Science.gov

Sample records for component failure rates

  1. Saturn component failure rate and failure rate modifiers

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Failure mode frequency ratios, environmental adjustment factors, and failure rates for mechanical and electromechanical component families are presented. The failure rates and failure rate modifiers resulted from a series of studies whose purpose was to provide design, tests, reliability, and systems engineers with accurate, up-to-date failure rate information. The results of the studies were achieved through an extensive engineering analysis of the Saturn Program test data and Unsatisfactory Condition Reports (UCR's) and the application of mathematical techniques developed for the studies.

  2. Comparison of Tritium Component Failure Rate Data

    SciTech Connect

    Lee C. Cadwallader

    2004-09-01

    Published failure rate values from the US Tritium Systems Test Assembly, the Japanese Tritium Process Laboratory, the German Tritium Laboratory Karlsruhe, and the Joint European Torus Active Gas Handling System have been compared. This comparison is on a limited set of components, but there is a good variety of data sets in the comparison. The data compared reasonably well. The most reasonable failure rate values are recommended for use on next generation tritium handling system components, such as those in the tritium plant systems for the International Thermonuclear Experimental Reactor and the tritium fuel systems of inertial fusion facilities, such as the US National Ignition Facility. These data and the comparison results are also shared with the International Energy Agency cooperative task on fusion component failure rate data.

  3. Failure Rate Data Analysis for High Technology Components

    SciTech Connect

    L. C. Cadwallader

    2007-07-01

    Understanding component reliability helps designers create more robust future designs and supports efficient and cost-effective operations of existing machines. The accelerator community can leverage the commonality of its high-vacuum and high-power systems with those of the magnetic fusion community to gain access to a larger database of reliability data. Reliability studies performed under the auspices of the International Energy Agency are the result of an international working group, which has generated a component failure rate database for fusion experiment components. The initial database work harvested published data and now analyzes operating experience data. This paper discusses the usefulness of reliability data, describes the failure rate data collection and analysis effort, discusses reliability for components with scarce data, and points out some of the intersections between magnetic fusion experiments and accelerators.

  4. Selected component failure rate values from fusion safety assessment tasks

    SciTech Connect

    Cadwallader, L.C.

    1998-09-01

    This report is a compilation of component failure rate and repair rate values that can be used in magnetic fusion safety assessment tasks. Several safety systems are examined, such as gas cleanup systems and plasma shutdown systems. Vacuum system component reliability values, including large vacuum chambers, have been reviewed. Values for water cooling system components have also been reported here. The report concludes with the examination of some equipment important to personnel safety, atmospheres, combustible gases, and airborne releases of radioactivity. These data should be useful to system designers to calculate scoping values for the availability and repair intervals for their systems, and for probabilistic safety or risk analysts to assess fusion systems for safety of the public and the workers.

  5. Selected Component Failure Rate Values from Fusion Safety Assessment Tasks

    SciTech Connect

    Cadwallader, Lee Charles

    1998-09-01

    This report is a compilation of component failure rate and repair rate values that can be used in magnetic fusion safety assessment tasks. Several safety systems are examined, such as gas cleanup systems and plasma shutdown systems. Vacuum system component reliability values, including large vacuum chambers, have been reviewed. Values for water cooling system components have also been reported here. The report concludes with the examination of some equipment important to personnel safety, atmospheres, combustible gases, and airborne releases of radioactivity. These data should be useful to system designers to calculate scoping values for the availability and repair intervals for their systems, and for probabilistic safety or risk analysts to assess fusion systems for safety of the public and the workers.

  6. Component Failure Rate Data Sources for Probabilistic Safety and Reliability

    SciTech Connect

    L. C. Cadwallader; S. A. Eide

    2010-09-01

    Probabilistic safety methods are being used in several industries, including chemical, manufacturing, and energy. When performing reliability studies or using probabilistic safety approaches, a basic need arises for input data on failure rates of the mechanical, electrical, instrumentation and control, and other components that comprise the engineering systems in the facility. Some companies have many types of data stored and can retrieve these in-house data for such uses. Other companies hire consultants to perform safety assessments; the consulting firms often use their own data bases. For those analysts who do not have either of those options available, this paper presents some data sources that are retrievable from the literature. These data sources have been evaluated with a basic rating of usefulness for analysis work, and each has a description of what data can be found in the citation that can be used to support assessments in industry. The accessibility of data documents via the internet is also described.

  7. Estimation procedures to measure and monitor failure rates of components during thermal-vacuum testing

    NASA Technical Reports Server (NTRS)

    Williams, R. E.; Kruger, R.

    1980-01-01

    Estimation procedures are described for measuring component failure rates, for comparing the failure rates of two different groups of components, and for formulating confidence intervals for testing hypotheses (based on failure rates) that the two groups perform similarly or differently. Appendix A contains an example of an analysis in which these methods are applied to investigate the characteristics of two groups of spacecraft components. The estimation procedures are adaptable to system level testing and to monitoring failure characteristics in orbit.

  8. ESTIMATION OF FAILURE RATES OF DIGITAL COMPONENTS USING A HIERARCHICAL BAYESIAN METHOD.

    SciTech Connect

    YUE, M.; CHU, T.L.

    2006-01-30

    One of the greatest challenges in evaluating reliability of digital I&C systems is how to obtain better failure rate estimates of digital components. A common practice of the digital component failure rate estimation is attempting to use empirical formulae to capture the impacts of various factors on the failure rates. The applicability of an empirical formula is questionable because it is not based on laws of physics and requires good data, which is scarce in general. In this study, the concept of population variability of the Hierarchical Bayesian Method (HBM) is applied to estimating the failure rate of a digital component using available data. Markov Chain Monte Carlo (MCMC) simulation is used to implement the HBM. Results are analyzed and compared by selecting different distribution types and priors distributions. Inspired by the sensitivity calculations and based on review of analytic derivations, it seems reasonable to suggest avoiding the use of gamma distribution in two-stage Bayesian analysis and HBM analysis.

  9. Investigation of component failure rates for pulsed versus steady state tokamak operation

    SciTech Connect

    Cadwallader, L.C.

    1992-07-01

    This report presents component failure rate data sources applicable to magnetic fusion systems, and defines multiplicative factors to adjust these data for specific use on magnetic fusion experiment designs. The multipliers address both long pulse and steady state tokamak operation. Thermal fatigue and radiation damage are among the leading reasons for large multiplier values in pulsed operation applications. Field failure rate values for graphite protective tiles are presented, and beryllium tile failure rates in laboratory testing are also given. All of these data can be used for reliability studies, safety analyses, design tradeoff studies, and risk assessments.

  10. Component failure-rate data with potential applicability to the hot experimental facility. Technical information

    SciTech Connect

    Dexter, A.H.

    1980-12-01

    A literature search, that was aided by computer searches of a number of data bases, resulted in the compilation of approximately 1223 pieces of component failure-rate data under 136 subject categories. The data bank can be provided upon request as a punched-card deck or on magnetic tape.

  11. Component failure data handbook

    SciTech Connect

    Gentillon, C.D.

    1991-04-01

    This report presents generic component failure rates that are used in reliability and risk studies of commercial nuclear power plants. The rates are computed using plant-specific data from published probabilistic risk assessments supplemented by selected other sources. Each data source is described. For rates with four or more separate estimates among the sources, plots show the data that are combined. The method for combining data from different sources is presented. The resulting aggregated rates are listed with upper bounds that reflect the variability observed in each rate across the nuclear power plant industry. Thus, the rates are generic. Both per hour and per demand rates are included. They may be used for screening in risk assessments or for forming distributions to be updated with plant-specific data.

  12. Correlation study between vibrational environmental and failure rates of civil helicopter components

    NASA Technical Reports Server (NTRS)

    Alaniz, O.

    1979-01-01

    An investigation of two selected helicopter types, namely, the Models 206A/B and 212, is reported. An analysis of the available vibration and reliability data for these two helicopter types resulted in the selection of ten components located in five different areas of the helicopter and consisting primarily of instruments, electrical components, and other noncritical flight hardware. The potential for advanced technology in suppressing vibration in helicopters was assessed. The are still several unknowns concerning both the vibration environment and the reliability of helicopter noncritical flight components. Vibration data for the selected components were either insufficient or inappropriate. The maintenance data examined for the selected components were inappropriate due to variations in failure mode identification, inconsistent reporting, or inaccurate informaton.

  13. GAMMA: a code for the analysis of component failure rates with a compound Poisson-gamma model. Final technical report

    SciTech Connect

    Shultis, J.K.; Johnson, D.E.; Milliken, G.A.; Eckhoff, N.D.

    1981-12-01

    The theory is summarized for the homogeneous Poisson and the compound gamma-Poisson probability models which can be used to analyze failure rate attribute data consisting of the number of failures in specified test times for normally operating components or systems. A computer code based on this theory is described, and instructions for its use together with a sample problem and a complete code listing are presented. For the compound model, used in a Bayesian analysis of failure rate data, values of the parameters for the prior gamma distribution, chosen a priori, are estimated from observed failure data by three methods: (1) matching the data moments to those of the prior distribution, (2) matching the data moments to those of the marginal distribution, and (3) the marginal maximum likelihood method. Many program options are available including variance estimates for the prior parameter estimators, posteriori analyses for each component, various statistical comparisons between the homogeneous and compound models, and generalized chi-square and Kolmogorov-Smirnov goodness-of-fit tests for determining how well the failure models describe the observed data.

  14. Component failure data handbook. Technical evaluation report

    SciTech Connect

    Gentillon, C.D.

    1991-04-01

    This report presents generic component failure rates that are used in reliability and risk studies of commercial nuclear power plants. The rates are computed using plant-specific data from published probabilistic risk assessments supplemented by selected other sources. Each data source is described. For rates with four or more separate estimates among the sources, plots show the data that are combined. The method for combining data from different sources is presented. The resulting aggregated rates are listed with upper bounds that reflect the variability observed in each rate across the nuclear power plant industry. Thus, the rates are generic. Both per hour and per demand rates are included. They may be used for screening in risk assessments or for forming distributions to be updated with plant-specific data.

  15. A PROPOSED METHOD FOR ESTIMATING FAILURE RATES OF DEGRADED PASSIVE COMPONENTS IN THE NRC SIGNIFICANCE DETERMINATION PROCESS

    SciTech Connect

    Unwin, Stephen D.; Johnson, Kenneth I.; Ivans, William J.; Lowry, Peter P.

    2013-11-01

    This paper outlines a methodology for estimation of the incremental core damage frequency associated with the degradation of passive components with a view to its application in the US Nuclear Regulatory Commission's significance determination process. The method involves use of simplified physics-based models of materials degradation and the probabilistic comparison of transient loads with deteriorating system capacities.

  16. Failure Analysis of Ceramic Components

    SciTech Connect

    B.W. Morris

    2000-06-29

    Ceramics are being considered for a wide range of structural applications due to their low density and their ability to retain strength at high temperatures. The inherent brittleness of monolithic ceramics requires a departure from the deterministic design philosophy utilized to analyze metallic structural components. The design program ''Ceramic Analysis and Reliability Evaluation of Structures Life'' (CARES/LIFE) developed by NASA Lewis Research Center uses a probabilistic approach to predict the reliability of monolithic components under operational loading. The objective of this study was to develop an understanding of the theories used by CARES/LIFE to predict the reliability of ceramic components and to assess the ability of CARES/LIFE to accurately predict the fast fracture behavior of monolithic ceramic components. A finite element analysis was performed to determine the temperature and stress distribution of a silicon carbide O-ring under diametral compression. The results of the finite element analysis were supplied as input into CARES/LIFE to determine the fast fracture reliability of the O-ring. Statistical material strength parameters were calculated from four-point flexure bar test data. The predicted reliability showed excellent correlation with O-ring compression test data indicating that the CARES/LIFE program can be used to predict the reliability of ceramic components subjected to complicated stress states using material properties determined from simple uniaxial tensile tests.

  17. Development of Nonelectronic Part Cyclic Failure Rates

    DTIC Science & Technology

    1977-12-01

    for a short duration. The dc operation allows the current to build up to rated value during energization with no overshoot. Protective devices, such...failures/ houL 4.3 Part Classes and Failure Rates To update Sections 2.9, 2.10, and 2.11 of MIL-HDBK-217B, failure rate mathematical models and base

  18. GENERIC, COMPONENT FAILURE DATA BASE FOR LIGHT WATER AND LIQUID SODIUM REACTOR PRAs

    SciTech Connect

    S. A. Eide; S. V. Chmielewski; T. D. Swantz

    1990-02-01

    A comprehensive generic component failure data base has been developed for light water and liquid sodium reactor probabilistic risk assessments (PRAs) . The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and the Centralized Reliability Data Organization (CREDO) data bases were used to generate component failure rates . Using this approach, most of the failure rates are based on actual plant data rather than existing estimates .

  19. Tritium Waste Treatment System component failure data analysis from June 18, 1984--December 31, 1989

    SciTech Connect

    Cadwallader, L.C. ); Stolpe Gavett, M.A. )

    1990-09-01

    This document gives the failure rates for the major tritium-bearing components in the Tritium Waste Treatment System at the Tritium Systems Test Assembly, which is a fusion research and technology facility at the Los Alamos National Laboratory. The failure reports, component populations, and operating demands/hours are given in this report, and sample calculations for binomial demand failure rates and poisson hourly failure rates are given in the appendices. The failure rates for tritium-bearing components were on the order of the screening failure rate values suggested for fusion reliability and risk analyses. More effort should be directed toward collecting and analyzing fusion component failure data, since accurate failure rates are necessary to refine reliability and risk analyses. 15 refs., 4 figs., 4 tabs.

  20. Idaho Chemical Processing Plant failure rate database

    SciTech Connect

    Alber, T.G.; Hunt, C.R.; Fogarty, S.P.; Wilson, J.R.

    1995-08-01

    This report represents the first major upgrade to the Idaho Chemical Processing Plant (ICPP) Failure Rate Database. This upgrade incorporates additional site-specific and generic data while improving on the previous data reduction techniques. In addition, due to a change in mission at the ICPP, the status of certain equipment items has changed from operating to standby or off-line. A discussion of how this mission change influenced the relevance of failure data also has been included. This report contains two data sources: the ICPP Failure Rate Database and a generic failure rate database. A discussion is presented on the approaches and assumptions used to develop the data in the ICPP Failure Rate Database. The generic database is included along with a short discussion of its application. A brief discussion of future projects recommended to strengthen and lend credibility to the ICPP Failure Rate Database also is included.

  1. Statistical relation between single- and multiple-component failures

    SciTech Connect

    Teichmann, T.; Papazoglou, I.A.

    1982-01-01

    This paper describes the results of some investigations of the statistical (and to some degree the qualitative) relation between single and multiple component failure events at US operating nuclear plants. The objectives of the investigations were to establish whether: multiple component failures could be attributed to random coincidences of single independent failures; there was any clear cut qualitative connection between the two type of failures; and there were any quantitative statistical parameters that related the two types of failure.

  2. Study on failure analysis of array chip components in IRFPA

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaonan; He, Yingjie; Li, Jinping

    2016-10-01

    Infrared focal plane array detector has advantages of strong anti-interference ability and high sensitivity. Its size, weight and power dissipation has been noticeably decreased compared to the conventional infrared imaging system. With the development of the detector manufacture technology and the cost reduction, IRFPA detector has been widely used in the military and commercial fields. Due to the restricting of array chip manufacturing process and material defects, the fault phenomenon such as cracking, bad pixel and abnormal output was showed during the test, which restricts the performance of the infrared detector imaging system, and these effects are gradually intensified with the expanding of the focal plane array size and the shrinking of the pixel size. Based on the analysis of the test results for the infrared detector array chip components, the fault phenomenon was classified. The main cause of the chip component failure is chip cracking, bad pixel and abnormal output. The reason of the failure has been analyzed deeply. According to analyze the mechanism of the failure, a series of measures which contain filtrating materials and optimizing the manufacturing process of array chip components were used to improve the performance of the chip components and the test pass rate, which is used to meet the needs of the detector performance.

  3. Secondary Containment System component failure data analysis from 1984 to 1991

    SciTech Connect

    Cadwallader, L.C. ); Sanchez, D.P. )

    1992-08-01

    This report gives the failure rates for the major tritium containing glovebox systems that comprise the Secondary Containment System at the Tritium systems Test Assembly, which is a fusion research and technology facility at the Los Alamos National Laboratory. The component failure reports, the numbers of components, and operating times or demands are all given in this report, and sample calculations of the binomial demand failure rates and poisson hourly failure rates are given in the appendices. The failure rates for these components form a solid data point based on actual operating experience, where there is very little published information. The eight years of nearly continuous Secondary Containment System operations should result in steady state failure rate values. These data should be useful for future fusion reactor design work and safety assessment tasks.

  4. SCADA alarms processing for wind turbine component failure detection

    NASA Astrophysics Data System (ADS)

    Gonzalez, E.; Reder, M.; Melero, J. J.

    2016-09-01

    Wind turbine failure and downtime can often compromise the profitability of a wind farm due to their high impact on the operation and maintenance (O&M) costs. Early detection of failures can facilitate the changeover from corrective maintenance towards a predictive approach. This paper presents a cost-effective methodology to combine various alarm analysis techniques, using data from the Supervisory Control and Data Acquisition (SCADA) system, in order to detect component failures. The approach categorises the alarms according to a reviewed taxonomy, turning overwhelming data into valuable information to assess component status. Then, different alarms analysis techniques are applied for two purposes: the evaluation of the SCADA alarm system capability to detect failures, and the investigation of the relation between components faults being followed by failure occurrences in others. Various case studies are presented and discussed. The study highlights the relationship between faulty behaviour in different components and between failures and adverse environmental conditions.

  5. Using Dynamic Master Logic Diagram for component partial failure analysis

    SciTech Connect

    Ni, T.; Modarres, M.

    1996-12-01

    A methodology using the Dynamic Master Logic Diagram (DMLD) for the evaluation of component partial failure is presented. Since past PRAs have not focused on partial failure effects, the reliability of components are only based on the binary state assumption, i.e. defining a component as fully failed or functioning. This paper is to develop an approach to predict and estimate the component partial failure on the basis of the fuzzy state assumption. One example of the application of this methodology with the reliability function diagram of a centrifugal pump is presented.

  6. Stochastic Models for Common Failures of Components.

    DTIC Science & Technology

    1984-03-01

    common cause model, NUREG /CR-1401, 1980. [3] Church, J. D. and Harris, B., The estimation of reliability from stress- strength relationship...Fachband 2/1, 1980. [11] Lewis, H. W., Chairman, Risk Assessment Review Group Report to the U. S. Nuclear Regulatory Commission, NUREG /CR-0400, 1978. [12...Regulatory Commission, P.R.A. Procedures Guide, NUREG / CR-2300, 1983. [18] Vesely, W. E., Estimating Common Cause Failure Probabilities in Reliability and

  7. Acute Failure of a Glenoid Component in Anatomic Shoulder Arthroplasty

    PubMed Central

    Boardman, III, Norman D.

    2016-01-01

    Glenoid loosening is the most common cause of failure in primary total shoulder arthroplasty (TSA) and often occurs years after the initial surgery. It is rare for a glenoid component to fail acutely. Several case reports of complete glenoid dissociation appear in the literature. It is important to report these failures to identify technical errors or component design flaws to improve outcomes in TSA. In this case report, we present an unrecognized acute failure of a cemented hybrid glenoid component at the time of surgery. PMID:27555976

  8. Component criticality in failure cascade processes of network systems.

    PubMed

    Zio, Enrico; Sansavini, Giovanni

    2011-08-01

    In this work, specific indicators are used to characterize the criticality of components in a network system with respect to their contribution to failure cascade processes. A realistic-size network is considered as reference case study. Three different models of cascading failures are analyzed, differing both on the failure load distribution logic and on the cascade triggering event. The criticality indicators are compared to classical measures of topological centrality to identify the one most characteristic of the cascade processes considered.

  9. Solder Reflow Failures in Electronic Components During Manual Soldering

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander; Greenwell, Chris; Felt, Frederick

    2008-01-01

    This viewgraph presentation reviews the solder reflow failures in electronic components that occur during manual soldering. It discusses the specifics of manual-soldering-induced failures in plastic devices with internal solder joints. The failure analysis turned up that molten solder had squeezed up to the die surface along the die molding compound interface, and the dice were not protected with glassivation allowing solder to short gate and source to the drain contact. The failure analysis concluded that the parts failed due to overheating during manual soldering.

  10. Cyclic plasticity and failure of structural components

    NASA Technical Reports Server (NTRS)

    Kalev, I.

    1980-01-01

    An analytical approach for low-cycle fatigue prediction is presented. The approach combines a cyclic plasticity model with the finite element method and a damage accumulation criterion for ductile metals. The cyclic plasticity model is based on the concept of the combination of several yield surfaces. The surfaces are related to the material uniaxial stress-strain curve idealized by piecewise linear segments. The damage criterion is based on the Coffin-Manson formulae modified for the mean stress variation effect. It is extended to the multiaxial varying stress-strain field and applied for both the crack initiation and the crack growth processes. The stable slow crack growth rate is approximated by the damage accumulation gradient computed from the cracked finite element models. This procedure requires fatigue testing data of only smooth specimens under constant strain amplitudes. The present approach is illustrated by numerical examples of an aircraft wing stiffened panel subjected to compression, which causes material yielding and residual tension.

  11. Microcircuit Device Reliability. Digital Failure Rate Data

    DTIC Science & Technology

    1981-01-01

    dfc ^MlM "" ■ ’’ •""" DIGITAL DEVICE DATA VARIOUS TTL t MANUFACTURER OPERATIONAL TYPE RELIABILITt ANALYSIS...Analysis Center I $ ^: io Microcircuit Device Reliability DIGITAL FAILURE RATE DATA t - D D Summer 1981 Prepared by: Reliability Analysis...Approved for Public Release, Distribution Unlimited .. .11 ■■’■’■’■.■^"■i;>;->k:.v.v^-:.-.,-,->■’^ ■.■»[ >** T *»,*-’,>;’ * ’^ ■ t , ■ A

  12. Deriving Function-failure Similarity Information for Failure-free Rotorcraft Component Design

    NASA Technical Reports Server (NTRS)

    Roberts, Rory A.; Stone, Robert B.; Tumer, Irem Y.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Performance and safety are the top concerns of high-risk aerospace applications at NASA. Eliminating or reducing performance and safety problems can be achieved with a thorough understanding of potential failure modes in the design that lead to these problems. The majority of techniques use prior knowledge and experience as well as Failure Modes and Effects as methods to determine potential failure modes of aircraft. The aircraft design needs to be passed through a general technique to ensure that every potential failure mode is considered, while avoiding spending time on improbable failure modes. In this work, this is accomplished by mapping failure modes to certain components, which are described by their functionality. In turn, the failure modes are then linked to the basic functions that are carried within the components of the aircraft. Using the technique proposed in this paper, designers can examine the basic functions, and select appropriate analyses to eliminate or design out the potential failure modes. This method was previously applied to a simple rotating machine test rig with basic functions that are common to a rotorcraft. In this paper, this technique is applied to the engine and power train of a rotorcraft, using failures and functions obtained from accident reports and engineering drawings.

  13. Assessment of hoist failure rate for Payload Transporter III

    SciTech Connect

    Demmie, P.N.

    1994-02-01

    Assessment of the hoist failure rate for the Payload Transporter Type III (PT-III) hoist was completed as one of the ground transportation tasks for the Minuteman II (MMIII) Weapon System Safety Assessment. The failures of concern are failures that lead to dropping a reentry system (RS) during hoist operations in a silo or the assembly, storage, and inspection building for a MMIII wing. After providing a brief description of the PT-III hoist system, the author summarizes his search for historical data from industry and the military services for failures of electric hoist systems. Since such information was not found, the strategy for assessing a failure rate was to consider failure mechanisms which lead to load-drop accidents, estimate their rates, and sum the rates for the PT-III hoist failure rate. The author discusses failure mechanisms and describes his assessment of a chain failure rate that is based on data from destructive testing of a chain of the type used for the PT-III hoist and projected usage rates for hoist operations involving the RS. The main result provides upper bounds for chain failure rates that are based on these data. No test data were found to estimate failure rates due to mechanisms other than chain failure. The author did not attempt to quantify the effects of human factors on the PT-III hoist failure rate.

  14. Effect of Component Failures on Economics of Distributed Photovoltaic Systems

    SciTech Connect

    Lubin, Barry T.

    2012-02-02

    This report describes an applied research program to assess the realistic costs of grid connected photovoltaic (PV) installations. A Board of Advisors was assembled that included management from the regional electric power utilities, as well as other participants from companies that work in the electric power industry. Although the program started with the intention of addressing effective load carrying capacity (ELCC) for utility-owned photovoltaic installations, results from the literature study and recommendations from the Board of Advisors led investigators to the conclusion that obtaining effective data for this analysis would be difficult, if not impossible. The effort was then re-focused on assessing the realistic costs and economic valuations of grid-connected PV installations. The 17 kW PV installation on the University of Hartford's Lincoln Theater was used as one source of actual data. The change in objective required a more technically oriented group. The re-organized working group (changes made due to the need for more technically oriented participants) made site visits to medium-sized PV installations in Connecticut with the objective of developing sources of operating histories. An extensive literature review helped to focus efforts in several technical and economic subjects. The objective of determining the consequences of component failures on both generation and economic returns required three analyses. The first was a Monte-Carlo-based simulation model for failure occurrences and the resulting downtime. Published failure data, though limited, was used to verify the results. A second model was developed to predict the reduction in or loss of electrical generation related to the downtime due to these failures. Finally, a comprehensive economic analysis, including these failures, was developed to determine realistic net present values of installed PV arrays. Two types of societal benefits were explored, with quantitative valuations developed for

  15. Product component genealogy modeling and field-failure prediction

    SciTech Connect

    King, Caleb; Hong, Yili; Meeker, William Q.

    2016-04-13

    Many industrial products consist of multiple components that are necessary for system operation. There is an abundance of literature on modeling the lifetime of such components through competing risks models. During the life-cycle of a product, it is common for there to be incremental design changes to improve reliability, to reduce costs, or due to changes in availability of certain part numbers. These changes can affect product reliability but are often ignored in system lifetime modeling. By incorporating this information about changes in part numbers over time (information that is readily available in most production databases), better accuracy can be achieved in predicting time to failure, thus yielding more accurate field-failure predictions. This paper presents methods for estimating parameters and predictions for this generational model and a comparison with existing methods through the use of simulation. Our results indicate that the generational model has important practical advantages and outperforms the existing methods in predicting field failures.

  16. Completely monotone regression estimates of software failure rates

    NASA Technical Reports Server (NTRS)

    Miller, D. R.; Sofer, A.

    1985-01-01

    A method for estimating the present failure rate of a program is presented. A crude nonparameter estimate of the failure rate function is obtained from past failure times. This estimate is then smoothed by fitting a completely monotonic function, which is the solution of a quadratic programming problem. The value of the smoothed function at present time is used as the estimate of present failure rate. Results of a Monte Carlo study of performance are given.

  17. Reduction of LNG operator error and equipment failure rates. Topical report, 20 April 1990

    SciTech Connect

    Atallah, S.; Shah, J.N.; Betti, M.

    1990-04-01

    Tables summarizing human error rates and equipment failure frequencies applicable to the LNG industry are presented. Improved training, better supervision, emergency response drills and improved panel design were methods recommended for reducing human error rates. Outright scheduled replacement of critical components, regular inspection and maintenance, and the use of redundant components were reviewed as means for reducing equipment failure rates. The effect of reducing human error and equipment failure rates on the frequency of overfilling an LNG tank were examined. In addition, guidelines for estimating the cost and benefits of these mitigation measures were considered.

  18. Failures Of CMOS Devices At Low Radiation-Dose Rates

    NASA Technical Reports Server (NTRS)

    Goben, Charles A.; Price, William E.

    1990-01-01

    Method for obtaining approximate failure-versus-dose-rate curves derived from experiments on failures of SGS 4007 complementary metal oxide/semiconductor (CMOS) integrated circuits irradiated by Co60 and Cs137 radioactive sources.

  19. Assessing Wind Farm Reliability Using Weather Dependent Failure Rates

    NASA Astrophysics Data System (ADS)

    Wilson, G.; McMillan, D.

    2014-06-01

    Using reliability data comprising of two modern, large scale wind farm sites and wind data from two onsite met masts, a model is developed which calculates wind speed dependant failure rates which are used to populate a Markov Chain. Monte Carlo simulation is then exercised to simulate three wind farms which are subjected to controlled wind speed conditions from three separate potential UK sites. The model then calculates and compares wind farm reliability due to corrective maintenance and component failure rates influenced by the wind speed of each of the sites. Results show that the components affected most by changes in average daily wind speed are the control system and the yaw system. A comparison between this model and a more simple estimation of site yield is undertaken. The model takes into account the effects of the wind speed on the cost of operation and maintenance and also includes the impact of longer periods of downtime in the winter months and shorter periods in the summer. By taking these factors into account a more detailed site assessment can be undertaken. There is significant value to this model for operators and manufacturers.

  20. Product component genealogy modeling and field-failure prediction

    DOE PAGES

    King, Caleb; Hong, Yili; Meeker, William Q.

    2016-04-13

    Many industrial products consist of multiple components that are necessary for system operation. There is an abundance of literature on modeling the lifetime of such components through competing risks models. During the life-cycle of a product, it is common for there to be incremental design changes to improve reliability, to reduce costs, or due to changes in availability of certain part numbers. These changes can affect product reliability but are often ignored in system lifetime modeling. By incorporating this information about changes in part numbers over time (information that is readily available in most production databases), better accuracy can bemore » achieved in predicting time to failure, thus yielding more accurate field-failure predictions. This paper presents methods for estimating parameters and predictions for this generational model and a comparison with existing methods through the use of simulation. Our results indicate that the generational model has important practical advantages and outperforms the existing methods in predicting field failures.« less

  1. Heartbeat Model for Component Failure in Simulation of Plant Behavior

    SciTech Connect

    R. W. Youngblood; R. R. Nourgaliev; D. L. Kelly; C. L. Smith; T-N. Dinh

    2011-03-01

    As part of the Department of Energy’s “Light Water Reactor Sustainability Program” (LWRSP), tools and methodology for risk-informed characterization of safety margin are being developed for use in supporting decision-making on plant life extension after the first license renewal. Beginning with the traditional discussion of “margin” in terms of a “load” (a physical challenge to system or component function) and a “capacity” (the capability of that system or component to accommodate the challenge), we are developing the capability to characterize realistic probabilistic load and capacity spectra, reflecting both aleatory and epistemic uncertainty in system behavior. This way of thinking about margin comports with work done in the last 10 years. However, current capabilities to model in this way are limited: it is currently possible, but difficult, to validly simulate enough time histories to support quantification in realistic problems, and the treatment of environmental influences on reliability is relatively artificial in many existing applications. The INL is working on a next-generation safety analysis capability (widely referred to as “R7”) that will enable a much better integration of reliability-related and phenomenology-related aspects of margin. In this paper, we show how to implement cumulative damage (“heartbeat”) models for component reliability that lend themselves naturally to being included as part of the phenomenology simulation. Implementation of this modeling approach relies on the way in which the phenomenology simulation implements its dynamic time step management. Within this approach, component failures influence the phenomenology, and the phenomenology influences the component failures.

  2. Catastrophic failure of a low profile metal-backed glenoid component after total shoulder arthroplasty

    PubMed Central

    Vuillermin, Carley B.; Trump, Mark E.; Barwood, Shane A.; Hoy, Gregory A.

    2015-01-01

    Context: The longevity of the glenoid component in total shoulder arthroplasty (TSA) continues to be problematic. All polyethylene glenoid components have been most widely used, but loosening rates with time and the need for revision has resulted in high-profile metal-backed components with the potential for a more stable prosthesis bone interface and liner exchange. High revision rates in the high profile metal backed designs led us to evaluate a low profile metal backed component. Aims: To examine the rate and mode of failure of a TSA in a single surgeon consecutive series that has been identified by the Australian National Joint Replacement Registry to have a higher than anticipated rate of revision. Materials and Methods: This is a single surgeon retrospective consecutive series of 51 arthroplasties undertaken in 50 patients (18 males and 32 females) with an average age of 70.4 ears (range 51-90) and mean follow-up of 5.5 years (range 3.7-8.1). Results: We observed a very high (29%) rate of revision of the metal-backed glenoid components in this series. The primary mode of failure was glenoid baseplate nonintegration which with a well-fixed central cage screw led to bone resorption and implant breakage or disassembly. Conclusion: Analysis of the mode of failure of implants identified by robust registries is essential for the development of new prostheses and the pursuit of prosthesis longevity. This low profile metal backed prosthesis has been withdrawn, but without a published mechanism of failure. We feel that any prosthesis withdrawal should be accompanied by appropriate published mechanisms to prevent future component design errors based on similar design problems. PMID:26622128

  3. Component Labeling Algorithm For Video Rate Processing

    NASA Astrophysics Data System (ADS)

    Gotoh, Toshiyuki; Ohta, Yoshiyuki; Yoshida, Masumi; Shirai, Yoshio

    1987-10-01

    In this paper, we propose a raster scanning algorithm for component labeling, which enables processing under pipeline architecture. In the raster scanning algorithm, labels are provisionally assigned to each pixel of components and, at the same time, the connectivities of labels are detected at first scan. Those labels are classified into groups based on the connectivities. Finally provisional labels are updated using the result of classification and a unique label is assigned to each pixel of components. However, in the conventional algorithm, the classification process needs a vast number of operations. This prevents realizing pipeline processing. We have developed a method of preprocessing to reduce the number of provisional labels, which limits the number of label connectivities. We have also developed a new classification method whose operation is proportionate to only the number of label connectivities itself. We have made experiments with computer simulation to verify this algorithm. The experimental results show that we can process 512 x 512 x 8 bit images at video rate(1/30 sec. per 1 image) when this algorithm is implemented on hardware.

  4. Spacecraft Parachute Recovery System Testing from a Failure Rate Perspective

    NASA Technical Reports Server (NTRS)

    Stewart, Christine E.

    2013-01-01

    Spacecraft parachute recovery systems, especially those with a parachute cluster, require testing to identify and reduce failures. This is especially important when the spacecraft in question is human-rated. Due to the recent effort to make spaceflight affordable, the importance of determining a minimum requirement for testing has increased. The number of tests required to achieve a mature design, with a relatively constant failure rate, can be estimated from a review of previous complex spacecraft recovery systems. Examination of the Apollo parachute testing and the Shuttle Solid Rocket Booster recovery chute system operation will clarify at which point in those programs the system reached maturity. This examination will also clarify the risks inherent in not performing a sufficient number of tests prior to operation with humans on-board. When looking at complex parachute systems used in spaceflight landing systems, a pattern begins to emerge regarding the need for a minimum amount of testing required to wring out the failure modes and reduce the failure rate of the parachute system to an acceptable level for human spaceflight. Not only a sufficient number of system level testing, but also the ability to update the design as failure modes are found is required to drive the failure rate of the system down to an acceptable level. In addition, sufficient data and images are necessary to identify incipient failure modes or to identify failure causes when a system failure occurs. In order to demonstrate the need for sufficient system level testing prior to an acceptable failure rate, the Apollo Earth Landing System (ELS) test program and the Shuttle Solid Rocket Booster Recovery System failure history will be examined, as well as some experiences in the Orion Capsule Parachute Assembly System will be noted.

  5. Proportional and scale change models to project failures of mechanical components with applications to space station

    NASA Technical Reports Server (NTRS)

    Taneja, Vidya S.

    1996-01-01

    In this paper we develop the mathematical theory of proportional and scale change models to perform reliability analysis. The results obtained will be applied for the Reaction Control System (RCS) thruster valves on an orbiter. With the advent of extended EVA's associated with PROX OPS (ISSA & MIR), and docking, the loss of a thruster valve now takes on an expanded safety significance. Previous studies assume a homogeneous population of components with each component having the same failure rate. However, as various components experience different stresses and are exposed to different environments, their failure rates change with time. In this paper we model the reliability of a thruster valves by treating these valves as a censored repairable system. The model for each valve will take the form of a nonhomogeneous process with the intensity function that is either treated as a proportional hazard model, or a scale change random effects hazard model. Each component has an associated z, an independent realization of the random variable Z from a distribution G(z). This unobserved quantity z can be used to describe heterogeneity systematically. For various models methods for estimating the model parameters using censored data will be developed. Available field data (from previously flown flights) is from non-renewable systems. The estimated failure rate using such data will need to be modified for renewable systems such as thruster valve.

  6. Markov and semi-Markov processes as a failure rate

    NASA Astrophysics Data System (ADS)

    Grabski, Franciszek

    2016-06-01

    In this paper the reliability function is defined by the stochastic failure rate process with a non negative and right continuous trajectories. Equations for the conditional reliability functions of an object, under assumption that the failure rate is a semi-Markov process with an at most countable state space are derived. A proper theorem is presented. The linear systems of equations for the appropriate Laplace transforms allow to find the reliability functions for the alternating, the Poisson and the Furry-Yule failure rate processes.

  7. Markov and semi-Markov processes as a failure rate

    SciTech Connect

    Grabski, Franciszek

    2016-06-08

    In this paper the reliability function is defined by the stochastic failure rate process with a non negative and right continuous trajectories. Equations for the conditional reliability functions of an object, under assumption that the failure rate is a semi-Markov process with an at most countable state space are derived. A proper theorem is presented. The linear systems of equations for the appropriate Laplace transforms allow to find the reliability functions for the alternating, the Poisson and the Furry-Yule failure rate processes.

  8. Cascading failures in interdependent networks with finite functional components.

    PubMed

    Di Muro, M A; Buldyrev, S V; Stanley, H E; Braunstein, L A

    2016-10-01

    We present a cascading failure model of two interdependent networks in which functional nodes belong to components of size greater than or equal to s. We find theoretically and via simulation that in complex networks with random dependency links the transition is first order for s≥3 and continuous for s=2. We also study interdependent lattices with a distance constraint r in the dependency links and find that increasing r moves the system from a regime without a phase transition to one with a second-order transition. As r continues to increase, the system collapses in a first-order transition. Each regime is associated with a different structure of domain formation of functional nodes.

  9. Cascading failures in interdependent networks with finite functional components

    NASA Astrophysics Data System (ADS)

    Di Muro, M. A.; Buldyrev, S. V.; Stanley, H. E.; Braunstein, L. A.

    2016-10-01

    We present a cascading failure model of two interdependent networks in which functional nodes belong to components of size greater than or equal to s . We find theoretically and via simulation that in complex networks with random dependency links the transition is first order for s ≥3 and continuous for s =2 . We also study interdependent lattices with a distance constraint r in the dependency links and find that increasing r moves the system from a regime without a phase transition to one with a second-order transition. As r continues to increase, the system collapses in a first-order transition. Each regime is associated with a different structure of domain formation of functional nodes.

  10. The research on aging failure rate and optimization estimation of protective relay under haze conditions

    NASA Astrophysics Data System (ADS)

    Wang, Ying-kang; Zhou, Meng-ran; Yang, Jie; Zhou, Pei-qiang; Xie, Ying

    2017-01-01

    In the fog and haze, the air contains large amounts of H2S, SO2, SO3 and other acids, air conductivity is greatly improved, the relative humidity is also greatly increased, Power transmission lines and electrical equipment in such an environment will increase in the long-running failure ratedecrease the sensitivity of the detection equipment, impact protection device reliability. Weibull distribution is widely used in component failure distribution fitting. It proposes a protection device aging failure rate estimation method based on the least squares method and the iterative method,.Combined with a regional power grid statistics, computing protective equipment failure rate function. Binding characteristics of electrical equipment operation status under haze conditions, optimization methods, get more in line with aging protection equipment failure under conditions of haze characteristics.

  11. Ventricular rate control of atrial fibrillation in heart failure.

    PubMed

    Rienstra, Michiel; Van Gelder, Isabelle C

    2013-10-01

    In the last few years, there has been a major shift in the treatment of atrial fibrillation (AF) in the setting of hear failure (HF), from rhythm to ventricular rate control in most patients with both conditions. In this article, the authors focus on ventricular rate control and discuss the indications; the optimal ventricular rate-control target, including detailed results of the Rate Control Efficacy in Permanent Atrial Fibrillation: a Comparison Between Lenient versus Strict Rate Control II (RACE II) study; and the pharmacologic and nonpharmacologic options to control the ventricular rate during AF in the setting of HF. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. On rate-state and Coulomb failure models

    USGS Publications Warehouse

    Gomberg, J.; Beeler, N.; Blanpied, M.

    2000-01-01

    We examine the predictions of Coulomb failure stress and rate-state frictional models. We study the change in failure time (clock advance) Δt due to stress step perturbations (i.e., coseismic static stress increases) added to "background" stressing at a constant rate (i.e., tectonic loading) at time t0. The predictability of Δt implies a predictable change in seismicity rate r(t)/r0, testable using earthquake catalogs, where r0 is the constant rate resulting from tectonic stressing. Models of r(t)/r0, consistent with general properties of aftershock sequences, must predict an Omori law seismicity decay rate, a sequence duration that is less than a few percent of the mainshock cycle time and a return directly to the background rate. A Coulomb model requires that a fault remains locked during loading, that failure occur instantaneously, and that Δt is independent of t0. These characteristics imply an instantaneous infinite seismicity rate increase of zero duration. Numerical calculations of r(t)/r0 for different state evolution laws show that aftershocks occur on faults extremely close to failure at the mainshock origin time, that these faults must be "Coulomb-like," and that the slip evolution law can be precluded. Real aftershock population characteristics also may constrain rate-state constitutive parameters; a may be lower than laboratory values, the stiffness may be high, and/or normal stress may be lower than lithostatic. We also compare Coulomb and rate-state models theoretically. Rate-state model fault behavior becomes more Coulomb-like as constitutive parameter a decreases relative to parameter b. This is because the slip initially decelerates, representing an initial healing of fault contacts. The deceleration is more pronounced for smaller a, more closely simulating a locked fault. Even when the rate-state Δt has Coulomb characteristics, its magnitude may differ by some constant dependent on b. In this case, a rate-state model behaves like a modified

  13. 33 CFR 159.67 - Electrical component ratings.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Electrical component ratings. 159... (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must have current and voltage ratings equal to or greater than the...

  14. 33 CFR 159.67 - Electrical component ratings.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Electrical component ratings. 159... (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must have current and voltage ratings equal to or greater than the...

  15. 33 CFR 159.67 - Electrical component ratings.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Electrical component ratings. 159... (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must have current and voltage ratings equal to or greater than...

  16. 33 CFR 159.67 - Electrical component ratings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Electrical component ratings. 159... (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must have current and voltage ratings equal to or greater than...

  17. 33 CFR 159.67 - Electrical component ratings.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Electrical component ratings. 159... (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must have current and voltage ratings equal to or greater than...

  18. Using Generic Data to Establish Dormancy Failure Rates

    NASA Technical Reports Server (NTRS)

    Reistle, Bruce

    2014-01-01

    Many hardware items are dormant prior to being operated. The dormant period might be especially long, for example during missions to the moon or Mars. In missions with long dormant periods the risk incurred during dormancy can exceed the active risk contribution. Probabilistic Risk Assessments (PRAs) need to account for the dormant risk contribution as well as the active contribution. A typical method for calculating a dormant failure rate is to multiply the active failure rate by a constant, the dormancy factor. For example, some practitioners use a heuristic and divide the active failure rate by 30 to obtain an estimate of the dormant failure rate. To obtain a more empirical estimate of the dormancy factor, this paper uses the recently updated database NPRD-2011 [1] to arrive at a set of distributions for the dormancy factor. The resulting dormancy factor distributions are significantly different depending on whether the item is electrical, mechanical, or electro-mechanical. Additionally, this paper will show that using a heuristic constant fails to capture the uncertainty of the possible dormancy factors.

  19. High rate fabrication of compression molded components

    DOEpatents

    Matsen, Marc R.; Negley, Mark A.; Dykstra, William C.; Smith, Glen L.; Miller, Robert J.

    2016-04-19

    A method for fabricating a thermoplastic composite component comprises inductively heating a thermoplastic pre-form with a first induction coil by inducing current to flow in susceptor wires disposed throughout the pre-form, inductively heating smart susceptors in a molding tool to a leveling temperature with a second induction coil by applying a high-strength magnetic field having a magnetic flux that passes through surfaces of the smart susceptors, shaping the magnetic flux that passes through surfaces of the smart susceptors to flow substantially parallel to a molding surface of the smart susceptors, placing the heated pre-form between the heated smart susceptors; and applying molding pressure to the pre-form to form the composite component.

  20. Fatigue failure of metal components as a factor in civil aircraft accidents

    NASA Technical Reports Server (NTRS)

    Holshouser, W. L.; Mayner, R. D.

    1972-01-01

    A review of records maintained by the National Transportation Safety Board showed that 16,054 civil aviation accidents occurred in the United States during the 3-year period ending December 31, 1969. Material failure was an important factor in the cause of 942 of these accidents. Fatigue was identified as the mode of the material failures associated with the cause of 155 accidents and in many other accidents the records indicated that fatigue failures might have been involved. There were 27 fatal accidents and 157 fatalities in accidents in which fatigue failures of metal components were definitely identified. Fatigue failures associated with accidents occurred most frequently in landing-gear components, followed in order by powerplant, propeller, and structural components in fixed-wing aircraft and tail-rotor and main-rotor components in rotorcraft. In a study of 230 laboratory reports on failed components associated with the cause of accidents, fatigue was identified as the mode of failure in more than 60 percent of the failed components. The most frequently identified cause of fatigue, as well as most other types of material failures, was improper maintenance (including inadequate inspection). Fabrication defects, design deficiencies, defective material, and abnormal service damage also caused many fatigue failures. Four case histories of major accidents are included in the paper as illustrations of some of the factors invovled in fatigue failures of aircraft components.

  1. Reliability Evaluation of Machine Center Components Based on Cascading Failure Analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-Zhi; Liu, Jin-Tong; Shen, Gui-Xiang; Long, Zhe; Sun, Shu-Guang

    2017-07-01

    In order to rectify the problems that the component reliability model exhibits deviation, and the evaluation result is low due to the overlook of failure propagation in traditional reliability evaluation of machine center components, a new reliability evaluation method based on cascading failure analysis and the failure influenced degree assessment is proposed. A direct graph model of cascading failure among components is established according to cascading failure mechanism analysis and graph theory. The failure influenced degrees of the system components are assessed by the adjacency matrix and its transposition, combined with the Pagerank algorithm. Based on the comprehensive failure probability function and total probability formula, the inherent failure probability function is determined to realize the reliability evaluation of the system components. Finally, the method is applied to a machine center, it shows the following: 1) The reliability evaluation values of the proposed method are at least 2.5% higher than those of the traditional method; 2) The difference between the comprehensive and inherent reliability of the system component presents a positive correlation with the failure influenced degree of the system component, which provides a theoretical basis for reliability allocation of machine center system.

  2. What mechanisms are associated with tibial component failure after kinematically-aligned total knee arthroplasty?

    PubMed

    Nedopil, Alexander J; Howell, Stephen M; Hull, Maury L

    2017-08-01

    Eight patients treated with kinematically-aligned (KA) total knee arthroplasty (TKA) presented with tibial component failure. We determined whether radiographic measurements and clinical characteristics are different between patients with and without tibial component failure to identify mechanisms of failure and strategies to reduce the risk. Out of 3,212 primary TKAs (2,725 TKAs with a two-year minimum follow up), of which all were performed with KA, eight patients presented with tibial component failure. Radiographic measurements, clinical characteristics (e.g. age, gender, BMI, etc.), revision surgical records, and Oxford knee scores were compared to control cohort patients matched 1:3. Tibial component failure presented at an average of 28 ± 15 months after primary TKA. Patients with tibial component failure had a 6 kg/m(2) greater body mass index (p = 0.034) and 5° greater posterior slope of the tibia component (p = 0.002) than controls. Final follow-up averaged 56 ± 19 months after the primary TKA and 28 ± 24 months after the revision TKA. The final Oxford knee score was 39 ± 4.6 for patients with tibial component failure and 44 ± 6.5 for the controls (p = 0.005). The incidence of tibial component failure after KA TKA was 0.3% and was caused by posterior subsidence or posterior edge wear and not varus subsidence. The strategy for lowering the risk of tibial component failure when performing KA is to set the tibial component parallel to the flexion-extension plane (slope) and varus-valgus plane of the native joint line.

  3. Number and placement of control system components considering possible failures

    NASA Technical Reports Server (NTRS)

    Carignan, C. R.; Vandervelde, W. E.

    1982-01-01

    A decision making methodology is presented which is intended to be useful in the early stages of system design, before a control system is designed in detail. The methodology accounts for the likelihood of failure among the sensors and actuators in a control system. A method to compute the degree of controllability and degree of observability of a system for a given set of actuators and sensors is also presented.

  4. On the effects of component durations and component reinforcement rates in multiple schedules

    PubMed Central

    Charman, Lesle; Davison, Michael

    1982-01-01

    Four experiments, each using the same six pigeons, investigated the effects of varying component durations and component reinforcement rates in multiple variable-interval schedules. Experiment 1 used unequal component durations in which one component was five times the duration of the other, and the shorter component was varied over conditions from 120 seconds to 5 seconds. The schedules were varied over five values for each pair of component durations. Sensitivity to reinforcement rate changes was the same at all component durations. In Experiment 2, both component durations were 5 seconds, and the schedules were again varied using both one and two response keys. Sensitivity to reinforcement was not different from the values found in Experiment 1. In Experiment 3, various manipulations, including body-weight changes, reinforcer duration changes, blackouts, hopper lights correlated with keylights, and overall reinforcement rate changes were carried out. No reliable increase in reinforcement sensitivity resulted from any manipulation. Finally, in Experiment 4, reinforcement rates in the two components were kept constant and unequal, and the component durations were varied. Shorter components produced significantly increased response rates normally in the higher reinforcement rate component, but schedule reversals at short component durations eliminated the response rate increases. The effects of component duration on multiple schedule performance cannot be interpreted as changing sensitivity to reinforcement nor to changing bias. PMID:16812276

  5. Reliability bounds for fault-tolerant systems with competing responses to component failures

    NASA Technical Reports Server (NTRS)

    Lee, L. D.

    1985-01-01

    Bounds are established on the probability of system failure for fault-tolerant systems of the type used, for example, in aviation control. Event series leading to system failure are assumed to follow a semi-Markov model in which the potential sojourn times associated with component failures have exponential distributions and those associated with system responses have distributions with unspecified form. A product form of the bounds is derived by using a model that provides for multiple competing system responses to component failures.

  6. Reliability bounds for fault-tolerant systems with competing responses to component failures

    NASA Technical Reports Server (NTRS)

    Lee, L. D.

    1986-01-01

    Bounds are established on the probability of system failure for fault-tolerant systems of the type used, for example, in aviation control. Event series leading to system failure are assumed to follow a semi-Markov model in which the potential sojourn times associated with component failures have exponential distributions and those associated with system responses have distributions with unspecified form. A product form of the bounds is derived by using a model that provides for multiple competing system responses to component failures.

  7. Estimating distributions with increasing failure rate in an imperfect repair model.

    PubMed

    Kvam, Paul H; Singh, Harshinder; Whitaker, Lyn R

    2002-03-01

    A failed system is repaired minimally if after failure, it is restored to the working condition of an identical system of the same age. We extend the nonparametric maximum likelihood estimator (MLE) of a system's lifetime distribution function to test units that are known to have an increasing failure rate. Such items comprise a significant portion of working components in industry. The order-restricted MLE is shown to be consistent. Similar results hold for the Brown-Proschan imperfect repair model, which dictates that a failed component is repaired perfectly with some unknown probability, and is otherwise repaired minimally. The estimators derived are motivated and illustrated by failure data in the nuclear industry. Failure times for groups of emergency diesel generators and motor-driven pumps are analyzed using the order-restricted methods. The order-restricted estimators are consistent and show distinct differences from the ordinary MLEs. Simulation results suggest significant improvement in reliability estimation is available in many cases when component failure data exhibit the IFR property.

  8. Assessment of failure of cemented polyethylene acetabular component due to bone remodeling: A finite element study.

    PubMed

    Ghosh, Rajesh

    2016-09-01

    The aim of the study is to determine failure of the cemented polyethylene acetabular component, which might occur due to excessive bone resorption, cement-bone interface debonding and fatigue failure of the cement mantle. Three-dimensional finite element models of intact and implanted pelvic bone were developed and bone remodeling algorithm was implemented for present analysis. Soderberg fatigue failure diagram was used for fatigue assessment of the cement mantle. Hoffman failure criterion was considered for prediction of cement-bone interface debonding. Results indicate fatigue failure of the cement mantle and implant-bone interface debonding might not occur due to bone remodeling.

  9. Modified iterative aggregation procedure for maintenance optimisation of multi-component systems with failure interaction

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuoqi; Wu, Su; Lee, Seungchul; Ni, Jun

    2014-12-01

    This paper studies maintenance policies for multi-component systems which have failure interaction among their components. Component failure might accelerate deterioration processes or induce instantaneous failures of the remaining components. We formulate this maintenance problem as a Markov decision process (MDP) with an objective of minimising a total discounted maintenance cost. However, the action set and state space in MDP exponentially grow as the number of components increases. This makes traditional approaches computationally intractable. To deal with this curse of dimensionality, a modified iterative aggregation procedure (MIAP) is proposed. We mathematically prove that iterations in MIAP guarantee the convergence and the policy obtained is optimal. Numerical case studies find that failure interaction should not be ignored in a maintenance policy decision making and the proposed MIAP is faster and requires less computational memory size than that of linear programming.

  10. The Role of Manufacturing Defects in Munition Component Failures

    DTIC Science & Technology

    2001-04-05

    forging promotes desirable directional properties such as tensile strength and ductility, and dynamic 107 properties such as impact toughness, fracture ...shrinkage defects. Tensile testing showed that the specimens fabricated from the components did not meet the required mechanical properties for this alloy. In...components fail to meet the required mechanical properties , but the workmanship of the parts was less than acceptable. The extended analysis performed by

  11. Effect of Electromagnetic Navigated Ventriculoperitoneal Shunt Placement on Failure Rates

    PubMed Central

    Jung, Nayoung

    2013-01-01

    Objective To evaluate the effect of electromagnetic (EM) navigation system on ventriculoperitoneal (VP) shunt failure rate through comparing the result of standard shunt placement. Methods All patients undergoing VP shunt from October 2007 to September 2010 were included in this retrospective study. The first group received shunt surgery using EM navigation. The second group had catheters inserted using manual method with anatomical landmark. The relationship between proximal catheter position and shunt revision rate was evaluated using postoperative computed tomography by a 3-point scale. 1) Grade I; optimal position free-floating in cerebrospinal fluid, 2) Grade II; touching choroid or ventricular wall, 3) Grade III; tip within parenchyma. Results A total of 72 patients were participated, 27 with EM navigated shunts and 45 with standard shunts. Grade I was found in 25 patients from group 1 and 32 patients from group 2. Only 2 patients without use of navigation belonged to grade III. Proximal obstruction took place 7% in grade I, 15% in grade II and 100% in grade III. Shunt revision occurred in 11% of group 1 and 31% of group 2. Compared in terms of proximal catheter position, there was growing trend of revision rate according to increase of grade on each group. Although infection rate was similar between both groups, the result had no statistical meaning (p=0.905, chi-square test). Conclusion The use of EM navigation in routine shunt surgery can eliminate poor shunt placement resulting in a dramatic reduction in failure rates. PMID:23634264

  12. Use of All-polyethylene Tibial Components in Unicompartmental Knee Arthroplasty Increases the Risk of Early Failure.

    PubMed

    Koh, In Jun; Suhl, Kyung Hwan; Kim, Min Woo; Kim, Man Soo; Choi, Keun Young; In, Yong

    2017-01-13

    All-polyethylene (all-poly) tibial designs in primary total knee arthroplasty (TKA) have been reconsidered with excellent clinical outcomes, survivorship, and cost-effectiveness. However, whether all-poly tibial components provided comparable results to metal-backed modular components during unicompartmental knee arthroplasty (UKA) remains unclear. This study compared the clinical outcomes and prevalence of early failure between all-poly and metal-backed modular components in UKA. We retrospectively reviewed the records and radiographs of 101 consecutive UKAs. In total, 51 UKAs were performed using all-poly tibial components; 50 others used metal-backed modular components. Clinical and radiographic outcomes, adaptive bone remodeling assessed by radiographic bone density, and early failure prevalence rates were compared. Despite a lack of group differences in clinical and radiographic outcomes (p > 0.1 in all comparisons), adaptive bone remodeling at 2 years after surgery of all-poly UKAs was more progressive compared with metal-backed UKAs (1.2 in all-poly UKA group vs. 0.9 in metal-backed UKA group, p < 0.001). In addition, 6 of 51 all-poly UKAs failed within 2 years postoperatively, whereas no metal-backed UKAs failed (11% in all-poly UKA group vs. 0% in metal-backed UKA group, p = 0.027). All-poly tibial component use during UKA increased the risk of early failure, which may be due to a failure in tibial loading distribution.

  13. Optimal Aircraft Control Upset Recovery With and Without Component Failures

    NASA Technical Reports Server (NTRS)

    Sparks, Dean W.; Moerder, Daniel D.

    2002-01-01

    This paper treats the problem of recovering sustainable nondescending (safe) flight in a transport aircraft after one or more of its control effectors fail. Such recovery can be a challenging goal for many transport aircraft currently in the operational fleet for two reasons. First, they have very little redundancy in their means of generating control forces and moments. These aircraft have, as primary control surfaces, a single rudder and pairwise elevators and aileron/spoiler units that provide yaw, pitch, and roll moments with sufficient bandwidth to be used in stabilizing and maneuvering the airframe. Beyond this, throttling the engines can provide additional moments, but on a much slower time scale. Other aerodynamic surfaces, such as leading and trailing edge flaps, are only intended to be placed in a position and left, and are, hence, very slow-moving. Because of this, loss of a primary control surface strongly degrades the controllability of the vehicle, particularly when the failed effector becomes stuck in a non-neutral position where it exerts a disturbance moment that must be countered by the remaining operating effectors. The second challenge in recovering safe flight is that these vehicles are not agile, nor can they tolerate large accelerations. This is of special importance when, at the outset of the recovery maneuver, the aircraft is flying toward the ground, as is frequently the case when there are major control hardware failures. Recovery of safe flight is examined in this paper in the context of trajectory optimization. For a particular transport aircraft, and a failure scenario inspired by an historical air disaster, recovery scenarios are calculated with and without control surface failures, to bring the aircraft to safe flight from the adverse flight condition that it had assumed, apparently as a result of contact with a vortex from a larger aircraft's wake. An effort has been made to represent relevant airframe dynamics, acceleration limits

  14. Failure analysis of storage tank component in LNG regasification unit using fault tree analysis method (FTA)

    NASA Astrophysics Data System (ADS)

    Mulyana, Cukup; Muhammad, Fajar; Saad, Aswad H.; Mariah, Riveli, Nowo

    2017-03-01

    Storage tank component is the most critical component in LNG regasification terminal. It has the risk of failure and accident which impacts to human health and environment. Risk assessment is conducted to detect and reduce the risk of failure in storage tank. The aim of this research is determining and calculating the probability of failure in regasification unit of LNG. In this case, the failure is caused by Boiling Liquid Expanding Vapor Explosion (BLEVE) and jet fire in LNG storage tank component. The failure probability can be determined by using Fault Tree Analysis (FTA). Besides that, the impact of heat radiation which is generated is calculated. Fault tree for BLEVE and jet fire on storage tank component has been determined and obtained with the value of failure probability for BLEVE of 5.63 × 10-19 and for jet fire of 9.57 × 10-3. The value of failure probability for jet fire is high enough and need to be reduced by customizing PID scheme of regasification LNG unit in pipeline number 1312 and unit 1. The value of failure probability after customization has been obtained of 4.22 × 10-6.

  15. Component duration and relative response rates in multiple schedules.

    NASA Technical Reports Server (NTRS)

    Todorov, J. C.

    1972-01-01

    Pigeons were trained on a multiple variable-interval 30-sec, variable interval 90-sec schedule with each component presented alternately for an equal duration. This duration of exposure was varied from 5 to 300 sec. The rate of response in the variable-interval 30-sec component relative to the rate of response in the variable-interval 90-sec component was studied. Results are plotted and discussed.

  16. Application of Function-Failure Similarity Method to Rotorcraft Component Design

    NASA Technical Reports Server (NTRS)

    Roberts, Rory A.; Stone, Robert E.; Tumer, Irem Y.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Performance and safety are the top concerns of high-risk aerospace applications at NASA. Eliminating or reducing performance and safety problems can be achieved with a thorough understanding of potential failure modes in the designs that lead to these problems. The majority of techniques use prior knowledge and experience as well as Failure Modes and Effects as methods to determine potential failure modes of aircraft. During the design of aircraft, a general technique is needed to ensure that every potential failure mode is considered, while avoiding spending time on improbable failure modes. In this work, this is accomplished by mapping failure modes to specific components, which are described by their functionality. The failure modes are then linked to the basic functions that are carried within the components of the aircraft. Using this technique, designers can examine the basic functions, and select appropriate analyses to eliminate or design out the potential failure modes. The fundamentals of this method were previously introduced for a simple rotating machine test rig with basic functions that are common to a rotorcraft. In this paper, this technique is applied to the engine and power train of a rotorcraft, using failures and functions obtained from accident reports and engineering drawings.

  17. Scaling law of average failure rate and steady-state rate in rocks

    NASA Astrophysics Data System (ADS)

    Hao, Shengwang; Liu, Chao; Wang, Yingchong; Chang, Fuqing

    2017-06-01

    The evolution properties in the steady stage of a rock specimen are reflective of the damage or weakening growth within and thus are used to determine whether an unstable transition occurs. In this paper, we report the experimental results for rock (granite and marble) specimens tested at room temperature and room humidity under three typical loading modes: quasi-static monotonic loading, brittle creep, and brittle creep relaxation. Deformed rock specimens in current experiments exhibit an apparent steady stage characterized by a nearly constant evolution rate, which dominates the lifetime of the rock specimens. The average failure rate presents a common power-law relationship with the evolution rate in the steady stage, although the exponent is different for different loading modes. The results indicate that a lower ratio of the slope of the secondary stage with respect to the average rate of the entire lifetime implies a more brittle failure.

  18. Scaling law of average failure rate and steady-state rate in rocks

    NASA Astrophysics Data System (ADS)

    Hao, Shengwang; Liu, Chao; Wang, Yingchong; Chang, Fuqing

    2017-03-01

    The evolution properties in the steady stage of a rock specimen are reflective of the damage or weakening growth within and thus are used to determine whether an unstable transition occurs. In this paper, we report the experimental results for rock (granite and marble) specimens tested at room temperature and room humidity under three typical loading modes: quasi-static monotonic loading, brittle creep, and brittle creep relaxation. Deformed rock specimens in current experiments exhibit an apparent steady stage characterized by a nearly constant evolution rate, which dominates the lifetime of the rock specimens. The average failure rate presents a common power-law relationship with the evolution rate in the steady stage, although the exponent is different for different loading modes. The results indicate that a lower ratio of the slope of the secondary stage with respect to the average rate of the entire lifetime implies a more brittle failure.

  19. Component duration and relative response rates in multiple schedules1

    PubMed Central

    Todorov, João Claudio

    1972-01-01

    Pigeons were trained on a multiple variable-interval 30-sec, variable-interval 90-sec schedule with each component presented alternately for an equal (on the average) duration. This average duration of exposure to each component was varied from 5 to 300 sec. The main concern was with rate of response in the variable-interval 30-sec component relative to rate of response in the variable-interval 90-sec component. In all cases, rate of response was higher in the variable-interval 30 sec component, but the discrepancy in the rate produced by the two schedules tended to be greatest when the duration of component presentation was brief. The mean proportion of responses emitted during the variable-interval 30-sec component (responses in variable-interval 30-sec component divided by total responses) varied from about 0.60 to 0.71, where 0.75 would be expected on the basis of a matching rule, and 0.59 was that obtained by Lander and Irwin (1968). These results are in agreement with data reported by Shimp and Wheatley (1971) from a similar experiment. PMID:16811566

  20. Outpatient treatment of acute diverticulitis: rates and predictors of failure.

    PubMed

    Etzioni, David A; Chiu, Vicki Y; Cannom, Rebecca R; Burchette, Raoul J; Haigh, Philip I; Abbas, Maher A

    2010-06-01

    Many patients with acute diverticulitis can be managed as outpatients, but the success rate of this approach has not been thoroughly studied. We analyzed a large cohort of patients treated on an outpatient basis for an initial episode of acute diverticulitis to test our hypothesis that outpatient treatment of acute diverticulitis is highly effective. We analyzed patients within the Kaiser Permanente Southern California system (from 2006 to 2007) who were diagnosed with an initial episode of diverticulitis during an emergency room visit and subsequently discharged home. Each patient underwent a computed tomography (CT) scan for diagnosis or for confirmation of a diagnosis, and each radiologic report was evaluated regarding the presence of free fluid, phlegmon, perforation, and abscess. Treatment failure was defined as a return to the emergency room or an admission for diverticulitis within 60 days of the initial evaluation. Our study included 693 patients, of whom 54% were women, the average age was 58.5 years, and 6% failed treatment. In multivariate analysis, women (odds ratio, 3.08 [95% CI, 1.31-7.28]) and patients with free fluid on CT scan (odds ratio, 3.19 [95% CI, 1.45-7.05]) were at significantly higher risk for treatment failure. Age, white blood cell count, Charlson score, and duration of antibiotics were not significant predictive factors. In a retrospective analysis, among a cohort of patients who were referred for outpatient treatment, we found that such treatment was effective for the vast majority (94%) of patients. Women and those with free fluid on CT scan appear to be at higher risk for treatment failure.

  1. Voltage stress effects on microcircuit accelerated life test failure rates

    NASA Technical Reports Server (NTRS)

    Johnson, G. M.

    1976-01-01

    The applicability of Arrhenius and Eyring reaction rate models for describing microcircuit aging characteristics as a function of junction temperature and applied voltage was evaluated. The results of a matrix of accelerated life tests with a single metal oxide semiconductor microcircuit operated at six different combinations of temperature and voltage were used to evaluate the models. A total of 450 devices from two different lots were tested at ambient temperatures between 200 C and 250 C and applied voltages between 5 Vdc and 15 Vdc. A statistical analysis of the surface related failure data resulted in bimodal failure distributions comprising two lognormal distributions; a 'freak' distribution observed early in time, and a 'main' distribution observed later in time. The Arrhenius model was shown to provide a good description of device aging as a function of temperature at a fixed voltage. The Eyring model also appeared to provide a reasonable description of main distribution device aging as a function of temperature and voltage. Circuit diagrams are shown.

  2. In-vessel ITER tubing failure rates for selected materials and coolants

    SciTech Connect

    Marshall, T.D.; Cadwallader, L.C.

    1994-03-01

    Several materials have been suggested for fabrication of ITER in-vessel coolant tubing: beryllium, copper, Inconel, niobium, stainless steel, titanium, and vanadium. This report generates failure rates for the materials to identify the best performer from an operational safety and availability perspective. Coolant types considered in this report are helium gas, liquid lithium, liquid sodium, and water. Failure rates for the materials are generated by including the influence of ITER`s operating environment and anticipated tubing failure mechanisms with industrial operating experience failure rates. The analyses define tubing failure mechanisms for ITER as: intergranular attack, flow erosion, helium induced swelling, hydrogen damage, neutron irradiation embrittlement, cyclic fatigue, and thermal cycling. K-factors, multipliers, are developed to model each failure mechanism and are applied to industrial operating experience failure rates to generate tubing failure rates for ITER. The generated failure rates identify the best performer by its expected reliability. With an average leakage failure rate of 3.1e-10(m-hr){sup {minus}1}and an average rupture failure rate of 3.1e-11(m-hr){sup {minus}1}, titanium proved to be the best performer of the tubing materials. The failure rates generated in this report are intended to serve as comparison references for design safety and optimization studies. Actual material testing and analyses are required to validate the failure rates.

  3. Heart-rate variability depression in porcine peritonitis-induced sepsis without organ failure.

    PubMed

    Jarkovska, Dagmar; Valesova, Lenka; Chvojka, Jiri; Benes, Jan; Danihel, Vojtech; Sviglerova, Jitka; Nalos, Lukas; Matejovic, Martin; Stengl, Milan

    2017-05-01

    Depression of heart-rate variability (HRV) in conditions of systemic inflammation has been shown in both patients and experimental animal models and HRV has been suggested as an early indicator of sepsis. The sensitivity of HRV-derived parameters to the severity of sepsis, however, remains unclear. In this study we modified the clinically relevant porcine model of peritonitis-induced sepsis in order to avoid the development of organ failure and to test the sensitivity of HRV to such non-severe conditions. In 11 anesthetized, mechanically ventilated and instrumented domestic pigs of both sexes, sepsis was induced by fecal peritonitis. The dose of feces was adjusted and antibiotic therapy was administered to avoid multiorgan failure. Experimental subjects were screened for 40 h from the induction of sepsis. In all septic animals, sepsis with hyperdynamic circulation and increased plasma levels of inflammatory mediators developed within 12 h from the induction of peritonitis. The sepsis did not progress to multiorgan failure and there was no spontaneous death during the experiment despite a modest requirement for vasopressor therapy in most animals (9/11). A pronounced reduction of HRV and elevation of heart rate developed quickly (within 5 h, time constant of 1.97 ± 0.80 h for HRV parameter TINN) upon the induction of sepsis and were maintained throughout the experiment. The frequency domain analysis revealed a decrease in the high-frequency component. The reduction of HRV parameters and elevation of heart rate preceded sepsis-associated hemodynamic changes by several hours (time constant of 11.28 ± 2.07 h for systemic vascular resistance decline). A pronounced and fast reduction of HRV occurred in the setting of a moderate experimental porcine sepsis without organ failure. Inhibition of parasympathetic cardiac signaling probably represents the main mechanism of HRV reduction in sepsis. The sensitivity of HRV to systemic inflammation may allow

  4. Analysis of failure rate data with compound models

    SciTech Connect

    Shultis, J.K.; Eckhoff, N.D.; Johnson, D.E.; Milliken, G.A.; Drayer, D.D.; Gallup, D.R.; Buranapan, W.

    1982-06-01

    Information is presented concerning the distinction of failure data by the likelihood ratio test; detection of outliers in failure data; and properties of prior estimation techniques in Bayesian analyses.

  5. Development of KSC program for investigating and generating field failure rates. Reliability handbook for ground support equipment

    NASA Technical Reports Server (NTRS)

    Bloomquist, C. E.; Kallmeyer, R. H.

    1972-01-01

    Field failure rates and confidence factors are presented for 88 identifiable components of the ground support equipment at the John F. Kennedy Space Center. For most of these, supplementary information regarding failure mode and cause is tabulated. Complete reliability assessments are included for three systems, eight subsystems, and nine generic piece-part classifications. Procedures for updating or augmenting the reliability results are also included.

  6. Modeling Stress Strain Relationships and Predicting Failure Probabilities For Graphite Core Components

    SciTech Connect

    Duffy, Stephen

    2013-09-09

    This project will implement inelastic constitutive models that will yield the requisite stress-strain information necessary for graphite component design. Accurate knowledge of stress states (both elastic and inelastic) is required to assess how close a nuclear core component is to failure. Strain states are needed to assess deformations in order to ascertain serviceability issues relating to failure, e.g., whether too much shrinkage has taken place for the core to function properly. Failure probabilities, as opposed to safety factors, are required in order to capture the bariability in failure strength in tensile regimes. The current stress state is used to predict the probability of failure. Stochastic failure models will be developed that can accommodate possible material anisotropy. This work will also model material damage (i.e., degradation of mechanical properties) due to radiation exposure. The team will design tools for components fabricated from nuclear graphite. These tools must readily interact with finite element software--in particular, COMSOL, the software algorithm currently being utilized by the Idaho National Laboratory. For the eleastic response of graphite, the team will adopt anisotropic stress-strain relationships available in COMSO. Data from the literature will be utilized to characterize the appropriate elastic material constants.

  7. Analytical Method to Evaluate Failure Potential During High-Risk Component Development

    NASA Technical Reports Server (NTRS)

    Tumer, Irem Y.; Stone, Robert B.; Clancy, Daniel (Technical Monitor)

    2001-01-01

    Communicating failure mode information during design and manufacturing is a crucial task for failure prevention. Most processes use Failure Modes and Effects types of analyses, as well as prior knowledge and experience, to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. This paper makes use of similarities and tradeoffs that exist between different failure modes based on the functionality of each component/product. In this light, a function-failure method is developed to help the design of new products with solutions for functions that eliminate or reduce the potential of a failure mode. The method is applied to a simplified rotating machinery example in this paper, and is proposed as a means to account for helicopter failure modes during design and production, addressing stringent safety and performance requirements for NASA applications.

  8. Reproducibility of heart rate turbulence indexes in heart failure patients.

    PubMed

    D'Addio, Gianni; Cesarelli, Mario; Corbi, Graziamaria; Romano, Maria; Furgi, Giuseppe; Ferrara, Nicola; Rengo, Franco

    2010-01-01

    Cardiovascular oscillations following spontaneous ventricular premature complexes (VPC) are characterized by a short-term heart rate fluctuation known as heart rate turbulence (HRT) described by the so-called turbulence onset (TO) and slope (TS). Despite a recent written consensus on the standard of HRT measurement, reproducibility data are lacking. Aim of the paper was a reproducibility study of HRT indexes in heart failure patients (HF). Eleven HF patients underwent two 24h ECG Holter recordings, spaced 7 ± 5 days. A paired t test was used to assess the clinical stability of patients during the study period and the number of PVC in Holter recordings' couples. Both TO and TS indexes were calculated for each isolated VPC, and due to their skewed distribution, reproducibility of median and mean TO and TS was studied by Bland-Altman technique. Results showed that median HRT indexes might be preferred to commonly suggested mean values and that, although TO showed lower bias value than TS, TS can be considered much more reproducible than TO, comparing limits of agreements with normal values. This preliminary results suggest the use of medians instead of mean HRT indexes values and a reliability of the turbulence slope greater than the turbulence onset index.

  9. A probabilisitic based failure model for components fabricated from anisotropic graphite

    NASA Astrophysics Data System (ADS)

    Xiao, Chengfeng

    The nuclear moderator for high temperature nuclear reactors are fabricated from graphite. During reactor operations graphite components are subjected to complex stress states arising from structural loads, thermal gradients, neutron irradiation damage, and seismic events. Graphite is a quasi-brittle material. Two aspects of nuclear grade graphite, i.e., material anisotropy and different behavior in tension and compression, are explicitly accounted for in this effort. Fracture mechanic methods are useful for metal alloys, but they are problematic for anisotropic materials with a microstructure that makes it difficult to identify a "critical" flaw. In fact cracking in a graphite core component does not necessarily result in the loss of integrity of a nuclear graphite core assembly. A phenomenological failure criterion that does not rely on flaw detection has been derived that accounts for the material behaviors mentioned. The probability of failure of components fabricated from graphite is governed by the scatter in strength. The design protocols being proposed by international code agencies recognize that design and analysis of reactor core components must be based upon probabilistic principles. The reliability models proposed herein for isotropic graphite and graphite that can be characterized as being transversely isotropic are another set of design tools for the next generation very high temperature reactors (VHTR) as well as molten salt reactors. The work begins with a review of phenomenologically based deterministic failure criteria. A number of this genre of failure models are compared with recent multiaxial nuclear grade failure data. Aspects in each are shown to be lacking. The basic behavior of different failure strengths in tension and compression is exhibited by failure models derived for concrete, but attempts to extend these concrete models to anisotropy were unsuccessful. The phenomenological models are directly dependent on stress invariants. A set of

  10. Packaging-induced failure of semiconductor lasers and optical telecommunications components

    SciTech Connect

    Sharps, J.A.

    1996-12-31

    Telecommunications equipment for field deployment generally have specified lifetimes of > 100,000 hr. To achieve this high reliability, it is common practice to package sensitive components in hermetic, inert gas environments. The intent is to protect components from particulate and organic contamination, oxidation, and moisture. However, for high power density 980 nm diode lasers used in optical amplifiers, the authors found that hermetic, inert gas packaging induced a failure mode not observed in similar, unpackaged lasers. They refer to this failure mode as packaging-induced failure, or PIF. PIF is caused by nanomole amounts of organic contamination which interact with high intensity 980 nm light to form solid deposits over the emitting regions of the lasers. These deposits absorb 980 nm light, causing heating of the laser, narrowing of the band gap, and eventual thermal runaway. The authors have found PIF is averted by packaging with free O{sub 2} and/or a getter material that sequesters organics.

  11. Losartan improves heart rate variability and heart rate turbulence in heart failure due to ischemic cardiomyopathy.

    PubMed

    Ozdemir, Murat; Arslan, Uğur; Türkoğlu, Sedat; Balcioğlu, Serhat; Cengel, Atiye

    2007-12-01

    Heart rate variability (HRV) and heart rate turbulence are known to be disturbed and associated with excess mortality in heart failure. The aim of this study was to investigate whether losartan, when added on top of beta-blocker and angiotensin-converting enzyme inhibitor (ACEI) therapy, could improve these indices in patients with systolic heart failure. Seventy-seven patients (mean age 60.4 +/- 8.0, 80.5% male) with ischemic cardiomyopathy (mean ejection fraction 34.5 +/- 4.4%) and New York Heart Association Class II-III heart failure symptoms, already receiving a beta-blocker and an ACEI, were randomly assigned to either open-label losartan (losartan group) or no additional drug (control group) in a 2:1 ratio and the patients were followed for 12 weeks. The HRV and heart rate turbulence indices were calculated from 24-hour Holter recordings both at the beginning and at the end of follow-up. The baseline clinical characteristics, HRV, and heart rate turbulence indices were similar in the 2 groups. At 12 weeks of follow-up, all HRV parameters except pNN50 increased (SDNN: 113.2 +/- 34.2 versus 127.8 +/- 24.1, P = .001; SDANN: 101.5 +/- 31.7 versus 115.2 +/- 22.0, P = .001; triangular index: 29.9 +/- 11.1 versus 34.2 +/- 7.9, P = .008; RMSSD: 29.1 +/- 20.2 versus 34.3 +/- 23.0, P = .009; NN50: 5015.3 +/- 5554.9 versus 6446.7 +/- 6101.1, P = .024; NN50: 5.65 +/- 6.41 versus 7.24 +/- 6.99, P = .089; SDNNi: 45.1 +/- 13.3 versus 50.3 +/- 14.5, P = .004), turbulence onset decreased (-0. 61 +/- 1.70 versus -1.24 +/- 1.31, P = .003) and turbulence slope increased (4.107 +/- 3.881 versus 5.940 +/- 4.281, P = .004) significantly in the losartan group as compared with controls. A 12-week-long losartan therapy significantly improved HRV and heart rate turbulence in patients with Class II-III heart failure and ischemic cardiomyopathy already on beta-blockers and ACEI.

  12. U.S. Heart Failure Rates on the Rise

    MedlinePlus

    ... who are at increased risk for heart failure. Cardiovascular disease includes all types of heart disease, high blood ... than one-third of adults (92 million) have cardiovascular disease. In 2014, nearly 808,000 Americans died from ...

  13. (n, N) type maintenance policy for multi-component systems with failure interactions

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuoqi; Wu, Su; Li, Binfeng; Lee, Seungchul

    2015-04-01

    This paper studies maintenance policies for multi-component systems in which failure interactions and opportunistic maintenance (OM) involve. This maintenance problem can be formulated as a Markov decision process (MDP). However, since an action set and state space in MDP exponentially expand as the number of components increase, traditional approaches are computationally intractable. To deal with curse of dimensionality, we decompose such a multi-component system into mutually influential single-component systems. Each single-component system is formulated as an MDP with the objective of minimising its long-run average maintenance cost. Under some reasonable assumptions, we prove the existence of the optimal (n, N) type policy for a single-component system. An algorithm to obtain the optimal (n, N) type policy is also proposed. Based on the proposed algorithm, we develop an iterative approximation algorithm to obtain an acceptable maintenance policy for a multi-component system. Numerical examples find that failure interactions and OM pose significant effects on a maintenance policy.

  14. Smooth Nonparametric Estimation of the Failure Rate Function and its First Two Derivatives

    NASA Astrophysics Data System (ADS)

    Koshkin, G. M.

    2016-10-01

    The class of nonparametric estimators of kernel type is considered for the unknown failure rate function and its derivatives. The convergence of the suggested estimations in distribution and in the mean square sense to the unknown failure rate function and its derivatives is proved. The interval estimator of the failure rate function is constructed. Advantages of the nonparametric estimators in comparison with the parametric algorithms are discussed. The suggested estimators of the failure rate function can be used to solve problems of exploitation reliability of complex physical, technical, and software systems under uncertainty conditions.

  15. EEMD-based wind turbine bearing failure detection using the generator stator current homopolar component

    NASA Astrophysics Data System (ADS)

    Amirat, Yassine; Choqueuse, Vincent; Benbouzid, Mohamed

    2013-12-01

    Failure detection has always been a demanding task in the electrical machines community; it has become more challenging in wind energy conversion systems because sustainability and viability of wind farms are highly dependent on the reduction of the operational and maintenance costs. Indeed the most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the generator health degeneration, facilitating a proactive response, minimizing downtime, and maximizing productivity. This paper provides then an assessment of a failure detection techniques based on the homopolar component of the generator stator current and attempts to highlight the use of the ensemble empirical mode decomposition as a tool for failure detection in wind turbine generators for stationary and non-stationary cases.

  16. Microstructures, Forming Limit and Failure Analyses of Inconel 718 Sheets for Fabrication of Aerospace Components

    NASA Astrophysics Data System (ADS)

    Sajun Prasad, K.; Panda, Sushanta Kumar; Kar, Sujoy Kumar; Sen, Mainak; Murty, S. V. S. Naryana; Sharma, Sharad Chandra

    2017-04-01

    Recently, aerospace industries have shown increasing interest in forming limits of Inconel 718 sheet metals, which can be utilised in designing tools and selection of process parameters for successful fabrication of components. In the present work, stress-strain response with failure strains was evaluated by uniaxial tensile tests in different orientations, and two-stage work-hardening behavior was observed. In spite of highly preferred texture, tensile properties showed minor variations in different orientations due to the random distribution of nanoprecipitates. The forming limit strains were evaluated by deforming specimens in seven different strain paths using limiting dome height (LDH) test facility. Mostly, the specimens failed without prior indication of localized necking. Thus, fracture forming limit diagram (FFLD) was evaluated, and bending correction was imposed due to the use of sub-size hemispherical punch. The failure strains of FFLD were converted into major-minor stress space ( σ-FFLD) and effective plastic strain-stress triaxiality space ( ηEPS-FFLD) as failure criteria to avoid the strain path dependence. Moreover, FE model was developed, and the LDH, strain distribution and failure location were predicted successfully using above-mentioned failure criteria with two stages of work hardening. Fractographs were correlated with the fracture behavior and formability of sheet metal.

  17. Microstructures, Forming Limit and Failure Analyses of Inconel 718 Sheets for Fabrication of Aerospace Components

    NASA Astrophysics Data System (ADS)

    Sajun Prasad, K.; Panda, Sushanta Kumar; Kar, Sujoy Kumar; Sen, Mainak; Murty, S. V. S. Naryana; Sharma, Sharad Chandra

    2017-02-01

    Recently, aerospace industries have shown increasing interest in forming limits of Inconel 718 sheet metals, which can be utilised in designing tools and selection of process parameters for successful fabrication of components. In the present work, stress-strain response with failure strains was evaluated by uniaxial tensile tests in different orientations, and two-stage work-hardening behavior was observed. In spite of highly preferred texture, tensile properties showed minor variations in different orientations due to the random distribution of nanoprecipitates. The forming limit strains were evaluated by deforming specimens in seven different strain paths using limiting dome height (LDH) test facility. Mostly, the specimens failed without prior indication of localized necking. Thus, fracture forming limit diagram (FFLD) was evaluated, and bending correction was imposed due to the use of sub-size hemispherical punch. The failure strains of FFLD were converted into major-minor stress space (σ-FFLD) and effective plastic strain-stress triaxiality space (ηEPS-FFLD) as failure criteria to avoid the strain path dependence. Moreover, FE model was developed, and the LDH, strain distribution and failure location were predicted successfully using above-mentioned failure criteria with two stages of work hardening. Fractographs were correlated with the fracture behavior and formability of sheet metal.

  18. Oxygen analyzers: failure rates and life spans of galvanic cells.

    PubMed

    Meyer, R M

    1990-07-01

    Competing technologies exist for measuring oxygen concentrations in breathing circuits. Over a 4-year period, two types of oxygen analyzers were studied prospectively in routine clinical use to determine the incidence and nature of malfunctions. Newer AC-powered galvanic analyzers (North American Dräger O2med) were compared with older, battery-powered polarographic analyzers (Ohmeda 201) by recording all failures and necessary repairs. The AC-powered galvanic analyzer had a significantly lower incidence of failures (0.12 +/- 0.04 failures per machine-month) than the battery-powered polarographic analyzer (4.0 +/- 0.3 failures per machine-month). Disposable capsules containing the active galvanic cells lasted 12 +/- 7 months. Although the galvanic analyzers tended to remain out of service longer, awaiting the arrival of costly parts, the polarographic analyzers were more expensive to keep operating when calculations included the cost of time spent on repairs. Stocking galvanic capsules would have decreased the amount of time the galvanic analyzers were out of service, while increasing costs. In conclusion, galvanic oxygen analyzers appear capable of delivering more reliable service at a lower overall cost. By keeping the galvanic capsules exposed to room air during periods of storage, it should be possible to prolong their life span, further decreasing the cost of using them. In addition, recognizing the aberrations in their performance that warn of the exhaustion of the galvanic cells should permit timely recording and minimize downtime.

  19. A study of Mariner 10 flight experiences and some flight piece part failure rate computations

    NASA Technical Reports Server (NTRS)

    Paul, F. A.

    1976-01-01

    The problems and failures encountered in Mariner flight are discussed and the data available through a quantitative accounting of all electronic piece parts on the spacecraft are summarized. It also shows computed failure rates for electronic piece parts. It is intended that these computed data be used in the continued updating of the failure rate base used for trade-off studies and predictions for future JPL space missions.

  20. Derivation of Failure Rates and Probability of Failures for the International Space Station Probabilistic Risk Assessment Study

    NASA Technical Reports Server (NTRS)

    Vitali, Roberto; Lutomski, Michael G.

    2004-01-01

    National Aeronautics and Space Administration s (NASA) International Space Station (ISS) Program uses Probabilistic Risk Assessment (PRA) as part of its Continuous Risk Management Process. It is used as a decision and management support tool to not only quantify risk for specific conditions, but more importantly comparing different operational and management options to determine the lowest risk option and provide rationale for management decisions. This paper presents the derivation of the probability distributions used to quantify the failure rates and the probability of failures of the basic events employed in the PRA model of the ISS. The paper will show how a Bayesian approach was used with different sources of data including the actual ISS on orbit failures to enhance the confidence in results of the PRA. As time progresses and more meaningful data is gathered from on orbit failures, an increasingly accurate failure rate probability distribution for the basic events of the ISS PRA model can be obtained. The ISS PRA has been developed by mapping the ISS critical systems such as propulsion, thermal control, or power generation into event sequences diagrams and fault trees. The lowest level of indenture of the fault trees was the orbital replacement units (ORU). The ORU level was chosen consistently with the level of statistically meaningful data that could be obtained from the aerospace industry and from the experts in the field. For example, data was gathered for the solenoid valves present in the propulsion system of the ISS. However valves themselves are composed of parts and the individual failure of these parts was not accounted for in the PRA model. In other words the failure of a spring within a valve was considered a failure of the valve itself.

  1. A Mixed Methods Explanatory Study of the Failure/Drop Rate for Freshman STEM Calculus Students

    ERIC Educational Resources Information Center

    Worthley, Mary

    2013-01-01

    In a national context of high failure rates in freshman calculus courses, the purpose of this study was to understand who is struggling, and why. High failure rates are especially alarming given a local environment where students have access to a variety of academic, and personal, assistance. The sample consists of students at Colorado State…

  2. High Strain-Rate and Quasi-Static Ductile Failure Mechanisms in Porous Materials

    DTIC Science & Technology

    2007-11-02

    detailed understanding of the interrelated physical mechanisms that can result in ductile material failure in rate-dependent porous crystalline materials subjected...strains and slip-rates, and hydrostatic stresses on failure paths and ligament damage in face centered cubic (f.c.c.) crystalline materials have been

  3. A Mixed Methods Explanatory Study of the Failure/Drop Rate for Freshman STEM Calculus Students

    ERIC Educational Resources Information Center

    Worthley, Mary

    2013-01-01

    In a national context of high failure rates in freshman calculus courses, the purpose of this study was to understand who is struggling, and why. High failure rates are especially alarming given a local environment where students have access to a variety of academic, and personal, assistance. The sample consists of students at Colorado State…

  4. Clinical evaluation of the failure rates of metallic brackets

    PubMed Central

    ROMANO, Fábio Lourenço; CORRER, Américo Bortolazzo; CORRER-SOBRINHO, Lourenço; MAGNANI, Maria Beatriz Borges de Araújo; RUELLAS, Antônio Carlos de Oliveira

    2012-01-01

    Objectives The aim of this study was to evaluate in vivo the bonding of metallic orthodontic brackets with different adhesive systems. Material and Methods Twenty patients (10.5-15.1 years old) who had sought corrective orthodontic treatment at a University Orthodontic Clinic were evaluated. Brackets were bonded from the right second premolar to the left second premolar in the upper and lower arches using: Orthodontic Concise, conventional Transbond XT, Transbond XT without primer, and Transbond XT associated with Transbond Plus Self-etching Primer (TPSEP). The 4 adhesive systems were used in all patients using a split-mouth design; each adhesive system was used in one quadrant of each dental arch, so that each group of 5 patients received the same bonding sequence. Initial archwires were inserted 1 week after bracket bonding. The number of bracket failures for each adhesive system was quantified over a 6-month period. Results The number of debonded brackets was: 8- Orthodontic Concise, 2- conventional Transbond XT, 9- Transbond XT without primer, and 1- Transbond XT + TPSEP. By using the Kaplan-Meier methods, statistically significant differences were found between the materials (p=0.0198), and the Logrank test identified these differences. Conventional Transbond XT and Transbond XT + TPSEP adhesive systems were statistically superior to Orthodontic Concise and Transbond XT without primer (p<0.05). There was no statistically significant difference between the dental arches (upper and lower), between the dental arch sides (right and left), and among the quadrants. Conclusions The largest number of bracket failures occurred with Orthodontic Concise and Transbond XT without primer systems and few bracket failures occurred with conventional Transbond XT and Transbond XT+TPSEP. More bracket failures were observed in the posterior region compared with the anterior region. PMID:22666842

  5. Optical Methods For Automatic Rating Of Engine Test Components

    NASA Astrophysics Data System (ADS)

    Pritchard, James R.; Moss, Brian C.

    1989-03-01

    In recent years, increasing commercial and legislative pressure on automotive engine manufacturers, including increased oil drain intervals, cleaner exhaust emissions and high specific power outputs, have led to increasing demands on lubricating oil performance. Lubricant performance is defined by bench engine tests run under closely controlled conditions. After test, engines are dismantled and the parts rated for wear and accumulation of deposit. This rating must be consistently carried out in laboratories throughout the world in order to ensure lubricant quality meeting the specified standards. To this end, rating technicians evaluate components, following closely defined procedures. This process is time consuming, inaccurate and subject to drift, requiring regular recalibration of raters by means of international rating workshops. This paper describes two instruments for automatic rating of engine parts. The first uses a laser to determine the degree of polishing of the engine cylinder bore, caused by the reciprocating action of piston. This instrument has been developed to prototype stage by the NDT Centre at Harwell under contract to Exxon Chemical, and is planned for production within the next twelve months. The second instrument uses red and green filtered light to determine the type, quality and position of deposit formed on the piston surfaces. The latter device has undergone feasibility study, but no prototype exists.

  6. 12 CFR Appendix A to Subpart A of... - Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 9 2012-01-01 2012-01-01 false Minimum Capital Components for Interest Rate... Components for Interest Rate and Foreign Exchange Rate Contracts 1. The minimum capital components for interest rate and foreign exchange rate contracts are computed on the basis of the credit equivalent...

  7. Damage mechanisms and failure modes of cortical bone under components of physiological loading.

    PubMed

    George, W T; Vashishth, D

    2005-09-01

    Fatigue damage development in cortical bone was investigated in vitro under different mechanical components of physiological loading including tension, compression, and torsion. During each test, stress and strain data were collected continuously to monitor and statistically determine the occurrence of the primary, secondary, and tertiary stages associated with fatigue and/or creep failure of bone. The resultant microdamage and failure modes were identified by histological and fractographic analysis, respectively. The tensile group demonstrated Mode I cracking and the three classic stages of fatigue and creep suggesting a low crack initiation threshold, steady crack propagation and final failure by coalescence of microcracks. In contrast, the compressive group displayed Mode II cracking and a two-stage fatigue behavior with limited creep suggesting a high crack initiation threshold followed by a sudden fracture. The torsion group also displayed a two-stage fatigue profile but demonstrated extensive damage from mixed mode (Modes II and III) microcracking and predominant time-dependent damage. Thus, fatigue behavior of bone was found to be uniquely related to the individual mechanical components of physiological loading and the latter determined the specific damage mechanisms associated with fatigue fracture.

  8. Twisted Landau damping rates in multi-component dusty plasmas

    SciTech Connect

    Ali, S.; Bukhari, S.; Mendonca, J. T.

    2016-03-15

    Keeping in view the kinetic treatment for plasma particles, the electrostatic twisted dust-acoustic (DA) and dust-ion-acoustic (DIA) waves are investigated in a collisionless unmagnetized multi-component dusty plasma, whose constituents are the electrons, singly ionized positive ions, and negatively charged massive dust particulates. With this background, the Vlasov–Poisson equations are coupled together to derive a generalized dielectric constant by utilizing the Laguerre-Gaussian perturbed distribution function and electrostatic potential in the paraxial limit. The dispersion and damping rates of twisted DA and DIA waves are analyzed with finite orbital angular momentum states in a multi-component dusty plasma. Significant modifications concerning the real wave frequencies and damping rates appeared with varying twisted dimensionless parameter and dust concentration. In particular, it is shown that dust concentration enhances the phase speed of the DIA waves in contrary to DA waves, whereas the impact of twisted parameter reduces the frequencies of both DA and DIA waves. The results should be useful for the understanding of particle transport and trapping phenomena caused by wave excitation in laboratory dusty plasmas.

  9. The nova rate in the elliptical component of NGC 5128

    NASA Technical Reports Server (NTRS)

    Ciardullo, Robin; Tamblyn, Peter; Jacoby, George H.; Ford, Holland C.; Williams, R. E.

    1990-01-01

    The results are presented of a five year nova survey of NGC 5128 performed with an H-alpha filter at the prime focus of the CTIO 4 m telescope. In all, 16 novae were detected, of which 12 are members of a statistically complete and homogeneous sample unaffected by the absorption lane of the galaxy. When normalized to B luminosity, the nova rate in the elliptical component of NGC 5128 is 2.7 + or - 1.0 times less than that observed in the bulge of M31. However, when normalized in the infrared K bandpass, the two nova rates are identical, and comparable to that measured in the Large Magellanic Cloud. These data suggest that (1) the percentage of binary stars is approximately constant over a large range of star-forming environments, (2) the nova rate in our own galaxy is between 11 and 46/yr, and (3) nova rates are not strongly affected by tidal captures in bright globular clusters.

  10. Determining Oxidation Rates in Multi-component Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Sage, A. M.; Weitkamp, E. A.; Huff Hartz, K. E.; Robinson, A. L.; Donahue, N. M.

    2006-12-01

    Aerosol composition influences the kinetics of condensed-phase organic species, making extrapolation of rate constants from single-component systems to atmospherically-relevant mixtures difficult. Using a mixed-phase relative rate constants approach, we have overcome this difficulty, obtaining heterogeneous oxidation rate constants for each species in several multi-component organic mixtures. We have also derived a compound- specific uptake coefficient that relates these rate constants to previous uptake measurements. In the ozonolysis of model meat-cooking mixtures, we observe significant decay of saturated and unsaturated acids and sterols. By relating the observed decomposition of condensed-phase species to that of gas-phase standards, we track the evolution of effective rate constants for oleic acid and palmitoleic acid oxidation as the aerosol is chemically processed. Each decreases by nearly a factor of ten over the course of an experiment. Rate constants also depend strongly on aerosol composition, changing by more than an order of magnitude with increasing mixture complexity. To compare these results with previous results, we have derived a compound-specific uptake coefficient (γi' for condensed-phase species i), which describes the kinetics of reactive uptake in mixtures and can be meaningfully related to the traditional uptake coefficient. We express uptake in terms of the concentrations of condensed-phase species, and to do so accurately, we use alkanoic acids to correct the decay of reactive alkenoic acids for secondary chemistry. This correction is incorporated into the definition of γi', and in terms of γi', the standard uptake coefficient can be written as: γ=∑χiγi', where χi is the mass fraction of species i and the summation is over all oxidized species. By using condensed-phase decay to calculate the uptake, we have apportioned reactive uptake among responsible species. This provides information not only about the potential of a particle

  11. A stochastic node-failure network with individual tolerable error rate at multiple sinks

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Fu; Lin, Yi-Kuei

    2014-05-01

    Many enterprises consider several criteria during data transmission such as availability, delay, loss, and out-of-order packets from the service level agreements (SLAs) point of view. Hence internet service providers and customers are gradually focusing on tolerable error rate in transmission process. The internet service provider should provide the specific demand and keep a certain transmission error rate by their SLAs to each customer. This paper is mainly to evaluate the system reliability that the demand can be fulfilled under the tolerable error rate at all sinks by addressing a stochastic node-failure network (SNFN), in which each component (edge or node) has several capacities and a transmission error rate. An efficient algorithm is first proposed to generate all lower boundary points, the minimal capacity vectors satisfying demand and tolerable error rate for all sinks. Then the system reliability can be computed in terms of such points by applying recursive sum of disjoint products. A benchmark network and a practical network in the United States are demonstrated to illustrate the utility of the proposed algorithm. The computational complexity of the proposed algorithm is also analyzed.

  12. Vacuum Bellows, Vacuum Piping, Cryogenic Break, and Copper Joint Failure Rate Estimates for ITER Design Use

    SciTech Connect

    L. C. Cadwallader

    2010-06-01

    The ITER international project design teams are working to produce an engineering design in preparation for construction of the International Thermonuclear Experimental Reactor (ITER) tokamak. During the course of this work, questions have arisen in regard to safety barriers and equipment reliability as important facets of system design. The vacuum system designers have asked several questions about the reliability of vacuum bellows and vacuum piping. The vessel design team has asked about the reliability of electrical breaks and copper-copper joints used in cryogenic piping. Research into operating experiences of similar equipment has been performed to determine representative failure rates for these components. The following chapters give the research results and the findings for vacuum system bellows, power plant stainless steel piping (amended to represent vacuum system piping), cryogenic system electrical insulating breaks, and copper joints.

  13. In-Vessel Coil Material Failure Rate Estimates for ITER Design Use

    SciTech Connect

    L. C. Cadwallader

    2013-01-01

    The ITER international project design teams are working to produce an engineering design for construction of this large tokamak fusion experiment. One of the design issues is ensuring proper control of the fusion plasma. In-vessel magnet coils may be needed for plasma control, especially the control of edge localized modes (ELMs) and plasma vertical stabilization (VS). These coils will be lifetime components that reside inside the ITER vacuum vessel behind the blanket modules. As such, their reliability is an important design issue since access will be time consuming if any type of repair were necessary. The following chapters give the research results and estimates of failure rates for the coil conductor and jacket materials to be used for the in-vessel coils. Copper and CuCrZr conductors, and stainless steel and Inconel jackets are examined.

  14. Stress Analysis of B-52B and B-52H Air-Launching Systems Failure-Critical Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2005-01-01

    The operational life analysis of any airborne failure-critical structural component requires the stress-load equation, which relates the applied load to the maximum tangential tensile stress at the critical stress point. The failure-critical structural components identified are the B-52B Pegasus pylon adapter shackles, B-52B Pegasus pylon hooks, B-52H airplane pylon hooks, B-52H airplane front fittings, B-52H airplane rear pylon fitting, and the B-52H airplane pylon lower sway brace. Finite-element stress analysis was performed on the said structural components, and the critical stress point was located and the stress-load equation was established for each failure-critical structural component. The ultimate load, yield load, and proof load needed for operational life analysis were established for each failure-critical structural component.

  15. Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model

    SciTech Connect

    Fok, Alex

    2013-10-30

    The proposed work addresses the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the very high- temperature reactor (VHTR). Specifically, irradiation and environmental effects pertinent to the VHTR will be incorporated into the model to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the finite element method. The model uses a combined stress-based and fracture mechanics-based failure criterion, so it can simulate both the initiation and propagation of cracks. Modern imaging techniques, such as x-ray computed tomography and digital image correlation, will be used during material testing to help define the baseline material damage parameters. Monte Carlo analysis will be performed to address inherent variations in material properties, the aim being to reduce the arbitrariness and uncertainties associated with the current statistical approach. The results can potentially contribute to the current development of American Society of Mechanical Engineers (ASME) codes for the design and construction of VHTR core components.

  16. Number and placement of control system components considering possible failures. [for large space structures

    NASA Technical Reports Server (NTRS)

    Vander Velde, W. E.; Carignan, C. R.

    1984-01-01

    One of the first questions facing the designer of the control system for a large space structure is how many components actuators and sensors - to specify and where to place them on the structure. This paper presents a methodology which is intended to assist the designer in making these choices. A measure of controllability is defined which is a quantitative indication of how well the system can be controlled with a given set of actuators. Similarly, a measure of observability is defined which is a quantitative indication of how well the system can be observed with a given set of sensors. Then the effect of component unreliability is introduced by computing the average expected degree of controllability (observability) over the operating lifetime of the system accounting for the likelihood of various combinations of component failures. The problem of component location is resolved by optimizing this performance measure over the admissible set of locations. The variation of this optimized performance measure with number of actuators (sensors) is helpful in deciding how many components to use.

  17. Heart Rate As a Biomarker in Heart Failure: Role of Heart Rate Lowering Agents.

    PubMed

    Shaaya, Ghazwan; Al-Khazaali, Ali; Arora, Rohit

    Heart failure (HF) is a common clinical condition affecting more than 5.8 million people in the United States, it remains the leading cause of death in the United States and worldwide. Ongoing challenges for biomarker identification include the need for objective assessment, measurement precision, and meaningful replication. Biomarkers not only serve as traditional predictors of prognosis, they can also help to identify high-risk patients who need closer monitoring and more aggressive therapy; therefore, we reviewed the use of heart rate (HR) as a biomarker in HF both of diagnostic and prognostic values, in addition, to being easily detected. HR is a determinant of myocardial oxygen demand, coronary blood flow, and myocardial performance and is central to the adaptation of cardiac output to metabolic needs. Increased HR is known to predict adverse outcome in the general population and in patients with chronic HF. Part of the ability of HR to predict risk is related to the forces driving it, namely, neurohormonal activation. We reviewed therapies, which slow the HR like β-blockers and ivabradine (a drug that is a pure HR-reducing agent), and all the clinical studies suggest the benefit of these drugs in the management of HF, and increasing evidence suggests HR as a biomarker of both diagnostic and prognostic values in HF.

  18. The impact of vaccine failure rate on epidemic dynamics in responsive networks

    NASA Astrophysics Data System (ADS)

    Liang, Yu-Hao; Juang, Jonq

    2015-04-01

    An SIS model based on the microscopic Markov-chain approximation is considered in this paper. It is assumed that the individual vaccination behavior depends on the contact awareness, local and global information of an epidemic. To better simulate the real situation, the vaccine failure rate is also taken into consideration. Our main conclusions are given in the following. First, we show that if the vaccine failure rate α is zero, then the epidemic eventually dies out regardless of what the network structure is or how large the effective spreading rate and the immunization response rates of an epidemic are. Second, we show that for any positive α, there exists a positive epidemic threshold depending on an adjusted network structure, which is only determined by the structure of the original network, the positive vaccine failure rate and the immunization response rate for contact awareness. Moreover, the epidemic threshold increases with respect to the strength of the immunization response rate for contact awareness. Finally, if the vaccine failure rate and the immunization response rate for contact awareness are positive, then there exists a critical vaccine failure rate αc > 0 so that the disease free equilibrium (DFE) is stable (resp., unstable) if α < αc (resp., α > αc). Numerical simulations to see the effectiveness of our theoretical results are also provided.

  19. Optimized Treatment and Heart Rate Reduction in Chronic Heart Failure

    PubMed Central

    Moreno, Irineu Blanco; Del Carlo, Carlos Henrique; Pereira-Barretto, Antônio Carlos

    2013-01-01

    Background Heart failure (HF) is a syndrome that leads to poor outcome in advanced forms. The neurohormonal blockade modifies this natural history; however, it is often suboptimal. Objective The aim of this study is to assess at what percentage cardiologists used to treating HF can prescribe target doses of drugs of proven efficacy. Methods A total of 104 outpatients with systolic dysfunction were consecutively enrolled, all under stabilized treatment. Demographic and treatment data were evaluated and the doses achieved were verified. The findings are shown as percentages and correlations are made between different variables. Results The mean age of patients was 64.1 ± 14.2 years, with SBP =115.4 ± 15.3, HR = 67.8 ± 9.4 bpm, weight = 76.0 ± 17.0 kg and sinus rhythm (90.4%). As for treatment, 93.3% received a RAS blocker (ACEI 52.9%), all received beta-blockers (BB), the most often prescribed being carvedilol (92.3%). As for the doses: 97.1% of those receiving an ARB were below the optimal dose and of those who received ACEI, 52.7% received an optimized dose. As for the BB, target doses were prescribed to 76.0% of them. In this group of patients, most with BB target dose, it can be seen that 36.5% had HR ≥ 70 bpm in sinus rhythm. Conclusion Cardiologists used to treating HF can prescribe target doses of ACEI and BB to most patients. Even though they receive the recommended doses, about one third of patients persists with HR > 70 bpm and should have their treatment optimized. PMID:24100693

  20. Risk assessment of component failure modes and human errors using a new FMECA approach: application in the safety analysis of HDR brachytherapy.

    PubMed

    Giardina, M; Castiglia, F; Tomarchio, E

    2014-12-01

    Failure mode, effects and criticality analysis (FMECA) is a safety technique extensively used in many different industrial fields to identify and prevent potential failures. In the application of traditional FMECA, the risk priority number (RPN) is determined to rank the failure modes; however, the method has been criticised for having several weaknesses. Moreover, it is unable to adequately deal with human errors or negligence. In this paper, a new versatile fuzzy rule-based assessment model is proposed to evaluate the RPN index to rank both component failure and human error. The proposed methodology is applied to potential radiological over-exposure of patients during high-dose-rate brachytherapy treatments. The critical analysis of the results can provide recommendations and suggestions regarding safety provisions for the equipment and procedures required to reduce the occurrence of accidental events.

  1. Influence of enamel preservation on failure rates of porcelain laminate veneers.

    PubMed

    Gurel, Galip; Sesma, Newton; Calamita, Marcelo A; Coachman, Christian; Morimoto, Susana

    2013-01-01

    The purpose of this study was to evaluate the failure rates of porcelain laminate veneers (PLVs) and the influence of clinical parameters on these rates in a retrospective survey of up to 12 years. Five hundred eighty laminate veneers were bonded in 66 patients. The following parameters were analyzed: type of preparation (depth and margin), crown lengthening, presence of restoration, diastema, crowding, discoloration, abrasion, and attrition. Survival was analyzed using the Kaplan-Meier method. Cox regression modeling was used to determine which factors would predict PLV failure. Forty-two veneers (7.2%) failed in 23 patients, and an overall cumulative survival rate of 86% was observed. A statistically significant association was noted between failure and the limits of the prepared tooth surface (margin and depth). The most frequent failure type was fracture (n = 20). The results revealed no significant influence of crown lengthening apically, presence of restoration, diastema, discoloration, abrasion, or attrition on failure rates. Multivariable analysis (Cox regression model) also showed that PLVs bonded to dentin and teeth with preparation margins in dentin were approximately 10 times more likely to fail than PLVs bonded to enamel. Moreover, coronal crown lengthening increased the risk of PLV failure by 2.3 times. A survival rate of 99% was observed for veneers with preparations confined to enamel and 94% for veneers with enamel only at the margins. Laminate veneers have high survival rates when bonded to enamel and provide a safe and predictable treatment option that preserves tooth structure.

  2. Reducing the failure rate in introductory physics classes

    NASA Astrophysics Data System (ADS)

    Saul, Jeff; Coulombe, Patrick; Lindell, Rebecca

    2017-01-01

    Calculus-based introductory physics courses are often among the most difficult at many colleges and universities. With the national movement to increase STEM majors, the introductory calculus-based courses need to be less of a weed-out course and more of a course that propels students forward into successful majors. This talk discusses two approaches to reduce DFW rates and improve student retention: studio courses and parachute courses. Studio courses integrate lecture/laboratory into one course where the primary mode of instruction is small group activities. Typically, any students enrolled in the college or university can enroll in a studio version of the course. Parachute courses on the other hand, focus on the poor performing students. Designed so that students not doing well in an introductory physics course can switch into the parachute class mid-semester without harm to their GPA. In addition, the parachute course focuses on helping students build the knowledge and skills necessary for success when retaking the calculus-based Physics course. The studio course format has been found to reduce DFW rates at several universities by 40-60% compared with separate lecture and laboratory format versions of the same courses, while parachutes courses were less successful. At one university, the parachute course succeeded in helping 80% of students maintain their GPA, but only helped 20% successfully pass the calculus-based physics course.

  3. Extremely high fracture rate of a modular acetabular component with a sandwich polyethylene ceramic insertion for THA: a preliminary report.

    PubMed

    Kircher, Jörn; Bader, Rainer; Schroeder, Bettina; Mittelmeier, Wolfram

    2009-09-01

    Improvements of ceramic components and design changes have reduced failure rates over the past 30 years in total hip arthroplasty. We present a series of n = 11 cases with ceramic failure out of n = 113 implantations, from which n = 66 were ceramic-on-ceramic (n = 50 with ceramic insert with sandwich in polyethylene and n = 16 with directly fixed ceramic inlay) and n = 47 ceramic on polyethylene bearings, between 1999 and 2001 after introduction of a new implantation system to the market. The overall fracture rate of ceramic for the whole series (n = 113) was 9.7%. For the combination ceramic head with UHMW-PE (n = 47) the fracture rate was 2.1%. For the combination ceramic with ceramic (n = 66) the fracture rate was 15.2%. For the combination ceramic with ceramic sandwich in PE (n = 50) the failure rate was 18%. Only three patients experienced a trauma. Demography of patients (age, gender, body weight and BMI) was not statistically different between patients with failed ceramics and the rest of the patients making patient-specific risk factors unlikely to be an explanation for the failures. Retrospective X-ray analysis of the cup positioning did not show significant difference between failed and non-failed implants in terms of mean cup inclination and version making also operation-specific factors unlikely to be the only reason of this high failure rate. Therefore, manufacturer-specific factors such as design features may have contributed to this high failure rate. Further analysis of the whole series with biomechanical testing of the retrieved material needs to be performed.

  4. Pitfalls and Precautions When Using Predicted Failure Data for Quantitative Analysis of Safety Risk for Human Rated Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Hatfield, Glen S.; Hark, Frank; Stott, James

    2016-01-01

    Launch vehicle reliability analysis is largely dependent upon using predicted failure rates from data sources such as MIL-HDBK-217F. Reliability prediction methodologies based on component data do not take into account risks attributable to manufacturing, assembly, and process controls. These sources often dominate component level reliability or risk of failure probability. While consequences of failure is often understood in assessing risk, using predicted values in a risk model to estimate the probability of occurrence will likely underestimate the risk. Managers and decision makers often use the probability of occurrence in determining whether to accept the risk or require a design modification. Due to the absence of system level test and operational data inherent in aerospace applications, the actual risk threshold for acceptance may not be appropriately characterized for decision making purposes. This paper will establish a method and approach to identify the pitfalls and precautions of accepting risk based solely upon predicted failure data. This approach will provide a set of guidelines that may be useful to arrive at a more realistic quantification of risk prior to acceptance by a program.

  5. Failure rate of inferior alveolar nerve block among dental students and interns

    PubMed Central

    AlHindi, Maryam; Rashed, Bayan; AlOtaibi, Noura

    2016-01-01

    Objectives: To report the failure rate of inferior alveolar nerve block (IANB) among dental students and interns, causes of failure, investigate awareness of different IANB techniques, and to report IANB-associated complications. Methods: A 3-page questionnaire containing 13 questions was distributed to a random sample of 350 third to fifth years students and interns at the College of Dentistry, King Saud University, Riyadh, Saudi Arabia on January 2011. It included demographic questions (age, gender, and academic level) and questions on IANB failure frequency and reasons, actions taken to overcome the failure, and awareness of different anesthetic techniques, supplementary techniques, and complications. Results: Of the 250 distributed questionnaires, 238 were returned (68% response rate). Most (85.7%) of surveyed sample had experienced IANB failure once or twice. The participants attributed the failures most commonly (66.45%) to anatomical variations. The most common alternative technique used was intraligamentary injection (57.1%), although 42.8% of the sample never attempted any alternatives. Large portion of the samples stated that they either lacked both knowledge of and training for other techniques (44.9%), or that they had knowledge of them but not enough training to perform them (45.8%). Conclusion: To decrease IANB failure rates for dental students and interns, knowledge of landmarks, anatomical variation and their training in alternatives to IANB, such as the Gow-Gates and Akinosi techniques, both theoretically and clinically in the dental curriculum should be enhanced. PMID:26739980

  6. A Study to Compare the Failure Rates of Current Space Shuttle Ground Support Equipment with the New Pathfinder Equipment and Investigate the Effect that the Proposed GSE Infrastructure Upgrade Might Have to Reduce GSE Infrastructure Failures

    NASA Technical Reports Server (NTRS)

    Kennedy, Barbara J.

    2004-01-01

    The purposes of this study are to compare the current Space Shuttle Ground Support Equipment (GSE) infrastructure with the proposed GSE infrastructure upgrade modification. The methodology will include analyzing the first prototype installation equipment at Launch PAD B called the "Pathfinder". This study will begin by comparing the failure rate of the current components associated with the "Hardware interface module (HIM)" at the Kennedy Space Center to the failure rate of the neW Pathfinder components. Quantitative data will be gathered specifically on HIM components and the PAD B Hypergolic Fuel facility and Hypergolic Oxidizer facility areas which has the upgraded pathfinder equipment installed. The proposed upgrades include utilizing industrial controlled modules, software, and a fiber optic network. The results of this study provide evidence that there is a significant difference in the failure rates of the two studied infrastructure equipment components. There is also evidence that the support staff for each infrastructure system is not equal. A recommendation to continue with future upgrades is based on a significant reduction of failures in the new' installed ground system components.

  7. Failure analysis of an aluminum alloy material framework component induced by casting defects

    NASA Astrophysics Data System (ADS)

    Li, Bo; Hu, Weiye

    2017-09-01

    Failure analysis on a fractured radome framework component was carried out through visual observations, metallographic examination using optical microscope, fractog-raphy inspections using scanning electron microscope and chemical composition analysis. The failed frame was made of casting Al–Si7–Mg0.4 aluminum alloy. It had suffered a former vi-bration performance tests. It was indicated that the fractures were attributed to fatigue cracks which were induced by casting porosities at the outer surfaces of frame. Failure analysis was carefully conducted for the semi-penetrating crack appearing on the framework. According to the fractography inspected by scanning electron microscope, it was indicated that numerous casting porosities at the outer surface of the framework played the role of multiple fracture sources due to some applied stresses. Optical microstructure observations suggested that the dendrite-shaped casting porosities largely contributed to the crack-initiation. The groove-shaped structure at roots of spatial convex-bodies on the edge of casting porosities supplied the preferred paths of the crack-propagation. Besides, the brittle silicon eutectic particles distrib-uting along grain boundaries induced the intergranular fracture mode in the region of the over-load final fracture surface.

  8. Development of KSC program for investigating and generating field failure rates. Volume 2: Recommended format for reliability handbook for ground support equipment

    NASA Technical Reports Server (NTRS)

    Bloomquist, C. E.; Kallmeyer, R. H.

    1972-01-01

    Field failure rates and confidence factors are presented for 88 identifiable components of the ground support equipment at the John F. Kennedy Space Center. For most of these, supplementary information regarding failure mode and cause is tabulated. Complete reliability assessments are included for three systems, eight subsystems, and nine generic piece-part classifications. Procedures for updating or augmenting the reliability results presented in this handbook are also included.

  9. Fatigue failure of reverse shoulder humeral tray components of a single design.

    PubMed

    Lewicki, Kathleen A; Martin, Audrey J; Bell, John-Erik; Van Citters, Douglas W

    2016-08-01

    Modularity in shoulder arthroplasty provides surgical flexibility and facilitates less-complex revision surgery. Modular designs must fit in the glenohumeral joint space, necessitating minimal thickness and careful material selection. The potential for fatigue fracture is higher, and fatigue fracture has been experienced by patients. The purpose of this study was to determine the impact of geometry and materials used for modular humeral trays from a single manufacturer. We consecutively retrieved 8 humeral trays of nearly identical designs: 4 Ti-6Al-4V (Ti) and 4 CoCrMo (CoCr). Optical microscopy and scanning electron microscopy were used, along with metallurgical techniques. Finite element and fatigue analyses of the stresses at the humeral tray taper informed observation interpretation. Two Ti devices were revised for in vivo fracture. Scanning electron microscopy showed cracking in the other 2 Ti trays and no evidence of cracking in the CoCr components. A geometric difference in the CoCr devices resulted in a 25% decreased stress under simulated activities of daily living. Accounting for the tray material properties, the fatigue failure envelope ranged from 1000 to 1 million cycles for Ti and from 30,000 to >10 million cycles for CoCr. All Ti humeral tray retrievals fractured in vivo or were cracked at the taper fillet. No CoCr retrievals showed signs of cracking. Finite element and fatigue analyses predict a 10-fold lifetime increase for the CoCr devices compared with the Ti devices. This study shows that fatigue failure is possible for some reverse shoulder components and is likely exacerbated by fillet radius, tray thickness, and material choice. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  10. "Failure Is a Major Component of Learning Anything": The Role of Failure in the Development of STEM Professionals

    NASA Astrophysics Data System (ADS)

    Simpson, Amber; Maltese, Adam

    2017-04-01

    The term failure typically evokes negative connotations in educational settings and is likely to be accompanied by negative emotional states, low sense of confidence, and lack of persistence. These negative emotional and behavioral states may factor into an individual not pursuing a degree or career in science, technology, engineering, or mathematics (STEM). This is of particular concern considering the low number of women and underrepresented minorities pursing and working in a STEM field. Utilizing interview data with professionals across STEM, we sought to understand the role failure played in the persistence of individuals who enter and pursue paths toward STEM-related careers. Findings highlighted how participants' experiences with failure (1) shaped their outlooks or views of failure, (2) shaped their trajectories within STEM, and (3) provided them with additional skills or qualities. A few differences based on participants' sex, field, and highest degree also manifested in our analysis. We expect the results from this study to add research-based results to the current conversation around whether experiences with failure should be part of formal and informal educational settings and standards-based practices.

  11. "Failure Is a Major Component of Learning Anything": The Role of Failure in the Development of STEM Professionals

    NASA Astrophysics Data System (ADS)

    Simpson, Amber; Maltese, Adam

    2016-12-01

    The term failure typically evokes negative connotations in educational settings and is likely to be accompanied by negative emotional states, low sense of confidence, and lack of persistence. These negative emotional and behavioral states may factor into an individual not pursuing a degree or career in science, technology, engineering, or mathematics (STEM). This is of particular concern considering the low number of women and underrepresented minorities pursing and working in a STEM field. Utilizing interview data with professionals across STEM, we sought to understand the role failure played in the persistence of individuals who enter and pursue paths toward STEM-related careers. Findings highlighted how participants' experiences with failure (1) shaped their outlooks or views of failure, (2) shaped their trajectories within STEM, and (3) provided them with additional skills or qualities. A few differences based on participants' sex, field, and highest degree also manifested in our analysis. We expect the results from this study to add research-based results to the current conversation around whether experiences with failure should be part of formal and informal educational settings and standards-based practices.

  12. Crop failure rates in a geoengineered climate: impact of climate change and marine cloud brightening

    NASA Astrophysics Data System (ADS)

    Parkes, B.; Challinor, A.; Nicklin, K.

    2015-08-01

    The impact of geoengineering on crops has to date been studied by examining mean yields. We present the first work focusing on the rate of crop failures under a geoengineered climate. We investigate the impact of a future climate and a potential geoengineering scheme on the number of crop failures in two regions, Northeastern China and West Africa. Climate change associated with a doubling of atmospheric carbon dioxide increases the number of crop failures in Northeastern China while reducing the number of crop failures in West Africa. In both regions marine cloud brightening is likely to reduce the number crop failures, although it is more effective at reducing mild crop failure than severe crop failure. We find that water stress, rather than heat stress, is the main cause of crop failure in current, future and geoengineered climates. This demonstrates the importance of irrigation and breeding for tolerance to water stress as adaptation methods in all futures. Analysis of global rainfall under marine cloud brightening has the potential to significantly reduce the impact of climate change on global wheat and groundnut production.

  13. An Efficient Implementation of Fixed Failure-Rate Ratio Test for GNSS Ambiguity Resolution.

    PubMed

    Hou, Yanqing; Verhagen, Sandra; Wu, Jie

    2016-06-23

    Ambiguity Resolution (AR) plays a vital role in precise GNSS positioning. Correctly-fixed integer ambiguities can significantly improve the positioning solution, while incorrectly-fixed integer ambiguities can bring large positioning errors and, therefore, should be avoided. The ratio test is an extensively used test to validate the fixed integer ambiguities. To choose proper critical values of the ratio test, the Fixed Failure-rate Ratio Test (FFRT) has been proposed, which generates critical values according to user-defined tolerable failure rates. This contribution provides easy-to-implement fitting functions to calculate the critical values. With a massive Monte Carlo simulation, the functions for many different tolerable failure rates are provided, which enriches the choices of critical values for users. Moreover, the fitting functions for the fix rate are also provided, which for the first time allows users to evaluate the conditional success rate, i.e., the success rate once the integer candidates are accepted by FFRT. The superiority of FFRT over the traditional ratio test regarding controlling the failure rate and preventing unnecessary false alarms is shown by a simulation and a real data experiment. In the real data experiment with a baseline of 182.7 km, FFRT achieved much higher fix rates (up to 30% higher) and the same level of positioning accuracy from fixed solutions as compared to the traditional critical value.

  14. An Efficient Implementation of Fixed Failure-Rate Ratio Test for GNSS Ambiguity Resolution

    PubMed Central

    Hou, Yanqing; Verhagen, Sandra; Wu, Jie

    2016-01-01

    Ambiguity Resolution (AR) plays a vital role in precise GNSS positioning. Correctly-fixed integer ambiguities can significantly improve the positioning solution, while incorrectly-fixed integer ambiguities can bring large positioning errors and, therefore, should be avoided. The ratio test is an extensively used test to validate the fixed integer ambiguities. To choose proper critical values of the ratio test, the Fixed Failure-rate Ratio Test (FFRT) has been proposed, which generates critical values according to user-defined tolerable failure rates. This contribution provides easy-to-implement fitting functions to calculate the critical values. With a massive Monte Carlo simulation, the functions for many different tolerable failure rates are provided, which enriches the choices of critical values for users. Moreover, the fitting functions for the fix rate are also provided, which for the first time allows users to evaluate the conditional success rate, i.e., the success rate once the integer candidates are accepted by FFRT. The superiority of FFRT over the traditional ratio test regarding controlling the failure rate and preventing unnecessary false alarms is shown by a simulation and a real data experiment. In the real data experiment with a baseline of 182.7 km, FFRT achieved much higher fix rates (up to 30% higher) and the same level of positioning accuracy from fixed solutions as compared to the traditional critical value. PMID:27347949

  15. "Failure Is a Major Component of Learning Anything": The Role of Failure in the Development of STEM Professionals

    ERIC Educational Resources Information Center

    Simpson, Amber; Maltese, Adam

    2017-01-01

    The term failure typically evokes negative connotations in educational settings and is likely to be accompanied by negative emotional states, low sense of confidence, and lack of persistence. These negative emotional and behavioral states may factor into an individual not pursuing a degree or career in science, technology, engineering, or…

  16. Metallic wear debris sensors: promising developments in failure prevention for wind turbine gearsets and similar components

    NASA Astrophysics Data System (ADS)

    Poley, Jack; Dines, Michael

    2011-04-01

    Wind turbines are frequently located in remote, hard-to-reach locations, making it difficult to apply traditional oil analysis sampling of the machine's critical gearset at timely intervals. Metal detection sensors are excellent candidates for sensors designed to monitor machine condition in vivo. Remotely sited components, such as wind turbines, therefore, can be comfortably monitored from a distance. Online sensor technology has come of age with products now capable of identifying onset of wear in time to avoid or mitigate failure. Online oil analysis is now viable, and can be integrated with onsite testing to vet sensor alarms, as well as traditional oil analysis, as furnished by offsite laboratories. Controlled laboratory research data were gathered from tests conducted on a typical wind turbine gearbox, wherein total ferrous particle measurement and metallic particle counting were employed and monitored. The results were then compared with a physical inspection for wear experienced by the gearset. The efficacy of results discussed herein strongly suggests the viability of metallic wear debris sensors in today's wind turbine gearsets, as correlation between sensor data and machine trauma were very good. By extension, similar components and settings would also seem amenable to wear particle sensor monitoring. To our knowledge no experiments such as described herein, have previously been conducted and published.

  17. Rhythm control versus rate control for atrial fibrillation and heart failure.

    PubMed

    Roy, Denis; Talajic, Mario; Nattel, Stanley; Wyse, D George; Dorian, Paul; Lee, Kerry L; Bourassa, Martial G; Arnold, J Malcolm O; Buxton, Alfred E; Camm, A John; Connolly, Stuart J; Dubuc, Marc; Ducharme, Anique; Guerra, Peter G; Hohnloser, Stefan H; Lambert, Jean; Le Heuzey, Jean-Yves; O'Hara, Gilles; Pedersen, Ole Dyg; Rouleau, Jean-Lucien; Singh, Bramah N; Stevenson, Lynne Warner; Stevenson, William G; Thibault, Bernard; Waldo, Albert L

    2008-06-19

    It is common practice to restore and maintain sinus rhythm in patients with atrial fibrillation and heart failure. This approach is based in part on data indicating that atrial fibrillation is a predictor of death in patients with heart failure and suggesting that the suppression of atrial fibrillation may favorably affect the outcome. However, the benefits and risks of this approach have not been adequately studied. We conducted a multicenter, randomized trial comparing the maintenance of sinus rhythm (rhythm control) with control of the ventricular rate (rate control) in patients with a left ventricular ejection fraction of 35% or less, symptoms of congestive heart failure, and a history of atrial fibrillation. The primary outcome was the time to death from cardiovascular causes. A total of 1376 patients were enrolled (682 in the rhythm-control group and 694 in the rate-control group) and were followed for a mean of 37 months. Of these patients, 182 (27%) in the rhythm-control group died from cardiovascular causes, as compared with 175 (25%) in the rate-control group (hazard ratio in the rhythm-control group, 1.06; 95% confidence interval, 0.86 to 1.30; P=0.59 by the log-rank test). Secondary outcomes were similar in the two groups, including death from any cause (32% in the rhythm-control group and 33% in the rate-control group), stroke (3% and 4%, respectively), worsening heart failure (28% and 31%), and the composite of death from cardiovascular causes, stroke, or worsening heart failure (43% and 46%). There were also no significant differences favoring either strategy in any predefined subgroup. In patients with atrial fibrillation and congestive heart failure, a routine strategy of rhythm control does not reduce the rate of death from cardiovascular causes, as compared with a rate-control strategy. (ClinicalTrials.gov number, NCT00597077.) 2008 Massachusetts Medical Society

  18. [Failure rate and revision surgery in ossiculoplasty with Kurz titanium prosthesis].

    PubMed

    Nguyen, D Q; Lavieille, J P; Schmerber, S

    2004-01-01

    Despite its excellent biocompatibility, failures and in particular extrusion of the prosthesis have been described in ossiculoplasty with titanium prosthesis. Report our experience with revision ossicular recontruction in ossiculoplasty with Kurz prosthesis. Identify causes of failure in ossiculoplasty using the titanium prosthesis. Retrospective chart reviews were performed for 110 patients who had undergone titanium ossicular implants between November 1998 and 2002. All patients had undergone ossiculoplasty using titanium middle ear implants. Patients were divided into 2 groups: in group 1 patients underwent revision ossiculoplasty; in group 2 patients had a successful surgery at first stage. Anatomic and functional results have been studied in these two groups. Causes of failures were analysed. The overall failure rate was 20% (22/110). Twenty patients underwent revision ossiculoplasty. Nine primary failures were attributable to a short implant. Two extrusions were observed. At long term billow-up, the functional gain between the primary and revision ossiculoplasty was comparable. Revision ossiculoplasty is worthwhile for those patients who have failure of the titanium prosthesis in ossiculoplasty. A large cartilage graft interposition is necessary to prevent extrusion. The overall luxation rate observed in our series was mainly due to a too short prosthesis and we recommend now a reconstruction with longer prosthesis.

  19. Effect of yoga therapy on heart rate, blood pressure and cardiac autonomic function in heart failure.

    PubMed

    Krishna, Bandi Hari; Pal, Pravati; G K, Pal; J, Balachander; E, Jayasettiaseelon; Y, Sreekanth; M G, Sridhar; G S, Gaur

    2014-01-01

    It is well known that a hall mark of heart failure is adverse changes in autonomic function. Elevated blood pressure is a powerful predictor of congestive heart failure and other Cardiovascular Disease (CVD) outcomes. In this study, we planned to examine the effects of a 12 week yoga therapy on blood pressure, heart rate, heart rate variability, and rate pressure product (RPP). Out of 130 heart failure patients recruited for the study, 65 patients were randomly selected to receive 12 week yoga therapy along with standard medical therapy (yoga group). Other patients (n=65) received only standard medical therapy (control group). Heart rate, blood pressure, cardiac autonomic function (by short-term heart-rate variability analysis) and myocardial oxygen consumption (by RPP) were assessed before and after 12 weeks. In the yoga group, 44 patients and in the control group, 48 patients completed the study. There was a significant decrease in heart rate, blood pressure and RPP in yoga group compared to control group. Also, LFnu and LF-HF ratio decreased significantly and HFnu increased significantly in yoga group compared to control group. Twelve-week yoga therapy significantly improved the parasympathetic activity and decreased the sympathetic activity in heart failure patients (NYHA I&II).

  20. Repolarization heterogeneity and rate dependency in a canine rapid pacing model of heart failure.

    PubMed

    Lux, Robert L; Gettes, Leonard S

    2011-01-01

    Repolarization heterogeneity and rate dependency have long been established as factors contributing to arrhythmogenic risk. However, there are conflicting observations regarding the nature and extent of ventricular repolarization heterogeneity that complicate understanding of arrhythmogenic mechanisms. To explore these disparate findings, we studied ventricular repolarization heterogeneity and rate dependency in a canine, rapid pacing model of heart failure. We studied ventricular repolarization heterogeneity and rate dependency in 10 canine hearts (5 normal and 5 after 1 month of rapid pacing at 240 beats per minute) by analyzing 64 body surface electrocardiograms, 64 epicardial, and 190 intramural plunge electrograms. We estimated mean ventricular depolarization and repolarization times from R- and T-wave peaks of the root-mean-square electrocardiogram (body surface) and local depolarization and repolarization times using activation-recovery interval (ARI) methods from recordings obtained during a range of fixed rate pacing. In addition, we estimated local epicardial and transmural gradients of ARIs to assess cardiac locations of greatest spatial repolarization heterogeneity. We compared changes in repolarization at different rates between normal and heart failure hearts. Findings documented prolongation of repolarization, repolarization rate dependency, and increased repolarization gradients in the heart failure hearts compared with control as observed from body surface, epicardial, and transmural measurements. Maximum local epicardial and intramural ARI gradients were comparable both in heart failure and control hearts. Intramural ARI distributions tended to be more irregular in the heart failure hearts compared with the systematic epicardium to endocardium ARI increase observed in control animals. This study documented prolongation of repolarization, increase in both epicardial and transmural repolarization gradients, and irregularity of transmural

  1. The effects of inherent flaws on the time and rate dependent failure of adhesively bonded joints

    NASA Technical Reports Server (NTRS)

    Sancaktar, E.; Padgilwar, S.

    1982-01-01

    Inherent flaws, as well as the effects of rate and time, are shown by tests on viscoelastic adhesive-bonded single lap joints to be as critical in joint failure as environmental and stress concentration effects, with random inherent flaws and loading rate changes resulting in an up to 40% reduction in joint strength. It is also found that the asymptotic creep stress, below which no delayed failure may occur, may under creep loading be as much as 45% less than maximum adhesive strength. Attention is given to test results for the case of titanium-LARC-3 adhesive single-lap specimens.

  2. Components of Clinical Competence Ratings of Physicians: An Empirical Approach.

    ERIC Educational Resources Information Center

    Hojat, Mohammadreza; And Others

    1986-01-01

    The underlying structure of ratings of clinical competence was investigated. The instrument consisted of 33 statements on clinical behavior filled out by directors of medical education programs at postgraduate training institutions. It was concluded that ratings of clinical competence represent a multidimensional construct involving at least three…

  3. The long-term outcome of 755 consecutive constrained acetabular components in total hip arthroplasty examining the successes and failures.

    PubMed

    Berend, Keith R; Lombardi, Adolph V; Mallory, Thomas H; Adams, Joanne B; Russell, Jackie H; Groseth, Kari L

    2005-10-01

    Constrained acetabular components can treat or prevent instability after total hip arthroplasty (THA). We examine long-term results of 755 consecutive constrained THA in 720 patients (1986-1993; 62 primary, 59 conversion, 565 revision, 60 reimplantation, and 9 total femur). Eighty-three patients (88 THAs) were lost before 10-year follow-up, leaving 639 patients (667 THAs) available for study. Dislocation occurred in 117 hips (17.5%), in 37 (28.9%) of 128 constrained for recurrent dislocation, and 46 (28.2%) of 163 with dislocation history. Other reoperations were for aseptic loosening (51, 7.6% acetabular; 28, 4.2% stem; 16, 2.4% combined), infection (40, 6.0%), periprosthetic fracture (19, 2.8%), stem breakage (2, 0.3%), cup malposition (1, 0.1%), dissociated insert (1, 0.1%), dissociated femoral head (1, 0.1%), and impingement of 1 broken (0.1%) and 4 (0.6%) dissociated constraining rings. Although constrained acetabular components prevented recurrent dislocation in 71.1%, they should be used cautiously, with a 42.1% long-term failure rate observed in this series. Dislocation was common despite constraint with previous history as a significant risk.

  4. Pitfalls and Precautions When Using Predicted Failure Data for Quantitative Analysis of Safety Risk for Human Rated Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Hatfield, Glen S.; Hark, Frank; Stott, James

    2016-01-01

    Launch vehicle reliability analysis is largely dependent upon using predicted failure rates from data sources such as MIL-HDBK-217F. Reliability prediction methodologies based on component data do not take into account system integration risks such as those attributable to manufacturing and assembly. These sources often dominate component level risk. While consequence of failure is often understood, using predicted values in a risk model to estimate the probability of occurrence may underestimate the actual risk. Managers and decision makers use the probability of occurrence to influence the determination whether to accept the risk or require a design modification. The actual risk threshold for acceptance may not be fully understood due to the absence of system level test data or operational data. This paper will establish a method and approach to identify the pitfalls and precautions of accepting risk based solely upon predicted failure data. This approach will provide a set of guidelines that may be useful to arrive at a more realistic quantification of risk prior to acceptance by a program.

  5. Noninvasive ventilation for acute hypercapnic respiratory failure: intubation rate in an experienced unit.

    PubMed

    Contou, Damien; Fragnoli, Chiara; Córdoba-Izquierdo, Ana; Boissier, Florence; Brun-Buisson, Christian; Thille, Arnaud W

    2013-12-01

    Failure of noninvasive ventilation (NIV) is common in patients with COPD admitted to the ICU for acute hypercapnic respiratory failure (AHRF). We aimed to assess the rate of NIV failure and to identify early predictors of intubation under NIV in patients admitted for AHRF of all origins in an experienced unit. This was an observational cohort study using data prospectively collected over a 3-year period after the implementation of a nurse-driven NIV protocol in a 24-bed medical ICU of a French university hospital. Among 242 subjects receiving NIV for AHRF (P(aCO2) > 45 mm Hg), 67 had cardiogenic pulmonary edema (CPE), 146 had acute-on-chronic respiratory failure (AOCRF) (including 99 subjects with COPD and 47 with other chronic respiratory diseases), and 29 had non-AOCRF (mostly pneumonia). Overall, the rates of intubation and ICU mortality were respectively 15% and 5%. The intubation rates were 4% in CPE, 15% in AOCRF, and 38% in non-AOCRF (P < .001). After adjustment, non-AOCRF was independently associated with NIV failure, as well as acidosis (pH < 7.30) and severe hypoxemia (P(aO2)/F(IO2) ≤ 200 mm Hg) after 1 hour of NIV initiation, whereas altered consciousness on admission and ventilatory settings had no influence on outcome. With a nurse-driven NIV protocol, the intubation rate was reduced to 15% in patients receiving NIV for AHRF, with a mortality rate of only 5%. Whereas the risk of NIV failure is associated with hypoxemia and acidosis after initiation of NIV, it is also markedly influenced by the presence or absence of an underlying chronic respiratory disease.

  6. Accurate analytical modelling of cosmic ray induced failure rates of power semiconductor devices

    NASA Astrophysics Data System (ADS)

    Bauer, Friedhelm D.

    2009-06-01

    A new, simple and efficient approach is presented to conduct estimations of the cosmic ray induced failure rate for high voltage silicon power devices early in the design phase. This allows combining common design issues such as device losses and safe operating area with the constraints imposed by the reliability to result in a better and overall more efficient design methodology. Starting from an experimental and theoretical background brought forth a few yeas ago [Kabza H et al. Cosmic radiation as a cause for power device failure and possible countermeasures. In: Proceedings of the sixth international symposium on power semiconductor devices and IC's, Davos, Switzerland; 1994. p. 9-12, Zeller HR. Cosmic ray induced breakdown in high voltage semiconductor devices, microscopic model and possible countermeasures. In: Proceedings of the sixth international symposium on power semiconductor devices and IC's, Davos, Switzerland; 1994. p. 339-40, and Matsuda H et al. Analysis of GTO failure mode during d.c. blocking. In: Proceedings of the sixth international symposium on power semiconductor devices and IC's, Davos, Switzerland; 1994. p. 221-5], an exact solution of the failure rate integral is derived and presented in a form which lends itself to be combined with the results available from commercial semiconductor simulation tools. Hence, failure rate integrals can be obtained with relative ease for realistic two- and even three-dimensional semiconductor geometries. Two case studies relating to IGBT cell design and planar junction termination layout demonstrate the purpose of the method.

  7. Probabilistic exposure assessment model to estimate aseptic-UHT product failure rate.

    PubMed

    Pujol, Laure; Albert, Isabelle; Magras, Catherine; Johnson, Nicholas Brian; Membré, Jeanne-Marie

    2015-01-02

    Aseptic-Ultra-High-Temperature (UHT) products are manufactured to be free of microorganisms capable of growing in the food at normal non-refrigerated conditions at which the food is likely to be held during manufacture, distribution and storage. Two important phases within the process are widely recognised as critical in controlling microbial contamination: the sterilisation steps and the following aseptic steps. Of the microbial hazards, the pathogen spore formers Clostridium botulinum and Bacillus cereus are deemed the most pertinent to be controlled. In addition, due to a relatively high thermal resistance, Geobacillus stearothermophilus spores are considered a concern for spoilage of low acid aseptic-UHT products. A probabilistic exposure assessment model has been developed in order to assess the aseptic-UHT product failure rate associated with these three bacteria. It was a Modular Process Risk Model, based on nine modules. They described: i) the microbial contamination introduced by the raw materials, either from the product (i.e. milk, cocoa and dextrose powders and water) or the packaging (i.e. bottle and sealing component), ii) the sterilisation processes, of either the product or the packaging material, iii) the possible recontamination during subsequent processing of both product and packaging. The Sterility Failure Rate (SFR) was defined as the sum of bottles contaminated for each batch, divided by the total number of bottles produced per process line run (10(6) batches simulated per process line). The SFR associated with the three bacteria was estimated at the last step of the process (i.e. after Module 9) but also after each module, allowing for the identification of modules, and responsible contamination pathways, with higher or lower intermediate SFR. The model contained 42 controlled settings associated with factory environment, process line or product formulation, and more than 55 probabilistic inputs corresponding to inputs with variability

  8. Six-month bracket failure rate evaluation of a self-etching primer.

    PubMed

    Elekdag-Turk, Selma; Isci, Devrim; Turk, Tamer; Cakmak, Fethiye

    2008-04-01

    The aim of this study was to compare the clinical performance of a self-etching primer (SEP) with a conventional two-step etch and primer [conventional method (CM)]. The chair time required for bonding was also evaluated. Thirty-seven patients (14 males and 23 females) with a mean age of 16 years 5 months were included in the study. Six hundred and seventy-two brackets were bonded by one operator using a split-mouth design, with either SEP (Transbond Plus) or CM (Transbond XT). Bracket failure rates were estimated with respect to bonding procedure, dental arch, type of tooth (incisor, canine, and premolar), and gender. The results were evaluated using the chi-square test. The survival rate of the brackets was estimated with Kaplan-Meier analysis. Bracket survival distributions with respect to bonding procedure, dental arch, type of tooth, and patient gender were compared with a log-rank test. Bond failure interface was determined with the adhesive remnant index (ARI). The failure rates were 0.6 per cent for both bonding procedures. The failure and survival rates did not show significant differences between the bonding procedures, upper and lower dental arches, or gender. However, premolar brackets displayed a higher bond failure rate and a lower survival rate than incisor and canine brackets (P < 0.05). The mean bracket bonding time per tooth with SEP was significantly shorter than with CM (P < 0.001). No significant difference was observed for the ARI scores (P > 0.05). The results of this in vivo, randomized, cross-mouth clinical trial demonstrated a high survival rate with Transbond Plus. This finding indicates that SEP can be effectively used for bonding of orthodontic brackets.

  9. Generator exchange is associated with an increased rate of Sprint Fidelis lead failure.

    PubMed

    Lovelock, Joshua D; Patel, Ayesha; Mengistu, Andenet; Hoskins, Michael; El-Chami, Mikhael; Lloyd, Michael S; Leon, Angel; DeLurgio, David; Langberg, Jonathan J

    2012-10-01

    The Medtronic Sprint Fidelis defibrillator lead is at an increased risk for failure and was recalled in October 2007. Approximately 268,000 leads were implanted, and more than 100,000 patients still have active Fidelis leads. A number of studies have examined the rate and clinical predictors of lead failure, but none has addressed the effect of an implantable cardioverter-defibrillator generator exchange on subsequent lead failure. Although the manufacturer asserts that "Sprint Fidelis performance after device change-out is similar to lead performance without device change-out," published data are lacking. To assess the effect of implantable cardioverter-defibrillator generator exchange on the rate of Fidelis lead failure. A chart review was conducted in patients who underwent implantation of a Fidelis lead. Patients with a functioning Fidelis lead at generator exchange were compared with controls with leads implanted for a comparable amount of time not undergoing ICD replacement. A total of 1366 patients received a Fidelis lead prior to the recall, of which 479 were still actively followed. Seventy-two patients with a functioning lead underwent generator exchange without lead replacement. Following generator replacement, 15 leads failed. Sixty percent of the Fidelis leads failed within 3 months. Generator exchange increased the rate of lead failure compared with matched controls (20.8% vs 2.54%; P < .001). Generator exchange is associated with a higher than expected rate of Fidelis lead failure, often within 3 months. The risk-benefit ratio of Fidelis lead replacement at the time of generator exchange may be greater than appreciated. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  10. Stage I, grade III adenocarcinoma of the endometrium treated with surgery and irradiation. Sites of failure and correlation of failure rate with irradiation technique.

    PubMed

    Bedwinek, J; Galakatos, A; Camel, M; Kao, M S; Stokes, S; Perez, C

    1984-07-01

    Eighty-three patients treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO) and adjuvant irradiation for Stage I, grade III adenocarcinoma of the endometrium were reviewed. At 5 years, the overall survival was 71%, and the disease-free survival (excluding patients dying of intercurrent disease) was 79%. The failure rates for pelvis alone, pelvis plus distant, and distant alone were 4.8%, 4.8%, and 10.8%, respectively. The most common site of failure was the upper abdomen; 12% of all patients had a failure at this site, either alone or in conjunction with failure at another site. The 24% rate of failure in 50 patients receiving a preoperative implant and external irradiation was not significantly different from the 15% failure rate in 33 patients whose adjuvant irradiation consisted of a preoperative implant only. For the patients who had both an implant and external irradiation, the dose of external irradiation had no correlation with the rate of failure. In contrast, the number of milligram-hours delivered to the uterus by the preoperative implant had a strong inverse correlation with the rate of failure, both for patients receiving an implant only and for those receiving an implant plus external irradiation. The data suggest the following: (1) a high-intensity preoperative uterine implant may be an important adjunct to surgery; and (2) external pelvic irradiation in addition to the implant does not seem to be any more beneficial than an implant alone.

  11. Stage I, grade III adenocarcinoma of the endometrium treated with surgery and irradiation. Sites of failure and correlation of failure rate with irradiation technique

    SciTech Connect

    Bedwinek, J.; Galakatos, A.; Camel, M.; Kao, M.S.; Stokes, S.; Perez, C.

    1984-07-01

    Eighty-three patients treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO) and adjuvant irradiation for Stage I, grade III adenocarcinoma of the endometrium were reviewed. At 5 years, the overall survival was 71%, and the disease-free survival (excluding patients dying of intercurrent disease) was 79%. The failure rates for pelvis alone, pelvis plus distant, and distant alone were 4.8%, 4.8%, and 10.8%, respectively. The most common site of failure was the upper abdomen; 12% of all patients had a failure at this site, either alone or in conjunction with failure at another site. The 24% rate of failure in 50 patients receiving a preoperative implant and external irradiation was not significantly different from the 15% failure rate in 33 patients whose adjuvant irradiation consisted of a preoperative implant only. For the patients who had both an implant and external irradiation, the dose of external irradiation had no correlation with the rate of failure. In contrast, the number of milligram-hours delivered to the uterus by the preoperative implant had a strong inverse correlation with the rate of failure, both for patients receiving an implant only and for those receiving an implant plus external irradiation. The data suggest the following: (1) a high-intensity preoperative uterine implant may be an important adjunct to surgery; and (2) external pelvic irradiation in addition to the implant does not seem to be any more beneficial than an implant alone.

  12. Lower Provider Volume is Associated with Higher Failure Rates for Endoscopic Retrograde Cholangiopancreatography

    PubMed Central

    Coté, Gregory A.; Imler, Timothy D.; Xu, Huiping; Teal, Evgenia; French, Dustin D.; Imperiale, Thomas F.; Rosenman, Marc B.; Wilson, Jeffery; Hui, Siu L.; Sherman, Stuart

    2013-01-01

    Background Among physicians who perform endoscopic retrograde cholangiopancreatography (ERCP), the relationship between procedure volume and outcome is unknown. Objective Quantify the ERCP volume-outcome relationship by measuring provider-specific failure rates, hospitalization rates and other quality measures. Research Design Retrospective Cohort Subjects 16,968 ERCPs performed by 130 physicians between 2001-2011, identified in the Indiana Network for Patient Care (INPC) Measures Physicians were classified by their average annual INPC volume and stratified into low (<25/year) and high (≥25/year). Outcomes included failed procedures, defined as repeat ERCP, percutaneous transhepatic cholangiography or surgical exploration of the bile duct ≤ 7 days after the index procedure, hospitalization rates, and 30-day mortality. Results Among 15,514 index ERCPs, there were 1,163 (7.5%) failures; the failure rate was higher among low (9.5%) compared to high volume (5.7%) providers (p<0.001). A second ERCP within 7 days (a subgroup of failure rate) occurred more frequently when the original ERCP was performed by a low (4.1%) versus a high volume physician (2.3%, p=0.013). Patients were more frequently hospitalized within 24 hours when the ERCP was performed by a low (28.3%) vs. high volume physician (14.8%, p=0.002). Mortality within 30 days was similar (low – 1.9%, high – 1.9%). Among low volume physicians and after adjusting, the odds of having a failed procedure decreased 3.3% (95% CI 1.6-5.0%, p<0.001) with each additional ERCP performed per year. Conclusions Lower provider volume is associated with higher failure rate for ERCP, and greater need for post-procedure hospitalization. PMID:24226304

  13. Functional principal component analysis of glomerular filtration rate curves after kidney transplant.

    PubMed

    Dong, Jianghu J; Wang, Liangliang; Gill, Jagbir; Cao, Jiguo

    2017-01-01

    This article is motivated by some longitudinal clinical data of kidney transplant recipients, where kidney function progression is recorded as the estimated glomerular filtration rates at multiple time points post kidney transplantation. We propose to use the functional principal component analysis method to explore the major source of variations of glomerular filtration rate curves. We find that the estimated functional principal component scores can be used to cluster glomerular filtration rate curves. Ordering functional principal component scores can detect abnormal glomerular filtration rate curves. Finally, functional principal component analysis can effectively estimate missing glomerular filtration rate values and predict future glomerular filtration rate values.

  14. [The exercise training restores the heart rate variability in heart failure patients. A systematic review].

    PubMed

    Segovia, Victoria; Manterola, Carlos; González, Marcelo; Rodríguez-Núñez, Iván

    2017-01-05

    Cardiovascular diseases are an important cause of morbidity and mortality in the general population. In this sense the autonomic imbalance is the cornerstone of the physiopathology underlying the development of these diseases. The aim of this study was to determine the efficacy of exercise training on heart rate variability (HRV) in adult patients with chronic heart failure.

  15. Creating a Learning Flow: A Hybrid Course Model for High-Failure-Rate Math Classes

    ERIC Educational Resources Information Center

    Stevenson, Katherine; Zweier, Louis

    2011-01-01

    Higher education in the United States is facing a failure-rate crisis in entry-level mathematics courses. In this article, the authors describe an innovative, technology-enhanced hybrid course model that has significantly improved course completion and content mastery outcomes in general education (GE) mathematics courses. The model relies on five…

  16. High failure rate of nonoperative management of acute appendicitis with an appendicolith in children.

    PubMed

    Mahida, Justin B; Lodwick, Daniel L; Nacion, Kristine M; Sulkowski, Jason P; Leonhart, Karen L; Cooper, Jennifer N; Ambeba, Erica J; Deans, Katherine J; Minneci, Peter C

    2016-06-01

    The purpose of this study was to investigate the feasibility of nonoperative management of acute appendicitis in children with an appendicolith identified on preoperative imaging. We performed a prospective nonrandomized trial of nonoperative management of uncomplicated acute appendicitis with an appendicolith in children aged 7 to 17years. The primary outcome was the failure rate of nonoperative management, defined as having undergone an appendectomy. Early termination was set to occur if the lower limit of the 95% confidence interval of the failure rate was greater than 20% at 30days or 30% at 1year. Recruitment for this study was halted after enrollment of 14 patients (N=5 nonoperative; N=9 surgery). The failure rate of nonoperative management was 60% (3/5) at a median follow-up of 4.7months (IQR 1.0-7.6) with a 95% CI of 23%-88%. None of the three patients that failed nonoperative management had complicated appendicitis at the time of appendectomy, while six out of nine patients who chose surgery had complicated appendicitis (0/3 vs. 6/9, p=0.18). The trial was stopped for concerns over patient safety. Nonoperative management of acute appendicitis with an appendicolith in children resulted in an unacceptably high failure rate. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Creating a Learning Flow: A Hybrid Course Model for High-Failure-Rate Math Classes

    ERIC Educational Resources Information Center

    Stevenson, Katherine; Zweier, Louis

    2011-01-01

    Higher education in the United States is facing a failure-rate crisis in entry-level mathematics courses. In this article, the authors describe an innovative, technology-enhanced hybrid course model that has significantly improved course completion and content mastery outcomes in general education (GE) mathematics courses. The model relies on five…

  18. Failure rate and cosmesis of immediate tissue expander/implant breast reconstruction after postmastectomy irradiation.

    PubMed

    Baschnagel, Andrew M; Shah, Chirag; Wilkinson, J Ben; Dekhne, Nayana; Arthur, Douglas W; Vicini, Frank A

    2012-12-01

    This study reports the rate of breast reconstruction failure and cosmetic outcomes after postmastectomy radiation therapy (PMRT) with temporary tissue expanders (TEs) or implants in place. Ninety-four patients underwent mastectomy (93 unilateral, 1 bilateral; 95 cases total) and immediate TE reconstruction followed by PMRT. Ninety TEs and 5 permanent implants were irradiated. All patients received a dose of 5400 cGy given in 180-cGy fractions to the reconstructed breast. Twenty-one patients (22%) received tangents alone and 74 patients (78%) were treated with tangents and a supraclavicular field using a monoisocentric technique. Bolus was used in 91 patients (96%). Eighty-eight patients (93%) received chemotherapy and 78 patients (82%) received endocrine therapy. With a median follow-up of 24.1 months, 19 patients (20%) experienced failure of reconstruction. The 1-, 2-, and 3-year actuarial rate of reconstruction failure was 9.7%, 19.3%, and 25.5%, respectively. Infection was the most common cause of failure. Of the 19 failures, 8 patients underwent salvage procedures with flap reconstruction. Univariate analysis was performed examining age, chemotherapy use, hormone therapy use, use of a supraclavicular field, smoking status, diabetes, hypertension, and menopausal status. No risk factors were found to be associated with reconstruction failure. In patients who did not experience reconstruction failure, good/excellent cosmesis was observed in 75% of patients. In the current series of women with a high risk of locoregional recurrence, PMRT with a TE/implant in place provides good cosmesis in the majority of women, with an acceptable risk of expander or implant loss. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Failure rate of single dose methotrexate in managment of ectopic pregnancy.

    PubMed

    Sendy, Feras; AlShehri, Eman; AlAjmi, Amani; Bamanie, Elham; Appani, Surekha; Shams, Taghreed

    2015-01-01

    Background. One of the treatment modalities for ectopic pregnancy is methotrexate. The purpose of this study is to identify the failure rate of methotrexate in treating patients with ectopic pregnancy as well as the risk factors leading to treatment failure. Methods. A retrospective chart review of 225 patients who received methotrexate as a primary management option for ectopic pregnancy. Failure of single dose of methotrexate was defined as drop of BHCG level less than or equal to 14% in the seventh day after administration of methotrexate. Results. 225 patients had methotrexate. Most of the patients (151 (67%)) received methotrexate based on the following formula: f 50 mg X body surface area. Single dose of methotrexate was successful in 72% (162/225) of the patients. 28% (63/225) were labeled as failure of single dose of methotrexate because of suboptimal drop in BhCG. 63% (40/63) of failure received a second dose of methotrexate, and 37% (23/63) underwent surgical treatment. Among patient who received initial dose of methotrexate, 71% had moderate or severe pain, and 58% had ectopic mass size of more than 4 cm on ultrasound. Conclusion. Liberal use of medical treatment of ectopic pregnancy results in 71% success rate.

  20. Failure Rate of Single Dose Methotrexate in Managment of Ectopic Pregnancy

    PubMed Central

    Sendy, Feras; AlShehri, Eman; AlAjmi, Amani; Bamanie, Elham; Appani, Surekha; Shams, Taghreed

    2015-01-01

    Background. One of the treatment modalities for ectopic pregnancy is methotrexate. The purpose of this study is to identify the failure rate of methotrexate in treating patients with ectopic pregnancy as well as the risk factors leading to treatment failure. Methods. A retrospective chart review of 225 patients who received methotrexate as a primary management option for ectopic pregnancy. Failure of single dose of methotrexate was defined as drop of BHCG level less than or equal to 14% in the seventh day after administration of methotrexate. Results. 225 patients had methotrexate. Most of the patients (151 (67%)) received methotrexate based on the following formula: f 50 mg X body surface area. Single dose of methotrexate was successful in 72% (162/225) of the patients. 28% (63/225) were labeled as failure of single dose of methotrexate because of suboptimal drop in BhCG. 63% (40/63) of failure received a second dose of methotrexate, and 37% (23/63) underwent surgical treatment. Among patient who received initial dose of methotrexate, 71% had moderate or severe pain, and 58% had ectopic mass size of more than 4 cm on ultrasound. Conclusion. Liberal use of medical treatment of ectopic pregnancy results in 71% success rate. PMID:25861275

  1. Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides

    PubMed Central

    Handwerger, Alexander L.; Rempel, Alan W.; Skarbek, Rob M.; Roering, Joshua J.; Hilley, George E.

    2016-01-01

    Catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually, whereas slow-moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes. Surprisingly, both failure modes are displayed by nearby landslides (and individual landslides in different years) subjected to almost identical environmental conditions. Such observations have motivated the search for mechanisms that can cause slow-moving landslides to transition via runaway acceleration to catastrophic failure. A similarly diverse range of sliding behavior, including earthquakes and slow-slip events, occurs along tectonic faults. Our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions. Here, we describe landslide motion using a rate- and state-dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip. Our idealized, one-dimensional model reproduces both the displacement patterns observed in slow-moving landslides and the acceleration toward failure exhibited by catastrophic events. Catastrophic failure occurs only when the slip surface is characterized by rate-weakening friction and its lateral dimensions exceed a critical nucleation length h* that is shorter for higher effective stresses. However, landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure. Our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments. PMID:27573836

  2. Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides.

    PubMed

    Handwerger, Alexander L; Rempel, Alan W; Skarbek, Rob M; Roering, Joshua J; Hilley, George E

    2016-09-13

    Catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually, whereas slow-moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes. Surprisingly, both failure modes are displayed by nearby landslides (and individual landslides in different years) subjected to almost identical environmental conditions. Such observations have motivated the search for mechanisms that can cause slow-moving landslides to transition via runaway acceleration to catastrophic failure. A similarly diverse range of sliding behavior, including earthquakes and slow-slip events, occurs along tectonic faults. Our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions. Here, we describe landslide motion using a rate- and state-dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip. Our idealized, one-dimensional model reproduces both the displacement patterns observed in slow-moving landslides and the acceleration toward failure exhibited by catastrophic events. Catastrophic failure occurs only when the slip surface is characterized by rate-weakening friction and its lateral dimensions exceed a critical nucleation length [Formula: see text] that is shorter for higher effective stresses. However, landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure. Our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments.

  3. Flow and failure of an aluminium alloy from low to high temperature and strain rate

    NASA Astrophysics Data System (ADS)

    Sancho, Rafael; Cendón, David; Gálvez, Francisco

    2015-09-01

    The mechanical behaviour of an aluminium alloy is presented in this paper. The study has been carried out to analyse the flow and failure of the aluminium alloy 7075-T73. An experimental study has been planned performing tests of un-notched and notched tensile specimens at low strain rates using a servo-hydraulic machine. High strain rate tests have been carried out using the same geometry in a Hopkinson Split Tensile Bar. The dynamic experiments at low temperature were performed using a cryogenic chamber, and the high temperature ones with a furnace, both incorporated to the Hopkinson bar. Testing temperatures ranged from - 50 ∘C to 100 ∘C and the strain rates from 10-4 s-1 to 600 s-1. The material behaviour was modelled using the Modified Johnson-Cook model and simulated using LS-DYNA. The results show that the Voce type of strain hardening is the most accurate for this material, while the traditional Johnson-Cook is not enough accurate to reproduce the necking of un-notched specimens. The failure criterion was obtained by means of the numerical simulations using the analysis of the stress triaxiality versus the strain to failure. The diameters at the failure time were measured using the images taken with an image camera, and the strain to failure was computed for un-notched and notched specimens. The numerical simulations show that the analysis of the evolution of the stress triaxiality is crucial to achieve accurate results. A material model using the Modified Johnson-Cook for flow and failure is proposed.

  4. Drug eluting biliary stents to decrease stent failure rates: A review of the literature

    PubMed Central

    Shatzel, Joseph; Kim, Jisoo; Sampath, Kartik; Syed, Sharjeel; Saad, Jennifer; Hussain, Zilla H; Mody, Kabir; Pipas, J Marc; Gordon, Stuart; Gardner, Timothy; Rothstein, Richard I

    2016-01-01

    Biliary stenting is clinically effective in relieving both malignant and non-malignant obstructions. However, there are high failure rates associated with tumor ingrowth and epithelial overgrowth as well as internally from biofilm development and subsequent clogging. Within the last decade, the use of prophylactic drug eluting stents as a means to reduce stent failure has been investigated. In this review we provide an overview of the current research on drug eluting biliary stents. While there is limited human trial data regarding the clinical benefit of drug eluting biliary stents in preventing stent obstruction, recent research suggests promise regarding their safety and potential efficacy. PMID:26839648

  5. Twelve-month bracket failure rate with amorphous calcium phosphate bonding system.

    PubMed

    Hammad, Shaza M; El Banna, Mai S; Elsaka, Shaymaa E

    2013-10-01

    The aim of the study was to compare the survival rate of orthodontic brackets over a 12-month period using amorphous calcium phosphate (ACP) bonding system with a conventional adhesive (CA). In 30 patients with a mean age of 15 years 7 months, one operator bonded 138 brackets with a split-mouth design, using a resin-based CA and ACP-containing adhesive. The survival rate of the brackets was estimated by Kaplan-Meier analysis. Bracket survival distributions with respect to bonding procedure, dental arch, type of tooth (incisor, canine, and premolar), and patients' gender were compared using the log-rank test. The bond failure interface was determined using the Adhesive Remnant Index (ARI). The bond failure rates of the CA and ACP-containing adhesive were 2.67 and 3.8 per cent, respectively. There was no significant difference between the failure rates of ACP and CA-bonded systems (P > 0.05). Survival rates did not show significant differences between the upper and lower dental arches (P > 0.05). Lower survival rates were found for canine and premolar teeth than incisors (P < 0.05). Bond failure rates were higher for males than females (P < 0.05). There was a significant difference for ARI scores between the adhesive materials (P = 0.028); more of the ACP-based adhesive was left on the tooth at debond. ACP-containing adhesive can be effectively used to bond orthodontic brackets and can serve as a practicable alternative to the conventional bonding adhesives.

  6. Solving Component Structural Dynamic Failures Due to Extremely High Frequency Structural Response on the Space Shuttle Program

    NASA Technical Reports Server (NTRS)

    Frady, Greg; Nesman, Thomas; Zoladz, Thomas; Szabo, Roland

    2010-01-01

    For many years, the capabilities to determine the root-cause failure of component failures have been limited to the analytical tools and the state of the art data acquisition systems. With this limited capability, many anomalies have been resolved by adding material to the design to increase robustness without the ability to determine if the design solution was satisfactory until after a series of expensive test programs were complete. The risk of failure and multiple design, test, and redesign cycles were high. During the Space Shuttle Program, many crack investigations in high energy density turbomachines, like the SSME turbopumps and high energy flows in the main propulsion system, have led to the discovery of numerous root-cause failures and anomalies due to the coexistences of acoustic forcing functions, structural natural modes, and a high energy excitation, such as an edge tone or shedding flow, leading the technical community to understand many of the primary contributors to extremely high frequency high cycle fatique fluid-structure interaction anomalies. These contributors have been identified using advanced analysis tools and verified using component and system tests during component ground tests, systems tests, and flight. The structural dynamics and fluid dynamics communities have developed a special sensitivity to the fluid-structure interaction problems and have been able to adjust and solve these problems in a time effective manner to meet budget and schedule deadlines of operational vehicle programs, such as the Space Shuttle Program over the years.

  7. Experimental Study of Solder/Copper Interface Failure Under Varying Strain Rates

    DTIC Science & Technology

    2011-03-01

    subjected to dynamic axial loads at strain rates between 10.0 s-1 and 0.05 s-1. The copper is alloy 101 and the lead-free solder has a composition of 96...OF SOLDER/COPPER INTERFACE FAILURE UNDER VARYING STRAIN RATES by Andrew Michael Luteran March 2011 Thesis Advisor: Young W. Kwon Second...tin and 4% silver. The tests results revealed that as the strain rate increases so do the ultimate and yield strengths but the elastic modulus

  8. Failure mechanisms in CAS/SiC composite as a function of the strain rate

    SciTech Connect

    Martin, A.; Puente, I.; Sanchez, J.M. |

    1995-12-01

    Room temperature tensile tests at variable strain-rates in a Nicalon{reg_sign}/CAS continuous fibre reinforced glass ceramic matrix composite, with cross-ply architecture [(0/90){sub 3}]{sub s}, are presented and analysed with reference to deformation and failure mechanisms (matrix cracking, fibre debonding, pullout, etc.). The experimental strain rates used range from 10{sup -4} to 10{sup +1} s{sup -1}. It is observed that, within the examined experimental range, the strain energy density increases as the strain rate increases, even when fibre pullout extent decreases. This is explained by a larger matrix degradation.

  9. Female sterilization: a review of methods, morbidity, failure rates and medicolegal aspects.

    PubMed

    Newton, J; Mccormack, J

    1990-09-01

    Introduced in England in 1967, laparoscopic sterilization has effected a radical change in female sterilization which 1st consisted of electrocoagulation of the Fallopian tubes. Mechanical methods have since basically replaced electrocoagulation, such as tubal rings and clips. In the mid 1970s, the Filshie clip emerged and has since become the most common form of laparoscopic technique. Research demonstrates that it has a low incidence of surgical difficulty, low morbidity, and low failure rates. Other means of accessing the tubes include minilaparotomy and culdotomy (common in India). Generally women undergo general anesthesia for sterilization. Overall morbidity and mortality (10/10,000) following female sterilization is low. Early morbidity may include surgical complications (bleeding during surgery or torn tubes), technical failure (.6-1% for various laparoscopic techniques), and hemorrhage. Few long term follow up studies have taken place, but possible long term adverse effects are abdominal pain, pain during sexual intercourse, changes in menstruation, and a need for gynecologic surgery. Failure rates vary depending on the method, surgical approach, surgeon skill, and type of patient. The highest failure rate of a laparoscopic or minilaparotomy approach lies with culdotomy (7-15/1000) and the lowest with thermal coagulation (1/1000). The laparotomy approach may be as high as 14/1000. Between 1970-1980, the number of litigations have increased because of sterilization failure. These cases have showed a consistent pattern: insufficient patient information, poor notes with no indications of any counseling, little written information for patients to support verbal counseling, and illegible and meager operation notes.

  10. Evaluation of cephalexin failure rates in morbidly obese patients with cellulitis.

    PubMed

    Kaufman, K R; Thurber, K M; O'Meara, J G; Langworthy, D R; Kashiwagi, D T

    2016-08-01

    Identification of adequate antimicrobial dosing regimens for morbidly obese patients is essential given the simultaneous increase in morbid obesity and cellulitis prevalence in recent years. Insufficient data currently exist to describe the effectiveness of extrapolating traditional antibiotic dosing strategies to morbidly obese patients with cellulitis. The primary objective of this study was to compare therapeutic failure rates in non-obese and morbidly obese patients with cellulitis when treated with cephalexin at standard dosing. This was a single-centre, retrospective cohort analysis. Adult patients hospitalized or under inpatient observation at a 1265-bed academic medical centre who received cephalexin monotherapy for non-purulent cellulitis from 2005 to 2015 were evaluated for inclusion. Patients were divided into two cohorts based on body mass index (BMI), where BMI <30 kg/m(2) was defined as non-obese and BMI ≥40 kg/m(2) as morbidly obese. Patients with critical risk factors for purulent or polymicrobial cellulitis were excluded. The primary outcome, therapeutic failure, was defined as a need for extended or additional antimicrobial therapy, surgical intervention, emergency department visit, or re-hospitalization within two to thirty days after cephalexin initiation. A total of 94 patients (69 non-obese and 25 morbidly obese) met inclusion and exclusion criteria, which was below the estimated sample size needed to reach desired power. The rate of therapeutic failure in the morbidly obese group was similar to the non-obese group (20% vs. 14·5%, P = 0·53). Patients most commonly had extended or additional antibiotics prescribed in response to therapeutic failure with cephalexin. Cephalexin failure rates for cellulitis did not differ statistically between morbidly obese and non-obese patients. The underpowered nature of this study is a limitation. Until further study with a larger sample size is completed, empiric adjustment of cephalexin dosing based

  11. Gamete cytogenetic study in couples with implantation failure: aneuploidy rate is increased in both couple members

    PubMed Central

    Hammoud, I.; Molina-Gomes, D.; Wainer, R.; Bergere, M.; Albert, M.; Bailly, M.; de Mazancourt, P.; Selva, J.

    2008-01-01

    Purpose Implantation failure is known to be associated with an increased risk of aneuploidy in embryos, a situation leading to a pre-implantation genetic screening, not allowed in different countries like France. Our aim was to evaluate the gamete aneuploidy incidence in this context, using first polar body and spermatozoa aneuploidy screening. Methods Three groups were considered: 11 couples with pregnancy obtained after IVF for female infertility (group 1); 20 couples with pregnancy obtained after IVF for male infertility (group 2); and 35 couples with implantation failure (group 3). In group 3, 28 couples treated by ICSI volunteered for first polar body analysis (PB1). Results Spermatozoa aneuploidy rate was increased in groups 2 (1.6%) and 3 (2.1%) in comparison to group 1 (0.6%). PB1 aneuploidy rate was 35.4% in group 3. Finally, eight couples (32%) had no particular chromosomal risk in gametes, 15/25 (60%) presented an increased spermatic (>2%) or oocyte (>1/3) aneuploidy rate, and 2/25 (8%) had both. Conclusion Those results confirm that implantation failure has a heterogeneous origin, that gamete chromosome abnormality rate is one of the major contributing factors, and that 1st Polar body and spermatozoa aneuploidy screening or pre-implantation genetics screening may be indicated for these couples. PMID:18972203

  12. Relationship between Sponsorship and Failure Rate of Dental Implants: A Systematic Approach

    PubMed Central

    Popelut, Antoine; Valet, Fabien; Fromentin, Olivier; Thomas, Aurélie; Bouchard, Philippe

    2010-01-01

    Background The number of dental implant treatments increases annually. Dental implants are manufactured by competing companies. Systematic reviews and meta-analysis have shown a clear association between pharmaceutical industry funding of clinical trials and pro-industry results. So far, the impact of industry sponsorship on the outcomes and conclusions of dental implant clinical trials has never been explored. The aim of the present study was to examine financial sponsorship of dental implant trials, and to evaluate whether research funding sources may affect the annual failure rate. Methods and Findings A systematic approach was used to identify systematic reviews published between January 1993 and December 2008 that specifically deal with the length of survival of dental implants. Primary articles were extracted from these reviews. The failure rate of the dental implants included in the trials was calculated. Data on publication year, Impact Factor, prosthetic design, periodontal status reporting, number of dental implants included in the trials, methodological quality of the studies, presence of a statistical advisor, and financial sponsorship were extracted by two independent reviewers (kappa  = 0.90; CI95% [0.77–1.00]). Univariate quasi-Poisson regression models and multivariate analysis were used to identify variables that were significantly associated with failure rates. Five systematic reviews were identified from which 41 analyzable trials were extracted. The mean annual failure rate estimate was 1.09%.(CI95% [0.84–1.42]). The funding source was not reported in 63% of the trials (26/41). Sixty-six percent of the trials were considered as having a risk of bias (27/41). Given study age, both industry associated (OR = 0.21; CI95% [0.12–0.38]) and unknown funding source trials (OR = 0.33; (CI95% [0.21–0.51]) had a lower annual failure rates compared with non-industry associated trials. A conflict of interest statement was disclosed in 2

  13. Relationship between sponsorship and failure rate of dental implants: a systematic approach.

    PubMed

    Popelut, Antoine; Valet, Fabien; Fromentin, Olivier; Thomas, Aurélie; Bouchard, Philippe

    2010-04-21

    The number of dental implant treatments increases annually. Dental implants are manufactured by competing companies. Systematic reviews and meta-analysis have shown a clear association between pharmaceutical industry funding of clinical trials and pro-industry results. So far, the impact of industry sponsorship on the outcomes and conclusions of dental implant clinical trials has never been explored. The aim of the present study was to examine financial sponsorship of dental implant trials, and to evaluate whether research funding sources may affect the annual failure rate. A systematic approach was used to identify systematic reviews published between January 1993 and December 2008 that specifically deal with the length of survival of dental implants. Primary articles were extracted from these reviews. The failure rate of the dental implants included in the trials was calculated. Data on publication year, Impact Factor, prosthetic design, periodontal status reporting, number of dental implants included in the trials, methodological quality of the studies, presence of a statistical advisor, and financial sponsorship were extracted by two independent reviewers (kappa = 0.90; CI(95%) [0.77-1.00]). Univariate quasi-Poisson regression models and multivariate analysis were used to identify variables that were significantly associated with failure rates. Five systematic reviews were identified from which 41 analyzable trials were extracted. The mean annual failure rate estimate was 1.09%.(CI(95%) [0.84-1.42]). The funding source was not reported in 63% of the trials (26/41). Sixty-six percent of the trials were considered as having a risk of bias (27/41). Given study age, both industry associated (OR = 0.21; CI(95%) [0.12-0.38]) and unknown funding source trials (OR = 0.33; (CI(95%) [0.21-0.51]) had a lower annual failure rates compared with non-industry associated trials. A conflict of interest statement was disclosed in 2 trials. When controlling for other factors, the

  14. A comparison of WMT, CARB, and TOMM failure rates in non-head injury disability claimants.

    PubMed

    Gervais, Roger O; Rohling, Martin L; Green, Paul; Ford, Wendy

    2004-06-01

    Two-alternative forced-choice procedures have been the most widely employed for detecting incomplete effort and exaggeration of cognitive impairment. However, it cannot be assumed that different symptom validity tests (SVTs) are of equal sensitivity. In this study, 519 claimants referred for disability or personal injury related assessments were administered three SVTs, one based on digit recognition (Computerized Assessment of Response Bias, CARB), one using pictorial stimuli (Test of Memory Malingering, TOMM) and one employing verbal recognition memory (Word Memory Test, WMT). More than twice as many people failed the WMT than TOMM. CARB failure rates were intermediate between those on the other two tests. Thus, tests of recognition memory using digits, pictorial stimuli or verbal stimuli, all of which are objectively extremely easy tasks, resulted in widely different failure rates. This suggests that, while these tests may be highly specific, they vary substantially in their sensitivity to response bias. Copyright 2003 National Academy of Neuropsychology

  15. Deformation and failure of OFHC copper under high strain rate shear compression

    NASA Astrophysics Data System (ADS)

    Ruggiero, Andrew; Testa, Gabriel; Bonora, Nicola; Iannitti, Gianluca; Persechino, Italo; Colliander, Magnus Hörnqvist

    2017-01-01

    Hat-shaped specimen geometries were developed to generate high strain, high-strain-rates deformation under prescribed conditions. These geometries offer also the possibility to investigate the occurrence of ductile rupture under low or negative stress triaxiality, where most failure models fail. In this work, three tophat geometries were designed, by means of extensive numerical simulation, to obtain desired stress triaxiality values within the shear region that develops across the ligament. Material failure was simulated using the Continuum Damage Model (CDM) formulation with a unilateral condition for damage accumulation and validated by comparing with quasi-static and high strain rate compression tests results on OFHC copper. Preliminary results seem to indicate that ductile tearing initiates at the specimen corner location where positive stress triaxiality occurs because of local rotation and eventually propagates along the ligament.

  16. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    SciTech Connect

    Brown, Eric N; Rae, Philip J; Dattelbaum, Dana M; Stahl, David B

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  17. Heart Rate at Hospital Discharge in Patients With Heart Failure Is Associated With Mortality and Rehospitalization

    PubMed Central

    Laskey, Warren K.; Alomari, Ihab; Cox, Margueritte; Schulte, Phillip J.; Zhao, Xin; Hernandez, Adrian F.; Heidenreich, Paul A.; Eapen, Zubin J.; Yancy, Clyde; Bhatt, Deepak L.; Fonarow, Gregg C.

    2015-01-01

    Background Whether heart rate upon discharge following hospitalization for heart failure is associated with long‐term adverse outcomes and whether this association differs between patients with sinus rhythm (SR) and atrial fibrillation (AF) have not been well studied. Methods and Results We conducted a retrospective cohort study from clinical registry data linked to Medicare claims for 46 217 patients participating in Get With The Guidelines®–Heart Failure. Cox proportional‐hazards models were used to estimate the association between discharge heart rate and all‐cause mortality, all‐cause readmission, and the composite outcome of mortality/readmission through 1 year. For SR and AF patients with heart rate ≥75, the association between heart rate and mortality (expressed as hazard ratio [HR] per 10 beats‐per‐minute increment) was significant at 0 to 30 days (SR: HR 1.30, 95% CI 1.22 to 1.39; AF: HR 1.23, 95% CI 1.16 to 1.29) and 31 to 365 days (SR: HR 1.15, 95% CI 1.12 to 1.20; AF: HR 1.05, 95% CI 1.01 to 1.08). Similar associations between heart rate and all‐cause readmission and the composite outcome were obtained for SR and AF patients from 0 to 30 days but only in the composite outcome for SR patients over the longer term. The HR from 0 to 30 days exceeded that from 31 to 365 days for both SR and AF patients. At heart rates <75, an association was significant for mortality only for both SR and AF patients. Conclusions Among older patients hospitalized with heart failure, higher discharge heart rate was associated with increased risks of death and rehospitalization, with higher risk in the first 30 days and for SR compared with AF. PMID:25904590

  18. Analysis of field usage failure rate data for plastic encapsulated solid state devices

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Survey and questionnaire techniques were used to gather data from users and manufacturers on the failure rates in the field of plastic encapsulated semiconductors. It was found that such solid state devices are being successfully used by commercial companies which impose certain screening and qualification procedures. The reliability of these semiconductors is now adequate to support their consideration in NASA systems, particularly in low cost systems. The cost of performing necessary screening for NASA applications was assessed.

  19. Rabies Vaccination: Higher Failure Rates in Imported Dogs than in those Vaccinated in Italy.

    PubMed

    Rota Nodari, E; Alonso, S; Mancin, M; De Nardi, M; Hudson-Cooke, S; Veggiato, C; Cattoli, G; De Benedictis, P

    2017-03-01

    The current European Union (EU) legislation decrees that pets entering the EU from a rabies-infected third country have to obtain a satisfactory virus-neutralizing antibody level, while those moving within the EU require only rabies vaccination as the risk of moving a rabid pet within the EU is considered negligible. A number of factors driving individual variations in dog vaccine response have been previously reported, including a high rate of vaccine failure in puppies, especially those subject to commercial transport. A total of 21 001 observations collected from dogs (2006-2012) vaccinated in compliance with the current EU regulations were statistically analysed to assess the effect of different risk factors related to rabies vaccine efficacy. Within this framework, we were able to compare the vaccination failure rate in a group of dogs entering the Italian border from EU and non-EU countries to those vaccinated in Italy prior to international travel. Our analysis identified that cross-breeds and two breed categories showed high vaccine success rates, while Beagles and Boxers were the least likely to show a successful response to vaccination (88.82% and 90.32%, respectively). Our analysis revealed diverse performances among the commercially available vaccines, in terms of serological peak windows, and marked differences according to geographical area. Of note, we found a higher vaccine failure rate in imported dogs (13.15%) than in those vaccinated in Italy (5.89%). Our findings suggest that the choice of vaccine may influence the likelihood of an animal achieving a protective serological level and that time from vaccination to sampling should be considered when interpreting serological results. A higher vaccine failure in imported compared to Italian dogs highlights the key role that border controls still have in assessing the full compliance of pet movements with EU legislation to minimize the risk of rabies being reintroduced into a disease-free area.

  20. Cardiac resynchronization therapy: implant rates, temporal trends and relationships with heart failure epidemiology.

    PubMed

    Boriani, Giuseppe; Berti, Elena; Belotti, Laura Maria Beatrice; Biffi, Mauro; Carboni, Angelo; Bandini, Alberto; Casali, Edoardo; Tomasi, Corrado; Toselli, Tiziano; Baraldi, Paolo; Bottoni, Nicola; Barbato, Gaetano; Sassone, Biagio

    2014-02-01

    Consensus guidelines define indications for cardiac resynchronization therapy (CRT), but the variability in implant rates in 'real world' clinical practice, as well as the relationship with the epidemiology of heart failure are not defined. In Emilia-Romagna, an Italian region with around 4.4 million inhabitants, a registry was instituted to collect data on implanted devices for CRT, with (CRT-D) or without defibrillation (CRT-P) capabilities. Data from all consecutive patients resident in this region who underwent a first implant of a CRT device in years 2006-2010 were collected and standardized (considering each of the nine provinces of the region). The number of CRT implants increased progressively, with a 71% increase in 2010 compared to 2006. Between 84 and 90% of implants were with CRT-D devices. The variability in standardized implant rates among the provinces was substantial and the ratio between the provinces with the highest and the lowest implant rates was always greater than 2. Considering prevalent cases of heart failure in the period 2006-2010, the proportion of patients implanted with CRT per year ranged between 0.23 and 0.30%. The application in 'real world' clinical practice of CRT in heart failure is quite heterogeneous, with substantial variability even among areas belonging to the same region, with the need to make the access to this treatment more equitable. Despite the increased use of CRT, its overall rate of adoption is low, if a population of prevalent heart failure patients is selected on the basis of administrative data on hospitalizations.

  1. Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides

    NASA Astrophysics Data System (ADS)

    Handwerger, Alexander L.; Rempel, Alan W.; Skarbek, Rob M.; Roering, Joshua J.; Hilley, George E.

    2016-09-01

    Catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually, whereas slow-moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes. Surprisingly, both failure modes are displayed by nearby landslides (and individual landslides in different years) subjected to almost identical environmental conditions. Such observations have motivated the search for mechanisms that can cause slow-moving landslides to transition via runaway acceleration to catastrophic failure. A similarly diverse range of sliding behavior, including earthquakes and slow-slip events, occurs along tectonic faults. Our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions. Here, we describe landslide motion using a rate- and state-dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip. Our idealized, one-dimensional model reproduces both the displacement patterns observed in slow-moving landslides and the acceleration toward failure exhibited by catastrophic events. Catastrophic failure occurs only when the slip surface is characterized by rate-weakening friction and its lateral dimensions exceed a critical nucleation length h*h* that is shorter for higher effective stresses. However, landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure. Our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments.

  2. Failure rate of single-unit restorations on posterior vital teeth: A systematic review.

    PubMed

    Afrashtehfar, Kelvin I; Emami, Elham; Ahmadi, Motahareh; Eilayyan, Owis; Abi-Nader, Samer; Tamimi, Faleh

    2017-03-01

    No knowledge synthesis exists concerning when to use a direct restoration versus a complete-coverage indirect restoration in posterior vital teeth. The purpose of this systematic review was to identify the failure rate of conventional single-unit tooth-supported restorations in posterior permanent vital teeth as a function of remaining tooth structure. Four databases were searched electronically, and 8 selected journals were searched manually up to February 2015. Clinical studies of tooth-supported single-unit restorative treatments with a mean follow-up period of at least 3 years were selected. The outcome measured was the restorations' clinical or radiological failure. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, the Cochrane Collaboration procedures for randomized control trials, the Strengthening the Reporting of Observational Studies in Epidemiology criteria for observational studies, 2 reviewers independently applied eligibility criteria, extracted data, and assessed the quality of the evidence of the included studies using the American Association of Critical Care Nurses' system. The weighted-mean group 5-year failure rates of the restorations were reported according to the type of treatment and remaining tooth structure. A metaregression model was used to assess the correlation between the number of remaining tooth walls and the weighted-mean 5-year failure rates. Five randomized controlled trials and 9 observational studies were included and their quality ranged from low to moderate. These studies included a total of 358 crowns, 4804 composite resins, and 303582 amalgams. Data obtained from the randomized controlled trials showed that, regardless of the amount of remaining tooth structure, amalgams presented better outcomes than composite resins. Furthermore, in teeth with fewer than 2 remaining walls, high-quality observational studies demonstrated that crowns were better than amalgams. A clear inverse

  3. Effect of electromagnetic-navigated shunt placement on failure rates: a prospective multicenter study.

    PubMed

    Hayhurst, Caroline; Beems, Tjemme; Jenkinson, Michael D; Byrne, Patricia; Clark, Simon; Kandasamy, Jothy; Goodden, John; Nandoe Tewarie, Rishi D S; Mallucci, Conor L

    2010-12-01

    As many as 40% of shunts fail in the first year, mainly due to proximal obstruction. The role of catheter position on failure rates has not been clearly demonstrated. The authors conducted a prospective cohort study of navigated shunt placement compared with standard blind shunt placement at 3 European centers to assess the effect on shunt failure rates. All adult and pediatric patients undergoing de novo ventriculoperitoneal shunt placement were included (patients with slit ventricles were excluded). The first cohort underwent standard shunt placement using anatomical landmarks. All centers subsequently adopted electromagnetic (EM) navigation for routine shunt placements, forming the second cohort. Catheter position was graded on postoperative CT in both groups using a 3-point scale developed for this study: (1) optimal position free-floating in CSF; (2) touching choroid or ventricular wall; or (3) intraparenchymal. Episodes and type of shunt revision were recorded. Early shunt failure was defined as that occurring within 30 days of surgery. Patients with shunts were followed-up for 12 months in the standard group, for a median of 6 months in the EM-navigated group, or until shunt failure. A total of 75 patients were included in the study, 41 with standard shunts and 34 with EM-navigated shunts. Seventy-four percent of navigated shunts were Grade 1 compared with 37% of the standard shunts (p=0.001, chi-square test). There were no Grade 3 placements in the navigated group, but 8 in the standard group, and 75% of these failed. Early shunt failure occurred in 9 patients in the standard group and in 2 in the navigated group, reducing the early revision rate from 22 to 5.9% (p=0.048, Fisher exact test). Early shunt failures were due to proximal obstruction in 78% of standard shunts (7 of 9) and in 50% of EM-navigated shunts (1 of 2). Noninvasive EM image guidance in shunt surgery reduces poor shunt placement, resulting in a significant decrease in the early shunt

  4. The failure rate of NHS funded molar endodontic treatment delivered in general dental practice.

    PubMed

    Tickle, M; Milsom, K; Qualtrough, A; Blinkhorn, F; Aggarwal, V R

    2008-03-08

    To describe the quality and record the outcomes of root canal therapy on mandibular, first permanent molar teeth provided by GDPs working according to NHS contracts. Descriptive, retrospective cohort study. Twelve general dental practices in Salford, North West England. All patients aged 20-60 years attending the practices who had received a NHS-funded root filling in a mandibular first permanent molar between January 1998 and December 2003. The radiographic quality of root fillings in the teeth was assessed by an endodontic specialist and categorised into optimal, suboptimal and teeth which had no radiograph, or an unreadable radiograph. Teeth were also dichotomised into those restored with a crown and those restored with an intracoronal restoration. Failure as an outcome was defined as if a tooth was extracted, the root filling was replaced or periradicular surgery was performed on the tooth. Crude failure rates per 100 years were calculated for optimally, sub-optimally root filled teeth and for those with no or an unreadable radiograph, and according to how the tooth was coronally restored. Survival was assessed using Kaplan-Meier curves and Cox proportional hazards were used to determine factors linked with increased failures. One hundred and seventy-four teeth were included in the study, of which 16 failed. The crude failure rates per 100 years with a root filled tooth were very low and differed little (p = 0.9699) for optimally (2.6), sub-optimally (2.5) root filled teeth and for those with no or an unreadable radiograph (2.9), with approximately one in 37 root filled mandibular first molar teeth failing each year. The majority of root fillings fail within the first two years (N = 10, 62.5%). Some 67 teeth (38.5%) were restored with a crown, none of which failed during the follow up period compared to those with a plastic restoration (p = 0.0004). The very low failure rates have significant implications for the design of research studies investigating

  5. Predictions of High Strain Rate Failure Modes in Layered Aluminum Composites

    NASA Astrophysics Data System (ADS)

    Khanikar, Prasenjit; Zikry, M. A.

    2014-01-01

    A dislocation density-based crystalline plasticity formulation, specialized finite-element techniques, and rational crystallographic orientation relations were used to predict and characterize the failure modes associated with the high strain rate behavior of aluminum layered composites. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary distributions. Different layer arrangements were investigated for high strain rate applications and the optimal arrangement was with the high toughness 2139 layer on the bottom, which provided extensive shear strain localization, and the high strength 2195 layer on the top for high strength resistance The layer thickness of the bottom high toughness layer also affected the bending behavior of the roll-bonded interface and the potential delamination of the layers. Shear strain localization, dynamic cracking, and delamination are the mutually competing failure mechanisms for the layered metallic composite, and control of these failure modes can be used to optimize behavior for high strain rate applications.

  6. Clinical evaluation of the failure rate of metallic brackets bonded with orthodontic composites.

    PubMed

    Romano, Fábio Lourenço; Valério, Rodrigo Alexandre; Gomes-Silva, Jaciara Miranda; Ferreira, José Tarcísio Lima; Faria, Gisele; Borsatto, Maria Cristina

    2012-01-01

    The purpose of the present study was to evaluate in vivo the failure rate of metallic brackets bonded with two orthodontic composites. Nineteen patients with ages ranging from 10.5 to 38.7 years needing corrective orthodontic treatment were selected for study. The enamel surfaces from second premolars to second premolars were treated with Transbond Plus-Self Etching Primer (3M Unitek). Next, 380 orthodontic brackets were bonded on maxillary and mandibular teeth, as follows: 190 with Transbond XT composite (3M Unitek) (control) and 190 with Transbond Plus Color Change (3M Unitek) (experimental) in contralateral quadrants. The bonded brackets were light cured for 40 s, and initial alignment archwires were inserted. Bond failure rates were recorded over a six-month period. At the end of the evaluation, six bond failures occurred, three for each composite. Kaplan-Meyer method and log-rank test (Mantel-Cox) was used for statistical analysis, and no statistically significant difference was found between the materials (p=0.999). Both Transbond XT and Transbond Plus Color Change composites had low debonding rates over the study period.

  7. The Relationships between Support System Failures and College Students' Ratings of Self and Family: Do They Vary across Family Configuration?

    ERIC Educational Resources Information Center

    Parish, Thomas S.

    1993-01-01

    College students (n=130) described support system failures they encountered during childhood and adolescence through responses on Personal History Inventory and ratings of self and family on Personal Attribute Inventory. Found significant direct relationships between level of support system failures and negativeness expressed in ratings of both…

  8. Effects of strain rate and confining pressure on the deformation and failure of shale

    SciTech Connect

    Cook, J.M. ); Sheppard, M.C. ); Houwen, O.H. )

    1991-06-01

    Previous work on shale mechanical properties has focused on the slow deformation rates appropriate to wellbore deformation. Deformation of shale under a drill bit occurs at a very high rate, and the failure properties of the rock under these conditions are crucial in determining bit performance and in extracting lithology and pore-pressure information from drilling parameters. Triaxial tests were performed on two nonswelling shales under a wide range of strain rates and confining and pore pressures. At low strain rates, when fluid is relatively free to move within the shale, shale deformation and failure are governed by effective stress or pressure (i.e., total confining pressure minus pore pressure), as is the case for ordinary rock. If the pore pressure in the shale is high, increasing the strain rate beyond about 0.1%/sec causes large increases in the strength and ductility of the shale. Total pressure begins to influence the strength. At high stain rates, the influence of effective pressure decreases, except when it is very low (i.e., when pore pressure is very high); ductility then rises rapidly. This behavior is opposite that expected in ordinary rocks. This paper briefly discusses the reasons for these phenomena and their impact on wellbore and drilling problems.

  9. A Procedure for Modeling Structural Component/Attachment Failure Using Transient Finite Element Analysis

    NASA Technical Reports Server (NTRS)

    Lovejoy, Andrew E.; Jegley, Dawn C. (Technical Monitor)

    2007-01-01

    Structures often comprise smaller substructures that are connected to each other or attached to the ground by a set of finite connections. Under static loading one or more of these connections may exceed allowable limits and be deemed to fail. Of particular interest is the structural response when a connection is severed (failed) while the structure is under static load. A transient failure analysis procedure was developed by which it is possible to examine the dynamic effects that result from introducing a discrete failure while a structure is under static load. The failure is introduced by replacing a connection load history by a time-dependent load set that removes the connection load at the time of failure. The subsequent transient response is examined to determine the importance of the dynamic effects by comparing the structural response with the appropriate allowables. Additionally, this procedure utilizes a standard finite element transient analysis that is readily available in most commercial software, permitting the study of dynamic failures without the need to purchase software specifically for this purpose. The procedure is developed and explained, demonstrated on a simple cantilever box example, and finally demonstrated on a real-world example, the American Airlines Flight 587 (AA587) vertical tail plane (VTP).

  10. Preliminary Evaluation of Various Training Components on Accuracy of Direct Behavior Ratings

    ERIC Educational Resources Information Center

    Chafouleas, Sandra M.; Kilgus, Stephen P.; Riley-Tillman, T. Chris; Jaffery, Rose; Harrison, Sayward

    2012-01-01

    This study examined the impact of various components of rater training on the accuracy of rating behavior using Direct Behavior Rating-Single Item Scales (DBR-SIS). Specifically, the addition of frame-of-reference and rater error training components to a standard package involving an overview and then modeling, practice, and feedback was…

  11. Failure behavior of generic metallic and composite aircraft structural components under crash loads

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.; Robinson, Martha P.

    1990-01-01

    Failure behavior results are presented from crash dynamics research using concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs incorporating improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures including individual fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models.

  12. Detecting application-level failures in component-based internet services.

    PubMed

    Kiciman, Emre; Fox, Armando

    2005-09-01

    Most Internet services (e-commerce, search engines, etc.) suffer faults. Quickly detecting these faults can be the largest bottleneck in improving availability of the system. We present Pinpoint, a methodology for automating fault detection in Internet services by: 1) observing low-level internal structural behaviors of the service; 2) modeling the majority behavior of the system as correct; and 3) detecting anomalies in these behaviors as possible symptoms of failures. Without requiring any a priori application-specific information, Pinpoint correctly detected 89%-96% of major failures in our experiments, as compared with 20%-70% detected by current application-generic techniques.

  13. 12 CFR Appendix A to Subpart A of... - Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 10 2014-01-01 2014-01-01 false Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF FEDERAL HOUSING ENTERPRISE OVERSIGHT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT SAFETY AND SOUNDNESS CAPITAL Minimum Capital Pt. 1750, Subpt. A,...

  14. 12 CFR Appendix A to Subpart A of... - Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 7 2011-01-01 2011-01-01 false Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF FEDERAL HOUSING ENTERPRISE OVERSIGHT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT SAFETY AND SOUNDNESS CAPITAL Minimum Capital Pt. 1750, Subpt. A,...

  15. 12 CFR Appendix A to Subpart A of... - Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 9 2013-01-01 2013-01-01 false Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF FEDERAL HOUSING ENTERPRISE OVERSIGHT, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT SAFETY AND SOUNDNESS CAPITAL Minimum Capital Pt. 1750, Subpt. A,...

  16. Rating Scale Items: A Brief Review of Nomenclature, Components, and Formatting to Inform the Development of Direct Behavior Rating (DBR)

    ERIC Educational Resources Information Center

    Christ, Theodore J.; Boice, Christina

    2009-01-01

    Ratings scales are a common component of many multisource, multimethod frameworks for socioemotional and behavior assessment of children. There is a modest literature base to support the use of attitudinal, behavioral, and personality rating scales. Much of that historic literature focuses on the characteristics and interpretations of specific…

  17. Rating Scale Items: A Brief Review of Nomenclature, Components, and Formatting to Inform the Development of Direct Behavior Rating (DBR)

    ERIC Educational Resources Information Center

    Christ, Theodore J.; Boice, Christina

    2009-01-01

    Ratings scales are a common component of many multisource, multimethod frameworks for socioemotional and behavior assessment of children. There is a modest literature base to support the use of attitudinal, behavioral, and personality rating scales. Much of that historic literature focuses on the characteristics and interpretations of specific…

  18. Poor self-rated health predicts mortality in patients with stable chronic heart failure.

    PubMed

    Inkrot, Simone; Lainscak, Mitja; Edelmann, Frank; Loncar, Goran; Stankovic, Ivan; Celic, Vera; Apostolovic, Svetlana; Tahirovic, Elvis; Trippel, Tobias; Herrmann-Lingen, Christoph; Gelbrich, Götz; Düngen, Hans-Dirk

    2016-12-01

    In heart failure, a holistic approach incorporating the patient's perspective is vital for prognosis and treatment. Self-rated health has strong associations with adverse events and short-term mortality risk, but long-term data are limited. We investigated the predictive value of two consecutive self-rated health assessments with regard to long-term mortality in a large, well characterised sample of elderly patients with stable chronic heart failure. We measured self-rated health by asking 'In general, would you say your health is: 1, excellent; 2, very good; 3, good; 4, fair; 5, poor?' twice: at baseline and the end of a 12-week beta-blocker up-titration period in the CIBIS-ELD trial. Mortality was assessed in an observational follow-up after 2-4 years. A total of 720 patients (mean left ventricular ejection fraction 45±12%, mean age 73±5 years, 36% women) rated their health at both time points. During long-term follow-up, 144 patients died (all-cause mortality 20%). Fair/poor self-rated health in at least one of the two reports was associated with increased mortality (hazard ratio 1.42 per level; 95% confidence interval 1.16-1.75; P<0.001). It remained independently significant in multiple Cox regression analysis, adjusted for N-terminal pro B-type natriuretic peptide (NTproBNP), heart rate and other risk prediction covariates. Self-rated health by one level worse was as predictive for mortality as a 1.9-fold increase in NTproBNP. Poor self-rated health predicts mortality in our long-term follow-up of patients with stable chronic heart failure, even after adjustment for established risk predictors. We encourage clinicians to capture patient-reported self-rated health routinely as an easy to assess, clinically meaningful measure and pay extra attention when self-rated health is poor. © The European Society of Cardiology 2015.

  19. Helium release rates and ODH calculations from RHIC magnet cooling line failure

    SciTech Connect

    Liaw, C.J.; Than, Y.; Tuozzolo, J.

    2011-03-28

    A catastrophic failure of the magnet cooling lines, similar to the LHC superconducting bus failure incident, could discharge cold helium into the RHIC tunnel and cause an Oxygen Deficiency Hazard (ODH) problem. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the insulating vacuum volumes and discharging via the reliefs into the RHIC tunnel, had been developed. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces are included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Results, including helium discharge rates, helium inventory loss, and the resulting oxygen concentration in the RHIC tunnel area, are reported. Good agreement had been achieved when comparing the simulation results, a RHIC sector depressurization test measurement, and some simple analytical calculations.

  20. A Further Study of Productive Failure in Mathematical Problem Solving: Unpacking the Design Components

    ERIC Educational Resources Information Center

    Kapur, Manu

    2011-01-01

    This paper replicates and extends my earlier work on productive failure in mathematical problem solving (Kapur, doi:10.1007/s11251-009-9093-x, 2009). One hundred and nine, seventh-grade mathematics students taught by the same teacher from a Singapore school experienced one of three learning designs: (a) traditional lecture and practice (LP), (b)…

  1. Ambulatory heart rate range predicts mode-specific mortality and hospitalisation in chronic heart failure.

    PubMed

    Cubbon, Richard M; Ruff, Naomi; Groves, David; Eleuteri, Antonio; Denby, Christine; Kearney, Lorraine; Ali, Noman; Walker, Andrew M N; Jamil, Haqeel; Gierula, John; Gale, Chris P; Batin, Phillip D; Nolan, James; Shah, Ajay M; Fox, Keith A A; Sapsford, Robert J; Witte, Klaus K; Kearney, Mark T

    2016-02-01

    We aimed to define the prognostic value of the heart rate range during a 24 h period in patients with chronic heart failure (CHF). Prospective observational cohort study of 791 patients with CHF associated with left ventricular systolic dysfunction. Mode-specific mortality and hospitalisation were linked with ambulatory heart rate range (AHRR; calculated as maximum minus minimum heart rate using 24 h Holter monitor data, including paced and non-sinus complexes) in univariate and multivariate analyses. Findings were then corroborated in a validation cohort of 408 patients with CHF with preserved or reduced left ventricular ejection fraction. After a mean 4.1 years of follow-up, increasing AHRR was associated with reduced risk of all-cause, sudden, non-cardiovascular and progressive heart failure death in univariate analyses. After accounting for characteristics that differed between groups above and below median AHRR using multivariate analysis, AHRR remained strongly associated with all-cause mortality (HR 0.991/bpm increase in AHRR (95% CI 0.999 to 0.982); p=0.046). AHRR was not associated with the risk of any non-elective hospitalisation, but was associated with heart-failure-related hospitalisation. AHRR was modestly associated with the SD of normal-to-normal beats (R(2)=0.2; p<0.001) and with peak exercise-test heart rate (R(2)=0.33; p<0.001). Analysis of the validation cohort revealed AHRR to be associated with all-cause and mode-specific death as described in the derivation cohort. AHRR is a novel and readily available prognosticator in patients with CHF, which may reflect autonomic tone and exercise capacity. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  2. Ambulatory heart rate range predicts mode-specific mortality and hospitalisation in chronic heart failure

    PubMed Central

    Cubbon, Richard M; Ruff, Naomi; Groves, David; Eleuteri, Antonio; Denby, Christine; Kearney, Lorraine; Ali, Noman; Walker, Andrew M N; Jamil, Haqeel; Gierula, John; Gale, Chris P; Batin, Phillip D; Nolan, James; Shah, Ajay M; Fox, Keith A A; Sapsford, Robert J; Witte, Klaus K; Kearney, Mark T

    2016-01-01

    Objective We aimed to define the prognostic value of the heart rate range during a 24 h period in patients with chronic heart failure (CHF). Methods Prospective observational cohort study of 791 patients with CHF associated with left ventricular systolic dysfunction. Mode-specific mortality and hospitalisation were linked with ambulatory heart rate range (AHRR; calculated as maximum minus minimum heart rate using 24 h Holter monitor data, including paced and non-sinus complexes) in univariate and multivariate analyses. Findings were then corroborated in a validation cohort of 408 patients with CHF with preserved or reduced left ventricular ejection fraction. Results After a mean 4.1 years of follow-up, increasing AHRR was associated with reduced risk of all-cause, sudden, non-cardiovascular and progressive heart failure death in univariate analyses. After accounting for characteristics that differed between groups above and below median AHRR using multivariate analysis, AHRR remained strongly associated with all-cause mortality (HR 0.991/bpm increase in AHRR (95% CI 0.999 to 0.982); p=0.046). AHRR was not associated with the risk of any non-elective hospitalisation, but was associated with heart-failure-related hospitalisation. AHRR was modestly associated with the SD of normal-to-normal beats (R2=0.2; p<0.001) and with peak exercise-test heart rate (R2=0.33; p<0.001). Analysis of the validation cohort revealed AHRR to be associated with all-cause and mode-specific death as described in the derivation cohort. Conclusions AHRR is a novel and readily available prognosticator in patients with CHF, which may reflect autonomic tone and exercise capacity. PMID:26674986

  3. A component-level failure detection and identification algorithm based on open-loop and closed-loop state estimators

    NASA Astrophysics Data System (ADS)

    You, Seung-Han; Cho, Young Man; Hahn, Jin-Oh

    2013-04-01

    This study presents a component-level failure detection and identification (FDI) algorithm for a cascade mechanical system subsuming a plant driven by an actuator unit. The novelty of the FDI algorithm presented in this study is that it is able to discriminate failure occurring in the actuator unit, the sensor measuring the output of the actuator unit, and the plant driven by the actuator unit. The proposed FDI algorithm exploits the measurement of the actuator unit output together with its estimates generated by open-loop (OL) and closed-loop (CL) estimators to enable FDI at the component's level. In this study, the OL estimator is designed based on the system identification of the actuator unit. The CL estimator, which is guaranteed to be stable against variations in the plant, is synthesized based on the dynamics of the entire cascade system. The viability of the proposed algorithm is demonstrated using a hardware-in-the-loop simulation (HILS), which shows that it can detect and identify target failures reliably in the presence of plant uncertainties.

  4. Effects of Assuming Independent Component Failure Times, if They Actually Dependent, in a Series System.

    DTIC Science & Technology

    1984-10-26

    or greater, in Figure 2 we plot the ratio - value of A, is assumed known. If X I, X2 are indepen- of the 100 pth upper percentiles under dependence...of 100 pth Percentile Under 0.. UThe mean time to system failure based on (2.1, pendence and Independence Versus Coffelation for assuming independence...Bivariate Lifetables and its Application in Epidemiological Studies of Familial Tendency in Chronic Disease Incidence, Biometrika 65, -’ 141-151. 4. Fisher, L

  5. Unique failure behavior of metal/composite aircraft structural components under crash type loads

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.

    1990-01-01

    Failure behavior results are presented on some of the crash dynamics research conducted with concepts of aircraft elements and substructure which have not necessarily been designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash type loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the thread of similarity in behavior is telling the designer and dynamists a great deal about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures.

  6. Aging behavior, reliability, and failure physics of GaN-based optoelectronic components

    NASA Astrophysics Data System (ADS)

    Zanoni, Enrico; Meneghini, Matteo; Meneghesso, Gaudenzio; De Santi, Carlo; La Grassa, Marco; Buffolo, Matteo; Trivellin, Nicola; Monti, Desiree

    2016-03-01

    This paper critically reviews the most relevant failure modes and mechanisms of InGaN LEDs for lighting application. At chip level, both the epitaxial heterostructure and the ohmic contacts may be affected. This may result in: (i) the formation of defects within the active region, resulting in the increase of non-radiative recombination and leakage current, (ii) the reduction of the injection efficiency consequent to increased trap-assisted tunneling, (iii) the degradation of contact resistance with increase of forward voltage. Package-related failures - not described in this paper - include (iv) thermally-activated degradation processes, affecting the yellow phosphors, the plastic package or the encapsulating materials and (v) darkening of the Ag package reflective coating, the latter due to chemical reaction with contaminants as Cl or S. In order to enucleate and study the different physical failure mechanisms governing device degradation, single quantum well (SQW) blue LEDs, InGaN laser structures and commercially-available white LEDs to high temperature and/or high current density have been submitted to accelerated testing at high temperature and high current density.

  7. A modification of Nissen fundoplication improves patients' outcome and may reduce procedure-related failure rate.

    PubMed

    Bardini, Romeo; Rampado, Sabrina; Salvador, Renato; Zanatta, Lisa; Angriman, Imerio; Degasperi, Silvia; Ganss, Angelica; Savarino, Edoardo

    2017-02-01

    Laparoscopic anti-reflux surgery has a failure rate of 10-20%. We aimed to investigate whether a modification of Nissen fundoplication (MNF) may improve patients' outcome and reduce failure rate. We prospectively compared 40 consecutive patients with gastroesophageal reflux disease who underwent anti-reflux surgery: 20 Nissen fundoplication (NF) and 20 the MNF approach. Eight cases in the MNF group needed redo surgery. The MNF consisted in suturing the esophagus to the diaphragmatic crura on each side by means of 4 non-absorbable stitches and in fixing the upper stitch of the valve to diaphragm. In case of clearly weak crura, a reinforcement with Ultrapro mesh was used. All patients were assessed before and after surgery using validated symptoms and quality of life (GERD-HRQL) questionnaires, manometry and 24-h impedance-pH monitoring, endoscopy and barium-swallow. Mortality and postoperative complications were nil. At a median follow-up of 36 months, no significant differences emerged between the MNF and NF group in terms of symptoms, GERD-HRQL scores, manometric findings, and impedance-pH features. Dysphagia was not reported by the MNF group, while it was quite common (20% vs.0%, p = ns) in the NF group. Anti-reflux surgery was successful in all patients in the MNF group, whereas two patients in the NF group presented a slipped wrap and one recurrent reflux; two of these cases required redo-surgery (10% vs. 0%, p = ns). Our preliminary data demonstrated that the MNF is a safe and effective procedure. Further, it seems to reduce the failure rate associated to the surgical procedure. Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

  8. Simulated Hail Ice Mechanical Properties and Failure Mechanism at Quasi-Static Strain Rates

    NASA Astrophysics Data System (ADS)

    Swift, Jonathan M.

    Hail is a significant threat to aircraft both on the ground and in the air. Aeronautical engineers are interested in better understanding the properties of hail to improve the safety of new aircraft. However, the failure mechanism and mechanical properties of hail, as opposed to clear ice, are not well understood. A literature review identifies basic mechanical properties of ice and a failure mechanism based upon the state of stress within an ice sphere is proposed. To better understand the properties of Simulated Hail Ice (SHI), several tests were conducted using both clear and cotton fiber reinforced ice. Pictures were taken to show the internal crystal structure of SHI. SHI crush tests were conducted to identify the overall force-displacement trends at various quasi-static strain rates. High speed photography was also used to visually track the failure mechanism of spherical SHI. Compression tests were done to measure the compression strength of SHI and results were compared to literature data. Fracture toughness tests were conducted to identify the crack resistance of SHI. Results from testing clear ice samples were successfully compared to previously published literature data to instill confidence in the testing methods. The methods were subsequently used to test and characterize the cotton fiber reinforced ice.

  9. Scheduling Maintenance Operations Which Cause Age-Dependent Failure Rate Changes,

    DTIC Science & Technology

    1983-06-01

    ENGI.. UNCLASSIFIED B EBRAHIMIAN ET AL I JUN 83 F/G 5/1 NLmEEmmEEmmmmEE EEIhEIIhEEIII EEIIIIIIIEIIIE EIIIEIIIIIIIEE IEEIhIhEIhEIhE EIIIEEEEEIhIhE...OPERATIONS WHICH CAUSE AGE-DEPENDENT FAILURE RATE CHANGES BY BEHNAM EBRAHIMIAN AND LEONARD SHAW Prepared for Office of Naval Research Contract N00014-75-C-0858... EBRAHIMIAN AND LEONARD SHAW Prepared for Office of Naval Research Contract N00014-75-C-0858 Report No. POLY EE/CS 83-002 Polytechnic Institute of New York

  10. Predictions and Experimental Microstructural Characterization of High Strain Rate Failure Modes in Layered Aluminum Composites

    NASA Astrophysics Data System (ADS)

    Khanikar, Prasenjit

    Different aluminum alloys can be combined, as composites, for tailored dynamic applications. Most investigations pertaining to metallic alloy layered composites, however, have been based on quasi-static approaches. The dynamic failure of layered metallic composites, therefore, needs to be characterized in terms of strength, toughness, and fracture response. A dislocation-density based crystalline plasticity formulation, finite-element techniques, rational crystallographic orientation relations and a new fracture methodology were used to predict the failure modes associated with the high strain rate behavior of aluminum layered composites. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary (GB) distributions. The new fracture methodology, based on an overlap method and phantom nodes, is used with a fracture criteria specialized for fracture on different cleavage planes. One of the objectives of this investigation, therefore, was to determine the optimal arrangements of the 2139 and 2195 aluminum alloys for a metallic layered composite that would combine strength, toughness and fracture resistance for high strain-rate applications. Different layer arrangements were investigated for high strain-rate applications, and the optimal arrangement was with the high toughness 2139 layer on the bottom, which provided extensive shear strain localization, and the high strength 2195 layer on the top for high strength resistance. The layer thickness of the bottom high toughness layer also affected the bending behavior of the roll-boned interface and the potential delamination of the layers. Shear strain localization, dynamic cracking and delamination were the mutually competing failure mechanisms for the layered metallic composite, and control of these failure modes can be optimized for high strain-rate

  11. Is there a relationship between obesity, heart rate variability and inflammatory parameters in heart failure?

    PubMed

    Taçoy, Gülten; Açikgöz, Kadri; Kocaman, Sinan Altan; Ozdemir, Murat; Cengel, Atiye

    2010-02-01

    To investigate the effect of body mass index (BMI) on heart rate variability (HRV) and inflammatory parameters in patients with heart failure. We analyzed 55 consecutive patients (mean age, 63.5 +/- 12.8 years; male/female, 39/16) with symptomatic left ventricular systolic (ejection fraction <45%) heart failure. The participants were classified into three categories according to BMI: lean (BMI < 25 kg/m2), overweight (BMI = 25-29.9 kg/m2) and obese (BMI >or= 30 kg/m2). The cause of heart failure was mainly ischemic heart disease (75%) with mean ejection fraction 30 +/- 7%. Plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) and C-reactive protein levels were measured, and time-domain HRV indices were determined on Holter electrocardiogram. The relationship between HRV indices and laboratory, inflammatory and echocardiographic parameters was investigated with correlation analysis. Age, sex, clinical characteristics (hypertension, diabetes mellitus, dyslipidemia, family history, smoking) were similar between groups. BMI was inversely correlated with NT-pro BNP levels (P = 0.001). HRV indices did not differ between groups. Correlation analysis demonstrated the relationship between HRV indices and fasting blood glucose (SDNN, SDANN, SDNNI, root mean square successive differences, VTI), C-reactive protein (SDANN, SDNNI, VTI), pulmonary artery pressure (SDNN, SDANN, VTI) levels. In systolic heart failure patients a higher BMI is associated with decreased NT-proBNP levels. Although HRV indices were not different between groups, inflammatory parameters, fasting blood glucose and pulmonary artery pressure were correlated with them.

  12. Estimation of waste component-specific landfill decay rates using laboratory-scale decomposition data.

    PubMed

    De la Cruz, Florentino B; Barlaz, Morton A

    2010-06-15

    The current methane generation model used by the U.S. EPA (Landfill Gas Emissions Model) treats municipal solid waste (MSW) as a homogeneous waste with one decay rate. However, component-specific decay rates are required to evaluate the effects of changes in waste composition on methane generation. Laboratory-scale rate constants, k(lab), for the major biodegradable MSW components were used to derive field-scale decay rates (k(field)) for each waste component using the assumption that the average of the field-scale decay rates for each waste component, weighted by its composition, is equal to the bulk MSW decay rate. For an assumed bulk MSW decay rate of 0.04 yr(-1), k(field) was estimated to be 0.298, 0.171, 0.015, 0.144, 0.033, 0.02, 0.122, and 0.029 yr(-1), for grass, leaves, branches, food waste, newsprint, corrugated containers, coated paper, and office paper, respectively. The effect of landfill waste diversion programs on methane production was explored to illustrate the use of component-specific decay rates. One hundred percent diversion of yard waste and food waste reduced the year 20 methane production rate by 45%. When a landfill gas collection schedule was introduced, collectable methane was most influenced by food waste diversion at years 10 and 20 and paper diversion at year 40.

  13. Association between atrial fibrillatory rate and heart rate variability in patients with atrial fibrillation and congestive heart failure.

    PubMed

    Corino, Valentina D A; Cygankiewicz, Iwona; Mainardi, Luca T; Stridh, Martin; Vasquez, Rafael; Bayes de Luna, Antonio; Holmqvist, Fredrik; Zareba, Wojciech; Platonov, Pyotr G

    2013-01-01

    Even if atrial fibrillatory rate (AFR) has been related to clinical outcome in patients with atrial fibrillation (AF), its relation with ventricular response has not been deeply studied. The aim of this study was to investigate the relation between AFR and RR series variability in patients with AF. Twenty-minute electrocardiograms in orthogonal leads were processed to extract AFR, using spatiotemporal QRST cancellation and time frequency analysis, and RR series in 127 patients (age 69 ± 11 years) with congestive heart failure (NYHA II-III) enrolled in the MUSIC study (MUerte Subita en Insufficiencia Cardiaca). Heart rate variability and irregularity were assessed by time domain parameters and entropy-based indices, respectively and their correlation with AFR investigated. Variability measures seem not to be related to AFR, while irregularity measures do. A significant correlation between AFR and variability parameters of heart rate variability during AF was found only in patients not treated with antiarrhythmics drugs (correlation = 0.56 P < 0.05 for pNN50), while this correlation was lost in patients taking rate- or rhythm-control drugs. A significant positive correlation between AFR and indices of RR irregularity was found, showing that a higher AFR is related to a less organized RR series (correlation = 0.33 P < 0.05 for regularity index for all patients, correlation increased in subgroups of patients treated with the same drug). These results suggest that a higher AFR is associated with a higher degree of irregularity of ventricular response that is observed regardless of the use of rate-controlling drugs. ©2012, Wiley Periodicals, Inc.

  14. Hospital strategies associated with 30-day readmission rates for patients with heart failure.

    PubMed

    Bradley, Elizabeth H; Curry, Leslie; Horwitz, Leora I; Sipsma, Heather; Wang, Yongfei; Walsh, Mary Norine; Goldmann, Don; White, Neal; Piña, Ileana L; Krumholz, Harlan M

    2013-07-01

    Reducing hospital readmission rates is a national priority; however, evidence about hospital strategies that are associated with lower readmission rates is limited. We sought to identify hospital strategies that were associated with lower readmission rates for patients with heart failure. Using data from a Web-based survey of hospitals participating in national quality initiatives to reduce readmission (n=599; 91% response rate) during 2010-2011, we constructed a multivariable linear regression model, weighted by hospital volume, to determine strategies independently associated with risk-standardized 30-day readmission rates (RSRRs) adjusted for hospital teaching status, geographic location, and number of staffed beds. Strategies that were associated with lower hospital RSRRs included the following: (1) partnering with community physicians or physician groups to reduce readmission (0.33% percentage point lower RSRRs; P=0.017), (2) partnering with local hospitals to reduce readmissions (0.34 percentage point; P=0.020), (3) having nurses responsible for medication reconciliation (0.18 percentage point; P=0.002), (4) arranging follow-up appointments before discharge (0.19 percentage point; P=0.037), (5) having a process in place to send all discharge paper or electronic summaries directly to the patient's primary physician (0.21 percentage point; P=0.004), and (6) assigning staff to follow up on test results that return after the patient is discharged (0.26 percentage point; P=0.049). Although statistically significant, the magnitude of the effects was modest with individual strategies associated with less than half a percentage point reduction in RSRRs; however, hospitals that implemented more strategies had significantly lower RSRRs (reduction of 0.34 percentage point for each additional strategy). Several strategies were associated with lower hospital RSRRs for patients with heart failure.

  15. Generating parity relations for detecting and identifying control system component failures

    NASA Technical Reports Server (NTRS)

    Vander Velder, Wallace E.; Massoumnia, Mohammad-Ali

    1988-01-01

    The monitoring of control system sensors and actuators for failures is presently undertaken by means of an exceptionally simple form of generalized parity relations based on a discrete-time model of the dynamics of linear, time-invariant systems. These generalized parity relations are constructed by recourse to a transfer matrix-description of the system that is additionally useful in the interpretation of their properties. Attention is given to a novel method for constructing the parity relation of minimum length that depends on the output of only a single sensor.

  16. Post-Exercise Heart Rate Recovery Independently Predicts Mortality Risk in Patients with Chronic Heart Failure

    PubMed Central

    Tang, Yi-Da; Dewland, Thomas A.; Wencker, Detlef; Katz, Stuart D.

    2009-01-01

    Background Post-exercise heart rate recovery (HRR) is an index of parasympathetic function associated with clinical outcomes in populations with and without documented coronary heart disease. Decreased parasympathetic activity is thought to be associated with disease progression in chronic heart failure (HF), but an independent association between post-exercise HRR and clinical outcomes among such patients has not been established. Methods and Results We measured HRR (calculated as the difference between heart rate at peak exercise and after 1 minute of recovery) in 202 HF subjects and recorded 17 mortality and 15 urgent transplantation outcome events over 624 days of follow-up. Reduced post-exercise HRR was independently associated with increased event risk after adjusting for other exercise-derived variables (peak oxygen uptake and VE/VCO2 slope), for the Heart Failure Survival Score (adjusted HR 1.09 for one beat/min reduction, 95% CI 1.05-1.13, p<0.0001) and the Seattle Heart Failure Model score (adjusted HR 1.08 for one beat/min reduction, 95% CI 1.05-1.12, p<0.0001). Subjects in the lowest risk tertile based on post-exercise HRR (≥30 beats/min) had low risk of events irrespective of the risk predicted by the survival scores. In a subgroup of 15 subjects, reduced post-exercise HRR was associated with increased serum markers of inflammation (interleukin-6 r=0.58, p=0.024, high sensitivity C-reactive protein r=0.66, p=0.007). Conclusions Post-exercise HRR predicts mortality risk in patients with HF and provides prognostic information independent of previously described survival models. Pathophysiologic links between autonomic function and inflammation may be mediators of this association. PMID:19944361

  17. Post-exercise heart rate recovery independently predicts mortality risk in patients with chronic heart failure.

    PubMed

    Tang, Yi-Da; Dewland, Thomas A; Wencker, Detlef; Katz, Stuart D

    2009-12-01

    Post-exercise heart rate recovery (HRR) is an index of parasympathetic function associated with clinical outcomes in populations with and without documented coronary heart disease. Decreased parasympathetic activity is thought to be associated with disease progression in chronic heart failure (HF), but an independent association between post-exercise HRR and clinical outcomes among such patients has not been established. We measured HRR (calculated as the difference between heart rate at peak exercise and after 1 minute of recovery) in 202 HF subjects and recorded 17 mortality and 15 urgent transplantation outcome events over 624 days of follow-up. Reduced post-exercise HRR was independently associated with increased event risk after adjusting for other exercise-derived variables (peak oxygen uptake and change in minute ventilation per change in carbon dioxide production slope), for the Heart Failure Survival Score (adjusted HR 1.09 for 1 beat/min reduction, 95% CI 1.05-1.13, P < .0001), and the Seattle Heart Failure Model score (adjusted HR 1.08 for one beat/min reduction, 95% CI 1.05-1.12, P < .0001). Subjects in the lowest risk tertile based on post-exercise HRR (>or=30 beats/min) had low risk of events irrespective of the risk predicted by the survival scores. In a subgroup of 15 subjects, reduced post-exercise HRR was associated with increased serum markers of inflammation (interleukin-6, r = 0.58, P = .024; high-sensitivity C-reactive protein, r = 0.66, P = .007). Post-exercise HRR predicts mortality risk in patients with HF and provides prognostic information independent of previously described survival models. Pathophysiologic links between autonomic function and inflammation may be mediators of this association.

  18. Chemical components separation with botulinum toxin A: a novel technique to improve primary fascial closure rates of the open abdomen.

    PubMed

    Zielinski, M D; Goussous, N; Schiller, H J; Jenkins, D

    2013-02-01

    Failure to definitively close the open abdomen (OA) after damage control laparotomy leads to considerable morbidity and mortality. We have developed a novel technique, the "chemical components separation," which incorporates injection of botulinum toxin A (BTX), a long-term flaccid paralytic, into the lateral abdominal wall musculature. This is a retrospective review of all OA patients (age ≥18) from December 2009-June 2010 who underwent BTX injection. Under ultrasound guidance, a total of 300 units of BTX were injected into the external oblique, internal oblique and transversus abdominus. A total of 18 patients were injected with a median age of 66 years (56 % male). Indications for OA treatment included questionable bowel viability (39 %), shock (33 %), loss of abdominal domain (6 %) and feculent contamination (17 %). Median ASA score was 3 with an APACHE 3 score of 85. Patients underwent a median of 4 serial abdominal explorations. The primary fascial closure rate was 83 % with a partial fascial closure rate of 6 % and planned ventral hernia rate of 11 %. Of the 9 patients injected within 24 h of their initial OA procedure, 89 % achieved primary fascial closure. Mortality was 11 %; death was unrelated to BTX injection. The overall complication rate was 67 %; specific complications rates included fascial dehiscence (11 %), enterocutaneous fistula development (0 %), intra-abdominal abscess (44 %) and deep surgical site infection (33 %). The "chemical components separation" technique described is safe and avoids the extensive dissection necessary for mechanical components separation in critically ill patients with infected/contaminated abdominal domains. While further evaluation is required, the described technique provides potential to improve delayed primary fascial closure rates in the OA setting.

  19. Mesenchymal Stem Cells Improve Heart Rate Variability and Baroreflex Sensitivity in Rats with Chronic Heart Failure

    PubMed Central

    de Morais, Sharon Del Bem Velloso; da Silva, Luiz Eduardo Virgilio; Lataro, Renata Maria; Silva, Carlos Alberto Aguiar; de Oliveira, Luciano Fonseca Lemos; de Carvalho, Eduardo Elias Vieira; Simões, Marcus Vinicius; da Silva Meirelles, Lindolfo; Fazan, Rubens

    2015-01-01

    Heart failure induced by myocardial infarct (MI) attenuates the heart rate variability (HRV) and baroreflex sensitivity, which are important risk factors for life-threatening cardiovascular events. Therapies with mesenchymal stem cells (MSCs) have shown promising results after MI. However, the effects of MSCs on hemodynamic (heart rate and arterial pressure) variability and baroreflex sensitivity in chronic heart failure (CHF) following MI have not been evaluated thus far. Male Wistar rats received MSCs or saline solution intravenously 1 week after ligation of the left coronary artery. Control (noninfarcted) rats were also evaluated. MI size was assessed using single-photon emission computed tomography (SPECT). The left ventricular ejection fraction (LVEF) was evaluated using radionuclide ventriculography. Four weeks after MSC injection, the animals were anesthetized and instrumented for chronic ECG recording and catheters were implanted in the femoral artery to record arterial pressure. Arterial pressure and HRVs were determined in time and frequency domain (spectral analysis) while HRV was also examined using nonlinear methods: DFA (detrended fluctuation analysis) and sample entropy. The initial MI size was the same among all infarcted rats but was reduced by MSCs. CHF rats exhibited increased myocardial interstitial collagen and sample entropy combined with the attenuation of the following cardiocirculatory parameters: DFA indices, LVEF, baroreflex sensitivity, and HRV. Nevertheless, MSCs hampered all these alterations, except the LVEF reduction. Therefore, 4 weeks after MSC therapy was applied to CHF rats, MI size and myocardial interstitial fibrosis decreased, while baroreflex sensitivity and HRV improved. PMID:26059001

  20. Failure Rates and Patterns of Recurrence in Patients With Resected N1 Non-Small-Cell Lung Cancer

    SciTech Connect

    Varlotto, John M.; Medford-Davis, Laura Nyshel; Recht, Abram; Flickinger, John C.; Schaefer, Eric; DeCamp, Malcolm M.

    2011-10-01

    Purpose: To examine the local and distant recurrence rates and patterns of failure in patients undergoing potentially curative resection of N1 non-small-cell lung cancer. Methods and Materials: The study included 60 consecutive unirradiated patients treated from 2000 to 2006. Median follow-up was 30 months. Failure rates were calculated by the Kaplan-Meier method. A univariate Cox proportional hazard model was used to assess factors associated with recurrence. Results: Local and distant failure rates (as the first site of failure) at 2, 3, and 5 years were 33%, 33%, and 46%; and 26%, 26%, and 32%, respectively. The most common site of local failure was in the mediastinum; 12 of 18 local recurrences would have been included within proposed postoperative radiotherapy fields. Patients who received chemotherapy were found to be at increased risk of local failure, whereas those who underwent pneumonectomy or who had more positive nodes had significantly increased risks of distant failure. Conclusions: Patients with resected non-small-cell lung cancer who have N1 disease are at substantial risk of local recurrence as the first site of relapse, which is greater than the risk of distant failure. The role of postoperative radiotherapy in such patients should be revisited in the era of adjuvant chemotherapy.

  1. SU-E-T-495: Neutron Induced Electronics Failure Rate Analysis for a Single Room Proton Accelerator

    SciTech Connect

    Knutson, N; DeWees, T; Klein, E

    2014-06-01

    Purpose: To determine the failure rate as a function of neutron dose of the range modulator's servo motor controller system (SMCS) while shielded with Borated Polyethylene (BPE) and unshielded in a single room proton accelerator. Methods: Two experimental setups were constructed using two servo motor controllers and two motors. Each SMCS was then placed 30 cm from the end of the plugged proton accelerator applicator. The motor was then turned on and observed from outside of the vault while being irradiated to known neutron doses determined from bubble detector measurements. Anytime the motor deviated from the programmed motion a failure was recorded along with the delivered dose. The experiment was repeated using 9 cm of BPE shielding surrounding the SMCS. Results: Ten SMCS failures were recorded in each experiment. The dose per monitor unit for the unshielded SMCS was 0.0211 mSv/MU and 0.0144 mSv/MU for the shielded SMCS. The mean dose to produce a failure for the unshielded SMCS was 63.5 ± 58.3 mSv versus 17.0 ±12.2 mSv for the shielded. The mean number of MUs between failures were 2297 ± 1891 MU for the unshielded SMCS and 2122 ± 1523 MU for the shielded. A Wilcoxon Signed Ranked test showed the dose between failures were significantly different (P value = 0.044) while the number of MUs between failures were not (P value = 1.000). Statistical analysis determined a SMCS neutron dose of 5.3 mSv produces a 5% chance of failure. Depending on the workload and location of the SMCS, this failure rate could impede clinical workflow. Conclusion: BPE shielding was shown to not reduce the average failure of the SMCS and relocation of the system outside of the accelerator vault was required to lower the failure rate enough to avoid impeding clinical work flow.

  2. Increasing body mass index predicts increasing difficulty, failure rate, and time to discovery of failure of epidural anesthesia in laboring patients.

    PubMed

    Kula, Ayse O; Riess, Matthias L; Ellinas, Elizabeth H

    2017-02-01

    Obese parturients both greatly benefit from neuraxial techniques, and may represent a technical challenge to obstetric anesthesiologists. Several studies address the topic of obesity and neuraxial analgesia in general, but few offer well described definitions or rates of "difficulty" and "failure" of labor epidural analgesia. Providing those definitions, we hypothesized that increasing body mass index (BMI) is associated with negative outcomes in both categories and increased time needed for epidural placement. Single center retrospective chart review. Labor and Delivery Unit of an inner city academic teaching hospital. 2485 parturients, ASA status 2 to 4, receiving labor epidural analgesia for anticipated vaginal delivery. None. We reviewed quality assurance and anesthesia records over a 12-month period. "Failure" was defined as either inadequate analgesia or a positive test dose, requiring replacement, and/or when the anesthesia record stated they failed. "Difficulty" was defined as six or more needle redirections or a note indicating difficulty in the anesthesia record. Overall epidural failure and difficulty rates were 4.3% and 3.0%, respectively. Patients with a BMI of 30kg/m(2) or higher had a higher chance of both failure and difficulty with two and almost three fold increases, respectively. Regression analysis indicated that failure was best predicted by BMI and less provider training while difficulty was best predicted by BMI. Additionally, increased BMI was associated with increased time of discovery of epidural catheter failure. Obesity is associated with increasing technical difficulty and failure of neuraxial analgesia for labor. Practitioners should consider allotting extra time for obese parturients in order to manage potential problems. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Systematic Characterization of Component Failures for the DIII-D Tokamak

    SciTech Connect

    Petersen, P.I.

    1999-08-01

    A fusion reactor will be a fairly complex system consisting of many components. All the components are required to work in order to produce a plasma and control it. Some of the components will be large, and for economic reasons there will not be spares for all components. It is therefore important to have a system whereby troubles are communicated, recorded and analyzed. Such a trouble report system has been in place at the DIII-D tokamak facility for many years. The purpose of the system is to easily facilitate communication between the people that discover problems and those that fix the problems. The trouble sheets are logged into a computer database that is used to characterize the kind of problems that the facility experiences, and determine which equipment, software, or human errors are causing significant downtime. The information is also used to evaluate whether sufficient maintenance is done to the equipment and to provide a basis for replacing it. The original system was based on paper forms. About a year ago the system was changed to a web-based system. In the new system a trouble report is filled out using a web browser, and the information is emailed to the repair personnel and managers as soon as the form is submitted through the web. The paper will discuss the problems experienced at the DIII-D facility, and how the information is used to adjust the preventive maintenance schedule.

  4. A mesoscopic reaction rate model for shock initiation of multi-component PBX explosives.

    PubMed

    Liu, Y R; Duan, Z P; Zhang, Z Y; Ou, Z C; Huang, F L

    2016-11-05

    The primary goal of this research is to develop a three-term mesoscopic reaction rate model that consists of a hot-spot ignition, a low-pressure slow burning and a high-pressure fast reaction terms for shock initiation of multi-component Plastic Bonded Explosives (PBX). Thereinto, based on the DZK hot-spot model for a single-component PBX explosive, the hot-spot ignition term as well as its reaction rate is obtained through a "mixing rule" of the explosive components; new expressions for both the low-pressure slow burning term and the high-pressure fast reaction term are also obtained by establishing the relationships between the reaction rate of the multi-component PBX explosive and that of its explosive components, based on the low-pressure slow burning term and the high-pressure fast reaction term of a mesoscopic reaction rate model. Furthermore, for verification, the new reaction rate model is incorporated into the DYNA2D code to simulate numerically the shock initiation process of the PBXC03 and the PBXC10 multi-component PBX explosives, and the numerical results of the pressure histories at different Lagrange locations in explosive are found to be in good agreements with previous experimental data.

  5. Heart rate turbulence predicts all-cause mortality and sudden death in congestive heart failure patients.

    PubMed

    Cygankiewicz, Iwona; Zareba, Wojciech; Vazquez, Rafael; Vallverdu, Montserrat; Gonzalez-Juanatey, Jose R; Valdes, Mariano; Almendral, Jesus; Cinca, Juan; Caminal, Pere; de Luna, Antoni Bayes

    2008-08-01

    Abnormal heart rate turbulence (HRT) has been documented as a strong predictor of total mortality and sudden death in postinfarction patients, but data in patients with congestive heart failure (CHF) are limited. The aim of this study was to evaluate the prognostic significance of HRT for predicting mortality in CHF patients in New York Heart Association (NYHA) class II-III. In 651 CHF patients with sinus rhythm enrolled into the MUSIC (Muerte Subita en Insuficiencia Cardiaca) study, the standard HRT parameters turbulence onset (TO) and slope (TS), as well as HRT categories, were assessed for predicting total mortality and sudden death. HRT was analyzable in 607 patients, mean age 63 years (434 male), 50% of ischemic etiology. During a median follow up of 44 months, 129 patients died, 52 from sudden death. Abnormal TS and HRT category 2 (HRT2) were independently associated with increased all-cause mortality (HR: 2.10, CI: 1.41 to 3.12, P <.001 and HR: 2.52, CI: 1.56 to 4.05, P <.001; respectively), sudden death (HR: 2.25, CI: 1.13 to 4.46, P = .021 for HRT2), and death due to heart failure progression (HR: 4.11, CI: 1.84 to 9.19, P <.001 for HRT2) after adjustment for clinical covariates in multivariate analysis. The prognostic value of TS for predicting total mortality was similar in various groups dichotomized by age, gender, NYHA class, left ventricular ejection fraction, and CHF etiology. TS was found to be predictive for total mortality only in patients with QRS > 120 ms. HRT is a potent risk predictor for both heart failure and arrhythmic death in patients with class II and III CHF.

  6. Heart rate reduction with ivabradine in patients with acute decompensated systolic heart failure.

    PubMed

    Sargento, Luis; Satendra, Milan; Longo, Susana; Lousada, Nuno; dos Reis, Roberto Palma

    2014-06-01

    In patients with acute decompensated systolic heart failure (ADSHF) high resting heart rate (HR) could be either a compensatory mechanism or contribute to worsening heart failure. The aim of this study was to evaluate, in patients with ADSHF and resting HR >70 bpm, the early (within 24 h) and late (at discharge) effects of oral administration of ivabradine on HR reduction. Ten consecutive patients with ADSHF, left ventricular ejection fraction <40 % and HR >70 bpm, without other acute conditions or inotropic therapy, began open-label treatment with oral ivabradine according to a pre-established Heart Failure Unit protocol. We obtained clinical and laboratory data at four periods: admission (T0), immediately before initiation of ivabradine (T2), 24 h after initiation of ivabradine (T3), and at discharge (T4). Ivabradine was administered in 60 % of the patients before the second day. HR decreased 10.7 ± 7.2 bpm at T3 (p < 0.001) and 16.3 ± 8.2 bpm at T4 (p = 0.002). The systolic blood pressure decreased at T3 (p = 0.012), returning to baseline values at T4. There was no change in diastolic and mean blood pressure. New York Heart Association (NYHA) class improvement by two levels was associated with lower HR at T4 (p = 0.033). HR and N-terminal pro-brain natriuretic peptide (Nt-ProBNP) at baseline correlated significantly [Spearman correlation coefficient (rs) = 0.789, p = 0.013]. Total Nt-ProBNP reduction correlated with the HR before (r = 0.762, p = 0.028) and after (T3: r = 0.647, p = 0.083; T4: r = 0.738, p = 0.037) ivabradine addition. In the present cohort of patients with ADSHF and HR >70 bpm, the selective reduction of HR with oral ivabradine was safe and efficient.

  7. Skeletal muscle electrical stimulation improves baroreflex sensitivity and heart rate variability in heart failure rats.

    PubMed

    Lazzarotto Rucatti, Ananda; Jaenisch, Rodrigo Boemo; Rossato, Douglas Dalcin; Bonetto, Jéssica Hellen Poletto; Ferreira, Janaína; Xavier, Leder Leal; Sonza, Anelise; Dal Lago, Pedro

    2015-12-01

    The goal of the current study was to evaluate the effects of electrical stimulation (ES) on the arterial baroreflex sensitivity (BRS) and cardiovascular autonomic control in rats with chronic heart failure (CHF). Male Wistar rats were designated to one of four groups: placebo sham (P-Sham, n=9), ES sham (ES-Sham, n=9), placebo CHF (P-CHF, n=9) or ES CHF (ES-CHF, n=9). The ES was adjusted at a low frequency (30 Hz), duration of 250 μs, with hold and rest time of 8s (4 weeks, 30 min/day, 5 times/week). It was applied on the gastrocnemius muscle with intensity to produce a visible muscle contraction. The rats assigned to the placebo groups performed the same procedures with the equipment turned off. The two-way ANOVA and the post hoc Student-Newman-Keuls tests (P<0.05) were used to data comparison. The BRS was higher in ES-Sham group compared to the P-Sham group and the ES-CHF group compared to the P-CHF group. ES was able to decrease heart rate sympatho-vagal modulation and peripheral sympathetic modulation in ES-CHF compared to P-CHF group. Interestingly, heart rate sympatho-vagal modulation was similar between ES-CHF and P-Sham groups. Thus, ES enhances heart rate parasympathetic modulation on heart failure (ES-CHF) compared to placebo (P-CHF), with consequent decrease of sympatho-vagal balance in the ES-CHF group compared to the P-CHF. The results show that a 4 week ES protocol in CHF rats enhances arterial BRS and cardiovascular autonomic control.

  8. Strain rate and anisotropy effects on the tensile failure characteristics of human skin.

    PubMed

    Ottenio, Mélanie; Tran, Doris; Ní Annaidh, Aisling; Gilchrist, Michael D; Bruyère, Karine

    2015-01-01

    The anisotropic failure characteristics of human skin are relatively unknown at strain rates typical in impact biomechanics. This study reports the results of an experimental protocol to quantify the effect of dynamic strain rates and the effect of sample orientation with respect to the Langer lines. Uniaxial tensile tests were carried out at three strain rates (0.06s(-1), 53s(-1), and 167s(-1)) on 33 test samples excised from the back of a fresh cadaver. The mean ultimate tensile stress, mean elastic modulus and mean strain energy increased with increasing strain rates. While the stretch ratio at ultimate tensile stress was not affected by the strain rate, it was influenced by the orientation of the samples (parallel and perpendicular to the Langer lines. The orientation of the sample also had a strong influence on the ultimate tensile stress, with a mean value of 28.0 ± 5.7 MPa for parallel samples, and 15.6 ± 5.2 MPa for perpendicular samples, and on the elastic modulus, with corresponding mean values of 160.8 MPa ± 53.2 MPa and 70.6 MPa ± 59.5 MPa. The study also pointed out the difficulties in controlling the effective applied strain rate in dynamic characterization of soft tissue and the resulting abnormal stress-strain relationships. Finally, data collected in this study can be used to develop constitutive models where high loading rates are of primary interest. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. [Scientific Evaluation of TCM Clinical Outcomes Rating Scale for Heart Failure Based on Patients Report].

    PubMed

    Zhao, Zhi-qiang; Mao, Jing-yuan; Wang, Xian-liang; Hou, Ya-zhu; Bi, Ying-fei

    2016-03-01

    To evaluate the reliability, validity, and responsiveness of traditional Chinese medicine (TCM) clinical outcomes rating scale for heart failure (HF) based on patients' report. TCM clinical outcomes rating scale for HF (TCM-HF-PRO) were evaluated based on 340 HF patients' report from multiple centers. The completion of the investigation was recorded. Cronbach's α coefficient and split-half reliability were used for reliability analysis, and factor analysis was used to assess the construct validity of the rating scale. Pearson correlation analysis was then used for criterion validity analysis. Discriminant analysis was used to assess the responsiveness of the scale. All 340 HF patients having complete TCM-HF-PRO data were assigned to the treatment group and the control group by central randomization. The total TCM-HF-PRO scores of the two groups were compared using paired t-test to reflect the longitude responsiveness of the scale before treatment and at week 2 after treatment. (1) The recycling rate of the scale was 100.0%. One of them was not filled completely, which was rejected thereby. So the completion rate was 99.7%. The completion time for TCM-HF-PRO scale ranged 15 to 25 min. (2) The Cronbach's α coefficient of rating scale was 0.903, split-half reliability was 0.844 and 0.849. (3) Confirmatory factor analysis showed that 7 factors and items formed according to maximum load factor basically coincided with the construct of the rating scale, 7 factors accumulated contribution rate was 43.8%. TCM clinical outcomes rating scale for HF based on patients' report was relatively better correlated with the Minnesota living with HF questionnaire (r = 0.726, P < 0.01). (4) Discriminant analysis showed that the rating scale correctly classified more than 78.8% of case studies having confirmed initial differential diagnosis by experts. The total scale of the rating scale decreased more in the two group after treatment, with significant difference as compared with

  10. Optimization of pharmacotherapy in chronic heart failure: is heart rate adequately addressed?

    PubMed

    Franke, Jennifer; Wolter, Jan Sebastian; Meme, Lillian; Keppler, Jeannette; Tschierschke, Ramon; Katus, Hugo A; Zugck, Christian

    2013-01-01

    The aim of the study is to evaluate the use of beta-blockers in chronic heart failure (CHF) and the extent of heart rate reduction achieved in clinical practice and to determine differences in outcome of patients who fulfilled select inclusion criteria of the SHIFT study according to resting heart rate modulated by beta-blocker therapy. We evaluated an all-comer population of our dedicated CHF outpatient clinic between 2006 and 2010. For inclusion, individually optimized doses of guideline-recommended pharmacotherapy including beta-blockers had to be maintained for at least 3 months and routine follow-up performed at our outpatient CHF-clinic thereafter. Treatment dosages of beta-blockers, and demographic and clinical profiles including resting heart rate were assessed. The outcome of patients who fulfilled select inclusion criteria of the SHIFT study (left-ventricular ejection fraction (LVEF) ≤35 %, sinus rhythm, NYHA II-IV) and were followed-up for at least 1 year was stratified according to resting heart rates: ≥75 versus <75 bpm and ≥70 versus <70 bpm. The composite primary endpoint was defined as all-cause death or hospital admission for worsening heart failure during 12-month follow-up. In total, 3,181 patients were assessed in regard to treatment dosages of beta-blockers, and demographic and clinical profiles including resting heart rate. Of the overall studied population, 443 patients fulfilled all inclusion criteria and entered outcome analysis. Median observation time of survivors was 27.5 months with 1,039.7 observation-years in total. Up-titration to at least half the evidence-based target dose of beta-blockers was achieved in 69 % and full up-titration in 29 % of these patients. Patients with increased heart rates were younger, more often male, exhibited a higher NYHA functional class and lower LVEF. The primary endpoint occurred in 21 % of patients in the ≥70 bpm group versus 9 % of patients in the group with heart rates <70

  11. Failure of Ductile Materials and Components at High Rates of Loading

    DTIC Science & Technology

    2005-09-16

    a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM- YYYY) 2. REPORT TYPE 3. DATES...theoretical effort in understanding the localization of plastic defor- mation has been based on Hill’s general theory of bifurcation. A summary of this... theory has been given by Hill (Muskhelishvili Anniversary Volume 1961). Hill and Hutchinson (Journal of the Mechanics and Physics of Solids 1975) have

  12. Potential radiological exposure rates resulting from hypothetical dome failure at Tank W-10

    SciTech Connect

    Not Available

    1994-07-01

    The main plant area at Oak Ridge National Laboratory (ORNL) contains 12 buried Gunite tanks that were used for the storage and transfer of liquid radioactive waste. Although the tanks are no longer in use, they are known to contain some residual contaminated sludges and liquids. In the event of an accidental tank dome failure, however unlikely, the liquids, sludges, and radioactive contaminants within the tank walls themselves could create radiation fields and result in above-background exposures to workers nearby. This Technical Memorandum documents a series of calculations to estimate potential radiological exposure rates and total exposures to workers in the event of a hypothetical collapse of a Gunite tank dome. Calculations were performed specifically for tank W-10 because it contains the largest radioactivity inventory (approximately half of the total activity) of all the Gunite tanks. These calculations focus only on external, direct gamma exposures for prescribed, hypothetical exposure scenarios and do not address other possible tank failure modes or routes of exposure. The calculations were performed with established, point-kernel gamma ray modeling codes.

  13. Exercise stroke volume and heart rate response differ in right and left heart failure.

    PubMed

    Groepenhoff, Herman; Westerhof, Nico; Jacobs, Wouter; Boonstra, Anco; Postmus, Piet E; Vonk-Noordegraaf, Anton

    2010-07-01

    In pulmonary arterial hypertension (PAH), the exercise-induced increase in stroke volume (SV) is limited by the increase in pulmonary artery pressure. In left heart failure (LHF), systemic arterial pressure increases little during exercise, and the SV increase is limited by the left ventricle itself. These differences might be reflected by a dissimilar SV and heart rate (HR) response to exercise, which could have important therapeutic implications, for example in beta-blocker therapy. Therefore, we tested the hypothesis that SV and HR responses during exercise are different between PAH and LHF patients. We included 28 PAH and 18 LHF patients (recruited from the heart failure unit) matched on a maximal oxygen uptake of <15 mL/kg/min, who were referred to our Pulmonary Function Department between 2000 and 2008 for a maximal cardio-pulmonary exercise test. Only patients who had not been exposed to beta-blockers were included. Pulmonary arterial hypertension and LHF patient groups had equally impaired exercise tolerance (about 42% of predicted) with a maximal oxygen uptake of 0.80 +/- 0.29 and 0.86 +/- 0.19 L/min. The peak SV response to exercise was significantly lower in PAH patients (-14 mL, P = 0.01); this was compensated by a steeper slope of HR relating to oxygen uptake (0.03 beats/mL, P = 0.001). We conclude that PAH patients have a smaller SV response, but a larger HR response than LHF patients.

  14. Rate-dependent activation failure in isolated cardiac cells and tissue due to Na+ channel block

    PubMed Central

    Spindler, Anthony J.; Paterson, David; Noble, Denis

    2015-01-01

    While it is well established that class-I antiarrhythmics block cardiac sodium channels, the mechanism of action of therapeutic levels of these drugs is not well understood. Using a combination of mathematical modeling and in vitro experiments, we studied the failure of activation of action potentials in single ventricular cells and in tissue caused by Na+ channel block. Our computations of block and unblock of sodium channels by a theoretical class-Ib antiarrhythmic agent predict differences in the concentrations required to cause activation failure in single cells as opposed to multicellular preparations. We tested and confirmed these in silico predictions with in vitro experiments on isolated guinea-pig ventricular cells and papillary muscles stimulated at various rates (2–6.67 Hz) and exposed to various concentrations (5 × 10−6 to 500 × 10−6 mol/l) of lidocaine. The most salient result was that whereas large doses (5 × 10−4 mol/l or higher) of lidocaine were required to inhibit action potentials temporarily in single cells, much lower doses (5 × 10−6 mol/l), i.e., therapeutic levels, were sufficient to have the same effect in papillary muscles: a hundredfold difference. Our experimental results and mathematical analysis indicate that the syncytial nature of cardiac tissue explains the effects of clinically relevant doses of Na+ channel blockers. PMID:26342072

  15. Association of heart rate at hospital discharge with mortality and hospitalizations in patients with heart failure.

    PubMed

    Habal, Marlena V; Liu, Peter P; Austin, Peter C; Ross, Heather J; Newton, Gary E; Wang, Xuesong; Tu, Jack V; Lee, Douglas S

    2014-01-01

    Heart failure (HF) is associated with a high burden of morbidity and mortality. Hospital discharge is an opportunity for identification of modifiable prognostic factors in the transition to chronic HF. We examined the association of discharge heart rate with 30-day and 1-year mortality and hospitalization outcomes in a cohort of 9097 patients with HF discharged from hospital. Discharge heart rate was categorized into predefined groups: 40 to 60 (n=1333), 61 to 70 (n=2170), 71 to 80 (n=2631), 81 to 90 (n=1700), and >90 bpm (n=1263). There was a significant increase in all-cause 30-day mortality with adjusted odds ratios of 1.59 (95% confidence interval [CI], 1.18-2.14; P=0.003) for discharge heart rates 81 to 90 bpm and 1.56 (95% CI, 1.13-2.16; P=0.007) for heart rates>90 bpm when compared with the reference group (heart rates, 61-70 bpm). Cardiovascular death risk at 30 days was also higher with adjusted odds ratio 1.59 (discharge heart rates, 81-90 bpm; 95% CI, 1.09-2.33; P=0.017) and 1.65 (discharge heart rates, >90 bpm; 95% CI, 1.09-2.48; P=0.017). One-year all-cause mortality (adjusted odds ratio, 1.41; 95% CI, 1.16-1.72; P<0.001) and cardiovascular death (adjusted odds ratio, 1.47; 95% CI, 1.12-1.92; P=0.005) were higher with discharge heart rates>90 bpm when compared with the reference group (heart rates, 40-60 bpm). Readmissions for HF (adjusted hazard ratio, 1.26; 95% CI, 1.04-1.54; P=0.021) and cardiovascular disease (adjusted hazard ratio, 1.29; 95% CI, 1.08-1.54; P=0.004) within 30 days were also higher with discharge heart rates>90 bpm. Higher discharge heart rates were associated with greater risk of all-cause and cardiovascular mortality≤1-year follow-up and an elevated risk of 30-day readmission for HF and cardiovascular disease.

  16. Fruit and vegetable intake and rate of heart failure: a population-based prospective cohort of women.

    PubMed

    Rautiainen, Susanne; Levitan, Emily B; Mittleman, Murray A; Wolk, Alicja

    2015-01-01

    Although numerous studies have investigated fruit and vegetable consumption in association with cardiovascular diseases (CVD) such as coronary heart disease and stroke, a limited number of studies have investigated the association with heart failure. The aim of this study was to assess the association between fruit and vegetable intake and the incidence of heart failure among women. In September 1997, a total of 34,319 women (aged 49-83 years) from the Swedish Mammography Cohort, free of cancer and CVD at baseline, completed a food-frequency questionnaire. Women were followed for incident heart failure (diagnosis as primary or secondary cause) through December 2011 using administrative health registries. Over 12.9 years of follow-up (442,348 person-years), we identified 3051 incident cases of heart failure. Total fruit and vegetable consumption was inversely associated with the rate of heart failure {the multivariable-adjusted rate ratio (RR) in the highest quintile compared with the lowest was 0.80 [95% confidence interval (CI) 0.70-0.90]}. Fruit (mutually adjusted for vegetables) were not significantly associated with rate of heart failure (RR 0.94; 95% CI 0.83-1.07), whereas vegetables showed an inverse association (RR 0.83; 95% CI 0.73-0.95). When investigating the shape of association, we found evidence of a non-linear association (P = 0.01), and the lowest rates of heart failure were observed among women consuming ≥5 servings/day of fruit and vegetables, without further decrease with increasing intake. In this population-based prospective cohort study of women, higher total consumption of fruit and vegetables was inversely associated with the incidence of heart failure. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

  17. Heart Rate Dynamics During A Treadmill Cardiopulmonary Exercise Test in Optimized Beta-Blocked Heart Failure Patients

    PubMed Central

    Carvalho, Vitor Oliveira; Guimarães, Guilherme Veiga; Ciolac, Emmanuel Gomes; Bocchi, Edimar Alcides

    2008-01-01

    BACKGROUND Calculating the maximum heart rate for age is one method to characterize the maximum effort of an individual. Although this method is commonly used, little is known about heart rate dynamics in optimized beta-blocked heart failure patients. AIM The aim of this study was to evaluate heart rate dynamics (basal, peak and % heart rate increase) in optimized beta-blocked heart failure patients compared to sedentary, normal individuals (controls) during a treadmill cardiopulmonary exercise test. METHODS Twenty-five heart failure patients (49±11 years, 76% male), with an average LVEF of 30±7%, and fourteen controls were included in the study. Patients with atrial fibrillation, a pacemaker or noncardiovascular functional limitations or whose drug therapy was not optimized were excluded. Optimization was considered to be 50 mg/day or more of carvedilol, with a basal heart rate between 50 to 60 bpm that was maintained for 3 months. RESULTS Basal heart rate was lower in heart failure patients (57±3 bpm) compared to controls (89±14 bpm; p<0.0001). Similarly, the peak heart rate (% maximum predicted for age) was lower in HF patients (65.4±11.1%) compared to controls (98.6±2.2; p<0.0001). Maximum respiratory exchange ratio did not differ between the groups (1.2±0.5 for controls and 1.15±1 for heart failure patients; p=0.42). All controls reached the maximum heart rate for their age, while no patients in the heart failure group reached the maximum. Moreover, the % increase of heart rate from rest to peak exercise between heart failure (48±9%) and control (53±8%) was not different (p=0.157). CONCLUSION No patient in the heart failure group reached the maximum heart rate for their age during a treadmill cardiopulmonary exercise test, despite the fact that the percentage increase of heart rate was similar to sedentary normal subjects. A heart rate increase in optimized beta-blocked heart failure patients during cardiopulmonary exercise test over 65% of the

  18. Kansas City Cardiomyopathy Questionnaire Utility in Prediction of 30-Day Readmission Rate in Patients with Chronic Heart Failure

    PubMed Central

    Gui, Junhong; Zhu, Xiang; Malhotra, Divyanshu; Li, Shenjing; Virkram, Fnu; Chada, Aditya; Jiang, Haibing

    2016-01-01

    Background. Heart failure (HF) is one of the most common diagnoses associated with hospital readmission. We designed this prospective study to evaluate whether Kansas City Cardiomyopathy Questionnaire (KCCQ) score is associated with 30-day readmission in patients hospitalized with decompensated HF. Methods and Results. We enrolled 240 patients who met the study criteria. Forty-eight (20%) patients were readmitted for decompensated HF within thirty days of hospital discharge, and 192 (80%) patients were not readmitted. Compared to readmitted patients, nonreadmitted patients had a higher average KCCQ score (40.8 versus 32.6, P = 0.019) before discharge. Multivariate analyses showed that a high KCCQ score was associated with low HF readmission rate (adjusted OR = 0.566, P = 0.022). The c-statistic for the base model (age + gender) was 0.617. The combination of home medication and lab tests on the base model resulted in an integrated discrimination improvement (IDI) increase of 3.9%. On that basis, the KCQQ further increased IDI of 2.7%. Conclusions. The KCCQ score determined before hospital discharge was significantly associated with 30-day readmission rate in patients with HF, which may provide a clinically useful measure and could significantly improve readmission prediction reliability when combined with other clinical components. PMID:27872790

  19. Allograft tissue irradiation and failure rate after anterior cruciate ligament reconstruction: A systematic review

    PubMed Central

    Dashe, Jesse; Parisien, Robert L; Cusano, Antonio; Curry, Emily J; Bedi, Asheesh; Li, Xinning

    2016-01-01

    AIM: To evaluate whether anterior cruciate ligament (ACL) allograft irradiation is effective for sterility without compromising graft integrity and increasing failure rate. METHODS: A literature search was conducted using PubMed, Cochrane, and Google. The following search terms were used: “Gamma irradiation AND anterior cruciate ligament AND allograft” with a return of 30 items. Filters used included: English language, years 1990-2015. There were 6 hits that were not reviewed, as there were only abstracts available. Another 5 hits were discarded, as they did not pertain to the topic of interest. There were 9 more articles that were excluded: Three studies were performed on animals and 6 studies were meta-analyses. Therefore, a total of 10 articles were applicable to review. RESULTS: There is a delicate dosing crossover where gamma irradiation is both effective for sterility without catastrophically compromising the structural integrity of the graft. Of note, low dose irradiation is considered less than 2.0 Mrad, moderate dose is between 2.1-2.4 Mrad, and high dose is greater than or equal to 2.5 Mrad. Based upon the results of the literature search, the optimal threshold for sterilization was found to be sterilization at less than 2.2 Mrad of gamma irradiation with the important caveat of being performed at low temperatures. The graft selection process also must include thorough donor screening and testing as well as harvesting the tissue in a sterile fashion. Utilization of higher dose (≥ 2.5 Mrad) of irradiation causes greater allograft tissue laxity that results in greater graft failure rate clinically in patients after ACL reconstruction. CONCLUSION: Allograft ACL graft gamma irradiated with less than 2.2 Mrad appears to be a reasonable alternative to autograft for patients above 25 years of age. PMID:27335815

  20. Identifying Differences Between Biochemical Failure and Cure: Incidence Rates and Predictors

    SciTech Connect

    Vicini, Frank A.; Shah, Chirag; Kestin, Larry; Ghilezan, Mihai; Krauss, Daniel; Ye Hong; Brabbins, Donald; Martinez, Alvaro A.

    2011-11-15

    Background: Patients treated with radiation therapy (RT) for prostate cancer were evaluated to estimate the length of time required to document biochemical cure (BC) after treatment and the variables associated with long-term treatment efficacy. Patients and Methods: 2,100 patients received RT alone for localized prostate carcinoma (external-beam RT, n = 1,504; brachytherapy alone, n = 241; or brachytherapy + pelvic radiation, n = 355). The median external-beam dose was 68.4 Gy, and the median follow-up time was 8.6 years. Biochemical failure (BF) was defined according to the Phoenix definition. Results: Biochemical failure was experienced by 685 patients (32.6%). The median times to BF for low-, intermediate-, and high-risk groups were 6.0, 5.6, and 4.5 years respectively (p < 0.001). The average annual incidence rates of BF for years 1-5, 5-10,11-15, and 16-20 in low-risk patients were 2.0%, 2.0%, 0.3%, and 0.06% (p < 0.001); for intermediate-risk patients, 4%, 3%, 0.3%, and 0% (p < 0.001); and for high-risk patients, 10.0%, 5.0%, 0.3%, and 0.3% (p < 0.001). After 5 years of treatment, 36.9% of all patients experienced BF. The percentage of total failures occurring during years 1-5, 5-10, 11-15, and 16-20 were 48.7%, 43.5%, 6.5%, and 1.3% for low-risk patients; 64.0%, 32.2%, 3.8%, and 0% for intermediate-risk patients; and 71.9%, 25.9%, 1.1%, and 1.1% for high-risk patients, respectively. Increasing time to nadir was associated with increased time to BF. On multivariate analysis, factors significantly associated with 10-year BC included prostate-specific antigen nadir and time to nadir. Conclusions: The incidence rates for BF did not plateau until later than 10 years after treatment, suggesting that extended follow-up time is required to monitor patients after treatment. Prostate-specific antigen nadir and time to nadir have the strongest association with long-term BC.

  1. The Effect of Sensor Failure on the Attitude and Rate Estimation of MAP Spacecraft

    NASA Technical Reports Server (NTRS)

    Bar-Itzhack, Itzhack Y.; Harman, Richard R.

    2003-01-01

    This work describes two algorithms for computing the angular rate and attitude in case of a gyro and a Star Tracker failure in the Microwave Anisotropy Probe (MAP) satellite, which was placed in the L2 parking point from where it collects data to determine the origin of the universe. The nature of the problem is described, two algorithms are suggested, an observability study is carried out and real MAP data are used to determine the merit of the algorithms. It is shown that one of the algorithms yields a good estimate of the rates but not of the attitude whereas the other algorithm yields a good estimate of the rate as well as two of the three attitude angles. The estimation of the third angle depends on the initial state estimate. There is a contradiction between this result and the outcome of the observability analysis. An explanation of this contradiction is given in the paper. Although this work treats a particular spacecraft, its conclusions are more general.

  2. Clinical bond failure rates of adhesive precoated self-ligating brackets using a self-etching primer.

    PubMed

    Ozer, Mete; Bayram, Mehmet; Dincyurek, Cagri; Tokalak, Fuat

    2014-01-01

    To comparatively assess the failure rate of adhesive precoated (APC) self-ligating metal brackets bonded with two different enamel surface preparation techniques: self-etching primer (SEP) and conventional two-step etch and primer method (CM). Fifty-seven patients with complete permanent dentition were included in this study. A total of 1140 APC self-ligating brackets (3M Unitek, Monrovia, Calif) were bonded using a split-mouth design. For each patient, SEP (Transbond Plus SEP, 3M Unitek) and CM (37% phosphoric acid) were used in alternate quadrants. All brackets were bonded by the same investigator after pumicing and rinsing of all of the teeth. The number, site, and date of first-time bracket failures were monitored throughout orthodontic treatment (mean, 22 months). The survival rates of the brackets were estimated by Kaplan-Meier and log-rank tests (P < .05). The adhesive remnant index was used to determine the bond failure interface. The bond failure rates were 2.97% and 2.18% for the CM and SEP, respectively. No statistically significant difference in failure rates was found between the groups. The bond failure sites were predominantly at the enamel-adhesive interface in both groups. This long-term in vivo study showed that the combined use of SEP and the APC bracket system can be used effectively for bonding brackets after pumicing the enamel surfaces in clinical orthodontics.

  3. Effect of Selective Heart Rate Slowing in Heart Failure With Preserved Ejection Fraction.

    PubMed

    Pal, Nikhil; Sivaswamy, Nadiya; Mahmod, Masliza; Yavari, Arash; Rudd, Amelia; Singh, Satnam; Dawson, Dana K; Francis, Jane M; Dwight, Jeremy S; Watkins, Hugh; Neubauer, Stefan; Frenneaux, Michael; Ashrafian, Houman

    2015-11-03

    Heart failure with preserved ejection fraction (HFpEF) is associated with significant morbidity and mortality but is currently refractory to therapy. Despite limited evidence, heart rate reduction has been advocated, on the basis of physiological considerations, as a therapeutic strategy in HFpEF. We tested the hypothesis that heart rate reduction improves exercise capacity in HFpEF. We conducted a randomized, crossover study comparing selective heart rate reduction with the If blocker ivabradine at 7.5 mg twice daily versus placebo for 2 weeks each in 22 symptomatic patients with HFpEF who had objective evidence of exercise limitation (peak oxygen consumption at maximal exercise [o2 peak] <80% predicted for age and sex). The result was compared with 22 similarly treated matched asymptomatic hypertensive volunteers. The primary end point was the change in o2 peak. Secondary outcomes included tissue Doppler-derived E/e' at echocardiography, plasma brain natriuretic peptide, and quality-of-life scores. Ivabradine significantly reduced peak heart rate compared with placebo in the HFpEF (107 versus 129 bpm; P<0.0001) and hypertensive (127 versus 145 bpm; P=0.003) cohorts. Ivabradine compared with placebo significantly worsened the change in o2 peak in the HFpEF cohort (-2.1 versus 0.9 mL·kg(-1)·min(-1); P=0.003) and significantly reduced submaximal exercise capacity, as determined by the oxygen uptake efficiency slope. No significant effects on the secondary end points were discernable. Our observations bring into question the value of heart rate reduction with ivabradine for improving symptoms in a HFpEF population characterized by exercise limitation. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02354573. © 2015 The Authors.

  4. Heart rate variability (HRV) in kidney failure: measurement and consequences of reduced HRV.

    PubMed

    Ranpuria, Reena; Hall, Martica; Chan, Chris T; Unruh, Mark

    2008-02-01

    A common cause of death in end-stage renal disease (ESRD) patients on dialysis is sudden cardiac death (SCD). Compared to the general population, the percentage of cardiovascular deaths that are attributed to SCD is higher in patients treated by dialysis. While coronary artery disease (CAD) is the predominant cause of SCD in dialysis patients, reduced heart rate variability (HRV) may play a role in the higher risk of SCD among other risk factors. HRV refers to beat-to-beat alterations in heart rate as measured by periodic variation in the R-R interval. HRV provides a non-invasive method for investigating autonomic input into the heart. It quantifies the amount by which the R-R interval or heart rate changes from one cardiac cycle to the next. The autonomic nervous system transmits impulses from the central nervous system to peripheral organs and is responsible for controlling the heart rate, blood pressure and respiratory activity. In normal individuals, without cardiac disease, the heart rate has a high degree of beat-to-beat variability. HRV fluctuates with respiration: it increases with inspiration and decreases with expiration and is primarily mediated by parasympathetic activity. HRV has been used to evaluate and quantify the cardiac risk associated with a variety of conditions including cardiac disorders, stroke, multiple sclerosis and diabetes. In this narrative review, we will examine the association between HRV and SCD. This report explains the measurement of HRV and the consequences of reduced HRV in the general population and dialysis patients. Lastly, this review will outline the possible use of HRV as a clinical predictor for SCD in the dialysis population. The current understanding of SCD based on HRV findings among the ESRD population support the use of more aggressive treatment of CAD; greater use of angiotensin converting enzyme inhibitor (ACE-i)/angiotensin receptor blockers (ARBs) and beta-blockers and more frequent and/or nocturnal haemodialysis

  5. Effect of Selective Heart Rate Slowing in Heart Failure With Preserved Ejection Fraction

    PubMed Central

    Pal, Nikhil; Sivaswamy, Nadiya; Mahmod, Masliza; Yavari, Arash; Rudd, Amelia; Singh, Satnam; Dawson, Dana K.; Francis, Jane M.; Dwight, Jeremy S.; Watkins, Hugh; Neubauer, Stefan; Frenneaux, Michael

    2015-01-01

    Background— Heart failure with preserved ejection fraction (HFpEF) is associated with significant morbidity and mortality but is currently refractory to therapy. Despite limited evidence, heart rate reduction has been advocated, on the basis of physiological considerations, as a therapeutic strategy in HFpEF. We tested the hypothesis that heart rate reduction improves exercise capacity in HFpEF. Methods and Results— We conducted a randomized, crossover study comparing selective heart rate reduction with the If blocker ivabradine at 7.5 mg twice daily versus placebo for 2 weeks each in 22 symptomatic patients with HFpEF who had objective evidence of exercise limitation (peak oxygen consumption at maximal exercise [o2 peak] <80% predicted for age and sex). The result was compared with 22 similarly treated matched asymptomatic hypertensive volunteers. The primary end point was the change in o2 peak. Secondary outcomes included tissue Doppler–derived E/e′ at echocardiography, plasma brain natriuretic peptide, and quality-of-life scores. Ivabradine significantly reduced peak heart rate compared with placebo in the HFpEF (107 versus 129 bpm; P<0.0001) and hypertensive (127 versus 145 bpm; P=0.003) cohorts. Ivabradine compared with placebo significantly worsened the change in o2 peak in the HFpEF cohort (-2.1 versus 0.9 mL·kg−1·min−1; P=0.003) and significantly reduced submaximal exercise capacity, as determined by the oxygen uptake efficiency slope. No significant effects on the secondary end points were discernable. Conclusion— Our observations bring into question the value of heart rate reduction with ivabradine for improving symptoms in a HFpEF population characterized by exercise limitation. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT02354573. PMID:26338956

  6. High-rate laser metal deposition of Inconel 718 component using low heat-input approach

    NASA Astrophysics Data System (ADS)

    Kong, C. Y.; Scudamore, R. J.; Allen, J.

    Currently many aircraft and aero engine components are machined from billets or oversize forgings. This involves significant cost, material wastage, lead-times and environmental impacts. Methods to add complex features to another component or net-shape surface would offer a substantial cost benefit. Laser Metal Deposition (LMD), currently being applied to the repair of worn or damaged aero engine components, was attempted in this work as an alternative process route, to build features onto a base component, because of its low heat input capability. In this work, low heat input and high-rate deposition was developed to deposit Inconel 718 powder onto thin plates. Using the optimised process parameters, a number of demonstrator components were successfully fabricated.

  7. Digitally modulated bit error rate measurement system for microwave component evaluation

    NASA Technical Reports Server (NTRS)

    Shalkhauser, Mary Jo W.; Budinger, James M.

    1989-01-01

    The NASA Lewis Research Center has developed a unique capability for evaluation of the microwave components of a digital communication system. This digitally modulated bit-error-rate (BER) measurement system (DMBERMS) features a continuous data digital BER test set, a data processor, a serial minimum shift keying (SMSK) modem, noise generation, and computer automation. Application of the DMBERMS has provided useful information for the evaluation of existing microwave components and of design goals for future components. The design and applications of this system for digitally modulated BER measurements are discussed.

  8. Failure stress criterion for adhesively bonded joint at different strain rates by using dynamic Arcan test device

    NASA Astrophysics Data System (ADS)

    Dufour, Ludovic; Bourel, Benjamin; Lauro, Franck; Haugou, Gregory; Leconte, Nicolas; Carrere, Nicolas

    2015-09-01

    The purpose of this work is to determine the failure criterion evolution of assembly bonded with a strain rate dependent adhesive. A new modified ARCAN device is then designed to obtain the average stress at failure under different loading angles and for strain up to 350 s-1. Tests are performed on a hydraulic jack machine and a Digital Image Correlation measurement is used to control the opening and the sliding displacements of the two substrates.

  9. Sampling rate of spatial stochastic processes with independent components in modeling random search paths

    NASA Astrophysics Data System (ADS)

    Kawai, Reiichiro

    2012-02-01

    Continuous-time modeling of random searches is designed to be robust to the sampling rate while the spatial model is required to be of rotation-invariant type, which is often computationally prohibitive. Such computational difficulty may be circumvented by employing a model with independent components. We demonstrate that its disadvantages in statistical properties are blurred under lower frequency. We propose a quantitative criterion for choice of the sampling rate at which a spatial model with independent components resembles a rotation-invariant model. Our findings have the potential to assist the observer to employ simpler models in the continuous-time framework to avoid expensive computation required for statistical inference.

  10. Separating spatial search and efficiency rates as components of predation risk

    PubMed Central

    DeCesare, Nicholas J.

    2012-01-01

    Predation risk is an important driver of ecosystems, and local spatial variation in risk can have population-level consequences by affecting multiple components of the predation process. I use resource selection and proportional hazard time-to-event modelling to assess the spatial drivers of two key components of risk—the search rate (i.e. aggregative response) and predation efficiency rate (i.e. functional response)—imposed by wolves (Canis lupus) in a multi-prey system. In my study area, both components of risk increased according to topographic variation, but anthropogenic features affected only the search rate. Predicted models of the cumulative hazard, or risk of a kill, underlying wolf search paths validated well with broad-scale variation in kill rates, suggesting that spatial hazard models provide a means of scaling up from local heterogeneity in predation risk to population-level dynamics in predator–prey systems. Additionally, I estimated an integrated model of relative spatial predation risk as the product of the search and efficiency rates, combining the distinct contributions of spatial heterogeneity to each component of risk. PMID:22977145

  11. Skin Glue Reduces the Failure Rate of Emergency Department-Inserted Peripheral Intravenous Catheters: A Randomized Controlled Trial.

    PubMed

    Bugden, Simon; Shean, Karla; Scott, Mark; Mihala, Gabor; Clark, Sean; Johnstone, Christopher; Fraser, John F; Rickard, Claire M

    2016-08-01

    Peripheral intravenous catheters are the most common invasive device in health care yet have very high failure rates. We investigate whether the failure rate could be reduced by the addition of skin glue to standard peripheral intravenous catheter care. We conducted a single-site, 2-arm, nonblinded, randomized, controlled trial of 380 peripheral intravenous catheters inserted into 360 adult patients. The standard care group received standard securement. The skin glue group received standard securement plus cyanoacrylate skin glue applied to the skin insertion site. The primary outcome was peripheral intravenous catheter failure at 48 hours, regardless of cause. Secondary outcomes were the individual modes of peripheral intravenous catheter failure: infection, phlebitis, occlusion, or dislodgement. Peripheral intravenous catheter failure was 10% lower (95% confidence interval -18% to -2%; P=.02) with skin glue (17%) than standard care (27%), and dislodgement was 7% lower (95% confidence interval -13% to 0%; P=.04). Phlebitis and occlusion were less with skin glue but were not statistically significant. There were no infections. This study supports the use of skin glue in addition to standard care to reduce peripheral intravenous catheter failure rates for adult emergency department patients admitted to the hospital. Copyright © 2015 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

  12. Betaxolol improves the survival rate and changes natriuretic peptide expression in rats with heart failure.

    PubMed

    Watanabe, Kenichi; Juan, Wen; Narasimman, Gurusamy; Ma, Meilei; Inoue, Mikio; Saito, Yuki; Wahed, Mir I I; Nakazawa, Mikio; Hasegawa, Go; Naito, Makoto; Tachikawa, Hitoshi; Tanabe, Naohito; Kodama, Makoto; Aizawa, Yoshifusa; Yamamoto, Tadashi; Yamaguchi, Kenichi; Takahashi, Toshihiro

    2003-01-01

    The cardioprotective effects of betaxolol were studied in a rat model with heart failure induced by autoimmune myocarditis. Twenty-eight days after immunization, Lewis rats were divided into four groups; 0.1 mg/kg betaxolol per day (group 0.1), 1.0 mg/kg betaxolol per day (group 1), 10 mg/kg betaxolol per day (group 10), and vehicle (0.5% methylcellulose, group V) (all groups, n = 13). After oral administration for 1 month, the heart weight, the mRNA expression of atrial natriuretic peptide and brain natriuretic peptide in the left ventricle, the plasma atrial natriuretic peptide concentration, the mean blood pressure, the heart rate, the central venous pressure, the peak left ventricular pressure, the left ventricular end-diastolic pressure and its first derivative +/-dP/dt, and the area of myocardial fibrosis were measured. Betaxolol reduced the heart rate, the levels of atrial natriuretic peptide and brain natriuretic peptide mRNA expression and the atrial natriuretic peptide concentration [group N (normal rats), 367 +/- 4 beats/min, 100%, 100% and 78 +/- 7 pg/ml, respectively; group V, 391 +/- 9 beats/min, 761 +/- 68% versus group N, 317 +/- 42% versus group N and 4374 +/- 312 pg/ml, respectively; group 0.1, 387 +/- 10 beats/min, 621 +/- 78%, 288 +/- 41% and 2875 +/- 331 pg/ml, respectively; group 1, 323 +/- 9 beats/min, 442 +/- 84%, 148 +/- 12% and 884 +/- 51 pg/ml, respectively; and group 10, 312 +/- 8 beats/min, 97 +/- 18%, 92 + 9% and 453 +/- 53 pg/ml, respectively], and increased survival (group V, 62%; group 0.1, 69%; groups N, 1 and 10, 100%). Betaxolol did not significantly alter the heart weight, the hemodynamic parameters or the area of fibrosis. These observations suggest that betaxolol may improve the survival rate by reducing sudden death and changing the atrial natriuretic peptide and brain natriuretic peptide mRNA expression in patients with heart failure.

  13. Catheter failure rates and time course with epidural versus combined spinal-epidural analgesia in labor.

    PubMed

    Groden, J; Gonzalez-Fiol, A; Aaronson, J; Sachs, A; Smiley, R

    2016-05-01

    The combined spinal-epidural technique for labor analgesia has several advantages over the traditional epidural technique, including faster onset, greater maternal satisfaction, and decreased need for physician boluses. Proponents of the epidural technique criticize the combined spinal-epidural technique, arguing that the epidural catheter remains untested and thus may not be reliable if needed for surgical intervention. We compared failure rates and time of failure between techniques in our tertiary-care academic practice. Data regarding failed catheters were collected from October 2012 to September 2014 as part of our Quality Assurance program. Failed catheters were defined as any catheter replaced after it was considered to be properly placed and then determined to be intravascular, one sided or resulting in poor maternal analgesia or anesthesia. A total of 5487 analgesics were performed (3980 combined spinal-epidural; 1507 epidural). Eighty-five combined spinal-epidural catheters (2.1%) and 59 epidural catheters (3.9%) were replaced during labor (P<0.001). Mean time to replacement was 512±422min and 354±300min for the combined spinal-epidural (n=80) and epidural (n=57) groups, respectively (P=0.02). Median time to replacement was 398 [IQR 131-578] min and 281 [IQR 186-767] min for combined spinal-epidural and epidural groups, respectively (P<0.0001). We were able to demonstrate that catheters placed using a combined spinal-epidural technique were less likely to fail during labor and that the time to detection of a failed catheter was significantly longer in the combined spinal-epidural group. Our findings validate the combined spinal-epidural technique as reliable for labor analgesia and tend to refute the theory of the untested catheter. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Using Roadside Billboard Posters to Increase Admission Rates to Problem Gambling Services: Reflections on Failure.

    PubMed

    Calderwood, Kimberly A; Wellington, William J

    2015-07-01

    Based on the stimulus-response model of advertising, this study sought to increase admission rates to a local problem gambling service (PGS) in Windsor, Ontario, Canada, by adding a series of locally based 10 foot by 20 foot roadside billboard posters to PGS's existing communications tools for a 24-week period. Using proof of performance reports, a pre-post survey of new callers to PGS, a website visit counter, and a media awareness survey, the findings showed that at least some individuals were influenced by billboard exposure, but admission rates continued to decline during the billboard campaign period. While one possible explanation for the communications failure was that the whole PGS communications campaign was below the minimal threshold for communications perception, another possible explanation is that the stimulus-response model of advertising used may not have been appropriate for such advertising that targets behavior change. Reflections on using an information-processing model instead of a stimulus-response model, and considerations of a two-step flow of communication, are provided. Recommendations are made regarding matching communications messages to stages of behavior change, use of online promotion, and strategies for future research.

  15. Review and Analysis of Existing Mobile Phone Apps to Support Heart Failure Symptom Monitoring and Self-Care Management Using the Mobile Application Rating Scale (MARS).

    PubMed

    Masterson Creber, Ruth M; Maurer, Mathew S; Reading, Meghan; Hiraldo, Grenny; Hickey, Kathleen T; Iribarren, Sarah

    2016-06-14

    Heart failure is the most common cause of hospital readmissions among Medicare beneficiaries and these hospitalizations are often driven by exacerbations in common heart failure symptoms. Patient collaboration with health care providers and decision making is a core component of increasing symptom monitoring and decreasing hospital use. Mobile phone apps offer a potentially cost-effective solution for symptom monitoring and self-care management at the point of need. The purpose of this review of commercially available apps was to identify and assess the functionalities of patient-facing mobile health apps targeted toward supporting heart failure symptom monitoring and self-care management. We searched 3 Web-based mobile app stores using multiple terms and combinations (eg, "heart failure," "cardiology," "heart failure and self-management"). Apps meeting inclusion criteria were evaluated using the Mobile Application Rating Scale (MARS), IMS Institute for Healthcare Informatics functionality scores, and Heart Failure Society of America (HFSA) guidelines for nonpharmacologic management. Apps were downloaded and assessed independently by 2-4 reviewers, interclass correlations between reviewers were calculated, and consensus was met by discussion. Of 3636 potentially relevant apps searched, 34 met inclusion criteria. Most apps were excluded because they were unrelated to heart failure, not in English or Spanish, or were games. Interrater reliability between reviewers was high. AskMD app had the highest average MARS total (4.9/5). More than half of the apps (23/34, 68%) had acceptable MARS scores (>3.0). Heart Failure Health Storylines (4.6) and AskMD (4.5) had the highest scores for behavior change. Factoring MARS, functionality, and HFSA guideline scores, the highest performing apps included Heart Failure Health Storylines, Symple, ContinuousCare Health App, WebMD, and AskMD. Peer-reviewed publications were identified for only 3 of the 34 apps. This review suggests

  16. Review and Analysis of Existing Mobile Phone Apps to Support Heart Failure Symptom Monitoring and Self-Care Management Using the Mobile Application Rating Scale (MARS)

    PubMed Central

    Maurer, Mathew S; Reading, Meghan; Hiraldo, Grenny; Hickey, Kathleen T; Iribarren, Sarah

    2016-01-01

    Background Heart failure is the most common cause of hospital readmissions among Medicare beneficiaries and these hospitalizations are often driven by exacerbations in common heart failure symptoms. Patient collaboration with health care providers and decision making is a core component of increasing symptom monitoring and decreasing hospital use. Mobile phone apps offer a potentially cost-effective solution for symptom monitoring and self-care management at the point of need. Objective The purpose of this review of commercially available apps was to identify and assess the functionalities of patient-facing mobile health apps targeted toward supporting heart failure symptom monitoring and self-care management. Methods We searched 3 Web-based mobile app stores using multiple terms and combinations (eg, “heart failure,” “cardiology,” “heart failure and self-management”). Apps meeting inclusion criteria were evaluated using the Mobile Application Rating Scale (MARS), IMS Institute for Healthcare Informatics functionality scores, and Heart Failure Society of America (HFSA) guidelines for nonpharmacologic management. Apps were downloaded and assessed independently by 2-4 reviewers, interclass correlations between reviewers were calculated, and consensus was met by discussion. Results Of 3636 potentially relevant apps searched, 34 met inclusion criteria. Most apps were excluded because they were unrelated to heart failure, not in English or Spanish, or were games. Interrater reliability between reviewers was high. AskMD app had the highest average MARS total (4.9/5). More than half of the apps (23/34, 68%) had acceptable MARS scores (>3.0). Heart Failure Health Storylines (4.6) and AskMD (4.5) had the highest scores for behavior change. Factoring MARS, functionality, and HFSA guideline scores, the highest performing apps included Heart Failure Health Storylines, Symple, ContinuousCare Health App, WebMD, and AskMD. Peer-reviewed publications were identified

  17. The relationship between elderly suicide rates and different components of education: a cross-national study.

    PubMed

    Shah, Ajit

    2012-07-01

    Two recent studies reported a curvilinear (U-shaped) between elderly suicide rates and educational attainment measured by the United Nation's Education Index. A study examining the curvilinear (U-shaped) relationship between elderly suicide rates and the individual components of the Education Index (adult literacy rate, percentage of children of relevant age group enrolled in primary schools and percentage of children of relevant age group enrolled for secondary schools) and one other measure of educational attainment (youth literacy rate) was undertaken to partial out the effects of the individual components of Education Index on elderly suicides. A cross-national study examining the relationship between elderly suicide rates (Y-axis) and different measures of educational attainment (X-axis) was undertaken using data from the World Health Organization and the United Nations data banks using Curve estimation regression models. The relationship between elderly suicide rates with the adult literacy rate, the percentage of children of relevant age group enrolled for secondary schools and the youth literacy rate was curvilinear (U-shaped curve). This relationship was absent with the percentage of children of relevant age group enrolled in primary schools. Given the cross-sectional study design, a causal relationship between elderly suicide rates and measures of educational attainment, including the adult literacy rate, the percentage of children of relevant age group enrolled for secondary schools and the youth literacy rate, cannot be assumed. However, the findings suggest that future studies of elderly suicide rates and educational attainment should focus on the adult literacy rate, the percentage of children of relevant age group enrolled for secondary schools and the youth literacy rate as measures of educational attainment.

  18. In-Flight Validation of a Pilot Rating Scale for Evaluating Failure Transients in Electronic Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Kalinowski, Kevin F.; Tucker, George E.; Moralez, Ernesto, III

    2006-01-01

    Engineering development and qualification of a Research Flight Control System (RFCS) for the Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) JUH-60A has motivated the development of a pilot rating scale for evaluating failure transients in fly-by-wire flight control systems. The RASCAL RFCS includes a highly-reliable, dual-channel Servo Control Unit (SCU) to command and monitor the performance of the fly-by-wire actuators and protect against the effects of erroneous commands from the flexible, but single-thread Flight Control Computer. During the design phase of the RFCS, two piloted simulations were conducted on the Ames Research Center Vertical Motion Simulator (VMS) to help define the required performance characteristics of the safety monitoring algorithms in the SCU. Simulated failures, including hard-over and slow-over commands, were injected into the command path, and the aircraft response and safety monitor performance were evaluated. A subjective Failure/Recovery Rating (F/RR) scale was developed as a means of quantifying the effects of the injected failures on the aircraft state and the degree of pilot effort required to safely recover the aircraft. A brief evaluation of the rating scale was also conducted on the Army/NASA CH-47B variable stability helicopter to confirm that the rating scale was likely to be equally applicable to in-flight evaluations. Following the initial research flight qualification of the RFCS in 2002, a flight test effort was begun to validate the performance of the safety monitors and to validate their design for the safe conduct of research flight testing. Simulated failures were injected into the SCU, and the F/RR scale was applied to assess the results. The results validate the performance of the monitors, and indicate that the Failure/Recovery Rating scale is a very useful tool for evaluating failure transients in fly-by-wire flight control systems.

  19. Typical-use contraceptive failure rates in 43 countries with Demographic and Health Survey data: summary of a detailed report

    PubMed Central

    Polis, Chelsea B.; Bradley, Sarah E.K.; Bankole, Akinrinola; Onda, Tsuyoshi; Croft, Trevor; Singh, Susheela

    2016-01-01

    Background While most unintended pregnancies occur because couples do not use contraception, contraceptive failure is also an important underlying cause. However, few recent studies outside of the United States have estimated contraceptive failure rates, and most such studies have been restricted to married women, to a limited number of countries and to 12-month failure rate estimates. Methods Using self-reported data from 43 countries with Demographic and Health Survey data, we estimated typical-use contraceptive failure rates for seven contraceptive methods at 12, 24 and 36 months of use. We provide a median estimate for each method across 43 countries overall, in seven subregions and in individual countries. We assess differences by various demographic and socioeconomic characteristics. Estimates are not corrected for potential errors in retrospective reporting contraceptive use or potential underreporting of abortion, which may vary by country and subgroups within countries. Results Across all included countries, reported 12-month typical-use failure rates were lowest for users of longer-acting methods such as implants (0.6 failures per 100 episodes of use), intrauterine devices (1.4) and injectables (1.7); intermediate for users of short-term resupply methods such as oral contraceptive pills (5.5) and male condoms (5.4); and highest for users of traditional methods such as withdrawal (13.4) or periodic abstinence (13.9), a group largely using calendar rhythm. Conclusions Our findings help us to highlight those methods, subregions and population groups that may be in need of particular attention for improvements in policies and programs to address higher contraceptive failure rates. PMID:27018154

  20. An analysis of the SEU rate of microcircuits exposed by the various components of space radiation.

    PubMed

    Bashkirov, V F; Kuznetsov, N V; Nymmik, R A

    1999-06-01

    In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR particles and SEPs) to the SEU rate is discussed with an allowance for the shielding thickness.

  1. Prognostic significance of heart rate turbulence parameters in patients with chronic heart failure

    PubMed Central

    2014-01-01

    Background This study is aimed to evaluate the clinical significance of heart rate turbulence (HRT) parameters in predicting the prognosis in patients with chronic heart failure (CHF). Methods From June 2011 to December 2012, a total of 104 CHF patients and 30 healthy controls were enrolled in this study. We obtained a 24-hour Holter ECG recording to assess the HRT parameters, included turbulence onset (TO), turbulence slope (TS), standard deviation of N-N intervals (SDNN), and resting heart rate (RHR). The relationships between HRT parameters and the prognosis of CHF patients were determined. Results The assessment follow-up period lasted until January 31, 2013. The overall mortality of CHF patients was 9.6% (10/104). Our results revealed that CHF patients had higher levels of TO than those of healthy subjects, but the TS levels of CHF patients were lower than that of the control group. CHF patients with NYHA grade IV had higher HRT1/2 rate than those with NYHA grade II/III. There were statistical differences in TS, LVEF, SDNN and RHR between the non-deteriorating group and the non-survivor group. Significant differences in TS among the three groups were also found. Furthermore, CHF patients in the non-survivor group had lower levels of TS than those in the deteriorating group. Correlation analyses indicated that TO negatively correlate with SDNN, while TS positively correlated with SDNN and left ventricular ejection fraction (LVEF). We also observed negative correlations between TS and left ventricular end-diastolic cavity dimension (LVEDD), RHR, homocysteine (Hcy) and C-reactive protein (CRP). Multivariate Cox regression analysis further confirmed that LVEF (≤30%), HRT2, SDNN and RHR were independent risk factors which can indicate poor prognosis in CHF patients. Conclusions Our findings indicate that HRT may have good clinical predictive value in patients with CHF. Thus, quantifying HRT parameters could be a useful tool for predicting mortality in CHF

  2. The Creeping Pearl: Why Has the Rate of Contraceptive Failure Increased in Clinical Trials of Combined Hormonal Contraceptive Pills?

    PubMed Central

    Trussell, James; Portman, David

    2013-01-01

    BACKGROUND Despite several drawbacks, the Pearl Index continues to be the most widely used statistical measure of contraceptive failure. However, Pearl indices reported in studies of newer hormonal contraceptives appear to be increasing. STUDY DESIGN We searched PubMed and MIS databases for prospective trials evaluating oral contraceptive (OC) efficacy to examine potential factors that could contribute to increasing Pearl indices. RESULTS Numerous potential factors were identified, including an increased rate of failures of newer OCs, deficiencies in methods of calculating contraceptive failure rates, differences in study design and changes in patient populations resulting in increased rates of contraceptive failures due to the inappropriate or inconsistent use of the method. CONCLUSIONS The two most likely important contributors to the increase in Pearl indices are more frequent pregnancy testing with more sensitive tests and less adherent study populations. Because study populations appear to be increasingly representative of the likely actual users once the product is marketed, we can expect to see even higher failure rates in ongoing and future studies. This result poses challenges for companies and regulatory agencies. PMID:23683581

  3. Pyrolysis characteristics of organic components of municipal solid waste at high heating rates.

    PubMed

    Zheng, Jiao; Jin, Yu-Qi; Chi, Yong; Wen, Jun-Ming; Jiang, Xu-Guang; Ni, Ming-Jiang

    2009-03-01

    The pyrolysis characteristics of six representative organic components of municipal solid waste (MSW) and their mixtures were studied in a specially designed thermogravimetric analysis apparatus with a maximum recorded heating rate of 864.8 degrees Cmin(-1). The pyrolysis behavior of individual components was described by the Avrami-Erofeev equation. The influence of final temperature on individual components was studied, and it was concluded that final temperature was a factor in reaction speed and intensity, but that it played only a limited role in determining the reaction mechanism. The interactions between different components were evaluated, and it was concluded that the interaction between homogeneous materials was minimal, whereas the interaction between polyethylene and biomass was significant.

  4. Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components.

    PubMed

    Noulsri, Egarit; Lerdwana, Surada; Kittisares, Kulvara; Palasuwan, Attakorn; Palasuwan, Duangdao

    2017-07-18

    Cell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. The current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). The accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs' fold-changes were calculated to assess the homogeneity of the blood components. Comparing the platelet counts conducted by automated counting and flow-rate calibration showed an r(2) of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland-Altman plot showed a mean bias of -31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. The results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Six-month bracket failure rate with a flowable composite: A split-mouth randomized controlled trial

    PubMed Central

    Krishnan, Sindhuja; Pandian, Saravana; Rajagopal, R.

    2017-01-01

    ABSTRACT INTRODUCTION: The use of flowable composites as an orthodontic bonding adhesive merits great attention because of their adequate bond strength, ease of clinical handling and reduced number of steps in bonding. OBJECTIVE: The aim of this Randomized Controlled Trial was to comparatively evaluate over a 6-month period the bond failure rate of a flowable composite (Heliosit Orthodontic, Ivoclar Vivadent AG, Schaan) and a conventional orthodontic bonding adhesive (Transbond XT, 3M Unitek). METHODS: 53 consecutive patients (23 males and 30 females) who fulfilled the inclusion and exclusion criteria were included in the study. A total of 891 brackets were analyzed, where 444 brackets were bonded using Heliosit Orthodontic and 447 brackets were bonded using Transbond XT. The survival rates of brackets were estimated with the Kaplan-Meier analysis. Bracket survival distributions for bonding adhesives, tooth location and dental arch were compared with the log-rank test. RESULTS: The failure rates of the Transbond XT and the Heliosit Orthodontic groups were 8.1% and 6% respectively. No significant differences in the survival rates were observed between them (p= 0.242). There was no statistically significant difference in the bond failure rates when the clinical performance of the maxillary versus the mandibular arches and the anterior versus the posterior segments were compared. CONCLUSIONS: Both systems had clinically acceptable bond failure rates and are adequate for orthodontic bonding needs. PMID:28658358

  6. Six-month bracket failure rate with a flowable composite: A split-mouth randomized controlled trial.

    PubMed

    Krishnan, Sindhuja; Pandian, Saravana; Rajagopal, R

    2017-01-01

    The use of flowable composites as an orthodontic bonding adhesive merits great attention because of their adequate bond strength, ease of clinical handling and reduced number of steps in bonding. The aim of this Randomized Controlled Trial was to comparatively evaluate over a 6-month period the bond failure rate of a flowable composite (Heliosit Orthodontic, Ivoclar Vivadent AG, Schaan) and a conventional orthodontic bonding adhesive (Transbond XT, 3M Unitek). 53 consecutive patients (23 males and 30 females) who fulfilled the inclusion and exclusion criteria were included in the study. A total of 891 brackets were analyzed, where 444 brackets were bonded using Heliosit Orthodontic and 447 brackets were bonded using Transbond XT. The survival rates of brackets were estimated with the Kaplan-Meier analysis. Bracket survival distributions for bonding adhesives, tooth location and dental arch were compared with the log-rank test. The failure rates of the Transbond XT and the Heliosit Orthodontic groups were 8.1% and 6% respectively. No significant differences in the survival rates were observed between them (p= 0.242). There was no statistically significant difference in the bond failure rates when the clinical performance of the maxillary versus the mandibular arches and the anterior versus the posterior segments were compared. Both systems had clinically acceptable bond failure rates and are adequate for orthodontic bonding needs.

  7. Multi-elemental nanoparticle exposure after tantalum component failure in hip arthroplasty: In-depth analysis of a single case.

    PubMed

    Schoon, Janosch; Geißler, Sven; Traeger, Juliane; Luch, Andreas; Tentschert, Jutta; Perino, Giorgio; Schulze, Frank; Duda, Georg N; Perka, Carsten; Rakow, Anastasia

    2017-08-16

    Porous tantalum components are widely used for complex acetabular reconstructions in revision hip arthroplasty. Multiple other metal alloys such as titanium-aluminum-vanadium or cobalt-chromium-molybdenum are principally used in artificial joint setups. We report a case of tantalum component failure being both cause and effect of a multiple metal exposure. Our aims were to assess and to characterize associated particle exposure and biological consequences. Metal level quantification revealed substantial in vivo exposure to particulate and dissociated tantalum, zirconium, chromium, cobalt, molybdenum, titanium, aluminum and vanadium in periprosthetic compartments. Aside from micron-sized particles, nanoparticles of a broad size range and elemental composition were obtained. Histological exams verified a spectrum of necrotic changes in the periprosthetic tissues. In the presented case tantalum release was accompanied by concomitance of particles originating from other utilized metals. We conclude that an overall in vivo exposure assessment is mandatory for realistic appraisal of metal toxicity and associated risks. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. A method for intermediate strain rate compression testing and study of compressive failure mechanism of Mg-Al-Zn alloy

    NASA Astrophysics Data System (ADS)

    Gupta, Nikhil; Luong, Dung D.; Rohatgi, Pradeep K.

    2011-05-01

    Obtaining meaningful information from the test results is a challenge in the split-Hopkinson pressure bar (SHPB) test method if the specimen does not fail during the test. Although SHPB method is now widely used for high strain rate testing, this limitation has made it difficult to use it for characterization of materials in the intermediate strain rate range (typically 10-1000 s-1). In the present work, a method is developed to characterize materials in the intermediate strain rate range using SHPB setup. In this method, the specimen is repeatedly tested under compression at a given strain rate until failure is achieved. The stress-strain graphs obtained from each test cycle are used to plot the master stress-strain graph for that strain rate. This method is used to study the strain rate dependence of compressive response of a Mg-Al-Zn alloy in the intermediate strain rate range. A remarkable difference is observed in the failure mechanism of the alloy under quasi-static and intermediate strain rate compression. Matrix cracking is the main failure mechanism under quasi-static compression, whereas shattering of intermetallic precipitates, along with plastic deformation of the matrix, is discovered to become prominent as the strain rate is increased.

  9. Poor quality evidence suggests that failure rates for atraumatic restorative treatment and conventional amalgam are similar.

    PubMed

    Hurst, Dominic

    2012-06-01

    The Medline, Cochrane CENTRAL, Biomed Central, Database of Open Access Journals (DOAJ), OpenJ-Gate, Bibliografia Brasileira de Odontologia (BBO), LILACS, IndMed, Sabinet, Scielo, Scirus (Medicine), OpenSIGLE and Google Scholar databases were searched. Hand searching was performed for journals not indexed in the databases. References of included trials were checked. Prospective clinical trials with test and control groups with a follow up of at least one year were included. Data abstraction was conducted independently and clinical and methodologically homogeneous data were pooled using a fixed-effects model. Eighteen trials were included. From these 32 individual dichotomous datasets were extracted and analysed. The majority of the results show no differences between both types of intervention. A high risk of selection-, performance-, detection- and attrition bias was identified. Existing research gaps are mainly due to lack of trials and small sample size. The current evidence indicates that the failure rate of high-viscosity GIC/ART restorations is not higher than, but similar to that of conventional amalgam fillings after periods longer than one year. These results are in line with the conclusions drawn during the original systematic review. There is a high risk that these results are affected by bias, and thus confirmation by further trials with suitably high numbers of participants is needed.

  10. Deceleration and acceleration capacities of heart rate associated with heart failure with high discriminating performance

    PubMed Central

    Hu, Wei; Jin, Xian; Zhang, Peng; Yu, Qiang; Yin, Guizhi; Lu, Yi; Xiao, Hongbing; Chen, Yueguang; Zhang, Dadong

    2016-01-01

    Accurate measurements of autonomic nerve regulation in heart failure (HF) were unresolved. The discriminating performance of deceleration and acceleration capacities of heart rate in HF was evaluated in 130 HF patients and 212 controls. Acceleration capacity and deceleration capacity were independent risk factors for HF in males, evaluated by multiple logistic regression analysis, with odds ratios (ORs) of 5.94 and 0.13, respectively. Acceleration capacity was also an independent risk factor for HF in females, with an OR of 8.58. Deceleration capacity was the best cardiac electrophysiological index to classify HF in males, with an area under the receiver operating characteristic curve (AUC) of 0.88. Deceleration capacity was the best classification factor of HF in females with an AUC of 0.97, significantly higher than even left ventricular ejection fraction (LVEF). Acceleration capacity also showed high performance in classifying HF in males (0.84) and females (0.92). The cut-off values of deceleration capacity for HF classification in males and females were 4.55 ms and 4.85 ms, respectively. The cut-off values of acceleration capacity for HF classification in males and females were −6.15 ms and −5.75 ms, respectively. Our study illustrates the role of acceleration and deceleration capacity measurements in the neuro-pathophysiology of HF. PMID:27005970

  11. Deceleration and acceleration capacities of heart rate associated with heart failure with high discriminating performance.

    PubMed

    Hu, Wei; Jin, Xian; Zhang, Peng; Yu, Qiang; Yin, Guizhi; Lu, Yi; Xiao, Hongbing; Chen, Yueguang; Zhang, Dadong

    2016-03-23

    Accurate measurements of autonomic nerve regulation in heart failure (HF) were unresolved. The discriminating performance of deceleration and acceleration capacities of heart rate in HF was evaluated in 130 HF patients and 212 controls. Acceleration capacity and deceleration capacity were independent risk factors for HF in males, evaluated by multiple logistic regression analysis, with odds ratios (ORs) of 5.94 and 0.13, respectively. Acceleration capacity was also an independent risk factor for HF in females, with an OR of 8.58. Deceleration capacity was the best cardiac electrophysiological index to classify HF in males, with an area under the receiver operating characteristic curve (AUC) of 0.88. Deceleration capacity was the best classification factor of HF in females with an AUC of 0.97, significantly higher than even left ventricular ejection fraction (LVEF). Acceleration capacity also showed high performance in classifying HF in males (0.84) and females (0.92). The cut-off values of deceleration capacity for HF classification in males and females were 4.55 ms and 4.85 ms, respectively. The cut-off values of acceleration capacity for HF classification in males and females were -6.15 ms and -5.75 ms, respectively. Our study illustrates the role of acceleration and deceleration capacity measurements in the neuro-pathophysiology of HF.

  12. The Performance of Short-Term Heart Rate Variability in the Detection of Congestive Heart Failure

    PubMed Central

    Barros, Allan Kardec; Ohnishi, Noboru

    2016-01-01

    Congestive heart failure (CHF) is a cardiac disease associated with the decreasing capacity of the cardiac output. It has been shown that the CHF is the main cause of the cardiac death around the world. Some works proposed to discriminate CHF subjects from healthy subjects using either electrocardiogram (ECG) or heart rate variability (HRV) from long-term recordings. In this work, we propose an alternative framework to discriminate CHF from healthy subjects by using HRV short-term intervals based on 256 RR continuous samples. Our framework uses a matching pursuit algorithm based on Gabor functions. From the selected Gabor functions, we derived a set of features that are inputted into a hybrid framework which uses a genetic algorithm and k-nearest neighbour classifier to select a subset of features that has the best classification performance. The performance of the framework is analyzed using both Fantasia and CHF database from Physionet archives which are, respectively, composed of 40 healthy volunteers and 29 subjects. From a set of nonstandard 16 features, the proposed framework reaches an overall accuracy of 100% with five features. Our results suggest that the application of hybrid frameworks whose classifier algorithms are based on genetic algorithms has outperformed well-known classifier methods. PMID:27891509

  13. Deep breathing heart rate variability is associated with inspiratory muscle weakness in chronic heart failure.

    PubMed

    Reis, Michel Silva; Arena, Ross; Archiza, Bruno; de Toledo, Carlos Fischer; Catai, Aparecida Maria; Borghi-Silva, Audrey

    2014-03-01

    There is a synchronism between the respiratory and cardiac cycles. However, the relationship of inspiratory muscle weakness in chronic heart failure (CHF) on cardiac autonomic modulation is unknown. The purpose of the present investigation was to evaluate the impact of inspiratory muscle strength on the magnitude of respiratory sinus arrhythmia. Ten CHF (62 ± 7 years--left ventricle eject fraction of 40 ± 5% and New York Heart Association class I-III) and nine matched-age healthy volunteers (64 ± 5 years) participated in this study. Heart rate variability (HRV) was obtained at rest and during deep breathing manoeuvre (DB-M) by electrocardiograph. CHF patients demonstrated impaired cardiac autonomic modulation at rest and during DB-M when compared with healthy subjects (p < 0.05). Moreover, significant and positive correlations between maximal inspiratory pressure and inspiratory-expiratory differences (r = 0.79), expiratory/inspiratory ratio (r = 0.83), root mean square of the successive differences (r = 0.77), standard deviation of NN intervals (r = 0.77), low frequency (r = 0.77), and high frequency (r = 0.70) were found during DB-M. At rest, significant correlations were found also. Patients with CHF presented impaired cardiac autonomic modulation at rest. In addition, cardiac autonomic control of heart rate was associated with inspiratory muscle weakness in CHF. Based on this evidence, recommendations for future research applications of respiratory muscle training can bring to light a potentially valuable target for rehabilitation. Copyright © 2013 John Wiley & Sons, Ltd.

  14. Executive function moderates the relationship between depressive symptoms and resting heart rate variability in heart failure.

    PubMed

    Gathright, Emily C; Walter, Fawn A; Hawkins, Misty A W; Spitznagel, Mary Beth; Hughes, Joel W; Gunstad, John

    2016-04-01

    Heart failure (HF) is associated with high rates of depression. In turn, depression is associated with reduced heart rate variability (HRV), a marker of parasympathetic dysfunction and poorer cardiac outcomes. Cognitive impairment--especially executive dysfunction--is also highly prevalent in HF, but it is unknown whether executive function (EF) impacts the depression-HRV relationship. The primary objective of this paper is to examine whether EF moderates the relationship between depression and HRV in HF. Participants were 109 HF patients. Depressive symptoms were measured using the Beck Depression Inventory-II. EF was assessed using a composite of age-adjusted T scores on the Frontal Assessment Battery, Trail Making Test B, and Stroop Color Word subtest. Parasympathetic function was assessed using resting high frequency HRV (HF-HRV). Multiple hierarchical regression was used to conduct BDI × EF moderation analyses. BDI scores were associated with reduced resting HF-HRV (p < .05). No main effects were detected between EF and resting HF-HRV (p > .05). However, EF moderated the relationship between BDI scores and resting HF-HRV (β = 0.59, p < .01). Simple slope analyses revealed that among participants with poorer EF, higher BDI scores were associated with lower resting HF-HRV (p < .001). Structural brain changes common in HF may contribute to lower EF, increased depression, and poorer autonomic functioning. Alternatively, the results may indicate that individuals with intact EF engage in self-care strategies that negate the detrimental impact of depression on autonomic function. Additional work is needed to clarify these possibilities and the potential benefits of treating depression in HF patients with different cognitive abilities.

  15. High rate of failure of allograft reconstruction of the extensor mechanism after total knee arthroplasty.

    PubMed

    Leopold, S S; Greidanus, N; Paprosky, W G; Berger, R A; Rosenberg, A G

    1999-11-01

    Disruption of the extensor mechanism is an uncommon but devastating complication of total knee arthroplasty. Several techniques for reconstruction of the extensor mechanism after total knee arthroplasty have been reported, but we do not know of any study in which the results of one group's method were corroborated by a second group using the same technique. In the present series, we evaluated the results of reconstruction of the extensor mechanism with use of allograft according to the method described by Emerson et al. Seven reconstructions of the extensor mechanism with use of a bone-tendon-bone allograft were performed with the technique of Emerson et al. in six patients. The patients were evaluated before and after the operation. The knee score according to the system of The Hospital for Special Surgery, evidence of an extensor lag, use of walking aids, and the ambulatory status of each patient were recorded. The patients were also asked about, and the medical records were reviewed for, episodes of falling related to weakness of the quadriceps after the reconstruction. The mean duration of follow-up was thirty-nine months (range, six to 115 months). As these reconstructions often fail early, the minimum duration of follow-up was six months. All seven reconstructions were rated as clinical failures on the basis of a persistent or recurrent extensor lag of more than 30 degrees. All but one patient needed an assistive device full time for walking, and four patients (five knees) had at least one documented episode of falling that was due to giving-way of the affected knee. Four of the reconstructions were revised; one revision was performed with use of another extensor mechanism allograft and three were performed with use of a medial gastrocnemius rotation flap. The other three clinical failures had not been revised at the time of writing. At the time of the most recent follow-up (or at the time of revision of the extensor reconstruction), the mean extensor lag was

  16. Ejaculate components delay reproductive senescence while elevating female reproductive rate in an insect

    PubMed Central

    Reinhardt, Klaus; Naylor, Richard A.; Siva-Jothy, Michael T.

    2009-01-01

    Increased female reproductive rates usually result in accelerated senescence. This correlation provides a link between the evolutionary conflict of the sexes and aging when ejaculate components elevate female reproductive rates at the cost of future reproduction. It is not clear whether this female cost is manifest as shorter lifespan or an earlier onset or a steeper rate of reproductive senescence. It also is unclear whether beneficial ejaculates release females from reproductive trade-offs and, if so, which senescence parameters are affected. We examined these issues in the bedbug, Cimex lectularius, a long-lived insect that shows reduced female lifespan as well as female reproductive senescence at the male-determined mating frequency. We demonstrate experimentally that, independently of the mating frequency, females receiving more ejaculate show increased reproductive rates and enter reproductive senescence later than females receiving less ejaculate. The rate of reproductive senescence did not differ between treatments, and reproductive rates did not predict mortality. The ejaculate effects were consistent in inter- and intra-population crosses, suggesting they have not evolved recently and are not caused by inbreeding. Our results suggest that ejaculate components compensate for the costs of elevated female reproductive rates in bedbugs by delaying the onset of reproductive senescence. Ejaculate components that are beneficial to polyandrous females could have arisen because male traits that protect the ejaculate have positive pleiotropic effects and/or because female counteradaptations to antagonistic male traits exceed the neutralization of those traits. That males influence female reproductive senescence has important consequences for trade-offs between reproduction and longevity and for studies of somatic senescence. PMID:19996174

  17. Ejaculate components delay reproductive senescence while elevating female reproductive rate in an insect.

    PubMed

    Reinhardt, Klaus; Naylor, Richard A; Siva-Jothy, Michael T

    2009-12-22

    Increased female reproductive rates usually result in accelerated senescence. This correlation provides a link between the evolutionary conflict of the sexes and aging when ejaculate components elevate female reproductive rates at the cost of future reproduction. It is not clear whether this female cost is manifest as shorter lifespan or an earlier onset or a steeper rate of reproductive senescence. It also is unclear whether beneficial ejaculates release females from reproductive trade-offs and, if so, which senescence parameters are affected. We examined these issues in the bedbug, Cimex lectularius, a long-lived insect that shows reduced female lifespan as well as female reproductive senescence at the male-determined mating frequency. We demonstrate experimentally that, independently of the mating frequency, females receiving more ejaculate show increased reproductive rates and enter reproductive senescence later than females receiving less ejaculate. The rate of reproductive senescence did not differ between treatments, and reproductive rates did not predict mortality. The ejaculate effects were consistent in inter- and intra-population crosses, suggesting they have not evolved recently and are not caused by inbreeding. Our results suggest that ejaculate components compensate for the costs of elevated female reproductive rates in bedbugs by delaying the onset of reproductive senescence. Ejaculate components that are beneficial to polyandrous females could have arisen because male traits that protect the ejaculate have positive pleiotropic effects and/or because female counteradaptations to antagonistic male traits exceed the neutralization of those traits. That males influence female reproductive senescence has important consequences for trade-offs between reproduction and longevity and for studies of somatic senescence.

  18. Graft Rejection Rate and Graft Failure Rate of Penetrating Keratoplasty (PKP) vs Lamellar Procedures: A Systematic Review

    PubMed Central

    Akanda, Zarique Z.; Naeem, Abdul; Russell, Elizabeth; Belrose, Jillian; Si, Francie F.; Hodge, William G.

    2015-01-01

    Purpose The aim of our investigation was to conduct a quantitative meta-analysis of the present world literature comparing the major surgical outcomes of penetrating keratoplasty (PKP) to lamellar procedures. Our goal is that clinicians, eye bank administrators, and health policy makers will be able to utilize this study in implementing decisions in regards to corneal transplantation. Methods Pooled measures of association were with odds ratios and because of study heterogeneity, the pooled effects were assumed to follow a random effects model (DerSimonian-Laird). The comparisons were between 1) PKP’s and all lamellar procedures (anterior AND posterior) and then 2) between PKP’s and all anterior lamellar procedures and 3) PKP and all posterior lamellar procedures. Results For PKP vs anterior lamellar procedures, the pooled odds ratio for rejection of PKP over lamellar keratoplasty (LK) was 3.56 (95% CI: 1.76-7.20) and for outright failure, the pooled odds ratio of PKP failure vs LK was 2.85 (95% CI: 0.84-9.66). For posterior lamellar procedures, the pooled odds ratio for rejection of PKP over LK was 1.52 (95% CI: 1.00-2.32). The pooled odds ratio for outright failure of PKP over posterior lamellar procedures was 2.09 (95% CI: 0.57-7.59). The follow up time was significantly longer for full transplants than for lamellar procedures. Conclusions For both anterior and posterior lamellar procedures, the odds ratios comparing rejection of full transplants to lamellar procedures (both anterior and posterior individually) were significantly higher in the PKP group. For outright failure, the PKP group also had a higher risk of failure than the lamellar groups but this was not statistically significant in either instance (anterior or posterior). Some of the clinical differences benefitting lamellar procedures may at least be partly explained by follow up time differences between groups and this needs to be accounted for more rigorously in future studies. PMID:25781319

  19. Estimating the Probability of Human Error by Incorporating Component Failure Data from User-Induced Defects in the Development of Complex Electrical Systems.

    PubMed

    Majewicz, Peter J; Blessner, Paul; Olson, Bill; Blackburn, Timothy

    2017-04-05

    This article proposes a methodology for incorporating electrical component failure data into the human error assessment and reduction technique (HEART) for estimating human error probabilities (HEPs). The existing HEART method contains factors known as error-producing conditions (EPCs) that adjust a generic HEP to a more specific situation being assessed. The selection and proportioning of these EPCs are at the discretion of an assessor, and are therefore subject to the assessor's experience and potential bias. This dependence on expert opinion is prevalent in similar HEP assessment techniques used in numerous industrial areas. The proposed method incorporates factors based on observed trends in electrical component failures to produce a revised HEP that can trigger risk mitigation actions more effectively based on the presence of component categories or other hazardous conditions that have a history of failure due to human error. The data used for the additional factors are a result of an analysis of failures of electronic components experienced during system integration and testing at NASA Goddard Space Flight Center. The analysis includes the determination of root failure mechanisms and trend analysis. The major causes of these defects were attributed to electrostatic damage, electrical overstress, mechanical overstress, or thermal overstress. These factors representing user-induced defects are quantified and incorporated into specific hardware factors based on the system's electrical parts list. This proposed methodology is demonstrated with an example comparing the original HEART method and the proposed modified technique. © 2017 Society for Risk Analysis.

  20. Adiponectin, insulin sensitivity, beta-cell function, and racial/ethnic disparity in treatment failure rates in TODAY

    USDA-ARS?s Scientific Manuscript database

    The Treatment Options for type 2 Diabetes in Adolescents and Youth (TODAY) study demonstrated that glycemic failure rates in the three treatments combined – metformin plus rosiglitazone, metformin alone, and metformin plus lifestyle – were higher in non-Hispanic blacks (NHB; 52.8%) versus non-Hispan...

  1. Reduced withdrawal and failure rates of accelerated nursing students enrolled in pharmacology is associated with a supportive intervention.

    PubMed

    Doggrell, Sheila Anne; Schaffer, Sally

    2016-02-01

    To reduce nursing shortages, accelerated nursing programs are available for domestic and international students. However, the withdrawal and failure rates from these programs may be different than for the traditional programs. The main aim of our study was to improve the retention and experience of accelerated nursing students. The academic background, age, withdrawal and failure rates of the accelerated and traditional students were determined. Data from 2009 and 2010 were collected prior to intervention. In an attempt to reduce the withdrawal of accelerated students, we set up an intervention, which was available to all students. The assessment of the intervention was a pre-post-test design with non-equivalent groups (the traditional and the accelerated students). The elements of the intervention were a) a formative website activity of some basic concepts in anatomy, physiology and pharmacology, b) a workshop addressing study skills and online resources, and c) resource lectures in anatomy/physiology and microbiology. The formative website and workshop was evaluated using questionnaires. The accelerated nursing students were five years older than the traditional students (p < 0.0001). The withdrawal rates from a pharmacology course are higher for accelerated nursing students, than for traditional students who have undertaken first year courses in anatomy and physiology (p = 0.04 in 2010). The withdrawing students were predominantly the domestic students with non-university qualifications or equivalent experience. The failure rates were also higher for this group, compared to the traditional students (p = 0.05 in 2009 and 0.03 in 2010). In contrast, the withdrawal rates for the international and domestic graduate accelerated students were very low. After the intervention, the withdrawal and failure rates in pharmacology for domestic accelerated students with non-university qualifications were not significantly different than those of traditional

  2. Flow rate and inorganic components of submandibular saliva in cystic fibrosis

    PubMed Central

    Blomfield, Jeanette; Warton, Kathryn L.; Brown, J. M.

    1973-01-01

    The inorganic components of submandibular saliva were determined in 35 patients with cystic fibrosis and in 28 controls. No differences due to flow rate were apparent between the two groups. At comparable flow rates, cystic fibrosis submandibular saliva had higher concentrations of calcium, sodium, and chloride, and similar concentrations of magnesium, inorganic phosphate, potassium, copper, and zinc. The insoluble, turbid fraction of the cystic fibrosis submandibular saliva contained both calcium and phosphate, and these were precipitated in a ratio which was consistent with hydroxyapatite. The secretory granules are postulated as the source of the excess calcium in cystic fibrosis submandibular saliva. PMID:4705932

  3. Analysis of Shock and High-Rate Data for Ceramics: Strength and Failure of Brittle Solids

    DTIC Science & Technology

    2007-07-01

    Fracture Damage............................................................................... 31 Residual Projectile Velocity... Fracture ............................................................................................ 36 VI Closure...Project No. 17168 2 exploration of ceramic strength in the ballistic event – in particular the failure, or fracture , wave phenomena. Another objective is

  4. Functional outcome in chronic heart failure after exercise training: Possible predictive value of heart rate variability.

    PubMed

    Ricca-Mallada, Roberto; Migliaro, Edurado R; Silvera, Gabriela; Chiappella, Lilian; Frattini, Rossana; Ferrando-Castagnetto, Federico

    2017-04-01

    Controlled exercise training (ET) is a valuable therapeutic addition to pharmacological treatment in most patients with chronic heart failure (CHF), reducing long-term mortality, preventing cardiac remodelling and improving functional capacity. Despite the fact that the mechanism underlying its benefits might be multifactorial, a sustained improvement in autonomic balance is usually attributed as a major effect. Nevertheless, not all eligible subjects show the same response to ET, probably due to several differences in the subpopulations enrolled. We hypothesize that some heart rate variability (HRV) indexes could be valid tools to optimize the selection and follow-up of CHF patients receiving ET intervention. Forty patients with CHF and left ventricular ejection fraction (LVEF)≤40% under complete evidence-based pharmacological treatment were included; 20 were assigned to a program of controlled ET on a 3-times/week basis during 24 weeks, training group (TG) and 20 received a standard follow-up program, control group (CG). In each patient, full clinical assessments, echocardiography, HRV analysis and 6-minute-walk test were performed at the beginning and the end of the study. After 24 weeks, patients in the TG showed a significant improvement in LVEF, 6-minute walk test, functional class of symptoms and HRV parasympathetic related indices (HF and rMSSD). Patients in the CG did not exhibit any improvement in the aforementioned indices and experienced more adverse events. Moreover, an initial value of HF<150 ms(2)/Hz or rMSSD<20ms predicted better outcomes of the ET program, including improvements in systolic function, the distance walked in 6minutes, and the functional class of symptoms, along with a reduction in clinical events. In CHF patients, HRV indexes related to parasympathetic function are valid and clinically useful tools to select and follow-up those candidates that could experience superior functional improvement after ET. Copyright © 2016 Elsevier

  5. Preserved autonomic heart rate modulation in chronic renal failure patients in response to hemodialysis and orthostatism.

    PubMed

    Lerma, Claudia; González, Hortensia; Pérez-Grovas, Hector; José, Marco V; Infante, Oscar

    2015-04-01

    The aim of this work was to measure the impact of active orthostatism and hemodialysis (HD) upon heart rate variability (HRV) in chronic renal failure (CRF) patients before and after HD. Nineteen healthy subjects (age 27 ± 8 years old, 13 were female) and 19 unmedicated CRF patients with HD thrice per week (average HD vintage = 12 months, age 32 ± 9 years old, 11 were female) were included. Five-minute length HRV time series were obtained during supine position and orthostatism. Recordings from CRF patients were obtained before and after HD. Time domain and frequency domain HRV indexes were compared by analysis of variance. The correlation between each HRV index and change in sympathetic weighting induced by different maneuvers was tested by Kendall's Tau correlation. A p value <0.05 was considered statistically significant. HRV indexes which are associated with sympathetic activity increased in response to orthostatism in the healthy group, e.g., low-frequency to high-frequency (LF/HF) ratio, Ln (LF/HF) = -0.3 ± 0.9 versus 0.9 ± 0.9. CRF patients before HD had higher sympathetic weighting than healthy participants, even in supine position, Ln (LF/HF) = 0.6 ± 1.0, but such a difference was accentuated during orthostatism, Ln (LF/HF) = 1.5 ± 1.0, and after HD: Ln (LF/HF) = 0.8 ± 1.3 (supine position) and 2.5 ± 2.1 (orthostatism). All HRV indexes were associated with increments in sympathetic weighting between maneuvers (Kendall's correlations absolute values ≥ 0.24). Unmedicated young CRF patients treated with hemodynamically stable maintenance HD showed preserved capacity of autonomic response (with gradual sympathetic increases) induced by cardiovascular challenges such as orthostatism and HD.

  6. Plerixafor as preemptive strategy results in high success rates in autologous stem cell mobilization failure.

    PubMed

    Worel, Nina; Fritsch, Gerhard; Agis, Hermine; Böhm, Alexandra; Engelich, Georg; Leitner, Gerda C; Geissler, Klaus; Gleixner, Karoline; Kalhs, Peter; Buxhofer-Ausch, Veronika; Keil, Felix; Kopetzky, Gerhard; Mayr, Viktor; Rabitsch, Werner; Reisner, Regina; Rosskopf, Konrad; Ruckser, Reinhard; Zoghlami, Claudia; Zojer, Niklas; Greinix, Hildegard T

    2016-08-31

    Plerixafor in combination with granulocyte-colony stimulating factor (G-CSF) is approved for autologous stem cell mobilization in poor mobilizing patients with multiple myeloma or malignant lymphoma. The purpose of this study was to evaluate efficacy and safety of plerixafor in an immediate rescue approach, administrated subsequently to G-CSF alone or chemotherapy and G-CSF in patients at risk for mobilization failure. Eighty-five patients mobilized with G-CSF alone or chemotherapy were included. Primary endpoint was the efficacy of the immediate rescue approach of plerixafor to achieve ≥2.0 × 10(6) CD34(+) cells/kg for a single or ≥5 × 10(6) CD34(+) cells/kg for a double transplantation and potential differences between G-CSF and chemotherapy-based mobilization. Secondary objectives included comparison of stem cell graft composition including CD34(+) cell and lymphocyte subsets with regard to the mobilization regimen applied. No significant adverse events were recorded. A median 3.9-fold increase in CD34(+) cells following plerixafor was observed, resulting in 97% patients achieving at least ≥2 × 10(6) CD34+ cells/kg. Significantly more differentiated granulocyte and monocyte forming myeloid progenitors were collected after chemomobilization whereas more CD19(+) and natural killer cells were collected after G-CSF. Fifty-two patients underwent transplantation showing rapid and durable engraftment, irrespectively of the stem cell mobilization regimen used. The addition of plerixafor in an immediate rescue model is efficient and safe after both, G-CSF and chemomobilization and results in extremely high success rates. Whether the differences in graft composition have a clinical impact on engraftment kinetics, immunologic recovery, and graft durability have to be analysed in larger prospective studies.

  7. Prognostic impact of heart rate in elderly with systolic heart failure and concomitant atrial fibrillation.

    PubMed

    Barywani, Salim; Petzold, Max

    2017-08-01

    The present study aimed to investigate the impact of resting heart rate (HR) on 5-year all-cause mortality in patients ≥80 years with heart failure (HF) with reduced ejection fraction (HFrEF) and concomitant atrial fibrillation (AF) after optimal up-titration of beta-blockers (BBs). Patients (n = 185) aged ≥80 years with HF and left ventricular ejection fraction ≤40% were included between January 2000 and January 2008 from two university hospitals, Sahlgrenska and Östra and retrospectively studied from January 2 to May 30, 2013. Up-titrations of guideline recommended medications were performed at HF outpatient clinics. Of whole study population, 54% (n= 100) had AF. After optimal up-titration of BBs and angiotensin converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs), mean HR in patients with AF was 73 ± 15 beats/minute (bpm), 36% had resting HR ≤65 bpm. Five-year all-cause mortality among patients with AF was significantly lower in patients with HR ≤65 bpm (63%) compared to HR >65 (80%). Cox proportional-hazard regression analysis adjusted for clinically important baseline variables and doses of ACEIs/ARBs and BBs demonstrated resting HR ≤65 bpm as an independent predictor of improved survival compared to resting HR >65 bpm (HR 0.3, 95%CI 0.1-0.7, P 0.005). In octogenarians with HFrEF and concomitant AF, lowering resting HR to levels as low as HR ≤65 bpm was still associated with improved survival from all-cause mortality. Our data indicate that mortality in AF became comparable to SR when patients were on maximally up-titrated beta-blocker doses with HR as low as 75 bpm.

  8. Impact of Dose on Local Failure Rates After Image-Guided Reirradiation of Recurrent Paraspinal Metastases

    SciTech Connect

    Damast, Shari; Wright, Jean; Bilsky, Mark; Hsu, Meier; Zhang Zhigang; Lovelock, Michael; Cox, Brett; Zatcky, Joan; Yamada, Yoshiya

    2011-11-01

    Purpose: To examine the impact of dose on local failure (LF) rates in the re-treatment of recurrent paraspinal metastases with image-guided intensity-modulated radiotherapy (IG-IMRT). Methods and Materials: The records of patients with in-field recurrence after previous spine radiation (median dose, 30 Gy) who received salvage IG-IMRT with either five 4-Gy (20-Gy group, n = 42) or five 6-Gy (30-Gy group, n = 55) daily fractions between January 2003 and August 2008 were reviewed. Institutional practice was 20 Gy before April 2006, when it changed to 30 Gy. A total of 47 cases (48%) were treated adjuvantly, after surgery to decompress epidural disease. LF after IG-IMRT was defined radiographically. Results: The median follow-up was 12.1 months (range, 0.2-63.6 months). The 1-year cumulative incidences of LF after 20 Gy and 30 Gy IG-IMRT were 45% and 26%, respectively (p = 0.04). Of all treatment characteristics examined (20-Gy vs. 30-Gy dose group, dose to 95% of the planned and gross target volume, tumor size, histology, receipt of surgery, and interval between first and second radiation), only dose group had a significant impact on actuarial LF incidence (p = 0.04; unadjusted HR, 0.51; 95% CI, 0.27-0.96). There was no incidence of myelopathy. Conclusions: A significant decrease in LF after IG-IMRT with five 6-Gy fractions compared with five 4-Gy fractions was observed without increased risk of myelopathy. Until prospective data comparing stereotactic hypofractionated and single-fraction regimens become available, when reirradiating recurrent paraspinal metastases with IG-IMRT, administration of five 6-Gy daily fractions is reasonable.

  9. Cryogenic Treatment of Production Components in High-Wear Rate Wells

    SciTech Connect

    Milliken, M.

    2002-04-29

    Deep Cryogenic Tempering (DCT) is a specialized process whereby the molecular structure of a material is ''re-trained'' through cooling to -300 F and then heating to +175-1100 F. Cryocon, Inc. (hereafter referred to as Cryocon) and RMOTC entered an agreement to test the process on oilfield production components, including rod pumps, rods, couplings, and tubing. Three Shannon Formation wells were selected (TD about 500 ft) based on their proclivity for high component wear rates. Phase 1 of the test involved operation for a nominal 120 calendar day period with standard, non-treated components. In Phase 2, treated components were installed and operated for another nominal 120 calendar day period. Different cryogenic treatment profiles were used for components in each well. Rod pumps (two treated and one untreated) were not changed between test phases. One well was operated in pumped-off condition, resulting in abnormal wear and disqualification from the test. Testing shows that cryogenic treatment reduced wear of rods, couplers, and pump barrels. Testing of production tubing produced mixed results.

  10. Convergence of strain energy release rate components for edge-delaminated composite laminates

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Crews, J. H., Jr.; Aminpour, M. A.

    1987-01-01

    Strain energy release rates for edge delaminated composite laminates were obtained using quasi 3 dimensional finite element analysis. The problem of edge delamination at the -35/90 interfaces of an 8-ply composite laminate subjected to uniform axial strain was studied. The individual components of the strain energy release rates did not show convergence as the delamination tip elements were made smaller. In contrast, the total strain energy release rate converged and remained unchanged as the delamination tip elements were made smaller and agreed with that calculated using a classical laminated plate theory. The studies of the near field solutions for a delamination at an interface between two dissimilar isotropic or orthotropic plates showed that the imaginary part of the singularity is the cause of the nonconvergent behavior of the individual components. To evaluate the accuracy of the results, an 8-ply laminate with the delamination modeled in a thin resin layer, that exists between the -35 and 90 plies, was analyzed. Because the delamination exists in a homogeneous isotropic material, the oscillatory component of the singularity vanishes.

  11. Convergence of strain energy release rate components for edge-delaminated composite laminates

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Crews, J. H., Jr.; Aminpour, M. A.

    1988-01-01

    Strain energy release rates for edge delaminated composite laminates were obtained using quasi 3 dimensional finite element analysis. The problem of edge delamination at the -35/90 interfaces of an 8-ply composite laminate subjected to uniform axial strain was studied. The individual components of the strain energy release rates did not show convergence as the delamination tip elements were made smaller. In contrast, the total strain energy release rate converged and remained unchanged as the delamination tip elements were made smaller and agreed with that calculated using a classical laminated plate theory. The studies of the near field solutions for a delamination at an interface between two dissimilar isotropic or orthotropic plates showed that the imaginary part of the singularity is the cause of the nonconvergent behavior of the individual components. To evaluate the accuracy of the results, an 8-ply laminate with the delamination modeled in a thin resin layer, that exists between the -35 and 90 plies, was analyzed. Because the delamination exists in a homogeneous isotropic material, the oscillatory component of the singularity vanishes.

  12. L-arginine reduces heart rate and improves hemodynamics in severe congestive heart failure.

    PubMed

    Bocchi, E A; Vilella de Moraes, A V; Esteves-Filho, A; Bacal, F; Auler, J O; Carmona, M J; Bellotti, G; Ramires, A F

    2000-03-01

    Stimulated endothelium-derived relaxing factor-mediated vasodilation and conduit artery distensibility are impaired in congestive heart failure (CHF). L-arginine could have a potentially beneficial role in CHF, acting through the nitric oxide (NO)-L-arginine pathway or by growth hormone increment. This study was undertaken to investigate the effects of L-arginine on heart rate, hemodynamics, and left ventricular (LV) function in CHF. In seven patients (aged 39 +/- 8 years) with CHF, we obtained the following parameters using echocardiography and an LV Millar Mikro-Tip catheter simultaneously under four conditions: basal, during NO inhalation (40 ppm), in basal condition before L-arginine infusion, and after L-arginine intravenous infusion (mean dose 30.4 +/- 1.9 g). Nitric oxide inhalation increased pulmonary capillary wedge pressure from 25 +/- 9 to 31 +/- 7 mmHg (p < 0.05), but did not change echocardiographic variables or LV contractility by elastance determination. L-arginine decreased heart rate (from 88 +/- 15 to 80 +/- 16 beats/min, p<0.005), mean systemic arterial pressure (from 84 +/- 17 to 70 +/- 18 mmHg, p < 0.007), and systemic vascular resistance (from 24 +/- 8 to 15 +/- 6 Wood units, p<0.003). L-arginine increased right atrial pressure (from 7 +/- 2 to 10 +/- 3 mmHg, p<0.04), cardiac output (from 3.4 +/- 0.7 to 4.1 +/- 0.8 l/min, p < 0.009), and stroke volume (from 40 +/- 9 to 54 +/- 14 ml, p < 0.008). The ratios of pulmonary vascular resistance to systemic vascular resistance at baseline and during NO inhalation were 0.09 and 0.075, respectively, and with L-arginine this increased from 0.09 to 0.12. L-arginine exerted no effect on contractility; however, by acting on systemic vascular resistance it improved cardiac performance. L-arginine showed a negative chronotropic effect. The possible beneficial effect of L-arginine on reversing endothelial dysfunction in CHF without changing LV contractility should be the subject of further investigations.

  13. Uncemented porous tantalum acetabular components: early follow-up and failures in 613 primary total hip arthroplasties.

    PubMed

    Noiseux, Nicolas O; Long, William J; Mabry, Tad M; Hanssen, Arlen D; Lewallen, David G

    2014-03-01

    Uncemented tantalum acetabular components were introduced in 1997. The purpose was to determine the 2- to 10-year results with this implant material in primary total hip arthroplasty. Our registry identified all primary total hip cases with porous tantalum cups implanted from 1997 to 2004. Clinical outcomes and radiographs were studied. 613 cases were identified. Seventeen percent of patients were lost to follow-up. Twenty-five reoperations were performed (4.4%). Acetabular cup removal occurred in 6 cases (1.2%). No cups were revised for aseptic loosening. Incomplete radiolucent lines were found on 9.3% of initial postoperative radiographs. At 2 years, 67% had resolved. Zero new radiolucent lines were detected. Two- to 10-year results of porous tantalum acetabular components for primary total hip arthroplasty demonstrate high rates of initial stability and apparent ingrowth. © 2014.

  14. Components of the cannabinoid system in the dorsal periaqueductal gray are related to resting heart rate

    PubMed Central

    Dean, Caron; Hillard, Cecilia J.; Seagard, Jeanne L.; Hopp, Francis A.; Hogan, Quinn H.

    2016-01-01

    The present study was undertaken to examine whether variations in endocannabinoid signaling in the dorsal periaqueductal gray (dPAG) are associated with baseline autonomic nerve activity, heart rate, and blood pressure. Blood pressure was recorded telemetrically in rats, and heart rate and power spectral analysis of heart rate variability were determined. Natural variations from animal to animal provided a range of baseline values for analysis. Transcript levels of endocannabinoid signaling components in the dPAG were analyzed, and endocannabinoid content and catabolic enzyme activity were measured. Higher baseline heart rate was associated with increased anandamide content and with decreased activity of the anandamide-hydrolyzing enzyme and fatty acid amide hydrolase (FAAH), and it was negatively correlated with transcript levels of both FAAH and monoacylglycerol lipase (MAGL), a catabolic enzyme for 2-arachidonoylglycerol (2-AG). Autonomic tone and heart rate, but not blood pressure, were correlated to levels of FAAH mRNA. In accordance with these data, exogenous anandamide in the dPAG of anesthetized rats increased heart rate. These data indicate that in the dPAG, anandamide, a FAAH-regulated lipid, contributes to regulation of baseline heart rate through influences on autonomic outflow. PMID:27280429

  15. Dynamics of excitatory synaptic components in sustained firing at low rates.

    PubMed

    Wyart, Claire; Cocco, Simona; Bourdieu, Laurent; Léger, Jean-Francois; Herr, Catherine; Chatenay, Didier

    2005-06-01

    Sustained firing is necessary for the persistent activity associated with working memory. The relative contributions of the reverberation of excitation and of the temporal dynamics of the excitatory postsynaptic potential (EPSP) to the maintenance of activity are difficult to evaluate in classical preparations. We used simplified models of synchronous excitatory networks, hippocampal autapses and pairs, to study the synaptic mechanisms underlying firing at low rates. Calcium imaging and cell attached recordings showed that these neurons spontaneously fired bursts of action potentials that lasted for seconds over a wide range of frequencies. In 2-wk-old cells, the median firing frequency was low (11 +/- 8.8 Hz), whereas in 3- to 4-wk-old cells, it decreased to a very low value (2 +/- 1.3 Hz). In both cases, we have shown that the slowest synaptic component supported firing. In 2-wk-old autapses, antagonists of N-methyl-d-aspartate receptors (NMDARs) induced rare isolated spikes showing that the NMDA component of the EPSP was essential for bursts at low frequency. In 3- to 4-wk-old neurons, the very low frequency firing was maintained without the NMDAR activation. However EGTA-AM or alpha-methyl-4-carboxyphenylglycine (MCPG) removed the very slow depolarizing component of the EPSP and prevented the sustained firing at very low rate. A metabotropic glutamate receptor (mGluR)-activated calcium sensitive conductance is therefore responsible for a very slow synaptic component associated with firing at very low rate. In addition, our observations suggested that the asynchronous release of glutamate might participate also in the recurring bursting.

  16. The second Sandia Fracture Challenge. Predictions of ductile failure under quasi-static and moderate-rate dynamic loading

    DOE PAGES

    Boyce, B. L.; Kramer, S. L. B.; Bosiljevac, T. R.; ...

    2016-03-14

    Ductile failure of structural metals is relevant to a wide range of engineering scenarios. Computational methods are employed to anticipate the critical conditions of failure, yet they sometimes provide inaccurate and misleading predictions. Challenge scenarios, such as the one presented in the current work, provide an opportunity to assess the blind, quantitative predictive ability of simulation methods against a previously unseen failure problem. Instead of evaluating the predictions of a single simulation approach, the Sandia Fracture Challenge relied on numerous volunteer teams with expertise in computational mechanics to apply a broad range of computational methods, numerical algorithms, and constitutive modelsmore » to the challenge. This exercise is intended to evaluate the state of health of technologies available for failure prediction. In the first Sandia Fracture Challenge, a wide range of issues were raised in ductile failure modeling, including a lack of consistency in failure models, the importance of shear calibration data, and difficulties in quantifying the uncertainty of prediction [see Boyce et al. (Int J Fract 186:5–68, 2014) for details of these observations]. This second Sandia Fracture Challenge investigated the ductile rupture of a Ti–6Al–4V sheet under both quasi-static and modest-rate dynamic loading (failure in ~ 0.1 s). Like the previous challenge, the sheet had an unusual arrangement of notches and holes that added geometric complexity and fostered a competition between tensile- and shear-dominated failure modes. The teams were asked to predict the fracture path and quantitative far-field failure metrics such as the peak force and displacement to cause crack initiation. Fourteen teams contributed blind predictions, and the experimental outcomes were quantified in three independent test labs. In addition, shortcomings were revealed in this second challenge such as inconsistency in the application of appropriate boundary

  17. The second Sandia Fracture Challenge. Predictions of ductile failure under quasi-static and moderate-rate dynamic loading

    SciTech Connect

    Boyce, B. L.; Kramer, S. L. B.; Bosiljevac, T. R.; Corona, E.; Moore, J. A.; Elkhodary, K.; Simha, C. H. M.; Williams, B. W.; Cerrone, A. R.; Nonn, A.; Hochhalter, J. D.; Bomarito, G. F.; Warner, J. E.; Carter, B. J.; Warner, D. H.; Ingraffea, A. R.; Zhang, T.; Fang, X.; Lua, J.; Chiaruttini, V.; Mazière, M.; Feld-Payet, S.; Yastrebov, V. A.; Besson, J.; Chaboche, J. -L.; Lian, J.; Di, Y.; Wu, B.; Novokshanov, D.; Vajragupta, N.; Kucharczyk, P.; Brinnel, V.; Döbereiner, B.; Münstermann, S.; Neilsen, M. K.; Dion, K.; Karlson, K. N.; Foulk, J. W.; Brown, A. A.; Veilleux, M. G.; Bignell, J. L.; Sanborn, S. E.; Jones, C. A.; Mattie, P. D.; Pack, K.; Wierzbicki, T.; Chi, S. -W.; Lin, S. -P.; Mahdavi, A.; Predan, J.; Zadravec, J.; Gross, A. J.; Ravi-Chandar, K.; Xue, L.

    2016-03-14

    Ductile failure of structural metals is relevant to a wide range of engineering scenarios. Computational methods are employed to anticipate the critical conditions of failure, yet they sometimes provide inaccurate and misleading predictions. Challenge scenarios, such as the one presented in the current work, provide an opportunity to assess the blind, quantitative predictive ability of simulation methods against a previously unseen failure problem. Instead of evaluating the predictions of a single simulation approach, the Sandia Fracture Challenge relied on numerous volunteer teams with expertise in computational mechanics to apply a broad range of computational methods, numerical algorithms, and constitutive models to the challenge. This exercise is intended to evaluate the state of health of technologies available for failure prediction. In the first Sandia Fracture Challenge, a wide range of issues were raised in ductile failure modeling, including a lack of consistency in failure models, the importance of shear calibration data, and difficulties in quantifying the uncertainty of prediction [see Boyce et al. (Int J Fract 186:5–68, 2014) for details of these observations]. This second Sandia Fracture Challenge investigated the ductile rupture of a Ti–6Al–4V sheet under both quasi-static and modest-rate dynamic loading (failure in ~ 0.1 s). Like the previous challenge, the sheet had an unusual arrangement of notches and holes that added geometric complexity and fostered a competition between tensile- and shear-dominated failure modes. The teams were asked to predict the fracture path and quantitative far-field failure metrics such as the peak force and displacement to cause crack initiation. Fourteen teams contributed blind predictions, and the experimental outcomes were quantified in three independent test labs. In addition, shortcomings were revealed in this second challenge such as inconsistency in the application of appropriate boundary conditions, need

  18. Effects of walking on heart rate recovery, endothelium modulators and quality of life in patients with heart failure.

    PubMed

    Tsarouhas, Konstantinos; Karatzaferi, Christina; Tsitsimpikou, Christina; Haliassos, Alexander; Kouretas, Demetrios; Pavlidis, Pavlos; Veskoukis, Aristidis; Adamopoulos, Stamatis; Kyriakides, Zenon; Constantinou, Louis; Koutedakis, Yannis; Rentoukas, Elias

    2011-08-01

    Few studies have addressed the impact of moderate unsupervised everyday physical activity in patients with chronic heart failure (CHF). We investigated the effects of a 12-week walking programme as the sole exercise intervention on heart rate recovery (HRR), index of the autonomic system equilibrium, serum modulators of endothelial function (i.e. asymmetric dimethylarginine (ADMA) and homocysteine), markers of inflammation and oxidative stress and quality of life measures (i.e. SF-36 and the Zung depression scale) in CHF patients. Twenty-eight stabilized CHF patients of ΝYHΑ class II and III volunteered to participate either in the exercise (n = 18) or in the non-exercise (n = 10) groups. Ten age-matched healthy volunteers provided reference values. The exercise programme consisted of unsupervised 40-minute walking for five days per week. Repeated measures ANOVA revealed significant improvements in HRR (p < 0.001) in the exercise patients compared to their non-exercise counterparts. ADMA levels in CHF patients at baseline were found higher than the healthy reference volunteers (p < 0.03), while a decrease in ADMA levels after walking was associated with HRR changes (r = 0.74, p = 0.007). Homocysteine levels both at baseline and at the end of the walking intervention decreased in the exercise group, but were still higher than in the healthy individuals. Average walking distance positively correlated with homocysteine decrease (p < 0.05). Total SF-36 score significantly improved (p < 0.02) mainly due to enhancements in the physical component score (p < 0.026). A 12-week unsupervised walking programme exhibits a pronounced HRR amelioration, possibly attenuates endothelial damage and induces a concomitant improvement in perceived quality of life in CHF patients.

  19. Comparison of compact bone failure under two different loading rates: experimental and modelling approaches.

    PubMed

    Pithioux, M; Subit, D; Chabrand, P

    2004-10-01

    Understanding the mechanical behaviour of bones up to failure is necessary for diagnosis and prevention of accident and trauma. As far as we know, no authors have yet studied the tensile behaviour of compact bone including failure under dynamic loadings (1 m/s). The originality of this study comes from not only the analysis of compact bone failure under dynamic loadings, the results of which are compared to those obtained under quasi-static loadings, but also the development of a statistical model. We developed a protocol using three different devices. Firstly, an X-ray scanner to analyse bone density, secondly, a common tensile device to perform quasi-static experiments, and thirdly, a special device based upon a hydraulic cylinder to perform dynamic tests. For all the tests, we used the same sample shape which took into account the brittleness of the compact bone. We first performed relaxation and hysteresis tests followed by tensile tests up to failure. Viscous and plastic effects were not relevant to the compact bone behaviour so its behaviour was considered elastic and brittle. The bovine compact bone was three to four times more brittle under a dynamic load than under a quasi-static one. Numerically, a statistical model, based upon the Weibull theory, is used to predict the failure stress in compact bone.

  20. Removing the thermal component from heart rate provides an accurate VO2 estimation in forest work.

    PubMed

    Dubé, Philippe-Antoine; Imbeau, Daniel; Dubeau, Denise; Lebel, Luc; Kolus, Ahmet

    2016-05-01

    Heart rate (HR) was monitored continuously in 41 forest workers performing brushcutting or tree planting work. 10-min seated rest periods were imposed during the workday to estimate the HR thermal component (ΔHRT) per Vogt et al. (1970, 1973). VO2 was measured using a portable gas analyzer during a morning submaximal step-test conducted at the work site, during a work bout over the course of the day (range: 9-74 min), and during an ensuing 10-min rest pause taken at the worksite. The VO2 estimated, from measured HR and from corrected HR (thermal component removed), were compared to VO2 measured during work and rest. Varied levels of HR thermal component (ΔHRTavg range: 0-38 bpm) originating from a wide range of ambient thermal conditions, thermal clothing insulation worn, and physical load exerted during work were observed. Using raw HR significantly overestimated measured work VO2 by 30% on average (range: 1%-64%). 74% of VO2 prediction error variance was explained by the HR thermal component. VO2 estimated from corrected HR, was not statistically different from measured VO2. Work VO2 can be estimated accurately in the presence of thermal stress using Vogt et al.'s method, which can be implemented easily by the practitioner with inexpensive instruments.

  1. [Research on ultrafine grinding technology of improving dissolution rates of effective components in Sanjie Zhentong capsule].

    PubMed

    Xu, Zhong-kun; Gao, Jin; Qin, Jian-ping; Chen, Guang-bo; Wang, Zhen-zhong; Xiao, Wei

    2015-05-01

    The effects of ultrafine grinding on the dissolution rates of the effective components in Sanjie Zhentong capsule (SZC) were studied in this experiment. Fine and ultrafine powder of SZC intermediates were made by ordinary grinding and ultrafine grinding technology, and then granulated by wet granulation. SZC were prepared by fine powder, ultrafine powder and ultrafine granules, respectively. With resveratrol and loureirin B as investigated indexes, dissolution rates of the four intermediates in SZC were determined by cup method and HPLC. The dissolution rates of resveratrol in SZC prepared by fine powder, ultrafine powder and ultrafine granules were 26.11%, 63.27%, 67.49%, respectively; and the dissolution rates of loureirin B were 7.160%, 20.29%, 23.05%, respectively. The dissolution rate of resveratrol and loureirin B in SZC prepared by ultrafine granules was the best. D90 size of ultrafine grinding was 13.221 μm and could improve the dissolution rates of resveratrol and loureirin B in SZC.

  2. Microcracking damage and the fracture process in relation to strain rate in human cortical bone tensile failure.

    PubMed

    Zioupos, Peter; Hansen, Ulrich; Currey, John D

    2008-10-20

    It is difficult to define the 'physiological' mechanical properties of bone. Traumatic failures in-vivo are more likely to be orders of magnitude faster than the quasistatic tests usually employed in-vitro. We have reported recently [Hansen, U., Zioupos, P., Simpson, R., Currey, J.D., Hynd, D., 2008. The effect of strain rate on the mechanical properties of human cortical bone. Journal of Biomechanical Engineering/Transactions of the ASME 130, 011011-1-8] results from tests on specimens of human femoral cortical bone loaded in tension at strain rates (epsilon ) ranging from low (0.08s(-1)) to high (18s(-1)). Across this strain rate range the modulus of elasticity generally increased, stress at yield and failure and strain at failure decreased for rates higher than 1s(-1), while strain at yield was invariant for most strain rates and only decreased at rates higher than 10s(-1). The results showed that strain rate has a stronger effect on post-yield deformation than on initiation of macroscopic yielding. In general, specimens loaded at high strain rates were brittle, while those loaded at low strain rates were much tougher. Here, a post-test examination of the microcracking damage reveals that microcracking was inversely related to the strain rate. Specimens loaded at low strain rates showed considerable post-yield strain and also much more microcracking. Partial correlation and regression analysis suggested that the development of post-yield strain was a function of the amount of microcracking incurred (the cause), rather than being a direct result of the strain rate (the excitation). Presumably low strain rates allow time for microcracking to develop, which increases the compliance of the specimen, making them tougher. This behaviour confirms a more general rule that the degree to which bone is brittle or tough depends on the amount of microcracking damage it is able to sustain. More importantly, the key to bone toughness is its ability to avoid a ductile

  3. Effect of a telemonitoring-facilitated collaboration between general practitioner and heart failure clinic on mortality and rehospitalization rates in severe heart failure: the TEMA-HF 1 (TElemonitoring in the MAnagement of Heart Failure) study.

    PubMed

    Dendale, Paul; De Keulenaer, Gilles; Troisfontaines, Pierre; Weytjens, Caroline; Mullens, Wilfried; Elegeert, Ivan; Ector, Bavo; Houbrechts, Marita; Willekens, Koen; Hansen, Dominique

    2012-03-01

    Chronic heart failure (CHF) patients are frequently rehospitalized within 6 months after an episode of fluid retention. Rehospitalizations are preventable, but this requires an extensive organization of the healthcare system. In this study, we tested whether intensive follow-up of patients through a telemonitoring-facilitated collaboration between general practitioners (GPs) and a heart failure clinic could reduce mortality and rehospitalization rate. One hunderd and sixty CHF patients [mean age 76 ± 10 years, 104 males, mean left ventricular ejection fraction (LVEF) 35 ± 15%] were block randomized by sealed envelopes and assigned to 6 months of intense follow-up facilitated by telemonitoring (TM) or usual care (UC). The TM group measured body weight, blood pressure, and heart rate on a daily basis with electronic devices that transferred the data automatically to an online database. Email alerts were sent to the GP and heart failure clinic to intervene when pre-defined limits were exceeded. All-cause mortality was significantly lower in the TM group as compared with the UC group (5% vs. 17.5%, P = 0.01). The total number of follow-up days lost to hospitalization, dialysis, or death was significantly lower in the TM group as compared with the UC group (13 vs. 30 days, P = 0.02). The number of hospitalizations for heart failure per patient showed a trend (0.24 vs. 0.42 hospitalizations/patient, P = 0.06) in favour of TM. Telemonitoring-facilitated collaboration between GPs and a heart failure clinic reduces mortality and number of days lost to hospitalization, death, or dialysis in CHF patients. These findings need confirmation in a large trial.

  4. Verification of International Space Station Component Leak Rates by Helium Accumulation Method

    NASA Technical Reports Server (NTRS)

    Underwood, Steve D.; Smith, Sherry L.

    2003-01-01

    Discovery of leakage on several International Space Station U.S. Laboratory Module ammonia system quick disconnects (QDs) led to the need for a process to quantify total leakage without removing the QDs from the system. An innovative solution was proposed allowing quantitative leak rate measurement at ambient external pressure without QD removal. The method utilizes a helium mass spectrometer configured in the detector probe mode to determine helium leak rates inside a containment hood installed on the test component. The method was validated through extensive developmental testing. Test results showed the method was viable, accurate and repeatable for a wide range of leak rates. The accumulation method has been accepted by NASA and is currently being used by Boeing Huntsville, Boeing Kennedy Space Center and Boeing Johnson Space Center to test welds and valves and will be used by Alenia to test the Cupola. The method has been used in place of more expensive vacuum chamber testing which requires removing the test component from the system.

  5. RBANS embedded measures of suboptimal effort in dementia: effort scale has a lower failure rate than the effort index.

    PubMed

    Burton, Rachel L; Enright, Joe; O'Connell, Megan E; Lanting, Shawnda; Morgan, Debra

    2015-02-01

    The importance of evaluating effort in neuropsychological assessments has been widely acknowledged, but measuring effort in the context of dementia remains challenging due to the impact of dementia severity on effort measure scores. Two embedded measures have been developed for the repeatable battery for the assessment of neuropsychological status (RBANS; Randolph, C., Tierney, M. C., Mohr, E., & Chase, T. N. (1998). The repeatable battery for the assessment of neuropsychological status (RBANS): Preliminary clinical validity. Journal of Clinical and Experimental Neuropsychology, 20 (3), 310-319): the Effort Index (EI; Silverberg, N. D., Wertheimer, J. C., & Fichtenberg, N. L. (2007). An effort index for the repeatable battery for the assessment of neuropsychological status (RBANS). Clinical Neuropsychologist, 21 (5), 841-854) and the Effort Scale (ES; Novitski, J., Steele, S., Karantzoulis, S., & Randolph, C. (2012). The repeatable battery for the assessment of neuropsychological status effort scale. Archives of Clinical Neuropsychology, 27 (2), 190-195). We explored failure rates on these effort measures in a non-litigating mixed dementia sample (N = 145). Failure rate on the EI was high (48%) and associated with dementia severity. In contrast, failure on the ES was 14% but differed based on type of dementia. ES failure was low (4%) when dementia was due to Alzheimer disease (AD), but high (31%) for non-AD dementias. These data raise concerns about use of the RBANS embedded effort measures in dementia evaluations.

  6. Effect of pimobendan on case fatality rate in Doberman Pinschers with congestive heart failure caused by dilated cardiomyopathy.

    PubMed

    O'Grady, M R; Minors, S L; O'Sullivan, M L; Horne, R

    2008-01-01

    Despite traditional therapy of a diuretic, angiotensin converting enzyme inhibitor, digoxin, or a combination of these drugs, survival of dogs with dilated cardiomyopathy (DCM) is low. Pimobendan, an inodilator, has both inotropic and balanced peripheral vasodilatory properties. Pimobendan when added to conventional therapy will improve morbidity and reduce case fatality rate in Doberman Pinschers with congestive heart failure (CHF) caused by DCM. Sixteen Doberman Pinschers in CHF caused by DCM. A prospective randomized, double-blind, placebo-controlled study with treatment failure as the primary and quality of life (QoL) indices as secondary outcome variables. Therapy consisted of furosemide (per os [PO] as required) and benazepril hydrochloride (0.5 mg/kg PO q12h) and dogs were randomized in pairs and by sex to receive pimobendan (0.25 mg/kg PO q12h) or placebo (1 tablet PO q12h). Pimobendan-treated dogs had a significant improvement in time to treatment failure (pimobendan median, 130.5 days; placebo median, 14 days; P= .002; risk ratio = 0.35, P= .003, lower 5% confidence limit = 0.13, upper 95% confidence limit = 0.71). Number and rate of dogs reaching treatment failure in the placebo group precluded the analysis of QoL. Pimobendan should be used as a first-line therapeutic in Doberman Pinschers for the treatment of CHF caused by DCM.

  7. Remnant growth rate after portal vein embolization is a good early predictor of post-hepatectomy liver failure.

    PubMed

    Leung, Universe; Simpson, Amber L; Araujo, Raphael L C; Gönen, Mithat; McAuliffe, Conor; Miga, Michael I; Parada, E Patricia; Allen, Peter J; D'Angelica, Michael I; Kingham, T Peter; DeMatteo, Ronald P; Fong, Yuman; Jarnagin, William R

    2014-10-01

    After portal vein embolization (PVE), the future liver remnant (FLR) hypertrophies for several weeks. An early marker that predicts a low risk of post-hepatectomy liver failure can reduce the delay to surgery. Liver volumes of 153 patients who underwent a major hepatectomy (>3 segments) after PVE for primary or secondary liver malignancy between September 1999 and November 2012 were retrospectively evaluated with computerized volumetry. Pre- and post-PVE FLR volume and functional liver volume were measured. Degree of hypertrophy (DH = post-FLR/post-functional liver volume - pre-FLR/pre-functional liver volume) and growth rate (GR = DH/weeks since PVE) were calculated. Postoperative complications and liver failure were correlated with DH, measured GR, and estimated GR derived from a formula based on body surface area. Eligible patients underwent 93 right hepatectomies, 51 extended right hepatectomies, 4 left hepatectomies, and 5 extended left hepatectomies. Major complications occurred in 44 patients (28.7%) and liver failure in 6 patients (3.9%). Nonparametric regression showed that post-embolization FLR percent correlated poorly with liver failure. Receiver operating characteristic curves showed that DH and GR were good predictors of liver failure (area under the curve [AUC] = 0.80; p = 0.011 and AUC = 0.79; p = 0.015) and modest predictors of major complications (AUC = 0.66; p = 0.002 and AUC = 0.61; p = 0.032). No patient with GR >2.66% per week had liver failure develop. The predictive value of measured GR was superior to estimated GR for liver failure (AUC = 0.79 vs 0.58; p = 0.046). Both DH and GR after PVE are strong predictors of post-hepatectomy liver failure. Growth rate might be a better guide for the optimum timing of liver resection than static volumetric measurements. Measured volumetrics correlated with outcomes better than estimated volumetrics. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  8. Phylogenetic, functional, and structural components of variation in bone growth rate of amniotes.

    PubMed

    Cubo, Jorge; Legendre, Pierre; de Ricqlès, Armand; Montes, Laëtitia; de Margerie, Emmanuel; Castanet, Jacques; Desdevises, Yves

    2008-01-01

    The biological features observed in every living organism are the outcome of three sets of factors: historical (inherited by homology), functional (biological adaptation), and structural (properties inherent to the materials with which organs are constructed, and the morphogenetic rules by which they grow). Integrating them should bring satisfactory causal explanations of empirical data. However, little progress has been accomplished in practice toward this goal, because a methodologically efficient tool was lacking. Here we use a new statistical method of variation partitioning to analyze bone growth in amniotes. (1) Historical component. The variation of bone growth rates contains a significant phylogenetic signal, suggesting that the observed patterns are partly the outcome of shared ancestry. (2) Functional causation. High growth rates, although energy costly, may be adaptive (i.e., they may increase survival rates) in taxa showing short growth periods (e.g., birds). In ectothermic amniotes, low resting metabolic rates may limit the maximum possible growth rates. (3) Structural constraint. Whereas soft tissues grow through a multiplicative process, growth of mineralized tissues is accretionary (additive, i.e., mineralization fronts occur only at free surfaces). Bone growth of many amniotes partially circumvents this constraint: it is achieved not only at the external surface of the bone shaft, but also within cavities included in the bone cortex as it grows centrifugally. Our approach contributes to the unification of historicism, functionalism, and structuralism toward a more integrated evolutionary biology.

  9. Estimation of variance components and genetic trends for twinning rate in Holstein dairy cattle of Iran.

    PubMed

    Ghavi Hossein-Zadeh, N; Nejati-Javaremi, A; Miraei-Ashtiani, S R; Kohram, H

    2009-07-01

    Calving records from the Animal Breeding Center of Iran, collected from January 1991 to December 2007 and comprising 1,163,594 Holstein calving events from 2,552 herds, were analyzed using a linear animal model, linear sire model, threshold animal model, and threshold sire model to estimate variance components, heritabilities, genetic correlations, and genetic trends for twinning rate in the first, second, and third parities. The overall twinning rate was 3.01%. Mean incidence of twins increased from first to fourth and later parities: 1.10, 3.20, 4.22, and 4.50%, respectively. For first-parity cows, a maximum frequency of twinning was observed from January through April (1.36%), and second- and third-parity cows showed peaks from July to September (at 3.35 and 4.55%, respectively). The phenotypic rate of twinning decreased from 1991 to 2007 for the first, second, and third parities. Sire predicted transmitting abilities were estimated using linear sire model and threshold sire model analyses. Sire transmitting abilities for twinning rate in the first, second, and third parities ranged from -0.30 to 0.42, -0.32 to 0.31, and -0.27 to 0.30, respectively. Heritability estimates of twinning rate for parities 1, 2, and 3 ranged from 1.66 to 10.6%, 1.35 to 9.0%, and 1.10 to 7.3%, respectively, using different models for analysis. Heritability estimates for twinning rate, obtained from the analysis of threshold models, were greater than the estimates of linear models. Solutions for age at calving for the first, second, and third parities demonstrated that cows older at calving were more likely to have twins. Genetic correlations for twinning rate between parities 2 and 3 were greater than correlations between parities 1 and 2 and between parities 1 and 3. There was a slightly increasing trend for twinning rate in parities 1, 2, and 3 over time with the analysis of linear animal and linear sire models, but the trend for twinning rate in parities 1, 2, and 3 with threshold

  10. Highly sensitive radon monitor and radon emanation rates for detector components

    NASA Astrophysics Data System (ADS)

    Choi, E.; Komori, M.; Takahisa, K.; Kudomi, N.; Kume, K.; Hayashi, K.; Yoshida, S.; Ohsumi, H.; Ejiri, H.; Kishimoto, T.; Matsuoka, K.; Tasaka, S.

    2001-02-01

    The radon emanation rates for materials were measured by using the electrostatic precipitation method as a radon monitor. It was found that a low level of radon was emanated from several material components in ELEGANT V. The radon monitor has been developed for the highly sensitive measurements of low-level radon concentration. The system was shown to have a sensitivity to radon concentrations as low as 1.6 mBq/ m3 for one day measurement. The system was also used as the radon concentration monitor for the gas inside the airtight box of the ELEGANT V at Oto Cosmo Observatory.

  11. Electrophysiological analyses of threshold conditions and rate-dependent failure of excitation in single myocytes from rabbit ventricle.

    PubMed

    Firek, L; Giles, W R

    1997-11-01

    The changes in transmembrane ionic currents that underlie normal excitability and rate-dependent failure were studied in single cells from rabbit ventricle by using whole cell voltage clamp methods. When trains of brief (1 to 2 ms) stimuli are applied at strengths very close to the threshold for excitation, a number of different patterns of action potential entrainment and failure are observed. In an individual cell, a characteristic pattern of entrainment or failure can be maintained for a relatively long time, allowing both a detailed description and a quantitative investigation of the ionic basis for this phenomenon. Three hypotheses for rate-dependent failure of excitation in rabbit ventricle were examined. The first is that following relatively high rates of stimulation, the intracellular calcium ion concentration increases and, secondarily, a background inwardly rectifying potassium ion current (IK1) decreases, thereby lowering the excitation threshold. The second hypothesis is that residual activation of the delayed rectifier potassium ion current (IK) causes the stimulus to become subthreshold as the rate of stimulation increases. The third hypothesis is that small changes in the time and voltage dependence of the inactivation and reactivation of the sodium ion current (INa) result in less net inward ion current for a given waveform of depolarization, and the cell therefore becomes inexcitable (eg, to every second stimulus). The calcium ion hypothesis was tested by buffering changes in intracellular calcium ion concentrations with BAPTA. The results strongly suggest that changes in intracellular calcium ion concentrations do not contribute significantly to the observed patterns of failure of excitation. The delayed rectifier hypothesis was evaluated using the class III antiarrhythmic drug dofetilide, which selectively blocks a large fraction of the IK current in rabbit ventricle. Dofetilide slightly decreased the stimulus threshold, suggesting that residual

  12. Pericranial muscular, respiratory, and heart rate components of the orienting response.

    PubMed

    Stekelenburg, J J; van Boxtel, A

    2002-11-01

    We have earlier found that voluntary attention to weak auditory stimuli induces inhibition of respiration, heart rate, and electromyographic (EMG) activity of masticatory and lower facial muscles and that these responses lower the auditory threshold for low-frequency sounds. In the current study, we examined whether this inhibitory response pattern also occurs during involuntary orienting to novel, nonsignal sounds. Environmental sounds of low intensity were presented unexpectedly during the performance of a reading task. Orienting responses (ORs) were elicited as indicated by heart rate deceleration and skin conductance responses. Inhibitory respiratory and pericranial EMG responses appeared to be intrinsic components of the OR. Together with the autonomic responses, they habituated when a nonsignal auditory stimulus was repeatedly presented. Our results also suggest that eye and pinna movements occurred toward the sound source. The results of the current study are consistent with the hypothesis of Sokolov (1963) that the primary function of the OR is enhancement of sensory sensitivity.

  13. Effect of suture selection on the rate of suture or mesh erosion and surgery failure in abdominal sacrocolpopexy.

    PubMed

    Shepherd, Jonathan P; Higdon, Homer Lee; Stanford, Edward J; Mattox, Thomas Fleming

    2010-07-01

    : To determine if suture type used for mesh attachment in abdominal sacrocolpopexy increases the rate of erosion/infection. : Two groups were temporally divided from June 1996 to May 2001 where braided permanent sutures (2-0 Ethibond, Ethicon, Somerville, New Jersey) were exclusively used for graft placement (n = 161) and from August 2001 to May 2006 where exclusively monofilament delayed absorbable (2-0 PDS, Ethicon) was used (n = 254). Data were analyzed for demographics, medical history, presenting/postoperative physical examination, concomitant surgeries, and complications. : Mesh/suture exposure rate was 3.7% (6/161) with Ethibond. There were no erosions with PDS (P = 0.002). Colpopexy failure was 1.7% (2/116) with Ethibond and 0% (0/235) with PDS (P = 0.11). : Delayed absorbable, monofilament suture appears to reduce the risk of graft/suture erosion without increasing surgical failure.

  14. Assessing the interaction of respiration and heart rate in heart failure and controls using ambulatory Holter recordings.

    PubMed

    Haigney, Mark; Zareba, Wojceich; La Rovere, Maria Teresa; Grasso, Ian; Mortara, David

    2014-01-01

    Breathing is a critical component of cardiopulmonary function, but few tools exist to evaluate respiration in ambulatory patients. Holter monitoring allows accurate diagnosis of a host of cardiac issues, and several investigators have demonstrated the ability to detect respiratory effort on the electrocardiogram. In this study we introduce a myogram signal derived from 12-lead, high frequency Holter as a means of detecting respiratory effort. Using the combined myogram and ECG signal, four novel variables were created: total number of Cheyne-Stokes episodes; the BWRatio, the ratio of power (above baseline) measured one second after peak-to-peak respiratory power, an assessment of the "shape" of the respiratory effort; DRR, the change in RR interval centering around peak inspiration; and minutes of synchronized breathing, a fixed ratio of heart beats to respiratory cycles. These variables were assessed in 24-hour recordings from three cohorts: healthy volunteers (n=33), heart failure subjects from the GISSI HF trial (n=383), and subjects receiving implantable defibrillators with severely depressed left ventricular function enrolled in the M2Risk trial (n=470). We observed a statistically significant 6-fold increase in the number of Cheyne-Stokes episodes (p=0.01 by ANOVA), decreases in BWRatio (p<0.001), as well as decrease in DRR in heart failure subjects; only minutes of synchronized breathing was not significantly decreased in heart failure. This study provides "proof of concept" that novel variables incorporating Holter-derived respiration can distinguish healthy subjects from heart failure. The utility of these variables for predicting heart failure, arrhythmia, and death risk in prospective studies needs to be assessed. Published by Elsevier Inc.

  15. Nonlinear analysis of heart rate variability within independent frequency components during the sleep-wake cycle.

    PubMed

    Vigo, Daniel E; Dominguez, Javier; Guinjoan, Salvador M; Scaramal, Mariano; Ruffa, Eduardo; Solernó, Juan; Siri, Leonardo Nicola; Cardinali, Daniel P

    2010-04-19

    Heart rate variability (HRV) is a complex signal that results from the contribution of different sources of oscillation related to the autonomic nervous system activity. Although linear analysis of HRV has been applied to sleep studies, the nonlinear dynamics of HRV underlying frequency components during sleep is less known. We conducted a study to evaluate nonlinear HRV within independent frequency components in wake status, slow-wave sleep (SWS, stages III or IV of non-rapid eye movement sleep), and rapid-eye-movement sleep (REM). The sample included 10 healthy adults. Polysomnography was performed to detect sleep stages. HRV was studied globally during each phase and then very low frequency (VLF), low frequency (LF) and high frequency (HF) components were separated by means of the wavelet transform algorithm. HRV nonlinear dynamics was estimated with sample entropy (SampEn). A higher SampEn was found when analyzing global variability (Wake: 1.53+/-0.28, SWS: 1.76+/-0.32, REM: 1.45+/-0.19, p=0.005) and VLF variability (Wake: 0.13+/-0.03, SWS: 0.19+/-0.03, REM: 0.14+/-0.03, p<0.001) at SWS. REM was similar to wake status regarding nonlinear HRV. We propose nonlinear HRV is a useful index of the autonomic activity that characterizes the different sleep-wake cycle stages.

  16. Radiographic failure and rates of re-operation after acromioclavicular joint reconstruction: a comparison of surgical techniques.

    PubMed

    Spencer, H T; Hsu, L; Sodl, J; Arianjam, A; Yian, E H

    2016-04-01

    To compare radiographic failure and re-operation rates of anatomical coracoclavicular (CC) ligament reconstructional techniques with non-anatomical techniques after chronic high grade acromioclavicular (AC) joint injuries. We reviewed chronic AC joint reconstructions within a region-wide healthcare system to identify surgical technique, complications, radiographic failure and re-operations. Procedures fell into four categories: (1) modified Weaver-Dunn, (2) allograft fixed through coracoid and clavicular tunnels, (3) allograft loop coracoclavicular fixation, and (4) combined allograft loop and synthetic cortical button fixation. Among 167 patients (mean age 38.1 years, (standard deviation (sd) 14.7) treated at least a four week interval after injury, 154 had post-operative radiographs available for analysis. Radiographic failure occurred in 33/154 cases (21.4%), with the lowest rate in Technique 4 (2/42 4.8%, p = 0.001). Half the failures occurred by six weeks, and the Kaplan-Meier survivorship at 24 months was 94.4% (95% confidence interval (CI) 79.6 to 98.6) for Technique 4 and 69.9% (95% CI 59.4 to 78.3) for the other techniques when combined. In multivariable survival analysis, Technique 4 had better survival than other techniques (Hazard Ratio 0.162, 95% CI 0.039 to 0.068, p = 0.013). Among 155 patients with a minimum of six months post-operative insurance coverage, re-operation occurred in 9.7% (15 patients). However, in multivariable logistic regression, Technique 4 did not reach a statistically significant lower risk for re-operation (odds ratio 0.254, 95% CI 0.05 to 1.3, p = 0.11). In this retrospective series, anatomical CC ligament reconstruction using combined synthetic cortical button and allograft loop fixation had the lowest rate of radiographic failure. Anatomical coracoclavicular ligament reconstruction using combined synthetic cortical button and allograft loop fixation had the lowest rate of radiographic failure. ©2016 The British Editorial

  17. Axonal and synaptic failure suppress the transfer of firing rate oscillations, synchrony and information during high frequency deep brain stimulation.

    PubMed

    Rosenbaum, Robert; Zimnik, Andrew; Zheng, Fang; Turner, Robert S; Alzheimer, Christian; Doiron, Brent; Rubin, Jonathan E

    2014-02-01

    High frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a widely used treatment for Parkinson's disease, but its effects on neural activity in basal ganglia circuits are not fully understood. DBS increases the excitation of STN efferents yet decouples STN spiking patterns from the spiking patterns of STN synaptic targets. We propose that this apparent paradox is resolved by recent studies showing an increased rate of axonal and synaptic failures in STN projections during DBS. To investigate this hypothesis, we combine in vitro and in vivo recordings to derive a computational model of axonal and synaptic failure during DBS. Our model shows that these failures induce a short term depression that suppresses the synaptic transfer of firing rate oscillations, synchrony and rate-coded information from STN to its synaptic targets. In particular, our computational model reproduces the widely reported suppression of parkinsonian β oscillations and synchrony during DBS. Our results support the idea that short term depression is a therapeutic mechanism of STN DBS that works as a functional lesion by decoupling the somatic spiking patterns of STN neurons from spiking activity in basal ganglia output nuclei.

  18. Acetylcholinesterase inhibition with pyridostigmine improves heart rate recovery after maximal exercise in patients with chronic heart failure

    PubMed Central

    Androne, A S; Hryniewicz, K; Goldsmith, R; Arwady, A; Katz, S D

    2003-01-01

    Objective: To characterise the effects of acetylcholinesterase inhibition with pyridostigmine on parasympathetic tone in patients with chronic heart failure (CHF). Design: Prospective randomised, double blind crossover trial. Setting: University hospital outpatient heart failure clinic. Patients: 20 ambulatory subjects with stable CHF (mean age 55 years, mean ejection fraction 24%). Interventions: Oral administration of a single dose of pyridostigmine 30 mg and matching placebo on separate days. Main outcome measures: Heart rate recovery at one minute and three minutes after completion of maximal exercise. Results: Heart rate recovery at one minute after exercise was significantly greater after administration of pyridostigmine than after administration of placebo (mean (SEM) 27.4 (3.2) beats/min v 22.4 (2.4) beats/min, p < 0.01). Heart rate recovery at three minutes after exercise did not differ after administration of pyridostigmine and placebo (mean (SEM) 44.4 (3.9) beats/min v 41.8 (3.6) beats/min, NS). Peak heart rate, peak oxygen uptake, peak respiratory exchange ratio, plasma noradrenaline (norepinephrine) concentrations, and plasma brain natriuretic peptide concentrations did not differ after administration of pyridostigmine and placebo. Conclusions: Acetylcholinesterase inhibition with pyridostigmine increased heart rate recovery at one minute but not at three minutes after exercise. A specific effect of pyridostigmine on heart rate one minute after exercise suggests that pyridostigmine augments parasympathetic tone in patients with CHF. PMID:12860856

  19. Does Biolox Delta ceramic reduce the rate of component fractures in total hip replacement?

    PubMed

    Massin, P; Lopes, R; Masson, B; Mainard, D

    2014-10-01

    Biolox Delta ceramic has been optimized with nano-sized, yttria-stabilized tetragonal zirconium and strontium oxide to help limit cracking propagation. Although its mechanical properties are better than those of earlier generation ceramics, existing data on this material are limited, thus the goals of this study were to determine: 1) the remaining rate of implant fracture; 2) the ideal combination of head diameter and component position. Hypothesis. We hypothesized that the use of the ceramic composite Biolox Delta had reduced the risk of implant fracture. Materials and methods. The bibliographic search (in Pubmed database with the key words «ceramic fracture» and «total hip prosthesis ») identified 46 articles on fractures in third or fourth generation ceramic components, including 5 involving Biolox Delta. Manufacturer's data and ANSM (Agence nationale de sécurité du médicament et des produits de santé) (National Agency for Safety of Drugs and Medical Products) reports were compared with the few clinical cases published in the literature. Results. According to the manufacturer (CeramTec GmbH, Plochingen, Germany), the use of Biolox Delta ceramic has reduced the rate of femoral head fractures to 0.003% compared to 0.021% with alumina ceramic. The fracture rate of liners has remained stable, at approximately 0.03%. The number of ANSM reports confirmed these tendencies. The rate of head component fractures decreases as the head diameter increases. The quality of impaction on the morse taper (cleanliness of the taper, insertion along the axis) plays an important role. Although it is generally only available for cup sizes above 50mm, a 36-mm head diameter seems to be optimal because it prevents impingement between the cup rim and the neck of the stem, without increasing micro-separation with larger diameters. Conclusion. Although Biolox Delta ceramic is more resistant to fractures than alumina ceramic, it can be fractured under suboptimal implantation

  20. Visibility graph analysis of heart rate time series and bio-marker of congestive heart failure

    NASA Astrophysics Data System (ADS)

    Bhaduri, Anirban; Bhaduri, Susmita; Ghosh, Dipak

    2017-09-01

    Study of RR interval time series for Congestive Heart Failure had been an area of study with different methods including non-linear methods. In this article the cardiac dynamics of heart beat are explored in the light of complex network analysis, viz. visibility graph method. Heart beat (RR Interval) time series data taken from Physionet database [46, 47] belonging to two groups of subjects, diseased (congestive heart failure) (29 in number) and normal (54 in number) are analyzed with the technique. The overall results show that a quantitative parameter can significantly differentiate between the diseased subjects and the normal subjects as well as different stages of the disease. Further, the data when split into periods of around 1 hour each and analyzed separately, also shows the same consistent differences. This quantitative parameter obtained using the visibility graph analysis thereby can be used as a potential bio-marker as well as a subsequent alarm generation mechanism for predicting the onset of Congestive Heart Failure.

  1. Suppression of large earthquakes by stress shadows: A comparison of Coulomb and rate-and-state failure

    NASA Astrophysics Data System (ADS)

    Harris, Ruth A.; Simpson, Robert W.

    1998-10-01

    Stress shadows generated by California's two most recent great earthquakes (1857 Fort Tejon and 1906 San Francisco) substantially modified 19th and 20th century earthquake history in the Los Angeles basin and in the San Francisco Bay area. Simple Coulomb failure calculations, which assume that earthquakes can be modeled as static dislocations in an elastic half-space, have done quite well at approximating how long the stress shadows, or relaxing effects, should last and at predicting where subsequent large earthquakes will not occur. There has, however, been at least one apparent exception to the predictions of such simple models. The 1911 M>6.0 earthquake near Morgan Hill, California, occurred at a relaxed site on the Calaveras fault. We examine how the more complex rate-and-state friction formalism based on laboratory experiments might have allowed the 1911 earthquake. Rate-and-state time-to-failure calculations are consistent with the occurrence of the 1911 event just 5 years after 1906 if the Calaveras fault was already close to failure before the effects of 1906. We also examine the likelihood that the entire 78 years of relative quiet (only four M≥6 earthquakes) in the bay area after 1906 is consistent with rate-and-state assumptions, given that the previous 7 decades produced 18 M≥6 earthquakes. Combinations of rate-and-state variables can be found that are consistent with this pattern of large bay area earthquakes, assuming that the rate of earthquakes in the 7 decades before 1906 would have continued had 1906 not occurred. These results demonstrate that rate-and-state offers a consistent explanation for the 78-year quiescence and the 1911 anomaly, although they do not rule out several alternate explanations.

  2. Structures for attaching or sealing a space between components having different coefficients or rates of thermal expansion

    DOEpatents

    Corman, Gregory Scot; Dean, Anthony John; Tognarelli, Leonardo; Pecchioli, Mario

    2005-06-28

    A structure for attaching together or sealing a space between a first component and a second component that have different rates or amounts of dimensional change upon being exposed to temperatures other than ambient temperature. The structure comprises a first attachment structure associated with the first component that slidably engages a second attachment structure associated with the second component, thereby allowing for an independent floating movement of the second component relative to the first component. The structure can comprise split rings, laminar rings, or multiple split rings.

  3. Multidimensional Life Table Estimation of the Total Fertility Rate and Its Components

    PubMed Central

    Retherford, Robert D.; Eini-Zinab, Hassan; Choe, Minja Kim; Ogawa, Naohiro; Matsukura, Rikiya

    2013-01-01

    Using discrete-time survival models of parity progression and illustrative data from the Philippines, this article develops a multivariate multidimensional life table of nuptiality and fertility, the dimensions of which are age, parity, and duration in parity. The measures calculated from this life table include total fertility rate (TRF), total marital fertility rate (TMFR), parity progression ratios (PPR), age-specific fertility rates, mean and median ages at first marriage, mean and median closed birth intervals, and mean and median ages at childbearing by child’s birth order and for all birth orders combined. These measures are referred to collectively as “TFR and its components.” Because the multidimensional life table is multivariate, all measures derived from it are also multivariate in the sense that they can be tabulated by categories or selected values of one socioeconomic variable while controlling for other socioeconomic variables. The methodology is applied to birth history data, in the form of actual birth histories from a fertility survey or reconstructed birth histories derived from a census or household survey. The methodology yields period estimates as well as cohort estimates of the aforementioned measures. PMID:23264037

  4. Low Rates of Treatment Failure in Children Aged 2–59 Months Treated for Severe Pneumonia: A Multisite Pooled Analysis

    PubMed Central

    Fox, Matthew P.; Thea, Donald M.; Sadruddin, Salim; Bari, Abdul; Bonawitz, Rachael; Hazir, Tabish; Bin Nisar, Yasir; Qazi, Shamim A.

    2013-01-01

    Background. Despite advances in childhood pneumonia management, it remains a major killer of children worldwide. We sought to estimate global treatment failure rates in children aged 2–59 months with World Health Organization–defined severe pneumonia. Methods. We pooled data from 4 severe pneumonia studies conducted during 1999–2009 using similar methodologies. We defined treatment failure by day 6 as death, danger signs (inability to drink, convulsions, abnormally sleepy), fever (≥38°C) and lower chest indrawing (LCI; days 2–3), LCI (day 6), or antibiotic change. Results. Among 6398 cases of severe pneumonia from 10 countries, 564 (cluster adjusted: 8.5%; 95% confidence interval [CI], 5.9%–11.5%) failed treatment by day 6. The most common reasons for clinical failure were persistence of fever and LCI or LCI or fever alone (75% of failures). Seventeen (0.3%) children died. Danger signs were uncommon (<1%). Infants 6–11 months and 2–5 months were 2- and 3.5-fold more likely, respectively, to fail treatment (adjusted OR [AOR], 1.8 [95% CI, 1.4–2.3] and AOR, 3.5 [95% CI, 2.8–4.3]) as children aged 12–59 months. Failure was increased 7-fold (AOR, 7.2 [95% CI, 5.0–10.5]) when comparing infants 2–5 months with very fast breathing to children 12–59 months with normal breathing. Conclusions. Our findings demonstrate that severe pneumonia case management with antibiotics at health facilities or in the community is associated with few serious morbidities or deaths across diverse geographic settings and support moves to shift management of severe pneumonia with oral antibiotics to outpatients in the community. PMID:23264361

  5. Pulse Generator Exchange Does Not Accelerate the Rate of Electrical Failure in a Recalled Small Caliber ICD Lead.

    PubMed

    Lovelock, Joshua D; Premkumar, Ajay; Levy, Mathew R; Mengistu, Andenet; Hoskins, Michael H; El-Chami, Mikhael F; Lloyd, Michael S; Leon, Angel R; Langberg, Jonathan J; Delurgio, David B

    2015-12-01

    St. Jude Riata/Riata ST defibrillator leads (St. Jude Medical, Sylmar, CA, USA) were recalled by the Food and Drug Administration in 2011 for an increased rate of failure. More than 227,000 leads were implanted and at least 79,000 patients still have active Riata leads. Studies have examined clinical predictors of lead failure in Riata leads, but none have addressed the effect of implantable cardioverter defibrillator (ICD) generator exchange on lead failure. The purpose of this study is to assess the effect of ICD generator exchange on the rate of electrical failure in the Riata lead at 1 year. A retrospective chart review was conducted in patients who underwent implantation of a Riata/Riata ST lead at one center. Patients with a functioning Riata lead (with/without externalized conductor) at the time of ICD exchange were compared to controls with Riata leads implanted for a comparable amount of time who did not undergo generator replacement. Riata leads were implanted in 1,042 patients prior to the recall and 153 of these patients underwent generator exchange without lead replacement. Conductor externalization was noted in 21.5% of Riata leads in the ICD exchange cohort, which was not different from the control group (19.2%; P = 0.32). Two leads failed in the first year after generator replacement (1.5%) which did not significantly differ from the control group (2.0%; P = 0.57). At change-out, 54% received a commanded shock (18.6 ± 0.9 J) that did not result in any change in the high-voltage lead impedance (46.1 ± 1.1 ohms). Conductor externalization was seen frequently in our cohort of patients. ICD generator exchange did not accelerate the rate of Riata lead failure at 1 year. Although both the control and the change-out cohorts failed at a rate much greater than nonrecalled leads, generator exchange did not appear to add to the problem. ©2015 Wiley Periodicals, Inc.

  6. Success rate and risk factors of failure of the induced membrane technique in children: a systematic review.

    PubMed

    Aurégan, Jean-Charles; Bégué, Thierry; Rigoulot, Guillaume; Glorion, Christophe; Pannier, Stéphanie

    2016-12-01

    The induced membrane technique was designed by Masquelet et al. to address segmental bone defects of critical size in adults. It has been used after bone defects of traumatic, infectious and tumoral origin with satisfactory results. Recently, it has been used in children but, after an initial enthusiasm, several cases of failure have been reported. The purpose of this study was to assess the success rate and the risk factors of failure of the induced membrane for children. We conducted a systematic review of all the studies reporting the results of the induced membrane technique to address bone defects of critical size in children. Our primary outcome was the success rate of the technique defined as a bone union before any iterative surgery. Our secondary outcomes were the complications and the risk factors of failure. We searched Medline via Pubmed, EMBASE and the Cochrane Library. Twelve studies, including 69 patients, met the inclusion criteria. There were 41 boys and 28 girls. Mean age at surgery was 10 years. Mean size of resection was 12.38 cm and the mean time between the two stages was 5.86 months. Mean rate of bone union after the two stages of the induced membrane technique was 58% (40/69) but this rate increased to 87% after revision surgeries (60/69). Main complications were non-unions (19/69), lysis of the graft (6/69) and fractures of the bone graft (6/69). Only 1/69 deep infection was reported. Other non specific complications were regularly reported such limb length discrepancies, joint stiffness and protruding wires. Risk factor of failure that could be suspected comprised the resection of a malignant tumour, a bone defect located at the femur, a wide resection, a long time between the two stages, an unstable osteosynthesis and a bone graft associating autograft to other graft materials. The induced membrane technique is suitable for bone defects of critical size in children. It is a reliable technique with no need of micro vascular surgery

  7. Higher Rate of Revision in PFC Sigma Primary Total Knee Arthroplasty With Mismatch of Femoro-Tibial Component Sizes.

    PubMed

    Young, Simon W; Clarke, Henry D; Graves, Stephen E; Liu, Yen-Liang; de Steiger, Richard N

    2015-05-01

    Total knee arthroplasty (TKA) systems permit a degree of femoro-tibial component size mismatch. The effect of mismatched components on revision rates has not been evaluated in a large study. We reviewed 21,906 fixed-bearing PFC Sigma primary TKAs using the Australian Orthopaedic Association National Joint Replacement Registry, dividing patients into three groups: no femoro-tibial size mismatch, tibial component size > femoral component size, and femoral component > tibial component. Revision rates were higher when the femoral size was greater than the tibia, compared to both equal size (HR = 1.20 (1.00, 1.45), P = 0.047) and to tibial size greater than femoral (HR = 1.60 (1.08, 2.37), P = 0.019). Potential mechanisms to explain these findings include edge loading of polyethylene and increased tibial component stresses.

  8. Two-component mixture model: Application to palm oil and exchange rate

    NASA Astrophysics Data System (ADS)

    Phoong, Seuk-Yen; Ismail, Mohd Tahir; Hamzah, Firdaus Mohamad

    2014-12-01

    Palm oil is a seed crop which is widely adopt for food and non-food products such as cookie, vegetable oil, cosmetics, household products and others. Palm oil is majority growth in Malaysia and Indonesia. However, the demand for palm oil is getting growth and rapidly running out over the years. This phenomenal cause illegal logging of trees and destroy the natural habitat. Hence, the present paper investigates the relationship between exchange rate and palm oil price in Malaysia by using Maximum Likelihood Estimation via Newton-Raphson algorithm to fit a two components mixture model. Besides, this paper proposes a mixture of normal distribution to accommodate with asymmetry characteristics and platykurtic time series data.

  9. Analysis of Photosynthetic Rate and Bio-Optical Components from Ocean Color Imagery

    NASA Technical Reports Server (NTRS)

    Kiefer, Dale A.; Stramski, Dariusz

    1997-01-01

    Our research over the last 5 years indicates that the successful transformation of ocean color imagery into maps of bio-optical properties will require continued development and testing of algorithms. In particular improvements in the accuracy of predicting from ocean color imagery the concentration of the bio-optical components of sea as well as the rate of photosynthesis will require progress in at least three areas: (1) we must improve mathematical models of the growth and physiological acclimation of phytoplankton; (2) we must better understand the sources of variability in the absorption and backscattering properties of phytoplankton and associated microparticles; and (3) we must better understand how the radiance distribution just below the sea surface varies as a function sun and sky conditions and inherent optical properties.

  10. Research on Fault Rate Prediction Method of T/R Component

    NASA Astrophysics Data System (ADS)

    Hou, Xiaodong; Yang, Jiangping; Bi, Zengjun; Zhang, Yu

    2017-07-01

    T/R component is an important part of the large phased array radar antenna array, because of its large numbers, high fault rate, it has important significance for fault prediction. Aiming at the problems of traditional grey model GM(1,1) in practical operation, the discrete grey model is established based on the original model in this paper, and the optimization factor is introduced to optimize the background value, and the linear form of the prediction model is added, the improved discrete grey model of linear regression is proposed, finally, an example is simulated and compared with other models. The results show that the method proposed in this paper has higher accuracy and the solution is simple and the application scope is more extensive.

  11. Evaluation of components, subsystems, and networks for high rate, high frequency space communications

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Ivancic, William D.; Zuzek, John E.

    1991-01-01

    The development of new space communications technologies by NASA has included both commercial applications and space science requirements. NASA's Systems Integration, Test and Evaluation (SITE) Space Communication System Simulator is a hardware based laboratory simulator for evaluating space communications technologies at the component, subsystem, system, and network level, geared toward high frequency, high data rate systems. The SITE facility is well-suited for evaluation of the new technologies required for the Space Exploration Initiative (SEI) and advanced commercial systems. Described here are the technology developments and evaluation requirements for current and planned commercial and space science programs. Also examined are the capabilities of SITE, the past, present and planned future configurations of the SITE facility, and applications of SITE to evaluation of SEI technology.

  12. Ductile failure of steel HY80 under high strain rates and triaxial stress states, experimental results and damage description

    NASA Astrophysics Data System (ADS)

    Abdel-Malek, S.; Halle, Th.; Meyer, L. W.

    2003-09-01

    Ductile fracture investigations are an important part in current research. The simulation of fracture by means of numerical codes needs precise material data that may be reached from accurate mechanical testing. In order to predict failure processes, the stress state history as a function of strain development has to be known. In this work tensile tests on HY80 steel were performed under quasistatic and high strain rate loading conditions at room temperature using smooth and notched specimens. The force-time and displacement-time behaviour was measured during testing. Additionally, scanning electron microscopy was used to investigate the fractured surfaces. Furthermore, different models were applied to describe the failure process. FE-calculations were used to receive the stress state in the material in the region of the notch as a function of strain development.

  13. A Krebs Cycle Component Limits Caspase Activation Rate through Mitochondrial Surface Restriction of CRL Activation.

    PubMed

    Aram, Lior; Braun, Tslil; Braverman, Carmel; Kaplan, Yosef; Ravid, Liat; Levin-Zaidman, Smadar; Arama, Eli

    2016-04-04

    How cells avoid excessive caspase activity and unwanted cell death during apoptotic caspase-mediated removal of large cellular structures is poorly understood. We investigate caspase-mediated extrusion of spermatid cytoplasmic contents in Drosophila during spermatid individualization. We show that a Krebs cycle component, the ATP-specific form of the succinyl-CoA synthetase β subunit (A-Sβ), binds to and activates the Cullin-3-based ubiquitin ligase (CRL3) complex required for caspase activation in spermatids. In vitro and in vivo evidence suggests that this interaction occurs on the mitochondrial surface, thereby limiting the source of CRL3 complex activation to the vicinity of this organelle and reducing the potential rate of caspase activation by at least 60%. Domain swapping between A-Sβ and the GTP-specific SCSβ (G-Sβ), which functions redundantly in the Krebs cycle, show that the metabolic and structural roles of A-Sβ in spermatids can be uncoupled, highlighting a moonlighting function of this Krebs cycle component in CRL activation. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Guidelines to achieve seals with minimal leak rates for HWR-NPR coolant system components

    SciTech Connect

    Finn, P.A.

    1991-03-01

    Seal design practices that are acceptable in pressurized-water and boiling-water reactors in the United States are not usable for the Heavy Water Reactor-New Production Reactor (HWR-NPR) because of the stringent requirement on tritium control for the atmosphere within its containment building. To maintain an atmosphere in which workers do not need protective equipment, the components of the coolant system must have a cumulative leak rate less than 0.00026 L/s. Existing technology for seal systems was reviewed with regard to flange, elastomer, valve, and pump design. A technology data base for the designers of the HWR-NPR coolant system was derived from operating experience and seal development work on reactors in the United States, Canada, and Europe. This data base was then used to generate guidelines for the design of seals and/or joints for the HWR-NPR coolant system. Also discussed are needed additional research and development, as well as the necessary component qualification tests for an effective quality control program. 141 refs., 21 figs., 14 tabs.

  15. Measurement for the dose-rates of the cosmic-ray components on the ground.

    PubMed

    Rasolonjatovo, Danielle A H; Suzuki, Hiroyuki; Hirabayashi, Naoya; Nunomiya, Tomoya; Nakamura, Takashi; Nakao, Noriaki

    2002-12-01

    In this study, we aimed to measure the directly ionizing component (muons and photons) and the indirectly ionizing component (neutrons) of the cosmic-ray spectra and evaluate their dose rate contribution to the total dose rate on a ground level in Japan. Measurements were carried out in Tohoku University, Japan, from October 2000. The pulse-height spectra of the cosmic-ray photons and muons were measured with a 12.7 cm diameter and 12.7 cm long NaI(Tl) scintillation detector. In order to measure energy spectra of cosmic-ray photons and muons, response functions of the detector to photons and muons were determined by the Monte Carlo simulation codes. The cosmic-ray photon dose was evaluated directly from the measured pulse-height spectrum by using the spectrum weight function, and the cosmic-ray muon dose was evaluated by converting the measured pulse height spectrum into deposited energy within the detector. The quantity of the cosmic-ray electrons is estimated to be very small and is not taken into account in this study. The cosmic-ray neutron spectrum and the neutron dose were measured by using a multi-moderator spectrometer (Bonner ball) and a rem counter. The measurements could finally give the annual absorbed dose in tissue of the cosmic-ray muons of 315 microSv/y and annual ambient doses of the cosmic-ray photons and neutrons on the ground in Japan of 55 microSv/y and 31 microSv/y, respectively.

  16. A comparison of volume-equated knee extensions to failure, or not to failure, upon rating of perceived exertion and strength adaptations.

    PubMed

    Fisher, James Peter; Blossom, Dominic; Steele, James

    2016-02-01

    The present study aimed to compare the effects of repetition duration-, volume-, and load-matched resistance training to muscular failure (MMF) or not to muscular failure (NMF) on maximal voluntary isometric knee extensor strength. This design also allowed testing of the efficacy of "5×5" training. Nine recreationally active males (age, 21.4 ± 1.2 years; height, 1.79 ± 0.07 m; weight, 78.4 ± 7.1 kg) performed unilateral resistance training at 80% of maximal torque at 2×/week for 6 weeks. Using their nondominant leg, participants performed 5 sets of 5 repetitions (NMF). Using their dominant leg, participants performed 25 repetitions in as few sets as possible (MMF). All repetitions were performed at a pace of 2 s concentric, 1 s isometric pause, and 2 s eccentric with a 2-min rest interval between sets. Analyses identified significant pre- to post-intervention strength increases for both MMF and NMF, with effect sizes (ESs) of 2.01 and 1.65, respectively, with no significant differences between conditions (p > 0.05). Peak and mean ratings of perceived exertion (RPEs) were significantly higher for MMF compared with NMF conditions (p < 0.0001), and a tendency for significantly higher RPE values reported for later sets for the NMF condition. Total training time per session was significantly longer for NMF compared with MMF (p < 0.001). The present study suggests that in untrained participants, resistance training NMF produces equivocally the same strength increases as training to MMF when volume-matched. However, resistance training to MMF appears to be a more time-efficient protocol and may produce greater strength gains as indicated by a larger ES.

  17. A failure modes and effects analysis study for gynecologic high-dose-rate brachytherapy.

    PubMed

    Mayadev, Jyoti; Dieterich, Sonja; Harse, Rick; Lentz, Susan; Mathai, Mathew; Boddu, Sunita; Kern, Marianne; Courquin, Jean; Stern, Robin L

    2015-01-01

    To improve the quality of our gynecologic brachytherapy practice and reduce reportable events, we performed a process analysis after the failure modes and effects analysis (FMEA). The FMEA included a multidisciplinary team specifically targeting the tandem and ring brachytherapy procedure. The treatment process was divided into six subprocesses and failure modes (FMs). A scoring guideline was developed based on published FMEA studies and assigned through team consensus. FMs were ranked according to overall and severity scores. FM ranking >5% of the highest risk priority number (RPN) score was selected for in-depth analysis. The efficiency of each existing quality assurance to detect each FM was analyzed. We identified 170 FMs, and 99 were scored. RPN scores ranged from 1 to 192. Of the 13 highest-ranking FMs with RPN scores >80, half had severity scores of 8 or 9, with no mode having severity of 10. Of these FM, the originating process steps were simulation (5), treatment planning (5), treatment delivery (2), and insertion (1). Our high-ranking FM focused on communication and the potential for applicator movement. Evaluation of the efficiency and the comprehensiveness of our quality assurance program showed coverage of all but three of the top 49 FMs ranked by RPN. This is the first reported FMEA process for a comprehensive gynecologic brachytherapy procedure overview. We were able to identify FMs that could potentially and severely impact the patient's treatment. We continue to adjust our quality assurance program based on the results of our FMEA analysis. Published by Elsevier Inc.

  18. Analyzing 30-Day Readmission Rate for Heart Failure Using Different Predictive Models.

    PubMed

    Mahajan, Satish; Burman, Prabir; Hogarth, Michael

    2016-01-01

    The Center for Medicare and Medical Services in the United States compares hospital's readmission performance to the facilities across the nation using a 30-day window from the hospital discharge. Heart Failure (HF) is one of the conditions included in the comparison, as it is the most frequent and the most expensive diagnosis for hospitalization. If risk stratification for readmission of HF patients could be carried out at the time of discharge from the index hospitalization, corresponding appropriate post-discharge interventions could be arranged. We, therefore, sought to compare two different risk prediction models using 48 clinical predictors from electronic health records data of 1037 HF patients from one hospital. We used logistic regression and random forest as methods of analyses and found that logistic regression with bagging approach produced better predictive results (C-Statistics: 0.65) when compared to random forest (C-Statistics: 0.61).

  19. Development of KSC program for investigating and generating field failure rates. Volume 1: Summary and overview

    NASA Technical Reports Server (NTRS)

    Bean, E. E.; Bloomquist, C. E.

    1972-01-01

    A summary of the KSC program for investigating the reliability aspects of the ground support activities is presented. An analysis of unsatisfactory condition reports (RC), and the generation of reliability assessment of components based on the URC are discussed along with the design considerations for attaining reliable real time hardware/software configurations.

  20. "Rate and mechanics of progressive hillslope failure in the Redwood Creek basin, northwestern California"

    Treesearch

    D. N. Swanston; R. R. Ziemer; R. J. Janda

    1995-01-01

    Abstract - Both creep and earthflow processes dominate hillslope erosion over large parts of the Redwood Creek basin. The type of process and the displacement rates are largely dependent on underlying bedrock type and precipitation. Progressive creep having rates ranging from 1.0 to 2.5 mm/a dominates on slopes west of the Grogan fault underlain by sheared and...

  1. Rate and mechanics of progressive hillslope failure in the Redwood Creek basin, northwestern California

    Treesearch

    D. N. Swanston; R.R. Ziemerm; R.J. Janda

    1995-01-01

    Both creep and earthflow processes dominate hillslope erosion over large parts of the Redwood Creek basin. The type of process and the displacement rates are largely dependent on underlying bedrock type and precipitation. Progressive creep having rates ranging from 1.0 to 2.5 mm/a dominates on slopes west of the Grogan fault underlain by sheared and foliated schists....

  2. MTBF evaluation for 2-out-of-3 redundant repairable systems with common cause and cascade failures considering fuzzy rates for failures and repair: a case study of a centrifugal water pumping system

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyed Mohammad; Mohamadi, Maryam; Jouzdani, Javid

    2017-08-01

    In many cases, redundant systems are beset by both independent and dependent failures. Ignoring dependent variables in MTBF evaluation of redundant systems hastens the occurrence of failure, causing it to take place before the expected time, hence decreasing safety and creating irreversible damages. Common cause failure (CCF) and cascading failure are two varieties of dependent failures, both leading to a considerable decrease in the MTBF of redundant systems. In this paper, the alpha-factor model and the capacity flow model are combined so as to incorporate CCF and cascading failure in the evaluation of MTBF of a 2-out-of-3 repairable redundant system. Then, using a transposed matrix, the MTBF function of the system is determined. Due to the fact that it is difficult to estimate the independent and dependent failure rates, industries are interested in considering uncertain failure rates. Therefore, fuzzy theory is used to incorporate uncertainty into the model presented in this study, and a nonlinear programming model is used to determine system's MTBF. Finally, in order to validate the proposed model, evaluation of MTBF of the redundant system of a centrifugal water pumping system is presented as a practical example.

  3. Long-duration correlation and attractor topology of the heartbeat rate differ for healthy patients and those with heart failure

    NASA Astrophysics Data System (ADS)

    Turcott, Robert G.; Teich, Malvin C.

    1993-11-01

    The point process formed by the sequence of human heartbeats exhibits long-duration power- law correlation. We obtain the normalized coincidence rate g(2)((tau) ) of the underlying point process and demonstrate that the correlation is stronger for patients with normal hearts than those with heart failure. This is consistent with the greater rate fluctuations observed in the normal heart. A number of statistical measures are used to establish the existence and reveal the form of the correlation, including rescaled range analysis, pulse- number distribution, Fano-factor time curve (FFC), and power spectral density. The normalized coincidence rate is obtained from the FFC. The long-duration, power-law correlation observed in the sequence of heartbeats is similar to that observed at a number of neurophysiological loci in a variety of species. We also obtain the box-counting estimate of the attractor's fractal dimension from a phase-space reconstruction and analysis of the trajectory of the number of heartbeat events. This approach reveals that the heartbeats of normal patients exhibit an attractor of higher dimension than those of heart-failure patients.

  4. Evaluation of errors in prior mean and variance in the estimation of integrated circuit failure rates using Bayesian methods

    NASA Technical Reports Server (NTRS)

    Fletcher, B. C.

    1972-01-01

    The critical point of any Bayesian analysis concerns the choice and quantification of the prior information. The effects of prior data on a Bayesian analysis are studied. Comparisons of the maximum likelihood estimator, the Bayesian estimator, and the known failure rate are presented. The results of the many simulated trails are then analyzed to show the region of criticality for prior information being supplied to the Bayesian estimator. In particular, effects of prior mean and variance are determined as a function of the amount of test data available.

  5. Improving the Estimates of International Space Station (ISS) Induced K-Factor Failure Rates for On-Orbit Replacement Unit (ORU) Supportability Analyses

    NASA Technical Reports Server (NTRS)

    Anderson, Leif F.; Harrington, Sean P.; Omeke, Ojei, II; Schwaab, Douglas G.

    2009-01-01

    This is a case study on revised estimates of induced failure for International Space Station (ISS) on-orbit replacement units (ORUs). We devise a heuristic to leverage operational experience data by aggregating ORU, associated function (vehicle sub -system), and vehicle effective' k-factors using actual failure experience. With this input, we determine a significant failure threshold and minimize the difference between the actual and predicted failure rates. We conclude with a discussion on both qualitative and quantitative improvements the heuristic methods and potential benefits to ISS supportability engineering analysis.

  6. Association of Holter-Derived Heart Rate Variability Parameters With the Development of Congestive Heart Failure in the Cardiovascular Health Study.

    PubMed

    Patel, Vaiibhav N; Pierce, Brian R; Bodapati, Rohan K; Brown, David L; Ives, Diane G; Stein, Phyllis K

    2017-06-01

    This study sought to determine whether Holter-based parameters of heart rate variability (HRV) are independently associated with incident heart failure among older adults in the CHS (Cardiovascular Health Study) as evidenced by an improvement in the predictive power of the Health Aging and Body Composition Heart Failure (Health ABC) score. Abnormal HRV, a marker of autonomic dysfunction, has been associated with multiple adverse cardiovascular outcomes but not the development of congestive heart failure (CHF). Asymptomatic CHS participants with interpretable 24-h baseline Holter recordings were included (n = 1,401). HRV measures and premature ventricular contraction (PVC) counts were compared between participants with (n = 260) and without (n = 1,141) incident CHF on follow-up. Significantly different parameters between groups were added to the components of the Health ABC score, a validated CHF prediction tool, using stepwise Cox regression. The final model included components of the Health ABC score, In PVC counts (adjusted hazard ratio [aHR]: 1.12; 95% confidence interval [CI]: 1.07 to 1.19; p < 0.001) and the following HRV measures: abnormal heart rate turbulence onset (aHR: 1.52; 95% CI: 1.11 to 2.08; p = 0.009), short-term fractal scaling exponent (aHR: 0.27; 95% CI: 0.14 to 0.53; p < 0.001), in very low frequency power (aHR: 1.28; 95% CI: 1.02 to 1.60; p = 0.037), and coefficient of variance of N-N intervals (aHR: 0.94; 95% CI: 0.90 to 0.99; p = 0.009). The C-statistic for the final model was significantly improved over the Health ABC model alone (0.77 vs. 0.73; p = 0.0002). Abnormal HRV parameters were significantly and independently associated with incident CHF in asymptomatic, older adults. When combined with increased PVCs, HRV improved the predictive power of the Health ABC score. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  7. Genetic component of sensitivity to heat stress for nonreturn rate of Brazilian Holstein cattle.

    PubMed

    Santana, M L; Bignardi, A B; Stefani, G; El Faro, L

    2017-08-01

    The objectives of the present study were: 1) to investigate variation in the genetic component of heat stress for nonreturn rate at 56 days after first artificial insemination (NR56); 2) to identify and characterize the genotype by environment interaction (G × E) due to heat stress for NR56 of Brazilian Holstein cattle. A linear random regression model (reaction norm model) was applied to 51,748 NR56 records of 28,595 heifers and multiparous cows. The decline in NR56 due to heat stress was more pronounced in milking cows compared to heifers. The age of females at first artificial insemination and temperature-humidity index (THI) exerted an important influence on the genetic parameters of NR56. Several evidence of G × E on NR56 were found as the high slope/intercept ratio and frequent intersection of reaction norms. Additionally, the genetic correlation between NR56 at opposite extremes of the THI scale reached estimates below zero, indicating that few of the same genes are responsible for NR56 under conditions of thermoneutrality and heat stress. The genetic evaluation and selection for NR56 in Holstein cattle reared under (sub)tropical conditions should therefore take into consideration the genetic variation on age at insemination and G × E due to heat stress. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

    NASA Astrophysics Data System (ADS)

    Saleh, Joseph Homer; Geng, Fan; Ku, Michelle; Walker, Mitchell L. R.

    2017-10-01

    With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates. The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both

  9. Failure analysis of sandwich-type ceramic-on-ceramic hip joints: A spectroscopic investigation into the role of the polyethylene shell component.

    PubMed

    Okita, Shinya; Hasegawa, Masahiro; Takahashi, Yasuhito; Puppulin, Leonardo; Sudo, Akihiro; Pezzotti, Giuseppe

    2014-03-01

    The mechanisms leading to systematic failure in modular acetabular components with a sandwich insertion (alumina/polyethylene/titanium) have been reconsidered in light of the newly collected Raman spectroscopic results. Raman assessments were conducted on the polyethylene shells, which belonged to a series of six failed sandwich implants with in vivo lifetimes ranging between 2 and 9yr. With only one exception, all implants commonly showed dislodgment of the polyethylene shell during radiographic analyses prior to revision surgery. The polyethylene shell slipped out of the backing titanium shell, while always remaining integer to the ceramic liner. Four implants fractured at the ceramic liners, but their fractures occurred according to distinctly different patterns, which could be rationalized and classified. The insertion of the polyethylene layer, originally conceived to reduce the rigidity of the ceramic-on-ceramic bearing and to prevent impingement between the ceramic liner rim and the femoral neck, played a role in implant failure with its initial (asymmetric) thickness reduction due to creep deformation (eventually followed by cup rotation and backside wear). The results of the present spectroscopic investigation suggest that a simplistic failure classification of the sandwich-type implant as a "ceramic fracture failure" could be misleading and might represent a confounding factor in judging about the reliability of modern ceramic implants. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Benefits of Heart Rate Slowing With Ivabradine in Patients With Systolic Heart Failure and Coronary Artery Disease.

    PubMed

    Borer, Jeffrey S; Deedwania, Prakash C; Kim, Jae B; Böhm, Michael

    2016-12-15

    Heart rate (HR) is a risk factor in patients with chronic systolic heart failure (HF) that, when reduced, provides outcome benefits. It is also a target for angina pectoris prevention and a risk marker in chronic coronary artery disease without HF. HR can be reduced by drugs; however, among those used clinically, only ivabradine reduces HR directly in the sinoatrial nodal cells without other known effects on the cardiovascular system. This review provides current information regarding the safety and efficacy of HR reduction with ivabradine in clinical studies involving >36,000 patients with chronic stable coronary artery disease and >6,500 patients with systolic HF. The largest trials, Morbidity-Mortality Evaluation of the If Inhibitor Ivabradine in Patients With Coronary Disease and Left Ventricular Dysfunction and Study Assessing the Morbidity-Mortality Benefits of the If Inhibitor Ivabradine in Patients With Coronary Artery Disease, showed no effect on outcomes. The Systolic Heart Failure Treatment With the If Inhibitor Ivabradine Trial, a randomized controlled trial in >6,500 patients with HF, revealed marked and significant HR-mediated reduction in cardiovascular mortality or HF hospitalizations while improving quality of life and left ventricular mechanical function after treatment with ivabradine. The adverse effects of ivabradine predominantly included bradycardia and atrial fibrillation (both uncommon) and ocular flashing scotomata (phosphenes) but otherwise were similar to placebo. In conclusion, ivabradine improves outcomes in patients with systolic HF; rates of overall adverse events are similar to placebo. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Particulate Air Pollution and the Rate of Hospitalization for Congestive Heart Failure among Medicare Beneficiaries in Pittsburgh, Pennsylvania.

    PubMed Central

    Wellenius, Gregory A.; Bateson, Thomas F.; Mittleman, Murray A.; Schwartz., Joel

    2006-01-01

    We used a case-crossover approach to evaluate the association between ambient air pollution and the rate of hospitalization for congestive heart failure (CHF) among Medicare recipients (age ≥ 65) residing in Allegheny County (Pittsburgh area), PA, during 1987–1999. We also explored effect modification by age, gender, and specific secondary diagnoses. During follow-up, there were 55,019 admissions with a primary diagnosis of CHF. We found that particulate matter with aerodynamic diameter ≤ 10 μm (PM10), carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide – but not ozone – were positively and significantly associated with the rate of admission on the same day in single-pollutant models. The strongest associations were observed with CO, NO2 and PM10. The associations with CO and NO2 were the most robust in two-pollutant models, remaining statistically significant even after adjusting for other pollutants. Patients with a recent myocardial infarction were at greater risk of particulate-related admission, but there was otherwise no significant effect modification by age, gender, or other secondary diagnoses. These results suggest that short-term elevations in air pollution from traffic-related sources may trigger acute cardiac decompensation of heart failure patients and that those with certain comorbid conditions may be more susceptible to these effects. PMID:15901623

  12. Multi-rate soliton pulse train generator based on novel fiber optic components

    NASA Astrophysics Data System (ADS)

    Sova, Raymond Michael

    As data rates for communication, signal processing, and optical sensing systems increase beyond 50 Gb/sec, ultra-fast optical pulse train generators will play a key role in their development. In this research, an all-fiber optical soliton pulse train generator is developed that operates at discrete rates from 50 to 400 Gb/sec with stable subpicosecond pulses. It is based on the following three novel fiber optic components: (1) all-fiber birefringence filter, (2) dual-wavelength fiber ring laser and (3) fiber-based soliton pulse train generation and compression stage. A multi-segment birefringence comb filter is developed to provide discrete tuning of the free spectral range from 0.8 to 3.2 nm and continuous tuning of the absolute position of the transmission peaks over the entire free spectral range. Two, three and four segment filters are constructed and implemented in Lyot and Lyot-Sagnac filter configurations to demonstrate the tuning properties and provide compound filters for use in the dual-wavelength fiber ring laser. Theoretical transmission functions are derived for two-segment filters. The experimental results are in excellent agreement with theoretical models based on the Jones matrix technique. The dual-wavelength laser consists of a PM amplifier, the tunable birefringence filter and a high-Q filter based on saturable absorber properties of un-pumped Erbium-doped fiber. Tunable compound birefringence filters are designed to operate the dual-wavelength laser over the entire erbium amplifier gain region (1530 to 1565 nm) with discrete tuning of the channel separation from 0.8 to 3.2 nm. Stable tunable dual-wavelength single-longitudinal mode operation is demonstrated and initial laser properties such as dual-relaxation oscillations, laser linewidth, polarization, and multi-wavelength stability are characterized. Induced modulation instability in optical fiber is used to generate pulse trains from the fiber ring laser output signal. Through modeling, the

  13. Multicenter Osteopathic Pneumonia Study in the Elderly: Subgroup Analysis on Hospital Length of Stay, Ventilator-Dependent Respiratory Failure Rate, and In-hospital Mortality Rate.

    PubMed

    Noll, Donald R; Degenhardt, Brian F; Johnson, Jane C

    2016-09-01

    Osteopathic manipulative treatment (OMT) is a promising adjunctive treatment for older adults hospitalized for pneumonia. To report subgroup analyses from the Multicenter Osteopathic Pneumonia Study in the Elderly (MOPSE) relating to hospital length of stay (LOS), ventilator-dependent respiratory failure rate, and in-hospital mortality rate. Multicenter randomized controlled trial. Seven community hospitals. Three hundred eighty-seven patients aged 50 years or older who met specific criteria for pneumonia on hospital admission. Participants were randomly assigned to 1 of 3 groups that received an adjunctive OMT protocol (n=130), a light touch (LT) protocol (n=124), or conventional care only (CCO) (n=133). Outcomes for subgroup analyses were LOS, ventilator-dependent respiratory failure rate, and in-hospital mortality rate. Subgroups were age (50-74 years or ≥75 years), Pneumonia Severity Index (PSI) class (I-II, III, IV, or V), and type of pneumonia (community-acquired or nursing-home acquired). Data were analyzed by intention-to-treat and per-protocol analyses using stratified Cox proportional hazards models and Cochran-Mantel-Haenszel tests for general association. By per-protocol analysis of the younger age subgroup, LOS was shorter for the OMT group (median, 2.9 days; n=43) than the LT (median, 3.7 days; n=45) and CCO (median, 4.0 days; n=65) groups (P=.006). By intention-to-treat analysis of the older age subgroup, in-hospital mortality rates were lower for the OMT (1 of 66 [2%]) and LT (2 of 68 [3%]) groups than the CCO group (9 of 67 [13%]) (P=.005). By per-protocol analysis of the PSI class IV subgroup, the OMT group had a shorter LOS than the CCO group (median, 3.8 days [n=40] vs 5.0 days [n=50]; P=.01) and a lower ventilator-dependent respiratory failure rate than the CCO group (0 of 40 [0%] vs 5 of 50 [10%]; P=.05). By intention-to-treat analysis, in-hospital mortality rates in the PSI class V subgroup were lower (P=.05) for the OMT group (1 of 22 [5

  14. Utility of overnight pulse oximetry and heart rate variability analysis to screen for sleep-disordered breathing in chronic heart failure.

    PubMed

    Ward, Neil R; Cowie, Martin R; Rosen, Stuart D; Roldao, Vitor; De Villa, Manuel; McDonagh, Theresa A; Simonds, Anita; Morrell, Mary J

    2012-11-01

    Sleep-disordered breathing (SDB) is under diagnosed in chronic heart failure (CHF). Screening with simple monitors may increase detection of SDB in a cardiology setting. This study aimed to evaluate the accuracy of heart rate variability analysis and overnight pulse oximetry for diagnosis of SDB in patients with CHF. 180 patients with CHF underwent simultaneous polysomnography, ambulatory electrocardiography and wrist-worn overnight pulse oximetry. SDB was defined as an apnoea-hypopnoea index ≥15/h. To identify SDB from the screening tests, the per cent very low frequency increment (%VLFI) component of heart rate variability was measured with a pre-specified cutoff ≥2.23%, and the 3% oxygen desaturation index was measured with a pre-specified cutoff >7.5 desaturations/h. 173 patients with CHF had adequate sleep study data; SDB occurred in 77 (45%) patients. Heart rate variability was measurable in 78 (45%) patients with area under the %VLFI receiver operating characteristic curve of 0.50. At the ≥2.23% cutoff, %VLFI sensitivity was 58% and specificity was 48%. The 3% oxygen desaturation index was measurable in 171 (99%) patients with area under the curve of 0.92. At the pre-specified cutoff of >7.5 desaturations/h, the 3% oxygen desaturation index had a sensitivity of 97%, specificity of 32%, negative likelihood ratio of 0.08 and positive likelihood ratio of 1.42. Diagnostic accuracy was increased using a cutoff of 12.5 desaturations/h, with sensitivity of 93% and specificity of 73%. The high sensitivity and low negative likelihood ratio of the 3% oxygen desaturation index indicates that pulse oximetry would be of use as a simple screening test to rule out SDB in patients with CHF in a cardiology setting. The %VLFI component of heart rate variability is not suitable for detection of SDB in CHF.

  15. Locoregional Failure Rate After Preoperative Chemoradiation of Esophageal Adenocarcinoma and the Outcomes of Salvage Strategies

    PubMed Central

    Sudo, Kazuki; Taketa, Takashi; Correa, Arlene M.; Campagna, Maria-Claudia; Wadhwa, Roopma; Blum, Mariela A.; Komaki, Ritsuko; Lee, Jeffrey H.; Bhutani, Manoop S.; Weston, Brian; Skinner, Heath D.; Maru, Dipen M.; Rice, David C.; Swisher, Stephen G.; Hofstetter, Wayne L.; Ajani, Jaffer A.

    2013-01-01

    Purpose The primary purpose of surveillance of patients with esophageal adenocarcinoma (EAC) and/or esophagogastric junction adenocarcinoma after local therapy (eg, chemoradiotherapy followed by surgery or trimodality therapy [TMT]) is to implement a potentially beneficial salvage therapy to overcome possible morbidity/mortality caused by locoregional failure (LRF). However, the benefits of surveillance are not well understood. We report on LRFs and salvage strategies in a large cohort. Patients and Methods Between 2000 and 2010, 518 patients with EAC who completed TMT were analyzed for the frequency of LRF over time and salvage therapy outcomes. Standard statistical techniques were used. Results For 518 patients, the median follow-up time was 29.3 months (range, 1 to 149 months). Distant metastases (with or without LRF) occurred in 188 patients (36%), and LRF only occurred in 27 patients (5%). Eleven of 27 patients had lumen-only LRF. Most LRFs (89%) occurred within 36 months of surgery. Twelve patients had salvage chemoradiotherapy, but only five survived more than 2 years. Four patients needed salvage surgery, and three who survived more than 2 years developed distant metastases. The median overall survival of 27 patients with LRF was 17 months, and 10 patients (37%) survived more than 2 years. Thus, only 2% of all 518 patients benefited from surveillance/salvage strategies. Conclusion Our surveillance strategy, which is representative of many others currently being used, raises doubts about its effectiveness and benefits (along with concerns regarding types and times of studies and costs implications) to patients with EAC who have LRF only after TMT. Fortunately, LRFs are rare after TMT, but the salvage strategies are not highly beneficial. Our data can help develop an evidence-based surveillance strategy. PMID:24145339

  16. The effect of different cooling rates and coping thicknesses on the failure load of zirconia-ceramic crowns after fatigue loading.

    PubMed

    Tang, Yu Lung; Kim, Jee-Hwan; Shim, June-Sung; Kim, Sunjai

    2017-06-01

    The purpose of this study was to evaluate the influence of different coping thicknesses and veneer ceramic cooling rates on the failure load of zirconia-ceramic crowns. Zirconia copings of two different thicknesses (0.5 mm or 1.5 mm; n=20 each) were fabricated from scanning 40 identical abutment models using a dental computer-aided design and computer-aided manufacturing system. Zirconia-ceramic crowns were completed by veneering feldspathic ceramics under different cooling rates (conventional or slow, n=20 each), resulting in 4 different groups (CONV05, SLOW05, CONV15, SLOW15; n=10 per group). Each crown was cemented on the abutment. 300,000 cycles of a 50-N load and thermocycling were applied on the crown, and then, a monotonic load was applied on each crown until failure. The mean failure loads were evaluated with two-way analysis of variance (P=.05). No cohesive or adhesive failure was observed after fatigue loading with thermocycling. Among the 4 groups, SLOW15 group (slow cooling and 1.5 mm chipping thickness) resulted in a significantly greater mean failure load than the other groups (P<.001). Coping fractures were only observed in SLOW15 group. The failure load of zirconia-ceramic crowns was significantly influenced by cooling rate as well as coping thickness. Under conventional cooling conditions, the mean failure load was not influenced by the coping thickness; however, under slow cooling conditions, the mean failure load was significantly influenced by the coping thickness.

  17. Effect of Noradrenergic Neurotoxin DSP-4 and Maprotiline on Heart Rate Spectral Components in Stressed and Resting Rats.

    PubMed

    Kur'yanova, E V; Zhukova, Yu D; Teplyi, D L

    2017-07-01

    The effects of intraperitoneal DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, a noradrenergic neurotoxin) and maprotiline (an inhibitor of norepinephrine reuptake in synapses) on spectral components of heart rhythm variability were examined in outbred male and female rats treated with these agents in daily doses of 10 mg/kg for 3 days. At rest, DSP-4 elevated LF and VLF spectral components in male and female rats. Maprotiline elevated LF and VLF components in males at rest, increased HR and reduced all spectral components in resting females. Stress against the background of DSP-4 treatment sharply increased heart rate and reduced the powers of all spectral components (especially LF and VLF components). In maprotiline-treated rats, stress increased the powers of LF and VLF components. Thus, the central noradrenergic system participates in the formation of LF and VLF spectral components of heart rate variability at rest and especially during stressful stimulation, which can determine the phasic character of changes in the heart rate variability observed in stressed organism.

  18. Rates and probable causes of freshwater tidal marsh failure, Potomac River Estuary, Northern Virginia, USA

    USGS Publications Warehouse

    Litwin, Ronald J.; Smoot, Joseph P.; Pavich, Milan J.; Markewich, Helaine Walsh; Oberg, Erik T.; Steury, Brent W.; Helwig, Ben; Santucci, Vincent L.; Sanders, Geoffrey

    2013-01-01

    Dyke Marsh, a distal tidal marsh along the Potomac River estuary, is diminishing rapidly in areal extent. This study documents Dyke Marsh erosion rates from the early-1860s to the present during pre-mining, mining, and post-mining phases. From the late-1930s to the mid-1970s, Dyke Marsh and the adjacent shallow riverbottom were mined for gravel, resulting in a ~55 % initial loss of area. Marsh loss continued during the post-mining phase (1976–2012). Causes of post-mining loss were unknown, but were thought to include Potomac River flooding. Post-mining areal-erosion rates increased from 0.138 ha yr−1 (~0.37 ac yr−1) to 0.516 ha yr−1(~1.67 ac yr−1), and shoreline-erosion rates increased from 0.76 m yr−1 (~2.5 ft yr−1) to 2.60 m yr−1 (~8.5 ft yr−1). Results suggest the accelerating post-mining erosion reflects a process-driven feedback loop, enabled by the marsh's severely-altered geomorphic and hydrologic baseline system; the primary post-mining degradation process is wave-induced erosion from northbound cyclonic storms. Dyke Marsh erosion rates are now comparable to, or exceed, rates for proximal coastal marshes in the same region. Persistent and accelerated erosion of marshland long after cessation of mining illustrates the long-term, and potentially devastating, effects that temporally-restricted, anthropogenic destabilization can have on estuarine marsh systems.

  19. Effect of Visit-to-Visit Variation of Heart Rate and Systolic Blood Pressure on Outcomes in Chronic Systolic Heart Failure: Results From the Systolic Heart Failure Treatment With the If Inhibitor Ivabradine Trial (SHIFT) Trial.

    PubMed

    Böhm, Michael; Robertson, Michele; Borer, Jeffrey; Ford, Ian; Komajda, Michel; Mahfoud, Felix; Ewen, Sebastian; Swedberg, Karl; Tavazzi, Luigi

    2016-02-12

    Elevated resting heart rate (HR) and low systolic blood pressure (SBP) are related to poor outcomes in heart failure (HF). The association between visit-to-visit variation in SBP and HR and risk in HF is unknown. In Systolic Heart Failure Treatment with the If inhibitor ivabradine Trial (SHIFT) patients, we evaluated relationships between mean HR, mean SBP, and visit-to-visit variations (coefficient of variation [CV]=SD/mean×100%) in SBP and HR (SBP-CV and HR-CV, respectively) and primary composite endpoint (cardiovascular mortality or HF hospitalization), its components, all-cause mortality, and all-cause hospitalization. High HR and low SBP were closely associated with risk for primary endpoint, all-cause mortality, and HF hospitalization. The highest number of primary endpoint events occurred in the highest HR tertile (38.8% vs 16.4% lowest tertile; P<0.001). For HR-CV, patients at highest risk were those in the lowest tertile. Patients in the lowest thirds of mean SBP and SBP-CV had the highest risk. The combination of high HR and low HR-CV had an additive deleterious effect on risk, as did that of low SBP and low SBP-CV. Ivabradine reduced mean HR and increased HR-CV, and increased SBP and SBP-CV slightly. Beyond high HR and low SBP, low HR-CV and low SBP-CV are predictors of cardiovascular outcomes with additive effects on risk in HF, but with an unknown effect size. Beyond HR reduction, ivabradine increases HR-CV. Low visit-to-visit variation of HR and SBP might signal risk of cardiovascular outcomes in systolic HF. URL: http://www.isrctn.com/. Unique identifier: ISRCTN70429960. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  20. Increased Failure Rate of Modified Double Arthrodesis Compared With Triple Arthrodesis for Rigid Pes Planovalgus.

    PubMed

    Burrus, M Tyrrell; Werner, Brian C; Carr, James B; Perumal, Venkat; Park, Joseph S

    For rigid pes planovalgus deformities, modified double and triple arthrodeses have had high union rates and subjective outcomes reported. Increased rates of talonavicular nonunions after modified double arthrodesis have led to concern regarding this procedure. A retrospective medical record review was performed of patients who had undergone either a modified double (n = 9) or triple (n = 7) arthrodesis for stage 3 pes planovalgus deformity. Radiographs were reviewed for hindfoot alignment, bony union, and hardware failure. Data from questionnaires, including the Foot and Ankle Ability Measure and the Foot and Ankle Outcome Score, were obtained. No significant differences were found between the cohorts in terms of preoperative radiographic parameters or patient characteristics. The modified double arthrodesis cohort demonstrated a nonunion rate of 44% (4 of 9), but the triple arthrodesis cohort had a 0% (0 of 7) nonunion rate (p = .042). The Foot and Ankle Ability Measure activities of daily living, Foot and Ankle Outcome Score activities of daily living, and Foot and Ankle Outcome Score quality of life scores were significantly worse for the modified double arthrodesis than for the triple arthrodesis group. For patients with stage 3 pes planovalgus, modified double arthrodesis resulted in significantly greater rates of nonunion and incomplete union, with significantly inferior subjective outcome scores compared with triple arthrodesis for the same indication. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  1. Determination of crack morphology parameters from service failures for leak-rate analyses

    SciTech Connect

    Wilkowski, G.; Ghadiali, N.; Paul, D.

    1997-04-01

    In leak-rate analyses described in the literature, the crack morphology parameters are typically not well agreed upon by different investigators. This paper presents results on a review of crack morphology parameters determined from examination of service induced cracks. Service induced cracks were found to have a much more tortuous flow path than laboratory induced cracks due to crack branching associated with the service induced cracks. Several new parameters such as local and global surface roughnesses, as well as local and global number of turns were identified. The effect of each of these parameters are dependent on the crack-opening displacement. Additionally, the crack path is typically assumed to be straight through the pipe thickness, but the service data show that the flow path can be longer due to the crack following a fusion line, and/or the number of turns, where the number of turns in the past were included as a pressure drop term due to the turns, but not the longer flow path length. These parameters were statistically evaluated for fatigue cracks in air, corrosion-fatigue, IGSCC, and thermal fatigue cracks. A refined version of the SQUIRT leak-rate code was developed to account for these variables. Sample calculations are provided in this paper that show how the crack size can vary for a given leak rate and the statistical variation of the crack morphology parameters.

  2. Resting Heart Rate as Predictor for Left Ventricular Dysfunction and Heart Failure: The Multi-Ethnic Study of Atherosclerosis

    PubMed Central

    Opdahl, Anders; Venkatesh, Bharath Ambale; Fernandes, Veronica R. S.; Wu, Colin O.; Nasir, Khurram; Choi, Eui-Young; Almeida, Andre L. C.; Rosen, Boaz; Carvalho, Benilton; Edvardsen, Thor; Bluemke, David A.; Lima, Joao A. C.

    2014-01-01

    OBJECTIVE To investigate the relationship between baseline resting heart rate and incidence of heart failure (HF) and global and regional left ventricular (LV) dysfunction. BACKGROUND The association of resting heart rate to HF and LV function is not well described in an asymptomatic multi-ethnic population. METHODS Participants in the Multi-Ethnic Study of Atherosclerosis had resting heart rate measured at inclusion. Incident HF was registered (n=176) during follow-up (median 7 years) in those who underwent cardiac MRI (n=5000). Changes in ejection fraction (ΔEF) and peak circumferential strain (Δεcc) were measured as markers of developing global and regional LV dysfunction in 1056 participants imaged at baseline and 5 years later. Time to HF (Cox model) and Δεcc and ΔEF (multiple linear regression models) were adjusted for demographics, traditional cardiovascular risk factors, calcium score, LV end-diastolic volume and mass in addition to resting heart rate. RESULTS Cox analysis demonstrated that for 1 bpm increase in resting heart rate there was a 4% greater adjusted relative risk for incident HF (Hazard Ratio: 1.04 (1.02, 1.06 (95% CI); P<0.001). Adjusted multiple regression models demonstrated that resting heart rate was positively associated with deteriorating εcc and decrease in EF, even in analyses when all coronary heart disease events were excluded from the model. CONCLUSION Elevated resting heart rate is associated with increased risk for incident HF in asymptomatic participants in MESA. Higher heart rate is related to development of regional and global LV dysfunction independent of subclinical atherosclerosis and coronary heart disease. PMID:24412444

  3. Resting heart rate as predictor for left ventricular dysfunction and heart failure: MESA (Multi-Ethnic Study of Atherosclerosis).

    PubMed

    Opdahl, Anders; Ambale Venkatesh, Bharath; Fernandes, Veronica R S; Wu, Colin O; Nasir, Khurram; Choi, Eui-Young; Almeida, Andre L C; Rosen, Boaz; Carvalho, Benilton; Edvardsen, Thor; Bluemke, David A; Lima, João A C

    2014-04-01

    The objective of this study was to investigate the relationship between baseline resting heart rate and incidence of heart failure (HF) and global and regional left ventricular (LV) dysfunction. The association of resting heart rate to HF and LV function has not been well described in an asymptomatic multi-ethnic population. Resting heart rate was measured in participants in the MESA (Multi-Ethnic Study of Atherosclerosis) trial at inclusion. Incident HF was registered (n = 176) during follow-up (median 7 years) in those who underwent cardiac magnetic resonance imaging (n = 5,000). Changes in ejection fraction (ΔEF) and peak circumferential strain (Δεcc) were measured as markers of developing global and regional LV dysfunction in 1,056 participants imaged at baseline and 5 years later. Time to HF (Cox model) and Δεcc and ΔEF (multiple linear regression models) were adjusted for demographics, traditional cardiovascular risk factors, calcium score, LV end-diastolic volume, and mass in addition to resting heart rate. Cox analysis demonstrated that for 1 beat/min increase in resting heart rate, there was a 4% greater adjusted relative risk for incident HF (hazard ratio: 1.04; 95% CI: 1.02 to 1.06; p < 0.001). Adjusted multiple regression models demonstrated that resting heart rate was positively associated with deteriorating εcc and decrease in EF, even when all coronary heart disease events were excluded from the model. Elevated resting heart rate was associated with increased risk for incident HF in asymptomatic participants in the MESA trial. Higher heart rate was related to development of regional and global LV dysfunction independent of subclinical atherosclerosis and coronary heart disease. (Multi-Ethnic Study of Atherosclerosis [MESA]; NCT00005487). Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  4. Prevalence of vaccination rates in systolic heart failure: a prospective study of 549 patients by age, race, ethnicity, and sex in a heart failure disease management program.

    PubMed

    Hebert, Kathy; Marzouka, George; Arcement, Lee; Julian, Elyse; Cortazar, Frank; Dias, Andre; Tamariz, Leonardo

    2010-01-01

    Healthy People 2010 aims at immunizing 60% of high-risk adults annually against influenza and once against pneumococcal disease. The aim of this study was to evaluate the use of a standardized approach to improve vaccination rates in patients with heart failure (HF); to determine whether disparities exist based on age, race, ethnicity, or sex at baseline and follow-up; and to evaluate the impact of clinical variables on the odds of being vaccinated. A prospective study of 549 indigent patients enrolled in a systolic HF disease management program (HFDMP) began enrollment from August 2007 to January 2009 at Jackson Memorial Hospital. Patients were interviewed at their initial visit for immunization status; those without vaccinations were offered the vaccines. Prevalence of vaccination (POV) for influenza and pneumococcal disease was obtained at baseline and at follow-up. The odds ratio for being vaccinated was calculated using logistic regression. The study population comprised mostly Hispanic (56%), black (37%), and male (70%) patients, with a mean age of 56 ± 12 years and a mean ejection fraction of 25% ± 10%. The initial POV for both was 22% at baseline. At follow-up, POV improved to 60.5%. Of those not vaccinated at baseline, 17.5% refused vaccination. Odds ratios at baseline for age, race/ethnicity, and sex were 0.99 (P=.99), 0.63 (P=.08), and 0.62 (P=.14), respectively. These did not change significantly at follow-up. Prevalence of vaccination in our cohort was low. Enrollment into the HFDMP improved immunization prevalence without creating age, race, ethnicity, or sex disparities. © 2010 Wiley Periodicals, Inc.

  5. Effects of age and loading rate on equine cortical bone failure.

    PubMed

    Kulin, Robb M; Jiang, Fengchun; Vecchio, Kenneth S

    2011-01-01

    Although clinical bone fractures occur predominantly under impact loading (as occurs during sporting accidents, falls, high-speed impacts or other catastrophic events), experimentally validated studies on the dynamic fracture behavior of bone, at the loading rates associated with such events, remain limited. In this study, a series of tests were performed on femoral specimens obtained post-mortem from equine donors ranging in age from 6 months to 28 years. Fracture toughness and compressive tests were performed under both quasi-static and dynamic loading conditions in order to determine the effects of loading rate and age on the mechanical behavior of the cortical bone. Fracture toughness experiments were performed using a four-point bending geometry on single and double-notch specimens in order to measure fracture toughness, as well as observe differences in crack initiation between dynamic and quasi-static experiments. Compressive properties were measured on bone loaded parallel and transverse to the osteonal growth direction. Fracture propagation was then analyzed using scanning electron and scanning confocal microscopy to observe the effects of microstructural toughening mechanisms at different strain rates. Specimens from each horse were also analyzed for dry, wet and mineral densities, as well as weight percent mineral, in order to investigate possible influences of composition on mechanical behavior. Results indicate that bone has a higher compressive strength, but lower fracture toughness when tested dynamically as compared to quasi-static experiments. Fracture toughness also tends to decrease with age when measured quasi-statically, but shows little change with age under dynamic loading conditions, where brittle "cleavage-like" fracture behavior dominates.

  6. A pilot rating scale for evaluating failure transients in electronic flight control systems

    NASA Technical Reports Server (NTRS)

    Hindson, William S.; Schroeder, Jeffery A.; Eshow, Michelle M.

    1990-01-01

    A pilot rating scale was developed to describe the effects of transients in helicopter flight-control systems on safety-of-flight and on pilot recovery action. The scale was applied to the evaluation of hardovers that could potentially occur in the digital flight-control system being designed for a variable-stability UH-60A research helicopter. Tests were conducted in a large moving-base simulator and in flight. The results of the investigation were combined with existing airworthiness criteria to determine quantitative reliability design goals for the control system.

  7. A pilot rating scale for evaluating failure transients in electronic flight control systems

    NASA Technical Reports Server (NTRS)

    Hindson, William S.; Schroeder, Jeffery A.; Eshow, Michelle M.

    1990-01-01

    A pilot rating scale was developed to describe the effects of transients in helicopter flight-control systems on safety-of-flight and on pilot recovery action. The scale was applied to the evaluation of hardovers that could potentially occur in the digital flight-control system being designed for a variable-stability UH-60A research helicopter. Tests were conducted in a large moving-base simulator and in flight. The results of the investigation were combined with existing airworthiness criteria to determine quantitative reliability design goals for the control system.

  8. The Influence of Evidence-Based Surgical Indications and Techniques on Failure Rates After Arthroscopic Shoulder Stabilization in the Contact or Collision Athlete With Anterior Shoulder Instability.

    PubMed

    Leroux, Timothy S; Saltzman, Bryan M; Meyer, Maximilian; Frank, Rachel M; Bach, Bernard R; Cole, Brian J; Romeo, Anthony A; Verma, Nikhil N

    2017-04-01

    It has been reported that arthroscopic shoulder stabilization yields higher rates of failure in contact or collision athletes as compared with open shoulder stabilization; however, this is largely based upon studies that do not employ modern, evidence-based surgical indications and techniques for arthroscopic shoulder stabilization. To (1) determine the pooled failure rate across all studies reporting failure after primary arthroscopic shoulder stabilization for anterior shoulder instability in contact or collision athletes and (2) stratify failure rates according to studies that use evidence-based surgical indications and techniques. Systematic review. A review of PubMed, Medline, and Embase was performed to identify all clinical studies with a minimum of 1-year follow-up that reported failure rates after arthroscopic shoulder stabilization for anterior shoulder instability in contact or collision athletes. Data pertaining to patient demographics, clinical and radiographic preoperative assessment, surgical indications, surgical technique, rehabilitation, and outcome were collected from each included study. An overall failure rate was determined across all included studies. After this, a secondary literature review was performed to identify factors related to patient selection and surgical technique that significantly influence failure after primary arthroscopic shoulder stabilization. Failure rates were then determined among included studies that used these evidence-based indications and techniques. Overall, 26 studies reporting on 779 contact or collision athletes met the inclusion criteria. The mean patient age was 19.9 years, 90.3% were male, and the most common sport was rugby. There was considerable variability in the reporting of patient demographics, preoperative assessment, surgical indications, surgical technique, and patient outcomes. Across all included studies, the pooled failure rate after arthroscopic shoulder stabilization in the contact or

  9. Failure modes and effects analysis in image-guided high-dose-rate brachytherapy: Quality control optimization to reduce errors in treatment volume.

    PubMed

    Wadi-Ramahi, Shada; Alnajjar, Waleed; Mahmood, Rana; Jastaniyah, Noha; Moftah, Belal

    2016-01-01

    Analyze the inputs which cause treatment to the wrong volume in high-dose-rate brachytherapy (HDRB), with emphasis on imaging role during implant, planning, and treatment verification. The end purpose is to compare our current practice to the findings of the study and apply changes where necessary. Failure mode and effects analysis was used to study the failure pathways for treating the wrong volume in HDRB. The role of imaging and personnel was emphasized, and subcategories were formed. A quality assurance procedure is proposed for each high-scoring failure mode (FM). Forty FMs were found that lead to treating the wrong volume. Of these, 73% were human failures, 20% were machine failures, and 7% were procedural/guideline failures. The use of imaging was found to resolve 85% of the FMs. We also noted that imaging processes were under used in current practice of HDRB especially in pretreatment verification. Twelve FMs (30%) scored the highest, and for each one of them, we propose clinical/practical solutions that could be applied to reduce the risk by increasing detectability. This work resulted in two conclusions: the role of imaging in improving failure detection and the emphasized role of human-based failures. The majority of FMs are human failures, and imaging increased the ability to detect 85% of all FMs. We proposed quality assurance practices for each high-scoring FM and have implemented some of them in our own practice. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  10. Internal fixation of radiation-induced pathological fractures of the femur has a high rate of failure.

    PubMed

    Sternheim, A; Saidi, K; Lochab, J; O'Donnell, P W; Eward, W C; Griffin, A; Wunder, J S; Ferguson, P

    2013-08-01

    We investigated the clinical outcome of internal fixation for pathological fracture of the femur after primary excision of a soft-tissue sarcoma that had been treated with adjuvant radiotherapy. A review of our database identified 22 radiation-induced fractures of the femur in 22 patients (seven men, 15 women). We noted the mechanism of injury, fracture pattern and any complications after internal fixation, including nonunion, hardware failure, secondary fracture or deep infection. The mean age of the patients at primary excision of the tumour was 58.3 years (39 to 86). The mean time from primary excision to fracture was 73.2 months (2 to 195). The mean follow-up after fracture fixation was 65.9 months (12 to 205). Complications occurred in 19 patients (86%). Nonunion developed in 18 patients (82%), of whom 11 had a radiological nonunion at 12 months, five a nonunion and hardware failure and two an infected nonunion. One patient developed a second radiation-associated fracture of the femur after internal fixation and union of the initial fracture. A total of 13 patients (59%) underwent 24 revision operations. Internal fixation of a pathological fracture of the femur after radiotherapy for a soft-tissue sarcoma has an extremely high rate of complication and requires specialist attention.

  11. [Applying healthcare failure mode and effect analysis to improve the surgical specimen transportation process and rejection rate].

    PubMed

    Hu, Pao-Hsueh; Hu, Hsiao-Chen; Huang, Hui-Ju; Chao, Hui-Lin; Lei, Ei-Fang

    2014-04-01

    Because surgical pathology specimens are crucial to the diagnosis and treatment of disease, it is critical that they be collected and transported safely and securely. Due to recent near-miss events in our department, we used the healthcare failure model and effect analysis to identify 14 potential perils in the specimen collection and transportation process. Improvement and prevention strategies were developed accordingly to improve quality of care. Using health care failure mode and effect analysis (HFMEA) may improve the surgical specimen transportation process and reduce the rate of surgical specimen rejection. Rectify standard operating procedures for surgical pathology specimen collection and transportation. Create educational videos and posters. Rectify methods of specimen verification. Organize and create an online and instantaneous management system for specimen tracking and specimen rejection. Implementation of the new surgical specimen transportation process effectively eliminated the 14 identified potential perils. In addition, the specimen rejection fell from 0.86% to 0.03%. This project was applied to improve the specimen transportation process, enhance interdisciplinary cooperation, and improve the patient-centered healthcare system. The creation and implementation of an online information system significantly facilitates specimen tracking, hospital cost reductions, and patient safety improvements. The success in our department is currently being replicated across all departments in our hospital that transport specimens. Our experience and strategy may be applied to inter-hospital specimen transportation in the future.

  12. Numerical analysis of high strain rate failure of electro-magnetically loaded steel sheets

    NASA Astrophysics Data System (ADS)

    Erice, Borja; Mohr, Dirk

    2015-09-01

    Electro-magnetic forces provide a potentially power full means in designing dynamic experiments with active control of the loading conditions. This article deals with the development of computational models to simulate the thermo-mechanical response of electro-magnetically loaded metallic structures. The model assumes linear electromagnetic constitutive equations and time-independent electric induction to estimate the Joule heating and the Lorentz forces. The latter are then taken into account when evaluating stress equilibrium. A thermo-visco-plastic model with Johnson-Cook type of temperature and strain rate dependence and combined Swift-Voce hardening is used to evaluate the material's thermo-mechanical response. As a first application, the model is used to analyse the effect of electro-magnetic loading on the ductility of advanced high strength steels.

  13. Unrecognized high brachial artery bifurcation is associated with higher rate of dialysis access failure.

    PubMed

    Kirksey, Lee

    2011-01-01

    A thorough consideration of all factors contributing to successful dialysis access creation is necessary to achieve optimal outcomes. A high bifurcation of the brachial artery (brachioradial variant) occurs in greater than 20% of patients. Dialysis access was created in 22 limbs with this variant--15 fistula, and 7 prosthetic grafts. Nonmaturation occurred in 33% of fistula. Early thromboses occurred in 29% of prosthetic bridge grafts. In this experience, the brachioradial variant is associated with a relatively higher rate of fistula nonmaturation and prosthetic graft thromboses. These findings reinforce the critical role of preoperative imaging studies in dialysis access creation. A sound algorithm for the surgical management of the brachioradial variation facilitates decision making and will improve dialysis access outcomes.

  14. Twenty-four-hour heart rate lowering with ivabradine in chronic heart failure: insights from the SHIFT Holter substudy.

    PubMed

    Böhm, Michael; Borer, Jeffrey S; Camm, John; Ford, Ian; Lloyd, Suzanne M; Komajda, Michel; Tavazzi, Luigi; Talajic, Mario; Lainscak, Mitja; Reil, Jan-Christian; Ukena, Christian; Swedberg, Karl

    2015-05-01

    Analysis of 24-h Holter recordings was a pre-specified substudy of SHIFT (Systolic Heart Failure Treatment with the If Inhibitor Ivabradine Trial) for exploring the heart rhythm safety of ivabradine and to determine effects of ivabradine on 24-h, daytime, and night-time heart rate (HR) compared with resting office HR. The 24-h Holter monitoring was performed at baseline and 8 months after randomization to ivabradine (n = 298) or matching placebo (n = 304) titrated maximally to 7.5 mg b.i.d. in patients with baseline HR ≥70 b.p.m. Patients received guideline-based optimized heart failure therapy including ACE inhibitors and/or ARBs in 93% and beta-blockers at maximally tolerated doses in 93%. After 8 months, HR over 24 h decreased by 9.5 ± 10.0 b.p.m. with ivabradine, from 75.4 ± 10.3 b.p.m. (P < 0.0001), and by 1.2 ± 8.9 b.p.m. with placebo, from 74.8 ± 9.7 b.p.m. (P < 0.0001 for difference vs. ivabradine). HR reduction with ivabradine was similar in resting office and in 24-h, awake, and asleep recordings, with beneficial effects on HR variability and no meaningful increases in supraventricular or ventricular arrhythmias. At 8 months, 21.3% on ivabradine vs. 8.5% on placebo had ≥1 episode of HR <40 b.p.m. (P < 0.0001). No episode of HR <30 b.p.m. was recorded; 3 (1.2%) patients had RR intervals >2.5 s on ivabradine vs. 4 (1.6%) patients on placebo. No RR intervals >3 s were identified in patients taking ivabradine. Ivabradine safely and significantly lowers HR and improves HR variability in patients with systolic heart failure, without inducing significant bradycardia, ventricular arrhythmias, or supraventricular arrhythmias. © 2015 The Authors. European Journal of Heart Failure © 2015 European Society of Cardiology.

  15. Plastic flow, inferred strength, and incipient failure in BCC metals at high pressures, strains, and strain rates

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook

    2013-06-01

    We present our extensive experimental results from the Omega laser to test models of high pressure, high strain rate strength at ~1 Mbar peak pressures, strains >10%, and strain rates of ~107 s-1 in Ta, V, and Fe, using plastic flows driven by the Rayleigh-Taylor instability. The observed time evolution of the plastic deformation is compared with 2D simulations incorporating a strength model. This methodology allows average values of strength at peak pressure and peak strain rate conditions to be inferred. The observed values of strength are typically factors of 5-10 higher than ambient strength, with contributions coming from pressure hardening (via the shear modulus), and strain rate hardening. For Fe, there is the added contribution from the alpha-epsilon phase transition. Ta has been studied as a function of grain size, and at the high strain rates and short durations of the experiments, no grain size dependence was observed; the observed deformation and inferred strength were independent of grain size. Both Ta and V have been driven to large enough strains that incipient failure (softening) has been observed. Both the Ta and V experiments were compared favorably with multiscale strength models, with the conclusion that the Ta deformation was in the thermal activation regime, whereas the V deformation was in the phonon drag regime. Finally, preliminary results of new iron RT strength experiments done at ~1 Mbar pressures, and ~107 s-1 strain rates, well beyond the alpha-epsilon phase transition, will be given. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  16. Tape Versus Suture in Arthroscopic Rotator Cuff Repair: Biomechanical Analysis and Assessment of Failure Rates at 6 Months.

    PubMed

    Liu, Rui Wen; Lam, Patrick Hong; Shepherd, Henry M; Murrell, George A C

    2017-04-01

    Rotator cuff retears after surgical repair are associated with poorer subjective and objectives clinical outcomes than intact repairs. The aims of this study were to (1) examine the biomechanical differences between rotator cuff repair using No. 2 suture and tape in an ovine model and (2) compare early clinical outcomes between patients who had rotator cuff repair with tape and patients who had repair with No. 2 suture. Controlled laboratory study and cohort study; Level of evidence, 3. Biomechanical testing of footprint contact pressure and load to failure were conducted with 16 ovine shoulders using a tension band repair technique with 2 different types of sutures (No. 2 suture [FiberWire; Arthrex] and tape [FiberTape; Arthrex]) with the same knotless anchor system. A retrospective study of 150 consecutive patients (tape, n = 50; suture, n = 100) who underwent arthroscopic rotator cuff repair by a single surgeon with tear size larger than 1.5 × 1 cm was conducted. Ultrasound was used to evaluate the repair integrity at 6 months postsurgery. Rotator cuff repair using tape had greater footprint contact pressure (mean ± standard error of the mean, 0.33 ± 0.03 vs 0.11 ± 0.3 MPa; P < .0001) compared with repair using No. 2 sutures at 0° abduction with a 30-N load applied across the repaired tendon. The ultimate failure load of the tape repair was greater than that for suture repair (217 ± 28 vs 144 ± 14 N; P < .05). The retear rate was similar between the tape (16%; 8/50) and suture groups (17%; 17/100). Rotator cuff repair with the wider tape compared with No. 2 suture did not affect the retear rate at 6 months postsurgery, despite having superior biomechanical properties.

  17. Rates of Reconstruction Failure in Patients Undergoing Immediate Reconstruction With Tissue Expanders and/or Implants and Postmastectomy Radiation Therapy.

    PubMed

    Fowble, Barbara; Park, Catherine; Wang, Frederick; Peled, Anne; Alvarado, Michael; Ewing, Cheryl; Esserman, Laura; Foster, Robert; Sbitany, Hani; Hanlon, Alex

    2015-07-01

    Mastectomy rates for breast cancer have increased, with a parallel increase in immediate reconstruction. For some women, tissue expander and implant (TE/I) reconstruction is the preferred or sole option. This retrospective study examined the rate of TE/I reconstruction failure (ie, removal of the TE or I with the inability to replace it resulting in no final reconstruction or autologous tissue reconstruction) in patients receiving postmastectomy radiation therapy (PMRT). Between 2004 and 2012, 99 women had skin-sparing mastectomies (SSM) or total nipple/areolar skin-sparing mastectomies (TSSM) with immediate TE/I reconstruction and PMRT for pathologic stage II to III breast cancer. Ninety-seven percent had chemotherapy (doxorubicin and taxane-based), 22% underwent targeted therapies, and 78% had endocrine therapy. Radiation consisted of 5000 cGy given in 180 to 200 cGy to the reconstructed breast with or without treatment to the supraclavicular nodes. Median follow-up was 3.8 years. Total TE/I failure was 18% (12% without final reconstruction, 6% converted to autologous reconstruction). In univariate analysis, the strongest predictor of reconstruction failure (RF) was absence of total TE/I coverage (acellular dermal matrix and/or serratus muscle) at the time of radiation. RF occurred in 32.5% of patients without total coverage compared to 9% with coverage (P=.0069). For women with total coverage, the location of the mastectomy scar in the inframammary fold region was associated with higher RF (19% vs 0%, P=.0189). In multivariate analysis, weight was a significant factor for RF, with lower weight associated with a higher RF. Weight appeared to be a surrogate for the interaction of total coverage, thin skin flaps, interval to exchange, and location of the mastectomy scar. RFs in patients receiving PMRT were lowered with total TE/I coverage at the time of radiation by avoiding inframammary fold incisions and with a preferred interval of 6 months to exchange

  18. Influenza vaccination coverage rate in children: reasons for a failure and how to go forward.

    PubMed

    Olivier, Catherine Weil

    2012-01-01

    Based on an increasingly extensive literature expressing the large interest in the field, this paper gives an overview of different aspects of influenza prevention in children. It relies on paradoxes. First, the heaviest part of the burden is well demonstrated in the youngest infants by numerous epidemiological data elsewhere. On the contrary, with older children, the prevention by influenza vaccines is more efficacious-without notable side effects. Second, the available TIV vaccines are 60 years old and the requests of registration and regulation of vaccines have evolved. There is a specific need in children: it is time to re-discuss the pragmatic utilization of influenza vaccines (full dose in the youngest patient? More flexibility regarding the interval between the two required doses in vaccine-naïve children), and to change from a compassionate use to a targeted research and adapted vaccines considering the limits of TIV in the youngest children. Third, influenza virus transmission is the highest in children in semi-close communities (day-care centers, schools), diffusing to households and more largely to the population. A restricted policy on high risk groups (roughly 10% in a pediatric population, all medical conditions including asthma, for whom influenza vaccine coverage is a 15-75% range) is far below the estimated threshold of 45% coverage rate to limit the virus circulation by an indirect impact during seasonal epidemics. Fourth, public health decisions in the vaccination field are usually taken from top to bottom. The pandemic A/H1N1 has toughly demonstrated that "forgetting" about the perception and expectations of the public and the parents nearly created conflicts and at least a strong resistance impeding the quality of a program worked on for a long time ahead. Fifth, and not the least, HCPs are pivotal in influenza vaccination mostly trusted by the parents. Too often, they are not backed by a national and clear support and they need to reinforce

  19. Effect of fluoridated paste on the failure rate of precoated brackets bonded with self-etching primer: a prospective split-mouth study.

    PubMed

    Talic, Nabeel F

    2011-10-01

    The aim of this prospective randomized clinical trial was to determine the effect of using fluoridated paste (Dentsply, York, Pa) compared with plain pumice (Ortho Technology, Tampa, Fla) on the clinical bond failure rates of precoated brackets bonded with self-etching primer. A split-mouth technique was used. The teeth in the maxillary right and mandibular left quadrants were prepared with a fluoridated paste only, and the teeth in the maxillary left and mandibular right quadrants were prepared with plain pumice before bonding the precoated brackets. A total of 627 brackets in 34 orthodontic patients (20 female, 14 male) were included in this study; 315 brackets were bonded after pumice treatment, and 312 were bonded after paste treatment. The patients were followed for 6 months to determine the rates of bracket failure. The overall failure rate was 8%. The failure rates for pumice and paste were 4.8% and 11.2%, respectively. The McNemar test showed a statistically significant difference between the 2 groups. Based on tooth type, the failure rate of the maxillary canine and the mandibular central incisor brackets were significantly different for paste and pumice. There was also a difference in the survival rates of the brackets in both groups. Preparation of the enamel surface with fluoridated paste before bonding with self-etching primer is not recommended. However, the use of plain pumice is recommended, even if it is time-consuming. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  20. Learning to drive: learners' self-reported cognitive failure level predicts driving instructor's observation rating of driving performance.

    PubMed

    Elfering, Achim; Ruppen, Veronique; Grebner, Simone

    2013-01-01

    Evidence increases that cognitive failure may be used to screen for drivers at risk. Until now, most studies have relied on driving learners. This exploratory pilot study examines self-report of cognitive failure in driving beginners and error during real driving as observed by driving instructors. Forty-two driving learners of 14 driving instructors filled out a work-related cognitive failure questionnaire. Driving instructors observed driving errors during the next driving lesson. In multiple linear regression analysis, driving errors were regressed on cognitive failure with the number of driving lessons as an estimator of driving experience controlled. Higher cognitive failure predicted more driving errors (p < .01) when age, gender and driving experience were controlled in analysis. Cognitive failure was significantly associated with observed driving errors. Systematic research on cognitive failure in driving beginners is recommended.

  1. Factors affecting evaporation rates of tear film components measured in vitro.

    PubMed

    Borchman, Douglas; Foulks, Gary N; Yappert, Marta C; Mathews, Jonathan; Leake, Kim; Bell, Jim

    2009-01-01

    With increasing age and in patients affected with dry-eye symptoms, the human tear film becomes more unstable and exhibits shorter tear break-up times. We examined whether the inclusion of proteins and lipids to water affected the evaporation rates measured in vitro and could account for the lower rates reported previously from in vivo measurements. The impact of temperature, air flow, and humidity on the evaporation rate of tears was measured in vitro. Lipid-protein interactions were measured using fluorescence spectroscopy and in vitro rates of evaporation were performed gravimetrically. Human reflex tears evaporated at a rate similar to that of water. A temperature increase from 25 degrees C to 34 degrees C caused a threefold increase in the evaporation rates of tears in still air. Further increases were observed under a current of dry air. Wax, mucin, lysozyme, or beta-lactoglobulin did not influence significantly the rates of evaporation measured in vitro. In contrast, lipid layered on the surface resulted in a 23% decrease in the rates. Environmental factors affect evaporation rates significantly and should be carefully controlled when performing in vivo measurements. The presence of a lipid layer lowers evaporation rates. The significantly lower rates of evaporation of tears measured in vivo suggest that with the lipid layer intact, the high reserve capacity of the lacrimal gland to provide both unstimulated and stimulated tear flow is more than enough to compensate for evaporative loss. However, with dry eye, increased rates of evaporation and decreased lacrimal tear flow could result in decreased break-up times.

  2. Measuring kinetic rate constants of multiple-component reactions with optical biosensors.

    PubMed

    Edwards, David A; Evans, Ryan M; Li, Wenbin

    2017-09-15

    One may measure the kinetic rate constants associated with biochemical reactions using an optical biosensor: an instrument in which ligand molecules are convected through a flow cell over a surface to which receptors are immobilized. If there are multiple reactants, one is faced with the problem of fitting multiple kinetic rate constants to one signal, since data from all of the reacting species is lumped together. Even in the presence of ambiguous data, one may use a series of experiments to accurately determine the rate constants. Moreover, the true set of rate constants may be identified by either postprocessing the signals or adjusting the ligand inflow concentrations. Published by Elsevier Inc.

  3. Which components of heart failure programmes are effective? A systematic review and meta-analysis of the outcomes of structured telephone support or telemonitoring as the primary component of chronic heart failure management in 8323 patients: Abridged Cochrane Review.

    PubMed

    Inglis, Sally C; Clark, Robyn A; McAlister, Finlay A; Stewart, Simon; Cleland, John G F

    2011-09-01

    Telemonitoring (TM) and structured telephone support (STS) have the potential to deliver specialized management to more patients with chronic heart failure (CHF), but their efficacy is still to be proven. The aim of this meta-analysis was to review randomized controlled trials (RCTs) of TM or STS for all-cause mortality and all-cause and CHF-related hospitalizations in patients with CHF, as a non-invasive remote model of a specialized disease-management intervention. We searched all relevant electronic databases and search engines, hand-searched bibliographies of relevant studies, systematic reviews, and meeting abstracts. Two reviewers independently extracted all data. Randomized controlled trials comparing TM or STS to usual care in patients with CHF were included. Studies that included intensified management with additional home or clinic-visits were excluded. Primary outcomes (mortality and hospitalizations) were analysed; secondary outcomes (cost, length of stay, and quality of life) were tabulated. Thirty RCTs of STS and TM were identified (25 peer-reviewed publications (n= 8323) and five abstracts (n= 1482)). Of the 25 peer-reviewed studies, 11 evaluated TM (2710 participants), 16 evaluated STS (5613 participants) with two testing both STS and TM in separate intervention arms compared with usual care. Telemonitoring reduced all-cause mortality {risk ratio (RR) 0.66 [95% confidence interval (CI) 0.54-0.81], P< 0.0001 }and STS showed a similar, but non-significant trend [RR 0.88 (95% CI 0.76-1.01), P= 0.08]. Both TM [RR 0.79 (95% CI 0.67-0.94), P= 0.008], and STS [RR 0.77 (95% CI 0.68-0.87), P< 0.0001] reduced CHF-related hospitalizations. Both interventions improved quality of life, reduced costs, and were acceptable to patients. Improvements in prescribing, patient-knowledge and self-care, and functional class were observed. Telemonitoring and STS both appear effective interventions to improve outcomes in patients with CHF. Systematic Review Number: Cochrane

  4. Correlation analysis between the rate of respiration in the root and the active components in licorice (Glycyrrhiza uralensis).

    PubMed

    Guo, Peijun; Sun, Zhirong; Liu, Wenlan; Chen, Long; DU, Yuan; Wei, Xinxin

    2014-01-01

    The aim of this study was to investigate the correlation between root respiration and the percentage of active components in licorice (Glycyrrhiza uralensis Fisch.), in order to provide a foundation for the regulation and modulation of the quality of G. uralensis. Respiration efflux of annual and biennial G. uralensis was determined using a Li-7000 CO2/H2O analyzer. The root systems were scanned at a resolution of 3,000 dpi using an Epson Expression 10000XL scanner. Root growth was determined by analyzing the scanned images using WinRHIZO version Pro2007d software and the rate of respiration in the root was subsequently calculated. In addition, the percentages of the five major active components in licorice, glycyrrhizic acid, glycyrrhizin, isoliquiritin, liquiritigenin and isoliquiritigenin, were detected using high-performance liquid chromatography (HPLC). The correlation between the root respiration and the percentage of the active components was investigated. Significant seasonal changes were observed in the rates of respiration of first and zero-class roots. In annual and biennial G. uralensis, the maximum and minimum values for rate of respiration were present in July (P<0.05) and November (P<0.05), respectively. The correlation coefficients between the five major active components and the rate of respiration were -0.304 (glycyrrhizin), -0.129 (liquiritigenin), -0.441 (glycyrrhizic acid; P<0.05), -0.471 (isoliquiritin; P<0.05) and 0.148 (isoliquiritigenin). The percentages of glycyrrhizic acid and isoliquiritin were significantly negatively correlated with the rate of respiration in annual and biennial G. uralensis. Understanding the correlation between the root rate of respiration and the active components in G. uralensis may be beneficial to ensuring the quality of cultivated G. uralensis.

  5. [Evaluation on contribution rate of each component total salvianolic acids and characterization of apparent oil/water partition coefficient].

    PubMed

    Yan, Hong-mei; Chen, Xiao-yun; Xia, Hai-jian; Liu, Dan; Jia, Xiao-bin; Zhang, Zhen-hai

    2015-02-01

    The difference between three representative components of total salvianolic acids in pharmacodynamic activity were compared by three different pharmacological experiments: HUVECs oxidative damage experiment, 4 items of blood coagulation in vitro experiment in rabbits and experimental myocardial ischemia in rats. And the effects of contribution rate of each component were calculated by multi index comprehensive evaluation method based on CRITIC weights. The contribution rates of salvianolic acid B, rosmarinic acid and Danshensu were 28.85%, 30.11%, 41.04%. Apparent oil/water partition coefficient of each representative components of total salvianolic acids in n-octyl alcohol-buffer was tested and the total salvianolic acid components were characterized based on a combination of the approach of self-defined weighting coefficient with effects of contribution rate. Apparent oil/water partition coefficient of total salvianolic acids was 0.32, 1.06, 0.89, 0.98, 0.90, 0.13, 0.02, 0.20, 0.56 when in octanol-water/pH 1.2 dilute hydrochloric acid solution/ pH 2.0, 2.5, 5.0, 5.8, 6.8, 7.4, 7.8 phosphate buffer solution. It provides a certain reference for the characterization of components.

  6. Relationship between physical activity and the very low-frequency component of heart rate variability after stroke.

    PubMed

    Usui, Harunobu; Nishida, Yuusuke

    2015-04-01

    The present study aimed to clarify the relationship between high physical activity (PA) and function of the autonomic nervous system, which is important in the prognosis after stroke. We hypothesized a positive association between PA and the very low-frequency (VLF) component of heart rate variability (HRV). Eight patients participated in this study. PA was measured using an accelerometer, and HRV was measured using a heart rate monitor. A significant and positive relationship was observed between the VLF component of HRV and PA. A significant negative relationship was observed between the VLF component of HRV and the duration of inactivity. No significant relationship was identified between the low-to-high frequency ratio of HRV and between the high-frequency component of HRV and PA. A positive correlation was observed between the VLF component of HRV and PA in stroke patients. Therefore, the VLF component of HRV links PA to cardiovascular prognosis. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  7. Reproducibility for Heart Rate Variability Analysis during 6-Min Walk Test in Patients with Heart Failure and Agreement between Devices.

    PubMed

    Braga, Lays Magalhães; Prado, Gustavo Faibischew; Umeda, Iracema Ioco Kikuchi; Kawauchi, Tatiana Satie; Taboada, Adriana Marques Fróes; Azevedo, Raymundo Soares; Pereira Filho, Horacio Gomes; Grupi, César José; Souza, Hayala Cristina Cavenague; Moreira, Dalmo Antônio Ribeiro; Nakagawa, Naomi Kondo

    2016-01-01

    Heart rate variability (HRV) analysis is a useful method to assess abnormal functioning in the autonomic nervous system and to predict cardiac events in patients with heart failure (HF). HRV measurements with heart rate monitors have been validated with an electrocardiograph in healthy subjects but not in patients with HF. We explored the reproducibility of HRV in two consecutive six-minute walk tests (6MW), 60-minute apart, using a heart rate monitor (PolarS810i) and a portable electrocardiograph (called Holter) in 50 HF patients (mean age 59 years, NYHA II, left ventricular ejection fraction ~35%). The reproducibility for each device was analysed using a paired t-test or the Wilcoxon signed-rank test. Additionally, we assessed the agreement between the two devices based on the HRV indices at rest, during the 6MW and during recovery using concordance correlation coefficients (CCC), 95% confidence intervals and Bland-Altman plots. The test-retest for the HRV analyses was reproducible using Holter and PolarS810i at rest but not during recovery. In the second 6MW, patients showed significant increases in rMSSD and walking distance. The PolarS810i measurements had remarkably high concordance correlation [0.86rates, a small effect in increasing differences between Holter and Polar in R-R intervals was observed. In conclusion, our study showed good reproducibility of HRV at rest in two consecutive 6MW using Holter and PolarS810i. Additionally, PolarS810i produced good agreements in short-term HRV indices based on Holter simultaneous recordings at rest, during the 6MW and recovery in HF patients.

  8. Reproducibility for Heart Rate Variability Analysis during 6-Min Walk Test in Patients with Heart Failure and Agreement between Devices

    PubMed Central

    Braga, Lays Magalhães; Prado, Gustavo Faibischew; Umeda, Iracema Ioco Kikuchi; Kawauchi, Tatiana Satie; Taboada, Adriana Marques Fróes; Azevedo, Raymundo Soares; Pereira Filho, Horacio Gomes; Grupi, César José; Souza, Hayala Cristina Cavenague; Moreira, Dalmo Antônio Ribeiro

    2016-01-01

    Heart rate variability (HRV) analysis is a useful method to assess abnormal functioning in the autonomic nervous system and to predict cardiac events in patients with heart failure (HF). HRV measurements with heart rate monitors have been validated with an electrocardiograph in healthy subjects but not in patients with HF. We explored the reproducibility of HRV in two consecutive six-minute walk tests (6MW), 60-minute apart, using a heart rate monitor (PolarS810i) and a portable electrocardiograph (called Holter) in 50 HF patients (mean age 59 years, NYHA II, left ventricular ejection fraction ~35%). The reproducibility for each device was analysed using a paired t-test or the Wilcoxon signed-rank test. Additionally, we assessed the agreement between the two devices based on the HRV indices at rest, during the 6MW and during recovery using concordance correlation coefficients (CCC), 95% confidence intervals and Bland-Altman plots. The test-retest for the HRV analyses was reproducible using Holter and PolarS810i at rest but not during recovery. In the second 6MW, patients showed significant increases in rMSSD and walking distance. The PolarS810i measurements had remarkably high concordance correlation [0.86rates, a small effect in increasing differences between Holter and Polar in R-R intervals was observed. In conclusion, our study showed good reproducibility of HRV at rest in two consecutive 6MW using Holter and PolarS810i. Additionally, PolarS810i produced good agreements in short-term HRV indices based on Holter simultaneous recordings at rest, during the 6MW and recovery in HF patients. PMID:27936043

  9. The effects of baseline heart rate recovery normality and exercise training protocol on heart rate recovery in patients with heart failure.

    PubMed

    Yaylalı, Yalın Tolga; Fındıkoğlu, Gülin; Yurtdaş, Mustafa; Konukçu, Sibel; Şenol, Hande

    2015-09-01

    It is unclear which exercise training protocol yields superior heart rate recovery (HRR) improvement in heart failure (HF) patients. Whether baseline HRR normality plays a role in the improvement is unknown. We hypothesized that an exercise training protocol and baseline HRR normality would be factors in altering HRR in HF patients. In this prospective, randomized, controlled and 3 group parallel study, 41 stable HF patients were randomly assigned to 3-times-weekly training sessions for 12 weeks, consisting of i) 30 minutes of interval training (IT) (n=17, 63.7±8.8 years old) versus ii) 30 minutes of continuous training (CT) (n=13, 59.6±6.8 years old) versus iii) no training (CON) (n=11, 60.6±9.9 years old). Each patient had cardiopulmonary exercise testing before and after the training program. Maximum heart rates attained during the test and heart rates at 1 and 2 min (HRR1 and HRR2) during the recovery phase were recorded. Paired samples t-test or Wilcoxon signed-rank test was used for comparisons before and after training. One-way ANOVA or Kruskal-Wallis variance analysis was used for comparisons among groups. HRR1 was unchanged after training. HRR2 improved in the IT group after training, and post-training HRR2 values were significantly faster in the IT group than in controls. Both HRR1 and HRR2 was significantly faster, irrespective of exercise protocol in patients with abnormal baseline values after training. HRR1 did not improve after training. HRR2 improved only in the IT group. Both HRRs in patients with abnormal baseline values improved after both exercise protocols. IT might be superior to CT in improving HRR2. Baseline HRR might play a role in its response to exercise.

  10. Rate-dependent force, intracellular calcium, and action potential voltage alternans are modulated by sarcomere length and heart failure induced-remodeling of thin filament regulation in human heart failure: A myocyte modeling study.

    PubMed

    Zile, Melanie A; Trayanova, Natalia A

    2016-01-01

    Microvolt T-wave alternans (MTWA) testing identifies heart failure patients at risk for lethal ventricular arrhythmias at near-resting heart rates (<110 beats per minute). Since pressure alternans occurs simultaneously with MTWA and has a higher signal to noise ratio, it may be a better predictor of arrhythmia, although the mechanism remains unknown. Therefore, we investigated the relationship between force alternans (FORCE-ALT), the cellular manifestation of pressure alternans, and action potential voltage alternans (APV-ALT), the cellular driver of MTWA. Our goal was to uncover the mechanisms linking APV-ALT and FORCE-ALT in failing human myocytes and to investigate how the link between those alternans was affected by pacing rate and by physiological conditions such as sarcomere length and heart failure induced-remodeling of mechanical parameters. To achieve this, a mechanically-based, strongly coupled human electromechanical myocyte model was constructed. Reducing the sarcoplasmic reticulum calcium uptake current (Iup) to 27% was incorporated to simulate abnormal calcium handling in human heart failure. Mechanical remodeling was incorporated to simulate altered thin filament activation and crossbridge (XB) cycling rates. A dynamical pacing protocol was used to investigate the development of intracellular calcium concentration ([Ca]i), voltage, and active force alternans at different pacing rates. FORCE-ALT only occurred in simulations incorporating reduced Iup, demonstrating that alternans in the intracellular calcium concentration (CA-ALT) induced FORCE-ALT. The magnitude of FORCE-ALT was found to be largest at clinically relevant pacing rates (<110 bpm), where APV-ALT was smallest. We found that the magnitudes of FORCE-ALT, CA-ALT and APV-ALT were altered by heart failure induced-remodeling of mechanical parameters and sarcomere length due to the presence of myofilament feedback. These findings provide important insight into the relationship between heart-failure

  11. Rate-dependent force, intracellular calcium, and action potential voltage alternans are modulated by sarcomere length and heart failure induced-remodeling of thin filament regulation in human heart failure: A myocyte modeling study

    PubMed Central

    Zile, Melanie A.

    2016-01-01

    Microvolt T-wave alternans (MTWA) testing identifies heart failure patients at risk for lethal ventricular arrhythmias at near-resting heart rates (<110 beats per minute). Since pressure alternans occurs simultaneously with MTWA and has a higher signal to noise ratio, it may be a better predictor of arrhythmia, although the mechanism remains unknown. Therefore, we investigated the relationship between force alternans (FORCE-ALT), the cellular manifestation of pressure alternans, and APV-ALT, the cellular driver of MTWA. Our goal was to uncover the mechanisms linking APV-ALT and FORCE-ALT in failing human myocytes and to investigate how the link between those alternans was affected by pacing rate and by physiological conditions such as sarcomere length and heart failure induced-remodeling of mechanical parameters. To achieve this, a mechanically-based, strongly coupled human electromechanical myocyte model was constructed. Reducing the sarcoplasmic reticulum calcium uptake current (Iup) to 27% was incorporated to simulate abnormal calcium handling in human heart failure. Mechanical remodeling was incorporated to simulate altered thin filament activation and crossbridge (XB) cycling rates. A dynamical pacing protocol was used to investigate the development of intracellular calcium concentration ([Ca]i), voltage, and active force alternans at different pacing rates. FORCE-ALT only occurred in simulations incorporating reduced Iup, demonstrating that alternans in the intracellular calcium concentration (CA-ALT) induced FORCE-ALT. The magnitude of FORCE-ALT was found to be largest at clinically relevant pacing rates (<110 bpm), where APV-ALT was smallest. We found that the magnitudes of FORCE-ALT, CA-ALT and APV-ALT were altered by heart failure induced-remodeling of mechanical parameters and sarcomere length due to the presence of myofilament feedback. These findings provide important insight into the relationship between heart-failure-induced electrical and mechanical

  12. Delivering heart failure disease management in 3 tertiary care centers: key clinical components and venues of care.

    PubMed

    Shah, Monica R; Whellan, David J; Peterson, Eric D; Nohria, Anju; Hasselblad, Vic; Xue, Zhenyi; Bowers, Margaret T; O'Connor, Christopher M; Califf, Robert M; Stevenson, Lynne W

    2008-04-01

    Little data exist to assist to help those organizing and managing heart failure (HF) disease management (DM) programs. We aimed to describe the intensity of outpatient HF care (clinic visits and telephone calls) and medical and nonpharmacological interventions in the outpatient setting. This was a prospective substudy of 130 patients enrolled in STARBRITE in HFDM programs at 3 centers. Follow-up occurred 10, 30, 60, 90, and 120 days after discharge. The number of clinic visits and calls made by HF cardiologists, nurse practitioners, and nurses were prospectively tracked. The results were reported as medians and interquartile ranges. There were a total of 581 calls with 4 (2, 6) per patient and 467 clinic visits with 3 (2, 5) per patient. Time spent per patient was 8.9 (6, 10.6) minutes per call and 23.8 (20, 28.3) minutes per clinic visit. Nurses and nurse practitioners spent 113 hours delivering care on the phone, and physicians and nurse practitioners spent 187.6 hours in clinic. Issues addressed during calls included HF education (341 times [52.6%]) and fluid overload (87 times [41.8%]). Medical interventions included adjustments to loop diuretics (calls 101 times, clinic 156 times); beta-blockers (calls 18 times, clinic 126 times); vasodilators (calls 8 times, clinic 55 times). More than a third of clinician time was spent on calls, during which >50% of patient contacts and HF education and >39% of diuretic adjustments occurred. Administrators and public and private insurers need to recognize the amount of medical care delivered over the telephone and should consider reimbursement for these activities.

  13. The effect of different cooling rates and coping thicknesses on the failure load of zirconia-ceramic crowns after fatigue loading

    PubMed Central

    Tang, Yu Lung; Kim, Jee-Hwan; Shim, June-Sung

    2017-01-01

    PURPOSE The purpose of this study was to evaluate the influence of different coping thicknesses and veneer ceramic cooling rates on the failure load of zirconia-ceramic crowns. MATERIALS AND METHODS Zirconia copings of two different thicknesses (0.5 mm or 1.5 mm; n=20 each) were fabricated from scanning 40 identical abutment models using a dental computer-aided design and computer-aided manufacturing system. Zirconia-ceramic crowns were completed by veneering feldspathic ceramics under different cooling rates (conventional or slow, n=20 each), resulting in 4 different groups (CONV05, SLOW05, CONV15, SLOW15; n=10 per group). Each crown was cemented on the abutment. 300,000 cycles of a 50-N load and thermocycling were applied on the crown, and then, a monotonic load was applied on each crown until failure. The mean failure loads were evaluated with two-way analysis of variance (P=.05). RESULTS No cohesive or adhesive failure was observed after fatigue loading with thermocycling. Among the 4 groups, SLOW15 group (slow cooling and 1.5 mm chipping thickness) resulted in a significantly greater mean failure load than the other groups (P<.001). Coping fractures were only observed in SLOW15 group. CONCLUSION The failure load of zirconia-ceramic crowns was significantly influenced by cooling rate as well as coping thickness. Under conventional cooling conditions, the mean failure load was not influenced by the coping thickness; however, under slow cooling conditions, the mean failure load was significantly influenced by the coping thickness. PMID:28680545

  14. A Novel and Effective Method for Congestive Heart Failure Detection and Quantification Using Dynamic Heart Rate Variability Measurement

    PubMed Central

    Chen, Wenhui; Zheng, Lianrong; Li, Kunyang; Wang, Qian; Liu, Guanzheng; Jiang, Qing

    2016-01-01

    Risk assessment of congestive heart failure (CHF) is essential for detection, especially helping patients make informed decisions about medications, devices, transplantation, and end-of-life care. The majority of studies have focused on disease detection between CHF patients and normal subjects using short-/long-term heart rate variability (HRV) measures but not much on quantification. We downloaded 116 nominal 24-hour RR interval records from the MIT/BIH database, including 72 normal people and 44 CHF patients. These records were analyzed under a 4-level risk assessment model: no risk (normal people, N), mild risk (patients with New York Heart Association (NYHA) class I-II, P1), moderate risk (patients with NYHA III, P2), and severe risk (patients with NYHA III-IV, P3). A novel multistage classification approach is proposed for risk assessment and rating CHF using the non-equilibrium decision-tree–based support vector machine classifier. We propose dynamic indices of HRV to capture the dynamics of 5-minute short term HRV measurements for quantifying autonomic activity changes of CHF. We extracted 54 classical measures and 126 dynamic indices and selected from these using backward elimination to detect and quantify CHF patients. Experimental results show that the multistage risk assessment model can realize CHF detection and quantification analysis with total accuracy of 96.61%. The multistage model provides a powerful predictor between predicted and actual ratings, and it could serve as a clinically meaningful outcome providing an early assessment and a prognostic marker for CHF patients. PMID:27835634

  15. A Novel and Effective Method for Congestive Heart Failure Detection and Quantification Using Dynamic Heart Rate Variability Measurement.

    PubMed

    Chen, Wenhui; Zheng, Lianrong; Li, Kunyang; Wang, Qian; Liu, Guanzheng; Jiang, Qing

    2016-01-01

    Risk assessment of congestive heart failure (CHF) is essential for detection, especially helping patients make informed decisions about medications, devices, transplantation, and end-of-life care. The majority of studies have focused on disease detection between CHF patients and normal subjects using short-/long-term heart rate variability (HRV) measures but not much on quantification. We downloaded 116 nominal 24-hour RR interval records from the MIT/BIH database, including 72 normal people and 44 CHF patients. These records were analyzed under a 4-level risk assessment model: no risk (normal people, N), mild risk (patients with New York Heart Association (NYHA) class I-II, P1), moderate risk (patients with NYHA III, P2), and severe risk (patients with NYHA III-IV, P3). A novel multistage classification approach is proposed for risk assessment and rating CHF using the non-equilibrium decision-tree-based support vector machine classifier. We propose dynamic indices of HRV to capture the dynamics of 5-minute short term HRV measurements for quantifying autonomic activity changes of CHF. We extracted 54 classical measures and 126 dynamic indices and selected from these using backward elimination to detect and quantify CHF patients. Experimental results show that the multistage risk assessment model can realize CHF detection and quantification analysis with total accuracy of 96.61%. The multistage model provides a powerful predictor between predicted and actual ratings, and it could serve as a clinically meaningful outcome providing an early assessment and a prognostic marker for CHF patients.

  16. [Impact of telemetric management on overall treatment costs and mortality rate among patients with chronic heart failure].

    PubMed

    Kielblock, B; Frye, Ch; Kottmair, S; Hudler, Th; Siegmund-Schultze, E; Middeke, M

    2007-03-02

    The rising prevalence of chronic heart failure (CHF) has led to an increase in total treatment expenditures. A medical care programme of telemetry was developed to reduce the number of patients with decompensated CHF, hospital admissions and overall treatment cost. As part of a prospective controlled study the body weight of 251 patients with CHF was monitored over one year. The supervising center contacted the patients whenever their body weight exceeded a threshold value. Patients were phoned by a designated personal adviser and received regular informative material and advice by specialist medical personnel. Patients' general practitioners had been involved in recruiting patients and by regularly sending them follow-up reports. Another group of 251 patients who had not received the described telemetric intervention served as control. The mean age of the patients was 71.7 years, lower than the 76.4 years of the control group. More patients in the intervention groups were in NYHA class III and IV than in the control group (52 % vs 36 %). After an average observation period of 12 months the duration of hospital stay had been reduced by 48 % (p = 0.01), the hospital costs by EUR 7128 per patient p = 0.01), while drug expenditure had increased by EUR 245 per patient (not significant). The total costs had thus fallen by EUR 6993 per patient (-39.5 %; p = 0.05). The mortality rate of 14.7 % in the intervention group was significantly lower than that of the control group of 27.1 % (p = 0.001). The reduction in costs and mortality rate was clearly greater for men than women. Total expenditure had been highest for patients who had died. The results indicate that total treatment costs and mortality rate can be reduced by telemetric monitoring of patients in CHF, especially in men.

  17. The reversal of the rotational modulation rates of the north and south components of Saturn kilometric radiation near equinox

    NASA Astrophysics Data System (ADS)

    Gurnett, D. A.; Groene, J. B.; Persoon, A. M.; Menietti, J. D.; Ye, S.-Y.; Kurth, W. S.; MacDowall, R. J.; Lecacheux, A.

    2010-12-01

    It has been known for many years that Saturn emits intense radio emissions at kilometer wavelengths and that this radiation is modulated by the rotation of the planet at a rate that varies slowly on time scales of years. Recently it has been shown that the radio emission consists of two components that have different rotational modulation rates, one emitted from the northern auroral region and the other emitted from the southern auroral region. In this paper we show using radio measurements from the Cassini spacecraft that the rotational modulation rates of the northern and southern components reversed near Saturn's recent equinox, which occurred on 11 August 2009. We show that a similar reversal was also observed by the Ulysses spacecraft near the previous equinox, which occurred on 19 November 1995. The solar control implied by these reversals has important implications on how Saturn's rotation is coupled into the magnetosphere.

  18. Leuco-crystal-violet micelle gel dosimeters: Component effects on dose-rate dependence

    NASA Astrophysics Data System (ADS)

    Xie, J. C.; Katz, E. A. B.; Alexander, K. M.; Schreiner, L. J.; McAuley, K. B.

    2017-05-01

    Designed experiments were performed to produce empirical models for the dose sensitivity, initial absorbance, and dose-rate dependence respectively for leucocrystal violet (LCV) micelle gel dosimeters containing cetyltrimethylammonium bromide (CTAB) and 2,2,2-trichloroethanol (TCE). Previous gels of this type showed dose-rate dependent behaviour, producing an ∼18% increase in dose sensitivity between dose rates of 100 and 600 cGy min-1. Our models predict that the dose rate dependence can be reduced by increasing the concentration of TCE, CTAB and LCV. Increasing concentrations of LCV and CTAB produces a significant increase in dose sensitivity with a corresponding increase in initial absorbance. An optimization procedure was used to determine a nearly dose-rate independent gel which maintained high sensitivity and low initial absorbance. This gel which contains 33 mM CTAB, 1.25 mM LCV, and 96 mM TCE in 25 mM trichloroacetic acid and 4 wt% gelatin showed an increase in dose sensitivity of only 4% between dose rates of 100 and 600 cGy min-1, and provides an 80% greater dose sensitivity compared to Jordan’s standard gels with similar initial absorbance.

  19. [Cardiopulmonary exercise test and heart rate variability in patients with congestive heart failure who underwent physical rehabilitation].

    PubMed

    Kubinyi, Aleksandra; Bacior, Bogumiła; Szot, Wojclech; Klecha, Artur; Kawecka-Jaszcz, Kalina

    2003-01-01

    Physical rehabilitation of patients with heart diseases is a well-known therapeutical method used in patients with heart failure. However there is no consensus regarding rehabilitation program for these patients. The aim of this study was to assess tolerance of physical exercise and parameters of heart rate variability in patients with chronic heart failure who were exercised using different models of training. 42 patients (mean age 55.9 +/- 8.2) with chronic heart failure (NYHA class II and III) were included into this study. They were divided randomly into three groups, each number 14 patients: group A--patients who were trained according to model with progressive increase of workload, group B--patients with interval training, and group C--patients who were not trained at all. The study groups did not differ in average age, BMI, NYHA class, or pharmacological treatment. All patients from groups A and B were rehabilitated during six months, 3 times per week for 1.0 hour each time. All patients were submitted to the following examinations before and after six months of training: echocardiography, cardiopulmonary exercise test and 24-hour ECG recording with evaluation of time-domain HRV parameters. In groups A and B we observed an improvement in exercise capacity, which was more pronounced in group A. This improvement was observed as increase in total exercise time when compared with group B and C (839.1 +/- 98.3 sec vs 472.4 +/- 39.7 sec vs 347.92 +/- 61.0 sec respectively at p < 0.0001), and increase in workload (6.28 +/- 0.8 MET vs 3.9 +/- 0.2 MET vs 2.6 +/- 0.63 MET respectively in the study groups). We also found improved cardiopulmonary exercise test. After six months we observed significant differences in all parameters between group A and C, and in VO2max between group B and C (16.5 +/- 1.9 vs 14.1 +/- 1.9 ml/kg/min, p < 0.01) and in VE/VCO2 (37.8 +/- 4.2 vs 40.4 +/- 6.7 l/min, p < 0.01). After 6 months we also found significant differences between group A

  20. Algorithms and components for all-optical high-bit-rate digital processors-multipliers

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Lopez, Arturo Aguirre

    2005-08-01

    We present both the estimation of main parameters and the previously obtained experimental data related to some algorithms and components for all-optical digital processors- multipliers. An all-optical multiplication in a mixed binary format may be designed with an array of non-collinear second-harmonic generation based optical AND-gates arranged in a square-law optically nonlinear medium. The modern approach, based on the concept of arranging light beams in space and time using the regime of spatiotemporall solitons or light bullets, is generally discussed.

  1. Payload and Components Real-Time Automated Test System (PACRATS), Data Acquisition of Leak Rate and Pressure Data Test Procedure

    NASA Technical Reports Server (NTRS)

    Rinehart, Maegan L.

    2011-01-01

    The purpose of this activity is to provide the Mechanical Components Test Facility (MCTF) with the capability to obtain electronic leak test and proof pressure data, Payload and Components Real-time Automated Test System (PACRATS) data acquisition software will be utilized to display real-time data. It will record leak rates and pressure/vacuum level(s) simultaneously. This added functionality will provide electronic leak test and pressure data at specified sampling frequencies. Electronically stored data will provide ES61 with increased data security, analysis, and accuracy. The tasks performed in this procedure are to verify PACRATS only, and are not intended to provide verifications for MCTF equipment.

  2. Cross sectional longitudinal study of spot morning urine protein:creatinine ratio, 24 hour urine protein excretion rate, glomerular filtration rate, and end stage renal failure in chronic renal disease in patients without diabetes.

    PubMed Central

    Ruggenenti, P.; Gaspari, F.; Perna, A.; Remuzzi, G.

    1998-01-01

    OBJECTIVE: To evaluate whether the protein:creatinine ratio in spot morning urine samples is a reliable indicator of 24 hour urinary protein excretion and predicts the rate of decline of glomerular filtration rate and progression to end stage renal failure in non-diabetic patients with chronic nephropathy. DESIGN: Cross sectional correlation between the ratio and urinary protein excretion rate. Univariate and multivariate analysis of baseline predictors, including the ratio and 24 hour urinary protein, of decline in glomerular filtration rate and end stage renal failure in the long term. SETTING: Research centre in Italy. SUBJECTS: 177 non-diabetic outpatients with chronic renal disease screened for participation in the ramipril efficacy in nephropathy study. MAIN OUTCOME MEASURES: Rate of decline in filtration rate evaluated by repeated measurements of unlabelled iohexol plasma clearance and rate of progression to renal failure. RESULTS: Protein:creatinine ratio was significantly correlated with absolute and log transformed 24 hour urinary protein values (P = 0.0001 and P < 0.0001, respectively.) Ratios also had high predictive value for rate of decline of the glomerular filtration rate (univariate P = 0.0003, multivariate P = 0.004) and end stage renal failure (P = 0.002 and P = 0.04). Baseline protein:creatinine ratios and rate of decline of the glomerular filtration rate were also significantly correlated (P < 0.0005). In the lowest third of the protein:creatinine ratio (< 1.7) there was 3% renal failure compared with 21.2% in the highest third (> 2.7) (P < 0.05). CONCLUSIONS: Protein:creatinine ratio in spot morning urine samples is a precise indicator of proteinuria and a reliable predictor of progression of disease in non-diabetic patients with chronic nephropathies and represents a simple and inexpensive procedure in establishing severity of renal disease and prognosis. PMID:9501711

  3. Comparison of Clinical Failure Rates After 2 Techniques of Subpectoral Mini-Open Biceps Tenodesis: Sequence and Suture Passage Technique Matter

    PubMed Central

    Schrock, John B.; Kraeutler, Matthew J.; Bravman, Jonathan T.

    2017-01-01

    Background: A number of techniques are available for performing biceps tenodesis, the majority of which result in good or excellent outcomes. However, failure may result in pain and/or dissatisfying biceps deformity. Purpose: To compare the clinical failure rates of 2 methods of suture passage in subpectoral biceps tenodesis with suture anchors performed by the senior author. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective chart review was conducted of patients who underwent biceps tenodesis under the care of the senior author. Operative notes were used to determine whether the procedure was performed with a BirdBeak (BB) suture passer or a free needle (FN). Each subsequent clinical follow-up note was used to determine participation in physical therapy and duration, follow-up duration, and whether clinical tenodesis failure had occurred. Biceps tenodesis failure was defined as either cosmetic deformity (“Popeye” sign), pain at the tenodesis site, or need for revision. Results: Overall, 163 patients met the inclusion criteria (BB, n = 112; FN, n = 51). Mean follow-up was 5.3 months and 4.1 months in the BB and FN groups, respectively. Significantly more tenodesis failures occurred in the BB group (BB, 12%; FN, 2%, P = .042). Among all BB patients, 10% experienced failure due to cosmetic deformity, 2% required revision, and 4% had postoperative pain at the tenodesis site by latest follow-up. The 1 patient in the FN group who experienced failure presented with cosmetic deformity postoperatively. Conclusion: Biceps tenodesis with the use of an FN to pass the suture resulted in a significantly lower clinical failure rate compared with the use of a BB suture passer.

  4. Generalized discriminant analysis for congestive heart failure risk assessment based on long-term heart rate variability.

    PubMed

    Shahbazi, Fatemeh; Asl, Babak Mohammadzadeh

    2015-11-01

    The aims of this study are summarized in the following items: first, to investigate the class discrimination power of long-term heart rate variability (HRV) features for risk assessment in patients suffering from congestive heart failure (CHF); second, to introduce the most discriminative features of HRV to discriminate low risk patients (LRPs) and high risk patients (HRPs), and third, to examine the influence of feature dimension reduction in order to achieve desired accuracy of the classification. We analyzed two public Holter databases: 12 data of patients suffering from mild CHF (NYHA class I and II), labeled as LRPs and 32 data of patients suffering from severe CHF (NYHA class III and IV), labeled as HRPs. A K-nearest neighbor classifier was used to evaluate the performance of feature set in the classification. Moreover, to reduce the number of features as well as the overlap of the samples of two classes in feature space, we used generalized discriminant analysis (GDA) as a feature extraction method. By applying GDA to the discriminative nonlinear features, we achieved sensitivity and specificity of 100% having the least number of features. Finally, the results were compared with other similar conducted studies regarding the performance of feature selection procedure and classifier besides the number of features used in training.

  5. Automated versus interactive spectral analysis of heart rate variability from 24-hour Holter recordings in heart failure patients.

    PubMed

    Maestri, Roberto; La Rovere, Maria Teresa; Pinna, Gian Domenico

    2012-01-01

    Accurate spectral analysis of 24-hour heart rate variability (HRV) requires time consuming interactive control of the overall processing, limiting its feasibility in large scale clinical trials. Fully automatic procedures allow a dramatic reduction of analysis time but the level of accuracy loss is unknown. In this study we compared automatic and interactive measurements of HRV indexes in a sample of 246 Holter recordings from chronic heart failure patients. We measured the total power of HRV and the power in the very low (0.01-0.04 Hz), low (0.04-0.15 Hz) and high (0.15-0.4 Hz) frequency bands. The comparison between the two methods was performed by computing the normalized difference between automatic and interactive measurements and estimating the bias and 95% limits of agreement. Automatic measurements showed a small bias (< ±8%) compared to interactive measurements, while the limits of agreement were ≤±23% in all spectral indexes. Our results indicate that the systematic and random difference between automatic and interactive measurements of spectral indexes of HRV are acceptable for clinical studies.

  6. Adherence to optimal heart rate control in heart failure with reduced ejection fraction: insight from a survey of heart rate in heart failure in Sweden (HR-HF study).

    PubMed

    Fu, M; Ahrenmark, U; Berglund, S; Lindholm, C J; Lehto, A; Broberg, A Månsson; Tasevska-Dinevska, G; Wikstrom, G; Ågard, A; Andersson, B

    2017-08-09

    Despite that heart rate (HR) control is one of the guideline-recommended treatment goals for heart failure (HF) patients, implementation has been painstakingly slow. Therefore, it would be important to identify patients who have not yet achieved their target heart rates and assess possible underlying reasons as to why the target rates are not met. The survey of HR in patients with HF in Sweden (HR-HF survey) is an investigator-initiated, prospective, multicenter, observational longitudinal study designed to investigate the state of the art in the control of HR in HF and to explore potential underlying mechanisms for suboptimal HR control with focus on awareness of and adherence to guidelines for HR control among physicians who focus on the contributing role of beta-blockers (BBs). In 734 HF patients the mean HR was 68 ± 12 beats per minute (bpm) (37.2% of the patients had a HR >70 bpm). Patients with HF with reduced ejection fraction (HFrEF) (n = 425) had the highest HR (70 ± 13 bpm, with 42% >70 bpm), followed by HF with preserved ejection fraction and HF with mid-range ejection fraction. Atrial fibrillation, irrespective of HF type, had higher HR than sinus rhythm. A similar pattern was observed with BB treatment. Moreover, non-achievement of the recommended target HR (<70 bpm) in HFrEF and sinus rhythm was unrelated to age, sex, cardiovascular risk factors, cardiovascular diseases, and comorbidities, but was related to EF and the clinical decision of the physician. Approximately 50% of the physicians considered a HR of >70 bpm optimal and an equal number considered a HR of >70 bpm too high, but without recommending further action. Furthermore, suboptimal HR control cannot be attributed to the use of BBs because there was neither a difference in use of BBs nor an interaction with BBs for HR >70 bpm compared with HR <70 bpm. Suboptimal control of HR was noted in HFrEF with sinus rhythm, which appeared to be attributable to physician decision

  7. Cardiac Mitochondrial Proteome Dynamics with Heavy Water Reveals Stable Rate of Mitochondrial Protein Synthesis in Heart Failure Despite Decline in Mitochondrial Oxidative Capacity

    PubMed Central

    Shekar, Kadambari Chandra; Li, Ling; Dabkowski, Erinne R.; Xu, Wenhong; Ribeiro, Rogerio Faustino; Hecker, Peter A.; Recchia, Fabio A.; Sadygov, Rovshan G.; Willard, Belinda; Kasumov, Takhar; Stanley, William C.

    2017-01-01

    We recently developed a method to measure mitochondrial proteome dynamics with heavy water (2H2O)-based metabolic labeling and high resolution mass spectrometry. We reported the half-lives and synthesis rates of several proteins in the two cardiac mitochondrial subpopulations, subsarcolemmal and interfibrillar (SSM and IFM), in Sprague Dawley rats. In the present study, we tested the hypothesis that the mitochondrial protein synthesis rate is reduced in heart failure, with possible differential changes in SSM versus IFM. Six to seven week old male Sprague Dawley rats underwent transverse aortic constriction (TAC) and developed moderate heart failure after 22 weeks. Heart failure and sham rats of the same age received heavy water (5% in drinking water) for up to 80 days. Cardiac SSM and IFM were isolated from both groups and the proteins were separated by 1D gel electrophoresis. Heart failure reduced protein content and increased the turnover rate of several proteins involved in fatty acid oxidation, electron transport chain and ATP synthesis, while it decreased the turnover of other proteins, including pyruvate dehydrogenase subunit in IFM, but not in SSM. Because of these bidirectional changes, the average overall half-life of proteins was not altered by heart failure in both SSM and IFM. The kinetic measurements of individual mitochondrial proteins presented in this study may contribute to a better understanding of the mechanisms responsible for mitochondrial alterations in the failing heart. PMID:24995939

  8. Incidence and clinical relevance of uncontrolled ventricular rate during atrial fibrillation in heart failure patients treated with cardiac resynchronization therapy.

    PubMed

    Boriani, Giuseppe; Gasparini, Maurizio; Landolina, Maurizio; Lunati, Maurizio; Proclemer, Alessandro; Lonardi, Gabriele; Iacopino, Saverio; Rahue, Werner; Biffi, Mauro; DiStefano, Paola; Grammatico, Andrea; Santini, Massimo

    2011-08-01

    Uncontrolled ventricular rate (VR) during atrial fibrillation (AF) may cause clinical deterioration in heart failure (HF) patients who need continuous biventricular pacing to achieve cardiac resynchronization therapy (CRT). We aimed at evaluating the association between AF, uncontrolled VR, and sub-optimal CRT, defined as low biventricular pacing percentage (BIVP%). All 1404 patients had HF, New York Heart Association (NYHA) ≥II, left ventricular ejection fraction (LVEF) ≤35%, and QRS ≥120 ms, and received an implantable CRT defibrillator (CRT-D). Occurrence of AF, VR during AF and lifetime BIVP% were estimated from device data. Ventricular rate during AF was defined as uncontrolled in patients with mean VR>80 bpm and maximum VR>110 bpm. Over a median follow-up of 18 months, AF was detected in 443 of 1404 patients (32%). In this sub-group of AF patients, VR during AF was uncontrolled in 150 of 443 patients (34%). Multivariate Cox regression analysis showed that age [hazard ratio (HR) = 1.03, 95% confidence interval (CI) = 1.00-1.06, P= 0.028], and uncontrolled VR [HR = 1.69 (CI = 1.01-2.83), P= 0.046] were the only independent predictors of clinical outcome, assessed by HF hospitalizations and death. The median lifetime BIVP% was 95% (25-75 percentile range 91-99%). Biventricular pacing percentage was significantly and inversely correlated to VR, decreasing by 7% for each 10 bpm increase in VR. Sub-optimal CRT, defined as BIVP% <95%, was predicted by the occurrence of persistent or permanent AF [odds ratio (OR) = 3.77, CI = 2.44-5.82, P< 0.001], and uncontrolled VR [OR = 2.25, CI = 1.35-3.73, P= 0.002]. Uncontrolled VR occurs in one-third of CRT-D patients, who experience AF, and is associated with HF hospitalizations and death and with sub-optimal CRT (lifetime BIVP%<95%).

  9. Central exogenous nitric oxide decreases cardiac sympathetic drive and improves baroreflex control of heart rate in ovine heart failure.

    PubMed

    Ramchandra, Rohit; Hood, Sally G; May, Clive N

    2014-08-01

    Heart failure (HF) is associated with increased cardiac and renal sympathetic drive, which are both independent predictors of poor prognosis. A candidate mechanism for the centrally mediated sympathoexcitation in HF is reduced synthesis of the inhibitory neuromodulator nitric oxide (NO), resulting from downregulation of neuronal NO synthase (nNOS). Therefore, we investigated the effects of increasing the levels of NO in the brain, or selectively in the paraventricular nucleus of the hypothalamus (PVN), on cardiac sympathetic nerve activity (CSNA) and baroreflex control of CSNA and heart rate in ovine pacing-induced HF. The resting level of CSNA was significantly higher in the HF than in the normal group, but the resting level of RSNA was unchanged. Intracerebroventricular infusion of the NO donor sodium nitroprusside (SNP; 500 μg · ml(-1)· h(-1)) in conscious normal sheep and sheep in HF inhibited CSNA and restored baroreflex control of heart rate, but there was no change in RSNA. Microinjection of SNP into the PVN did not cause a similar cardiac sympathoinhibition in either group, although the number of nNOS-positive cells was decreased in the PVN of sheep in HF. Reduction of endogenous NO with intracerebroventricular infusion of N(ω)-nitro-l-arginine methyl ester decreased CSNA in normal but not in HF sheep and caused no change in RSNA in either group. These findings indicate that endogenous NO in the brain provides tonic excitatory drive to increase resting CSNA in the normal state, but not in HF. In contrast, exogenously administered NO inhibited CSNA in both the normal and HF groups via an action on sites other than the PVN. Copyright © 2014 the American Physiological Society.

  10. Metabolic Rates of ATP Transfer Through Creatine Kinase (CK Flux) Predict Clinical Heart Failure Events and Death

    PubMed Central

    Bottomley, Paul A.; Panjrath, Gurusher S.; Lai, Shenghan; Hirsch, Glenn A.; Wu, Katherine; Najjar, Samer S.; Steinberg, Angela; Gerstenblith, Gary; Weiss, Robert G.

    2015-01-01

    Morbidity and mortality from heart failure (HF) are high, and current risk stratification approaches for predicting HF progression are imperfect. Adenosine triphosphate (ATP) is required for normal cardiac contraction, and abnormalities in creatine kinase (CK) energy metabolism, the primary myocardial energy reserve reaction, have been observed in experimental and clinical HF. However, the prognostic value of abnormalities in ATP production rates through CK in human HF has not been investigated. Fifty-eight HF patients with nonischemic cardiomyopathy underwent 31P magnetic resonance spectroscopy (MRS) to quantify cardiac high-energy phosphates and the rate of ATP synthesis through CK (CK flux) and were prospectively followed for a median of 4.7 years. Multiple-event analysis (MEA) was performed for HF-related events including all-cause and cardiac death, HF hospitalization, cardiac transplantation, and ventricular-assist device placement. Among baseline demographic, clinical, and metabolic parameters, MEA identified four independent predictors of HF events: New York Heart Association (NYHA) class, left ventricular ejection fraction (LVEF), African-American race, and CK flux. Reduced myocardial CK flux was a significant predictor of HF outcomes, even after correction for NYHA class, LVEF, and race. For each increase in CK flux of 1 μmol g−1 s−1, risk of HF-related composite outcomes decreased by 32 to 39%. These findings suggest that reduced CK flux may be a potential HF treatment target. Newer imaging strategies, including noninvasive 31P MRS that detect altered ATP kinetics, could thus complement risk stratification in HF and add value in conditions involving other tissues with high energy demands, including skeletal muscle and brain. PMID:24337482

  11. Heart rate recovery after exercise in chronic heart failure: role of vital exhaustion and type D personality.

    PubMed

    von Känel, Roland; Barth, Jürgen; Kohls, Sonja; Saner, Hugo; Znoj, Hansjörg; Saner, Gaby; Schmid, Jean-Paul

    2009-04-01

    Vital exhaustion and type D personality previously predicted mortality and cardiac events in patients with chronic heart failure (CHF). Reduced heart rate recovery (HRR) also predicts morbidity and mortality in CHF. We hypothesized that elevated levels of vital exhaustion and type D personality are both associated with decreased HRR. Fifty-one patients with CHF (mean age 58+/-12 years, 82% men) and left ventricular ejection fraction (LVEF) < or = 40% underwent standard exercise testing before receiving outpatient cardiac rehabilitation. They completed the 9-item short form of the Maastricht Vital Exhaustion Questionnaire and the 14-item type D questionnaire asking about negative affectivity and social inhibition. HRR was calculated as the difference between heart rate at the end of exercise and 1 min after abrupt cessation of exercise (HRR-1). Regression analyses were adjusted for gender, age, LVEF, and maximum exercise capacity. Vital exhaustion explained 8.4% of the variance in continuous HRR-1 (p=0.045). For each point increase on the vital exhaustion score (range 0-18) there was a mean+/-SEM decrease of 0.54+/-0.26 bpm in HRR-1. Type D personality showed a trend toward statistical significance for being associated with lower levels of HRR-1 explaining 6.5% of the variance (p<0.08). The likelihood of having HRR-1 < or = 18 bpm was significantly higher in patients with type D personality than in those without (odds ratio=7.62, 95% CI 1.50-38.80). Elevated levels of vital exhaustion and type D personality were both independently associated with reduced HRR-1. The findings provide a hitherto not explored psychobiological explanation for poor cardiac outcome in patients with CHF.

  12. Limits to the rate of component separation in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Fomalont, E. B.; Geldzahler, B. J.; Hjellming, R. M.; Wade, C. M.

    1983-12-01

    On the basis of a variety of observational results, it is judged that Sco X-1 is a radio triple source with a morphology similar to that of luminous extragalactic sources. The beam model of continuous bulk kinetic flow from the radio core to the radio lobes will work in Sco X-1 only if (1) the beam flow is relativistic, (2) the conversion of bulk kinetic energy to radiative energy is of an efficiency greater than 10 percent, and (3) if the beam is stopped by a medium with a density of about 10/cu cm, which is about a factor of 30 higher than that of the typical interstellar medium. Other alternatives seem even less attractive than these. The size of the northeast component is smaller than that expected from diffusion of the electrons over their radiative age of about 200 years, based on an equipartition magnetic field strength of 0.005 gauss.

  13. Hydrolysis rates, methane production and nitrogen solubilisation of grey waste components during anaerobic degradation.

    PubMed

    Jokela, J P Y; Vavilin, V A; Rintala, J A

    2005-03-01

    Municipal grey waste (i.e. the remaining fraction in municipal waste management systems in which putrescibles (biowaste) and other recyclables (paper, metals, glass) are source-segregated) was manually sorted into six main fractions on the basis of composition and also separated by sieving (100 mm mesh size) into two fractions, oversized and undersized, respectively. In practice, in waste management plant the oversized fraction is (or will be) used to produce refuse-derived fuel and the undersized landfilled after biological stabilisation. The methane yields and nitrogen solubilisation of the grey waste and the different fractions (all studied samples were first milled to 5 mm particle samples) were determined in a 237-day methane production batch assay and in a water elution test, respectively. The grey waste was found to contained remnants of putrescibles and also a high amount of other biodegradable waste, including packaging, cartons and cardboard, newsprint, textiles and diapers. These waste fractions comprised 41%-w/w of the grey waste and produced 40-210 m3 methane (total solids (TS))(-1) and less than 0.01 g NH4-N kg TS(added)(-1) except diapers which produced 9.8 g NH4-N kg TS(added)(-1) in the batch assays. In the case of the two sieved fractions and on mass bases, most of the methane originated from the oversized fraction, whereas most of the NH4-N was solublised from the undersized fraction. The first-order kinetic model described rather well the degradation of each grey waste fraction and component, showing the different components to be in the range 0.021-0.058 d(-1), which was around one-sixth of the values reported for the source-segregated putrescible fraction of MSW.

  14. Evaluation of Risk Minimisation Measures for Blood Components - Based on Reporting Rates of Transfusion-Transmitted Reactions (1997-2013).

    PubMed

    Funk, Markus B; Heiden, Margarethe; Volkers, Peter; Lohmann, Annette; Keller-Stanislawski, Brigitte

    2015-07-01

    To assess the impact of safety measures, we compared reporting rates of transfusion-related reactions before and after the implementation of six measures in 1999, 2004, 2006, 2008 and 2009. Reporting rates of transfusion-transmitted bacterial infection (TTBI), viral infection (TTVI) and immune-mediated transfusion-related acute lung injury (TRALI) were calculated on the basis of confirmed annual reports and distributed blood components. The introduction of HCV NAT testing caused a significant reduction of HCV reporting rate from 1:0.6 to 1:83.16 million administered blood components (p < 0.0001), donor screening for antibodies to hepatitis B core antigen caused a reduction of HBV reporting rate from 1:2.90 to 1:10.70 million units (p = 0.0168). A significant reduction from 1:0.094 to 1:2.42 million fresh frozen plasma (FFP) units could also be achieved by risk minimisation TRALI measures (p < 0.0001). Implementation of pre-donation sampling did not result in a significant decrease in TTBI, whereas limitation of shelf life for platelet concentrate (PC) minimised the TTBI reporting rate from 1:0.088 to 1:0.19 million PC units (p = 0.041). For HIV NAT pool testing, no significant reduction in HIV transmission was found due to very low reporting rates (1:10 million versus 1:27 million blood components, p = 0.422). On the basis of haemovigilance data, a significant benefit could be demonstrated for four of six implemented safety measures.

  15. Rate of change in physical fitness and quality of life and depression following exercise training in patients with congestive heart failure.

    PubMed

    Smart, Neil A; Murison, Robert

    2013-01-01

    Exercise training appears to improve peak oxygen consumption (VO(2) ) and quality of life (QOL) in heart failure patients, although disease etiology, patient demographics and medication may alter the rate of adaptation. The authors sought to identify rate of change from baseline in fitness, QOL, and depression following exercise training in a cohort of patients with congestive heart failure. Thirty male systolic heart failure patients (aged 63.8±8.3 years, baseline peak VO(2) 12.2±4.8 mL/kg/min, left ventricular ejection fraction 28.2±9.4%, New York Heart Association class II/II 22/8) undertook 52 weeks of exercise training, 16 weeks as an outpatient and a further 36 weeks of home exercise. Peak VO(2) and QOL was measured using the Minnesota Living With Heart Failure (MLWHF) questionnaire and depression using the Hare-Davis scale. The authors analyzed the rate of change in peak VO(2) and MLWHF after grouping patients according to clinical, demographic, and pharmacologic characteristics. Peak VO(2) measurements varied over time, with no effect of disease pathology or β-blocker on peak VO(2) . The rate of change in physical MLWHF score was significantly greater (improved) during 0 to 16 weeks in patients with dilated pathology, but was not significantly affected by β-blocker use or age. The exercise training venue and supervision, or lack thereof, is the major determinant of adaptation to the intervention in heart failure patients, although age, β-adrenergic medication, and heart failure etiology also explain some of the variation in adaptive responses observed.

  16. Time-variant parametric estimation of transient quadratic phase couplings between heart rate components in healthy neonates.

    PubMed

    Schwab, K; Eiselt, M; Putsche, P; Helbig, M; Witte, H

    2006-12-01

    The heart rate variability (HRV) can be taken as an indicator of the coordination of the cardio-respiratory rhythms. Bispectral analysis using a direct (fast Fourier transform based) and time-invariant approach has shown the occurrence of a quadratic phase coupling (QPC) between a low-frequency (LF: 0.1 Hz) and a high-frequency (HF: 0.4-0.6 Hz) component of the HRV during quiet sleep in healthy neonates. The low-frequency component corresponds to the Mayer-Traube-Hering waves in blood pressure and the high-frequency component to the respiratory sinus arrhythmia (RSA). Time-variant, parametric estimation of the bispectrum provides the possibility of quantifying QPC in the time course. Therefore, the aim of this work was a parametric, time-variant bispectral analysis of the neonatal HRV in the same neonates used in the direct, time-invariant approach. For the first time rhythms in the time course of QPC between the HF component and the LF component could be shown in the neonatal HRV.

  17. Effects of Orthostatism and Hemodialysis on Mean Heart Period and Fractal Heart Rate Properties of Chronic Renal Failure Patients.

    PubMed

    Echeverría, Juan C; Infante, Oscar; Pérez-Grovas, Héctor; González, Hortensia; José, Marco V; Lerma, Claudia

    2017-05-26

    The aim of this work was to evaluate the short-term fractal index (α1 ) of heart rate variability (HRV) in chronic renal failure (CRF) patients by identifying the effects of orthostatism and hemodialysis (HD), and by evaluating the correlation between α1 and the mean RR interval from sinus beats (meanNN). HRV time series were derived from ECG data of 19 CRF patients and 20 age-matched healthy subjects obtained at supine and orthostatic positions (lasting 5 min each). Data from CRF patients were collected before and after HD. α1 was calculated from each time series and compared by analysis of variance. Pearson's correlations between meanNN and α1 were calculated using the data from both positions by considering three groups: healthy subjects, CRF before HD and CRF after HD. At supine position, α1 of CRF patients after HD (1.17 ± 0.30) was larger (P < 0.05) than in healthy subjects (0.89 ± 0.28) but not before HD (1.10 ± 0.34). α1 increased (P < 0.05) in response to orthostatism in healthy subjects (1.29 ± 0.26) and CRF patients after HD (1.34 ± 0.31), but not before HD (1.25 ± 0.37). Whereas α1 was correlated (P < 0.05) with the meanNN of healthy subjects (r = -0.562) and CRF patients after HD (r = -0.388), no significance in CRF patients before HD was identified (r = 0.003). Multiple regression analysis confirmed that α1 was mainly predicted by the orthostatic position (in all groups) and meanNN (healthy subjects and patients after HD), showing no association with the renal disease condition in itself. In conclusion, as in healthy subjects, α1 of CRF patients correlates with meanNN after HD (indicating a more irregular-like HRV behavior at slower heart rates). This suggests that CRF patients with stable blood pressure preserve a regulatory adaptability despite a shifted setting point of the heart period (i.e., higher heart rate) in comparison with healthy subjects. © 2017 International Center for

  18. [Evaluation of therapy for dilated cardiomyopathy with heart failure by iodine-123 metaiodobenzylguanidine imaging: comparison with heart rate variability power spectral analysis].

    PubMed

    Li, S; Ikeda, J; Takita, T; Sekiguchi, Y; Demachi, J; Chikama, H; Goto, A; Shirato, K

    1998-11-01

    The relationship between the myocardial uptake of iodine-123 metaiodobenzylguanidine (123I-MIBG) and heart rate variability parameters has not been determined. This study determined the relationship between the change in myocardial uptake of 123I-MIBG and improvement in left ventricular function after treatment, to determine the usefulness of 123I-MIBG imaging to assess the effect of therapy on heart failure due to dilated cardiomyopathy (DCM). 123I-MIBG imaging and power spectral analysis of heart rate variability were performed before and after treatment in 17 patients with heart failure due to DCM. The following parameters were compared before and after treatment: New York Heart Association (NYHA) functional class, radiographic cardiothoracic ratio (CTR), blood pressure, echocardiographic data [left ventricular end-systolic (LVDs) and end-diastolic (LVDd) diameters, left ventricular ejection fraction (LVEF)], plasma concentrations of norepinephrine and epinephrine, heart rate variability power spectral analysis data [mean low frequency (MLF) and high frequency power (MHF)] and the myocardium to mediastinum activity ratio (MYO/M) obtained in early and late images, and washout rate calculated by anterior planar imaging of 123I-MIBG. The NYHA functional class, LVEF, LVDs, CTR, MLF and MHF improved after treatment. Early MYO/M and late MYO/M improved after treatment. The rate of increase in late MYO/M was positively correlated with the rate of improvement of LVEF after treatment. Furthermore, the late MYO/M was negatively correlated with MLF. Washout rate revealed no correlation with hemodynamic parameters. These findings suggest that late MYO/M is more useful than washout rate to assess the effect of treatment on heart failure due to DCM. Furthermore, the 123I-MIBG imaging and heart rate variability parameters are useful to assess the autonomic tone in DCM with heart failure.

  19. Main components and performances of the IMGC calibration facilities for liquid helium flow rate measurements

    NASA Astrophysics Data System (ADS)

    Rivetti, A.; Martini, G.; Goria, R.; Lorefice, S.

    Within the framework of a National Project on superconductivity two facilities have been designed and built at the Istituto di Metrologia 'G. Colonnetti' (IMGC) with the purpose of studying and calibrating liquid helium flowmeters in the range 1-20 g s -1 of liquid helium (LHe). After a brief description of these set-ups, this Paper examines in detail the solutions adopted in the design of the main calibration facility, particularly with regard to the circulating pump and the submerged driving motor. The latter has been devised for working only at LHe temperature, having an a.c. three-phase stator winding made of thin superconducting wire. The construction characteristics and operation conditions are discussed. As a flow rate reference, a new turbine flowmeter with its rotor magnetically suspended by the Meissner effect (described in another paper presented at the workshop), is used. A LHe flow rate transducer, based upon the measurement of the transit time of short thermal pulses, has been designed and tested with these facilities: the good results obtained using commercial low cost diodes as ΔT sensors are reported.

  20. Using Reading Strategies To Reduce the Failure Rate in the Content Area. Subject: Social Studies. Grade Level: 6-7-8.

    ERIC Educational Resources Information Center

    Dobbs, Olivett

    Content area reading instruction includes two elements: the information presented in subject matter text, and the plan that teachers use to help students understand the content. According to research and interviews with social studies teachers, there is a high failure rate in the social studies content area because children have problems…

  1. Corrigendum to: Multi-scale defect interactions in high-rate brittle material failure. Part I: Model formulation and application to AlON

    NASA Astrophysics Data System (ADS)

    Tonge, A. L.; Ramesh, K. T.

    2017-09-01

    A minor error was present in one equation in the original paper, ;Multi-scale defect interactions in high-rate brittle material failure. Part I: Model formulation and application to AlON; and in the corresponding computational implementation. The correction is provided here. None of the primary conclusions of the original paper are affected.

  2. Effect of Correlations of Component Failures and Cross-Connections of EDGs on Seismically Induced Core Damages of a Multi-Unit Site

    NASA Astrophysics Data System (ADS)

    Muramatsu, Ken; Liu, Qiao; Uchiyama, Tomoaki

    Aiming at proposing effective applications of seismic probabilistic safety assessment (PSA) for design and risk management of nuclear facilities, we conducted a preliminary seismic PSA study for a multi-unit site to examine core damage frequency (CDF) and core damage sequences with consideration of the effect of correlations of component failures. In addition, we also examined the effectiveness of an accident management measure, namely, cross-connections of emergency diesel generators (EDGs) between adjacent units in this study. Twin BWR-5 units of the same design were hypothesized to be located at the same site in this study and the CDF as well as the accident sequences of this two-unit site were analyzed by using SECOM2, a system reliability analysis code for seismic PSA. The results showed that the calculated CDF was dependent on the assumptions on the correlations of component failures. When the rules for assigning correlation coefficients of component responses defined in the NUREG-1150 program were adopted, the CDF of a single unit, the CDF of this two-unit site (the frequency of core damages of at least one unit at this site) and the frequency of simultaneous core damages of both units increased by factors of about 1.3, 1.2 and 2.3, respectively. In addition, it might be possible that the simultaneous core damages of both units are caused by different accident sequence pairs as well as the same sequence pairs. When cross-connections of EDGs between two units were available, the CDF of a single unit, the CDF of this two-unit site as well as the frequency of simultaneous core damages of both units decreased. In addition, the CDF of this two-unit site was smaller than the CDF of a single unit site. These results show that cross-connections of EDGs might be beneficial for a multi-unit site if the rules for assigning correlation coefficients defined in NUREG-1150 program are reasonable.

  3. Global Bi-ventricular endocardial distribution of activation rate during long duration ventricular fibrillation in normal and heart failure canines.

    PubMed

    Luo, Qingzhi; Jin, Qi; Zhang, Ning; Han, Yanxin; Wang, Yilong; Huang, Shangwei; Lin, Changjian; Ling, Tianyou; Chen, Kang; Pan, Wenqi; Wu, Liqun

    2017-04-13

    The objective of this study was to detect differences in the distribution of the left and right ventricle (LV & RV) activation rate (AR) during short-duration ventricular fibrillation (SDVF, <1 min) and long-duration ventricular fibrillation VF (LDVF, >1 min) in normal and heart failure (HF) canine hearts. Ventricular fibrillation (VF) was electrically induced in six healthy dogs (control group) and six dogs with right ventricular pacing-induced congestive HF (HF group). Two 64-electrode basket catheters deployed in the LV and RV were used for global endocardium electrical mapping. The AR of VF was estimated by fast Fourier transform analysis from each electrode. In the control group, the LV was activated faster than the RV in the first 20 s, after which there was no detectable difference in the AR between them. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the posterior LV was activated fastest, while the anterior was slowest. In the HF group, a detectable AR gradient existed between the two ventricles within 3 min of VF, with the LV activating more quickly than the RV. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the septum of the LV was activated fastest, while the anterior was activated slowest. A global bi-ventricular endocardial AR gradient existed within the first 20 s of VF but disappeared in the LDVF in healthy hearts. However, the AR gradient was always observed in both SDVF and LDVF in HF hearts. The findings of this study suggest that LDVF in HF hearts can be maintained differently from normal hearts, which accordingly should lead to the development of different management strategies for LDVF resuscitation.

  4. Heart Rate Recovery in the First Minute at the Six-Minute Walk Test in Patients with Heart Failure

    PubMed Central

    Lindemberg, Sabrina; Chermont, Sergio; Quintão, Mônica; Derossi, Milena; Guilhon, Sergio; Bernardez, Sabrina; Marchese, Luana; Martins, Wolney; Nóbrega, Antônio Claudio L.; Mesquita, Evandro Tinoco

    2014-01-01

    Background Heart rate recovery at one minute of rest (HRR1) is a predictor of mortality in heart failure (HF), but its prognosis has not been assessed at six-minute walk test (6MWT) in these patients. Objective This study aimed to determine the HRR1 at 6MWT in patients with HF and its correlation with six-minute walk distance (6MWD). Methods Cross-sectional, controlled protocol with 161 individuals, 126 patients with stable systolic HF, allocated into 2 groups (G1 and G2) receiving or not β-blocker and 35 volunteers in control group (G3) had HRR1 recorded at the 6MWT. Results HRR1 and 6MWD were significantly different in the 3 groups. Mean values of HRR1 and 6MWD were: HRR1 = 12 ± 14 beat/min G1; 18 ± 16 beat/min G2 and 21 ± 13 beat/min G3; 6MWD = 423 ± 102 m G1; 396 ± 101m G2 and 484 ± 96 m G3 (p < 0.05). Results showed a correlation between HRR1 and 6MWD in G1(r = 0.3; p = 0.04) and in G3(r = 0.4; p= 0.03), but not in G2 (r= 0.12; p= 0.48). Conclusion HRR1 response was attenuated in patients using βB and showed correlation with 6MWD, reflecting better exercise tolerance. HRR1 after 6MWT seems to represent an alternative when treadmill tests could not be tolerated. PMID:24714794

  5. Variation exists in rates of admission to intensive care units for heart failure patients across hospitals in the United States

    PubMed Central

    Safavi, Kyan C.; Dharmarajan, Kumar; Kim, Nancy; Strait, Kelly M.; Li, Shu-Xia; Chen, Serene I.; Lagu, Tara; Krumholz, Harlan M.

    2013-01-01

    Background Despite increasing attention on reducing relatively costly hospital practices while maintaining the quality of care, few studies have examined how hospitals use the intensive care unit (ICU), a high-cost setting, for patients admitted with heart failure (HF). We characterized hospital patterns of ICU admission for patients with HF and determined their association with the use of ICU-level therapies and patient outcomes. Methods and Results We identified 166,224 HF discharges from 341 hospitals in the 2009–10 Premier Perspective® database. We excluded hospitals with <25 HF admissions, patients <18 years old, and transfers. We defined ICU as including medical ICU, coronary ICU, and surgical ICU. We calculated the percent of patients admitted directly to an ICU. We compared hospitals in the top-quartile (high ICU admission) with the remaining quartiles. The median percentage of ICU admission was 10% (Interquartile Range 6% to 16%; range 0% to 88%). In top-quartile hospitals, treatments requiring an ICU were used less often: percentage of ICU days receiving mechanical ventilation (6% top quartile versus 15% others), non-invasive positive pressure ventilation (8% versus 19%), vasopressors and/or inotropes (9% versus 16%), vasodilators (6% versus 12%), and any of these interventions (26% versus 51%). Overall HF in-hospital risk standardized mortality was similar (3.4% versus 3.5%; P = 0.2). Conclusions ICU admission rates for HF varied markedly across hospitals and lacked association with in-hospital risk-standardized mortality. Greater ICU use correlated with fewer patients receiving ICU interventions. Judicious ICU use could reduce resource consumption without diminishing patient outcomes. PMID:23355624

  6. Sleeping and resting respiratory rates in dogs and cats with medically-controlled left-sided congestive heart failure.

    PubMed

    Porciello, F; Rishniw, M; Ljungvall, I; Ferasin, L; Haggstrom, J; Ohad, D G

    2016-01-01

    Sleeping and resting respiratory rates (SRR and RRR, respectively) are commonly used to monitor dogs and cats with left-sided cardiac disease and to identify animals with left-sided congestive heart failure (L-CHF). Dogs and cats with subclinical heart disease have SRRmean values <30 breaths/min. However, little is known about SRR and RRR in dogs and cats with CHF that is well controlled with medical therapy. In this study, SRR and RRR were measured by the owners of 51 dogs and 22 cats with stable, well-controlled CHF. Median canine SRRmean was 20 breaths/min (7-39 breaths/min); eight dogs were ≥25 breaths/min and one dog only was ≥30 breaths/min. Canine SRRmean was unrelated to pulmonary hypertension or diuretic dose. Median feline SRRmean was 20 breaths/min (13-31 breaths/min); four cats were ≥25 breaths/min and only one cat was ≥30 breaths/min. Feline SRRmean was unrelated to diuretic dose. SRR remained stable during collection in both species with little day-to-day variability. The median canine RRRmean was 24 breaths/min (12-44 breaths/min), 17 were ≥25 breaths/min, seven were ≥30 breaths/min, two were >40 breaths/min. Median feline RRRmean was 24 breaths/min (15-45 breaths/min); five cats had RRRmean ≥25 breaths/min; one had ≥30 breaths/min, and two had ≥40 breaths/min. These data suggest that most dogs and cats with CHF that is medically well-controlled and stable have SRRmean and RRRmean <30 breaths/min at home. Clinicians can use these data to help determine how best to control CHF in dogs and cats.

  7. Reliability and validity of the subjective component of the American Orthopaedic Foot and Ankle Society clinical rating scales.

    PubMed

    Ibrahim, Talal; Beiri, Almoghera; Azzabi, Mohamed; Best, Alistair J; Taylor, Grahame J; Menon, Dipen K

    2007-01-01

    This study evaluates the criterion validity of the subjective component of the American Orthopaedic Foot and Ankle Society (AOFAS) clinical rating scales by correlating scores obtained with these rating scales to scores obtained with the Foot Function Index (FFI) in patients with foot and ankle conditions. To date, the AOFAS scoring scales have not been shown to provide valid information despite their popularity. The FFI, on the other hand, has previously been shown to provide valid information in regard to conditions affecting the foot and ankle. A moderately strong inverse criterion validity correlation (Pearson correlation coefficient = -0.68) was shown when preoperative patients were administered both the AOFAS and FFI questionnaires, and the resultant scores were compared. Test-retest reliability measurements showed no significant difference (P = .27) between preoperative AOFAS scale scores measured at least 2 weeks apart. Construct validity was shown (P = .006) when dependent preoperative and postoperative (at least 3 months) AOFAS scale scores were compared, indicative of the clinical rating scales' ability to discriminate and predict quality of life related to foot and ankle conditions. The moderate level of correlation, satisfactory degree of reliability, and responsiveness (ability to distinguish differences between preoperative and postoperative conditions in the same patient) observed in this study suggest that the subjective component of the AOFAS clinical rating scales provides quality-of-life information that conveys acceptable validity regarding conditions affecting the foot and ankle.

  8. Paracetamol-associated acute liver failure in Australian and New Zealand children: high rate of medication errors.

    PubMed

    Rajanayagam, J; Bishop, J R; Lewindon, P J; Evans, Helen M

    2015-01-01

    In children, paracetamol overdose due to deliberate self-poisoning, accidental exposure or medication errors can lead to paediatric acute liver failure and death. In Australia and New Zealand, the nature of ingestion and outcomes of paracetamol-associated paediatric acute liver failure have not been described. To describe the nature and outcomes of paracetamol-associated paediatric acute liver failure. Retrospective analysis of paracetamol-associated paediatric acute liver failure cases presenting 2002-2012. New Zealand and Queensland Paediatric Liver Transplant Services. 14 of 54 cases of paediatric acute liver failure were attributed to paracetamol, the majority were secondary to medication errors. 12 of the 14 children were under the age of 5 years. Seven children received doses in excess of 120 mg/kg/day. Many of the other children received either a double dose, too frequent administration, coadministration of other medicines containing paracetamol or regular paracetamol for up to 24 days. Three children underwent transplant. One of these and one other child died. In Australia and New Zealand, paracetamol overdose secondary to medication errors is the leading cause of paediatric acute liver failure. A review of regional safety practices surrounding paracetamol use in children is indicated. 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.

  9. Complication and failure rates in patients treated for chronic periodontitis and restored with single crowns on teeth and/or implants.

    PubMed

    Schmidlin, Kurt; Schnell, Natascha; Steiner, Stefanie; Salvi, Giovanni E; Pjetursson, Bjarni; Matuliene, Giedre; Zwahlen, Marcel; Brägger, Urs; Lang, Niklaus P

    2010-05-01

    To assess the biological and technical complication rates of single crowns on vital teeth (SC-V), endodontically treated teeth without post and core (SC-E), with a cast post and core (SC-PC) and on implants (SC-I). From 392 patients with chronic periodontitis treated and documented by graduate students during the period from 1978 to 2002, 199 were reexamined during 2005 for this retrospective cohort study, and 64 of these patients were treated with SCs. Statistical analysis included Kaplan-Meier survival functions and event rates per 100 years of object-time. Poisson regression was used to compare the four groups of crowns with respect to the incidence rate ratio of failures, and failures and complications combined over 10 years and the entire observation period. Forty-one (64%) female and 23 (36%) male patients participated in the reexamination. At the time of seating the crowns, the mean patient age was 46.8 (range 24-66.3) years. One hundred and sixty-eight single unit crowns were incorporated. Their mean follow-up time was 11.8 (range 0.8-26.4) years. During the time of observation, 22 biological and 11 technical complications occurred; 19 SC were lost. The chance for SC-V (56) to remain free of any failure or complication was 89.3% (95% confidence interval [CI] 76.1-95.4) after 10 years, 85.8% (95% CI 66-94.5) for SC-E (34), 75.9% for SC-PC (39), (95% CI 58.8-86.7) and 66.2% (95% CI 45.1-80.7) for SC-I (39). Over 10 years, 95% of SC-I remained free of failure and demonstrated a cumulative incidence of failure or complication of 34%. Compared with SC-E, SC-I were 3.5 times more likely to yield failures or complications and SC-PC failed 1.7 times more frequently than did SC-E. SC-V had the lowest rate of failures or complications over the 10 years. While SCs on vital teeth have the best prognosis, those on endodontically treated teeth have a slightly poorer prognosis over 10 years. Crowns on teeth with post and cores and implant-supported SCs displayed the

  10. Pirenzepine-sensitive component of forelimb vascular resistance and heart rate in cats.

    PubMed

    Stein, R; Bachoo, M; Polosa, C

    1995-07-14

    In vagotomized, midcollicular decerebrate, non-anesthetized cats, in which the preganglionic input to the stellate ganglion was intact and the right forelimb was autoperfused at constant flow, the muscarinic receptor antagonist pirenzepine (PZP, 50 micrograms/kg i.v.), which does not cross the blood-brain barrier, produced a decrease in forelimb perfusion pressure (FLPP), heart rate (HR) and systemic arterial pressure (SAP). Administration of the nicotinic receptor antagonist hexamethonium (30 mg/kg i.v.) after PZP produced a further, larger drop in FLPP, HR and SAP. The dose of PZP used blocked the increase in FLPP and HR evoked by the muscarinic receptor agonist McN-A-343, but not the increase evoked by the nicotinic receptor agonist DMPP, when these drugs were injected into the arterial supply of the ganglion. Following administration of phentolamine and propranolol (2 mg/kg i.v. of each) which caused bradycardia and forelimb vasodilation, PZP had no effect on FLPP and HR. This finding suggests that PZP decreases sympathetic tone in resistance vessels and in the heart. Pirenzepine did not depress the forelimb vasoconstriction and the cardioacceleration evoked by electrical stimulation of the postganglionic vertebral and inferior cardiac nerves, respectively, suggesting that PZP does not act at the neuro-effector junctions. On the other hand, PZP blocked the forelimb vasoconstriction and the cardioacceleration produced by stimulating the preganglionic input of the stellate ganglion in presence of hexamethonium (30 mg/kg i.v.), indicating the stellate ganglion as the likely site of action of the drug. These findings suggest that the ganglion cell firing that underlies the sympathetic tone of cardiovascular effector cells is generated, in part, by a muscarinic, PZP-sensitive, synaptic mechanism.

  11. High rate of virological failure and low rate of switching to second-line treatment among adolescents and adults living with HIV on first-line ART in Myanmar, 2005-2015

    PubMed Central

    Harries, Anthony D.; Kumar, Ajay M. V.; Oo, Myo Minn; Kyaw, Khine Wut Yee; Win, Than; Aung, Thet Ko; Min, Aung Chan; Oo, Htun Nyunt

    2017-01-01

    Background The number of people living with HIV on antiretroviral treatment (ART) in Myanmar has been increasing rapidly in recent years. This study aimed to estimate rates of virological failure on first-line ART and switching to second-line ART due to treatment failure at the Integrated HIV Care program (IHC). Methods Routinely collected data of all adolescent and adult patients living with HIV who were initiated on first-line ART at IHC between 2005 and 2015 were retrospectively analyzed. The cumulative hazard of virological failure on first-line ART and switching to second-line ART were estimated. Crude and adjusted hazard ratios were calculated using the Cox regression model to identify risk factors associated with the two outcomes. Results Of 23,248 adults and adolescents, 7,888 (34%) were tested for HIV viral load. The incidence rate of virological failure among those tested was 3.2 per 100 person-years follow-up and the rate of switching to second-line ART among all patients was 1.4 per 100 person-years follow-up. Factors associated with virological failure included: being adolescent; being lost to follow-up at least once; having WHO stage 3 and 4 at ART initiation; and having taken first-line ART elsewhere before coming to IHC. Of the 1032 patients who met virological failure criteria, 762 (74%) switched to second-line ART. Conclusions We found high rates of virological failure among one third of patients in the cohort who were tested for viral load. Of those failing virologically on first-line ART, about one quarter were not switched to second-line ART. Routine viral load monitoring, especially for those identified as having a higher risk of treatment failure, should be considered in this setting to detect all patients failing on first-line ART. Strategies also need to be put in place to prevent treatment failure and to treat more of those patients who are actually failing. PMID:28182786

  12. High rate of virological failure and low rate of switching to second-line treatment among adolescents and adults living with HIV on first-line ART in Myanmar, 2005-2015.

    PubMed

    Kyaw, Nang Thu Thu; Harries, Anthony D; Kumar, Ajay M V; Oo, Myo Minn; Kyaw, Khine Wut Yee; Win, Than; Aung, Thet Ko; Min, Aung Chan; Oo, Htun Nyunt

    2017-01-01

    The number of people living with HIV on antiretroviral treatment (ART) in Myanmar has been increasing rapidly in recent years. This study aimed to estimate rates of virological failure on first-line ART and switching to second-line ART due to treatment failure at the Integrated HIV Care program (IHC). Routinely collected data of all adolescent and adult patients living with HIV who were initiated on first-line ART at IHC between 2005 and 2015 were retrospectively analyzed. The cumulative hazard of virological failure on first-line ART and switching to second-line ART were estimated. Crude and adjusted hazard ratios were calculated using the Cox regression model to identify risk factors associated with the two outcomes. Of 23,248 adults and adolescents, 7,888 (34%) were tested for HIV viral load. The incidence rate of virological failure among those tested was 3.2 per 100 person-years follow-up and the rate of switching to second-line ART among all patients was 1.4 per 100 person-years follow-up. Factors associated with virological failure included: being adolescent; being lost to follow-up at least once; having WHO stage 3 and 4 at ART initiation; and having taken first-line ART elsewhere before coming to IHC. Of the 1032 patients who met virological failure criteria, 762 (74%) switched to second-line ART. We found high rates of virological failure among one third of patients in the cohort who were tested for viral load. Of those failing virologically on first-line ART, about one quarter were not switched to second-line ART. Routine viral load monitoring, especially for those identified as having a higher risk of treatment failure, should be considered in this setting to detect all patients failing on first-line ART. Strategies also need to be put in place to prevent treatment failure and to treat more of those patients who are actually failing.

  13. Failure characteristics of 6061/AI2O3/15 ρ and 2014/AI2O33/15 ρ composites as a function of loading rate

    NASA Astrophysics Data System (ADS)

    Lou, B. Y.; Huang, J. C.

    1996-10-01

    The effects of loading rate on the toughness and fracture mechanisms of two cast 6061/Al2O3/15p and 2014/Al2O3/15p composites under the as-worked (AW) and AW + T6 conditions have been examined. The quasistatic bending and high-rate impact tests were conducted over strain rates from 5 X 10-4 to 1 X 103 s-1 using screw-driven or servohydraulic high-rate systems. The results showed that the peak load P max, specimen deflection d, specimen lateral expansion fraction Δ w, crack initiation energy E i, propagation energy E p, total fracture energy E t and deformation zone all tended to increase with increasing strain rate. Under quasistatic loading, the composites failed predominantly by ma-trix/reinforcement interface decohesion. As the loading rate increased, reinforcement failure became the major failure mechanism. Differences in the effect of matrix microstructure and stress state on the fracture properties also are discussed. In comparing the fracture modes in the AW and AW + T6 specimens, the latter showed a higher tendency toward particle cracking. Based on mechanical data, the degree of specimen deflection and expansion and fracture modes, the AW composites exhibited a higher strain-rate dependence. The T6 specimens, due to their intrinsicly more brittle nature, appeared to be less influenced by loading rate over the strain-rate range examined.

  14. Do Insect Populations Die at Constant Rates as They Become Older? Contrasting Demographic Failure Kinetics with Respect to Temperature According to the Weibull Model

    PubMed Central

    Damos, Petros; Soulopoulou, Polyxeni

    2015-01-01

    Temperature implies contrasting biological causes of demographic aging in poikilotherms. In this work, we used the reliability theory to describe the consistency of mortality with age in moth populations and to show that differentiation in hazard rates is related to extrinsic environmental causes such as temperature. Moreover, experiments that manipulate extrinsic mortality were used to distinguish temperature-related death rates and the pertinence of the Weibull aging model. The Newton-Raphson optimization method was applied to calculate parameters for small samples of ages at death by estimating the maximum likelihoods surfaces using scored gradient vectors and the Hessian matrix. The study reveals for the first time that the Weibull function is able to describe contrasting biological causes of demographic aging for moth populations maintained at different temperature regimes. We demonstrate that at favourable conditions the insect death rate accelerates as age advances, in contrast to the extreme temperatures in which each individual drifts toward death in a linear fashion and has a constant chance of passing away. Moreover, slope of hazard rates shifts towards a constant initial rate which is a pattern demonstrated by systems which are not wearing out (e.g. non-aging) since the failure, or death, is a random event independent of time. This finding may appear surprising, because, traditionally, it was mostly thought as rule that in aging population force of mortality increases exponentially until all individuals have died. Moreover, in relation to other studies, we have not observed any typical decelerating aging patterns at late life (mortality leveling-off), but rather, accelerated hazard rates at optimum temperatures and a stabilized increase at the extremes.In most cases, the increase in aging-related mortality was simulated reasonably well according to the Weibull survivorship model that is applied. Moreover, semi log- probability hazard rate model

  15. Is heart rate a risk marker in patients with chronic heart failure and concomitant atrial fibrillation? Results from the MAGGIC meta-analysis.

    PubMed

    Simpson, Joanne; Castagno, Davide; Doughty, Rob N; Poppe, Katrina K; Earle, Nikki; Squire, Iain; Richards, Mark; Andersson, Bert; Ezekowitz, Justin A; Komajda, Michel; Petrie, Mark C; McAlister, Finlay A; Gamble, Greg D; Whalley, Gillian A; McMurray, John J V

    2015-11-01

    To investigate the relationship between heart rate and survival in patients with heart failure (HF) and coexisting atrial fibrillation (AF). Patients with AF included in the Meta-analysis Global Group in Chronic Heart Failure (MAGGIC) meta-analysis were the main focus of this analysis (3259 patients from 17 studies). The outcome was all-cause mortality at 3 years. Heart rate was analysed as a categorical (tertiles; T1 ≤77 b.p.m., T2 78-98 b.p.m., T3 ≥98 b.p.m.) and continuous variable. Cox proportional hazard models were used to compare the risk of all-cause death between tertiles of baseline heart rate. Patients in the highest tertile were more often female, less likely to have an ischaemic aetiology or diabetes, had a lower ejection fraction but higher blood pressure and New York Heart Association (NYHA) class. Higher heart rate was associated with higher mortality in patients with sinus rhythm (SR) but not in those in AF. In patients with heart failure and reduced ejection fraction (HF-REF) and AF, death rates per 100 patient years were lowest in the highest heart rate tertile (T1 18.9 vs. T3 15.9) but this difference was not statistically significant (P = 0.10). In patients with heart failure and preserved ejection fraction (HF-PEF), death rates per 100 patient years were highest in the highest heart rate tertile (T1 14.6 vs. T3 16.0, P = 0.014). However, after adjustment for other important prognostic variables, higher heart rate was no longer associated with higher mortality in HF-PEF (or HF-REF). In this meta-analysis of patients with HF, heart rate does not have the same prognostic significance in patients in AF as it does in those in SR, irrespective of ejection fraction or treatment with beta-blocker. © 2015 The Authors European Journal of Heart Failure © 2015 European Society of Cardiology.

  16. Do Insect Populations Die at Constant Rates as They Become Older? Contrasting Demographic Failure Kinetics with Respect to Temperature According to the Weibull Model.

    PubMed

    Damos, Petros; Soulopoulou, Polyxeni

    2015-01-01

    Temperature implies contrasting biological causes of demographic aging in poikilotherms. In this work, we used the reliability theory to describe the consistency of mortality with age in moth populations and to show that differentiation in hazard rates is related to extrinsic environmental causes such as temperature. Moreover, experiments that manipulate extrinsic mortality were used to distinguish temperature-related death rates and the pertinence of the Weibull aging model. The Newton-Raphson optimization method was applied to calculate parameters for small samples of ages at death by estimating the maximum likelihoods surfaces using scored gradient vectors and the Hessian matrix. The study reveals for the first time that the Weibull function is able to describe contrasting biological causes of demographic aging for moth populations maintained at different temperature regimes. We demonstrate that at favourable conditions the insect death rate accelerates as age advances, in contrast to the extreme temperatures in which each individual drifts toward death in a linear fashion and has a constant chance of passing away. Moreover, slope of hazard rates shifts towards a constant initial rate which is a pattern demonstrated by systems which are not wearing out (e.g. non-aging) since the failure, or death, is a random event independent of time. This finding may appear surprising, because, traditionally, it was mostly thought as rule that in aging population force of mortality increases exponentially until all individuals have died. Moreover, in relation to other studies, we have not observed any typical decelerating aging patterns at late life (mortality leveling-off), but rather, accelerated hazard rates at optimum temperatures and a stabilized increase at the extremes.In most cases, the increase in aging-related mortality was simulated reasonably well according to the Weibull survivorship model that is applied. Moreover, semi log- probability hazard rate model

  17. Altered Heart Rate Variability in Spontaneously Hypertensive Rats Is Associated with Specific Particulate Matter Components in Detroit, Michigan

    PubMed Central

    Rohr, Annette C.; Kamal, Ali; Morishita, Masako; Mukherjee, Bhramar; Keeler, Gerald J.; Harkema, Jack R.; Wagner, James G.

    2011-01-01

    Background Exposure to fine particulate matter [aerodynamic diameter ≤ 2.5 μm (PM2.5)] is linked to adverse cardiopulmonary health effects; however, the responsible constituents are not well defined. Objective We used a rat model to investigate linkages between cardiac effects of concentrated ambient particle (CAP) constituents and source factors using a unique, highly time-resolved data set. Methods Spontaneously hypertensive rats inhaled Detroit Michigan, CAPs during summer or winter (2005–2006) for 13 consecutive days. Electrocardiogram data were recorded continuously, and heart rate (HR) and heart rate variability (HRV) metrics were derived. Extensive CAP characterization, including use of a Semicontinuous Elements in Aerosol Sampler (SEAS), was performed, and positive matrix factorization was applied to investigate source factors. Results Mean CAP exposure concentrations were 518 μg/m3 and 357 μg/m3 in the summer and winter, respectively. Significant reductions in the standard deviation of the normal-to-normal intervals (SDNN) in the summer were strongly associated with cement/lime, iron/steel, and gasoline/diesel factors, whereas associations with the sludge factor and components were less consistent. In winter, increases in HR were associated with a refinery factor and its components. CAP-associated HR decreases in winter were linked to sludge incineration, cement/lime, and coal/secondary sulfate factors and most of their associated components. Specific relationships for increased root mean square of the standard deviation of successive normal-to-normal intervals (RMSSD) in winter were difficult to determine because of lack of consistency between factors and associated constituents. Conclusions Our results indicate that specific modulation of cardiac function in Detroit was most strongly linked to local industrial sources. Findings also highlight the need to consider both factor analytical results and component-specific results when interpreting

  18. Azimilide causes reverse rate-dependent block while reducing both components of delayed-rectifier current in canine ventricular myocytes.

    PubMed

    Gintant, G A

    1998-06-01

    Most class III antiarrhythmic drugs reduce the rapidly activating component of delayed-rectifier current (IKr) without affecting the slowly activating component (IKs). Recently the novel antiarrhythmic agent azimilide (NE-10064) was reported to enhance IKs at low (nanomolar) concentrations and to block both IKr and IKs at higher (micromolar) concentrations. Further to understand the electrophysiologic effects of azimilide, we compared its effects on IKr and IKs (by using whole cell clamp techniques) and action potentials (microelectrode and perforated-patch techniques) on canine ventricular myocytes. A lower azimilide concentration (50 nM) did not enhance IKs. In contrast, a therapeutic azimilide concentration (2 microM) was equieffective in reducing IKr (300-ms isochrones) and IKs (3-s isochrones) by approximately 40% during depolarizing test pulses, as well as reducing IKr (38% decrease) and IKs (33% decrease) tail currents on repolarization. Block of IKs was independent of voltage at positive test potentials. In action-potential studies, 50 nM azimilide had no effect on the action-potential duration (APD), whereas 2 microM azimilide delayed repolarization and caused reverse rate-dependent effects on the APD. Whereas the extent of APD prolongation by azimilide was not correlated with the drug-free APD, azimilide preferentially exaggerated the APD-rate relationship of myocytes displaying the steepest APD-rate relationship under drug-free conditions. In conclusion, therapeutic concentrations of azimilide that cause comparable reduction of canine ventricular IKr and IKs exert reverse rate-dependent effects, which are dependent on the steepness of the APD-rate relationship.

  19. The effect of local bone mineral density on the rate of mechanical failure after surgical treatment of distal radius fractures: a prospective multicentre cohort study including 249 patients.

    PubMed

    Rikli, Daniel; Daniel, Rikli; Goldhahn, Joerg; Joerg, Goldhahn; Käch, Kurt; Kurt, Käch; Voigt, Christine; Christine, Voigt; Platz, Andreas; Andreas, Platz; Hanson, Beate; Beate, Hanson

    2015-02-01

    The aim of this prospective, multicentre study was to evaluate the influence of local bone mineral density (BMD) on the rate of mechanical failure after locking plate fixation of closed distal radius fractures. Between June 2007 and April 2010, 230 women and 19 men with a mean age of 67 years were enrolled. Dual energy X-ray absorptiometry measurements for BMD of the contralateral distal radius were made at 6 weeks post-surgery. Follow-up evaluations at 6 weeks, 3 months and 1 year included wrist mobility and strength as well as standard radiographs. Any local bone/fracture or implant/surgery-related complications were documented. The Disability of the Arm, Shoulder, and Hand (DASH), Patient Rated Wrist Evaluation (PRWE), and EuroQol-5D scores were also recorded at the nominated time points. Nine patients were reported with mechanical failure at an estimated risk of 3.6 %. The BMD measurements were generally low for the study population with no difference between patients with (0.561 g/cm(2)) and without (0.626 g/cm(2)) mechanical failure (p = 0.148). None of the patients achieved their pre-injury functional level and quality of life status after 1 year. 1-year DASH and PRWE scores as well as the difference in maximum grip strength of the affected wrist relative to the contralateral side were significantly higher for patients with mechanical failure (p ≤ 0.036). Our study could not identify a clear association between bone mineral density status and the risk of mechanical failure. Although the risk for mechanical failure after treatment of distal radius fractures with palmar locking plates is low, these complications must be avoided to prevent negative impact on long-term patient functional and quality of life outcome.

  20. Heart Failure

    MedlinePlus

    ... version of this page please turn Javascript on. Heart Failure What is Heart Failure? In heart failure, the heart cannot pump enough ... failure often experience tiredness and shortness of breath. Heart Failure is Serious Heart failure is a serious and ...

  1. Common Cause Failure Modeling

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Britton, Paul; Ring, Rob; Novack, Steven D.

    2015-01-01

    Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFS are a set of dependent type of failures that can be caused by: system environments; manufacturing; transportation; storage; maintenance; and assembly, as examples. Since there are many factors that contribute to CCFs, the effects can be reduced, but they are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and CCF (dependent) failure and data is limited, especially for launch vehicles. The Probabilistic Risk Assessment (PRA) of NASA's Safety and Mission Assurance Directorate at Marshall Space Flight Center (MFSC) is using generic data from the Nuclear Regulatory Commission's database of common cause failures at nuclear power plants to estimate CCF due to the lack of a more appropriate data source. There remains uncertainty in the actual magnitude of the common cause risk estimates for different systems at this stage of the design. Given the limited data about launch vehicle CCF and that launch vehicles are a highly redundant system by design, it is important to make design decisions to account for a range of values for independent and CCFs. When investigating the design of the one-out-of-two component redundant system for launch vehicles, a response surface was constructed to represent the impact of the independent failure rate versus a common cause beta factor effect on a system's failure probability. This presentation will define a CCF and review estimation calculations. It gives a summary of reduction methodologies and a review of examples of historical CCFs. Finally, it presents the response surface and discusses the results of the different CCFs on the reliability of a one-out-of-two system.

  2. Common Cause Failure Modeling

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Britton, Paul; Ring, Rob; Novack, Steven D.

    2016-01-01

    Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFS are a set of dependent type of failures that can be caused by: system environments; manufacturing; transportation; storage; maintenance; and assembly, as examples. Since there are many factors that contribute to CCFs, the effects can be reduced, but they are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and CCF (dependent) failure and data is limited, especially for launch vehicles. The Probabilistic Risk Assessment (PRA) of NASA's Safety and Mission Assurance Directorate at Marshal Space Flight Center (MFSC) is using generic data from the Nuclear Regulatory Commission's database of common cause failures at nuclear power plants to estimate CCF due to the lack of a more appropriate data source. There remains uncertainty in the actual magnitude of the common cause risk estimates for different systems at this stage of the design. Given the limited data about launch vehicle CCF and that launch vehicles are a highly redundant system by design, it is important to make design decisions to account for a range of values for independent and CCFs. When investigating the design of the one-out-of-two component redundant system for launch vehicles, a response surface was constructed to represent the impact of the independent failure rate versus a common cause beta factor effect on a system's failure probability. This presentation will define a CCF and review estimation calculations. It gives a summary of reduction methodologies and a review of examples of historical CCFs. Finally, it presents the response surface and discusses the results of the different CCFs on the reliability of a one-out-of-two system.

  3. Ivabradine treatment prevents dobutamine-induced increase in heart rate in patients with acute decompensated heart failure.

    PubMed

    Cavusoglu, Yuksel; Mert, Ugur; Nadir, Aydin; Mutlu, Fezan; Morrad, Bektas; Ulus, Taner

    2015-09-01

    Ivabradine is a heart rate (HR)-lowering agent acting by inhibiting the If-channel. Dobutamine does increase the HR and has some deleterious effects on myocardium. So, we aimed to evaluate whether ivabradine treatment blunts a dobutamine-induced increase in HR. The main study population consisted of 58 acute decompensated heart failure patients requiring inotropic support with left-ventricular ejection fraction below 35%, who were randomized to ivabradine (n = 29) or control (n = 29). All patients underwent Holter recording for 6 h and then dobutamine was administered at incremental doses of 5, 10 and 15 μg/kg/min, with 6-h steps. Holter recording was continued during dobutamine infusion. Ivabradine 7.5 mg was given at the initiation of dobutamine and readministered at 12 h of infusion. Also, a nonrandomized beta-blocker group with 15 patients receiving beta-blocker was included in the analysis. Control and beta-blocker groups did not receive ivabradine. In the control group, mean HR gradually and significantly increased at each step of dobutamine infusion (81 ± 11, 90 ± 16, 97 ± 14 and 101 ± 16 b.p.m., respectively; P = 0.001), whereas no significant increase in HR was observed in the ivabradine group (82 ± 17, 82 ± 15, 85 ± 14 and 83 ± 12 b.p.m., respectively; P = 0.439). Mean HR was also found to significantly increase during dobutamine infusion in the beta-blocker group (75 ± 13, 82 ± 13, 86 ± 14 and 88 ± 13 b.p.m., respectively; P = 0.001). The median increase in HR from baseline was significantly higher in the control group compared to those in the ivabradine group (5 vs. 2 b.p.m.; P = 0.007 at first step, 13 vs. 5 b.p.m.; P = 0.001 at second step and 18 vs. 6 b.p.m.; P = 0.0001 at third step of dobutamine, respectively). Ivabradine treatment prevents dobutamine-induced increase in HR and may be useful in reducing HR-related adverse effects of

  4. Double blind placebo controlled trial of short term transdermal scopolamine on heart rate variability in patients with chronic heart failure.

    PubMed Central

    Venkatesh, G.; Fallen, E. L.; Kamath, M. V.; Connolly, S.; Yusuf, S.

    1996-01-01

    OBJECTIVE: To test the hypothesis that short term application of transdermal scopolamine increases heart rate variability (HRV) and restores sympathovagal balance in patients with stable congestive heart failure (CHF). DESIGN: A double blind placebo controlled crossover study. SETTING: Tertiary referral centre. PATIENTS: Twelve patients (mean age 66 (10)) with New York Heart Association class II-IV CHF. All patients had coronary artery disease (mean left ventricular ejection fraction 26.7 (8.9) %). INTERVENTION: Patients were randomly assigned to receive either a placebo skin patch or a transdermal scopolamine patch (Transderm, 0.05 mg/h). Patches remained in place for 48 hours with a 24 hour washout period before crossover. OUTCOME MEASURES: HRV was derived from (a) 24 hour time domain indices (mean RR interval, standard deviation of interbeat interval, and the baseline width of the frequency distribution of RR intervals) and (b) short data set (2.2 mm) power spectral measurements using autoregressive modelling. Autospectral measures were performed in both resting supine and standing (orthostatic) states. The 24 hour Holter record was obtained during the second day of patch application. RESULTS: There was a small but significant (P < 0.05) increase in all time domain HRV variables with scopolamine. There was a paradoxical fall in low frequency (LF) spectral power induced by orthostasis during baseline (-30%) and placebo (-34%) states. Conversely, scopolamine was associated with a 14% increase in LF power during orthostatic stress. Scopolamine thus significantly reduced the orthostatic fall in LF (P < 0.01) compared with either baseline or placebo values. No difference in circadian rhythm was seen between the scopolamine and placebo treatment periods. However, the abrupt fall in the high frequency (vagal) power during the early morning sleep-wake hours was reduced by scopolamine. Scopolamine was also associated with a significant rightward shift in the resting LF

  5. Heart rate variability and n-3 fatty acids in patients with chronic renal failure--a pilot study.

    PubMed

    Christensen, J H; Aarøe, J; Knudsen, N; Dideriksen, K; Kornerup, H J; Dyerberg, J; Schmidt, E B

    1998-02-01

    Patients with chronic renal failure (CRF) often have autonomic cardiac dysfunction, which can be assessed by measuring heart rate variability (HRV). This dysfunction prediposes the patients to sudden cardiac death. This study describes 24-hour HRV in patients with CRF compared to HRV in patients with a previous myocardial infarction (MI). Furthermore, associations between HRV in patients with CRF and the content of n-3 polyunsaturated fatty acids (PUFA) in cell membranes were examined, because n-3 PUFA may improve HRV. Twenty-nine patients with CRF treated with dialysis were enrolled. A 24-hour Holter recording was obtained at baseline and the HRV variables, RR (= mean of all normal RR intervals during the 24-hour recording) and SDNN (= standard deviation of all normal RR intervals in the entire 24-hour recording) were analyzed. Also, granulocyte fatty acid composition was determined. The patients were allocated to dietary supplementation with either 5.2 g of n-3 PUFA or a placebo oil (olive oil) daily for 12 weeks in a double-blind design. At the end of the supplementation period the Holter recording and blood sampling were repeated. At baseline the CRF patients' mean SDNN ws 86 ms compared to 118 ms (p < 0.01) in patients with a previous MI. After supplementation with either n-3 PUFA or placebo a highly significant correlation was observed between the content of n-3 PUFA in cell membranes and HRV (r = 0.71, p < 0.01). Furthermore, when the patients were dichotomized according to their mean SDNN, it was found, that those with the highest SDNN had a higher content of n-3 PUFA in cell membranes compared to those with the lowest SDNN (7.8% vs 4.2%, p < 0.05). In conclusion, HRV was decreased in CRF patients indicating a cardiovascular autonomic dysfunction. The positive correlation between the n-3 PUFA content in cell membranes and HRV suggests that the effects of an increased intake of n-3 PUFA in CRF patients should be further studied.

  6. [Values of the sperm deformity index, acrosome abnormity rate, and sperm DNA fragmentation index of optimized sperm in predicting IVF fertilization failure].

    PubMed

    Jiang, Wei-jie; Jin, Fan; Zhou, Li-ming

    2016-02-01

    To investigate the values of the sperm deformity index (SDI), acrosome abnormity rate (AAR), and DNA fragmentation index (DFI) of optimized sperm in the prediction of fertilization failure (fertilization rate < 25%) in conventional in vitro fertilization (IVF). We selected 695 cycles of conventional IVF for pure oviductal infertility in this study, including 603 cycles of normal fertilization and 92 cycles of fertilization failure. On the day of oocyte retrieval, we examined sperm morphology, acrosome morphology, and DNA fragmentation using the Diff-Quik, PSA-FITC and SCD methods. We established the joint predictor (JP) by logistic equation and analyzed the values of different parameters in predicting fertilization failure with the receiver operating characteristic (ROC) curve. The fertilization rate was negatively correlated with SDI (r = - 0.07; P = 0.03), AAR (r = -0.49; P < 0.01), and DFI (r = -0. 21; P < 0.01). The SDI, AAR, and DFI in the normal fertilization group were 1.24 ± 0.20, (7.75 ± 2.28)%, and (7.87 ± 3.15)%, and those in the fertilization failure group were 1.42 ± 0.15, (12.02 ± 3.06)%, and (13.32 ± 4.13)%, respectively, all with statistically significant differences between the two groups (P < 0.05). SDI, AAR, and DFI were all risk factors of fertilization failure ( OR = 2.68, 14.11, and 3.85; P = 0.01, < 0.01, and < 0.01). The areas under the ROC curves for SDI, AAR, DFI, and JP were 0.651 ± 0.033, 0.895 ± 0.019, 0.789 ± 0.022, and 0.915 ± 0.017, respectively. According to the Youden index, the optimal cut-off values of SDI, AAR, and DFI obtained for the prediction of fertilization failure were approximately 1.45, 10%, and 12%. The SDI, AAR and DFI of optimized sperm are closely associated with the fertilization rate, and all have the value for predicting fertilization failure in IVF. The AAR is more valuable than the other single predictors, but JP is more effective than the AAR.

  7. Exposures to PM₂.₅ components and heart rate variability in taxi drivers around the Beijing 2008 Olympic Games.

    PubMed

    Wu, Shaowei; Deng, Furong; Niu, Jie; Huang, Qinsheng; Liu, Youcheng; Guo, Xinbiao

    2011-06-01

    Carbonaceous and metallic components of particles have been shown to play a role in particles' effects on cardiac autonomic function as measured by heart rate variability (HRV). Previously we reported the association of HRV with marked changes in traffic-related particulate air pollution around the Beijing 2008 Olympic Games in a panel of taxi drivers. We further investigated the relationship between exposures to the carbonaceous and metallic components of traffic-related particles and HRV in the same population. Repeated measurements of in-car exposures to particulate matter ≤ 2.5 μm in aerodynamic diameter (PM₂.₅), carbon monoxide and nitrogen oxides were conducted in a group of 14 taxi drivers for one work shift in four study periods around the Beijing 2008 Olympics. The quantities of organic/elemental carbons and 27 elements of the in-car PM₂.₅ mass were determined laboratorially. Linear mixed-effects models were used to evaluate the impact of exposures to different PM₂.₅ components on HRV while controlling for potential confounders. Taxi drivers' exposures to in-car PM₂.₅ and its components showed dramatic changes across the four study periods around the Beijing 2008 Olympics. Differences in associations of in-car PM₂.₅ components with HRV were found. An interquartile range (IQR: 917.9 ng/m³) increase in calcium was associated with a 5.48 millisecond [ms, 95% confidence interval (CI): 0.71, 10.24] increase in standard deviations of normal-to-normal (SDNN) intervals, while an IQR (4.1 ng/m³) increase in nickel was associated with a 1.53 ms (95% CI: 0.14, 2.92) increase in SDNN index. Additionally, a decline of 8.11 ms (95% CI: -15.26, -0.97) in SDNN per IQR (481.4 ng/m³) increase in iron was also found. The results support associations of PM₂.₅ metallic components with HRV in younger healthy individuals. Future studies are needed to clarify the interaction among different PM₂.₅ components or the role of PM₂.₅ mixtures

  8. Site-Directed Chemical Mutations on Abzymes: Large Rate Accelerations in the Catalysis by Exchanging the Functionalized Small Nonprotein Components.

    PubMed

    Ishikawa, Fumihiro; Shirahashi, Masato; Hayakawa, Hiroshi; Yamaguchi, Asako; Hirokawa, Takatsugu; Tsumuraya, Takeshi; Fujii, Ikuo

    2016-10-21

    Taking advantage of antibody molecules to generate tailor-made binding sites, we propose a new class of protein modifications, termed as "site-directed chemical mutation." In this modification, chemically synthesized catalytic components with a variety of steric and electronic properties can be noncovalently and nongenetically incorporated into specific sites in antibody molecules to induce enzymatic activity. Two catalytic antibodies, 25E2 and 27C1, possess antigen-combining sites which bind catalytic components and act as apoproteins in catalytic reactions. By simply exchanging these components, antibodies 25E2 and 27C1 can catalyze a wide range of chemical transformations including acyl-transfer, β-elimination, aldol, and decarboxylation reactions. Although both antibodies were generated with the same hapten, phosphonate diester 1, they showed different catalytic activity. When phenylacetic acid 4 was used as the catalytic component, 25E2 efficiently catalyzed the elimination reaction of β-haloketone 2, whereas 27C1 showed no catalytic activity. In this work, we focused on the β-elimination reaction and examined the site-directed chemical mutation of 27C1 to induce activity and elucidate the catalytic mechanism. Molecular models showed that the cationic guanidyl group of Arg(H52) in 27C1 makes a hydrogen bond with the P═O oxygen in the hapten. This suggested that during β-elimination, Arg(H52) of 27C1 would form a salt bridge with the carboxylate of 4, thus destroying reactivity. Therefore, we utilized site-directed chemical mutation to change the charge properties of the catalytic components. When amine components 7-10 were used, 27C1 efficiently catalyzed the β-elimination reaction. It is noteworthy that chemical mutation with secondary amine 8 provided extremely high activity, with a rate acceleration [(kcat/Km 2)/kuncat] of 1 000 000. This catalytic activity likely arises from the proximity effect, plus general-base catalysis associated the

  9. The prognostic significance of heart rate in patients hospitalized for heart failure with reduced ejection fraction in sinus rhythm: insights from the EVEREST (Efficacy of Vasopressin Antagonism in Heart Failure: Outcome Study With Tolvaptan) trial.

    PubMed

    Greene, Stephen J; Vaduganathan, Muthiah; Wilcox, Jane E; Harinstein, Matthew E; Maggioni, Aldo P; Subacius, Haris; Zannad, Faiez; Konstam, Marvin A; Chioncel, Ovidiu; Yancy, Clyde W; Swedberg, Karl; Butler, Javed; Bonow, Robert O; Gheorghiade, Mihai

    2013-12-01

    The purpose of this study was to characterize the relationship between heart rate and post-discharge outcomes in patients with hospitalization for heart failure (HHF) with reduced ejection fraction (EF) in sinus rhythm. A reduction in heart rate improves clinical outcomes in patients with chronic heart failure and in sinus rhythm, but the association between heart rate and post-discharge outcomes in patients with HHF is presently unclear. This post-hoc analysis of the EVEREST (Efficacy of Vasopressin Antagonism in Heart Failure: Outcome Study With Tolvaptan) trial examined 1,947 patients with HHF and EF ≤40% not in atrial fibrillation/flutter or pacemaker dependent. The median follow-up period was 9.9 months. At baseline, patients with a higher heart rate tended to be younger with lower EF and were more likely to have worse New York Heart Association functional class and higher natriuretic peptide levels. After adjustment for clinical risk factors, baseline heart rate was not predictive of all-cause mortality (p ≥ 0.066). However, at ≥70 beats/min, every 5-beat increase in 1-week post-discharge heart rate was independently associated with increased all-cause mortality (hazard ratio: 1.13 [95% confidence interval: 1.05 to 1.22]; p = 0.002). Similarly, every 5-beat increase ≥70 beats/min in 4-week post-discharge heart rate was predictive of all-cause mortality (hazard ratio: 1.12 [95% confidence interval: 1.05 to 1.19]; p = 0.001). In this large cohort of patients with HHF with reduced EF and in sinus rhythm, baseline heart rate did not correlate with all-cause mortality. In contrast, at ≥70 beats/min, higher heart rate in the early post-discharge period was independently predictive of death during subsequent follow-up. Further study of post-discharge heart rate as a potential therapeutic target in this high-risk population is encouraged. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  10. Risk-standardized Acute Admission Rates Among Patients With Diabetes and Heart Failure as a Measure of Quality of Accountable Care Organizations: Rationale, Methods, and Early Results

    PubMed Central

    Spatz, Erica S.; Lipska, Kasia J.; Dai, Ying; Bao, Haikun; Lin, Zhenqiu; Parzynski, Craig S.; Altaf, Faseeha K.; Joyce, Erin K.; Montague, Julia A.; Ross, Joseph S.; Bernheim, Susannah M.; Krumholz, Harlan M.; Drye, Elizabeth E.

    2017-01-01

    Background Population-based measures of admissions among patients with chronic conditions are important quality indicators of Accountable Care Organizations (ACOs), yet there are challenges in developing measures that enable fair comparisons among providers. Methods Based on consensus standards for outcome measure development and with expert and stakeholder input on methods decisions, we developed and tested two models of risk-standardized acute admission rates (RSAARs) for patients with diabetes and heart failure using 2010–2012 Medicare claims data. Model performance was assessed with deviance R-squared; score reliability was tested with intraclass correlation coefficient. We estimated RSAARs for 114 Shared Savings Program ACOs in 2012 and we assigned ACOs to 3 performance categories: no different, worse than, and better than the national rate. Results The diabetes and heart failure cohorts included 6.5 and 2.6 million Medicare fee-for-service (FFS) beneficiaries aged ≥65 years, respectively. Risk-adjustment variables were age, comorbidities and condition-specific severity variables, but not socioeconomic status or other contextual factors. We selected hierarchical negative binomial models with the outcome of acute, unplanned hospital admissions per 100 person-years. For the diabetes and heart failure measures respectively, the models accounted for 22% and 12% of the deviance in outcomes and score reliability was 0.89 and 0.77. For the diabetes measure, 51 (44.7%) ACOs were no different, 45 (39.5%) were better, and 18 (15.8%) were worse than the national rate. The distribution of performance for the heart failure measure was: 61 (53.5%);,37 (32.5%) and 16 (14.0%), respectively. Conclusion Measures of RSAARs for patients with diabetes and heart failure meet criteria for scientific soundness and reveal important variation in quality across ACOs. PMID:26918404

  11. Effects of Active Components of Fuzi and Gancao Compatibility on Bax, Bcl-2, and Caspase-3 in Chronic Heart Failure Rats

    PubMed Central

    Wang, Liqin; He, Yu; Zhang, Yuyan; Zhou, Huifen; Yu, Li

    2016-01-01

    Hypaconitine (HA) and glycyrrhetinic acid (GA) are active components of Fuzi (Aconitum carmichaelii) and Gancao (Glycyrrhiza uralensis Fisch); they have been used in compatibility for chronic heart failure (CHF) from ancient times. The purpose of the present research was to explore whether apoptosis pathways were related with the protective effects of HA + GA against CHF rats or not. The rats were progressed with transverse-aortic constriction (TAC) operation for 4 weeks to build the CHF state, and then the Digoxin (1 mg/kg), HA (2.07 mg/kg), GA (25 mg/kg), and HA (2.07 mg/kg) + GA (25 mg/kg) were orally administrated to rats for 1 week. The levels of BNP and cTnI in the plasma were decreased in the HA + GA group, and the heart/body weight ratio (H/B) and left ventricular (LV) parameters of transthoracic echocardiography were also declined; moreover, the expressions of Bax, Bcl-2, and caspase-3 were all improved in the HA + GA group than other groups in the immunohistochemistry and western blot methods. In general, the data suggested that Fuzi and Gancao compatibility could protect the CHF rats from apoptosis, which provided a strong evidence for further searching for mechanisms of them. PMID:28053643

  12. Relationship Between Changes in Pulse Pressure and Frequency Domain Components of Heart Rate Variability During Short-Term Left Ventricular Pacing in Patients with Cardiac Resynchronization Therapy.

    PubMed

    Urbanek, Bożena; Ruta, Jan; Kudryński, Krzysztof; Ptaszyński, Paweł; Klimczak, Artur; Wranicz, Jerzy Krzysztof

    2016-06-15

    BACKGROUND The aim of the study was to explore the relationship between changes in pulse pressure (PP) and frequency domain heart rate variability (HRV) components caused by left ventricular pacing in patients with implanted cardiac resynchronization therapy (CRT). MATERIAL AND METHODS Forty patients (mean age 63±8.5 years) with chronic heart failure (CHF) and implanted CRT were enrolled in the study. The simultaneous 5-minute recording of beat-to-beat arterial systolic and diastolic blood pressure (SBP and DBP) by Finometer and standard electrocardiogram with CRT switched off (CRT/0) and left ventricular pacing (CRT/LV) was performed. PP (PP=SBP-DBP) and low- and high-frequency (LF and HF) HRV components were calculated, and the relationship between these parameters was analyzed. RESULTS Short-term CRT/LV in comparison to CRT/0 caused a statistically significant increase in the values of PP (P<0.05), LF (P<0.05), and HF (P<0.05). A statistically significant correlation between ΔPP and ΔHF (R=0.7384, P<0.05) was observed. The ΔHF of 6 ms2 during short-term CRT/LV predicted a PP increase of ≥10% with 84.21% sensitivity and 85.71% specificity. CONCLUSIONS During short-term left ventricular pacing in patients with CRT, a significant correlation between ΔPP and ΔHF was observed. ΔHF ≥6 ms2 may serve as a tool in the selection of a suitable site for placement of a left ventricular lead.

  13. Consciously controlled breathing decreases the high-frequency component of heart rate variability by inhibiting cardiac parasympathetic nerve activity.

    PubMed

    Sasaki, Konosuke; Maruyama, Ryoko

    2014-01-01

    Heart rate variability (HRV), the beat-to-beat alterations in heart rate, comprises sympathetic and parasympathetic nerve activities of the heart. HRV analysis is used to quantify cardiac autonomic regulation. Since respiration could be a confounding factor in HRV evaluation, some studies recommend consciously controlled breathing to standardize the method. However, it remains unclear whether controlled breathing affects HRV measurement. We compared the effects of controlled breathing on HRV with those of spontaneous breathing. In 20 healthy volunteers, we measured respiratory frequency (f), tidal volume, and blood pressure (BP) and recorded electrocardiograms during spontaneous breathing (14.8 ± 0.7 breaths/min) and controlled breathing at 15 (0.25 Hz) and 6 (0.10 Hz) breaths/min. Compared to spontaneous breathing, controlled breathing at 0.25 Hz showed a higher heart rate and a lower high-frequency (HF) component, an index of parasympathetic nerve activity, although the f was the same. During controlled breathing at 0.10 Hz, the ratio of the low frequency (LF) to HF components (LF/HF), an index of sympathetic nerve activity, increased greatly and HF decreased, while heart rate and BP remained almost unchanged. Thus, controlled breathing at 0.25 Hz, which requires mental concentration, might inhibit parasympathetic nerve activity. During controlled breathing at 0.10 Hz, LF/HF increases because some HF subcomponents are synchronized with f and probably move into the LF band. This increment leads to misinterpretation of the true autonomic nervous regulation. We recommend that the respiratory pattern of participants should be evaluated before spectral HRV analysis to correctly understand changes in autonomic nervous regulation.

  14. Anxiety sensitivity moderates prognostic importance of rhythm-control versus rate-control strategies in patients with atrial fibrillation and congestive heart failure: insights from the Atrial Fibrillation and Congestive Heart Failure Trial.

    PubMed

    Frasure-Smith, Nancy; Lespérance, François; Talajic, Mario; Khairy, Paul; Dorian, Paul; O'Meara, Eileen; Roy, Denis

    2012-05-01

    Patients with high anxiety sensitivity (AS) become extremely anxious with heart rate increases, palpitations, and symptoms of psychological arousal. AS predicts panic attacks. In atrial fibrillation (AF), AS correlates with symptom preoccupation and reduced quality of life. We assessed whether AS is associated with outcomes of rhythm-control versus rate-control in congestive heart failure (CHF) patients with AF. Before random assignment, 933 participants (172 women) in the Atrial Fibrillation and Congestive Heart Failure Trial completed the Anxiety Sensitivity Inventory (ASI). Cox proportional hazards models showed no main effects of treatment (P=0.61) or AS (P=0.72) for time to cardiovascular death, but these factors interacted significantly (P=0.020). High AS patients (upper quartile, ASI ≥33) randomly assigned to rhythm-control had significantly lower cardiovascular mortality than those receiving rate-control (hazard ratio, 0.54; 95% confidence interval, 0.32-0.93; P=0.022). With lower ASI scores (<33), treatments did not differ (hazard ratio, 1.12; 95% confidence interval, 0.83-1.51; P=0.46). The interaction between treatment and dichotomized ASI scores remained significant (P=0.009) after adjustment for covariates including age, sex, hypertension, diabetes, creatinine, ejection fraction, time since first diagnosis of AF, New York Heart Association functional class, depression symptoms, marital status, and baseline β-blockers, angiotensin-converting enzyme inhibitors, oral anticoagulants, and implantable cardioverter-defibrillators. Atrial fibrillation and congestive heart failure patients with high AS had better long-term prognosis with rhythm- than rate-control. If replicated, AS should be considered in treatment selection. Research is also needed concerning mechanisms and possible joint AS-AF treatments. URL: http://www.clinicaltrials.gov. Unique identifier: NCT88597077.

  15. What does self-rated health mean? Changes and variations in the association of obesity with objective and subjective components of self-rated health*

    PubMed Central

    Altman, Claire E.; Van Hook, Jennifer; Hillemeier, Marianne

    2016-01-01

    There are concerns about the meaning of SRH and the factors individuals consider. To illustrate how SRH is contextualized, we examine how the obesity-SRH association varies across age, periods, and cohorts. We decompose SRH into subjective and objective components and used a mechanism-based APC model approach with four decades (1970s-2000s) and five birth cohorts of NHANES data (N=26,184). Obese adults rate their health more negatively than non-obese when using overall SRH with little variation by age, period, or cohort. However, when we decomposed SRH into objective and subjective components, the obesity gap widened with increasing age in objective SRH, but narrowed in subjective SRH. Additionally, the gap narrowed for more recently-born cohorts for objective SRH, but widened for subjective SRH. The results provide indirect evidence that the relationship between obesity and SRH is socially patterned according to exposure to information about obesity and the availability of resources to manage it. PMID:26811364

  16. Compilation of Failure Data and Fault Tree Analysis for Geothermal Energy Conversion Systems

    SciTech Connect

    Miller, F.L., Jr.; Zimmerman, D.E.

    1990-11-01

    The failure data for geothermal energy conversion facilities collected to date are compiled and tabled. These facilities have not accumulated sufficient production history to reliably estimated component failure rates. In addition, the improvements made in drilling technology in recent years may have made less pertinent the accumulation of data on well failures.

  17. Translating effects of inbreeding depression on component vital rates to overall population growth in endangered bighorn sheep.

    PubMed

    Johnson, Heather E; Mills, L Scott; Wehausen, John