paper presents a computational tool that has been developed to examine the response of stiffened composite panels via the simulation of damage initiation, growth, accumulation, progression, and propagation to structural fracture or collapse. The structural durability of a composite panel with a discontinuous stiffener is investigated under compressive loading induced by the gradual displacement of an end support. Results indicate damage initiation and progression to have significant effects on structural behavior under loading. Utilization of an integrated computer code for structural durability assessment is demonstrated.

Discontinuation of Tocolytics for Preterm Labor in an Academic Safety Net Hospital: Impact on the Duration of Betamethasone Exposure.

PubMed

Alston, Meredith J; Alexandrovic, Kara; Stiglich, Norma; Metz, Torri D

2016-01-01

To evaluate the impact of discontinuation of tocolytics on the completion of the corticosteroid course among preterm neonates in an academic safety net hospital. Retrospective cohort study of all singleton pregnancies with preterm labor resulting in delivery between 24 and 34 weeks' gestation at Denver Health Medical Center (DHMC) between 1/1/2004 and 5/31/2009. In January 2007 DHMC discontinued the use of tocolytic therapy for preterm labor. Study subjects were grouped based on whether their delivery occurred before or after the change in policy. Multivariable logistic regression was used to determine whether the use of tocolysis increased the odds of completion of the betamethasone while adjusting for cervical examination at admission. Of 169 infant/mother pairs who met inclusion criteria, 102 delivered prior to the discontinuation of tocolytics and 67 delivered after the discontinuation of tocolytics. Treatment with tocolysis increased the odds of completing the 48-hour betamethasone window (OR 2.59, 95% CI 1.16-5.79). Each centimeter increase in cervical dilation at the time of admission decreased the odds of completing the betamethasone window (OR 0.50, 95% CI 0.39-0.62). The use of tocolytics increased the odds of completion of the betamethasone window in an academic safety net hospital among neonates born between 24 and 34 weeks' gestation.

The Entrepreneurship Bootcamp for Veterans' Families Program: Transformative Learning for Discontinuous Life Transition

ERIC Educational Resources Information Center

Redmon, Stephen Thomas

2013-01-01

This multiple-case study explored the nature of the experiences of family members of service-disabled veterans who participated in the Entrepreneurship Bootcamp for Veterans Family Program (EBV-F), an entrepreneurial learning and coaching program designed to assist family members of service-disabled veterans to support the discontinuous life…

14 CFR Section 16 - Objective Classification-Discontinued Operations

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Objective Classification-Discontinued Operations Section 16 Section 16 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION... AIR CARRIERS Profit and Loss Classification Section 16 Objective Classification—Discontinued...

Physics-based process model approach for detecting discontinuity during friction stir welding

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

Shrivastava, Amber; Pfefferkorn, Frank E.; Duffie, Neil A.

2015-02-12

The goal of this work is to develop a method for detecting the creation of discontinuities during friction stir welding. This in situ weld monitoring method could significantly reduce the need for post-process inspection. A process force model and a discontinuity force model were created based on the state-of-the-art understanding of flow around an friction stir welding (FSW) tool. These models are used to predict the FSW forces and size of discontinuities formed in the weld. Friction stir welds with discontinuities and welds without discontinuities were created, and the differences in force dynamics were observed. In this paper, discontinuities weremore » generated by reducing the tool rotation frequency and increasing the tool traverse speed in order to create "cold" welds. Experimental force data for welds with discontinuities and welds without discontinuities compared favorably with the predicted forces. The model currently overpredicts the discontinuity size.« less

Discontinuing Pneumocystis jirovecii Pneumonia Prophylaxis in HIV-Infected Patients With a CD4 Cell Count <200 cells/mm3.

PubMed

Sidhu, Vaninder K; Foisy, Michelle M; Hughes, Christine A

2015-12-01

To review the evidence for discontinuing primary and secondary Pneumocystis jirovecii pneumonia (PJP) prophylaxis in HIV-infected patients with a CD4 count <200 cells/mm(3). We conducted a literature search in MEDLINE, EMBASE, Cochrane Library, Google Scholar, and the International Aids Society Library (up to August 2015) using the following key search terms: Pneumocystis jirovecii, pneumonia, human immunodeficiency virus, primary prophylaxis, secondary prophylaxis, and discontinuation. All English-language studies that evaluated discontinuation of primary and/or secondary PJP prophylaxis in HIV-infected patients with CD4 count <200 cells/mm(3) were included. Five studies were identified, which varied in design, sample size, outcomes, and duration of follow-up. Three studies examined discontinuation of primary and secondary PJP prophylaxis; 1 study evaluated discontinuing primary PJP prophylaxis; and 1 study evaluated stopping secondary PJP prophylaxis. Two out of the 5 studies pooled data for all opportunistic infections. Overall, there was a low incidence of PJP among HIV-infected patients who discontinued primary PJP prophylaxis and were well controlled on antiretroviral therapy (ART). Discontinuation of primary PJP prophylaxis appears to be safe in patients on combination ART with a suppressed HIV viral load and a CD4 count >100 cells/mm(3). Additional data are needed to support the safety of discontinuing secondary PJP prophylaxis. Decisions to discontinue PJP prophylaxis in patients with a CD4 count <200 cells/mm(3) should be done on an individual patient basis, taking into consideration clinical factors, including ongoing adherence to ART. © The Author(s) 2015.

Discontinuous dual-primal mixed finite elements for elliptic problems

NASA Technical Reports Server (NTRS)

Bottasso, Carlo L.; Micheletti, Stefano; Sacco, Riccardo

2000-01-01

We propose a novel discontinuous mixed finite element formulation for the solution of second-order elliptic problems. Fully discontinuous piecewise polynomial finite element spaces are used for the trial and test functions. The discontinuous nature of the test functions at the element interfaces allows to introduce new boundary unknowns that, on the one hand enforce the weak continuity of the trial functions, and on the other avoid the need to define a priori algorithmic fluxes as in standard discontinuous Galerkin methods. Static condensation is performed at the element level, leading to a solution procedure based on the sole interface unknowns. The resulting family of discontinuous dual-primal mixed finite element methods is presented in the one and two-dimensional cases. In the one-dimensional case, we show the equivalence of the method with implicit Runge-Kutta schemes of the collocation type exhibiting optimal behavior. Numerical experiments in one and two dimensions demonstrate the order accuracy of the new method, confirming the results of the analysis.

Uncertainty Quantification given Discontinuous Climate Model Response and a Limited Number of Model Runs

NASA Astrophysics Data System (ADS)

Sargsyan, K.; Safta, C.; Debusschere, B.; Najm, H.

2010-12-01

Uncertainty quantification in complex climate models is challenged by the sparsity of available climate model predictions due to the high computational cost of model runs. Another feature that prevents classical uncertainty analysis from being readily applicable is bifurcative behavior in climate model response with respect to certain input parameters. A typical example is the Atlantic Meridional Overturning Circulation. The predicted maximum overturning stream function exhibits discontinuity across a curve in the space of two uncertain parameters, namely climate sensitivity and CO2 forcing. We outline a methodology for uncertainty quantification given discontinuous model response and a limited number of model runs. Our approach is two-fold. First we detect the discontinuity with Bayesian inference, thus obtaining a probabilistic representation of the discontinuity curve shape and location for arbitrarily distributed input parameter values. Then, we construct spectral representations of uncertainty, using Polynomial Chaos (PC) expansions on either side of the discontinuity curve, leading to an averaged-PC representation of the forward model that allows efficient uncertainty quantification. The approach is enabled by a Rosenblatt transformation that maps each side of the discontinuity to regular domains where desirable orthogonality properties for the spectral bases hold. We obtain PC modes by either orthogonal projection or Bayesian inference, and argue for a hybrid approach that targets a balance between the accuracy provided by the orthogonal projection and the flexibility provided by the Bayesian inference - where the latter allows obtaining reasonable expansions without extra forward model runs. The model output, and its associated uncertainty at specific design points, are then computed by taking an ensemble average over PC expansions corresponding to possible realizations of the discontinuity curve. The methodology is tested on synthetic examples of

47 CFR 1.764 - Discontinuance, reduction, or impairment of service.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Discontinuance, reduction, or impairment of... Applications Under Title II of Communications Act § 1.764 Discontinuance, reduction, or impairment of service... discontinuance, reduction, or impairment of service shall be made in the form and manner, with the number of...

47 CFR 90.157 - Discontinuance of station operation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Discontinuance of station operation. 90.157 Section 90.157 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Applications and Authorizations § 90.157 Discontinuance of...

An analysis of the personal reasons for discontinuing IUD use.

PubMed

Petta, C A; Amatya, R; Farr, G; Chi, I

1994-10-01

The objective of this study was to evaluate possible factors associated with discontinuing use of TCu 380A IUDs due to personal reasons among 2748 users. Overall, a total of 88 subjects discontinued using the TCu 380A IUD within 12 months postinsertion for personal reasons. The most common reasons were planned pregnancy (32%) and husband or family opinion against IUD use (26%). The gross cumulative 12-month life table discontinuation rate for all personal reasons was 4.0 per 100 women. Having no education and/or living in a rural area were the sociodemographic characteristics associated with an increased risk of discontinuation for personal reasons. Effective and regular counseling about IUD use, especially among illiterate women, may help prevent IUD discontinuations related to personal reasons.

Geographically weighted regression as a generalized Wombling to detect barriers to gene flow.

PubMed

Diniz-Filho, José Alexandre Felizola; Soares, Thannya Nascimento; de Campos Telles, Mariana Pires

2016-08-01

Barriers to gene flow play an important role in structuring populations, especially in human-modified landscapes, and several methods have been proposed to detect such barriers. However, most applications of these methods require a relative large number of individuals or populations distributed in space, connected by vertices from Delaunay or Gabriel networks. Here we show, using both simulated and empirical data, a new application of geographically weighted regression (GWR) to detect such barriers, modeling the genetic variation as a "local" linear function of geographic coordinates (latitude and longitude). In the GWR, standard regression statistics, such as R(2) and slopes, are estimated for each sampling unit and thus are mapped. Peaks in these local statistics are then expected close to the barriers if genetic discontinuities exist, capturing a higher rate of population differentiation among neighboring populations. Isolation-by-Distance simulations on a longitudinally warped lattice revealed that higher local slopes from GWR coincide with the barrier detected with Monmonier algorithm. Even with a relatively small effect of the barrier, the power of local GWR in detecting the east-west barriers was higher than 95 %. We also analyzed empirical data of genetic differentiation among tree populations of Dipteryx alata and Eugenia dysenterica Brazilian Cerrado. GWR was applied to the principal coordinate of the pairwise FST matrix based on microsatellite loci. In both simulated and empirical data, the GWR results were consistent with discontinuities detected by Monmonier algorithm, as well as with previous explanations for the spatial patterns of genetic differentiation for the two species. Our analyses reveal how this new application of GWR can viewed as a generalized Wombling in a continuous space and be a useful approach to detect barriers and discontinuities to gene flow.

Accountability Accentuates Interindividual-Intergroup Discontinuity by Enforcing Parochialism

PubMed Central

Wildschut, Tim; van Horen, Femke; Hart, Claire

2015-01-01

Interindividual-intergroup discontinuity is the tendency for relations between groups to be more competitive than relations between individuals. We examined whether the discontinuity effect arises in part because group members experience normative pressure to favor the ingroup (parochialism). Building on the notion that accountability enhances normative pressure, we hypothesized that the discontinuity effect would be larger when accountability is present (compared to absent). A prisoner’s dilemma game experiment supported this prediction. Specifically, intergroup (compared to interindividual) interaction activated an injunctive ingroup-favoring norm, and accountability enhanced the influence of this norm on competitive behavior. PMID:26635691

A second order discontinuous Galerkin fast sweeping method for Eikonal equations

NASA Astrophysics Data System (ADS)

Li, Fengyan; Shu, Chi-Wang; Zhang, Yong-Tao; Zhao, Hongkai

2008-09-01

In this paper, we construct a second order fast sweeping method with a discontinuous Galerkin (DG) local solver for computing viscosity solutions of a class of static Hamilton-Jacobi equations, namely the Eikonal equations. Our piecewise linear DG local solver is built on a DG method developed recently [Y. Cheng, C.-W. Shu, A discontinuous Galerkin finite element method for directly solving the Hamilton-Jacobi equations, Journal of Computational Physics 223 (2007) 398-415] for the time-dependent Hamilton-Jacobi equations. The causality property of Eikonal equations is incorporated into the design of this solver. The resulting local nonlinear system in the Gauss-Seidel iterations is a simple quadratic system and can be solved explicitly. The compactness of the DG method and the fast sweeping strategy lead to fast convergence of the new scheme for Eikonal equations. Extensive numerical examples verify efficiency, convergence and second order accuracy of the proposed method.

Discontinuous precipitation at the deformation band in copper alloy

NASA Astrophysics Data System (ADS)

Han, Seung Zeon; Ahn, Jee Hyuk; You, Young Soo; Lee, Jehyun; Goto, Masahiro; Kim, Kwangho; Kim, Sangshik

2018-01-01

The Cu-Ni-Si alloy is known as a precipitation hardening alloy, where the Ni2Si intermetallic compound is precipitated in the matrix during aging. There are two types of precipitation of Ni2Si: continuous and discontinuous cellular. The discontinuous cellular precipitation is generally initiated at interfaces especially grain boundaries in the matrix. To observe the grain boundary effect on the discontinuous precipitation, a large-grained Cu-Ni-Si-Ti alloy was intentionally fabricated by unidirectional solidification and plastically deformed by groove rolling. While discontinuous cellular precipitation has been generally known to occur only at the high angled grain boundaries in the alloys, we found that it was also generated inside the grains, at the deformation bands formed by plastic deformation.

Distributed collaborative probabilistic design of multi-failure structure with fluid-structure interaction using fuzzy neural network of regression

NASA Astrophysics Data System (ADS)

Song, Lu-Kai; Wen, Jie; Fei, Cheng-Wei; Bai, Guang-Chen

2018-05-01

To improve the computing efficiency and precision of probabilistic design for multi-failure structure, a distributed collaborative probabilistic design method-based fuzzy neural network of regression (FR) (called as DCFRM) is proposed with the integration of distributed collaborative response surface method and fuzzy neural network regression model. The mathematical model of DCFRM is established and the probabilistic design idea with DCFRM is introduced. The probabilistic analysis of turbine blisk involving multi-failure modes (deformation failure, stress failure and strain failure) was investigated by considering fluid-structure interaction with the proposed method. The distribution characteristics, reliability degree, and sensitivity degree of each failure mode and overall failure mode on turbine blisk are obtained, which provides a useful reference for improving the performance and reliability of aeroengine. Through the comparison of methods shows that the DCFRM reshapes the probability of probabilistic analysis for multi-failure structure and improves the computing efficiency while keeping acceptable computational precision. Moreover, the proposed method offers a useful insight for reliability-based design optimization of multi-failure structure and thereby also enriches the theory and method of mechanical reliability design.

The Harang discontinuity in auroral belt ionospheric currents.

NASA Technical Reports Server (NTRS)

Heppner, J. P.

1972-01-01

Discussion of the nature of a discontinuity in the ionospheric current of the auroral belt whose existence was suggested by Harang in 1946. Convection characteristics, time variability, and current continuity in the auroral belt are considered in a context of observations and arguments supporting the reality of Harang's discontinuity.

50 CFR 13.26 - Discontinuance of permit activity.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 1 2010-10-01 2010-10-01 false Discontinuance of permit activity. 13.26 Section 13.26 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... PLANTS GENERAL PERMIT PROCEDURES Permit Administration § 13.26 Discontinuance of permit activity. When a...

Fixed-time stability of dynamical systems and fixed-time synchronization of coupled discontinuous neural networks.

PubMed

Hu, Cheng; Yu, Juan; Chen, Zhanheng; Jiang, Haijun; Huang, Tingwen

2017-05-01

In this paper, the fixed-time stability of dynamical systems and the fixed-time synchronization of coupled discontinuous neural networks are investigated under the framework of Filippov solution. Firstly, by means of reduction to absurdity, a theorem of fixed-time stability is established and a high-precision estimation of the settling-time is given. It is shown by theoretic proof that the estimation bound of the settling time given in this paper is less conservative and more accurate compared with the classical results. Besides, as an important application, the fixed-time synchronization of coupled neural networks with discontinuous activation functions is proposed. By designing a discontinuous control law and using the theory of differential inclusions, some new criteria are derived to ensure the fixed-time synchronization of the addressed coupled networks. Finally, two numerical examples are provided to show the effectiveness and validity of the theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

Magnetic discontinuities in magnetohydrodynamic turbulence and in the solar wind.

PubMed

Zhdankin, Vladimir; Boldyrev, Stanislav; Mason, Joanne; Perez, Jean Carlos

2012-04-27

Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) turbulence. We detect the discontinuities by measuring the fluctuations of the magnetic field direction, Δθ, across fixed spatial increments Δx in direct numerical simulations of MHD turbulence with an imposed uniform guide field B(0). A large region of the probability density function (pdf) for Δθ is found to follow an exponential decay, proportional to exp(-Δθ/θ(*)), with characteristic angle θ(*)≈(14°)(b(rms)/B(0))(0.65) for a broad range of guide-field strengths. We find that discontinuities observed in the solar wind can be reproduced by MHD turbulence with reasonable ratios of b(rms)/B(0). We also observe an excess of small angular discontinuities when Δx becomes small, possibly indicating an increasing statistical significance of dissipation-scale structures. The structure of the pdf in this case closely resembles the two-population pdf seen in the solar wind. We thus propose that strong discontinuities are associated with inertial-range MHD turbulence, while weak discontinuities emerge from dissipation-range turbulence. In addition, we find that the structure functions of the magnetic field direction exhibit anomalous scaling exponents, which indicates the existence of intermittent structures.

27 CFR 19.19 - Discontinuance of storage facilities.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Discontinuance of storage... Provisions § 19.19 Discontinuance of storage facilities. If TTB determines that a proprietor's bonded storage... spirits stored in the facility to another storage facility. The transfer will take place at such time and...

27 CFR 19.79 - Discontinuance of storage facilities.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Discontinuance of storage... Provisions Activities Not Subject to This Part § 19.79 Discontinuance of storage facilities. When the appropriate TTB officer finds that any facilities for the storage of spirits on bonded premises are unsafe or...

27 CFR 19.19 - Discontinuance of storage facilities.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Discontinuance of storage... Provisions § 19.19 Discontinuance of storage facilities. If TTB determines that a proprietor's bonded storage... spirits stored in the facility to another storage facility. The transfer will take place at such time and...

Designs of Empirical Evaluations of Nonexperimental Methods in Field Settings.

PubMed

Wong, Vivian C; Steiner, Peter M

2018-01-01

Over the last three decades, a research design has emerged to evaluate the performance of nonexperimental (NE) designs and design features in field settings. It is called the within-study comparison (WSC) approach or the design replication study. In the traditional WSC design, treatment effects from a randomized experiment are compared to those produced by an NE approach that shares the same target population. The nonexperiment may be a quasi-experimental design, such as a regression-discontinuity or an interrupted time-series design, or an observational study approach that includes matching methods, standard regression adjustments, and difference-in-differences methods. The goals of the WSC are to determine whether the nonexperiment can replicate results from a randomized experiment (which provides the causal benchmark estimate), and the contexts and conditions under which these methods work in practice. This article presents a coherent theory of the design and implementation of WSCs for evaluating NE methods. It introduces and identifies the multiple purposes of WSCs, required design components, common threats to validity, design variants, and causal estimands of interest in WSCs. It highlights two general approaches for empirical evaluations of methods in field settings, WSC designs with independent and dependent benchmark and NE arms. This article highlights advantages and disadvantages for each approach, and conditions and contexts under which each approach is optimal for addressing methodological questions.

Contraceptive discontinuation and switching among couples receiving integrated HIV and family planning services in Lusaka, Zambia

PubMed Central

Haddad, Lisa; Wall, Kristin M; Vwalika, Bellington; Htee Khu, Naw; Brill, Ilene; Kilembe, William; Stephenson, Rob; Chomba, Elwyn; Vwalika, Cheswa; Tichacek, Amanda; Allen, Susan

2014-01-01

Objective To describe predictors of contraceptive method discontinuation and switching behaviors among HIV positive couples receiving couples' voluntary HIV counseling and testing services in Lusaka, Zambia. Design Couples were randomized in a factorial design to two family planning educational intervention videos, received comprehensive family planning services, and were assessed every 3-months for contraceptive initiation, discontinuation and switching. Methods We modeled factors associated with contraceptive method upgrading and downgrading via multivariate Andersen-Gill models. Results Most women continued the initial method selected after randomization. The highest rates of discontinuation/switching were observed for injectable contraceptive and intrauterine device users. Time to discontinuing the more effective contraceptive methods or downgrading to oral contraceptives or condoms was associated with the women's younger age, desire for more children within the next year, heavy menstrual bleeding, bleeding between periods, and cystitis/dysuria. Health concerns among women about contraceptive implants and male partners not wanting more children were associated with upgrading from oral contraceptives or condoms. HIV status of the woman or the couple was not predictive of switching or stopping. Conclusions We found complicated patterns of contraceptive use. The predictors of contraception switching indicate that interventions targeted to younger couples that address common contraception-related misconceptions could improve effective family planning utilization. We recommend these findings be used to increase the uptake and continuation of contraception, especially long acting reversible contraceptive (LARC) methods, and that fertility-goal based, LARC-focused family planning be offered as an integral part of HIV prevention services. PMID:24088689

Multiple types of synchronization analysis for discontinuous Cohen-Grossberg neural networks with time-varying delays.

PubMed

Li, Jiarong; Jiang, Haijun; Hu, Cheng; Yu, Zhiyong

2018-03-01

This paper is devoted to the exponential synchronization, finite time synchronization, and fixed-time synchronization of Cohen-Grossberg neural networks (CGNNs) with discontinuous activations and time-varying delays. Discontinuous feedback controller and Novel adaptive feedback controller are designed to realize global exponential synchronization, finite time synchronization and fixed-time synchronization by adjusting the values of the parameters ω in the controller. Furthermore, the settling time of the fixed-time synchronization derived in this paper is less conservative and more accurate. Finally, some numerical examples are provided to show the effectiveness and flexibility of the results derived in this paper. Copyright © 2018 Elsevier Ltd. All rights reserved.

Discontinuation of dialysis.

PubMed

Motes, C E

1989-10-01

With the evolution and recognition of a legal right to self-determination and right to privacy, it is inevitable that some competent end stage renal disease patients opt to discontinue dialysis. Although justified as a constitutional right, there are other issues that must be considered in resolving their decision to forego dialysis treatment. This article addresses pertinent moral, ethical, and legal issues pertaining to this right.

Patterns of osteoporosis treatment change and treatment discontinuation among commercial and Medicare Advantage Prescription Drug members in a national health plan.

PubMed

Xu, Yihua; Viswanathan, Hema N; Ward, Melea A; Clay, Brad; Adams, John L; Stolshek, Bradley S; Kallich, Joel D; Fine, Shari; Saag, Kenneth G

2013-02-01

Multiple treatments are available for osteoporosis; however, little is known about treatment change patterns and associated factors. Osteoporosis treatment change patterns, discontinuation and factors associated with treatment change in members of a large national health plan were examined. A retrospective cohort study was conducted in 7315 commercial and 34 146 Medicare Advantage Prescription Drug (MAPD) members newly initiated on an osteoporosis medication between 2006 and 2008. Osteoporosis treatment change, discontinuation and re-initiation patterns were assessed. Multivariate logistic regression was used to examine factors associated with treatment change. Commercial and MAPD members were assessed separately because of differences in demographics and insurance benefits. Approximately 12% of members had a change in index therapy within 12 months. Almost 60% of members discontinued the index medication at least once, based on a 90-day refill gap. Over 40% of members discontinued all osteoporosis medications by the end of 12 months post-index. Among MAPD and commercial members, women and those with risedronate, ibandronate or calcitonin at index, index therapy in 2008 and an osteoporosis diagnosis were more likely to have a treatment change while members with health plans other than health maintenance organizations and generic alendronate at index were less likely to have a treatment change. Osteoporosis treatment change occurred in approximately 12% of members, while a greater proportion of members discontinued treatment completely within 12 months. Member characteristics may be used to predict therapy change for evaluation and quality initiatives within a health plan. © 2011 Blackwell Publishing Ltd.

Hierarchy of sedimentary discontinuity surfaces and condensed beds from the middle Paleozoic of eastern North America: Implications for cratonic sequence stratigraphy

USGS Publications Warehouse

McLaughlin, P.I.; Brett, Carlton E.; Wilson, M.A.

2008-01-01

Sedimentological analyses of middle Paleozoic epeiric sea successions in North America suggest a hierarchy of discontinuity surfaces and condensed beds of increasing complexity. Simple firmgrounds and hardgrounds, which are comparatively ephemeral features, form the base of the hierarchy. Composite hardgrounds, reworked concretions, authigenic mineral crusts and monomictic intraformational conglomerates indicate more complex histories. Polymictic intraformational conglomerates, ironstones and phosphorites form the most complex discontinuity surfaces and condensed beds. Complexity of discontinuities is closely linked to depositional environments duration of sediment starvation and degree of reworking which in turn show a relationship to stratigraphic cyclicity. A model of cratonic sequence stratigraphy is generated by combining data on the complexity and lateral distribution of discontinuities in the context of facies successions. Lowstand, early transgressive and late transgressive systems tracts are representative of sea-level rise. Early and late transgressive systems tracts are separated by the maximum starvation surface (typically a polymictic intraformational conglomerate or condensed phosphorite), deposited during the peak rate of sea-level rise. Conversely the maximum flooding surface, representing the highest stand of sea level, is marked by little to no break in sedimentation. The highstand and falling stage systems tracts are deposited during relative sea-level fall. They are separated by the forced-regression surface, a thin discontinuity surface or condensed bed developed during the most rapid rate of sea-level fall. The lowest stand of sea level is marked by the sequence boundary. In subaerially exposed areas it is occasionally modified as a rockground or composite hardground.

On one-sided filters for spectral Fourier approximations of discontinuous functions

NASA Technical Reports Server (NTRS)

Wei, Cai; Gottlieb, David; Shu, Chi-Wang

1991-01-01

The existence of one-sided filters, for spectral Fourier approximations of discontinuous functions, which can recover spectral accuracy up to discontinuity from one side, was proved. A least square procedure was also used to construct such a filter and test it on several discontinuous functions numerically.

A Hyperspherical Adaptive Sparse-Grid Method for High-Dimensional Discontinuity Detection

DOE PAGES

Zhang, Guannan; Webster, Clayton G.; Gunzburger, Max D.; ...

2015-06-24

This study proposes and analyzes a hyperspherical adaptive hierarchical sparse-grid method for detecting jump discontinuities of functions in high-dimensional spaces. The method is motivated by the theoretical and computational inefficiencies of well-known adaptive sparse-grid methods for discontinuity detection. Our novel approach constructs a function representation of the discontinuity hypersurface of an N-dimensional discontinuous quantity of interest, by virtue of a hyperspherical transformation. Then, a sparse-grid approximation of the transformed function is built in the hyperspherical coordinate system, whose value at each point is estimated by solving a one-dimensional discontinuity detection problem. Due to the smoothness of the hypersurface, the newmore » technique can identify jump discontinuities with significantly reduced computational cost, compared to existing methods. In addition, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. Rigorous complexity analyses of the new method are provided as are several numerical examples that illustrate the effectiveness of the approach.« less

Numerical Simulations of Shock Wave Refraction at Inclined Gas Contact Discontinuity

ERIC Educational Resources Information Center

Bulat, Pavel V.; Volkov, Konstantin N.

2016-01-01

When a shock wave interacts with a contact discontinuity, there may appear a reflected rarefaction wave, a deflected contact discontinuity and a refracted supersonic shock. The numerical simulation of shock wave refraction at a plane contact discontinuity separating gases with different densities is performed. Euler equations describing inviscid…

Predictors of adalimumab drug survival in psoriasis differ by reason for discontinuation: long-term results from the Bio-CAPTURE registry.

PubMed

van den Reek, J M P A; Tummers, M; Zweegers, J; Seyger, M M B; van Lümig, P P M; Driessen, R J B; van de Kerkhof, P C M; Kievit, W; de Jong, E M G J

2015-03-01

Drug survival is an indicator for treatment success; insight in predictors associated with drug survival is important. To analyse the long-term drug survival for adalimumab in patients with psoriasis treated in daily practice and (II) to identify predictors of prolonged drug survival for adalimumab split for different reasons of discontinuation. Data were extracted from a prospective psoriasis cohort and analysed using Kaplan-Meier survival curves split for reasons of discontinuation. Baseline predictors associated with longer drug survival were identified using multivariate Cox-regression analysis. One hundred and sixteen patients were included with a total of 208 patient-years. Overall drug survival was 76% after 1 year and 52% after 4.5 years. In patients who stopped due to ineffectiveness, longer drug survival was associated with the absence of specific comorbidities (P = 0.03). In patients who stopped due to side-effects, longer drug survival was associated with male gender (P = 0.02). Predictors of adalimumab drug survival in psoriasis differ by reason for discontinuation. Strong, specific predictors can lead to patient-tailored treatment. © 2014 European Academy of Dermatology and Venereology.

Waiting-time distributions of magnetic discontinuities: clustering or Poisson process?

PubMed

Greco, A; Matthaeus, W H; Servidio, S; Dmitruk, P

2009-10-01

Using solar wind data from the Advanced Composition Explorer spacecraft, with the support of Hall magnetohydrodynamic simulations, the waiting-time distributions of magnetic discontinuities have been analyzed. A possible phenomenon of clusterization of these discontinuities is studied in detail. We perform a local Poisson's analysis in order to establish if these intermittent events are randomly distributed or not. Possible implications about the nature of solar wind discontinuities are discussed.

Waiting-time distributions of magnetic discontinuities: Clustering or Poisson process?

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

Greco, A.; Matthaeus, W. H.; Servidio, S.

2009-10-15

Using solar wind data from the Advanced Composition Explorer spacecraft, with the support of Hall magnetohydrodynamic simulations, the waiting-time distributions of magnetic discontinuities have been analyzed. A possible phenomenon of clusterization of these discontinuities is studied in detail. We perform a local Poisson's analysis in order to establish if these intermittent events are randomly distributed or not. Possible implications about the nature of solar wind discontinuities are discussed.

Financial catastrophe, treatment discontinuation and death associated with surgically operable cancer in South-East Asia: Results from the ACTION Study.

PubMed

Jan, Stephen; Kimman, Merel; Peters, Sanne A E; Woodward, Mark

2015-06-01

This study assessed the extent to which individuals with surgically operable cancer in Southeast Asia experience financially catastrophic out-of-pocket costs, discontinuation of treatment, or death. The ACTION study is a prospective, 8-country, cohort study of adult patients recruited consecutively with an initial diagnosis of cancer from public and private hospitals. Participants were interviewed at baseline and 3 months. In this paper, we identified 4,584 participants in whom surgery was indicated in initial treatment plans and assessed the following competing outcomes: death, financial catastrophe (out-of-pocket costs of >30% of annual household income), treatment discontinuation, and hospitalization without financial catastrophe incurred. We then analyzed a range of predictors using a multinomial regression model. Of the participants, 72% were female and 44% had health insurance at baseline. At 3 months, 31% of participants incurred financial catastrophe, 8% had died, 23% had discontinued treatment, and 38% were hospitalized but avoided financial catastrophe. Health insurance status was found to be associated with lower odds of treatment discontinuation (odds ratio [OR], 0.60; 95% CI, 0.47-0.77) relative to hospitalization without financial catastrophe. Women had greater odds of financial catastrophe than men (OR, 1.35; 95% CI, 1.05-1.74), whereas lower socioeconomic status (range of indicators) was generally found to be associated with higher odds of death, treatment discontinuation, and financial catastrophe. Priority should be given to measures such as programs to extend social health insurance to offset the out-of-pocket costs associated with surgery for cancer faced in particular by women, the uninsured, and individuals of low socioeconomic status in Southeast Asia. Copyright © 2015 Elsevier Inc. All rights reserved.

Hales discontinuity beneath India: selective appearance and a case for systematic modeling

NASA Astrophysics Data System (ADS)

Mitra, S.; Chaudhury, J.

2016-12-01

Hales discontinuity was first reported in Lake Superior at depth of 80-90 km, characterized by an increase in P-wave velocity from 8.05 to 8.45 km/s. Subsequent, worldwide studies have observed this discontinuity beneath selected continental regions and Pacific Ocean, with depth varying from 40 to 115 km. The cause for the absence of observable signal corresponding to the Hales discontinuity beneath a number of seismic stations and the large depth variation of the discontinuity are poorly understood. In the Indian subcontinent, the Hales discontinuity has been selectively imaged beneath the Southern Granulite Terrain, Eastern Dharwar, Bastar and Aravalli Cratons. These studies used low frequency P-wave receiver functions (P-RFs) to show that the Hales discontinuity corresponds to a PHs phase arriving between 7.5 and 11 s. A few studies have forwarded modeled this phase to demonstrate that this arrival is distinct from Moho reverberations and corresponds to a depth range of 75-90 km. However, these studies have ignored the effect of mid-crustal discontinuity, which had been observed in P-RF inverted crustal models beneath these stations, and its first reverberation coincide with the reported PHs. We demonstrate through forward modeling that the observed Hales discontinuity PHs can be matched by the PpPs from mid-crustal discontinuity beneath the cratons, with the exception of Hyderabad (HYB), where this discontinuity was reported to be deepest at 90 km. We perform joint inversion of the HYB P-RFs with Rayleigh wave dispersion to obtain a 32 km thick two layer crust, and Hales discontinuity at a depth of 108±2 km, with 4% increase in S-wave velocity from 4.6 to 4.8 km/s. Several mechanisms have been proposed to explain this velocity discontinuity, which include transition from spinel to garnet peridotite or changes in cation partitioning in olivine. We intend to evaluate the velocity increase based on thermoelasticity data of minerals constituting peridotite.

Discontinuities, cross-scale patterns, and the organization of ecosystems

USGS Publications Warehouse

Nash, Kirsty L.; Allen, Craig R.; Angeler, David G.; Barichievy, Chris; Eason, Tarsha; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Knutson, Melinda; Nelson, R. John; Nystrom, Magnus; Stow, Craig A.; Sandstrom, Shana M.

2014-01-01

Ecological structures and processes occur at specific spatiotemporal scales, and interactions that occur across multiple scales mediate scale-specific (e.g., individual, community, local, or regional) responses to disturbance. Despite the importance of scale, explicitly incorporating a multi-scale perspective into research and management actions remains a challenge. The discontinuity hypothesis provides a fertile avenue for addressing this problem by linking measureable proxies to inherent scales of structure within ecosystems. Here we outline the conceptual framework underlying discontinuities and review the evidence supporting the discontinuity hypothesis in ecological systems. Next we explore the utility of this approach for understanding cross-scale patterns and the organization of ecosystems by describing recent advances for examining nonlinear responses to disturbance and phenomena such as extinctions, invasions, and resilience. To stimulate new research, we present methods for performing discontinuity analysis, detail outstanding knowledge gaps, and discuss potential approaches for addressing these gaps.

A non-conventional discontinuous Lagrangian for viscous flow

PubMed Central

Marner, F.

2017-01-01

Drawing an analogy with quantum mechanics, a new Lagrangian is proposed for a variational formulation of the Navier–Stokes equations which to-date has remained elusive. A key feature is that the resulting Lagrangian is discontinuous in nature, posing additional challenges apropos the mathematical treatment of the related variational problem, all of which are resolvable. In addition to extending Lagrange's formalism to problems involving discontinuous behaviour, it is demonstrated that the associated equations of motion can self-consistently be interpreted within the framework of thermodynamics beyond local equilibrium, with the limiting case recovering the classical Navier–Stokes equations. Perspectives for applying the new formalism to discontinuous physical phenomena such as phase and grain boundaries, shock waves and flame fronts are provided. PMID:28386415

A non-conventional discontinuous Lagrangian for viscous flow.

PubMed

Scholle, M; Marner, F

2017-02-01

Drawing an analogy with quantum mechanics, a new Lagrangian is proposed for a variational formulation of the Navier-Stokes equations which to-date has remained elusive. A key feature is that the resulting Lagrangian is discontinuous in nature, posing additional challenges apropos the mathematical treatment of the related variational problem, all of which are resolvable. In addition to extending Lagrange's formalism to problems involving discontinuous behaviour, it is demonstrated that the associated equations of motion can self-consistently be interpreted within the framework of thermodynamics beyond local equilibrium, with the limiting case recovering the classical Navier-Stokes equations. Perspectives for applying the new formalism to discontinuous physical phenomena such as phase and grain boundaries, shock waves and flame fronts are provided.

The structure of rotational discontinuities. [in solar wind

NASA Technical Reports Server (NTRS)

Neugebauer, M.

1989-01-01

This study examines the structures of a set of rotational discontinuities detected in the solar wind by the ISEE-3 spacecraft. It is found that the complexity of the structure increases as the angle theta between the propagation vector k and the magnetic field decreases. For rotational discontinuities that propagate at a large angle to the field with an ion (left-hand) sense of rotation, the magnetic hodograms tend to be flattened, in agreement with prior numerical simulations. When theta is large, angular 'overshoots' are often observed at one or both ends of the discontinuity. When the propagation is nearly parallel to the field (when theta is small), many different types of structure are seen, ranging from straight lines, to S-shaped curves, to complex, disorganized shapes.

News and views in discontinuous phase transitions

NASA Astrophysics Data System (ADS)

Nagler, Jan

2014-03-01

Recent progress in the theory of discontinuous percolation allow us to better understand the the sudden emergence of large-scale connectedness both in networked systems and on the lattice. We analytically study mechanisms for the amplification of critical fluctuations at the phase transition point, non-self-averaging and power law fluctuations. A single event analysis allow to establish criteria for discontinuous percolation transitions, even on the high-dimensional lattice. Some applications such as salad bowl percolation, and inverse fragmentation are discussed.

Designing Studies That Would Address the Multilayered Nature of Health Care

PubMed Central

Pennell, Michael; Rhoda, Dale; Hade, Erinn M.; Paskett, Electra D.

2010-01-01

We review design and analytic methods available for multilevel interventions in cancer research with particular attention to study design, sample size requirements, and potential to provide statistical evidence for causal inference. The most appropriate methods will depend on the stage of development of the research and whether randomization is possible. Early on, fractional factorial designs may be used to screen intervention components, particularly when randomization of individuals is possible. Quasi-experimental designs, including time-series and multiple baseline designs, can be useful once the intervention is designed because they require few sites and can provide the preliminary evidence to plan efficacy studies. In efficacy and effectiveness studies, group-randomized trials are preferred when randomization is possible and regression discontinuity designs are preferred otherwise if assignment based on a quantitative score is possible. Quasi-experimental designs may be used, especially when combined with recent developments in analytic methods to reduce bias in effect estimates. PMID:20386057

Impact of a transition to more restrictive drug formulary on therapy discontinuation and medication adherence.

PubMed

Shirneshan, E; Kyrychenko, P; Matlin, O S; Avila, J P; Brennan, T A; Shrank, W H

2016-02-01

There is conclusive evidence demonstrating that formulary restrictions are associated with reduced utilization and pharmacy spending of the restricted drugs. However, prior efforts to implement restrictive formularies have been associated with inconsistent rates of therapy discontinuation and mixed impacts on adherence to therapy. Also, the impact of transferring patients from an already restrictive formulary to a more aggressive model has not been previously examined. This study evaluated the impact of implementation of a more restrictive formulary on therapy disruption, adherence rates, pharmacy costs and generic utilization among patients with common chronic conditions. In 2014, CVS Health implemented Value Formulary (VF), a restrictive benefit design with the aim of reducing spending while preserving access to and adherence to essential therapy, was used. A retrospective cohort study was conducted to assess changes in therapy disruption rates, pharmacy costs and generic dispensing rate (GDR) (for continuers) and medication adherence (for initiators) following the implementation of VF. The study group was selected from members of three existing employer clients transitioned from standard formulary (SF) to VF on January 2014. The control population was a matched group of six employers with the same preperiod formulary structure, business unit, adherence programmes and patient out-of-pocket cost as the study group. The control group retained SF in 2014. To assess therapy disruption after VF implementation, we categorized patients by their subsequent medication use into three groups: (i) therapy stopped, (ii) therapy continued and (iii) therapy switched. Medication adherence was measured as monthly proportion of days covered (PDC). Pharmacy cost and GDR were measured per utilizer per month (PUPM). Rates of therapy disruption in study and control groups were compared using the chi-square test. Differences in monthly PDC between matched groups were evaluated using

Contribution of strong discontinuities to the power spectrum of the solar wind.

PubMed

Borovsky, Joseph E

2010-09-10

Eight and a half years of magnetic field measurements (2(22) samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the "inertial subrange" with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this "inertial subrange." Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

Suicide Risk at Young Adulthood: Continuities and Discontinuities From Adolescence

PubMed Central

Hooven, Carole; Snedker, Karen A.; Thompson, Elaine Adams

2011-01-01

Young adult suicide is an important social problem, yet little is known about how risk for young adult suicide develops from earlier life stages. In this study the authors report on 759 young adults who were potential high school dropouts as youth. At both adolescence and young adulthood, measures of suicide risk status and related suicide risk factors are collected. With a two-by-two classification on the basis of suicide risk status at both adolescence and young adulthood, the authors distinguish four mutually exclusive groups reflecting suicide risk at two life stages. Using ANOVA and logistic regression, both adolescent and young adult suicide risk factors are identified, with evidence of similarity between risk factors at adolescence and at young adulthood, for both individual-level and social-context factors. There is also support for both continuity and discontinuity of adolescent suicide risk. Implications for social policy are discussed. PMID:23129876

7 CFR 247.17 - Notification of discontinuance of participant.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Section 247.17 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.17... effective date of discontinuance. (b) What must a local agency do if it has to discontinue a participant...

7 CFR 247.17 - Notification of discontinuance of participant.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Section 247.17 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.17... effective date of discontinuance. (b) What must a local agency do if it has to discontinue a participant...

The derivative discontinuity of the exchange-correlation functional.

PubMed

Mori-Sánchez, Paula; Cohen, Aron J

2014-07-28

The derivative discontinuity is a key concept in electronic structure theory in general and density functional theory in particular. The electronic energy of a quantum system exhibits derivative discontinuities with respect to different degrees of freedom that are a consequence of the integer nature of electrons. The classical understanding refers to the derivative discontinuity of the total energy as a function of the total number of electrons (N), but it can also manifest at constant N. Examples are shown in models including several hydrogen systems with varying numbers of electrons or nuclear charge (Z), as well as the 1-dimensional Hubbard model (1DHM). Two sides of the problem are investigated: first, the failure of currently used approximate exchange-correlation functionals in DFT and, second, the importance of the derivative discontinuity in the exact electronic structure of molecules, as revealed by full configuration interaction (FCI). Currently, all approximate functionals, including hybrids, miss the derivative discontinuity, leading to basic errors that can be seen in many ways: from the complete failure to give the total energy of H2 and H2(+), to the missing gap in Mott insulators such as stretched H2 and the thermodynamic limit of the 1DHM, or a qualitatively incorrect density in the HZ molecule with two electrons and incorrect electron transfer processes. Description of the exact particle behaviour of electrons is emphasised, which is key to many important physical processes in real systems, especially those involving electron transfer, and offers a challenge for the development of new exchange-correlation functionals.

Porter's generic strategies, discontinuous environments, and performance: a longitudinal study of changing strategies in the hospital industry.

PubMed

Lamont, B T; Marlin, D; Hoffman, J J

1993-12-01

Changes in generic strategies in response to discontinuous environments have been relatively ignored in the management literature. This study reports an examination of the relationships between Porter's (1980) generic strategies, discontinuous environments, and performance. Archival data for 1984 and 1988 were collected for 172 acute care hospitals in Florida in order to test these relationships. To examine fully the performance impact of changes in strategy in a discontinuous environment, a longitudinal research design that identified a firm's strategy at two points in time, 1984 and 1988, was used. Results indicate that firms with a proper strategy environment fit performed the highest, firms that did not change their strategy had no change in performance, and firms that changed their strategy toward a proper strategy environment showed an increase in performance. Findings support the notion that hospitals with appropriate strategy-environment combinations will exhibit higher performance.

Safety of ipsapirone treatment compared with lorazepam: discontinuation effects.

PubMed Central

Busto, U E; Naranjo, C A; Bremner, K E; Peachey, J E; Bologa, M

1998-01-01

OBJECTIVE: To determine discontinuation effects of ipsapirone, a novel azapirone and partial 5-HTIA agonist that has anxiolytic effects clinically and has not caused dependence or withdrawal symptoms in animals, and to compare these effects with those of the benzodiazepine lorazepam, owing to concern about dependence or withdrawal symptoms following use of these drugs. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: Outpatient and inpatient treatment. PARTICIPANTS: Sixty-five healthy male volunteers who had experience with sedative-hypnotics or anxiolytics and did not meet DSM-III-R criteria for abuse or dependence. INTERVENTIONS: Participants were randomized to receive ipsapirone 15 mg per day (n = 17), ipsapirone 22.5 mg per day (n = 16), lorazepam 3 mg per day (n = 16), or placebo (n = 16) as outpatients for 36 days (treatment) followed by single-blind placebo as inpatients for 3 days and as outpatients for 6 days (withdrawal). OUTCOME MEASURES: Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Scale (HAM-D), Spielberger State Anxiety Scale, Sleep Quality Questionnaire, General Symptom Checklist, self-rated intoxication, Clinical Institute Withdrawal Assessment--Benzodiazepines (CIWA-Benzo), psychomotor testing and urine drug screen. RESULTS: Only 45 subjects completed the study; discontinuation rates did not significantly differ among treatment groups. At day 39, fewer and less severe symptoms (e.g., insomnia and fatigue) were found on the CIWA-Benzo scale after treatment with ipsapirone or placebo than after treatment with lorazepam (p < 0.05). Subjects reported longer sleep latency and poorer sleep quality after receiving lorazepam than after receiving ipsapirone or placebo. Scores on the HAM-D, Spielberger State Anxiety and HAM-A scales did not change from baseline. CONCLUSIONS: Withdrawal symptoms were detected after discontinuation of therapeutic doses of lorazepam. Significantly fewer symptoms were observed after

[Social representations of TB patients on treatment discontinuation].

PubMed

Chirinos, Narda Estela Calsin; Meirelles, Betina Hörner Schlindwein; Bousfield, Andréa Barbará Silva

2015-01-01

To understand the social representations of people with TB who discontinued treatment in a Program of Tuberculosis Control. a descriptive study of qualitative approach conducted in the city of Lima, Peru. Data were collected from October to November 2012, through semi-structured interviews with eight individuals and the method used was thematic content analysis. The categories led to the construction of the social representation that the disease and the treatment bring suffering. This representation influences non-adherence to treatment and may increase the rates of treatment discontinuation. Educational strategies linked to social interaction processes, to subjectivity and to the patient context are needed to reduce the rates of discontinuation of tuberculosis treatment, relapses and multi-drug resistance. The evaluations point to new challenges that must be faced to achieve the Millennium Development Goals.

Stress Regression Analysis of Asphalt Concrete Deck Pavement Based on Orthogonal Experimental Design and Interlayer Contact

NASA Astrophysics Data System (ADS)

Wang, Xuntao; Feng, Jianhu; Wang, Hu; Hong, Shidi; Zheng, Supei

2018-03-01

A three-dimensional finite element box girder bridge and its asphalt concrete deck pavement were established by ANSYS software, and the interlayer bonding condition of asphalt concrete deck pavement was assumed to be contact bonding condition. Orthogonal experimental design is used to arrange the testing plans of material parameters, and an evaluation of the effect of different material parameters in the mechanical response of asphalt concrete surface layer was conducted by multiple linear regression model and using the results from the finite element analysis. Results indicated that stress regression equations can well predict the stress of the asphalt concrete surface layer, and elastic modulus of waterproof layer has a significant influence on stress values of asphalt concrete surface layer.

Comparison of continuous and discontinuous collisional bumpers: Dimensionally scaled impact experiments into single wire meshes

NASA Technical Reports Server (NTRS)

Hoerz, Friedrich; Cintala, Mark; See, Thomas; Bernhard, Ronald; Cardenas, Frank; Davidson, William; Haynes, Jerry

1992-01-01

An experimental inquiry into the utility of discontinuous bumpers was conducted to investigate the collisional outcomes of impacts into single grid-like targets and to compare the results with more traditional bumper designs that employ continuous sheet stock. We performed some 35 experiments using 6.3 and 3.2 mm diameter spherical soda-lime glass projectiles at low velocities (less than 2.5 km/s) and 13 at velocities between 5 and 6 km/s, using 3.2 mm spheres only. The thrust of the experiments related to the characterization of collisional fragments as a function of target thickness or areal shield mass of both bumper designs. The primary product of these experiments was witness plates that record the resulting population of collisional fragments. Substantial interpretive and predictive insights into bumper performance were obtained. All qualitative observations (on the witness plates) and detailed measurements of displaced masses seem simply and consistently related only to bumper mass available for interaction with the impactor. This renders the grid bumper into the superior shield design. These findings present evidence that discontinuous bumpers are a viable concept for collisional shields, possibly superior to continuous geometries.

Forensic Excavation of Rock Masses: A Technique to Investigate Discontinuity Persistence

NASA Astrophysics Data System (ADS)

Shang, J.; Hencher, S. R.; West, L. J.; Handley, K.

2017-11-01

True persistence of rock discontinuities (areas with insignificant tensile strength) is an important factor controlling the engineering behaviour of fractured rock masses, but is extremely difficult to quantify using current geological survey methodologies, even where there is good rock exposure. Trace length as measured in the field or using remote measurement devices is actually only broadly indicative of persistence for rock engineering practice and numerical modelling. Visible traces of discontinuities are treated as if they were open fractures within rock mass classifications, despite many such traces being non-persistent and actually retaining considerable strength. The common assumption of 100% persistence, based on trace length, is generally extremely conservative in terms of strength and stiffness, but not always so and may lead to a wrong prediction of failure mechanism or of excavatability. Assuming full persistence would give hopelessly incorrect predictions of hydraulic conductivity. A new technique termed forensic excavation of rock masses is introduced, as a procedure for directly investigating discontinuity persistence. This technique involves non-explosive excavation of rock masses by injecting an expansive chemical splitter along incipient discontinuities. On expansion, the splitter causes the incipient traces to open as true joints. Experiments are described in which near-planar rock discontinuities, through siltstone and sandstone, were opened up by injecting the splitter into holes drilled along the lines of visible traces of the discontinuities in the laboratory and in the field. Once exposed the surfaces were examined to investigate the pre-existing persistence characteristics of the incipient discontinuities. One conclusion from this study is that visible trace length of a discontinuity can be a poor indicator of true persistence (defined for a fracture area with negligible tensile strength). An observation from this series of experiments

Automatic extraction of discontinuity orientation from rock mass surface 3D point cloud

NASA Astrophysics Data System (ADS)

Chen, Jianqin; Zhu, Hehua; Li, Xiaojun

2016-10-01

This paper presents a new method for extracting discontinuity orientation automatically from rock mass surface 3D point cloud. The proposed method consists of four steps: (1) automatic grouping of discontinuity sets using an improved K-means clustering method, (2) discontinuity segmentation and optimization, (3) discontinuity plane fitting using Random Sample Consensus (RANSAC) method, and (4) coordinate transformation of discontinuity plane. The method is first validated by the point cloud of a small piece of a rock slope acquired by photogrammetry. The extracted discontinuity orientations are compared with measured ones in the field. Then it is applied to a publicly available LiDAR data of a road cut rock slope at Rockbench repository. The extracted discontinuity orientations are compared with the method proposed by Riquelme et al. (2014). The results show that the presented method is reliable and of high accuracy, and can meet the engineering needs.

21 CFR 314.91 - Obtaining a reduction in the discontinuance notification period.

Code of Federal Regulations, 2013 CFR

2013-04-01

... AND HUMAN SERVICES (CONTINUED) DRUGS FOR HUMAN USE APPLICATIONS FOR FDA APPROVAL TO MARKET A NEW DRUG... manufacturer of certain products notifies FDA that it will discontinue manufacturing the product. The discontinuance notification period ends when manufacturing ceases. (b) When can FDA reduce the discontinuance...

21 CFR 314.91 - Obtaining a reduction in the discontinuance notification period.

Code of Federal Regulations, 2011 CFR

2011-04-01

... AND HUMAN SERVICES (CONTINUED) DRUGS FOR HUMAN USE APPLICATIONS FOR FDA APPROVAL TO MARKET A NEW DRUG... manufacturer of certain products notifies FDA that it will discontinue manufacturing the product. The discontinuance notification period ends when manufacturing ceases. (b) When can FDA reduce the discontinuance...

21 CFR 314.91 - Obtaining a reduction in the discontinuance notification period.

Code of Federal Regulations, 2012 CFR

2012-04-01

... AND HUMAN SERVICES (CONTINUED) DRUGS FOR HUMAN USE APPLICATIONS FOR FDA APPROVAL TO MARKET A NEW DRUG... manufacturer of certain products notifies FDA that it will discontinue manufacturing the product. The discontinuance notification period ends when manufacturing ceases. (b) When can FDA reduce the discontinuance...

21 CFR 314.91 - Obtaining a reduction in the discontinuance notification period.

Code of Federal Regulations, 2010 CFR

2010-04-01

... AND HUMAN SERVICES (CONTINUED) DRUGS FOR HUMAN USE APPLICATIONS FOR FDA APPROVAL TO MARKET A NEW DRUG... manufacturer of certain products notifies FDA that it will discontinue manufacturing the product. The discontinuance notification period ends when manufacturing ceases. (b) When can FDA reduce the discontinuance...

Discontinuities in the shallow Martian crust at Lunae, Syria, and Sinai Plana

USGS Publications Warehouse

Davis, P.A.; Golombek, M.P.

1990-01-01

Detailed photoclinometric profiles across 125 erosional features and 141 grabens in the western equatorial region of Mars indicate the presence of three discontinuities within the shallow crust, at depths of 0.3, 0.6 km, 1 km, and 2-3 km. The shallowest discontinuity corresponds to thickness estimates for the ridged plains unit in this region, and thus the discontinuity probably is the contact between a sequence of layered rock making up this unit and the underlying megaregolith. The 1-km discontinuity is reflected in the base levels of erosion of all the features studied, and it may correspond to the base of the proposed layer of ground ice. Model calculations show that graben-bounding faults consistently intersect at the mechanical discontinuity at about 1 km depth. This discontinuity may represent an interface between ice-laden and dry regolith, ice-laden and water-laden regolith, or pristine and cemented regolith. A correlation between wall valley head depth and local thickness of the faulted layer suggests that the 1-km discontinuity also controlled the depth of the heads of sapping canyons. The third discontinuity, at a depth of 2-3 km, corresponds to the proposed base of the Martian megaregolith and is probably the interface between overlying, ejected breccia and in situ, fractured basement rocks. -from Authors

Severe disease exacerbations in patients with multiple sclerosis after discontinuing fingolimod.

PubMed

Członkowska, Anna; Smoliński, Łukasz; Litwin, Tomasz

Discontinuation of fingolimod in patients with multiple sclerosis (MS) can lead to disease reactivation. In this review, we describe cases of severe exacerbations in patients with MS following discontinuation of fingolimod, including three cases from our center. We consider potential mechanisms of disease reactivation after cessation of fingolimod, and the evidence supporting this rebound effect. We conclude that discontinuation of fingolimod results in the return of disease activity, which then leads to severe exacerbations (i.e., rebounds) in a clinically significant proportion of patients. Lastly, we consider disease-modifying treatment options for patients who discontinue fingolimod. Copyright © 2017. Published by Elsevier Urban & Partner Sp. z o.o.

High-Order Residual-Distribution Schemes for Discontinuous Problems on Irregular Triangular Grids

NASA Technical Reports Server (NTRS)

Mazaheri, Alireza; Nishikawa, Hiroaki

2016-01-01

In this paper, we develop second- and third-order non-oscillatory shock-capturing hyperbolic residual distribution schemes for irregular triangular grids, extending our second- and third-order schemes to discontinuous problems. We present extended first-order N- and Rusanov-scheme formulations for hyperbolic advection-diffusion system, and demonstrate that the hyperbolic diffusion term does not affect the solution of inviscid problems for vanishingly small viscous coefficient. We then propose second- and third-order blended hyperbolic residual-distribution schemes with the extended first-order Rusanov-scheme. We show that these proposed schemes are extremely accurate in predicting non-oscillatory solutions for discontinuous problems. We also propose a characteristics-based nonlinear wave sensor for accurately detecting shocks, compression, and expansion regions. Using this proposed sensor, we demonstrate that the developed hyperbolic blended schemes do not produce entropy-violating solutions (unphysical stocks). We then verify the design order of accuracy of these blended schemes on irregular triangular grids.

Technological Discontinuities and Organizational Environments.

ERIC Educational Resources Information Center

Tushman, Michael L.; Anderson, Philip

1986-01-01

Technological effects on environmental conditions are analyzed using longitudinal data from the minicomputer, cement, and airline industries. Technology evolves through periods of incremental change punctuated by breakthroughs that enhance or destroy the competence of firms. Competence-destroying discontinuities increase environmental turbulence;…

Determinants for drug survival of methotrexate in patients with psoriasis, split according to different reasons for discontinuation: results of the prospective MTX-CAPTURE.

PubMed

Otero, M E; van den Reek, J M; Seyger, M M; van de Kerkhof, P C; Kievit, W; de Jong, E M

2017-08-01

As methotrexate (MTX) is a widely used treatment for psoriasis, it is important to gain insight into the reasons for the discontinuation of MTX and to understand the determinants for drug survival. To describe 5-year drug survival for MTX in patients with psoriasis, split according to different reasons for discontinuation, and to identify the determinants for drug survival. Data were extracted from a prospective psoriasis registry of patients treated with MTX (MTX-CAPTURE). Drug survival was analysed using Kaplan-Meier estimates and the determinants for discontinuation were analysed using Cox regression analysis. Analyses were split according to the reason for discontinuation: side-effects or ineffectiveness. We included 85 patients treated with MTX, with a maximum treatment duration of 5·2 years. The overall drug survival rates were 63%, 30% and 15% after 1, 3 and 5 years, respectively. The median survival was 1·8 years. Overall, 55 patients (65%) discontinued MTX for the following reasons: side-effects (35%), ineffectiveness (26%), combination of side-effects and ineffectiveness (13%), other reasons (16%) and 11% were lost to follow-up. The most reported side-effects were gastrointestinal symptoms, despite the use of folic acid in 99% of patients. Based on univariate analysis, a high Psoriasis Area and Severity Index score and a high score on the visual analogue scale for disease severity at baseline were possible determinants for a short drug survival. Drug survival of MTX was low with 15% of patients 'on drug' after 5 years. Side-effects alone or in combination with inadequate disease control were more important in the context of treatment discontinuation than inadequate disease control alone. © 2017 British Association of Dermatologists.

Reciprocity principle for scattered fields from discontinuities in waveguides.

PubMed

Pau, Annamaria; Capecchi, Danilo; Vestroni, Fabrizio

2015-01-01

This study investigates the scattering of guided waves from a discontinuity exploiting the principle of reciprocity in elastodynamics, written in a form that applies to waveguides. The coefficients of reflection and transmission for an arbitrary mode can be derived as long as the principle of reciprocity is satisfied at the discontinuity. Two elastodynamic states are related by the reciprocity. One is the response of the waveguide in the presence of the discontinuity, with the scattered fields expressed as a superposition of wave modes. The other state is the response of the waveguide in the absence of the discontinuity oscillating according to an arbitrary mode. The semi-analytical finite element method is applied to derive the needed dispersion relation and wave mode shapes. An application to a solid cylinder with a symmetric double change of cross-section is presented. This model is assumed to be representative of a damaged rod. The coefficients of reflection and transmission of longitudinal waves are investigated for selected values of notch length and varying depth. Copyright © 2014 Elsevier B.V. All rights reserved.

Global synchronization in finite time for fractional-order neural networks with discontinuous activations and time delays.

PubMed

Peng, Xiao; Wu, Huaiqin; Song, Ka; Shi, Jiaxin

2017-10-01

This paper is concerned with the global Mittag-Leffler synchronization and the synchronization in finite time for fractional-order neural networks (FNNs) with discontinuous activations and time delays. Firstly, the properties with respect to Mittag-Leffler convergence and convergence in finite time, which play a critical role in the investigation of the global synchronization of FNNs, are developed, respectively. Secondly, the novel state-feedback controller, which includes time delays and discontinuous factors, is designed to realize the synchronization goal. By applying the fractional differential inclusion theory, inequality analysis technique and the proposed convergence properties, the sufficient conditions to achieve the global Mittag-Leffler synchronization and the synchronization in finite time are addressed in terms of linear matrix inequalities (LMIs). In addition, the upper bound of the setting time of the global synchronization in finite time is explicitly evaluated. Finally, two examples are given to demonstrate the validity of the proposed design method and theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

EVALUATING DISCONTINUITIES IN COMPLEX SYSTEMS: TOWARD QUANTITATIVE MEASURE OF RESILIENCE

EPA Science Inventory

The textural discontinuity hypothesis (TDH) is based on the observation that animal body mass distributions exhibit discontinuities that may reflect the texture of the landscape available for exploitation. This idea has been extended to other complex systems, hinting that the ide...

Drug Discontinuation Effects Are Part of the Pharmacology of a Drug

PubMed Central

2011-01-01

Most reviews of drug withdrawal effects focus on drugs of potential abuse such as opioids, benzodiazepines, etc. Abrupt discontinuation of many other drugs used in medicine cause withdrawal syndromes, some of which can be fatal. Discontinuation of a number of cardiovascular drugs can increase risk of cardiovascular events above that of people not taking these drugs. These include β-adrenergic receptor antagonists, aspirin, HMG-CoA reductase inhibitors (statins), and heparin. Rebound hypertension occurs after abrupt cessation of many antihypertensive drugs. The possibility of discontinuation syndromes has usually been neglected until adverse clinical events force them to be noticed. Attention to the possibility of drug discontinuation effects is an important part of drug safety evaluation. PMID:21849624

Transition density of one-dimensional diffusion with discontinuous drift

NASA Technical Reports Server (NTRS)

Zhang, Weijian

1990-01-01

The transition density of a one-dimensional diffusion process with a discontinuous drift coefficient is studied. A probabilistic representation of the transition density is given, illustrating the close connections between discontinuities of the drift and Brownian local times. In addition, some explicit results are obtained based on the trivariate density of Brownian motion, its occupation, and local times.

The 520 km Discontinuity: No Longer Just the Middle Child of the Transition Zone

NASA Astrophysics Data System (ADS)

Houser, C.; Williams, Q.

2008-12-01

The 520 km discontinuity is more difficult to image and changes character laterally more relative to its siblings the 410 km and 660 km discontinuities. The 520 km discontinuity is thought to result from the phase change of β-spinel to γ-spinel, a transition which has a smaller impedance contrast than the olivine to β-spinel or the γ-spinel to perovskite and periclase transitions that are associated with the 410 km and 660 km discontinuities, respectively. In addition, there are gradual phase changes occurring in the pyroxene component of the mantle between the 410 km and 660 km discontinuity which complicate imaging and interpretation of the 520 km discontinuity. The best global coverage of discontinuity depth comes from the stacking of SS precursors, seismic phases that bounce off the discontinuities and arrive as precursors to the main SS phase. A recent study by Houser et al. (2008) contains the largest compilation of SS precursor measurements. However, since the 520 km discontinuity is not ubiquitously observed, its characteristics were not addressed. Here, we examine the geographic distribution (which is global, but not even) of high quality 520 km discontinuity measurements derived from precursors. The principal result is that the depth of the 520 km discontinuity has a higher correlation with tomographically-imaged high and low seismic velocities than either the 410 km or 660 km discontinuities. This stronger temperature sensitivity is in accord with determinations of the Clapeyron slopes of the differing transitions. Furthermore, this correlation is observed in a wide range of tectonic environments, and the prospect thus exists that the 520 km discontinuity will, where it is observed, provide a tighter bound on temperature within the transition zone than either of the other major discontinuities. Furthermore, improved constraints on the temperature distribution at depth may produce improved insight into the relative roles of thermal and compositional

Targeted Business Incentives and Local Labor Markets

ERIC Educational Resources Information Center

Freedman, Matthew

2013-01-01

This paper uses a regression discontinuity design to examine the effects of geographically targeted business incentives on local labor markets. Unlike elsewhere in the United States, enterprise zone (EZ) designations in Texas are determined in part by a cutoff rule based on census block group poverty rates. Exploiting this discontinuity as a…

Bounded extremum seeking with discontinuous dithers

DOE PAGES

Scheinker, Alexander; Scheinker, David

2016-03-21

The analysis of discontinuous extremum seeking (ES) controllers, e.g. those applicable to digital systems, has historically been more complicated than that of continuous controllers. We establish a simple and general extension of a recently developed bounded form of ES to a general class of oscillatory functions, including functions discontinuous with respect to time, such as triangle or square waves with dead time. We establish our main results by combining a novel idea for oscillatory control with an extension of functional analytic techniques originally utilized by Kurzweil, Jarnik, Sussmann, and Liu in the late 80s and early 90s and recently studiedmore » by Durr et al. Lastly, we demonstrate the value of the result with an application to inverter switching control.« less

A Leap-Frog Discontinuous Galerkin Method for the Time-Domain Maxwell's Equations in Metamaterials

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

Li, J., Waters, J. W., Machorro, E. A.

2012-06-01

Numerical simulation of metamaterials play a very important role in the design of invisibility cloak, and sub-wavelength imaging. In this paper, we propose a leap-frog discontinuous Galerkin method to solve the time-dependent Maxwell’s equations in metamaterials. Conditional stability and error estimates are proved for the scheme. The proposed algorithm is implemented and numerical results supporting the analysis are provided.

Reconstructing Buildings with Discontinuities and Roof Overhangs from Oblique Aerial Imagery

NASA Astrophysics Data System (ADS)

Frommholz, D.; Linkiewicz, M.; Meissner, H.; Dahlke, D.

2017-05-01

This paper proposes a two-stage method for the reconstruction of city buildings with discontinuities and roof overhangs from oriented nadir and oblique aerial images. To model the structures the input data is transformed into a dense point cloud, segmented and filtered with a modified marching cubes algorithm to reduce the positional noise. Assuming a monolithic building the remaining vertices are initially projected onto a 2D grid and passed to RANSAC-based regression and topology analysis to geometrically determine finite wall, ground and roof planes. If this should fail due to the presence of discontinuities the regression will be repeated on a 3D level by traversing voxels within the regularly subdivided bounding box of the building point set. For each cube a planar piece of the current surface is approximated and expanded. The resulting segments get mutually intersected yielding both topological and geometrical nodes and edges. These entities will be eliminated if their distance-based affiliation to the defining point sets is violated leaving a consistent building hull including its structural breaks. To add the roof overhangs the computed polygonal meshes are projected onto the digital surface model derived from the point cloud. Their shapes are offset equally along the edge normals with subpixel accuracy by detecting the zero-crossings of the second-order directional derivative in the gradient direction of the height bitmap and translated back into world space to become a component of the building. As soon as the reconstructed objects are finished the aerial images are further used to generate a compact texture atlas for visualization purposes. An optimized atlas bitmap is generated that allows perspectivecorrect multi-source texture mapping without prior rectification involving a partially parallel placement algorithm. Moreover, the texture atlases undergo object-based image analysis (OBIA) to detect window areas which get reintegrated into the building

Effect of Discontinuities and Penetrations on the Shielding Efficacy of High Temperature Superconducting Magnetic Shields

NASA Astrophysics Data System (ADS)

Hatwar, R.; Kvitkovic, J.; Herman, C.; Pamidi, S.

2015-12-01

High Temperature Superconducting (HTS) materials have been demonstrated to be suitable for applications in shielding of both DC and AC magnetic fields. Magnetic shielding is required for protecting sensitive instrumentation from external magnetic fields and for preventing the stray magnetic fields produced by high power density equipment from affecting neighbouring devices. HTS shields have high current densities at relatively high operating temperatures (40-77 K) and can be easily fabricated using commercial HTS conductor. High current densities in HTS materials allow design and fabrication of magnetic shields that are lighter and can be incorporated into the body and skin of high power density devices. HTS shields are particularly attractive for HTS devices because a single cryogenic system can be used for cooling the device and the associated shield. Typical power devices need penetrations for power and signal cabling and the penetrations create discontinuities in HTS shields. Hence it is important to assess the effect of the necessary discontinuities on the efficacy of the shields and the design modifications necessary to accommodate the penetrations.

Introduction to the use of regression models in epidemiology.

PubMed

Bender, Ralf

2009-01-01

Regression modeling is one of the most important statistical techniques used in analytical epidemiology. By means of regression models the effect of one or several explanatory variables (e.g., exposures, subject characteristics, risk factors) on a response variable such as mortality or cancer can be investigated. From multiple regression models, adjusted effect estimates can be obtained that take the effect of potential confounders into account. Regression methods can be applied in all epidemiologic study designs so that they represent a universal tool for data analysis in epidemiology. Different kinds of regression models have been developed in dependence on the measurement scale of the response variable and the study design. The most important methods are linear regression for continuous outcomes, logistic regression for binary outcomes, Cox regression for time-to-event data, and Poisson regression for frequencies and rates. This chapter provides a nontechnical introduction to these regression models with illustrating examples from cancer research.

41 CFR 101-39.105 - Discontinuance or curtailment of service.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., AND MOTOR VEHICLES 39-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.1-Establishment, Modification, and Discontinuance of Interagency Fleet Management Systems § 101-39.105 Discontinuance or curtailment of service. (a... efficiencies are realized from the operation of any fleet management system, the Administrator, GSA, will...

Fatigue Behavior of HY-130 Steel Weldments Containing Fabrication Discontinuities.

DTIC Science & Technology

1985-04-18

discontinuities to solutions for elliptical discontinuities. One such approach has been formalized in the ASME Section XI Boiler and Pressure Vessel Code [1... Boiler and Pressure Vessel Code , Section XI, "Rules for Inservice Inspection of Nuclear Reactor Coolant Systems," American Society of Mechanical

Adaptive Discontinuous Evolution Galerkin Method for Dry Atmospheric Flow

DTIC Science & Technology

2013-04-02

standard one-dimensional approximate Riemann solver used for the flux integration demonstrate better stability, accuracy as well as reliability of the...discontinuous evolution Galerkin method for dry atmospheric convection. Comparisons with the standard one-dimensional approximate Riemann solver used...instead of a standard one- dimensional approximate Riemann solver , the flux integration within the discontinuous Galerkin method is now realized by

Discontinuous Spectral Difference Method for Conservation Laws on Unstructured Grids

NASA Technical Reports Server (NTRS)

Liu, Yen; Vinokur, Marcel; Wang, Z. J.

2004-01-01

A new, high-order, conservative, and efficient method for conservation laws on unstructured grids is developed. The concept of discontinuous and high-order local representations to achieve conservation and high accuracy is utilized in a manner similar to the Discontinuous Galerkin (DG) and the Spectral Volume (SV) methods, but while these methods are based on the integrated forms of the equations, the new method is based on the differential form to attain a simpler formulation and higher efficiency. A discussion on the Discontinuous Spectral Difference (SD) Method, locations of the unknowns and flux points and numerical results are also presented.

Safety and Benefit of Discontinuing Statin Therapy in the Setting of Advanced, Life-Limiting Illness

PubMed Central

Kutner, Jean S.; Blatchford, Patrick J.; Taylor, Don H.; Ritchie, Christine S.; Bull, Janet H.; Fairclough, Diane L.; Hanson, Laura C.; LeBlanc, Thomas W.; Samsa, Greg P.; Wolf, Steven; Aziz, Noreen M.; Currow, David C.; Ferrell, Betty; Wagner-Johnston, Nina; Zafar, S. Yousuf; Cleary, James F.; Dev, Sandesh; Goode, Patricia S.; Kamal, Arif H.; Kassner, Cordt; Kvale, Elizabeth A.; McCallum, Janelle G.; Ogunseitan, Adeboye B.; Pantilat, Steven Z.; Portenoy, Russell K.; Prince-Paul, Maryjo; Sloan, Jeff A.; Swetz, Keith M.; Von Gunten, Charles F.; Abernethy, Amy P.

2015-01-01

IMPORTANCE For patients with limited prognosis, some medication risks may outweigh the benefits, particularly when benefits take years to accrue; statins are one example. Data are lacking regarding the risks and benefits of discontinuing statin therapy for patients with limited life expectancy. OBJECTIVE To evaluate the safety, clinical, and cost impact of discontinuing statin medications for patients in the palliative care setting. DESIGN, SETTING, AND PARTICIPANTS This was a multicenter, parallel-group, unblinded, pragmatic clinical trial. Eligibility included adults with an estimated life expectancy of between 1 month and 1 year, statin therapy for 3 months or more for primary or secondary prevention of cardiovascular disease, recent deterioration in functional status, and no recent active cardiovascular disease. Participants were randomized to either discontinue or continue statin therapy and were monitored monthly for up to 1 year. The study was conducted from June 3, 2011, to May 2, 2013. All analyses were performed using an intent-to-treat approach. INTERVENTIONS Statin therapy was withdrawn from eligible patients who were randomized to the discontinuation group. Patients in the continuation group continued to receive statins. MAIN OUTCOMES AND MEASURES Outcomes included death within 60 days (primary outcome), survival, cardiovascular events, performance status, quality of life (QOL), symptoms, number of nonstatin medications, and cost savings. RESULTS A total of 381 patients were enrolled; 189 of these were randomized to discontinue statins, and 192 were randomized to continue therapy. Mean (SD) age was 74.1 (11.6) years, 22.0% of the participants were cognitively impaired, and 48.8% had cancer. The proportion of participants in the discontinuation vs continuation groups who died within 60 days was not significantly different (23.8% vs 20.3%; 90% CI, −3.5% to 10.5%; P = .36) and did not meet the noninferiority end point. Total QOL was better for the group

How do horizontal, frictional discontinuities affect reverse fault-propagation folding?

NASA Astrophysics Data System (ADS)

Bonanno, Emanuele; Bonini, Lorenzo; Basili, Roberto; Toscani, Giovanni; Seno, Silvio

2017-09-01

The development of new reverse faults and related folds is strongly controlled by the mechanical characteristics of the host rocks. In this study we analyze the impact of a specific kind of anisotropy, i.e. thin mechanical and frictional discontinuities, in affecting the development of reverse faults and of the associated folds using physical scaled models. We perform analog modeling introducing one or two initially horizontal, thin discontinuities above an initially blind fault dipping at 30° in one case, and 45° in another, and then compare the results with those obtained from a fully isotropic model. The experimental results show that the occurrence of thin discontinuities affects both the development and the propagation of new faults and the shape of the associated folds. New faults 1) accelerate or decelerate their propagation depending on the location of the tips with respect to the discontinuities, 2) cross the discontinuities at a characteristic angle (∼90°), and 3) produce folds with different shapes, resulting not only from the dip of the new faults but also from their non-linear propagation history. Our results may have direct impact on future kinematic models, especially those aimed to reconstruct the tectonic history of faults that developed in layered rocks or in regions affected by pre-existing faults.

Wave field features of shallow vertical discontinuity and their application in non-destructive detection

USGS Publications Warehouse

Liu, J.; Xia, J.; Luo, Y.; Chen, C.; Li, X.; Huang, Y.

2007-01-01

The geotechnical integrity of critical infrastructure can be seriously compromised by the presence of fractures or crevices. Non-destructive techniques to accurately detect fractures in critical infrastructure such as dams and highways could be of significant benefit to the geotechnical industry. This paper investigates the application of shallow seismic and georadar methods to the detection of a vertical discontinuity using numerical simulations. The objective is to address the kinematical analysis of a vertical discontinuity, determine the resulting wave field characteristics, and provide the basis for determining the existence of vertical discontinuities based on the recorded signals. Simulation results demonstrate that: (1) A reflection from a vertical discontinuity produces a hyperbolic feature on a seismic or georadar profile; (2) In order for a reflection from a vertical discontinuity to be produced, a reflecting horizon below the discontinuity must exist, the offset between source and receiver (x0) must be non-zero, on the same side of the vertical discontinuity; (3) The range of distances from the vertical discontinuity where a reflection event is observed is proportional to its length and to x0; (4) Should the vertical crevice (or fracture) pass through a reflecting horizon, dual hyperbolic features can be observed on the records, and this can be used as a determining factor that the vertical crevice passes through the interface; and (5) diffractions from the edges of the discontinuity can be recorded with relatively smaller amplitude than reflections and their ranges are not constrained by the length of discontinuity. If the length of discontinuity is short enough, diffractions are the dominant feature. Real-world examples show that the shallow seismic reflection method and the georadar method are capable of recording the hyperbolic feature, which can be interpreted as vertical discontinuity. Thus, these methods show some promise as effective non

47 CFR 27.66 - Discontinuance, reduction, or impairment of service.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Discontinuance, reduction, or impairment of..., reduction, or impairment of service. (a) Involuntary act. If the service provided by a fixed common carrier... notify the Commission, in writing, as to the reasons for discontinuance, reduction, or impairment of...

46 CFR 550.507 - Postponement, discontinuance, or suspension of action.

Code of Federal Regulations, 2010 CFR

2010-10-01

... action. The Commission may, on its own motion or upon petition, postpone, discontinue, or suspend any and... 46 Shipping 9 2010-10-01 2010-10-01 false Postponement, discontinuance, or suspension of action. 550.507 Section 550.507 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AND ACTIONS TO ADDRESS...

46 CFR 550.507 - Postponement, discontinuance, or suspension of action.

Code of Federal Regulations, 2011 CFR

2011-10-01

... action. The Commission may, on its own motion or upon petition, postpone, discontinue, or suspend any and... 46 Shipping 9 2011-10-01 2011-10-01 false Postponement, discontinuance, or suspension of action. 550.507 Section 550.507 Shipping FEDERAL MARITIME COMMISSION REGULATIONS AND ACTIONS TO ADDRESS...

Hierarchical Adaptive Regression Kernels for Regression with Functional Predictors.

PubMed

Woodard, Dawn B; Crainiceanu, Ciprian; Ruppert, David

2013-01-01

We propose a new method for regression using a parsimonious and scientifically interpretable representation of functional predictors. Our approach is designed for data that exhibit features such as spikes, dips, and plateaus whose frequency, location, size, and shape varies stochastically across subjects. We propose Bayesian inference of the joint functional and exposure models, and give a method for efficient computation. We contrast our approach with existing state-of-the-art methods for regression with functional predictors, and show that our method is more effective and efficient for data that include features occurring at varying locations. We apply our methodology to a large and complex dataset from the Sleep Heart Health Study, to quantify the association between sleep characteristics and health outcomes. Software and technical appendices are provided in online supplemental materials.

Father's Labour Migration and Children's School Discontinuation in Rural Mozambique.

PubMed

Yabiku, Scott T; Agadjanian, Victor

2017-08-01

We examine how the discontinuation of schooling among left-behind children is related to multiple dimensions of male labor migration: the accumulation of migration experience, the timing of these migration experiences in the child's life course, and the economic success of the migration. Our setting is rural southern Mozambique, an impoverished area with massive male labor out-migration. Results show that fathers' economically successful labor migration is more beneficial for children's schooling than unsuccessful migration or non-migration. There are large differences, however, by gender: compared to sons of non-migrants, sons of migrant fathers (regardless of migration success) have lower rates of school discontinuation, while daughters of migrant fathers have rates of school discontinuation no different than daughters of non-migrants. Furthermore, accumulated labor migration across the child's life course is beneficial for boys' schooling, but not girls'. Remittances sent in the past year reduce the rate of discontinuation for sons, but not daughters.

Longitudinal studies of botulinum toxin in cervical dystonia: Why do patients discontinue therapy?

PubMed

Jinnah, H A; Comella, Cynthia L; Perlmutter, Joel; Lungu, Codrin; Hallett, Mark

2018-06-01

Numerous studies have established botulinum toxin (BoNT) to be safe and effective for the treatment of cervical dystonia (CD). Despite its well-documented efficacy, there has been growing awareness that a significant proportion of CD patients discontinue therapy. The reasons for discontinuation are only partly understood. This summary describes longitudinal studies that provided information regarding the proportions of patients discontinuing BoNT therapy, and the reasons for discontinuing therapy. The data come predominantly from un-blinded long-term follow-up studies, registry studies, and patient-based surveys. All types of longitudinal studies provide strong evidence that BoNT is both safe and effective in the treatment of CD for many years. Overall, approximately one third of CD patients discontinue BoNT. The most common reason for discontinuing therapy is lack of benefit, often described as primary or secondary non-response. The apparent lack of response is only rarely related to true immune-mediated resistance to BoNT. Other reasons for discontinuing include side effects, inconvenience, cost, or other reasons. Although BoNT is safe and effective in the treatment of the majority of patients with CD, approximately one third discontinue. The increasing awareness of a significant proportion of patients who discontinue should encourage further efforts to optimize administration of BoNT, to improve BoNT preparations to extend duration or reduce side effects, to develop add-on therapies that may mitigate swings in symptom severity, or develop entirely novel treatment approaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ensuring the Quality of Evidence: Using the Best Design to Answer Health IT Questions.

PubMed

Weir, Charlene R

2016-01-01

The quality of logic in a research design determines the value of the results and our confidence regarding the validity of the findings. The purpose of this contribution is to review the principles of research design as they apply to research and evaluation in health IT. We review the architecture of research design, the definitions of cause, sources of bias and confounds, and the importance of measurement as related to the various types of health IT questions. The goal is to provide practitioners a roadmap for making decisions for their own specific study. The contribution is organized around the Threats to Validity taxonomy and explains how different design models address these threats through the use of blocking, factorial design, control groups and time series analysis. The contribution discusses randomized experiments, and includes regression discontinuity designs and various quasi-experimental designs with a special emphasis on how to improve pre/post designs. At the end, general recommendations are provided for improving weaker designs and general research procedures.

Mingus Discontinuous Multiphysics

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

Pat Notz, Dan Turner

Mingus provides hybrid coupled local/non-local mechanics analysis capabilities that extend several traditional methods to applications with inherent discontinuities. Its primary features include adaptations of solid mechanics, fluid dynamics and digital image correlation that naturally accommodate dijointed data or irregular solution fields by assimilating a variety of discretizations (such as control volume finite elements, peridynamics and meshless control point clouds). The goal of this software is to provide an analysis framework form multiphysics engineering problems with an integrated image correlation capability that can be used for experimental validation and model

21 CFR 1301.52 - Termination of registration; transfer of registration; distribution upon discontinuance of business.

Code of Federal Regulations, 2010 CFR

2010-04-01

... discontinues business or professional practice. Any registrant who ceases legal existence or discontinues... registration; distribution upon discontinuance of business. 1301.52 Section 1301.52 Food and Drugs DRUG... of registration; transfer of registration; distribution upon discontinuance of business. (a) Except...

Design, fabrication and test of block 4 design solar cell modules. Part 2: Residential module

NASA Technical Reports Server (NTRS)

Jester, T. L.

1982-01-01

Design, fabrication and test of the Block IV residential load module are reported. Design changes from the proposed module design through three iterations to the discontinuance of testing are outlined.

Evaluation of occupational health interventions using a randomized controlled trial: challenges and alternative research designs.

PubMed

Schelvis, Roosmarijn M C; Oude Hengel, Karen M; Burdorf, Alex; Blatter, Birgitte M; Strijk, Jorien E; van der Beek, Allard J

2015-09-01

Occupational health researchers regularly conduct evaluative intervention research for which a randomized controlled trial (RCT) may not be the most appropriate design (eg, effects of policy measures, organizational interventions on work schedules). This article demonstrates the appropriateness of alternative designs for the evaluation of occupational health interventions, which permit causal inferences, formulated along two study design approaches: experimental (stepped-wedge) and observational (propensity scores, instrumental variables, multiple baseline design, interrupted time series, difference-in-difference, and regression discontinuity). For each design, the unique characteristics are presented including the advantages and disadvantages compared to the RCT, illustrated by empirical examples in occupational health. This overview shows that several appropriate alternatives for the RCT design are feasible and available, which may provide sufficiently strong evidence to guide decisions on implementation of interventions in workplaces. Researchers are encouraged to continue exploring these designs and thus contribute to evidence-based occupational health.

Diabetes insipidus after discontinuation of vasopressin infusion for septic shock.

PubMed

Rana, H; Ferguson, N; Dicpinigaitis, P V

2018-04-01

Despite widespread use of vasopressin for the treatment of septic shock, few cases of diabetes insipidus (DI) following its discontinuation have been reported. A 54-year-old man presented with pneumonia progressing to septic shock, requiring norepinephrine and vasopressin for refractory hypotension. After clinical improvement, the patient on 3 separate occasions developed polyuria and severe hypernatremia upon discontinuation of vasopressin, with prompt recovery upon its resumption. Occurrence of DI upon discontinuation of vasopressin infusion appears to be rare, but incidence may be underestimated due to a paucity of published reports. Actual incidence and underlying mechanism of this phenomenon remain to be elucidated. © 2017 John Wiley & Sons Ltd.

Establishing a Mathematical Equations and Improving the Production of L-tert-Leucine by Uniform Design and Regression Analysis.

PubMed

Jiang, Wei; Xu, Chao-Zhen; Jiang, Si-Zhi; Zhang, Tang-Duo; Wang, Shi-Zhen; Fang, Bai-Shan

2017-04-01

L-tert-Leucine (L-Tle) and its derivatives are extensively used as crucial building blocks for chiral auxiliaries, pharmaceutically active ingredients, and ligands. Combining with formate dehydrogenase (FDH) for regenerating the expensive coenzyme NADH, leucine dehydrogenase (LeuDH) is continually used for synthesizing L-Tle from α-keto acid. A multilevel factorial experimental design was executed for research of this system. In this work, an efficient optimization method for improving the productivity of L-Tle was developed. And the mathematical model between different fermentation conditions and L-Tle yield was also determined in the form of the equation by using uniform design and regression analysis. The multivariate regression equation was conveniently implemented in water, with a space time yield of 505.9 g L -1  day -1 and an enantiomeric excess value of >99 %. These results demonstrated that this method might become an ideal protocol for industrial production of chiral compounds and unnatural amino acids such as chiral drug intermediates.

Discontinuous pore fluid distribution under microgravity--KC-135 flight investigations

NASA Technical Reports Server (NTRS)

Reddi, Lakshmi N.; Xiao, Ming; Steinberg, Susan L.

2005-01-01

Designing a reliable plant growth system for crop production in space requires the understanding of pore fluid distribution in porous media under microgravity. The objective of this experimental investigation, which was conducted aboard NASA KC-135 reduced gravity flight, is to study possible particle separation and the distribution of discontinuous wetting fluid in porous media under microgravity. KC-135 aircraft provided gravity conditions of 1, 1.8, and 10(-2) g. Glass beads of a known size distribution were used as porous media; and Hexadecane, a petroleum compound immiscible with and lighter than water, was used as wetting fluid at residual saturation. Nitrogen freezer was used to solidify the discontinuous Hexadecane ganglia in glass beads to preserve the ganglia size changes during different gravity conditions, so that the blob-size distributions (BSDs) could be measured after flight. It was concluded from this study that microgravity has little effect on the size distribution of pore fluid blobs corresponding to residual saturation of wetting fluids in porous media. The blobs showed no noticeable breakup or coalescence during microgravity. However, based on the increase in bulk volume of samples due to particle separation under microgravity, groups of particles, within which pore fluid blobs were encapsulated, appeared to have rearranged themselves under microgravity.

The Morphosyntax of Discontinuous Exponence

ERIC Educational Resources Information Center

Campbell, Amy Melissa

2012-01-01

This thesis offers a systematic treatment of discontinuous exponence, a pattern of inflection in which a single feature or a set of features bundled in syntax is expressed by multiple, distinct morphemes. This pattern is interesting and theoretically relevant because it represents a deviation from the expected one-to-one relationship between…

Heat exchanger containing a component capable of discontinuous movement

DOEpatents

Wilson, David Gordon

2001-04-17

Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices.

Heat exchanger containing a component capable of discontinuous movement

DOEpatents

Wilson, David G.

1993-01-01

Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices.

Heat exchanger containing a component capable of discontinuous movement

DOEpatents

Wilson, David Gordon

2002-01-01

Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices.

Adherence to guidelines for creatinine and potassium monitoring and discontinuation following renin–angiotensin system blockade: a UK general practice-based cohort study

PubMed Central

Schmidt, Morten; Bhaskaran, Krishnan; Nitsch, Dorothea; Sørensen, Henrik Toft; Smeeth, Liam; Tomlinson, Laurie A

2017-01-01

Objectives To examine adherence to serum creatinine and potassium monitoring and discontinuation guidelines following initiation of treatment with ACE inhibitors (ACEI) or angiotensin receptor blockers (ARBs); and whether high-risk patients are monitored. Design A general practice-based cohort study using electronic health records from the UK Clinical Practice Research Datalink and Hospital Episode Statistics. Setting UK primary care, 2004–2014. Subjects 223 814 new ACEI/ARB users. Main outcome measures Proportion of patients with renal function monitoring before and after ACEI/ARB initiation; creatinine increase ≥30% or potassium levels >6 mmol/L at first follow-up monitoring; and treatment discontinuation after such changes. Using logistic regression models, we also examined patient characteristics associated with these biochemical changes, and with follow-up monitoring within the guideline recommendation of 2 weeks after treatment initiation. Results 10% of patients had neither baseline nor follow-up monitoring of creatinine within 12 months before and 2 months after initiation of an ACEI/ARB, 28% had monitoring only at baseline, 15% only at follow-up, and 47% both at baseline and follow-up. The median period between the most recent baseline monitoring and drug initiation was 40 days (IQR 12–125 days). 34% of patients had baseline creatinine monitoring within 1 month before initiating therapy, but <10% also had the guideline-recommended follow-up test recorded within 2 weeks. Among patients experiencing a creatinine increase ≥30% (n=567, 1.2%) or potassium level >6 mmol/L (n=191, 0.4%), 80% continued treatment. Although patients with prior myocardial infarction, hypertension or baseline potassium >5 mmol/L were at high risk of ≥30% increase in creatinine after ACEI/ARB initiation, there was no evidence that they were more frequently monitored. Conclusions Only one-tenth of patients initiating ACEI/ARB therapy receive the guideline

Discontinuities in Early Development of the Understanding of Physical Causality

ERIC Educational Resources Information Center

Aschersleben, Gisa; Henning, Anne; Daum, Moritz M.

2013-01-01

Research on early physical reasoning has shown surprising discontinuities in developmental trajectories. Infants possess some skills that seem to disappear and then re-emerge in childhood. It has been suggested that prediction skills required in search tasks might cause these discontinuities (Keen, 2003). We tested 3.5- to 5-year-olds'…

A CLASS OF RECONSTRUCTED DISCONTINUOUS GALERKIN METHODS IN COMPUTATIONAL FLUID DYNAMICS

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

Hong Luo; Yidong Xia; Robert Nourgaliev

2011-05-01

A class of reconstructed discontinuous Galerkin (DG) methods is presented to solve compressible flow problems on arbitrary grids. The idea is to combine the efficiency of the reconstruction methods in finite volume methods and the accuracy of the DG methods to obtain a better numerical algorithm in computational fluid dynamics. The beauty of the resulting reconstructed discontinuous Galerkin (RDG) methods is that they provide a unified formulation for both finite volume and DG methods, and contain both classical finite volume and standard DG methods as two special cases of the RDG methods, and thus allow for a direct efficiency comparison.more » Both Green-Gauss and least-squares reconstruction methods and a least-squares recovery method are presented to obtain a quadratic polynomial representation of the underlying linear discontinuous Galerkin solution on each cell via a so-called in-cell reconstruction process. The devised in-cell reconstruction is aimed to augment the accuracy of the discontinuous Galerkin method by increasing the order of the underlying polynomial solution. These three reconstructed discontinuous Galerkin methods are used to compute a variety of compressible flow problems on arbitrary meshes to assess their accuracy. The numerical experiments demonstrate that all three reconstructed discontinuous Galerkin methods can significantly improve the accuracy of the underlying second-order DG method, although the least-squares reconstructed DG method provides the best performance in terms of both accuracy, efficiency, and robustness.« less

Seismic imaging of a mid-lithospheric discontinuity beneath Ontong Java Plateau

NASA Astrophysics Data System (ADS)

Tharimena, Saikiran; Rychert, Catherine A.; Harmon, Nicholas

2016-09-01

Ontong Java Plateau (OJP) is a huge, completely submerged volcanic edifice that is hypothesized to have formed during large plume melting events ∼90 and 120 My ago. It is currently resisting subduction into the North Solomon trench. The size and buoyancy of the plateau along with its history of plume melting and current interaction with a subduction zone are all similar to the characteristics and hypothesized mechanisms of continent formation. However, the plateau is remote, and enigmatic, and its proto-continent potential is debated. We use SS precursors to image seismic discontinuity structure beneath Ontong Java Plateau. We image a velocity increase with depth at 28 ± 4 km consistent with the Moho. In addition, we image velocity decreases at 80 ± 5 km and 282 ± 7 km depth. Discontinuities at 60-100 km depth are frequently observed both beneath the oceans and the continents. However, the discontinuity at 282 km is anomalous in comparison to surrounding oceanic regions; in the context of previous results it may suggest a thick viscous root beneath OJP. If such a root exists, then the discontinuity at 80 km bears some similarity to the mid-lithospheric discontinuities (MLDs) observed beneath continents. One possibility is that plume melting events, similar to that which formed OJP, may cause discontinuities in the MLD depth range. Plume-plate interaction could be a mechanism for MLD formation in some continents in the Archean prior to the onset of subduction.

Long-term outcomes for patients with chronic lymphocytic leukemia who discontinue ibrutinib.

PubMed

Jain, Preetesh; Thompson, Philip A; Keating, Michael; Estrov, Zeev; Ferrajoli, Alessandra; Jain, Nitin; Kantarjian, Hagop; Burger, Jan A; O'Brien, Susan; Wierda, William G

2017-06-15

Ibrutinib is a Bruton tyrosine kinase inhibitor and is approved for the treatment of patients with chronic lymphocytic leukemia (CLL) in frontline and relapsed/refractory settings. The authors previously reported poor outcomes for patients who discontinued ibrutinib; however, long-term outcomes were not reported. Data from 320 patients who received ibrutinib on clinical studies between 2010 and 2015 at The University of Texas MD Anderson Cancer Center were retrospectively analyzed. Long-term outcomes among patients with CLL after they discontinued ibrutinib were analyzed. Ninety of 320 patients (28%) who were treated on ibrutinib-based regimens discontinued ibrutinib. Of these, 80 had relapsed/refractory disease, and 10 were treatment-naive. The median time to discontinuation was 15 months (range, 1.2-54 months). After a median follow-up of 38 months after starting ibrutinib, 40 patients (44%) remained alive. Major reasons for ibrutinib discontinuation were intolerance (n = 29; 32%), miscellaneous (n = 28; 31%), progression (n = 19; 21%), and Richter transformation (RT) (n = 9; 10%). The median survival according to the reason for discontinuation was 33 months for ibrutinib intolerance, 11 months for miscellaneous causes, 16 months for progressive CLL, and 2 months for RT. Among the 19 patients who had progressive CLL, 42% responded to subsequent therapy. Ibrutinib discontinuation was observed during therapy. Patients with CLL who had disease transformation had especially poor outcomes, whereas those who developed progressive disease during ibrutinib therapy had a median survival of <1.5 years. Survival was associated with the reason for discontinuation; patients who had progressive CLL had better survival compared with those who had disease transformation. Effective salvage strategies for patients with CLL who progress on ibrutinib therapy is of critical importance. Cancer 2017;123:2268-2273. © 2017 American Cancer Society. © 2017 American Cancer Society.

Measuring Foundation School Effectiveness Using English Administrative Data, Survey Data and a Regression Discontinuity Design

ERIC Educational Resources Information Center

Allen, Rebecca

2013-01-01

Apparently sophisticated school performance measures have been used to claim that giving schools autonomy from local government control improves pupil exam performance. This paper explores the extent to which inferring causality between autonomy and pupil achievement is reasonable given that pupils are not randomly assigned to schools and schools…

Contraceptive discontinuation and switching among couples receiving integrated HIV and family planning services in Lusaka, Zambia.

PubMed

Haddad, Lisa; Wall, Kristin M; Vwalika, Bellington; Khu, Naw Htee; Brill, Ilene; Kilembe, William; Stephenson, Rob; Chomba, Elwyn; Vwalika, Cheswa; Tichacek, Amanda; Allen, Susan

2013-10-01

To describe predictors of contraceptive method discontinuation and switching behaviours among HIV-positive couples receiving couples' voluntary HIV counselling and testing services in Lusaka, Zambia. Couples were randomized in a factorial design to two-family planning educational intervention videos, received comprehensive family planning services and were assessed every 3 months for contraceptive initiation, discontinuation and switching. We modelled factors associated with contraceptive method upgrading and downgrading via multivariate Andersen-Gill models. Most women continued the initial method selected after randomization. The highest rates of discontinuation/switching were observed for injectable contraceptive and intrauterine device users. Time to discontinuing the more effective contraceptive methods or downgrading to oral contraceptives or condoms was associated with the women's younger age, desire for more children within the next year, heavy menstrual bleeding, bleeding between periods and cystitis/dysuria. Health concerns among women about contraceptive implants and male partners not wanting more children were associated with upgrading from oral contraceptives or condoms. HIV status of the woman or the couple was not predictive of switching or stopping. We found complicated patterns of contraceptive use. The predictors of contraception switching indicate that interventions targeted to younger couples that address common contraception-related misconceptions could improve effective family planning utilization. We recommend these findings be used to increase the uptake and continuation of contraception, especially long-acting reversible contraceptive (LARC) methods, and that fertility goal based, LARC-focused family planning be offered as an integral part of HIV prevention services.

Discontinuation and Nonpublication of Randomized Clinical Trials Conducted in Children

PubMed Central

Pica, Natalie

2016-01-01

BACKGROUND: Trial discontinuation and nonpublication represent potential waste in research resources and lead to compromises in medical evidence. Pediatric trials may be particularly vulnerable to these outcomes given the challenges encountered in conducting trials in children. We aimed to determine the prevalence of discontinuation and nonpublication of randomized clinical trials (RCTs) conducted in pediatric populations. METHODS: Retrospective, cross-sectional study of pediatric RCTs registered in ClinicalTrials.gov from 2008 to 2010. Data were collected from the registry and associated publications identified (final search on September 1, 2015). RESULTS: Of 559 trials, 104 (19%) were discontinued early, accounting for an estimated 8369 pediatric participants. Difficulty with patient accrual (37%) was the most commonly cited reason for discontinuation. Trials were less likely to be discontinued if they were funded by industry compared with academic institutions (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.27–0.77). Of the 455 completed trials, 136 (30%) were not published, representing 69 165 pediatric participants. Forty-two unpublished trials posted results on ClinicalTrials.gov. Trials funded by industry were more than twice as likely to result in nonpublication at 24 and 36 months (OR 2.21, 95% CI 1.35–3.64; OR 3.12, 95% CI 1.6–6.08, respectively) and had a longer mean time to publication compared with trials sponsored by academia (33 vs 24 months, P < .001). CONCLUSIONS: In this sample of pediatric RCTs, discontinuation and nonpublication were common, with thousands of children exposed to interventions that did not lead to informative or published findings. Trial funding source was an important determinant of these outcomes, with both academic and industry sponsors contributing to inefficiencies. PMID:27492817

Discontinuation and Nonpublication of Randomized Clinical Trials Conducted in Children.

PubMed

Pica, Natalie; Bourgeois, Florence

2016-09-01

Trial discontinuation and nonpublication represent potential waste in research resources and lead to compromises in medical evidence. Pediatric trials may be particularly vulnerable to these outcomes given the challenges encountered in conducting trials in children. We aimed to determine the prevalence of discontinuation and nonpublication of randomized clinical trials (RCTs) conducted in pediatric populations. Retrospective, cross-sectional study of pediatric RCTs registered in ClinicalTrials.gov from 2008 to 2010. Data were collected from the registry and associated publications identified (final search on September 1, 2015). Of 559 trials, 104 (19%) were discontinued early, accounting for an estimated 8369 pediatric participants. Difficulty with patient accrual (37%) was the most commonly cited reason for discontinuation. Trials were less likely to be discontinued if they were funded by industry compared with academic institutions (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.27-0.77). Of the 455 completed trials, 136 (30%) were not published, representing 69 165 pediatric participants. Forty-two unpublished trials posted results on ClinicalTrials.gov. Trials funded by industry were more than twice as likely to result in nonpublication at 24 and 36 months (OR 2.21, 95% CI 1.35-3.64; OR 3.12, 95% CI 1.6-6.08, respectively) and had a longer mean time to publication compared with trials sponsored by academia (33 vs 24 months, P < .001). In this sample of pediatric RCTs, discontinuation and nonpublication were common, with thousands of children exposed to interventions that did not lead to informative or published findings. Trial funding source was an important determinant of these outcomes, with both academic and industry sponsors contributing to inefficiencies. Copyright © 2016 by the American Academy of Pediatrics.

Parents’ Subjective Assessment of Effects of Antiepileptic Drug Discontinuation

PubMed Central

Kim, Gun-Ha; Byeon, Jung Hye; Eun, So-Hee; Eun, Baik-Lin

2015-01-01

Background and Purpose: Many parents express worries about potential negative side effects of antiepileptic drugs (AED) on cognition, behavior, mood, and academic achievement. We aimed to evaluate parents’ subjective feelings about cognitive or behavioral changes in their children and their quality of life after antiepileptic drug (AED) discontinuation. Methods: A modified questionnaire based on the Korean-Quality of Life in Childhood Epilepsy and the Korean-Child Behavior Checklist was answered by parents whose children were seizure-free over the course of 1 month after AED discontinuation. All children were seizure-free for at least 2 years before AED withdrawal. Results: Fifty-eight eligible patients (mean age, 14.1 ± 4.5 years) were examined. Except valproate in cognition (p = 0.03), parents did not feel significant change after discontinuation of different drugs. They felt improvement of behavior in generalized epilepsy (p = 0.04) and better quality of life in children less than 6 year of age at diagnosis of epilepsy (p = 0.02). Conclusions: We propose that factors such as earlier age at diagnosis of epilepsy or type of epilepsy might influence parents’ subjective feelings about their children’s well-being after drug discontinuation, rather than the drug itself. PMID:26157667

AED discontinuation may be dangerous for seizure-free patients.

PubMed

Schmidt, Dieter

2011-02-01

Despite its benefits, stopping antiepileptic drugs (AEDs) in seizure-free patients is associated with several risks. AED discontinuation doubles the risk of seizure recurrence for up to 2 years compared with continued treatment. On average, one in three patients has a seizure recurrence, though the range can go up to 66% (34%, range 12-66%, 95% CI: 27-43). Furthermore, the outcome of treating a seizure recurrence in patients who have been seizure-free for years is surprisingly poor in some patients. Although the long-term prognosis is not worsened by drug discontinuation, one in five patients does not re-enter remission and for some patients, it may take several years to become seizure-free again. The risk of seizure recurrence is particularly high for those with juvenile myoclonic epilepsy and symptomatic focal epilepsy, the most frequent epilepsies in adults. Seizure-recurrence may have devastating, medical, psychological and social consequences for the individual, for example injury, loss of self-esteem, unemployment and losing a driver's license. Discontinuation should be avoided in patients with a high risk of seizure recurrence. Given these risks, patients will ultimately have to decide themselves whether they wish to discontinue drug treatment after full informed consent.

Injection-Sensitive Mechanics of Hydraulic Fracture Interaction with Discontinuities

NASA Astrophysics Data System (ADS)

Chuprakov, D.; Melchaeva, O.; Prioul, R.

2014-09-01

We develop a new analytical model, called OpenT, that solves the elasticity problem of a hydraulic fracture (HF) contact with a pre-existing discontinuity natural fracture (NF) and the condition for HF re-initiation at the NF. The model also accounts for fluid penetration into the permeable NFs. For any angle of fracture intersection, the elastic problem of a blunted dislocation discontinuity is solved for the opening and sliding generated at the discontinuity. The sites and orientations of a new tensile crack nucleation are determined based on a mixed stress- and energy-criterion. In the case of tilted fracture intersection, the finite offset of the new crack initiation point along the discontinuity is computed. We show that aside from known controlling parameters such stress contrast, cohesional and frictional properties of the NFs and angle of intersection, the fluid injection parameters such as the injection rate and the fluid viscosity are of first-order in the crossing behavior. The model is compared to three independent laboratory experiments, analytical criteria of Blanton, extended Renshaw-Pollard, as well as fully coupled numerical simulations. The relative computational efficiency of OpenT model (compared to the numerical models) makes the model attractive for implementation in modern engineering tools simulating hydraulic fracture propagation in naturally fractured environments.

Hypoglycemia After Initiation of Basal Insulin in Patients with Type 2 Diabetes in the United States: Implications for Treatment Discontinuation and Healthcare Costs and Utilization.

PubMed

Dalal, Mehul R; Kazemi, Mahmood; Ye, Fen; Xie, Lin

2017-09-01

Hypoglycemia and fear of hypoglycemia may contribute to basal insulin discontinuation, poor glycemic control, and increased healthcare burden in patients with type 2 diabetes (T2D). This study aimed to determine the impact of hypoglycemia soon after basal insulin initiation on treatment discontinuation and economic outcomes in patients with T2D. Hypoglycemic events within 6 months of basal insulin initiation were identified using retrospective cohort data from patients with T2D, at least 18 years of age, initiated on basal insulin therapy in the Clinformatics™ Data Mart for Multiplan claims database from January 1, 2008, through August 31, 2012. Data were adjusted for baseline characteristics. Discontinuation was established for patients with 12-month follow-up data, while discontinuation risk was assessed in the extended analysis (6- to 24-month follow-up) by Cox regression analysis. Healthcare use and costs were determined. Of 55,608 patients, 4.5% experienced hypoglycemia within 6 months of basal insulin initiation. Patients with hypoglycemia were more likely to discontinue basal insulin within 12 months of initiation (79.0% vs. 74.2%; P < 0.001). Data, adjusted for baseline characteristics such as age, any baseline hypoglycemia, and use of oral antidiabetes drugs, showed that patients with hypoglycemia had a greater risk of discontinuation (hazard ratio 1.16; 95% confidence interval 1.03, 1.32; P = 0.0164), were more likely to have a hospitalization (41.0% vs. 24.3%; P < 0.001) or an ED visit (55.8% vs. 35.1%; P < 0.001), and had higher diabetes-related ($13,662 vs. $7506; P < 0.001) and all-cause ($30,719 vs. $19,079; P < 0.001) healthcare costs. US patients with T2D who experienced hypoglycemia within 6 months of basal insulin initiation were more likely to discontinue treatment, accompanied by a greater healthcare burden. Sanofi US, Inc.

Prescriber preference for a particular tumour necrosis factor antagonist drug and treatment discontinuation: population-based cohort

PubMed Central

Fisher, Anat; Bassett, Ken; Wright, James M; Brookhart, M Alan; Freeman, Hugh J; Dormuth, Colin R

2014-01-01

Objective To assess the effect of physician preference for a particular tumour necrosis factor α (TNF) antagonist on the risk of treatment discontinuation in rheumatoid arthritis. Design Population-based cohort study. Setting British Columbia administrative health data (inpatients, outpatients and pharmacy). Participants 2742 British Columbia residents who initiated a first course of a TNF antagonist between 2001 and December 2008, had been diagnosed with rheumatoid arthritis, and were treated by 1 of 58 medium-volume to high-volume prescribers. Independent variable A level of physician preference for the drug (higher or lower) was assigned based on preceding prescribing records of the care-providing physician. Higher preference was defined as at least 60% of TNF antagonist courses initiated in the preceding year. Sensitivity analysis was conducted with different thresholds for higher preference. Main outcome measure Drug discontinuation was defined as a drug-free interval of 180 days or switching to another TNF antagonist, anakinra, rituximab or abatacept. The risk of discontinuation was compared between different levels of physician preference using survival analysis. Results Higher preference for the prescribed TNF antagonist was associated with improved persistence with the drug (4.28 years (95% CI 3.70 to 4.90) vs 3.27 (2.84 to 3.84), with log rank test p value of 0.017). The adjusted HR for discontinuation was significantly lower in courses of drugs with higher preference (0.85 (0.76 to 0.96)). The results were robust in a sensitivity analysis. Conclusions Higher physician preference was associated with decreased risk of discontinuing TNF antagonists in patients with rheumatoid arthritis. This finding suggests that physicians who strongly prefer a specific treatment help their patients to stay on treatment for a longer duration. Similar research on other treatments is warranted. PMID:25270855

Parallel Implementation of the Discontinuous Galerkin Method

NASA Technical Reports Server (NTRS)

Baggag, Abdalkader; Atkins, Harold; Keyes, David

1999-01-01

This paper describes a parallel implementation of the discontinuous Galerkin method. Discontinuous Galerkin is a spatially compact method that retains its accuracy and robustness on non-smooth unstructured grids and is well suited for time dependent simulations. Several parallelization approaches are studied and evaluated. The most natural and symmetric of the approaches has been implemented in all object-oriented code used to simulate aeroacoustic scattering. The parallel implementation is MPI-based and has been tested on various parallel platforms such as the SGI Origin, IBM SP2, and clusters of SGI and Sun workstations. The scalability results presented for the SGI Origin show slightly superlinear speedup on a fixed-size problem due to cache effects.

Importance of Tensile Strength on the Shear Behavior of Discontinuities

NASA Astrophysics Data System (ADS)

Ghazvinian, A. H.; Azinfar, M. J.; Geranmayeh Vaneghi, R.

2012-05-01

In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

Heat exchanger containing a component capable of discontinuous movement

DOEpatents

Wilson, D.G.

1993-11-09

Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices. 11 figures.

Design Process for High Speed Civil Transport Aircraft Improved by Neural Network and Regression Methods

NASA Technical Reports Server (NTRS)

Hopkins, Dale A.

1998-01-01

A key challenge in designing the new High Speed Civil Transport (HSCT) aircraft is determining a good match between the airframe and engine. Multidisciplinary design optimization can be used to solve the problem by adjusting parameters of both the engine and the airframe. Earlier, an example problem was presented of an HSCT aircraft with four mixed-flow turbofan engines and a baseline mission to carry 305 passengers 5000 nautical miles at a cruise speed of Mach 2.4. The problem was solved by coupling NASA Lewis Research Center's design optimization testbed (COMETBOARDS) with NASA Langley Research Center's Flight Optimization System (FLOPS). The computing time expended in solving the problem was substantial, and the instability of the FLOPS analyzer at certain design points caused difficulties. In an attempt to alleviate both of these limitations, we explored the use of two approximation concepts in the design optimization process. The two concepts, which are based on neural network and linear regression approximation, provide the reanalysis capability and design sensitivity analysis information required for the optimization process. The HSCT aircraft optimization problem was solved by using three alternate approaches; that is, the original FLOPS analyzer and two approximate (derived) analyzers. The approximate analyzers were calibrated and used in three different ranges of the design variables; narrow (interpolated), standard, and wide (extrapolated).

47 CFR 63.63 - Emergency discontinuance, reduction, or impairment of service.

Code of Federal Regulations, 2010 CFR

2010-10-01

... impairment of service. 63.63 Section 63.63 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... AND IMPAIRMENT OF SERVICE BY COMMON CARRIERS; AND GRANTS OF RECOGNIZED PRIVATE OPERATING AGENCY STATUS Discontinuance, Reduction, Outage and Impairment § 63.63 Emergency discontinuance, reduction, or impairment of...

Regression analysis as a design optimization tool

NASA Technical Reports Server (NTRS)

Perley, R.

1984-01-01

The optimization concepts are described in relation to an overall design process as opposed to a detailed, part-design process where the requirements are firmly stated, the optimization criteria are well established, and a design is known to be feasible. The overall design process starts with the stated requirements. Some of the design criteria are derived directly from the requirements, but others are affected by the design concept. It is these design criteria that define the performance index, or objective function, that is to be minimized within some constraints. In general, there will be multiple objectives, some mutually exclusive, with no clear statement of their relative importance. The optimization loop that is given adjusts the design variables and analyzes the resulting design, in an iterative fashion, until the objective function is minimized within the constraints. This provides a solution, but it is only the beginning. In effect, the problem definition evolves as information is derived from the results. It becomes a learning process as we determine what the physics of the system can deliver in relation to the desirable system characteristics. As with any learning process, an interactive capability is a real attriubute for investigating the many alternatives that will be suggested as learning progresses.

The influence of patient beliefs and treatment satisfaction on the discontinuation of current first-line antiretroviral regimens.

PubMed

Casado, J L; Marín, A; Romero, V; Bañón, S; Moreno, A; Perez-Elías, M J; Moreno, S; Rodriguez-Sagrado, M A

2016-01-01

Large cohort studies have shown a high rate of first-line combination antiretroviral therapy (cART) regimen discontinuation in HIV-infected patients, attributed to characteristics of the cART regimen or toxicity. A cohort study of 274 patients receiving a first-line regimen was carried out. Patients' perceptions and beliefs prior to initiation were assessed using an attitude towards medication scale (0-15 points), and their satisfaction during therapy was assessed using an HIV treatment satisfaction questionnaire (HIVTSQ). Treatment discontinuation was defined as any switch in the cART regimen. During 474.8 person-years of follow-up, 63 (23%) patients changed their cART regimen, mainly because of toxicity/intolerance (42; 67%). The overall rate of change was 13.2 per 100 patient-years [95% confidence interval (CI) 11.1-16.4 per 100 patient-years]. An efavirenz (EFV)-based single tablet regimen showed the highest rate of adverse events (27%), but the lowest rate of change (16%; 7.44 per 100 patient-years). Cox regression revealed a decreased hazard of first regimen termination with better initial attitude towards drugs [hazard ratio (HR) 0.76; 95% CI 0.62-0.93; P < 0.01] and higher satisfaction (HR 0.94; 95% CI 0.89-0.99; P = 0.01), and an increased hazard of termination with the presence of adverse events (HR 7.7; 95% CI 2.4-11.6; P < 0.01). One-third of patients (18 of 59; 31%) with mild/moderate adverse events (which were mainly central nervous system symptoms) continued the regimen; these patients, compared with those discontinuing therapy, showed better perception of therapy (mean score 14.4 versus 12.1, respectively; P = 0.05) and greater satisfaction during therapy (mean score 50.6 versus 44.6, respectively; P = 0.04). Patients' beliefs and satisfaction with therapy influence the durability of the first antiretroviral regimen. These patient-related factors modulate the impact of mild adverse events, and could explain differences in the

Active Correction of Aperture Discontinuities-Optimized Stroke Minimization. II. Optimization for Future Missions

NASA Astrophysics Data System (ADS)

Mazoyer, J.; Pueyo, L.; N'Diaye, M.; Fogarty, K.; Zimmerman, N.; Soummer, R.; Shaklan, S.; Norman, C.

2018-01-01

High-contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. Instrumentation techniques in this field have greatly improved over the last two decades, with the development of stellar coronagraphy, in parallel with specific methods of wavefront sensing and control. Next generation space- and ground-based telescopes will enable the characterization of cold solar-system-like planets for the first time and maybe even in situ detection of bio-markers. However, the growth of primary mirror diameters, necessary for these detections, comes with an increase of their complexity (segmentation, secondary mirror features). These discontinuities in the aperture can greatly limit the performance of coronagraphic instruments. In this context, we introduced a new technique, Active Correction of Aperture Discontinuities-Optimized Stroke Minimization (ACAD-OSM), to correct for the diffractive effects of aperture discontinuities in the final image plane of a coronagraph, using deformable mirrors. In this paper, we present several tools that can be used to optimize the performance of this technique for its application to future large missions. In particular, we analyzed the influence of the deformable setup (size and separating distance) and found that there is an optimal point for this setup, optimizing the performance of the instrument in contrast and throughput while minimizing the strokes applied to the deformable mirrors. These results will help us design future coronagraphic instruments to obtain the best performance.

The effect of topography of upper-mantle discontinuities on SS precursors

NASA Astrophysics Data System (ADS)

Koroni, Maria; Trampert, Jeannot

2016-01-01

Using the spectral-element method, we explored the effect of topography of upper-mantle discontinuities on the traveltimes of SS precursors recorded on transverse component seismograms. The latter are routinely used to infer the topography of mantle transition zone discontinuities. The step from precursory traveltimes to topographic changes is mainly done using linearised ray theory, or sometimes using finite-frequency kernels. We simulated exact seismograms in 1-D and 3-D elastic models of the mantle. In a second simulation, we added topography to the discontinuities. We compared the waveforms obtained with and without topography by cross correlation of the SS precursors. Since we did not add noise, the precursors are visible in individual seismograms without the need of stacking. The resulting time anomalies were then converted into topographic variations and compared to the original topographic models. Based on the correlation between initial and inferred models, and provided that ray coverage is good, we found that linearised ray theory gives a relatively good idea on the location of the uplifts and depressions of the discontinuities. It seriously underestimates the amplitude of the topographic variations by a factor ranging between 2 and 7. Real data depend on the 3-D elastic structure and the topography. All studies to date correct for the 3-D elastic effects assuming that the traveltimes can be linearly decomposed into a structure and a discontinuity part. We found a strong non-linearity in this decomposition which cannot be modelled without a fully non-linear inversion for elastic structure and discontinuities simultaneously.

A method for modeling discontinuities in a microwave coaxial transmission line

NASA Technical Reports Server (NTRS)

Otoshi, T. Y.

1992-01-01

A method for modeling discontinuities in a coaxial transmission line is presented. The methodology involves the use of a nonlinear least-squares fit program to optimize the fit between theoretical data (from the model) and experimental data. When this method was applied to modeling discontinuities in a slightly damaged Galileo spacecraft S-band (2.295-GHz) antenna cable, excellent agreement between theory and experiment was obtained over a frequency range of 1.70-2.85 GHz. The same technique can be applied for diagnostics and locating unknown discontinuities in other types of microwave transmission lines, such as rectangular, circular, and beam waveguides.

A method for modeling discontinuities in a microwave coaxial transmission line

NASA Astrophysics Data System (ADS)

Otoshi, T. Y.

1992-08-01

A method for modeling discontinuities in a coaxial transmission line is presented. The methodology involves the use of a nonlinear least-squares fit program to optimize the fit between theoretical data (from the model) and experimental data. When this method was applied to modeling discontinuities in a slightly damaged Galileo spacecraft S-band (2.295-GHz) antenna cable, excellent agreement between theory and experiment was obtained over a frequency range of 1.70-2.85 GHz. The same technique can be applied for diagnostics and locating unknown discontinuities in other types of microwave transmission lines, such as rectangular, circular, and beam waveguides.

A hyper-spherical adaptive sparse-grid method for high-dimensional discontinuity detection

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

Zhang, Guannan; Webster, Clayton G.; Gunzburger, Max D.

This work proposes and analyzes a hyper-spherical adaptive hierarchical sparse-grid method for detecting jump discontinuities of functions in high-dimensional spaces is proposed. The method is motivated by the theoretical and computational inefficiencies of well-known adaptive sparse-grid methods for discontinuity detection. Our novel approach constructs a function representation of the discontinuity hyper-surface of an N-dimensional dis- continuous quantity of interest, by virtue of a hyper-spherical transformation. Then, a sparse-grid approximation of the transformed function is built in the hyper-spherical coordinate system, whose value at each point is estimated by solving a one-dimensional discontinuity detection problem. Due to the smoothness of themore » hyper-surface, the new technique can identify jump discontinuities with significantly reduced computational cost, compared to existing methods. Moreover, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. Rigorous error estimates and complexity analyses of the new method are provided as are several numerical examples that illustrate the effectiveness of the approach.« less

Differentiating regressed melanoma from regressed lichenoid keratosis.

PubMed

Chan, Aegean H; Shulman, Kenneth J; Lee, Bonnie A

2017-04-01

Distinguishing regressed lichen planus-like keratosis (LPLK) from regressed melanoma can be difficult on histopathologic examination, potentially resulting in mismanagement of patients. We aimed to identify histopathologic features by which regressed melanoma can be differentiated from regressed LPLK. Twenty actively inflamed LPLK, 12 LPLK with regression and 15 melanomas with regression were compared and evaluated by hematoxylin and eosin staining as well as Melan-A, microphthalmia transcription factor (MiTF) and cytokeratin (AE1/AE3) immunostaining. (1) A total of 40% of regressed melanomas showed complete or near complete loss of melanocytes within the epidermis with Melan-A and MiTF immunostaining, while 8% of regressed LPLK exhibited this finding. (2) Necrotic keratinocytes were seen in the epidermis in 33% regressed melanomas as opposed to all of the regressed LPLK. (3) A dense infiltrate of melanophages in the papillary dermis was seen in 40% of regressed melanomas, a feature not seen in regressed LPLK. In summary, our findings suggest that a complete or near complete loss of melanocytes within the epidermis strongly favors a regressed melanoma over a regressed LPLK. In addition, necrotic epidermal keratinocytes and the presence of a dense band-like distribution of dermal melanophages can be helpful in differentiating these lesions. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Speedup of minimum discontinuity phase unwrapping algorithm with a reference phase distribution

NASA Astrophysics Data System (ADS)

Liu, Yihang; Han, Yu; Li, Fengjiao; Zhang, Qican

2018-06-01

In three-dimensional (3D) shape measurement based on phase analysis, the phase analysis process usually produces a wrapped phase map ranging from - π to π with some 2 π discontinuities, and thus a phase unwrapping algorithm is necessary to recover the continuous and nature phase map from which 3D height distribution can be restored. Usually, the minimum discontinuity phase unwrapping algorithm can be used to solve many different kinds of phase unwrapping problems, but its main drawback is that it requires a large amount of computations and has low efficiency in searching for the improving loop within the phase's discontinuity area. To overcome this drawback, an improvement to speedup of the minimum discontinuity phase unwrapping algorithm by using the phase distribution on reference plane is proposed. In this improved algorithm, before the minimum discontinuity phase unwrapping algorithm is carried out to unwrap phase, an integer number K was calculated from the ratio of the wrapped phase to the nature phase on a reference plane. And then the jump counts of the unwrapped phase can be reduced by adding 2K π, so the efficiency of the minimum discontinuity phase unwrapping algorithm is significantly improved. Both simulated and experimental data results verify the feasibility of the proposed improved algorithm, and both of them clearly show that the algorithm works very well and has high efficiency.

THE FORMATION OF ROTATIONAL DISCONTINUITIES IN COMPRESSIVE THREE-DIMENSIONAL MHD TURBULENCE

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

Yang, Liping; Feng, Xueshang; Zhang, Lei

Measurements of solar wind turbulence reveal the ubiquity of discontinuities. In this study we investigate how the discontinuities, especially rotational discontinuities (RDs), are formed in MHD turbulence. In a simulation of the decaying compressive three-dimensional (3D) MHD turbulence with an imposed uniform background magnetic field, we detect RDs with sharp field rotations and little variations of magnetic field intensity, as well as mass density. At the same time, in the de Hoffman–Teller frame, the plasma velocity is nearly in agreement with the Alfvén speed, and is field-aligned on both sides of the discontinuity. We take one of the identified RDsmore » to analyze its 3D structure and temporal evolution in detail. By checking the magnetic field and plasma parameters, we find that the identified RD evolves from the steepening of the Alfvén wave with moderate amplitude, and that steepening is caused by the nonuniformity of the Alfvén speed in the ambient turbulence.« less

Discontinuous Galerkin finite element methods for radiative transfer in spherical symmetry

NASA Astrophysics Data System (ADS)

Kitzmann, D.; Bolte, J.; Patzer, A. B. C.

2016-11-01

The discontinuous Galerkin finite element method (DG-FEM) is successfully applied to treat a broad variety of transport problems numerically. In this work, we use the full capacity of the DG-FEM to solve the radiative transfer equation in spherical symmetry. We present a discontinuous Galerkin method to directly solve the spherically symmetric radiative transfer equation as a two-dimensional problem. The transport equation in spherical atmospheres is more complicated than in the plane-parallel case owing to the appearance of an additional derivative with respect to the polar angle. The DG-FEM formalism allows for the exact integration of arbitrarily complex scattering phase functions, independent of the angular mesh resolution. We show that the discontinuous Galerkin method is able to describe accurately the radiative transfer in extended atmospheres and to capture discontinuities or complex scattering behaviour which might be present in the solution of certain radiative transfer tasks and can, therefore, cause severe numerical problems for other radiative transfer solution methods.

Discontinuous categories affect information-integration but not rule-based category learning.

PubMed

Maddox, W Todd; Filoteo, J Vincent; Lauritzen, J Scott; Connally, Emily; Hejl, Kelli D

2005-07-01

Three experiments were conducted that provide a direct examination of within-category discontinuity manipulations on the implicit, procedural-based learning and the explicit, hypothesis-testing systems proposed in F. G. Ashby, L. A. Alfonso-Reese, A. U. Turken, and E. M. Waldron's (1998) competition between verbal and implicit systems model. Discontinuous categories adversely affected information-integration but not rule-based category learning. Increasing the magnitude of the discontinuity did not lead to a significant decline in performance. The distance to the bound provides a reasonable description of the generalization profile associated with the hypothesis-testing system, whereas the distance to the bound plus the distance to the trained response region provides a reasonable description of the generalization profile associated with the procedural-based learning system. These results suggest that within-category discontinuity differentially impacts information-integration but not rule-based category learning and provides information regarding the detailed processing characteristics of each category learning system. ((c) 2005 APA, all rights reserved).

Spurious Behavior of Shock-Capturing Methods: Problems Containing Stiff Source Terms and Discontinuities

NASA Technical Reports Server (NTRS)

Yee, Helen M. C.; Kotov, D. V.; Wang, Wei; Shu, Chi-Wang

2013-01-01

The goal of this paper is to relate numerical dissipations that are inherited in high order shock-capturing schemes with the onset of wrong propagation speed of discontinuities. For pointwise evaluation of the source term, previous studies indicated that the phenomenon of wrong propagation speed of discontinuities is connected with the smearing of the discontinuity caused by the discretization of the advection term. The smearing introduces a nonequilibrium state into the calculation. Thus as soon as a nonequilibrium value is introduced in this manner, the source term turns on and immediately restores equilibrium, while at the same time shifting the discontinuity to a cell boundary. The present study is to show that the degree of wrong propagation speed of discontinuities is highly dependent on the accuracy of the numerical method. The manner in which the smearing of discontinuities is contained by the numerical method and the overall amount of numerical dissipation being employed play major roles. Moreover, employing finite time steps and grid spacings that are below the standard Courant-Friedrich-Levy (CFL) limit on shockcapturing methods for compressible Euler and Navier-Stokes equations containing stiff reacting source terms and discontinuities reveals surprising counter-intuitive results. Unlike non-reacting flows, for stiff reactions with discontinuities, employing a time step and grid spacing that are below the CFL limit (based on the homogeneous part or non-reacting part of the governing equations) does not guarantee a correct solution of the chosen governing equations. Instead, depending on the numerical method, time step and grid spacing, the numerical simulation may lead to (a) the correct solution (within the truncation error of the scheme), (b) a divergent solution, (c) a wrong propagation speed of discontinuities solution or (d) other spurious solutions that are solutions of the discretized counterparts but are not solutions of the governing equations

78 FR 11733 - Georgia Southwestern Railroad, Inc.-Discontinuance of Service Exemption-in Chattahoochee, Marion...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-19

... discontinue service, not to abandon the line, trail use/rail banking and public use conditions are not... No. AB 290 (Sub-No. 344X)] Georgia Southwestern Railroad, Inc.--Discontinuance of Service Exemption...--Discontinuance of Service Exemption--in Chattahoochee, Marion, and Schley Counties, GA Central of Georgia...

Contraceptive discontinuation and pregnancy postabortion in Nepal: a longitudinal cohort study.

PubMed

Puri, Mahesh; Henderson, Jillian T; Harper, Cynthia C; Blum, Maya; Joshi, Deepak; Rocca, Corinne H

2015-04-01

To examine postabortion contraceptive discontinuation and pregnancy in Nepal, where abortion was decriminalized in 2002. We conducted an observational cohort study of 654 women obtaining abortions from four public and nongovernmental facilities in 2011. Patients completed questionnaires at their abortion visit and 6 and 12 months later. We used Cox proportional hazards models to assess contraceptive discontinuation and pregnancy by method initiated postabortion and other sociodemographic and reproductive factors. Among the 78% (508/654) of women who initiated a modern contraceptive method within 3 months postabortion, the 1-year contraceptive discontinuation rate was 62 per 100 person-years. Discontinuation was far lower among the 5% of women using long-acting reversible methods (21/100 person-years) than among those using condoms (74/100 person-years), pills (61/100 person-years) and the injectable [64/100 person-years; adjusted hazard ratio (aHR)=0.32 (0.15-0.68)]. Unmarried women and those not living with their husband experienced higher contraceptive discontinuation [aHR=2.16 (1.47-3.17)]. The 1-year pregnancy rate for all women was 9/100 person-years. Pregnancy was highest among those who initiated no modern method postabortion (13/100 person-years) and condoms (12/100 person-years), and pregnancy was lowest among users of long-acting reversible methods (3/100 person-years). The poorest women were at increased pregnancy risk [aHR=2.31 (1.32-4.10)]. Women using intrauterine devices and implants experienced greatly reduced contraceptive discontinuation and pregnancy within a year postabortion, although initiation of these long-acting methods was low. Increased availability of long-acting methods in Nepal and similar settings may help to prevent unwanted pregnancy and attendant maternal mortality and morbidities. Initiation of modern contraception was high postabortion; however, 1-year discontinuation was high for the condom, pill and injectable, the methods most

A Floating Node Method for the Modelling of Discontinuities Within a Finite Element

NASA Technical Reports Server (NTRS)

Pinho, Silvestre T.; Chen, B. Y.; DeCarvalho, Nelson V.; Baiz, P. M.; Tay, T. E.

2013-01-01

This paper focuses on the accurate numerical representation of complex networks of evolving discontinuities in solids, with particular emphasis on cracks. The limitation of the standard finite element method (FEM) in approximating discontinuous solutions has motivated the development of re-meshing, smeared crack models, the eXtended Finite Element Method (XFEM) and the Phantom Node Method (PNM). We propose a new method which has some similarities to the PNM, but crucially: (i) does not introduce an error on the crack geometry when mapping to natural coordinates; (ii) does not require numerical integration over only part of a domain; (iii) can incorporate weak discontinuities and cohesive cracks more readily; (iv) is ideally suited for the representation of multiple and complex networks of (weak, strong and cohesive) discontinuities; (v) leads to the same solution as a finite element mesh where the discontinuity is represented explicitly; and (vi) is conceptually simpler than the PNM.

The Effects of Early Grade Retention on Student Outcomes over Time: Regression Discontinuity Evidence from Florida. Program on Education Policy and Governance Working Papers Series. PEPG 12-09

ERIC Educational Resources Information Center

Schwerdt, Guido; West, Martin R.

2012-01-01

A growing number of American states and school districts require students to meet basic performance standards in core academic subjects at key transition points in order to be promoted to the next grade. We exploit a discontinuity in the probability of third grade retention under a Florida test-based promotion policy to study the causal effect of…

The Cultural Discontinuity Hypothesis: An Appalachian American Perspective in Eastern Kentucky

ERIC Educational Resources Information Center

Conner, Timothy W., II

2017-01-01

K.M. Tyler et al. (2008) propose a quantitative method to measure differences between school and home experiences had by students of ethnic minority status and how such differences (cultural discontinuity) may affect psychological factors related to student achievement. Although study of cultural discontinuity has been applied to understanding…

An optimization-based approach for high-order accurate discretization of conservation laws with discontinuous solutions

NASA Astrophysics Data System (ADS)

Zahr, M. J.; Persson, P.-O.

2018-07-01

This work introduces a novel discontinuity-tracking framework for resolving discontinuous solutions of conservation laws with high-order numerical discretizations that support inter-element solution discontinuities, such as discontinuous Galerkin or finite volume methods. The proposed method aims to align inter-element boundaries with discontinuities in the solution by deforming the computational mesh. A discontinuity-aligned mesh ensures the discontinuity is represented through inter-element jumps while smooth basis functions interior to elements are only used to approximate smooth regions of the solution, thereby avoiding Gibbs' phenomena that create well-known stability issues. Therefore, very coarse high-order discretizations accurately resolve the piecewise smooth solution throughout the domain, provided the discontinuity is tracked. Central to the proposed discontinuity-tracking framework is a discrete PDE-constrained optimization formulation that simultaneously aligns the computational mesh with discontinuities in the solution and solves the discretized conservation law on this mesh. The optimization objective is taken as a combination of the deviation of the finite-dimensional solution from its element-wise average and a mesh distortion metric to simultaneously penalize Gibbs' phenomena and distorted meshes. It will be shown that our objective function satisfies two critical properties that are required for this discontinuity-tracking framework to be practical: (1) possesses a local minima at a discontinuity-aligned mesh and (2) decreases monotonically to this minimum in a neighborhood of radius approximately h / 2, whereas other popular discontinuity indicators fail to satisfy the latter. Another important contribution of this work is the observation that traditional reduced space PDE-constrained optimization solvers that repeatedly solve the conservation law at various mesh configurations are not viable in this context since severe overshoot and

Applied Multiple Linear Regression: A General Research Strategy

ERIC Educational Resources Information Center

Smith, Brandon B.

1969-01-01

Illustrates some of the basic concepts and procedures for using regression analysis in experimental design, analysis of variance, analysis of covariance, and curvilinear regression. Applications to evaluation of instruction and vocational education programs are illustrated. (GR)

78 FR 60375 - Norfolk Southern Railway Company-Discontinuance of Service Exemption-in Claiborne County, TN, and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

...); Docket No. AB 55 (Sub-No. 732X)] Norfolk Southern Railway Company--Discontinuance of Service Exemption... exemption under 49 CFR part 1152 Subpart F--Exempt Abandonments and Discontinuances of Service and Trackage Rights for NSR to discontinue service over, and for CSXT to discontinue trackage rights operations over...

Multiple Correlation versus Multiple Regression.

ERIC Educational Resources Information Center

Huberty, Carl J.

2003-01-01

Describes differences between multiple correlation analysis (MCA) and multiple regression analysis (MRA), showing how these approaches involve different research questions and study designs, different inferential approaches, different analysis strategies, and different reported information. (SLD)

Fertility and contraceptive adoption and discontinuation in rural Kenya.

PubMed

Ferguson, A G

1992-01-01

After a long period of slow progress, the recent uptake of contraceptive use in Kenya has been dramatic. This report describes adoption of a method and method switching and discontinuation among a cohort of married women aged 25-34 in two contrasting rural areas. A retrospective "fertility diary" completed by each woman provided information on spousal separation, reproductive status, and contraceptive use over a period of 46-48 months. Contraceptive prevalence rose rapidly over the period in both areas, with significant net adoption of injectables in both areas and of IUDs in one only. Method discontinuation was concentrated among users of pills, barrier methods, and "natural" methods, and only one-third of all discontinuations were voluntary. The wide differences between the two rural areas in contraceptive prevalence were not totally reflected in recent fertility levels, and the contribution of other proximate determinants of fertility, particularly postpartum amenorrhea and spousal separation, are discussed.

Time-dependent behavior of rough discontinuities under shearing conditions

NASA Astrophysics Data System (ADS)

Wang, Zhen; Shen, Mingrong; Ding, Wenqi; Jang, Boan; Zhang, Qingzhao

2018-02-01

The mechanical properties of rocks are generally controlled by their discontinuities. In this study, the time-dependent behavior of rough artificial joints under shearing conditions was investigated. Based on Barton’s standard profile lines, samples with artificial joint surfaces were prepared and used to conduct the shear and creep tests. The test results showed that the shear strength of discontinuity was linearly related to roughness, and subsequently an empirical equation was established. The long-term strength of discontinuity can be identified using the inflection point of the isocreep-rate curve, and it was linearly related to roughness. Furthermore, the ratio of long-term and instantaneous strength decreased with the increase of roughness. The shear-stiffness coefficient increased with the increase of shear rate, and the influence of shear rate on the shear stiffness coefficient decreased with the decrease of roughness. Further study of the mechanism revealed that these results could be attributed to the different time-dependent behavior of intact and joint rocks.

27 CFR 18.38 - Permanent discontinuance.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Permanent discontinuance. 18.38 Section 18.38 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS PRODUCTION OF VOLATILE FRUIT-FLAVOR CONCENTRATE Qualification Changes...

27 CFR 18.38 - Permanent discontinuance.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Permanent discontinuance. 18.38 Section 18.38 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL PRODUCTION OF VOLATILE FRUIT-FLAVOR CONCENTRATE Qualification Changes...

27 CFR 18.38 - Permanent discontinuance.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Permanent discontinuance. 18.38 Section 18.38 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL PRODUCTION OF VOLATILE FRUIT-FLAVOR CONCENTRATE Qualification Changes...

27 CFR 18.38 - Permanent discontinuance.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Permanent discontinuance. 18.38 Section 18.38 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS PRODUCTION OF VOLATILE FRUIT-FLAVOR CONCENTRATE Qualification Changes...

Schrödinger propagation of initial discontinuities leads to divergence of moments

NASA Astrophysics Data System (ADS)

Marchewka, A.; Schuss, Z.

2009-09-01

We show that the large phase expansion of the Schrödinger propagation of an initially discontinuous wave function leads to the divergence of average energy, momentum, and displacement, rendering them unphysical states. If initially discontinuous wave functions are considered to be approximations to continuous ones, the determinant of the spreading rate of these averages is the maximal gradient of the initial wave function. Therefore a dilemma arises between the inclusion of discontinuous wave functions in quantum mechanics and the requirement of finite moments.

Substructures of the mantle transition-zone discontinuities and compositional heterogeneities in the mid-mantle

NASA Astrophysics Data System (ADS)

Wei, S. S.; Shearer, P. M.

2017-12-01

The mantle transition-zone discontinuities are usually attributed to isochemical phase transformations of olivine and its high-pressure polymorphs. However, recent seismic observations have shown complexities in these discontinuities that cannot be explained by conventional models of thermal variations. Here we analyse SS precursor stacking results to investigate global mantle transition-zone properties. The precursor waveforms provide information on the seismic velocity and density profiles across and near the major mantle discontinuities. A sporadic low-velocity layer immediately above the 410-km discontinuity is observed worldwide, including East Asia, western North America, eastern South America, and 33-50% of the resolved Pacific Ocean. The 520-km discontinuity exhibits significant variations in its sharpness and depth, and occasionally appears to be split. Structures underlying the 660-km discontinuity show even larger complexities: a sub-discontinuity at 700-800 km depth is detected in some regions, of which some require a positive velocity gradient whereas others have a negative gradient. All of these lateral variations show no geographical correlation with discontinuity topography or tomographic models of seismic velocity, suggesting that they are not caused by regional thermal anomalies. Alternatively, our observations can be explained by compositional heterogeneities in the mid-mantle, including major minerals and volatile content, which may result in additional phase transformations and partial melting. These compositional heterogeneities should be taken into account in future geodynamic models of mantle convection and the deep water cycle.

Discontinued Information and Communication Technology Usage among Older Adults in Continuing Care Retirement Communities in the United States.

PubMed

Rikard, R V; Berkowsky, Ronald W; Cotten, Shelia R

2018-01-01

usage may be more pronounced among independent living residents. Limitations in the number of IADL impairments is a key factor leading to discontinued use of ICTs among CCRC residents, suggesting that designers of ICTs should be cognizant of the cognitive and physical limitations among this group. © 2017 S. Karger AG, Basel.

An Analysis of Contraceptive Discontinuation among Female, Reversible Method Users in Urban Honduras

PubMed Central

Barden-O’Fallon, Janine; Speizer, Ilene S.; Cálix, Javier; Rodriguez, Francisco

2013-01-01

A panel study examining the effects of individual characteristics, side effects experienced, and service quality on contraceptive discontinuation was undertaken in four urban areas of Honduras. Data were collected from October 2006 to December 2007. The baseline population included 800 women aged 15–44 who were new or continuing users of the injectable, IUD, or oral contraceptive pill. A total of 671 women (84%) were re-interviewed after one year. Life tables and Cox proportional hazards models are used to present discontinuation rates and factors associated with contraceptive discontinuation. Among new users, discontinuation of the baseline method at 12 months was high (45%); especially for users of the injectable (50%). In the hazards model, service quality had little effect on discontinuation, while individual characteristics and the experience of specific side effects showed significant effects. The results suggest that programs should emphasize continuous contraceptive coverage rather than continuous use of a particular method. PMID:21500697

Numerical Modeling of Earthquake-Induced Landslide Using an Improved Discontinuous Deformation Analysis Considering Dynamic Friction Degradation of Joints

NASA Astrophysics Data System (ADS)

Huang, Da; Song, Yixiang; Cen, Duofeng; Fu, Guoyang

2016-12-01

Discontinuous deformation analysis (DDA) as an efficient technique has been extensively applied in the dynamic simulation of discontinuous rock mass. In the original DDA (ODDA), the Mohr-Coulomb failure criterion is employed as the judgment principle of failure between contact blocks, and the friction coefficient is assumed to be constant in the whole calculation process. However, it has been confirmed by a host of shear tests that the dynamic friction of rock joints degrades. Therefore, the friction coefficient should be gradually reduced during the numerical simulation of an earthquake-induced rockslide. In this paper, based on the experimental results of cyclic shear tests on limestone joints, exponential regression formulas are fitted for dynamic friction degradation, which is a function of the relative velocity, the amplitude of cyclic shear displacement and the number of its cycles between blocks with an edge-to-edge contact. Then, an improved DDA (IDDA) is developed by implementing the fitting regression formulas and a modified removing technique of joint cohesion, in which the cohesion is removed once the `sliding' or `open' state between blocks appears for the first time, into the ODDA. The IDDA is first validated by comparing with the theoretical solutions of the kinematic behaviors of a sliding block on an inclined plane under dynamic loading. Then, the program is applied to model the Donghekou landslide triggered by the 2008 Wenchuan earthquake in China. The simulation results demonstrate that the dynamic friction degradation of joints has great influences on the runout and velocity of sliding mass. Moreover, the friction coefficient possesses higher impact than the cohesion of joints on the kinematic behaviors of the sliding mass.

Second tyrosine kinase inhibitor discontinuation attempt in patients with chronic myeloid leukemia.

PubMed

Legros, Laurence; Nicolini, Franck E; Etienne, Gabriel; Rousselot, Philippe; Rea, Delphine; Giraudier, Stéphane; Guerci-Bresler, Agnès; Huguet, Françoise; Gardembas, Martine; Escoffre, Martine; Ianotto, Jean-Christophe; Noël, Marie-Pierre; Varet, Bruno R; Pagliardini, Thomas; Touitou, Irit; Morisset, Stéphane; Mahon, Francois-Xavier

2017-11-15

Several studies have demonstrated that approximately one-half of patients with chronic myeloid leukemia (CML) who receive treatment with tyrosine kinase inhibitors (TKIs) and achieve and maintain a deep molecular response (DMR) are able to successfully discontinue therapy. In patients who have a molecular relapse, a DMR is rapidly regained upon treatment re-initiation. The authors report the results from RE-STIM, a French observational, multicenter study that evaluated treatment-free remission (TFR) in 70 patients who re-attempted TKI discontinuation after a first unsuccessful attempt. After the second TKI discontinuation attempt, the trigger for treatment re-introduction was the loss of a major molecular response in all patients. The median follow-up was 38.3 months (range, 4.7-117 months), and 45 patients (64.3%) lost a major molecular response after a median time off therapy of 5.3 months (range, 2-42 months). TFR rates at 12, 24, and 36 months were 48% (95% confidence interval [CI], 37.6%-61.5%), 42% (95% CI, 31.5%-55.4%), and 35% (95% CI, 24.4%-49.4%), respectively. No progression toward advanced-phase CML occurred, and no efficacy issue was observed upon TKI re-introduction. In univariate analysis, the speed of molecular relapse after the first TKI discontinuation attempt was the only factor significantly associated with outcome. The TFR rate at 24 months was 72% (95% CI, 48.8%-100%) in patients who remained in DMR within the first 3 months after the first TKI discontinuation and 36% (95% CI, 25.8%-51.3%) for others. This study is the first to demonstrate that a second TKI discontinuation attempt is safe and that a first failed attempt at discontinuing TKI does not preclude a second successful attempt. Cancer 2017;123:4403-10. © 2017 American Cancer Society. © 2017 American Cancer Society.

Extreme interplanetary rotational discontinuities at 1 AU

NASA Astrophysics Data System (ADS)

Lepping, R. P.; Wu, C.-C.

2005-11-01

This study is concerned with the identification and description of a special subset of four Wind interplanetary rotational discontinuities (from an earlier study of 134 directional discontinuities by Lepping et al. (2003)) with some "extreme" characteristics, in the sense that every case has (1) an almost planar current sheet surface, (2) a very large discontinuity angle (ω), (3) at least moderately strong normal field components (>0.8 nT), and (4) the overall set has a very broad range of transition layer thicknesses, with one being as thick as 50 RE and another at the other extreme being 1.6 RE, most being much thicker than are usually studied. Each example has a well-determined surface normal (n) according to minimum variance analysis and corroborated via time delay checking of the discontinuity with observations at IMP 8 by employing the local surface planarity. From the variance analyses, most of these cases had unusually large ratios of intermediate-to-minimum eigenvalues (λI/λmin), being on average 32 for three cases (with a fourth being much larger), indicating compact current sheet transition zones, another (the fifth) extreme property. For many years there has been a controversy as to the relative distribution of rotational (RDs) to tangential discontinuities (TDs) in the solar wind at 1 AU (and elsewhere, such as between the Sun and Earth), even to the point where some authors have suggested that RDs with large ∣Bn∣s are probably not generated or, if generated, are unstable and therefore very rare. Some of this disagreement apparently has been due to the different selection criteria used, e.g., some allowed eigenvalue ratios (λI/λmin) to be almost an order of magnitude lower than 32 in estimating n, usually introducing unacceptable error in n and therefore also in ∣Bn∣. However, we suggest that RDs may not be so rare at 1 AU, but good quality cases (where ∣Bn∣ confidently exceeds the error in ∣Bn∣) appear to be uncommon, and further

38 CFR 21.4135 - Discontinuance dates.

Code of Federal Regulations, 2013 CFR

2013-07-01

... receive educational assistance under the Montgomery GI Bill—Active Duty. If a veteran makes a valid election, as provided in § 21.7045(d), to receive educational assistance under the Montgomery GI Bill... assistance must be discontinued or who becomes restricted to payment of educational assistance allowance at a...

Local Discontinuous Galerkin Methods for the Cahn-Hilliard Type Equations

DTIC Science & Technology

2007-01-01

Kuramoto-Sivashinsky equations , the Ito-type coupled KdV equa- tions, the Kadomtsev - Petviashvili equation , and the Zakharov-Kuznetsov equation . A common...Local discontinuous Galerkin methods for the Cahn-Hilliard type equations Yinhua Xia∗, Yan Xu† and Chi-Wang Shu ‡ Abstract In this paper we develop...local discontinuous Galerkin (LDG) methods for the fourth-order nonlinear Cahn-Hilliard equation and system. The energy stability of the LDG methods is

Quasi-experimental study designs series-paper 6: risk of bias assessment.

PubMed

Waddington, Hugh; Aloe, Ariel M; Becker, Betsy Jane; Djimeu, Eric W; Hombrados, Jorge Garcia; Tugwell, Peter; Wells, George; Reeves, Barney

2017-09-01

Rigorous and transparent bias assessment is a core component of high-quality systematic reviews. We assess modifications to existing risk of bias approaches to incorporate rigorous quasi-experimental approaches with selection on unobservables. These are nonrandomized studies using design-based approaches to control for unobservable sources of confounding such as difference studies, instrumental variables, interrupted time series, natural experiments, and regression-discontinuity designs. We review existing risk of bias tools. Drawing on these tools, we present domains of bias and suggest directions for evaluation questions. The review suggests that existing risk of bias tools provide, to different degrees, incomplete transparent criteria to assess the validity of these designs. The paper then presents an approach to evaluating the internal validity of quasi-experiments with selection on unobservables. We conclude that tools for nonrandomized studies of interventions need to be further developed to incorporate evaluation questions for quasi-experiments with selection on unobservables. Copyright © 2017 Elsevier Inc. All rights reserved.

Introduction to the special issue on discontinuity of fluvial systems

NASA Astrophysics Data System (ADS)

Burchsted, Denise; Daniels, Melinda; Wohl, Ellen E.

2014-01-01

Fluvial systems include natural and human-created barriers that modify local base level; as such, these discontinuities alter the longitudinal flux of water and sediment by storing, releasing, or changing the flow path of those materials. Even in the absence of distinct barriers, fluvial systems are typically discontinuous and patchy. The size of fluvial discontinuities ranges across scales from 100 m, such as riffles, to 104 m, such as lava dams or major landslides. The frequency of occurrence appears to be inversely related to size, with creation and failure of the small features, such as beaver dams, occurring on a time scale of 100 to 101 years and a frequency of occurrence at scales as low as 101 m. In contrast, larger scale discontinuities, such as lava dams, can last for time scales up to 105 years and have a frequency of occurrence of approximately 104 m. The heterogeneity generated by features is an essential part of river networks and should be considered as part of river management. Therefore, we suggest that "natural" dams are a useful analog for human dams when evaluating options for river restoration. This collection of papers on the studies of natural dams includes bedrock barriers, log jams and beaver dams. The collection also addresses the discontinuity generated by a floodplain — in the absence of an obvious barrier in the channel — and tools for evaluation of riverbed heterogeneity. It is completed with a study of impact of human dams on floodplain sedimentation. These papers will help geomorphologists and river managers understand the factors that control river heterogeneity across scales and around the world.

A High Order Discontinuous Galerkin Method for 2D Incompressible Flows

NASA Technical Reports Server (NTRS)

Liu, Jia-Guo; Shu, Chi-Wang

1999-01-01

In this paper we introduce a high order discontinuous Galerkin method for two dimensional incompressible flow in vorticity streamfunction formulation. The momentum equation is treated explicitly, utilizing the efficiency of the discontinuous Galerkin method The streamfunction is obtained by a standard Poisson solver using continuous finite elements. There is a natural matching between these two finite element spaces, since the normal component of the velocity field is continuous across element boundaries. This allows for a correct upwinding gluing in the discontinuous Galerkin framework, while still maintaining total energy conservation with no numerical dissipation and total enstrophy stability The method is suitable for inviscid or high Reynolds number flows. Optimal error estimates are proven and verified by numerical experiments.

Bilateral filter regularized accelerated Demons for improved discontinuity preserving registration.

PubMed

Demirović, D; Šerifović-Trbalić, A; Prljača, N; Cattin, Ph C

2015-03-01

The classical accelerated Demons algorithm uses Gaussian smoothing to penalize oscillatory motion in the displacement fields during registration. This well known method uses the L2 norm for regularization. Whereas the L2 norm is known for producing well behaving smooth deformation fields it cannot properly deal with discontinuities often seen in the deformation field as the regularizer cannot differentiate between discontinuities and smooth part of motion field. In this paper we propose replacement the Gaussian filter of the accelerated Demons with a bilateral filter. In contrast the bilateral filter not only uses information from displacement field but also from the image intensities. In this way we can smooth the motion field depending on image content as opposed to the classical Gaussian filtering. By proper adjustment of two tunable parameters one can obtain more realistic deformations in a case of discontinuity. The proposed approach was tested on 2D and 3D datasets and showed significant improvements in the Target Registration Error (TRE) for the well known POPI dataset. Despite the increased computational complexity, the improved registration result is justified in particular abdominal data sets where discontinuities often appear due to sliding organ motion. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficient design of gain-flattened multi-pump Raman fiber amplifiers using least squares support vector regression

NASA Astrophysics Data System (ADS)

Chen, Jing; Qiu, Xiaojie; Yin, Cunyi; Jiang, Hao

2018-02-01

An efficient method to design the broadband gain-flattened Raman fiber amplifier with multiple pumps is proposed based on least squares support vector regression (LS-SVR). A multi-input multi-output LS-SVR model is introduced to replace the complicated solving process of the nonlinear coupled Raman amplification equation. The proposed approach contains two stages: offline training stage and online optimization stage. During the offline stage, the LS-SVR model is trained. Owing to the good generalization capability of LS-SVR, the net gain spectrum can be directly and accurately obtained when inputting any combination of the pump wavelength and power to the well-trained model. During the online stage, we incorporate the LS-SVR model into the particle swarm optimization algorithm to find the optimal pump configuration. The design results demonstrate that the proposed method greatly shortens the computation time and enhances the efficiency of the pump parameter optimization for Raman fiber amplifier design.

Phototoxicity of B-RAF inhibitors: Exclusively due to UVA radiation and rapidly regressive.

PubMed

Gabeff, Romain; Dutartre, Hervé; Khammari, Amir; Boisrobert, Aurélie; Nguyen, Jean-Michel; Quereux, Gaëlle; Brocard, Anabelle; Saint-Jean, Mélanie; Peuvrel, Lucie; Dreno, Brigitte

2015-01-01

New targeted melanoma therapies such as B-RAF inhibitors have shown high and promising clinical benefit but have cutaneous side-effects, including photosensitivity, which is triggered in the UVA radiation spectrum. However, visible spectrum implication has not yet been investigated. We conducted a study to determine whether visible light also contributes to the phototoxicity action spectrum of vemurafenib. The secondary end points were to determine the time to complete regression of the phototoxicity post-vemurafenib discontinuation and whether there was a significant difference between the UVA radiation immediate reactivity cut-offs, in patients treated with vemurafenib vs. those treated with dabrafenib. This prospective, observational study included patients with B-RAF mutant metastatic melanoma: 34 patients treated with vemurafenib and 9 with dabrafenib. The visible-light phototest results in patients treated with vemurafenib were all negative before and after 2 months of treatment. The UVA radiation phototests conducted 1 or 2 weeks post-vemurafenib discontinuation in 4 patients showed a normalised UVA-radiation reactivity cut-off. UVA radiation phototests after 2 months of treatment were conducted for all patients. The UVA radiation reactivity cut-off had been lowered for 30 patients (88%) on vemurafenib and 3 patients (33%) on dabrafenib. The median UVA radiation reactivity cut-off was 12 J/cm(2) for the patients on vemurafenib and 20 J/cm(2) for the patients on dabrafenib. B-RAF inhibitor phototoxicity is exclusively triggered by UVA radiation and resolves rapidly post-treatment discontinuation. A significant difference between the UVA immediate reactivity cut-offs, vemurafenib vs. dabrafenib, explains the difference in the clinical photosensitivity rates reported in the clinical trials.

On the structure of contact binaries. I - The contact discontinuity

NASA Technical Reports Server (NTRS)

Shu, F. H.; Lubow, S. H.; Anderson, L.

1976-01-01

The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

Continuity and Discontinuity in Education: Example of Transition from Preschool to School

ERIC Educational Resources Information Center

Babic, Nada

2017-01-01

This article reconsiders multiple perspectives about continuity and discontinuity of early childhood education. Theoretical starting points, childhood policies and research of continuity and discontinuity exemplified through transition to school, are promising in rethinking and creating productive practices of childhood in different sociocultural…

Reasons for Discontinuing Hashish Use in a Group of Central European Athletes.

ERIC Educational Resources Information Center

Duncan, David F.

1988-01-01

Examined self-reported reasons for discontinuing marijuana use among 61 former marijuana using students at central European sports training facility. Most common reasons given for discontinuing marijuana use were dislike of effects, athletic training regimen, health reasons, and mental/emotional problems. (Author/NB)

Healthcare Resource Waste Associated with Patient Nonadherence and Early Discontinuation of Traditional Continuous Glucose Monitoring in Real-World Settings: A Multicountry Analysis.

PubMed

Yu, Shengsheng; Varughese, Biju; Li, Zhiyi; Kushner, Pam R

2018-06-01

Traditional continuous glucose monitoring (CGM) provides detailed information on glucose patterns and trends to inform daily diabetes management decisions, which is particularly beneficial for patients with a history of hypoglycemia unawareness. However, a high level of patient adherence (≥70%) is required to achieve clinical benefits. The aim of this study was to assess the impact of real-world patient nonadherence and early discontinuation on healthcare resource use. A cost calculator was designed to evaluate monthly healthcare resource waste within the first year of traditional CGM initiation by combining estimates of real-world nonadherence and early discontinuation from the literature with the wholesale acquisition costs of the current technology in the United States (for a commercial payer and for Medicare), or its equivalent in Sweden, Germany, or the Netherlands. Based on an early discontinuation rate of 27% and nonadherence rates of 13.9%-31.1% over the 12 months following initiation, the healthcare resource waste associated with nonadherence and early discontinuation was $220,289 and $21,775, respectively, for every 100 patients initiating CGM in the U.S. commercial payer scenario. In the Medicare scenario, the corresponding figures were $72,648 and $5,675, respectively. In both scenarios, nonadherence and early discontinuation accounted for ∼24% of resources being wasted within the first year of CGM initiation. Similar results were observed using the local costs in the other countries analyzed. The healthcare resource waste associated with traditional CGM nonadherence and early discontinuation warrants deliberate consideration when selecting suitable patients for this technology.

Estimation of discontinuous coefficients in parabolic systems: Applications to reservoir simulation

NASA Technical Reports Server (NTRS)

Lamm, P. D.

1984-01-01

Spline based techniques for estimating spatially varying parameters that appear in parabolic distributed systems (typical of those found in reservoir simulation problems) are presented. The problem of determining discontinuous coefficients, estimating both the functional shape and points of discontinuity for such parameters is discussed. Convergence results and a summary of numerical performance of the resulting algorithms are given.

Fatigue behavior of 5Ni-Cr-Mo-V steel weldments containing fabrication discontinuities

NASA Technical Reports Server (NTRS)

Gill, Steven J.; Hauser, Joseph A., II; Crooker, Thomas W.; Kruse, Brian J.; Menon, Ravi

1988-01-01

The applicability of linear elastic fracture mechanics to characterize the fatigue behavior of high-strength steel weldments containing lack-of-penetration (LOP) and slag/lack-of-fusion (S/LOF) discontinuities is explored. Full penetration, double-V butt welds with reinforcements removed were tested under zero-to-tension axial loading. Various filler metals and welding techniques were used. Both sound welds and welds containing discontinuities were cycled to failure. Where possible, cycles to crack initiation were estimated by strain gage measurements. The fracture mechanics approach was successful in correlating the fatigue lifetimes of specimens containing single LOP discontinuities of varying size. However, the fatigue behavior of specimens containing multiple S/LOF discontinuities proved to be much more complex and difficult to analyze.

Global Discontinuity Structure of the Mantle Transition Zone from Finite-Frequency Tomography of SS Precursors

NASA Astrophysics Data System (ADS)

Guo, Z.; Zhou, Y.

2017-12-01

We report global structure of the 410-km and 660-km discontinuities from finite-frequency tomography using frequency-dependent traveltime measurements of SS precursors recorded at the Global Seismological Network (GSN). Finite-frequency sensitivity kernels for discontinuity depth perturbations are calculated in the framework of traveling-wave mode coupling. We parametrize the global discontinuities using a set of spherical triangular grid points and solve the tomographic inverse problem based on singular value decomposition. Our global 410-km and 660-km discontinuity models reveal distinctly different characteristics beneath the oceans and subduction zones. In general, oceanic regions are associated with a thinner mantle transition zone and depth perturbations of the 410-km and 660-km discontinuities are anti-correlated, in agreement with a thermal origin and an overall warm and dry mantle beneath the oceans. The perturbations are not uniform throughout the oceans but show strong small-scale variations, indicating complex processes in the mantle transition zone. In major subduction zones (except for South America where data coverage is sparse), depth perturbations of the 410-km and 660-km discontinuities are correlated, with both the 410-km and the 660-km discontinuities occurring at greater depths. The distributions of the anomalies are consistent with cold stagnant slabs just above the 660-km discontinuity and ascending return flows in a superadiabatic upper mantle.

Seismic imaging of lithospheric discontinuities and continental evolution

NASA Astrophysics Data System (ADS)

Bostock, M. G.

1999-09-01

Discontinuities in physical properties within the continental lithosphere reflect a range of processes that have contributed to craton stabilization and evolution. A survey of recent seismological studies concerning lithospheric discontinuities is made in an attempt to document their essential characteristics. Results from long-period seismology are inconsistent with the presence of continuous, laterally invariant, isotropic boundaries within the upper mantle at the global scale. At regional scales, two well-defined interfaces termed H (˜60 km depth) and L (˜200 km depth) of continental affinity are identified, with the latter boundary generally exhibiting an anisotropic character. Long-range refraction profiles are frequently characterized by subcontinental mantle that exhibits a complex stratification within the top 200 km. The shallow layering of this package can behave as an imperfect waveguide giving rise to the so-called teleseismic Pn phase, while the L-discontinuity may define its lower base as the culmination of a low velocity zone. High-resolution, seismic reflection profiling provides sufficient detail in a number of cases to document the merging of mantle interfaces into lower continental crust below former collisional sutures and magmatic arcs, thus unambiguously identifying some lithospheric discontinuities with thrust faults and subducted oceanic lithosphere. Collectively, these and other seismic observations point to a continental lithosphere whose internal structure is dominated by a laterally variable, subhorizontal layering. This stratigraphy appears to be more pronounced at shallower lithospheric levels, includes dense, anisotropic layers of order 10 km in thickness, and exhibits horizontal correlation lengths comparable to the lateral dimensions of overlying crustal blocks. A model of craton evolution which relies on shallow subduction as a principal agent of craton stabilization is shown to be broadly compatible with these characteristics.

High-order dynamic modeling and parameter identification of structural discontinuities in Timoshenko beams by using reflection coefficients

NASA Astrophysics Data System (ADS)

Fan, Qiang; Huang, Zhenyu; Zhang, Bing; Chen, Dayue

2013-02-01

Properties of discontinuities, such as bolt joints and cracks in the waveguide structures, are difficult to evaluate by either analytical or numerical methods due to the complexity and uncertainty of the discontinuities. In this paper, the discontinuity in a Timoshenko beam is modeled with high-order parameters and then these parameters are identified by using reflection coefficients at the discontinuity. The high-order model is composed of several one-order sub-models in series and each sub-model consists of inertia, stiffness and damping components in parallel. The order of the discontinuity model is determined based on the characteristics of the reflection coefficient curve and the accuracy requirement of the dynamic modeling. The model parameters are identified through the least-square fitting iteration method, of which the undetermined model parameters are updated in iteration to fit the dynamic reflection coefficient curve with the wave-based one. By using the spectral super-element method (SSEM), simulation cases, including one-order discontinuities on infinite- and finite-beams and a two-order discontinuity on an infinite beam, were employed to evaluate both the accuracy of the discontinuity model and the effectiveness of the identification method. For practical considerations, effects of measurement noise on the discontinuity parameter identification are investigated by adding different levels of noise to the simulated data. The simulation results were then validated by the corresponding experiments. Both the simulation and experimental results show that (1) the one-order discontinuities can be identified accurately with the maximum errors of 6.8% and 8.7%, respectively; (2) and the high-order discontinuities can be identified with the maximum errors of 15.8% and 16.2%, respectively; and (3) the high-order model can predict the complex discontinuity much more accurately than the one-order discontinuity model.

Simplified Discontinuous Galerkin Methods for Systems of Conservation Laws with Convex Extension

NASA Technical Reports Server (NTRS)

Barth, Timothy J.

1999-01-01

Simplified forms of the space-time discontinuous Galerkin (DG) and discontinuous Galerkin least-squares (DGLS) finite element method are developed and analyzed. The new formulations exploit simplifying properties of entropy endowed conservation law systems while retaining the favorable energy properties associated with symmetric variable formulations.

27 CFR 18.38 - Permanent discontinuance.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Permanent discontinuance. 18.38 Section 18.38 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... by the Office of Management and Budget under control number 1512-0046) [T.D. ATF-104, 47 FR 23921...

A Discontinuous Potential Model for Protein-Protein Interactions.

PubMed

Shao, Qing; Hall, Carol K

2016-01-01

Protein-protein interactions play an important role in many biologic and industrial processes. In this work, we develop a two-bead-per-residue model that enables us to account for protein-protein interactions in a multi-protein system using discontinuous molecular dynamics simulations. This model deploys discontinuous potentials to describe the non-bonded interactions and virtual bonds to keep proteins in their native state. The geometric and energetic parameters are derived from the potentials of mean force between sidechain-sidechain, sidechain-backbone, and backbone-backbone pairs. The energetic parameters are scaled with the aim of matching the second virial coefficient of lysozyme reported in experiment. We also investigate the performance of several bond-building strategies.

Fundamental gaps with approximate density functionals: The derivative discontinuity revealed from ensemble considerations

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

Kraisler, Eli; Kronik, Leeor

2014-05-14

The fundamental gap is a central quantity in the electronic structure of matter. Unfortunately, the fundamental gap is not generally equal to the Kohn-Sham gap of density functional theory (DFT), even in principle. The two gaps differ precisely by the derivative discontinuity, namely, an abrupt change in slope of the exchange-correlation energy as a function of electron number, expected across an integer-electron point. Popular approximate functionals are thought to be devoid of a derivative discontinuity, strongly compromising their performance for prediction of spectroscopic properties. Here we show that, in fact, all exchange-correlation functionals possess a derivative discontinuity, which arises naturallymore » from the application of ensemble considerations within DFT, without any empiricism. This derivative discontinuity can be expressed in closed form using only quantities obtained in the course of a standard DFT calculation of the neutral system. For small, finite systems, addition of this derivative discontinuity indeed results in a greatly improved prediction for the fundamental gap, even when based on the most simple approximate exchange-correlation density functional – the local density approximation (LDA). For solids, the same scheme is exact in principle, but when applied to LDA it results in a vanishing derivative discontinuity correction. This failure is shown to be directly related to the failure of LDA in predicting fundamental gaps from total energy differences in extended systems.« less

Effective Teacher Retention Bonuses: Evidence From Tennessee

ERIC Educational Resources Information Center

Springer, Matthew G.; Swain, Walker A.; Rodriguez, Luis A.

2016-01-01

We report findings from a quasi-experimental evaluation of the recently implemented US$5,000 retention bonus program for effective teachers in Tennessee's Priority Schools. We estimate the impact of the program on teacher retention using a fuzzy regression discontinuity design by exploiting a discontinuity in the probability of treatment…

A PDE approach for quantifying and visualizing tumor progression and regression

NASA Astrophysics Data System (ADS)

Sintay, Benjamin J.; Bourland, J. Daniel

2009-02-01

Quantification of changes in tumor shape and size allows physicians the ability to determine the effectiveness of various treatment options, adapt treatment, predict outcome, and map potential problem sites. Conventional methods are often based on metrics such as volume, diameter, or maximum cross sectional area. This work seeks to improve the visualization and analysis of tumor changes by simultaneously analyzing changes in the entire tumor volume. This method utilizes an elliptic partial differential equation (PDE) to provide a roadmap of boundary displacement that does not suffer from the discontinuities associated with other measures such as Euclidean distance. Streamline pathways defined by Laplace's equation (a commonly used PDE) are used to track tumor progression and regression at the tumor boundary. Laplace's equation is particularly useful because it provides a smooth, continuous solution that can be evaluated with sub-pixel precision on variable grid sizes. Several metrics are demonstrated including maximum, average, and total regression and progression. This method provides many advantages over conventional means of quantifying change in tumor shape because it is observer independent, stable for highly unusual geometries, and provides an analysis of the entire three-dimensional tumor volume.

Accurate solution of the Poisson equation with discontinuities

NASA Astrophysics Data System (ADS)

Nave, Jean-Christophe; Marques, Alexandre; Rosales, Rodolfo

2017-11-01

Solving the Poisson equation in the presence of discontinuities is of great importance in many applications of science and engineering. In many cases, the discontinuities are caused by interfaces between different media, such as in multiphase flows. These interfaces are themselves solutions to differential equations, and can assume complex configurations. For this reason, it is convenient to embed the interface into a regular triangulation or Cartesian grid and solve the Poisson equation in this regular domain. We present an extension of the Correction Function Method (CFM), which was developed to solve the Poisson equation in the context of embedded interfaces. The distinctive feature of the CFM is that it uses partial differential equations to construct smooth extensions of the solution in the vicinity of interfaces. A consequence of this approach is that it can achieve high order of accuracy while maintaining compact discretizations. The extension we present removes the restrictions of the original CFM, and yields a method that can solve the Poisson equation when discontinuities are present in the solution, the coefficients of the equation (material properties), and the source term. We show results computed to fourth order of accuracy in two and three dimensions. This work was partially funded by DARPA, NSF, and NSERC.

Why do couples discontinue unlimited free IVF treatments?

PubMed

Lande, Yechezkel; Seidman, Daniel S; Maman, Ettie; Baum, Micha; Hourvitz, Ariel

2015-03-01

Worldwide, IVF is often discontinued before a live birth is achieved due to high costs. Even when partial financial coverage is provided, often medical providers advise treatment discontinuation. In Israel, unlimited IVF is offered free of charge for a couples' first two children. Our objective was to assess the reasons couples discontinue IVF treatments before achieving two children in a completely unlimited cost-free environment. This cohort study included all primary infertile women, <35 years, referred for their first IVF cycle to Sheba IVF unit between 2001 and 2002. Patients were followed until February 2012. Those who ceased treatments for 12 months were interviewed to assess the main reason they ceased treatments. Of the 134 couples included, only 46 ceased IVF treatments without achieving two children, after performing an average of 6.2 IVF cycles to achieve their first birth. The reasons given were: lost hope of success (13), psychological burden (18), divorce (6), medical staff recommendation (5), bureaucratic difficulties (3) and general medical condition (1). The main reasons for "drop out" in our cost-free environment were as follows: psychological burden and lost hope of success. Due to high availability of treatments, medical staff recommendation was a less significant factor in our study.

Does research into contraceptive method discontinuation address women's own reasons? A critical review.

PubMed

Inoue, Kumiyo; Barratt, Alexandra; Richters, Juliet

2015-10-01

To examine the clinical and epidemiological literature addressing contraceptive method change or discontinuation and to assess whether the documented reasons reflected women's experiences. Major databases including Medline and PsycINFO were searched using keywords related to contraception and discontinuation, adherence and satisfaction, for articles published between January 2003 and February 2013. Studies in developed countries that focused on women of reproductive age and reasons for method change or discontinuation were included. Reasons reported were categorised and examined. A total of 123 papers were reviewed in detail. Medical terminology was generally used to describe reasons for method discontinuation. The top two reported reasons were bleeding and pregnancy, but there was a lack of consensus about the categorisation of reasons. Broad categories that were not self-explanatory were included in more than half of the papers, often without further explanation. Only 12 studies expanded on categories containing 'other', 'non-medical' or 'personal' reasons. Eight papers included categories that attributed discontinuation to the participant, such as 'dissatisfied with method'. Studies of reasons for discontinuation of contraceptives do not well describe women's specific reasons. Studies rely heavily on medical terms and often fail to document women's subjective experiences. Future studies should create an opportunity for women to articulate their non-medical reasons in their own words, including those related to their sexual lives. Furthermore, researchers should distinguish, if possible, between reasons for discontinuation of a method and reasons for ceasing participation in a research study. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Magnetic field directional discontinuities - Characteristics between 0.46 and 1.0 AU

NASA Technical Reports Server (NTRS)

Lepping, R. P.; Behannon, K. W.

1986-01-01

Based on Mariner 10 data, a statistical survey and an application of the Sonnerup-Cahill variance procedure to a visual identification with 1.2-s averages for time intervals corresponding to the equally spaced heliocentric distances of 1.0, 0.72 and 0.46 AU, are employed to study the characteristics of directional discontinuities (DDs) in the interplanetary magnetic field. Analysis using two methods demonstrated that the ratio of tangential discontinuities (TDs) to rotational discontinuities (RDs) decreased with decreasing radial distance. Decreases in average discontinuity thickness of 41 percent between 1.0 and 0.72 AU, and 56 percent between 1.0 and 0.46 AU, were found for both TDs and RDs, in agreement with Pioneer 10 data between 1 and 5 AU. Normalization of the individual DD thicknesses with respect to the estimated local proton gyroradius (R sub L) gave a nearly constant average thickness at the three locations, 36 + or - 5 R sub L, for both RDs and TDs.

14 CFR 16 - Objective Classification-Discontinued Operations

Code of Federal Regulations, 2012 CFR

2012-01-01

... CERTIFICATED AIR CARRIERS Profit and Loss Classification Section 16 Objective Classification—Discontinued... the disposal of investor controlled companies and nontransport ventures whether sold, abandoned, spun... transport or transport-related operations. (b) This account shall be subdivided as follows by all air...

48 CFR 49.302 - Discontinuance of vouchers.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Discontinuance of vouchers. 49.302 Section 49.302 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT TERMINATION OF CONTRACTS Additional Principles for Cost-Reimbursement Contracts Terminated for...

Experimental and Numerical Analysis of Performance Discontinuity of a Pump-Turbine under Pumping Mode

NASA Astrophysics Data System (ADS)

Zhang, X.; Burgstaller, R.; Lai, X.; Gehrer, A.; Kefalas, A.; Pang, Y.

2016-11-01

The performance discontinuity of a pump-turbine under pumping mode is harmful to stable operation of units in hydropower station. In this paper, the performance discontinuity phenomenon of the pump-turbine was studied by means of experiment and numerical simulation. In the experiment, characteristics of the pump-turbine with different diffuser vane openings were tested in order to investigate the effect of pumping casing to the performance discontinuity. While other effects such as flow separation and rotating stall are known to have an effect on the discontinuity, the present studied test cases show that prerotation is the dominating effect for the instability, positions of the positive slope of characteristics are almost the same in different diffuser vane opening conditions. The impeller has principal effect to the performance discontinuity. In the numerical simulation, CFD analysis of tested pump-turbine has been done with k-ω and SST turbulence model. It is found that the position of performance curve discontinuity corresponds to flow recirculation at impeller inlet. Flow recirculation at impeller inlet is the cause of the discontinuity of characteristics curve. It is also found that the operating condition of occurrence of flow recirculation at impeller inlet is misestimated with k-ω and SST turbulence model. Furthermore, the original SST model has been modified. We predict the occurrence position of flow recirculation at impeller inlet correctly with the modified SST turbulence model, and it also can improve the prediction accuracy of the pump- turbine performance at the same time.

Robust fixed-time synchronization for uncertain complex-valued neural networks with discontinuous activation functions.

PubMed

Ding, Xiaoshuai; Cao, Jinde; Alsaedi, Ahmed; Alsaadi, Fuad E; Hayat, Tasawar

2017-06-01

This paper is concerned with the fixed-time synchronization for a class of complex-valued neural networks in the presence of discontinuous activation functions and parameter uncertainties. Fixed-time synchronization not only claims that the considered master-slave system realizes synchronization within a finite time segment, but also requires a uniform upper bound for such time intervals for all initial synchronization errors. To accomplish the target of fixed-time synchronization, a novel feedback control procedure is designed for the slave neural networks. By means of the Filippov discontinuity theories and Lyapunov stability theories, some sufficient conditions are established for the selection of control parameters to guarantee synchronization within a fixed time, while an upper bound of the settling time is acquired as well, which allows to be modulated to predefined values independently on initial conditions. Additionally, criteria of modified controller for assurance of fixed-time anti-synchronization are also derived for the same system. An example is included to illustrate the proposed methodologies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cultural Discontinuity: Toward a Quantitative Investigation of a Major Hypothesis in Education

ERIC Educational Resources Information Center

Tyler, Kenneth M.; Uqdah, Aesha L.; Dillihunt, Monica L.; Beatty-Hazelbaker, ReShanta; Conner, Timothy; Gadson, Nadia; Henchy, Alexandra; Hughes, Travonia; Mulder, Shambra; Owens, Elizabeth; Roan-Belle, Clarissa; Smith, LaToya; Stevens, Ruby

2008-01-01

Education researchers have suggested that the academic challenges faced by many ethnic minority students are linked to perceived cultural discontinuity between students' home- and school-based experiences. However, there has been very little empirical inquiry into the existence and effects of cultural discontinuity for these students. The purpose…

Effect of manufacturing defects on optical performance of discontinuous freeform lenses.

PubMed

Wang, Kai; Liu, Sheng; Chen, Fei; Liu, Zongyuan; Luo, Xiaobing

2009-03-30

Discontinuous freeform lens based secondary optics are essential to LED illumination systems. Surface roughness and smooth transition between two discrete sub-surfaces are two of the most common manufacturing defects existing in discontinuous freeform lenses. The effects of these two manufacturing defects on the optical performance of two discontinuous freeform lenses were investigated by comparing the experimental results with the numerical simulation results based on Monte Carlo ray trace method. The results demonstrated that manufacturing defects induced surface roughness had small effect on the light output efficiency and the shape of light pattern of the PMMA lens but significantly affected the uniformity of light pattern, which declined from 0.644 to 0.313. The smooth transition surfaces with deviation angle more than 60 degrees existing in the BK7 glass lens, not only reduced the uniformity of light pattern, but also reduced the light output efficiency from 96.9% to 91.0% and heavily deformed the shape of the light pattern. Comparing with the surface roughness, the smooth transition surface had a much more adverse effect on the optical performance of discontinuous freeform lenses. Three methods were suggested to improve the illumination performance according to the analysis and discussion.

Retro-regression--another important multivariate regression improvement.

PubMed

Randić, M

2001-01-01

We review the serious problem associated with instabilities of the coefficients of regression equations, referred to as the MRA (multivariate regression analysis) "nightmare of the first kind". This is manifested when in a stepwise regression a descriptor is included or excluded from a regression. The consequence is an unpredictable change of the coefficients of the descriptors that remain in the regression equation. We follow with consideration of an even more serious problem, referred to as the MRA "nightmare of the second kind", arising when optimal descriptors are selected from a large pool of descriptors. This process typically causes at different steps of the stepwise regression a replacement of several previously used descriptors by new ones. We describe a procedure that resolves these difficulties. The approach is illustrated on boiling points of nonanes which are considered (1) by using an ordered connectivity basis; (2) by using an ordering resulting from application of greedy algorithm; and (3) by using an ordering derived from an exhaustive search for optimal descriptors. A novel variant of multiple regression analysis, called retro-regression (RR), is outlined showing how it resolves the ambiguities associated with both "nightmares" of the first and the second kind of MRA.

Modified Regression Correlation Coefficient for Poisson Regression Model

NASA Astrophysics Data System (ADS)

Kaengthong, Nattacha; Domthong, Uthumporn

2017-09-01

This study gives attention to indicators in predictive power of the Generalized Linear Model (GLM) which are widely used; however, often having some restrictions. We are interested in regression correlation coefficient for a Poisson regression model. This is a measure of predictive power, and defined by the relationship between the dependent variable (Y) and the expected value of the dependent variable given the independent variables [E(Y|X)] for the Poisson regression model. The dependent variable is distributed as Poisson. The purpose of this research was modifying regression correlation coefficient for Poisson regression model. We also compare the proposed modified regression correlation coefficient with the traditional regression correlation coefficient in the case of two or more independent variables, and having multicollinearity in independent variables. The result shows that the proposed regression correlation coefficient is better than the traditional regression correlation coefficient based on Bias and the Root Mean Square Error (RMSE).

Scaffold optimization in discontinuous epitope containing protein mimics of gp120 using smart libraries.

PubMed

Mulder, Gwenn E; Quarles van Ufford, H Linda C; van Ameijde, Jeroen; Brouwer, Arwin J; Kruijtzer, John A W; Liskamp, Rob M J

2013-04-28

A diversity of protein surface discontinuous epitope mimics is now rapidly and efficiently accessible. Despite the important role of protein-protein interactions involving discontinuous epitopes in a wide range of diseases, mimicry of discontinuous epitopes using peptide-based molecules remains a major challenge. Using copper(I) catalyzed azide-alkyne cycloaddition (CuAAC), we have developed a general and efficient method for the synthesis of collections of discontinuous epitope mimics. Up to three different cyclic peptides, representing discontinuous epitopes in HIV-gp120, were conjugated to a selection of scaffold molecules. Variation of the scaffold molecule, optimization of the ring size of the cyclic peptides and screening of the resulting libraries for successful protein mimics led to an HIV gp120 mimic with an IC50 value of 1.7 μM. The approach described here provides rapid and highly reproducible access to clean, smart libraries of very complex bio-molecular constructs representing protein mimics for use as synthetic vaccines and beyond.