Science.gov

Sample records for component failure rates

  1. 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.

  2. 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.

  3. 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.

  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. The Hanford Site generic component failure-rate database compared with other generic failure-rate databases

    SciTech Connect

    Reardon, M.F.; Zentner, M.D.

    1992-11-01

    The Risk Assessment Technology Group, Westinghouse Hanford Company (WHC), has compiled a component failure rate database to be used during risk and reliability analysis of nonreactor facilities. Because site-specific data for the Hanford Site are generally not kept or not compiled in a usable form, the database was assembled using information from a variety of other established sources. Generally, the most conservative failure rates were chosen from the databases reviewed. The Hanford Site database has since been used extensively in fault tree modeling of many Hanford Site facilities and systems. The purpose of this study was to evaluate the reasonableness of the data chosen for the Hanford Site database by comparing the values chosen with the values from the other databases.

  6. 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.

  7. 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.

  8. Component failure-rate data with potential applicability to a nuclear fuel reprocessing plant

    SciTech Connect

    Dexter, A.H.; Perkins, W.C.

    1982-07-01

    Approximately 1223 pieces of component failure-rate data, under 136 subject categories, have been compiled from published literature and computer searches of a number of data bases. Component selections were based on potential applicability to facilities for reprocessing spent nuclear fuels. The data will be useful in quantifying fault trees for probabilistic safety analyses and risk assessments.

  9. 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.

  10. 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.

  11. A novel approach for analyzing fuzzy system reliability using different types of intuitionistic fuzzy failure rates of components.

    PubMed

    Kumar, Mohit; Yadav, Shiv Prasad

    2012-03-01

    This paper addresses the fuzzy system reliability analysis using different types of intuitionistic fuzzy numbers. Till now, in the literature, to analyze the fuzzy system reliability, it is assumed that the failure rates of all components of a system follow the same type of fuzzy set or intuitionistic fuzzy set. However, in practical problems, such type of situation rarely occurs. Therefore, in the present paper, a new algorithm has been introduced to construct the membership function and non-membership function of fuzzy reliability of a system having components following different types of intuitionistic fuzzy failure rates. Functions of intuitionistic fuzzy numbers are calculated to construct the membership function and non-membership function of fuzzy reliability via non-linear programming techniques. Using the proposed algorithm, membership functions and non-membership functions of fuzzy reliability of a series system and a parallel systems are constructed. Our study generalizes the various works of the literature. Numerical examples are given to illustrate the proposed algorithm.

  12. 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.

  13. 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.

  14. 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.

  15. Failure rate analysis using GLIMMIX

    SciTech Connect

    Moore, L.M.; Hemphill, G.M.; Martz, H.F.

    1998-12-01

    This paper illustrates use of a recently developed SAS macro, GLIMMIX, for implementing an analysis suggested by Wolfinger and O`Connell (1993) in modeling failure count data with random as well as fixed factor effects. Interest in this software tool arose from consideration of modernizing the Failure Rate Analysis Code (FRAC), developed at Los Alamos National Laboratory in the early 1980`s by Martz, Beckman and McInteer (1982). FRAC is a FORTRAN program developed to analyze Poisson distributed failure count data as a log-linear model, possibly with random as well as fixed effects. These statistical modeling assumptions are a special case of generalized linear mixed models, identified as GLMM in the current statistics literature. In the nearly 15 years since FRAC was developed, there have been considerable advances in computing capability, statistical methodology and available statistical software tools allowing worthwhile consideration of the tasks of modernizing FRAC. In this paper, the approaches to GLMM estimation implemented in GLIMMIX and in FRAC are described and a comparison of results for the two approaches is made with data on catastrophic time-dependent pump failures from a report by Martz and Whiteman (1984). Additionally, statistical and graphical model diagnostics are suggested and illustrated with the GLIMMIX analysis results.

  16. 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 .

  17. 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.

  18. Failure rate data for fusion safety and risk assessment

    SciTech Connect

    Cadwallader, L.C.

    1993-01-01

    The Fusion Safety Program (FSP) at the Idaho National Engineering Laboratory (INEL) conducts safety research in materials, chemical reactions, safety analysis, risk assessment, and in component research and development to support existing magnetic fusion experiments and also to promote safety in the design of future experiments. One of the areas of safety research is applying probabilistic risk assessment (PRA) methods to fusion experiments. To apply PRA, we need a fusion-relevant radiological dose code and a component failure rate data base. This paper describes the FSP effort to develop a failure rate data base for fusion-specific components.

  19. Failure rate data for fusion safety and risk assessment

    SciTech Connect

    Cadwallader, L.C.

    1993-04-01

    The Fusion Safety Program (FSP) at the Idaho National Engineering Laboratory (INEL) conducts safety research in materials, chemical reactions, safety analysis, risk assessment, and in component research and development to support existing magnetic fusion experiments and also to promote safety in the design of future experiments. One of the areas of safety research is applying probabilistic risk assessment (PRA) methods to fusion experiments. To apply PRA, we need a fusion-relevant radiological dose code and a component failure rate data base. This paper describes the FSP effort to develop a failure rate data base for fusion-specific components.

  20. 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.

  1. Code System for the Analysis of Component Failure Data with a Compound Statistical Model.

    2000-08-22

    Version 00 Two separate but similar Fortran computer codes have been developed for the analysis of component failure data with a compound statistical model: SAFE-D and SAFE-R. The SAFE-D code (Statistical Analysis for Failure Estimation-failure-on-Demand) analyzes data which give the observed number of failures (failure to respond properly) in a specified number of demands for several similar components that should change their condition upon demand. The second program, SAFE-R (Statistical Analysis for Failure Estimation-failure Rate)more » is to be used to analyze normally operating components for which the observed number of failures in a specified operating time is given. In both these codes the failure parameter (failure probability per demand for SAFE-D or failure rate for SAFE-R) may be assumed equal for all similar components (the homogeneous failure model) or may be assumed to be a random variable distributed among similar components according to a prior distribution (the heterogeneous or compound failure model). Related information can be found at the developer's web site: http://www.mne.ksu.edu/~jks/.« less

  2. 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.

  3. Sterilization: new method options, failure rate info.

    PubMed

    1998-01-01

    This article discusses new sterilization methods for tubal ligation, failure rates, and risks for ectopic pregnancy in the US. The Filshie clip, which was developed by Femcare, Ltd. in Nottingham, England, and is distributed by Avalon Medical Corp of Vermont, was approved by the US Food and Drug Administration in September 1996. The company has provided training sessions at major universities nationwide and exhibited at national professional association meetings. A training video and two more films will be available in 1998. The new clip is considered a more modern approach to a tubal occlusion method, which relies on newer materials and solves prior problems. Physicians usually used Falope rings, which had better failure rates than the Hulka clip and bipolar coagulation methods. There is a need for more long-term and large scale information exchange about the new Filshie clip. Some physicians still use the Falope ring because it is cost effective and well-studied. Physicians are warned to continue to advise women about the potential failure rates up to 10 years after sterilization and the 1 in 3 risk of ectopic pregnancy. Counseling about failure rates and the risk of ectopic pregnancy should target women under 30 years old, who have the highest failure rates, and women 30-34 years old. All sterilized women should be advised to seek a provider immediately if they have pregnancy symptoms following sterilization. Counseling should include the issue of "regrets," since it is a permanent method. All women should know about nonpermanent methods and experience a basic informed consent process. Young women and newly divorced women are particularly vulnerable to the "regrets" syndrome.

  4. 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.

  5. 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

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

    PubMed

    Daner Iii, William E; 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

  7. 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.

  8. Mechanism of failure of two pyrotechnic components

    SciTech Connect

    Munger, A.C.; Woods, C.M.

    1985-01-01

    An investigation of two unrelated pyrotechnic test device misfires revealed an ignition phenomenon that helps to explain the well-known necessity of maintaining good integrity between bridgewire and powder in hot-wire devices that use insensitive pyrotechnic powders. The factor common to both devices was the TiH/sub 1.65/:KC10/sub 4/ in a 33:67 weight percent ratio. This material is being used because of its high static insensitivity, a characteristic that makes good bridgewire contact mandatory for reliable ignition. Extensive work with a scanning electron microscope revealed that not only does the bridgewire require entrapment, but the initiation reaction gases must be contained within the immediate vicinity of the bridgewire or the initiation will not be sustained. Evidence is presented to document the phenomenon that caused the misfire of both components that were investigated. 9 refs., 17 figs.

  9. 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.

  10. Analysis of electronic component failures using high-density radiography

    SciTech Connect

    Tuohig, W.D.; Potter, T.J.

    1991-11-01

    The exceptional resolution and nondestructive nature of microfocus radiography has proven to be extremely useful in the diagnosis of electronic component failures, particularly when the components are contained in sealed or encapsulated assemblies. An epoxy-encapsulated NTC thermistor and an epitaxial silicon P-N junction photodetector are examples of discrete devices in which the cause of failure was correctly hypothesized directly from a radiographic image. Subsequent destructive physical examinations confirmed the initial hypothesis and established the underlying cause in each case. The problem in a vacuum switch tube which failed to function was apparent in the radiographic image, but the underlying cause was not clear. However, radiography also showed that the position of a flat cable in the assembly could contribute to failure, an observation which resulted in a change in manufacturing procedure. In each of these instances, microradiography played a key role in decisions concerning the root cause of failure, product viability, and corrective action. 15 refs., 10 figs.

  11. 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.

  12. 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

  13. Detection of Component Failures for Smart Structure Control Systems

    NASA Astrophysics Data System (ADS)

    Okubo, Hiroshi

    Uncertainties in the dynamics model of a smart structure are often of significance due to model errors caused by parameter identification errors and reduced-order modeling of the system. Design of a model-based Failure Detection and Isolation (FDI) system for smart structures, therefore, needs careful consideration regarding robustness with respect to such model uncertainties. In this paper, we proposes a new method of robust fault detection that is insensitive to the disturbances caused by unknown modeling errors while it is highly sensitive to the component failures. The capability of the robust detection algorithm is examined for the sensor failure of a flexible smart beam control system. It is shown by numerical simulations that the proposed method suppresses the disturbances due to model errors and markedly improves the detection performance.

  14. Product component genealogy modeling and field-failure prediction

    DOE PAGESBeta

    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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Increased heteroscedasticity of heart rate in fatal heart failure

    NASA Astrophysics Data System (ADS)

    Struzik, Z. R.; Kiyono, K.; Hayano, J.; Watanabe, E.; Yamamoto, Y.

    2008-04-01

    Healthy human heart rate is known to fluctuate in a highly complex manner, displaying complexity characteristics such as those shared by physical systems at a critical state. It is, however, widely believed that chronic heart failure reduces this complexity and that heart rate data from chronic-heart-failure patients can be used for the validation of complexity measures and paradigms applicable both to heart rate and more generally to assess any system's complexity. Here, we counter the above belief, showing an increase in fluctuations and in complexity of heart rate in chronic-heart-failure patients, in particular those at risk of death. This is supported by evidence of increased non-Gaussianity and heteroscedasticity resulting from the emergence of a characteristic correlation scale in the magnitude correlation landscape.

  20. 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

  1. Failures of CMOS Circuits Irradiated At Low Rates

    NASA Technical Reports Server (NTRS)

    Goben, Charles A.; Price, William E.

    1990-01-01

    Report describes experiments on irradiation of SGS 4007 complementary metal oxide/semiconductor (CMOS) integrated inverter circuits by 60Co and 137Cs radioactive sources. Purpose of experiments to supplement previous observations that minimum radiation doses at which failure occurred in more-complicated CMOS parts were lower at lower dose rates.

  2. 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.

  3. 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.

  4. 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...

  5. 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...

  6. Rate and time dependent failure of structural adhesives

    NASA Technical Reports Server (NTRS)

    Brinson, H. F.; Renieri, M. P.; Herakovich, C. T.

    1975-01-01

    Studies on two adhesives (Metlbond 1113 and 1113-2) identified as having important applications in the bonding of composite materials are presented. A testing program to ascertain stress-strain, strain-rate, time, yield, and/or failure behavior of these materials in bulk form using uniaxial tensile constant strain-rate, creep, and relaxation tests is described. The stress-strain behavior of each material is shown to be significantly rate dependent. A rate dependent stress whitening (crazing) phenomenon occurs prior to either yield or fracture. A region of linear elasticity, a region of viscoelasticity, and the onset of yielding are identified in the stress-strain behavior. The linear elastic limit and the yield point are shown to be rate dependent and agree well with an empirical equation proposed by Ludwik. A creep to failure phenomenon is shown to exist and is correlated with a delayed yield equation proposed by Crochet. Analytical predictions based on a modified Bingham model are shown to agree well with experimental stress-strain strain-rate data. Analytical predictions based on a modified Ramberg-Osgood equation are also shown for comparison purposes.

  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. PMID:11878225

  8. 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.

  9. Heart rate reduction in coronary artery disease and heart failure.

    PubMed

    Ferrari, Roberto; Fox, Kim

    2016-08-01

    Elevated heart rate is known to induce myocardial ischaemia in patients with coronary artery disease (CAD), and heart rate reduction is a recognized strategy to prevent ischaemic episodes. In addition, clinical evidence shows that slowing the heart rate reduces the symptoms of angina by improving microcirculation and coronary flow. Elevated heart rate is an established risk factor for cardiovascular events in patients with CAD and in those with chronic heart failure (HF). Accordingly, reducing heart rate improves prognosis in patients with HF, as demonstrated in SHIFT. By contrast, data from SIGNIFY indicate that heart rate is not a modifiable risk factor in patients with CAD who do not also have HF. Heart rate is also an important determinant of cardiac arrhythmias; low heart rate can be associated with atrial fibrillation, and high heart rate after exercise can be associated with sudden cardiac death. In this Review, we critically assess these clinical findings, and propose hypotheses for the variable effect of heart rate reduction in cardiovascular disease.

  10. 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.

  11. 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. 159.67 Section 159.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must...

  12. 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. 159.67 Section 159.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must...

  13. 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. 159.67 Section 159.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.67 Electrical component ratings. Electrical components must...

  14. 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

  15. 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.

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. Failure of Orthodontic Mini-implants by Patient Age, Sex, and Arch; Number of Primary Insertions; and Frequency of Reinsertions After Failure: An Analysis of the Implant Failure Rate and Patient Failure Rate.

    PubMed

    Kim, Jong-Wan; Lee, Nam-Ki; Sim, Hye-Young; Yun, Pil-Young; Lee, Jong-Ho

    2016-01-01

    This study aimed to analyze and compare the failure rate of orthodontic mini-implants (OMIs) in terms of the number of implants (implant failure rate [IFR]) and patients (patient failure rate [PFR]) according to the age, sex, and arch of the patients, the number of primary insertions, and frequency of reinsertions after failure. A total of 394 OMIs (1.2 mm in diameter; 7.0 mm in length) were inserted in 125 patients (24 male and 101 female, mean age 21.95 ± 7.60 years). IFR and PFR were evaluated according to the age and sex of the patient, the number of primary insertions, and the frequency of reinsertions after failure. PFR was 40.08% and IFR was 18.27% after the first insertions. PFR was higher than IFR regardless of the number of OMIs inserted. IFR increased with an increase in the frequency of reinsertions, reaching 66.67% after the fourth insertion, whereas PFR decreased to 25.00% after the second insertion and to 66.67% after the third and fourth insertions. The overall PFR and IFR were 40.80% and 19.29%, respectively. Although male patients, young patients, and location in the mandible showed higher PFR and IFR, there were no significant differences between PFR and IFR according to the sex, age, or arch. PFR was higher than IFR in this study, indicating that the treatment process could be more strongly affected by PFR than IFR. The failure rate can increase with the frequency of OMI reinsertions after failure. Sex, age, and arch may have no correlation with primary or recurrent OMI failure. PMID:27333014

  5. Failure of Orthodontic Mini-implants by Patient Age, Sex, and Arch; Number of Primary Insertions; and Frequency of Reinsertions After Failure: An Analysis of the Implant Failure Rate and Patient Failure Rate.

    PubMed

    Kim, Jong-Wan; Lee, Nam-Ki; Sim, Hye-Young; Yun, Pil-Young; Lee, Jong-Ho

    2016-01-01

    This study aimed to analyze and compare the failure rate of orthodontic mini-implants (OMIs) in terms of the number of implants (implant failure rate [IFR]) and patients (patient failure rate [PFR]) according to the age, sex, and arch of the patients, the number of primary insertions, and frequency of reinsertions after failure. A total of 394 OMIs (1.2 mm in diameter; 7.0 mm in length) were inserted in 125 patients (24 male and 101 female, mean age 21.95 ± 7.60 years). IFR and PFR were evaluated according to the age and sex of the patient, the number of primary insertions, and the frequency of reinsertions after failure. PFR was 40.08% and IFR was 18.27% after the first insertions. PFR was higher than IFR regardless of the number of OMIs inserted. IFR increased with an increase in the frequency of reinsertions, reaching 66.67% after the fourth insertion, whereas PFR decreased to 25.00% after the second insertion and to 66.67% after the third and fourth insertions. The overall PFR and IFR were 40.80% and 19.29%, respectively. Although male patients, young patients, and location in the mandible showed higher PFR and IFR, there were no significant differences between PFR and IFR according to the sex, age, or arch. PFR was higher than IFR in this study, indicating that the treatment process could be more strongly affected by PFR than IFR. The failure rate can increase with the frequency of OMI reinsertions after failure. Sex, age, and arch may have no correlation with primary or recurrent OMI failure.

  6. 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.

  7. Coupling failure between stem and femoral component in a constrained revision total knee arthroplasty.

    PubMed

    Butt, Ahsan Javed; Shaikh, Aamir Hassan; Cameron, Hugh U

    2013-02-01

    Knee revision using constrained implants is associated with greater stresses on the implant and interface surfaces. The present report describes a case of failure of the screw coupling between the stem and the femoral component. The cause of the failure is surmised with outline of the treatment in this case with extensive femoral bone loss. Revision implant stability was augmented with the use of a cemented femoral stem, screw fixation and the metaphyseal sleeve of an S-ROM modular hip system (DePuy international Ltd).

  8. 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.

  9. Dynamic heart rate estimation using principal component analysis.

    PubMed

    Yu, Yong-Poh; Raveendran, P; Lim, Chern-Loon; Kwan, Ban-Hoe

    2015-11-01

    In this paper, facial images from various video sequences are used to obtain a heart rate reading. In this study, a video camera is used to capture the facial images of eight subjects whose heart rates vary dynamically, between 81 and 153 BPM. Principal component analysis (PCA) is used to recover the blood volume pulses (BVP) which can be used for the heart rate estimation. An important consideration for accuracy of the dynamic heart rate estimation is to determine the shortest video duration that realizes it. This video duration is chosen when the six principal components (PC) are least correlated amongst them. When this is achieved, the first PC is used to obtain the heart rate. The results obtained from the proposed method are compared to the readings obtained from the Polar heart rate monitor. Experimental results show the proposed method is able to estimate the dynamic heart rate readings using less computational requirements when compared to the existing method. The mean absolute error and the standard deviation of the absolute errors between experimental readings and actual readings are 2.18 BPM and 1.71 BPM respectively.

  10. Dynamic heart rate estimation using principal component analysis

    PubMed Central

    Yu, Yong-Poh; Raveendran, P.; Lim, Chern-Loon; Kwan, Ban-Hoe

    2015-01-01

    In this paper, facial images from various video sequences are used to obtain a heart rate reading. In this study, a video camera is used to capture the facial images of eight subjects whose heart rates vary dynamically, between 81 and 153 BPM. Principal component analysis (PCA) is used to recover the blood volume pulses (BVP) which can be used for the heart rate estimation. An important consideration for accuracy of the dynamic heart rate estimation is to determine the shortest video duration that realizes it. This video duration is chosen when the six principal components (PC) are least correlated amongst them. When this is achieved, the first PC is used to obtain the heart rate. The results obtained from the proposed method are compared to the readings obtained from the Polar heart rate monitor. Experimental results show the proposed method is able to estimate the dynamic heart rate readings using less computational requirements when compared to the existing method. The mean absolute error and the standard deviation of the absolute errors between experimental readings and actual readings are 2.18 BPM and 1.71 BPM respectively. PMID:26601022

  11. 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…

  12. 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

  13. Vibration detection of component operability. [for Space Shuttle Orbiter failure prevention

    NASA Technical Reports Server (NTRS)

    Baird, B.

    1976-01-01

    In order to prevent catastrophic failure and eliminate unnecessary periodic maintenance in the Space Shuttle Orbiter dynamic components, instrumentation for detecting incipient failure in these components is required. This study investigated the utilization of vibrational phenomena as one of the principal physical parameters on which to base the design of this instrumentation. Baseline vibration data was collected from three aircraft type fans and two aircraft type pumps over a frequency range from a few Hertz to greater than 300 kHz. The baseline data included spectrum analysis of the vibration and detected carrier signals, as well as several non-spectrum parameters. Several defects were introduced into the five test items, and all defects were detected by at least one of the parameters with a margin of at least 2:1 over the worst case baseline.

  14. 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.

  15. 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.

  16. 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.

  17. Effect of loading rate on tensile properties and failure behavior of glass fibre/epoxy composite

    NASA Astrophysics Data System (ADS)

    Mahato, K. K.; Biswal, M.; Rathore, D. K.; Prusty, R. K.; Dutta, K.; Ray, B. C.

    2016-02-01

    Fibre reinforced polymeric (FRP) composite materials are subjected to different range of loading rates during their service life. Present investigation is focused on to study the effects of variation of loading rates on mechanical behavior and various dominating failure modes of these potential materials when subjected to tensile loading. The results revealed that on the variation of loading rates the ultimate tensile strength varies but the tensile modulus is mostly unaffected. Furthermore, the strain to failure is also increasing with increase in loading rates. Different failure patterns of glass/epoxy composite tested at 1, 10,100, 500 and 1000 mm/min loading rates are identified. Scanning electron micrographs shows various dominating failures modes in the glass/epoxy composite.

  18. Constrained independent component analysis approach to nonobtrusive pulse rate measurements

    NASA Astrophysics Data System (ADS)

    Tsouri, Gill R.; Kyal, Survi; Dianat, Sohail; Mestha, Lalit K.

    2012-07-01

    Nonobtrusive pulse rate measurement using a webcam is considered. We demonstrate how state-of-the-art algorithms based on independent component analysis suffer from a sorting problem which hinders their performance, and propose a novel algorithm based on constrained independent component analysis to improve performance. We present how the proposed algorithm extracts a photoplethysmography signal and resolves the sorting problem. In addition, we perform a comparative study between the proposed algorithm and state-of-the-art algorithms over 45 video streams using a finger probe oxymeter for reference measurements. The proposed algorithm provides improved accuracy: the root mean square error is decreased from 20.6 and 9.5 beats per minute (bpm) for existing algorithms to 3.5 bpm for the proposed algorithm. An error of 3.5 bpm is within the inaccuracy expected from the reference measurements. This implies that the proposed algorithm provided performance of equal accuracy to the finger probe oximeter.

  19. 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.

  20. 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.

  1. 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.

  2. Delays and Growth Rates of Multiple TEOAE Components

    NASA Astrophysics Data System (ADS)

    Goodman, Shawn S.; Mertes, Ian B.; Scheperle, Rachel A.

    2011-11-01

    Bandpass-filtered transient-evoked otoacoustic emissions (TEOAEs) show multiple energy peaks with time delays that are invariant with level and growth rates that vary with delay and stimulus level, suggesting that multiple generation mechanisms may be involved at moderate and high stimulus levels. We measured delays and magnitude growths of multiple TEOAE energy peaks and compared the results obtained from linear and nonlinear extraction methods. To test the hypothesis that early components are generated at the basal portion of the cochlea, delays and growth rates were also measured in the presence of highpass masking noise for a subset of subjects. No effect of the highpass masking was seen. The results are discussed in terms of potential generation mechanisms of the multiple energy peaks.

  3. Fatigue among caregivers of chronic renal failure patients: a principal components analysis.

    PubMed

    Schneider, Robert A

    2003-12-01

    Quality of life for caregivers of ESRD patients has not been well addressed. The physical and psychological status of this overlooked group can be important in the recovery or adaptation of patients with chronic renal failure. One particular symptom of a reduced quality of life of such caregivers is that of fatigue. The study tested the reliability of both existing and newer fatigue measures. Measures with high reliability yielded a single construct of fatigue in a principal components analysis in this study of 99 caregivers. Implications for practice are addressed. Potential for further study is recommended. PMID:14730783

  4. 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.

  5. FAILPROB--A Computer Program to Compute the Probability of Failure of a Brittle Component

    SciTech Connect

    WELLMAN, GERALD W.

    2002-02-01

    FAILPROB is a computer program that applies the Weibull statistics characteristic of brittle failure of a material along with the stress field resulting from a finite element analysis to determine the probability of failure of a component. FAILPROB uses the statistical techniques for fast fracture prediction (but not the coding) from the N.A.S.A. - CARES/life ceramic reliability package. FAILPROB provides the analyst at Sandia with a more convenient tool than CARES/life because it is designed to behave in the tradition of structural analysis post-processing software such as ALGEBRA, in which the standard finite element database format EXODUS II is both read and written. This maintains compatibility with the entire SEACAS suite of post-processing software. A new technique to deal with the high local stresses computed for structures with singularities such as glass-to-metal seals and ceramic-to-metal braze joints is proposed and implemented. This technique provides failure probability computation that is insensitive to the finite element mesh employed in the underlying stress analysis. Included in this report are a brief discussion of the computational algorithms employed, user instructions, and example problems that both demonstrate the operation of FAILPROB and provide a starting point for verification and validation.

  6. Transfer component skill deficit rates among Veterans who use wheelchairs.

    PubMed

    Koontz, Alicia M; Tsai, Chung-Ying; Hogaboom, Nathan S; Boninger, Michael L

    2016-01-01

    The purpose of this study was to quantify the deficit rates for transfer component skills in a Veteran cohort and explore the relationship between deficit rates and subject characteristics. Seventy-four men and 18 women performed up to four transfers independently from their wheelchair to a mat table while a therapist evaluated their transfer techniques using the Transfer Assessment Instrument. The highest deficit rates concerned the improper use of handgrips (63%). Other common problems included not setting the wheelchair up at the proper angle (50%) and not removing the armrest (58%). Veterans over 60 yr old and Veterans with moderate shoulder pain were more likely to set up their wheelchairs inappropriately than younger Veterans (p = 0.003) and Veterans with mild shoulder pain (p = 0.004). Women were less likely to remove their armrests than men (p = 0.03). Subjects with disabilities other than spinal cord injury were less inclined to set themselves up for a safe and easy transfer than the subjects with spinal cord injury (p ≤ 0.001). The results provide insight into the disparities present in transfer skills among Veterans and will inform the development of future transfer training programs both within and outside of the Department of Veterans Affairs. PMID:27149389

  7. 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

  8. Monitoring volcano precursory activity with the materials failure approach, using rates of cumulative seismic coda length

    SciTech Connect

    Cornelius, R.R.; Voight, B. . Dept. of Geosciences)

    1992-01-01

    The proportionality between the energy, E, of an elastic wave and the square of its amplitude led to the usage of Benioff diagrams'' for purposes of volcano monitoring. These diagrams show the time-integrated amplitude as [radical]E versus time. The authors propose to use accelerating cumulative coda length directly in volcano monitoring. This surrogate measure of energy'' is used for practical reasons, as it eliminates the intermediate step required for energy calculations with regional and instrument-specific constants. Rates of cumulative coda (s/day) may be used for the materials failure approach'' to eruption prediction, which fits data according to an empirical rate-acceleration relationship. The method allows numerical or graphical rate extrapolation towards the expected failure rate; eruption windows may be established. Rate series derived from either cumulative amplitude, cumulative coda, or calculated [radical]E can be analyzed by the materials failure approach equally well; neither series is favored by this method because of similar characteristics. They suggest rate interpolation from the time-integrated data over constant coda-increments instead of over constant time-increments. This results in an increasingly higher frequency of rate data towards the end of an accelerating time series. The end-weighted rate calculation emphasizes the latest precursory developments while it smooths noise at lower rates. Adjusting the applied constant coda-increment for rate calculations as a function of total encountered coda, is a technique for an automated and sequential update of the extrapolated failure time.

  9. 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.

  10. 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.

  11. 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.

  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. 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. PMID:18568354

  16. Be wary of methodology and biases in reading contraceptive failure rates.

    PubMed

    1986-08-01

    Dr. T. James Trussell of the Princeton University Office of Population Research maintains that both statistical methodology and built-in study bias can profoundly influence the contraceptive failure rates quoted in journal articles and patient package inserts. He believes that the Pearl index, 1 of the 2 currently popular methodologies, should be abandoned, indicating that a number of biases are "built into" the Pearl index. Consequently, it is difficult to interpret, and its results can vary, depending on the length of the study involved. Trussell advised clinicians to remember that "Pearl index figures are not equal to the percentage of women who will become pregnant in the 1st year of use." Instead of comparing against a standard of 100, as a percentage ranking does, the Pearl index divides the number of pregnancies by the number of women-months and multiplies that figure by 2000. Another limitation of the Pearl index is that investigators who want to push a specific contraceptive method can, consciously or not, interpret the index figures to support their position. Because woman-months make up the denominator of the equation, and it is "universally true that future rates decrease over time," the longer a study runs, says Trussell, the lower the contraceptive failure rate becomes. Trussell fa ors the life-table method of calculation for its "unambiguous interpretation" and its added use in calculating continuation rates. Yet, he warns that with any calculation method, sources of bias can still pose formidable problems in achieving accurate results. He suggests clinicians look for "the big five" when interpreting failure rate data: He suggests clinicians look for "the big five" when interpreting failure rate data: sample composition bias, especially in work comparing failure rates of 2 contraceptive methods; recall or response bias found in studies using survey or interview results; self-selection bias; misreporting; and poor model design. The original

  17. Atomic Scale Modeling of High Strain Rate Deformation and Failure of HCP Metals

    NASA Astrophysics Data System (ADS)

    Mackenchery, Karoon; Agarwal, Garvit; Dongare, Avinash

    2015-06-01

    A fundamental understanding of the microstructure effects on the defect evolution at the atomic resolution and the related contribution to plasticity at the macro-scales is needed to obtain a reliable performance of metallic materials in extreme environments. Large-scale molecular dynamics simulations are carried out to characterize the dynamic evolution of defect/damage structures during the deformation and failure behavior of HCP (Mg, Ti) metallic systems (single crystal and nanocrystalline at high strain rates as well as under shock loading conditions. The evolution of various types of dislocations, twins, faults, etc. and the related deformation and failure response (nucleation and growth of voids/cracks) will be discussed. The effects of strain rates on relationships between the microstructure and the strength of these materials at high strain rates and the underlying micromechanisms related to deformation and failure will be discussed.

  18. Effect of resistance exercise performed to volitional failure on ratings of perceived exertion.

    PubMed

    Vasquez, Ligia M; McBride, Jeffrey M; Paul, Judith A; Alley, Jessica R; Carson, Lauren T; Goodman, Courtney L

    2013-12-01

    The purpose of this investigation was to assess the effect of resistance exercise performed to volitional failure on ratings of perceived exertion (RPE) using power as an indication of fatigue. 12 male participants (M age = 21.9 yr., SD = 1.3) performed one set of back squats at three different intensities (50%, 70%, and 90% of one repetition maximum) for both a pre-determined number of repetitions (3) and to volitional failure. RPE was significantly different between sets at 50%, 70%, and 90% when performed to a pre-determined number of repetitions, but not during volitional failure. A decrease in power between the first and the last repetitions in the volitional failure sets suggests that fatigue may confound the relationship between RPE and intensity. PMID:24665804

  19. 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.

  20. 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.

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

    PubMed

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

    2015-01-01

    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

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

    PubMed

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

    2015-01-01

    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

  3. Application of Strain Non-Uniformity Index (SNI) Based Approach to Predict Failure in Sheet Metal Components

    NASA Astrophysics Data System (ADS)

    Date, P. P.; Jamadar, K. D.

    2016-08-01

    Industrial components are far too complex in shape and far too large in size compared to the laboratory scale test samples used to establish failure criteria like the forming limit diagram (FLD). These have been traditionally used to predict failure, but are found to often make wrong predictions due to their sensitivity to strain path, and forming conditions like temperature. The Strain Nonuniformity Index (SNI), a single parameter determined from the spatial strain distribution, may be used to predict failure and identify locations of failure or even imminent failure. This is possible regardless of temperature or even the method of forming (cold forming, hot forming, superplastic forming etc.). The paper presents a few results demonstrating successful applications of this novel SNI based technique.

  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. Optimal single-replacement for repairable products with different failure rate under a finite planning horizon

    NASA Astrophysics Data System (ADS)

    Chang, Wen Liang

    2015-04-01

    This paper provides a replacement policy for repairable products with free-repair warranty (FRW) under a finite planning horizon from the consumer's viewpoint. Assume that the product is replaced once within a finite planning horizon, and the failure rate of the second product is lower than the failure rate of the first product. Within FRW, the failed product is corrected by minimal repair without any cost to the consumers. After FRW, the failed product is repaired with a fixed repair cost to the consumers. However, each failure incurs a fixed downtime cost to the consumers over a finite planning horizon. In this paper, we derive the three models of the expected total disbursement cost within a finite planning horizon and some properties of the optimal replacement policy under some reasonable conditions are obtained. Finally, numerical examples are given to illustrate the features of the optimal replacement policy under various maintenance costs.

  6. Failure rate analysis of Goddard Space Flight Center spacecraft performance during orbital life

    NASA Technical Reports Server (NTRS)

    Norris, H. P.; Timmins, A. R.

    1976-01-01

    Space life performance data on 57 Goddard Space Flight Center spacecraft are analyzed from the standpoint of determining an appropriate reliability model and the associated reliability parameters. Data from published NASA reports, which cover the space performance of GSFC spacecraft launched in the 1960-1970 decade, form the basis of the analyses. The results of the analyses show that the time distribution of 449 malfunctions, of which 248 were classified as failures (not necessarily catastrophic), follow a reliability growth pattern that can be described with either the Duane model or a Weibull distribution. The advantages of both mathematical models are used in order to: identify space failure rates, observe chronological trends, and compare failure rates with those experienced during the prelaunch environmental tests of the flight model spacecraft.

  7. 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

  8. 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…

  9. Failure Pressure and Leak Rate of Steam Generator Tubes With Stress Corrosion Cracks

    SciTech Connect

    Majumdar, S.; Kasza, K.; Park, J.Y.; Bakhitiari, S.

    2002-07-01

    This paper illustrates the use of an 'equivalent rectangular crack' approach to predict leak rates through laboratory generated stress corrosion cracks. A comparison between predicted and observed test data on rupture and leak rate from laboratory generated stress corrosion cracks are provided. Specimen flaws were sized by post-test fractography in addition to pre-test advanced eddy current technique. The test failure pressures and leak rates are shown to be closer to those predicted on the basis of fractography than on NDE. However, the predictions based on NDE results are encouraging, particularly because they have the potential to determine a more detailed geometry of ligamentous cracks from which more accurate predictions of failure pressure and leak rate can be made in the future. (authors)

  10. 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.

  11. Continuous positive airway pressure increases heart rate variability in heart failure patients with obstructive sleep apnoea.

    PubMed

    Gilman, Matthew P; Floras, John S; Usui, Kengo; Kaneko, Yasuyuki; Leung, Richard S T; Bradley, T Douglas

    2008-02-01

    Patients with heart failure or OSA (obstructive sleep apnoea) have reduced HF-HRV (high-frequency heart rate variability), indicating reduced cardiac vagal modulation, a marker of poor prognosis. CPAP (continuous positive airway pressure) abolishes OSA in patients with heart failure, but effects on daytime HF-HRV have not been determined. We hypothesized that, in patients with heart failure, treatment of coexisting OSA by CPAP would increase morning HF-HRV. In 19 patients with heart failure (left ventricular ejection fraction <45%) and OSA (>/=20 apnoeas and hypopnoeas/h of sleep), HF-HRV was quantified before and 1 month after randomization to a control or CPAP-treated group. In the control group (n=7), there were no changes in HF-HRV over the 1 month study during wakefulness in the morning. In the CPAP-treated group (n=12) HF-HRV increased significantly during wakefulness in the morning [from 2.43+/-0.55 to 2.82+/-0.50 log(ms(2)/Hz); P=0.002] due to an increase in transfer function between changes in lung volume and changes in HF-HRV (92.37+/-96.03 to 219.07+/-177.14 ms/l; P=0.01). In conclusion, treatment of coexisting OSA by nocturnal CPAP in patients with heart failure increases HF-HRV during morning wakefulness, indicating improved vagal modulation of heart rate. This may contribute to improved prognosis.

  12. 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. PMID:27573836

  13. 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.

  14. 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

  15. Schizophrenia as Failure of Left Hemispheric Dominance for the Phonological Component of Language

    PubMed Central

    Angrilli, Alessandro; Spironelli, Chiara; Elbert, Thomas; Crow, Timothy J.; Marano, Gianfranco; Stegagno, Luciano

    2009-01-01

    Background T. J. Crow suggested that the genetic variance associated with the evolution in Homo sapiens of hemispheric dominance for language carries with it the hazard of the symptoms of schizophrenia. Individuals lacking the typical left hemisphere advantage for language, in particular for phonological components, would be at increased risk of the typical symptoms such as auditory hallucinations and delusions. Methodology/Principal Findings Twelve schizophrenic patients treated with low levels of neuroleptics and twelve matched healthy controls participated in an event-related potential experiment. Subjects matched word-pairs in three tasks: rhyming/phonological, semantic judgment and word recognition. Slow evoked potentials were recorded from 26 scalp electrodes, and a laterality index was computed for anterior and posterior regions during the inter stimulus interval. During phonological processing individuals with schizophrenia failed to achieve the left hemispheric dominance consistently observed in healthy controls. The effect involved anterior (fronto-temporal) brain regions and was specific for the Phonological task; group differences were small or absent when subjects processed the same stimulus material in a Semantic task or during Word Recognition, i.e. during tasks that typically activate more widespread areas in both hemispheres. Conclusions/Significance We show for the first time how the deficit of lateralization in the schizophrenic brain is specific for the phonological component of language. This loss of hemispheric dominance would explain typical symptoms, e.g. when an individual's own thoughts are perceived as an external intruding voice. The change can be interpreted as a consequence of “hemispheric indecision”, a failure to segregate phonological engrams in one hemisphere. PMID:19223971

  16. Decreasing Congestive Heart Failure Readmission Rates Within 30 Days at the Tampa VA.

    PubMed

    Messina, William

    2016-01-01

    High hospital readmission rates contribute to the problem of escalating costs and fragmented quality in the US health care system. This article describes the implementation of a home telehealth (HT) performance improvement project with subsequent cost-avoidance savings. The HT project was designed to potentiate communication between and among patients, clinicians, and administrative staff, in addition to reducing readmissions for patients with congestive heart failure at the James A. Haley Veterans Hospital in Tampa, Florida. Pre- and post-HT implementation comparisons were made of readmission rates, costs, and veteran satisfaction from the same 4-month periods in 2012 and 2013. The application of telehealth and phone care initiatives reduced the congestive heart failure hospital readmission rate by 5%, decreased costs, and improved veteran satisfaction with overall care experience.

  17. Failure of a helium-neon laser to affect components of wound healing in vitro.

    PubMed

    Colver, G B; Priestley, G C

    1989-08-01

    The red light of a helium-neon (He-Ne) laser has been reported to stimulate wound healing and cell growth. To investigate the nature of its influence on wound healing we have studied seven components of the healing process in vitro: human skin fibroblast, epithelial and endothelial cell proliferation, cellular migration from skin explants, collagen lattice contraction, collagen synthesis and glycosaminoglycans (GAG) secretion. We used a 5 mW He-Ne laser emitting a I mm diameter beam of wavelength 633 nm. Cellular proliferation was not affected by irradiation three times a day for 3 days. There was no effect on cellular migration or on the rate of collagen lattice contraction. The rate of collagen synthesis, measured as the incorporation of 3H-proline into collagenase-sensitive protein, was no greater than that of controls and GAG secretion did not increase in the irradiated group. We have not found any significant effects of He-Ne irradiation.

  18. 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.

  19. Cancer detection rates of different prostate biopsy regimens in patients with renal failure.

    PubMed

    Hoşcan, Mustafa Burak; Özorak, Alper; Oksay, Taylan; Perk, Hakkı; Armağan, Abdullah; Soyupek, Sedat; Serel, Tekin Ahmet; Koşar, Alim

    2014-07-01

    We aimed to evaluate the cancer detection rates of 6-, 10-, 12-core biopsy regimens and the optimal biopsy protocol for prostate cancer diagnosis in patients with renal failure. A total of 122 consecutive patients with renal failure underwent biopsy with age-specific prostate-specific antigen (PSA) levels up to 20 ng/mL. The 12-core biopsy technique (sextant biopsy + lateral base, lateral mid-zone, lateral apex, bilaterally) performed to all patients. Pathology results were examined separately for each sextant, 10-core that exclude parasagittal mid-zones from 12-cores (10a), 10-core that exclude apex zones from 12-cores (10b) and 12-core biopsy regimens. Of 122 patients, 37 (30.3%) were positive for prostate cancer. The cancer detection rates for sextant, 10a, 10b and 12 cores were 17.2%, 29%, 23.7% and 30.7%, respectively. Biopsy techniques of 10a, 10b and 12 cores increased the cancer detection rates by 40%, 27.5% and 43.2% among the sextant technique, respectively. Biopsy techniques of 10a and 12 cores increased the cancer detection rates by 17.1% and 21.6% among 10b biopsy technique, respectively. There were no statistical differences between 12 core and 10a core about cancer detection rate. Adding lateral cores to sextant biopsy improves the cancer detection rates. In our study, 12-core biopsy technique increases the cancer detection rate by 5.4% among 10a core but that was not statistically different. On the other hand, 12-core biopsy technique includes all biopsy regimens. We therefore suggest 12-core biopsy or minimum 10-core strategy incorporating six peripheral biopsies with elevated age- specific PSA levels up to 20 ng/mL in patients with renal failure. PMID:24797801

  20. Cancer detection rates of different prostate biopsy regimens in patients with renal failure.

    PubMed

    Hoşcan, Mustafa Burak; Özorak, Alper; Oksay, Taylan; Perk, Hakkı; Armağan, Abdullah; Soyupek, Sedat; Serel, Tekin Ahmet; Koşar, Alim

    2014-07-01

    We aimed to evaluate the cancer detection rates of 6-, 10-, 12-core biopsy regimens and the optimal biopsy protocol for prostate cancer diagnosis in patients with renal failure. A total of 122 consecutive patients with renal failure underwent biopsy with age-specific prostate-specific antigen (PSA) levels up to 20 ng/mL. The 12-core biopsy technique (sextant biopsy + lateral base, lateral mid-zone, lateral apex, bilaterally) performed to all patients. Pathology results were examined separately for each sextant, 10-core that exclude parasagittal mid-zones from 12-cores (10a), 10-core that exclude apex zones from 12-cores (10b) and 12-core biopsy regimens. Of 122 patients, 37 (30.3%) were positive for prostate cancer. The cancer detection rates for sextant, 10a, 10b and 12 cores were 17.2%, 29%, 23.7% and 30.7%, respectively. Biopsy techniques of 10a, 10b and 12 cores increased the cancer detection rates by 40%, 27.5% and 43.2% among the sextant technique, respectively. Biopsy techniques of 10a and 12 cores increased the cancer detection rates by 17.1% and 21.6% among 10b biopsy technique, respectively. There were no statistical differences between 12 core and 10a core about cancer detection rate. Adding lateral cores to sextant biopsy improves the cancer detection rates. In our study, 12-core biopsy technique increases the cancer detection rate by 5.4% among 10a core but that was not statistically different. On the other hand, 12-core biopsy technique includes all biopsy regimens. We therefore suggest 12-core biopsy or minimum 10-core strategy incorporating six peripheral biopsies with elevated age- specific PSA levels up to 20 ng/mL in patients with renal failure.

  1. 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.

  2. Catheterization during adrenal vein sampling for primary aldosteronism: failure to use (1-24) ACTH may increase apparent failure rate.

    PubMed

    Kline, Gregory A; So, Benny; Dias, Valerian C; Harvey, Adrian; Pasieka, Janice L

    2013-07-01

    "Successful" adrenal vein catheterization in primary aldosteronism (PA) is often defined by a ratio of >3:1 of cortisol in the adrenal vein vs the inferior vena cava. Non-use of corticotropin (ACTH) during sampling may increase the apparent failure rate of adrenal vein catheterization due to lower cortisol levels. A retrospective study was performed on all patients with confirmed unilateral PA between June 2005 and August 2011. Adrenal vein sampling (AVS) included simultaneous bilateral baseline samples with repeat sampling 15 minutes after intravenous infusion of 250 μg of Cortrosyn (ACTH-S). Successful catheter placement was judged as adrenal cortisol:IVC cortisol of >3:1, applied to both baseline and ACTH-S samples and lateralization of aldosteronism was judged as normalized aldosterone/cortisol (A/C) ratio >3 times the contralateral A/C ratio. In ACTH-S samples, 94% of right-sided catheterizations were biochemically successful with 100% success on the left. Among baseline samples, only 47% of right- and 44% of left-sided samples met the 3:1 cortisol criteria. However, 95% of apparent "failed" baseline cortisol sets still showed lateralization of A/C ratios that matched the ultimate pathology. Non-ACTH-stimulated samples may be incorrectly judged as failed catheter placement when a 3:1 ratio is used. ACTH-stimulated sampling is the preferred means to confirm catheterization during AVS.

  3. 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.

  4. 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.

  5. Stellar capture rates for s-process strong component elements.

    NASA Astrophysics Data System (ADS)

    Mutti, P.; Corvi, F.; Athanassopoulos, K.; Beer, H.; Krupchitsky, P.

    The strong component of the s-process is required for the synthesis of the heaviest s-process elements, namely the lead and the bismuth isotopes. The termination of the path occurs via a cyclic process in which nuclei heavier than bismuth decay via alpha emission to isotopes of lead. In this mass region the abundances are strongly influenced by the double magic 208Pb which, having the smallest cross section of all the heavy elements, acts as a bottle-neck in the s-process path. In the framework of a thorough investigation in the atomic mass region around the neutron magic nuclei, the 209Bi and 207Pb capture cross sections were measured with high resolution at the Geel electron linear accelerator. Capture areas were determined for neutron resonances in a wide energy range and the Maxwellian-averaged cross sections were derived as a function of stellar temperature.

  6. Rate of occurrence of failures based on a nonhomogeneous Poisson process: an ozone analyzer case study.

    PubMed

    de Moura Xavier, José Carlos; de Andrade Azevedo, Irany; de Sousa Junior, Wilson Cabral; Nishikawa, Augusto

    2013-02-01

    Atmospheric pollutant monitoring constitutes a primordial activity in public policies concerning air quality. In São Paulo State, Brazil, the São Paulo State Environment Company (CETESB) maintains an automatic network which continuously monitors CO, SO(2), NO(x), O(3), and particulate matter concentrations in the air. The monitoring process accuracy is a fundamental condition for the actions to be taken by CETESB. As one of the support systems, a preventive maintenance program for the different analyzers used is part of the data quality strategy. Knowledge of the behavior of analyzer failure times could help optimize the program. To achieve this goal, the failure times of an ozone analyzer-considered a repairable system-were modeled by means of the nonhomogeneous Poisson process. The rate of occurrence of failures (ROCOF) was estimated for the intervals 0-70,800 h and 0-88,320 h, in which six and seven failures were observed, respectively. The results showed that the ROCOF estimate is influenced by the choice of the observation period, t(0) = 70,800 h and t(7) = 88,320 h in the cases analyzed. Identification of preventive maintenance actions, mainly when parts replacement occurs in the last interval of observation, is highlighted, justifying the alteration in the behavior of the inter-arrival times. The performance of a follow-up on each analyzer is recommended in order to record the impact of the performed preventive maintenance program on the enhancement of its useful life.

  7. The Effect of Perioperative Ketorolac on the Clinical Failure Rate of Meniscal Repair

    PubMed Central

    Proffen, Benedikt L.; Nielson, Jason H.; Zurakowski, David; Micheli, Lyle J.; Curtis, Christine; Murray, Martha M.

    2014-01-01

    Background: There has been recent interest in the effect of nonsteroidal anti-inflammatory medications on musculoskeletal healing. No studies have yet addressed the effect of these medications on meniscal healing. Hypothesis: The administration of ketorolac in the perioperative period will result in higher rates of meniscal repair clinical failure. Study design: Cohort study; Level of evidence, 3. Methods: A total of 110 consecutive patients underwent meniscal repair at our institution between August 1998 and July 2001. Three patients were lost to follow-up, and the remaining 107 (mean age, 15.9 ± 4.4 years) had a minimum 5-year follow-up (mean follow-up, 5.5 years). Thirty-two patients (30%) received ketorolac perioperatively. The primary outcome measure was reoperation for continued symptoms of meniscal pathology. Asymptomatic patients were evaluated by the International Knee Documentation Committee (IKDC) Subjective Knee Form, Short Form–36 (SF-36) Health Survey, and Knee Outcome Osteoarthritis Score (KOOS). Results: Kaplan-Meier survivorship revealed no difference in reoperation rates with and without the administration of perioperative ketorolac (P = .95). There was an overall failure rate of 35% (37/107 patients), with a 34% failure rate in patients receiving ketorolac (11/32 patients). Multivariable Cox regression confirmed that age, duration of symptoms, meniscal tear type, fixation technique, concurrent anterior cruciate ligament repair, and ketorolac usage did not have an impact on the rate of failure (P > .05 for all; ketorolac use, P > .50). Female sex (P = .04) and medial location (P = .01) were predictive of an increased risk for reoperation. Conclusion: Failure of meniscal repair was not altered with the administration of perioperative ketorolac. Further work studying the effects of longer term anti-inflammatory use after meniscal repair is necessary before stating that this class of medications has no effect on meniscal healing. Clinical

  8. Eating rate and preference of different concentrate components for cattle.

    PubMed

    Spörndly, E; Asberg, T

    2006-06-01

    Different feeds or combination of feeds were studied in 11 short-term experiments with the objective to identify concentrates that were especially desirable for cattle. Eating rate of different feeds was studied in 6 experiments using 10 heifers in a Latin square design with 2 blocks of 5 animals, 5 treatments (feeds), and 5 periods (days). Preference as shown by feed choice was studied in 5 experiments with 12 heifers. Paired comparisons of 4 different feeds (1 through 4) in the 6 possible combinations of 1 and 2, 1 and 3, 1 and 4, 2 and 3, 2 and 4, and 3 and 4 were performed. A control feed of ground barley was included in all experiments. In the eating rate and preference experiments, a total of 25 and 16 feeds, respectively, were studied. The categories of feeds studied were basic feeds, such as cereals, soybean meal, and rapeseed products, and feed mixtures based on ground barley with sweet additives or additives based on fat products. Pelleted concentrate mixtures were also evaluated. From the results obtained, the following feeds were identified as being among the most preferred feeds: pelleted feeds, heat-treated rapeseed meal, barley with 10% rapeseed fatty acid, barley with 10% palm oil, and barley with 10% glycerol, whereas ground palm kernel expeller was undesirable. A clear preference for pellets over ground barley was demonstrated, but no difference in preference was observed for the 3 different pellets that were compared.

  9. Eating rate and preference of different concentrate components for cattle.

    PubMed

    Spörndly, E; Asberg, T

    2006-06-01

    Different feeds or combination of feeds were studied in 11 short-term experiments with the objective to identify concentrates that were especially desirable for cattle. Eating rate of different feeds was studied in 6 experiments using 10 heifers in a Latin square design with 2 blocks of 5 animals, 5 treatments (feeds), and 5 periods (days). Preference as shown by feed choice was studied in 5 experiments with 12 heifers. Paired comparisons of 4 different feeds (1 through 4) in the 6 possible combinations of 1 and 2, 1 and 3, 1 and 4, 2 and 3, 2 and 4, and 3 and 4 were performed. A control feed of ground barley was included in all experiments. In the eating rate and preference experiments, a total of 25 and 16 feeds, respectively, were studied. The categories of feeds studied were basic feeds, such as cereals, soybean meal, and rapeseed products, and feed mixtures based on ground barley with sweet additives or additives based on fat products. Pelleted concentrate mixtures were also evaluated. From the results obtained, the following feeds were identified as being among the most preferred feeds: pelleted feeds, heat-treated rapeseed meal, barley with 10% rapeseed fatty acid, barley with 10% palm oil, and barley with 10% glycerol, whereas ground palm kernel expeller was undesirable. A clear preference for pellets over ground barley was demonstrated, but no difference in preference was observed for the 3 different pellets that were compared. PMID:16702285

  10. An implicit algorithm for a rate-dependent ductile failure model

    NASA Astrophysics Data System (ADS)

    Zuo, Q. H.; Rice, Jeremy R.

    2008-10-01

    An implicit numerical algorithm has been developed for a rate-dependent model for damage and failure of ductile materials under high-rate dynamic loading [F. L. Addessio and J. N. Johnson, J. Appl. Phys. 74, 1640 (1993)]. Over each time step, the algorithm first implicitly determines the equilibrium state on a Gurson surface, and then calculates the final state by solving viscous relaxation equations, also implicitly. Numerical examples are given to demonstrate the key features of the algorithm. Compared to the explicit algorithm used previously, the current algorithm allows significantly larger time steps that can be used in the analysis. As the viscosity of the material vanishes, the results of the rate-dependent model are shown here to converge to that of the corresponding rate-independent model, a result not achieved with the explicit algorithm.

  11. 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.

  12. 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

  13. 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).

  14. 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.

  15. Optimal number of minimal repairs with cumulative repair cost limit for a two-unit system with failure rate interactions

    NASA Astrophysics Data System (ADS)

    Lai, Min-Tsai; Yan, Huey

    2016-01-01

    A discrete replacement model is presented that includes a cumulative repair cost limit for a two-unit system with failure rate interactions between the units. We assume a failure in unit 1 causes the failure rate in unit 2 to increase, whereas a failure in unit 2 causes a failure in unit 1, resulting in a total system failure. If unit 1 fails and the cumulative repair cost till to this failure is less than a limit L, then unit 1 is repaired. If there is a failure in unit 1 and the cumulative repair cost exceeds L or the number of failures equals n, the entire system is preventively replaced. The system is also replaced at a total failure, and such replacement cost is higher than the preventive replacement cost. The long-term expected cost per unit time is derived using the expected costs as the optimality criterion. The minimum-cost policy is derived, and existence and uniqueness are proved.

  16. 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. PMID:16252814

  17. Sleep Apnea in Heart Failure Increases Heart Rate Variability and Sympathetic Dominance

    PubMed Central

    Szollosi, Irene; Krum, Henry; Kaye, David; Naughton, Matthew T.

    2007-01-01

    Aims: Sleep disordered breathing (SDB) is common in heart failure and ventilation is known to influence heart rate. Our aims were to assess the influence of SDB on heart rate variability (HRV) and to determine whether central sleep apnea (CSA) and obstructive sleep apnea (OSA) produced different patterns of HRV. Methods and Results: Overnight polysomnography was performed in 21 patients with heart failure and SDB. Two 10-minute segments each of SDB and stable breathing from each patient were visually identified and ECG signal exported for HRV analysis. SDB increased total power (TP) with very low frequency (VLF) power accounting for the greatest increase (1.89±0.54 vs 2.96±0.46 ms2, P <0.001); LF/HF ratio increased during SDB (1.2±1.0 vs 2.7±2.1, P <0.001). Compared to OSA, CSA was associated with lower absolute LF (2.10±0.47 vs 2.52±0.55 ms2, P = 0.049) and HF power (1.69±0.41 vs 2.34±0.58 ms2, P = 0.004), increased VLF% (78.9%±13.4% vs 60.9%±19.2%, P = 0.008), decreased HF% (6.9%±7.8% vs 16.0%±11.7%, P = 0.046) with a trend to higher LF/HF ratio. Conclusions: SDB increases HRV in the setting of increased sympathetic dominance. HRV in CSA and OSA have unique HRV patterns which are likely to reflect the different pathophysiological mechanisms involved. Citation: Szollosi I; Krum H; Kaye D; Naughton MT. Sleep apnea in heart failure increases heart rate variability and sympathetic dominance. SLEEP 2007;30(11):1509-1514. PMID:18041483

  18. Comparison of electromigration failure rates and grain boundary kinetics in aluminum lines and films

    NASA Astrophysics Data System (ADS)

    Hunt, H. Marc

    2000-10-01

    Electromigration failure times for aluminum-1% silicon interconnects, (0.8 mum thick and linewidths of 3--4 mum) were used to develop a self-consistent thermodynamic treatment of the kinetic process controlling the failure rate. The results imply a power law relationship exists between the driving force and the failure rate, rather than the linear relationship predicted by basic electromigration flux theory. Additionally, the rate controlling process is predicted to require the coordinated motion of multiple atoms, rather than that of individual vacancy diffusion. Evolution of the grain structure during electromigration testing was evaluated for interconnects with-and without an impressed current. The grain structure and the behavior of individual grain boundaries for these aluminum films were evaluated by generating images that revealed the individual grains within the aluminum. These images were obtained using a dual beam FEI 620 Focused Ion Beam scanning electron microscope (FIB), which relies on differences in ion channeling between grain orientations to develop contrast in the secondary electron signal due to ion bombardment. Significant microstructural evolution was observed in regions exhibiting typical electromigration induced damage of void nucleation and growth. No significant changes to the basic microstructure of the interconnects was observed in regions away from the damage sites nor in the interconnects without an impressed current. These observations suggest the microstructural evolution was not solely driven by thermal activation, but possessed a contribution from the impressed current or electric field. In each case, the microstructural development resulted in void nucleation and growth. It was concluded, interactions between the applied field and the aluminum's microstructure contributed to localized microstructural evolution that resulted in void nucleation and growth.

  19. 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)…

  20. SLAP Repairs With Combined Procedures Have Lower Failure Rate Than Isolated Repairs in a Military Population

    PubMed Central

    Waterman, Brian R.; Arroyo, William; Heida, Kenneth; Burks, Robert; Pallis, Mark

    2015-01-01

    Background: Injuries to the superior glenoid labrum represent a significant cause of shoulder pain among active patients. The physical requirements of military service may contribute to an increased risk of injury. Limited data are available regarding the success of superior labral anterior posterior (SLAP) repairs in an active military population. Purpose: To quantify the rate of clinical failure and surgical revision after isolated and combined SLAP repair. Study Design: Cohort study; Level of evidence, 3. Methods: All consecutive active-duty servicemembers undergoing arthroscopic repair of type II SLAP lesions at a single institution between 2006 and 2012 were identified. Patients with less than 2-year clinical follow-up and nonmilitary status were excluded. Demographic variables, surgical variables, and occupational outcomes were extracted from electronic medical records and confirmed with the US Army Physical Disability Agency database. Failure was defined as subsequent revision surgery or medical discharge with persistent shoulder complaints. Results: A total of 192 patients with SLAP repair were identified with a mean follow-up of 50.0 months (SD, 17.0 months). Isolated SLAP repair occurred in 31.3% (n = 60) versus 68.8% (n = 132) with concomitant procedures. At final follow-up, 37.0% (n = 71) of patients reported some subjective activity-related shoulder pain. Postoperative return to duty occurred in 79.6% (n = 153), and only 20.3% (n = 39) were discharged with continuing shoulder disability. The combined rotator cuff repair (96%; P = .023) and anteroinferior labral repair group (88%; P = .056) had a higher rate of functional return than isolated SLAP repair (70%). Thirty-one (16.1%) patients were classified as surgical failure and required revision. Of these, the majority of patients undergoing biceps tenodesis (76%) returned to active duty, as compared with revision SLAP repair (17%). Lower demand occupation and the presence of combined shoulder injuries

  1. The failure of brittle materials under overall compression: Effects of loading rate and defect distribution

    NASA Astrophysics Data System (ADS)

    Paliwal, Bhasker

    The constitutive behaviors and failure processes of brittle materials under far-field compressive loading are studied in this work. Several approaches are used: experiments to study the compressive failure behavior of ceramics, design of experimental techniques by means of finite element simulations, and the development of micro-mechanical damage models to analyze and predict mechanical response of brittle materials under far-field compression. Experiments have been conducted on various ceramics, (primarily on a transparent polycrystalline ceramic, aluminum oxynitride or AlON) under loading rates ranging from quasi-static (˜ 5X10-6) to dynamic (˜ 200 MPa/mus), using a servo-controlled hydraulic test machine and a modified compression Kolsky bar (MKB) technique respectively. High-speed photography has also been used with exposure times as low as 20 ns to observe the dynamic activation, growth and coalescence of cracks and resulting damage zones in the specimen. The photographs were correlated in time with measurements of the stresses in the specimen. Further, by means of 3D finite element simulations, an experimental technique has been developed to impose a controlled, homogeneous, planar confinement in the specimen. The technique can be used in conjunction with a high-speed camera to study the in situ dynamic failure behavior of materials under confinement. AlON specimens are used for the study. The statically pre-compressed specimen is subjected to axial dynamic compressive loading using the MKB. Results suggest that confinement not only increases the load carrying capacity, it also results in a non-linear stress evolution in the material. High-speed photographs also suggest an inelastic deformation mechanism in AlON under confinement which evolves more slowly than the typical brittle-cracking type of damage in the unconfined case. Next, an interacting micro-crack damage model is developed that explicitly accounts for the interaction among the micro-cracks in

  2. 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…

  3. 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

  4. 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…

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Rates of Effort Test Failure in Children With ADHD: An Exploratory Study.

    PubMed

    Harrison, Allyson G; Flaro, Lloyd; Armstrong, Irene

    2015-01-01

    The present study assessed performance on symptom validity tests (SVTs) and various cognitive-processing measures to evaluate the impact of having attention-deficit hyperactivity disorder (ADHD) on SVT performance using a clinical sample of 73 children aged 7 to 18 years old who had a previous diagnosis of ADHD. Cognitive impairment associated with ADHD may lead these individuals to perform poorly on what are considered to be relatively easy but boring SVTs. Few clients in this sample returned a score pattern on the Word Memory Test, Medical Symptom Validity Test, or Nonverbal Medical Symptom Validity Test that would have classified them as having invested poor effort; the Computerized Assessment of Response Bias returned higher rates of failure. In the absence of a lifelong history of severe attention and impulse control problems, and especially where secondary gains exist for obtaining a diagnosis, clinicians should interpret low scores on these SVTs as indicating low effort or noncredible performance as opposed to failure due to the symptoms of ADHD. PMID:25257943

  13. 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

  14. Failure rates and complications of interspinous process decompression devices: a European multicenter study.

    PubMed

    Gazzeri, Roberto; Galarza, Marcelo; Neroni, Massimiliano; Fiore, Claudio; Faiola, Andrea; Puzzilli, Fabrizio; Callovini, Giorgio; Alfieri, Alex

    2015-10-01

    OBJECT Spacers placed between the lumbar spinous processes represent a promising surgical treatment alternative for a variety of spinal pathologies. They provide an unloading distractive force to the stenotic motion segment, restoring foraminal height, and have the potential to relieve symptoms of degenerative disc disease. The authors performed a retrospective, multicenter nonrandomized study consisting of 1108 patients to evaluate implant survival and failure modes after the implantation of 8 different interspinous process devices (IPDs). METHODS The medical records of patients who had undergone placement of an IPD were retrospectively evaluated, and demographic information, diagnosis, and preoperative pain levels were recorded. Preoperative and postoperative clinical assessments in the patients were based on the visual analog scale. A minimum of 3 years after IPD placement, information on long-term outcomes was obtained from additional follow-up or from patient medical and radiological records. RESULTS One thousand one hundred eight patients affected by symptomatic 1- or 2-level segmental lumbar spine degenerative disease underwent placement of an IPD. The complication rate was 7.8%. There were 27 fractures of the spinous process and 23 dura mater tears with CSF leakage. The ultimate failure rate requiring additional surgery was 9.6%. The reasons for revision, which always involved removal of the original implant, were acute worsening of low-back pain or lack of improvement (45 cases), recurrence of symptoms after an initial good outcome (42 cases), and implant dislocation (20 cases). CONCLUSIONS The IPD is not a substitute for a more invasive 3-column fusion procedure in cases of major instability and spondylolisthesis. Overdistraction, poor bone density, and poor patient selection may all be factors in the development of complications. Preoperatively, careful attention should be paid to bone density, appropriate implant size, and optimal patient selection

  15. 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.

  16. The decreased oxygen uptake during progressive exercise in ischemia-induced heart failure is due to reduced cardiac output rate.

    PubMed

    Rolim, N P L; Mattos, K C; Brum, P C; Baldo, M V C; Middlekauff, H R; Negrão, C E

    2006-02-01

    We tested the hypothesis that the inability to increase cardiac output during exercise would explain the decreased rate of oxygen uptake (VO2) in recent onset, ischemia-induced heart failure rats. Nine normal control rats and 6 rats with ischemic heart failure were studied. Myocardial infarction was induced by coronary ligation. VO2 was measured during a ramp protocol test on a treadmill using a metabolic mask. Cardiac output was measured with a flow probe placed around the ascending aorta. Left ventricular end-diastolic pressure was higher in ischemic heart failure rats compared with normal control rats (17 +/- 0.4 vs 8 +/- 0.8 mmHg, P = 0.0001). Resting cardiac index (CI) tended to be lower in ischemic heart failure rats (P = 0.07). Resting heart rate (HR) and stroke volume index (SVI) did not differ significantly between ischemic heart failure rats and normal control rats. Peak VO2 was lower in ischemic heart failure rats (73.72 +/- 7.37 vs 109.02 +/- 27.87 mL min(-1) kg(-1), P = 0.005). The VO2 and CI responses during exercise were significantly lower in ischemic heart failure rats than in normal control rats. The temporal response of SVI, but not of HR, was significantly lower in ischemic heart failure rats than in normal control rats. Peak CI, HR, and SVI were lower in ischemic heart failure rats. The reduction in VO2 response during incremental exercise in an ischemic model of heart failure is due to the decreased cardiac output response, largely caused by depressed stroke volume kinetics.

  17. 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.

  18. Heart failure performance measures: do they have an impact on 30-day readmission rates?

    PubMed

    Mazimba, Sula; Grant, Nakash; Parikh, Analkumar; Mwandia, George; Makola, Diklar; Chilomo, Christine; Redko, Cristina; Hahn, Harvey S

    2013-01-01

    Congestive heart failure (CHF) accounts for more health care costs than any other diagnosis. Readmissions contribute to this expenditure. The authors evaluated the relationship between adherence to performance metrics and 30-day readmissions. This was a retrospective study of 6063 patients with CHF between 2001 and 2008. Data were collected for 30-day readmissions and compliance with CHF performance measures at discharge. Rates of readmission for CHF increased from 16.8% in 2002 to 24.8% in 2008. Adherence to performance measures increased concurrently from 95.8% to 99.9%. Except for left ventricular function (LVF) assessment, the 30-day readmission rate was not associated with adherence to performance measures. Readmitted patients had twice the odds of not having their LVF assessed (odds ratio = 2.0; P < .00005; 95% confidence interval = 1.45-2.63). CHF performance measures, except for the LVF assessment, have little relationship to 30-day readmissions. Further studies are needed to identify performance measures that correlate with quality of care. PMID:23110998

  19. 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.

  20. 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. PMID:25586130

  1. 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

  2. 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.

  3. 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

    2016-11-01

    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.

  4. 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

  5. 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

  6. 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.

  7. Material Selection for an Ultra High Strength Steel Component Based on the Failure Criteria of CrachFEM

    SciTech Connect

    Kessler, L.; Beier, Th.; Werner, H.; Horstkott, D.; Dell, H.; Gese, H.

    2005-08-05

    An increasing use of combining more than one process step is noticed for coupling crash simulations with the results of forming operations -- mostly by inheriting the forming history like plastic strain and material hardening. Introducing a continuous failure model allows a further benefit of these coupling processes; it sometimes can even be the most attractive result of such a work. In this paper the algorithm CrachFEM for fracture prediction has been used to generate more benefit of the successive forming and crash simulations -- especially for ultra high strength steels. The choice and selection of the material grade in combination with the component design can therefore be done far before the prototyping might show an unsuccessful crash result; and in an industrial applicable manner.

  8. 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.

  9. Effect of fulminant hepatic failure porcine plasma supplemented with essential components on encapsulated rat hepatocyte spheroids.

    PubMed

    Lee, J-H; Lee, D-H; Park, J-K; Kim, S-K; Kwon, C H D; Lee, S-K

    2012-05-01

    The development of bioartificial liver (BAL) systems has required detailed information about the functional capabilities of cultured hepatocytes during blood or plasma passage. In this study we investigated the effects of porcine plasma and various supplements on the viability and function of adult rat hepatocytes in vitro. Primary rat hepatocytes cultured in porcine plasma supplemented with various substances showed albumin synthesis rates and viability equal to or higher than those of controls. Supplementation with calcium chloride, magnesium sulfate, trace elements, amino acids, insulin, and epidermal growth factor were essential to maintain viability and high albumin synthesis. Especially, trace elements showed significantly higher and longer albumin secretion. Isolated rat hepatocytes were cultured in Spinner flasks for 24 hours to form spheroids that were harvested and encapsulated with chitosan-alginate solution before transfer to the bioreactor in the BAL system. Encapsulated rat hepatocyte spheroids cultured with porcine plasma including trace elements showed higher viability (57%) than controls (40%) after 24 hours, with ammonia removal values of 30.92 μg/10(6) cells versus the control 9.04 μg/10(6) cells. After 24 hours of operation the urea secretion value of encapsulated rat hepatocyte spheroids cultured in porcine plasma in the presence versus absence of trace elements was 76.73 μg/10(6) cells and 18.80 μg/10(6) cells, respectively. We concluded that encapsulated hepatocyte spheroids in a packed-bed bioreactor operated with human plasma including trace elements enhanced cell viability and liver function as a bases for an in vivo clinical trial of the BAL system. PMID:22564611

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

    PubMed

    DeCesare, Nicholas J

    2012-11-22

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

    PubMed

    DeCesare, Nicholas J

    2012-11-22

    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.

  12. 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

  13. 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.

  14. 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.

  15. Testosterone Deficiency Increases Hospital Readmission and Mortality Rates in Male Patients with Heart Failure

    PubMed Central

    dos Santos, Marcelo Rodrigues; Sayegh, Ana Luiza Carrari; Groehs, Raphaela Vilar Ramalho; Fonseca, Guilherme; Trombetta, Ivani Credidio; Barretto, Antônio Carlos Pereira; Arap, Marco Antônio; Negrão, Carlos Eduardo; Middlekauff, Holly R.; Alves, Maria-Janieire de Nazaré Nunes

    2015-01-01

    Background Testosterone deficiency in patients with heart failure (HF) is associated with decreased exercise capacity and mortality; however, its impact on hospital readmission rate is uncertain. Furthermore, the relationship between testosterone deficiency and sympathetic activation is unknown. Objective We investigated the role of testosterone level on hospital readmission and mortality rates as well as sympathetic nerve activity in patients with HF. Methods Total testosterone (TT) and free testosterone (FT) were measured in 110 hospitalized male patients with a left ventricular ejection fraction < 45% and New York Heart Association classification IV. The patients were placed into low testosterone (LT; n = 66) and normal testosterone (NT; n = 44) groups. Hypogonadism was defined as TT < 300 ng/dL and FT < 131 pmol/L. Muscle sympathetic nerve activity (MSNA) was recorded by microneurography in a subpopulation of 27 patients. Results Length of hospital stay was longer in the LT group compared to in the NT group (37 ± 4 vs. 25 ± 4 days; p = 0.008). Similarly, the cumulative hazard of readmission within 1 year was greater in the LT group compared to in the NT group (44% vs. 22%, p = 0.001). In the single-predictor analysis, TT (hazard ratio [HR], 2.77; 95% confidence interval [CI], 1.58–4.85; p = 0.02) predicted hospital readmission within 90 days. In addition, TT (HR, 4.65; 95% CI, 2.67–8.10; p = 0.009) and readmission within 90 days (HR, 3.27; 95% CI, 1.23–8.69; p = 0.02) predicted increased mortality. Neurohumoral activation, as estimated by MSNA, was significantly higher in the LT group compared to in the NT group (65 ± 3 vs. 51 ± 4 bursts/100 heart beats; p < 0.001). Conclusion These results support the concept that LT is an independent risk factor for hospital readmission within 90 days and increased mortality in patients with HF. Furthermore, increased MSNA was observed in patients with LT. PMID:26200897

  16. Performance analysis of multi-radio routing protocol in cognitive radio ad hoc networks under different path failure rate

    NASA Astrophysics Data System (ADS)

    Che-Aron, Z.; Abdalla, A. H.; Abdullah, K.; Hassan, W. H.

    2013-12-01

    In recent years, Cognitive Radio (CR) technology has largely attracted significant studies and research. Cognitive Radio Ad Hoc Network (CRAHN) is an emerging self-organized, multi-hop, wireless network which allows unlicensed users to opportunistically access available licensed spectrum bands for data communication under an intelligent and cautious manner. However, in CRAHNs, a lot of failures can easily occur during data transmission caused by PU (Primary User) activity, topology change, node fault, or link degradation. In this paper, an attempt has been made to evaluate the performance of the Multi-Radio Link-Quality Source Routing (MR-LQSR) protocol in CRAHNs under different path failure rate. In the MR-LQSR protocol, the Weighted Cumulative Expected Transmission Time (WCETT) is used as the routing metric. The simulations are carried out using the NS-2 simulator. The protocol performance is evaluated with respect to performance metrics like average throughput, packet loss, average end-to-end delay and average jitter. From the simulation results, it is observed that the number of path failures depends on the PUs number and mobility rate of SUs (Secondary Users). Moreover, the protocol performance is greatly affected when the path failure rate is high, leading to major service outages.

  17. 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. PMID:18796349

  18. Contrast and reallocation of extraneous reinforcers as a function of component duration and baseline rate of reinforcement

    PubMed Central

    McLean, Anthony P.

    1995-01-01

    Four pigeons responded on multiple schedules arranged on a “main” key in a two-key experimental chamber. A constant schedule component was alternated with another component that was varied over conditions. On an extra response key, conjoint schedules of reinforcement that operated in both components were arranged concurrently with the multiple schedule on the main key. On the main key, changes in reinforcement rate in the varied component were inversely related to changes in response rates in the constant component (behavioral contrast). On the extra key, some reinforcers were reallocated between components, depending on the schedules in effect on the main key in the varied component. In the varied component, the obtained rates of reinforcement on the extra key were inversely related to main-key reinforcement rate. In the constant component, extra-key reinforcer rates were positively related to main-key reinforcer rates obtained in the varied component, and were not a function of response rates on the extra key. In two comparisons, the rate at which components alternated and the value of the main-key schedule in the constant component were varied. Consistent with earlier work, long components reduced the extent of contrast. Reductions in contrast as a function of component duration were accompanied by similar reductions in the extent of reinforcer reallocation on the extra key. In the second comparison, lowering the rate of reinforcement in the constant component increased the rate at which extra-key reinforcers were obtained, reduced the extent of reinforcer reallocation, and reduced contrast. Overall, the results are consistent with the suggestion that some contrast effects are due to the changes in extraneous reinforcement during the constant component, and that manipulations of component duration, and manipulations of the rate of reinforcement in the constant component, affect contrast because they influence the extent of extraneous reinforcer real

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

    DOE PAGESBeta

    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.; et al

    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

  20. Clinical evaluation of removable partial dentures 10 years after insertion: success rates, hygienic problems, and technical failures.

    PubMed

    Wagner, B; Kern, M

    2000-06-01

    The aim of this retrospective study was to examine the condition and success rate of various designs of removable partial dentures 10 years after placement. Seventy-four patients treated with 101 mainly conical crown-retained dentures (CCRDs), clasp-retained removable partial dentures (RPDs), or a combination of conical crown and clasp-retained dentures (CRPDs) were reexamined. Prosthetic findings were compared to baseline values at insertion and checked for factors that may affect them. Overall, 36.6% of the prostheses were regarded as successes, 23.8% as partial successes, and 39.6% as failures. Also, only one-third of the prostheses showed neither hygienic problems nor technical failures. The statistical analysis identified no single parameter as significantly affecting the success rate of the partial dentures. Prostheses supported by several abutment teeth had improved success, and RPDs had a higher failure rate (66.7%) than CCRDs (33.3%) and CRPDs (44.8%); however, because of the limited number of RPDs these differences were not statistically significant. Although the prostheses were unsupervised in service, the 60.4% overall success rate of the dentures was somewhat higher than in other studies on precision-retained prostheses.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    PubMed

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

    2016-08-01

    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, 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.

  7. 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

  8. Effect of Safety Measures on Bacterial Contamination Rates of Blood Components in Germany

    PubMed Central

    Walther-Wenke, Gabriele; Däubener, Walter; Heiden, Margarethe; Hoch, Jochen; Hornei, Britt; Volkers, Peter; von König, Carl Heinz Wirsing

    2011-01-01

    Summary Requirements for bacterial testing of blood components on a defined quantity as part of routine quality control were introduced in Germany by the National Advisory Committee Blood of the German Federal Ministry of Health in 1997. The philosophy was to establish standardized methods for bacterial testing. Numerous measures to reduce the risk of bacterial contamination were implemented into the blood donation and manufacturing processes between 1999 and 2002. German Blood establishments performed culture-based bacterial testing on random samples of platelet concentrates (PCs), red blood cells (RBCs) and fresh frozen plasma (FFP) and reported data out of the production periods 1998, 2001 and 2005/2006. While the bacterial contamination rate of apheresis PCs remained nearly unchanged, it decreased by 70% for pooled PCs to a rate of 0.158% in the last observation period. Leukocyte-depleted RBCs with diversion of the initial blood volume showed a contamination rate of 0.029% which is significantly lower than that of RBCs without leukocyte depletion and diversion (0.157%). The contamination rate of plasma decreased by 80%. Preventive measures resulted in a significant reduction of bacterial contamination of blood components. Long-term monitoring with standardized methods for bacteria testing supports evaluation of the cumulative effect of contamination reducing measures. PMID:22016691

  9. 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.

  10. [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. PMID:26390653

  11. The effect of 12C + 12C rate uncertainties on the weak s-process component

    SciTech Connect

    Fryer, Christopher Lee; Hungerford, Aimee L; Hirschi, Raphael; Pignatari, Marco; Bennett, Michael E; Diehl, Steven; Herwig, Falk; Hillary, William; Richman, Debra; Rockefeller, Gabriel; Timmes, Frank X; Wiescher, Michael

    2010-09-10

    The contribution by massive stars (M > 15M{sub {circle_dot}}) to the weak s-process component of the solar system abundances is primarily due to the {sup 22}Ne neutron source, which is activated near the end of helium-core burning. The residual {sup 22}Ne left over from helium-core burning is then reignited during carbon burning, initiating further s-processing that modifies the isotopic distribution. This modification is sensitive to the stellar structure and the carbon burning reaction rate. Recent work on the {sup 12}C + {sup 12}C reaction suggests that resonances located within the Gamow peak may exist, causing a strong increase in the astrophysical S-factor and consequently the reaction rate. To investigate the effect of such a rate, 25M{sub {circle_dot}} stellar models with different carbon burning rates, at solar metallicity, were generated using the Geneva Stellar Evolution Code (GENEC) with nucleosynthesis post-processing calculated using the NuGrid Multi-zone Post-Processing Network code (MPPNP). A strongly enhanced rate can cause carbon burning to occur in a convective core rather than a radiative one and the convective core mixes the matter synthesized there up into the carbon shell, significantly altering the initial composition of the carbon-shell. In addition, an enhanced rate causes carbon-shell burning episodes to ignite earlier in the evolution of the star, igniting the {sup 22}Ne source at lower temperatures and reducing the neutron density.

  12. 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.

  13. 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

  14. Comparison of the accuracy and proximal shunt failure rate of freehand placement versus intraoperative guidance in parietooccipital ventricular catheter placement.

    PubMed

    Wilson, Thomas J; McCoy, Kathleen E; Al-Holou, Wajd N; Molina, Sergio L; Smyth, Matthew D; Sullivan, Stephen E

    2016-09-01

    .424, 95% CI 1.796-6.524; p = 0.009) increased the likelihood. CONCLUSIONS The use of intraoperative guidance during parietooccipital ventricular catheter placement as part of a CSF shunt system significantly increases the likelihood of accurate catheter placement and subsequently reduces the rate of proximal shunt failure. PMID:27581306

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Prediction of Hospital Acute Myocardial Infarction and Heart Failure 30-Day Mortality Rates Using Publicly Reported Performance Measures

    PubMed Central

    Aaronson, David S.; Bardach, Naomi S.; Lin, Grace A.; Chattopadhyay, Arpita; Goldman, L. Elizabeth; Dudley, R. Adams

    2014-01-01

    Objective To identify an approach to summarizing publicly reported hospital performance data for acute myocardial infarction (AMI) or heart failure (HF) that best predicts current year hospital mortality rates. Setting A total of 1,868 U.S. hospitals reporting process and outcome measures for AMI and HF to the Centers for Medicare and Medicaid Services (CMS) from July 2005 to June 2006 (Year 0) and July 2006 to June 2007 (Year 1). Design Observational cohort study measuring the percentage variation in Year 1 hospital 30-day risk-adjusted mortality rate explained by denominator-based weighted composite scores summarizing hospital Year 0 performance. Data Collection Data were prospectively collected from hospitalcompare.gov. Results Percentage variation in Year 1 mortality was best explained by mortality rate alone in Year 0 over other composites including process performance. If only Year 0 mortality rates were reported, and consumers using hospitals in the highest decile of mortality instead chose hospitals in the lowest decile of mortality rate, the number of deaths at 30 days that potentially could have been avoided was 1.31 per 100 patients for AMI and 2.12 for HF (p < .001). Conclusion Public reports focused on 30-day risk-adjusted mortality rate may more directly address policymakers’ goals of facilitating consumer identification of hospitals with better outcomes. PMID:22093186

  2. 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

  3. Digoxin Use to Control Ventricular Rate in Patients with Atrial Fibrillation and Heart Failure Is Not Associated with Increased Mortality

    PubMed Central

    Dominic, Paari

    2015-01-01

    Introduction. Digoxin is used to control ventricular rate in atrial fibrillation (AF). There is conflicting evidence regarding safety of digoxin. We aimed to evaluate the risk of mortality with digoxin use in patients with AF using meta-analyses. Methods. PubMed was searched for studies comparing outcomes of patients with AF taking digoxin versus no digoxin, with or without heart failure (HF). Studies were excluded if they reported only a point estimate of mortality, duplicated patient populations, and/or did not report adjusted hazard ratios (HR). The primary endpoint was all-cause mortality. Adjusted HRs were combined using generic inverse variance and log hazard ratios. A multivariate metaregression model was used to explore heterogeneity in studies. Results. Twelve studies with 321,944 patients were included in the meta-analysis. In all AF patients, irrespective of heart failure status, digoxin is associated with increased all-cause mortality (HR [1.23], 95% confidence interval [CI] 1.16–1.31). However, digoxin is not associated with increased mortality in patients with AF and HF (HR [1.08], 95% CI 0.99–1.18). In AF patients without HF digoxin is associated with increased all-cause mortality (HR [1.38], 95% CI 1.12–1.71). Conclusion. In patients with AF and HF, digoxin use is not associated with an increased risk of all-cause mortality when used for rate control. PMID:26788401

  4. 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

    ... and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF... CAPITAL Minimum Capital Pt. 1750, Subpt. A, App. A Appendix A to Subpart A of Part 1750—Minimum Capital... sheet interest rate and foreign exchange rate contracts: a. Interest Rate Contracts i. Single...

  5. 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

    ... and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF... CAPITAL Minimum Capital Pt. 1750, Subpt. A, App. A Appendix A to Subpart A of Part 1750—Minimum Capital... sheet interest rate and foreign exchange rate contracts: a. Interest Rate Contracts i. Single...

  6. 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

    ... and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF... CAPITAL Minimum Capital Pt. 1750, Subpt. A, App. A Appendix A to Subpart A of Part 1750—Minimum Capital... sheet interest rate and foreign exchange rate contracts: a. Interest Rate Contracts i. Single...

  7. 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

    ... and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF... CAPITAL Minimum Capital Pt. 1750, Subpt. A, App. A Appendix A to Subpart A of Part 1750—Minimum Capital... sheet interest rate and foreign exchange rate contracts: a. Interest Rate Contracts i. Single...

  8. 12 CFR Appendix A to Subpart A of... - Minimum Capital Components for Interest Rate and Foreign Exchange Rate Contracts

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... and Foreign Exchange Rate Contracts A Appendix A to Subpart A of Part 1750 Banks and Banking OFFICE OF... CAPITAL Minimum Capital Pt. 1750, Subpt. A, App. A Appendix A to Subpart A of Part 1750—Minimum Capital... sheet interest rate and foreign exchange rate contracts: a. Interest Rate Contracts i. Single...

  9. Uncemented Porous Tantalum Acetabular Components: Early Follow-Up and Failures in 599 Revision Total Hip Arthroplasties

    PubMed Central

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

    2015-01-01

    Background The purpose of this study was to determine the early outcomes of 599 cases of revision THA performed using a porous tantalum cup. Methods Clinical and radiographic data was sought in all patients at a minimum two years follow-up, after acetabular revision performed with a porous tantalum cup. Results Of the 599 cases identified, there were 51 re-operations in 47 patients (7.8 percent). Cup removal was required in 14 of these cases (2.3 percent). The most common cause for cup removal was a septic joint (12). No cups were revised for aseptic loosening during the study period. There was one case of early cup migration. There were 17 incomplete lucencies not initially seen on post-operative films, but identified later, all were non-progressive on subsequent x-rays. Conclusions Early results of porous tantalum acetabular components in the revision setting demonstrate good initial stability and low re-operation rates at two years follow-up. Level of Evidence Level 4: Case series PMID:26361451

  10. 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

  11. Optimal Cardiac Resynchronization Therapy Pacing Rate in Non-Ischemic Heart Failure Patients: A Randomized Crossover Pilot Trial

    PubMed Central

    Ghotbi, Adam Ali; Sander, Mikael; Køber, Lars; Philbert, Berit Th.; Gustafsson, Finn; Hagemann, Christoffer; Kjær, Andreas; Jacobsen, Peter K.

    2015-01-01

    Background The optimal pacing rate during cardiac resynchronization therapy (CRT) is unknown. Therefore, we investigated the impact of changing basal pacing frequencies on autonomic nerve function, cardiopulmonary exercise capacity and self-perceived quality of life (QoL). Methods Twelve CRT patients with non-ischemic heart failure (NYHA class II–III) were enrolled in a randomized, double-blind, crossover trial, in which the basal pacing rate was set at DDD-60 and DDD-80 for 3 months (DDD-R for 2 patients). At baseline, 3 months and 6 months, we assessed sympathetic nerve activity by microneurography (MSNA), peak oxygen consumption (pVO2), N-terminal pro-brain natriuretic peptide (p-NT-proBNP), echocardiography and QoL. Results DDD-80 pacing for 3 months increased the mean heart rate from 77.3 to 86.1 (p = 0.001) and reduced sympathetic activity compared to DDD-60 (51±14 bursts/100 cardiac cycles vs. 64±14 bursts/100 cardiac cycles, p<0.05). The mean pVO2 increased non-significantly from 15.6±6 mL/min/kg during DDD-60 to 16.7±6 mL/min/kg during DDD-80, and p-NT-proBNP remained unchanged. The QoL score indicated that DDD-60 was better tolerated. Conclusion In CRT patients with non-ischemic heart failure, 3 months of DDD-80 pacing decreased sympathetic outflow (burst incidence only) compared to DDD-60 pacing. However, Qol scores were better during the lower pacing rate. Further and larger scale investigations are indicated. Trial Registration ClinicalTrials.gov NCT02258061 PMID:26382243

  12. 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.

  13. 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.

  14. 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.

  15. 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. At NASA's Lewis Research Center, methods and facilities have been developed for evaluating these new technologies in the laboratory. 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. This paper describes 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.

  16. 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.

  17. 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

    2016-04-01

    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.

  18. 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

    2016-04-01

    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. PMID:27052834

  19. Cluster failure: Why fMRI inferences for spatial extent have inflated false-positive rates

    PubMed Central

    Eklund, Anders; Nichols, Thomas E.; Knutsson, Hans

    2016-01-01

    The most widely used task functional magnetic resonance imaging (fMRI) analyses use parametric statistical methods that depend on a variety of assumptions. In this work, we use real resting-state data and a total of 3 million random task group analyses to compute empirical familywise error rates for the fMRI software packages SPM, FSL, and AFNI, as well as a nonparametric permutation method. For a nominal familywise error rate of 5%, the parametric statistical methods are shown to be conservative for voxelwise inference and invalid for clusterwise inference. Our results suggest that the principal cause of the invalid cluster inferences is spatial autocorrelation functions that do not follow the assumed Gaussian shape. By comparison, the nonparametric permutation test is found to produce nominal results for voxelwise as well as clusterwise inference. These findings speak to the need of validating the statistical methods being used in the field of neuroimaging. PMID:27357684

  20. Cluster failure: Why fMRI inferences for spatial extent have inflated false-positive rates.

    PubMed

    Eklund, Anders; Nichols, Thomas E; Knutsson, Hans

    2016-07-12

    The most widely used task functional magnetic resonance imaging (fMRI) analyses use parametric statistical methods that depend on a variety of assumptions. In this work, we use real resting-state data and a total of 3 million random task group analyses to compute empirical familywise error rates for the fMRI software packages SPM, FSL, and AFNI, as well as a nonparametric permutation method. For a nominal familywise error rate of 5%, the parametric statistical methods are shown to be conservative for voxelwise inference and invalid for clusterwise inference. Our results suggest that the principal cause of the invalid cluster inferences is spatial autocorrelation functions that do not follow the assumed Gaussian shape. By comparison, the nonparametric permutation test is found to produce nominal results for voxelwise as well as clusterwise inference. These findings speak to the need of validating the statistical methods being used in the field of neuroimaging. PMID:27357684

  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. Acupuncture to Danzhong but not to Zhongting increases the cardiac vagal component of heart rate variability.

    PubMed

    Kurono, Yasuzo; Minagawa, Munenori; Ishigami, Tatsuyo; Yamada, Atsushi; Kakamu, Toshinori; Hayano, Junichiro

    2011-04-26

    There is currently no convincing evidence that acupuncture has any specific effects on autonomic nervous function as assessed by heart rate variability (HRV). We examined whether the stimulation of neighboring acupunctural points, Danzhong (CV17) and Zhongting (CV16) on the anterior median line of the thorax, induced different effects on HRV. In 14 healthy males, epifascial acupunctural stimulation (single instantaneous needle stimulation on the fascial surface without producing De-Qi sensation) was performed at CV17 and CV16 on different days in a clinical study utilizing a cross-over design. We found that the stimulation of CV17, but not of CV16, decreased the heart rate (P=0.01, repeated measures ANOVA) and increased the power of the high-frequency component of the HRV, an index of cardiac vagal activity (P=0.01). The low-frequency to high-frequency ratio, an index of sympathetic activity showed no significant changes for either point. Our observations could not be explained as either nonspecific or psychological/placebo effects of needle stimulation. This study provides strong evidence for the presence of a specific acupunctural point that causes the modulation of cardiac autonomic function. PMID:21216208

  3. 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.

  4. 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.

  5. The Accretion Rates and White Dwarf Components of Nova-Like Cataclysmic Variables

    NASA Astrophysics Data System (ADS)

    Mizusawa, Trisha; Merritt, J.; Bonaro, M.; Foran, S.; Plumberg, C.; Stewart, H.; Wiley, T.; Ballouz, R.; Sion, E.

    2009-01-01

    We present the results of a multi-component synthetic spectral analysis of the archival far ultraviolet spectra of several key nova-like variables including members of the SW Sex, RW Tri, UX UMa and VY Scl subclasses: KR Aur, V795 Her, BP Lyn, V825 Her, HL Aqr, RW Tri and V425 Cas. Accretion rates as well as the flux contribution of the accreting white dwarf are included in our analysis. Except for RW Tri which has a reliable trigonometric parallax, we computed the distances to the nova-like systems using the method of Knigge(2006, MNRAS, 373, 484). For KR Aur, we find that the white dwarf has T_eff = 29,000 +/- 2000K, log g = 8.4 and contributes 18% of the FUV flux while an accretion disk with accretion rate Mdot = 3 x 10-10 Msun/yr at an inclination of 41 degrees, contributes the remainder. Our analysis of seven archival IUE spectra of RW Tri at its parallax distance consistently yields a low mass (0.4 Msun) white dwarf and an average accretion rate, Mdot = 6.3 x 10-9 Msun/yr. We find that an accreting white dwarf rather than accretion disk dominates the far UV spectrum of V425 Cas while HL Aqr's and V825 Her's FUV spectra are dominated by an accretion disk with Mdot = 1 x 10-9 Msun/yr and 3 x 10-9 Msun/yr, respectively. For BP Lyn we find Mdot = 1 x 10-8 Msun/yr and we explore the possiblity that V795 Her is an intermediate polar. We discuss the implications of our results for the evolutionary status of nova-like variables. This work is supported by NSF grant AST-0807892 to Villanova University and by the Delaware Space Grant Consortium

  6. Nonlinear dynamics of heart rate variability in response to orthostatism and hemodialysis in chronic renal failure patients: recurrence analysis approach.

    PubMed

    González, Hortensia; Infante, Oscar; Pérez-Grovas, Héctor; Jose, Marco V; Lerma, Claudia

    2013-02-01

    We studied the response of heart rate variability to hemodialysis and orthostatism using traditional linear indexes and 9 recurrence quantification analysis indexes to reveal changes in the heart rate dynamics. Twenty healthy subjects and 19 chronic renal failure patients treated with hemodialysis thrice a week were included. Five-minute heart rate variability time series were obtained during supine position (clinostatism) and orthostatism from each participant; recordings in renal patients were repeated after hemodialysis. Linear indexes were consistent with sympathetic predominance in response to orthostatism in the control group. Renal patients before hemodialysis showed increased sympathetic predominance in clinostatism, with further increase in orthostatism and hemodialysis. In response to orthostatism, 4 recurrence indexes changed in the control group, while in renal patients any of them changed before hemodialysis and 1 changed after hemodialysis. In clinostatism, renal patients (both before and after hemodialysis) had higher laminarity, trapping time, and recurrence time than the control group. Recurrence indexes showed that the heart rate dynamics in renal patients are different from healthy subjects, suggesting loss of access to some regulatory conditions. These findings are consistent with reports of sympathetic stimulation induced by hemodialysis and active standing.

  7. 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.

  8. Experimental and Numerical Investigation into the Effect of Strain Rate Changes on Failure of AA7075 at the Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Zand, H.; Zhalehfar, F.; Vafaeesefat, A.

    2016-08-01

    This paper represents the temperature-dependent study which is performed on AA7075. This was performed through the application of deep drawing experiments at high temperature of 250, 300, 350, 400, 450 and 500°C and different forming speeds. FEM study is applied at room and 300 and 400 0C temperature with different strain rates. Softening model is used to model the thermo-mechanical constitutive equation. Forming limit curve models (based on M-K model) were used in the analysis of simulation results in order to predict the onset of necking. Simulation results were compared with experimental data to evaluate the accuracy of onset of necking simulation and failure location prediction

  9. Reliability Performance in GPS Receivers and the Nature of Their Failures: Planning to Live with Realistic Failure Rates in Satellite Navigation System Receivers

    NASA Astrophysics Data System (ADS)

    Sharkey, Sarah; Johannessen, Rolf

    This paper and the following three papers were presented at the Institute's NAV-96 Conference, Where are we now?35 for members and Outages’) MTBO is presented along with the nature of some of the failures that have been encountered. The paper concludes with the operational implication of the findings.

  10. Plastic flow and failure in HY100, HY130 and AF1410 alloy steels under high strain rate and impact loading conditions

    NASA Astrophysics Data System (ADS)

    Rajendran, A. M.; Last, H. R.; Garrett, R. K., Jr.

    1995-03-01

    This report presents the results from impact experiments, constitutive/failure modeling, and metallurgical failure analyses for three steels: HY100, HY130, and AF1410. The main objectives of this effort are: (1) to obtain fundamental engineering data in terms of stress-strain curves up to failure at different temperatures and strain rates, (2) to evaluate the observed differences in the macroscopic behaviors through microscopic metallurgical studies, and (3) to describe the flow and failure behaviors using already available material strength and spall models. The high strain rate and impact experiments considered are the split Hopkinson bar (SHB) and the planar plate impact tests, respectively. In addition, the baseline data include quasi-static (QS) tests at low strain rates. The QS and SHB data provide stress-strain curves at different strain rates and temperatures. The experimental data illustrate the effects of two important loading parameters (strain rate and temperature) on the flow and failure behaviors of HY100, HY130, and AF1410 steels.

  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

    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

  12. Maladaptive correlates of the failure to forgive self and others: further evidence for a two-component model of forgiveness.

    PubMed

    Ross, Scott R; Hertenstein, Matthew J; Wrobel, Thomas A

    2007-04-01

    In a sample composed of 162 young adults, we examined the generalizability of an orthogonal, 2-component model of forgiveness previously reported by Ross, Kendall, Matters, Rye, and Wrobel (2004). Furthermore, we examined the relationship of these two components with maladaptive personality characteristics as measured by the Schedule for Nonadaptive and Adaptive Personality (SNAP; Clark, 1993), with an emphasis on Five-factor model markers of personality. Using multiple measures of forgiveness, principal components analysis supported a 2-component model representing self-forgiveness and other forgiveness. Despite the independence of self-forgiveness and other forgiveness, zero order correlations with SNAP scales supported convergent more than discriminant validity. In contrast, hierarchical multiple regression analyses emphasized the discriminant validity of self-forgiveness and other forgiveness. Among indices of Neuroticism, Extraversion, and Agreeableness, Negative Temperament (+) was the sole predictor of self-forgiveness. In contrast, Positive Temperament (+), Aggression (-), and Histrionic PD (-) were most associated with other forgiveness. Overall, these findings support the validity of these factors and highlight the importance of self-forgiveness in clinical assessment.

  13. [Change in cross-bridge activation rate constant (Kac) after six-minute walk in patients with heart failure].

    PubMed

    Takahashi, M; Takeda, K; Saotome, T; Kobayashi, N; Yagi, S

    1994-01-01

    Cardiac adrenergic activity is increased in patients with congestive heart failure (CHF) and is excessively increased during mild exercise. Changes in cardiac adrenergic activity were examined in normal individuals and patients with CHF before and after mild exercise using the cross-bridge activation rate constant (Ka), which may represent the adrenergic activity related to the working left ventricular myocardium. Ten normal volunteers and 31 patients with stable CHF underwent echocardiography. The left ventricular ejection fraction (LVEF) was measured in all the CHF patients using left ventriculography or radionuclide cineangiography. The patients were classified into two groups: group 1 with an LVEF > or = 50% (n = 16) and group 2 with an LVEF < 50% (n = 15). The cause of CHF was old myocardial infarction in 25 patients and dilated cardiomyopathy in 6. All subjects exercised by walking for 6 min after resting in the supine position for 30 min. The blood pressure, electrocardiogram, phonocardiogram, and M-mode echocardiogram were recorded simultaneously before and after exercise. The values of Ka and Kac (Ka corrected for the individual heart rate) were calculated from the QS2 interval and the heart rate (HR) as follows: Ka = 3/QS2 interval, and Kac = Ka +0.0249 (66-HR). Before exercise, the HR was significantly higher in group 2, but the Kac value showed no significant difference between all three groups. The increase of HR with exercise (delta HR) and the Kac value after exercise were not significantly different between all three groups.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7823284

  14. Growth rate consists of baseline and systematic deviation components in Thoroughbreds.

    PubMed

    Staniar, W B; Kronfeld, D S; Treiber, K H; Splan, R K; Harris, P A

    2004-04-01

    The objective of this study was to establish a procedure for differentiating a baseline curve from a systematic deviation in weight-age data, and hence to develop a physiological growth model for the Thoroughbred. A total of 2,698 records for 175 foals was obtained during a period of 8 yr (1994 to 2001). Weight-age data were fit with a sigmoid growth equation, W = A(1 + be(-kt))M, where W is BW at age t, A is the asymptotic value of W, b is a scaling parameter that defines the degree of maturity at t = 0, k is a rate constant, and M defines the point of inflection in the sigmoid curve in relation to age. Short-term systematic deviations in the weight-age data were identified by a goodness-of-fit procedure and illustrated in three-dimensional contour plots of the sigmoid equation parameters as they changed upon removal of selected subsets of the data. Based on features of the contour plots, a negative deviation between 210 and 420 d of age was set aside, with the remaining data establishing the baseline data set. The sigmoid growth equation was fit to the baseline data set using a nonlinear mixed model with repeated measures, and indicated a mature weight of 542 +/- 6.2 kg reached at 7 yr. The systematic deviation identified in this weight-age data set is present in other published Thoroughbred growth data and is likely to result in erroneous parameter estimates if not set aside before fitting sigmoid growth equations to the thus-modified weight-age data set. The techniques developed in this study enable identification of short-term systematic deviations in weight-age data and define a realistic baseline growth curve. Differentiation of these two components enables the development of a physiological model of growth that distinguishes between baseline growth and environmental influences, represented respectively, by the baseline curve and the systematic deviation. PMID:15080321

  15. Multiscale entropy analysis of heart rate variability in heart failure, hypertensive, and sinoaortic-denervated rats: classical and refined approaches.

    PubMed

    Silva, Luiz Eduardo Virgilio; Lataro, Renata Maria; Castania, Jaci Airton; da Silva, Carlos Alberto Aguiar; Valencia, Jose Fernando; Murta, Luiz Otavio; Salgado, Helio Cesar; Fazan, Rubens; Porta, Alberto

    2016-07-01

    The analysis of heart rate variability (HRV) by nonlinear methods has been gaining increasing interest due to their ability to quantify the complexity of cardiovascular regulation. In this study, multiscale entropy (MSE) and refined MSE (RMSE) were applied to track the complexity of HRV as a function of time scale in three pathological conscious animal models: rats with heart failure (HF), spontaneously hypertensive rats (SHR), and rats with sinoaortic denervation (SAD). Results showed that HF did not change HRV complexity, although there was a tendency to decrease the entropy in HF animals. On the other hand, SHR group was characterized by reduced complexity at long time scales, whereas SAD animals exhibited a smaller short- and long-term irregularity. We propose that short time scales (1 to 4), accounting for fast oscillations, are more related to vagal and respiratory control, whereas long time scales (5 to 20), accounting for slow oscillations, are more related to sympathetic control. The increased sympathetic modulation is probably the main reason for the lower entropy observed at high scales for both SHR and SAD groups, acting as a negative factor for the cardiovascular complexity. This study highlights the contribution of the multiscale complexity analysis of HRV for understanding the physiological mechanisms involved in cardiovascular regulation.

  16. Differential impact of mechanical unloading on structural and nonstructural components of the extracellular matrix in advanced human heart failure.

    PubMed

    Sakamuri, Siva S V P; Takawale, Abhijit; Basu, Ratnadeep; Fedak, Paul W M; Freed, Darren; Sergi, Consolato; Oudit, Gavin Y; Kassiri, Zamaneh

    2016-06-01

    Adverse remodeling of the extracellular matrix (ECM) is a significant characteristic of heart failure. Reverse remodeling of the fibrillar ECM secondary to mechanical unloading of the left ventricle (LV) by left ventricular assist device (LVAD) has been subject of intense investigation; however, little is known about the impacts on nonfibrillar ECM and matricellular proteins that also contribute to disease progression. Explanted failing hearts were procured from patients with nonischemic dilated cardiomyopathy (DCM) with or without LVAD support, and compared to nonfailing control hearts. LV free wall specimens were formalin-fixed, flash-frozen or optimum cutting temperature-mount frozen. Histologic and biochemical assessment of fibrillar ECM showed that LVAD support was associated with lower levels of insoluble collagen, collagen type I mRNA, and collagen I/III ratio compared with no-LVAD hearts. A disintegrin and Metalloproteinase with Thrombospondin Motifs-2 (ADAM-TS2), a procollagen endopeptidase, was reduced in no-LVAD but not in LVAD hearts. The rise in ECM proteolytic activities was significantly lower in LVAD hearts. Matrix metalloproteinases (MMP1, MMP2, MMP8, MMP13, and MT1-MMP/MMP14) were comparable between DCM hearts. Tissue inhibitor of metalloproteinase (TIMP)3 and TIMP4 messenger RNA and protein showed the greatest reduction in no-LVAD hearts. Basement membrane proteins exhibited less severe disarray of laminin and fibronectin-1 in LVAD-supported hearts. The rise in matricellular protein, osteopontin, was suppressed in LVAD hearts, whereas secreted protein, acidic, cysteine-rich (SPARC) levels was unaffected by LVAD. Mechanical unloading of the failing DCM hearts can restore the fibrillar ECM and the basement membrane, contributing toward improved clinical outcomes. However, persistent elevation of matricellular proteins such as SPARC could contribute to the relapse of failing hearts on removal of LVAD support.

  17. Metabolic rates of ATP transfer through creatine kinase (CK Flux) predict clinical heart failure events and death.

    PubMed

    Bottomley, Paul A; Panjrath, Gurusher S; Lai, Shenghan; Hirsch, Glenn A; Wu, Katherine; Najjar, Samer S; Steinberg, Angela; Gerstenblith, Gary; Weiss, Robert G

    2013-12-11

    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.

  18. 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.

  19. Contraceptive failure in China.

    PubMed

    Wang, Duolao

    2002-09-01

    This study examines patterns and differentials of contraceptive failure rates by method and characteristics of users, using the Chinese Two-per-Thousand Fertility Survey data. The results show that contraceptive failure rates for modern methods including sterilization are some of the highest in the world. The first year failure rates are 4.2% for male sterilization, 0.7% for female sterilization, 10.3% for IUD, 14.5% for pill, and 19.0% for condom. There are also some differentials in contraceptive failure rates by users' sociodemographic and fertility characteristics. Contraceptive failure rate declines with women's age for all reversible methods. Rural women have higher sterilization, IUD, and condom contraceptive failure rates than urban women. Women with two or more children have a higher failure rate for sterilization methods but have lower failure rates for other methods.

  20. Comparative normal/failing rat myocardium cell membrane chromatographic analysis system for screening specific components that counteract doxorubicin-induced heart failure from Acontium carmichaeli.

    PubMed

    Chen, Xiaofei; Cao, Yan; Zhang, Hai; Zhu, Zhenyu; Liu, Min; Liu, Haibin; Ding, Xuan; Hong, Zhanying; Li, Wuhong; Lv, Diya; Wang, Lirong; Zhuo, Xianyi; Zhang, Junping; Xie, Xiang-Qun; Chai, Yifeng

    2014-05-20

    Cell membrane chromatography (CMC) derived from pathological tissues is ideal for screening specific components acting on specific diseases from complex medicines owing to the maximum simulation of in vivo drug-receptor interactions. However, there are no pathological tissue-derived CMC models that have ever been developed, as well as no visualized affinity comparison of potential active components between normal and pathological CMC columns. In this study, a novel comparative normal/failing rat myocardium CMC analysis system based on online column selection and comprehensive two-dimensional (2D) chromatography/monolithic column/time-of-flight mass spectrometry was developed for parallel comparison of the chromatographic behaviors on both normal and pathological CMC columns, as well as rapid screening of the specific therapeutic agents that counteract doxorubicin (DOX)-induced heart failure from Acontium carmichaeli (Fuzi). In total, 16 potential active alkaloid components with similar structures in Fuzi were retained on both normal and failing myocardium CMC models. Most of them had obvious decreases of affinities on failing myocardium CMC compared with normal CMC model except for four components, talatizamine (TALA), 14-acetyl-TALA, hetisine, and 14-benzoylneoline. One compound TALA with the highest affinity was isolated for further in vitro pharmacodynamic validation and target identification to validate the screen results. Voltage-dependent K(+) channel was confirmed as a binding target of TALA and 14-acetyl-TALA with high affinities. The online high throughput comparative CMC analysis method is suitable for screening specific active components from herbal medicines by increasing the specificity of screened results and can also be applied to other biological chromatography models.

  1. 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…

  2. Down-regulation of progesterone receptor membrane component 1 (PGRMC1) in peripheral nucleated blood cells associated with premature ovarian failure (POF) and polycystic ovary syndrome (PCOS)

    PubMed Central

    2010-01-01

    Background Progesterone receptor membrane component 1 (PGRMC1) is a member of a progesterone-binding complex implicated in female reproduction. We aimed i) to determine the natural expression of PGRMC1 in peripheral nucleated blood cells throughout the menstrual cycle and ii) to investigate any association between PGRMC1 levels in leukocytes and conditions characterized by reduced fertility. Methods We analyzed PGRMC1 expression in peripheral leukocytes from 15 healthy cycling women over four weeks. Additionally, we determined PGRMC1 levels in samples from patients with premature ovarian failure (POF) and polycystic ovary syndrome (PCOS) as well as in healthy postmenopausal women and male controls. The levels of PGRMC1 protein in nucleated peripheral blood cells were quantified by Western blot analysis. Results PGRMC1 levels did not vary significantly throughout the menstrual cycle. We observed a significant down-regulation of PGRMC1 in postmenopausal women and in patients with premature ovarian failure (POF) and polycystic ovary syndrome (PCOS) when compared to early follicular phase of healthy women. Conclusion This study suggests that reduced levels of PGRMC1 in peripheral leukocytes are associated with perturbed ovulatory function. PMID:20537145

  3. 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

  4. 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.

  5. CFD modelling of most probable bubble nucleation rate from binary mixture with estimation of components' mole fraction in critical cluster

    NASA Astrophysics Data System (ADS)

    Hong, Ban Zhen; Keong, Lau Kok; Shariff, Azmi Mohd

    2016-05-01

    The employment of different mathematical models to address specifically for the bubble nucleation rates of water vapour and dissolved air molecules is essential as the physics for them to form bubble nuclei is different. The available methods to calculate bubble nucleation rate in binary mixture such as density functional theory are complicated to be coupled along with computational fluid dynamics (CFD) approach. In addition, effect of dissolved gas concentration was neglected in most study for the prediction of bubble nucleation rates. The most probable bubble nucleation rate for the water vapour and dissolved air mixture in a 2D quasi-stable flow across a cavitating nozzle in current work was estimated via the statistical mean of all possible bubble nucleation rates of the mixture (different mole fractions of water vapour and dissolved air) and the corresponding number of molecules in critical cluster. Theoretically, the bubble nucleation rate is greatly dependent on components' mole fraction in a critical cluster. Hence, the dissolved gas concentration effect was included in current work. Besides, the possible bubble nucleation rates were predicted based on the calculated number of molecules required to form a critical cluster. The estimation of components' mole fraction in critical cluster for water vapour and dissolved air mixture was obtained by coupling the enhanced classical nucleation theory and CFD approach. In addition, the distribution of bubble nuclei of water vapour and dissolved air mixture could be predicted via the utilisation of population balance model.

  6. 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.

  7. 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 ...

  8. Efficacy of hyaluronan-rich transfer medium on implantation and pregnancy rates in fresh and frozen-thawed blastocyst transfers in Korean women with previous implantation failure

    PubMed Central

    Chun, Sungwook; Seo, Jung Eun; Rim, Yun Jeung; Joo, Jae Hong; Lee, Yong Chan

    2016-01-01

    Objective To evaluate the effect of hyaluronan-rich transfer medium on pregnancy and implantation rates in fresh and frozen-thawed embryo transfers in Korean women with previous implantation failure. Methods This retrospective study included 283 blastocyst transfers in patients with previous embryo transfer failure at a private fertility clinic. In the study group (n=88), blastocyst transfers were performed using an hyaluronan-rich transfer medium prior to transfer, whereas blastocyst transfers without any treatment served as controls (n=195). According to the type of transfer (fresh elective or frozen-thawed), all the blastocyst transfers were divided into two study and two control groups. Results The patient's mean age, serum anti-Müllerian hormone level, causes of infertility, embryo quality, and the number of transferred embryos were comparable between the study and control groups. There were no significant differences in clinical pregnancy rate (45.5% vs. 43.1%), implantation rate (28.9% vs. 28.8%), and clinical abortion rate (10.0% vs. 8.3%) between the two groups, and these findings were not changed after subgroup analysis according to the type of transfer. Conclusion The use of hyaluronan-rich transfer medium in the blastocyst transfer does not appear to have any significant effect on the implantation and pregnancy rates in patients with previous implantation failure. PMID:27200310

  9. 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.

  10. High rate of per oral mecillinam treatment failure in community-acquired urinary tract infections caused by ESBL-producing Escherichia coli.

    PubMed

    Søraas, Arne; Sundsfjord, Arnfinn; Jørgensen, Silje Bakken; Liestøl, Knut; Jenum, Pål A

    2014-01-01

    A population-based study was performed to investigate the efficacy of mecillinam treatment of community-acquired urinary tract infections (CA-UTI) caused by extended-spectrum β-lactamase (ESBL) producing Escherichia coli. The study was conducted in South-Eastern Norway. Data from patients with CA-UTI caused by ESBL-producing and non-producing (random controls) E. coli were collected through interviews, questionnaires, medical records and the Norwegian Prescription Database. Treatment failure was defined as a new antibiotic prescription appropriate for UTI prescribed within two weeks after the initial antimicrobial therapy. Multivariable logistic regression analysis was performed to identify treatment agents and patient- or bacterial traits associated with treatment failure. A total of 343 patients (mean age 59) were included, of which 158 (46%) were treated with mecillinam. Eighty-one patients (24%, mean age 54) had infections caused by ESBL producing E. coli, and 41 of these patients (51%) received mecillinam as the primary treatment. Mecillinam treatment failure was observed in 18 (44%) of patients infected by ESBL-producing strains and in 16 (14%) of patients with a CA-UTI caused by ESBL non-producing strains. Multivariable analysis showed that ESBL status (odds ratio (OR) 3.2, 95% confidence interval (CI) 1.3-7.8, p = 0.009) and increased MIC of mecillinam (OR 2.0 for each doubling value of MIC, CI 1.4-3.0, p<0.001) were independently associated with mecillinam treatment failure. This study showed a high rate of mecillinam treatment failure in CA-UTIs caused by ESBL producing E. coli. The high failure rate could not be explained by the increased MIC of mecillinam alone. Further studies addressing the use of mecillinam against ESBL-producing E. coli, with emphasis on optimal dosing and combination therapy with β-lactamase inhibitors, are warranted.

  11. 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.

  12. 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.

  13. Reduced memory multi-layer multi-component rate allocation for JPEG2000

    NASA Astrophysics Data System (ADS)

    Kulkarni, Prajit; Bilgin, Ali; Marcellin, Michael W.; Dagher, Joseph C.; Flohr, Thomas; Rountree, Janet

    2005-03-01

    Remote sensing images are often multispectral in nature and are acquired by on-board sensors in a "push-broom" fashion. These images are compressed and transmitted to ground stations for further analysis. Since they are extremely large, buffering all acquired data before encoding requires huge amounts of memory and introduces latency. Incremental compression schemes work on small chunks of raw data as soon as they are acquired and help reduce buffer memory requirements. However, incremental processing leads to large variations in quality across the reconstructed image. We propose two "leaky bucket" rate control algorithms that can be employed for incrementally compressing hyperspectral images using JPEG2000. Both schemes perform rate control using the fine granularity afforded by JPEG2000. The proposed algorithms have low memory requirements and enable SNR scalability through the use of quality layers. Experiments show that the proposed schemes provide significant reduction in quality variation with no loss in mean overall PSNR performance.

  14. A quantitative investigation of the influence with the components of the CMP alkali slurry on the polishing rate

    NASA Astrophysics Data System (ADS)

    Shiyan, Fan; Enhai, Liu; Jun, Zhang; Yuling, Liu; Lei, Wang; Kai, Lin; Ming, Sun; Lukui, Shi

    2015-09-01

    The influence of the components of an alkali polishing slurry and the mutual influences on the Cu polishing rate were investigated by a CMP polishing rate prediction model established with a modified artificial neural network based on the artificial bee colony algorithm. The quantitative method of sensitivity analysis was employed to fulfill the purpose of quantizing the influence on the polishing rate. The result of the analysis indicates that under certain CMP conditions, the Cu polishing rate was controlled by the silica abrasives, the FA/O chelating agent, the surfactant and the oxidant agent in the polishing slurry. Such factors showed the different sensitivity coefficients with 0.78, 0.53, 0.29 and 0.19 respectively on all the sample points. The mutual influence between the FA/O chelating agent and the oxidant agent on the polishing rate seemed obviously strongest when the proportion of them was 2 to 7, with the global sensitivity coefficients between 5 to 9; the mutual influence of silica abrasives and oxidant on the polishing rate was greater as the proportion of the above additives was beyond 5, with the global sensitivity coefficients between 2.5 and 6; the mutual influence of the surfactant and oxidant on the polishing rate was not obvious, with global sensitivity coefficients less than 3. Thus, it provides a kind of effective method for quantitating the influence with the components of the CMP alkali slurry on the polishing rate. Project supported by the Special Project Items No. 2 in National Long-Term Technology Development Plan, China (No. 2009ZX02308) and the Natural Science Foundation of Hebei Province, China (No. F2013202104).

  15. Neutron activation analysis of ceramic tiles and its component and radon exhalation rate.

    PubMed

    El-Shershaby, A; Sroor, A; Ahmed, F; Abdel-Haleem, A S; Abdel, Z

    2004-01-01

    The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis(NAA) technique. The samples and standard were irradiated with reactor for 4 h (in the Second Research Egyptian Reactor(Et-RR-2)) with thermal neutron flux 5.9 x 10(13) n/(cm2 x s). The gamma-ray spectra obtained were measured for several times by means of the hyper pure germanium detection system(HPGe). Also a solid state nuclear track detector(SSNTD) CR-39, was used to measure the emanation rate of radon for these samples. The radium concentrations were found to vary from 0.39-3.59 ppm and the emanation rates were found to vary from (0.728-5.688) x 10(-4) kg/(m2 x s). The elemental analysis of the ceramic tiles and ceramic composites have a great importance in assigning the physical properties and in turn the quality of the material.

  16. Experimental investigation of the failure envelope of unidirectional carbon-epoxy composite under high strain rate transverse and off-axis tensile loading

    NASA Astrophysics Data System (ADS)

    Kuhn, Peter; Ploeckl, Marina; Koerber, Hannes

    2015-09-01

    The mechanical response of the carbon-epoxy material system HexPly IM7-8552 was investigated under transverse tension and combined transverse tension / in-plane shear loading at quasi-static and dynamic strain rates. The dynamic tests of the transverse tension and off-axis tension specimens were carried out on a split-Hopkinson tension bar system, while the quasi-static reference tests were performed on a standard electro-mechanical testing machine. Digital image correlation was used for data reduction at both strain rate regimes. For the high rate tests, the strain rate in loading direction was adjusted to reach approximately the same strain rate value in the fracture plane for each specimen. The measured axial strengths were transformed from the global coordinate system into the combined transverse tension-shear stress space of the material coordinate system and compared with the Puck Mode A criterion for inter-fibre failure. A good correlation between the experimental data and the predicted failure envelopes was found for both investigated strain rate regimes.

  17. Effects of thoracic and fine PM and their components on heart rate and pulmonary function in COPD patients.

    PubMed

    Hsu, Sha O-I; Ito, Kazuhiko; Lippmann, Morton

    2011-01-01

    Population-based personal exposures to particulate matter (PM) and personal-ambient relationships of PM and component concentrations for outpatients with COPD and/or asthma were investigated in New York City (NYC) and Seattle for thoracic PM (PM(10)) and fine PM (PM(2.5)). Measurements of outdoor, indoor, and personal PM(10) and PM(2.5) concentrations were made concurrently for 12-consecutive days at 24 patients' residences. Filters were analyzed for elemental components, using XRF and black carbon (BC), by reflectance. Daily morning and evening measurements of heart rate (HR) and blood oxygen saturation (SpO(2)) by pulse oximeter, and forced expiratory volume in 1 s (FEV(1)) and peak expiratory flowrate (PEF) by spirometry were also measured, and symptom data were collected. Central monitoring site, outdoor, indoor, and personal concentration-response relationships of PM(2.5), PM(10-2.5), and their components were examined using mixed-effect models. The relatively small sample size of the study limited the interpretation of results, but of the PM chemical components examined, only nickel concentrations showed consistent associations, and only with HR in the NYC COPD patients. PMID:21407271

  18. Modelling the failure behaviour of wind turbines

    NASA Astrophysics Data System (ADS)

    Faulstich, S.; Berkhout, V.; Mayer, J.; Siebenlist, D.

    2016-09-01

    Modelling the failure behaviour of wind turbines is an essential part of offshore wind farm simulation software as it leads to optimized decision making when specifying the necessary resources for the operation and maintenance of wind farms. In order to optimize O&M strategies, a thorough understanding of a wind turbine's failure behaviour is vital and is therefore being developed at Fraunhofer IWES. Within this article, first the failure models of existing offshore O&M tools are presented to show the state of the art and strengths and weaknesses of the respective models are briefly discussed. Then a conceptual framework for modelling different failure mechanisms of wind turbines is being presented. This framework takes into account the different wind turbine subsystems and structures as well as the failure modes of a component by applying several influencing factors representing wear and break failure mechanisms. A failure function is being set up for the rotor blade as exemplary component and simulation results have been compared to a constant failure rate and to empirical wind turbine fleet data as a reference. The comparison and the breakdown of specific failure categories demonstrate the overall plausibility of the model.

  19. Failure Rate of Direct High-Viscosity Glass-Ionomer Versus Hybrid Resin Composite Restorations in Posterior Permanent Teeth - a Systematic Review

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Purpose Traditionally, resin composite restorations are claimed by reviews of the dental literature as being superior to glass-ionomer fillings in terms of restoration failures in posterior permanent teeth. The aim of this systematic review is to answer the clinical question, whether conventional high-viscosity glass-ionomer restorations, in patients with single and/or multi-surface cavities in posterior permanent teeth, have indeed a higher failure rate than direct hybrid resin composite restorations. Methods Eight databases were searched until December 02, 2013. Trials were assessed for bias risks, in-between datasets heterogeneity and statistical sample size power. Effects sizes were computed and statistically compared. A total of 55 citations were identified through systematic literature search. From these, 46 were excluded. No trials related to high-viscosity glass-ionomers versus resin composite restorations for direct head-to-head comparison were found. Three trials related to high-viscosity glass-ionomers versus amalgam and three trials related to resin composite versus amalgam restorations could be included for adjusted indirect comparison, only. Results The available evidence suggests no difference in the failure rates between both types of restoration beyond the play of chance, is limited by lack of head-to-head comparisons and an insufficient number of trials, as well as by high bias and in-between-dataset heterogeneity risk. The current clinical evidence needs to be regarded as too poor in order to justify superiority claims regarding the failure rates of both restoration types. Sufficiently large-sized, parallel-group, randomised control trials with high internal validity are needed, in order to justify any clinically meaningful judgment to this topic. PMID:26962372

  20. 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 Central

    Urbanek, Bożena; Ruta, Jan; Kudryński, Krzysztof; Ptaszyński, Paweł; Klimczak, Artur; Wranicz, Jerzy Krzysztof

    2016-01-01

    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/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. PMID:27305349

  1. 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

    2016-01-01

    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. PMID:27305349

  2. Comparative Treatment Failure Rates of Respiratory Fluoroquinolones or β-Lactam + Macrolide Versus β-Lactam Alone in the Treatment for Community-Acquired Pneumonia in Adult Outpatients

    PubMed Central

    Lee, Meng-Tse Gabriel; Lee, Shih-Hao; Chang, Shy-Shin; Chan, Ya-Lan; Pang, Laura; Hsu, Sue-Ming; Lee, Chien-Chang

    2015-01-01

    Abstract No comparative effectiveness study has been conducted for the following 3 antibiotics: respiratory fluoroquinolone, β-lactam, and β-lactam + advanced macrolide. To gain insights into the real-world clinical effectiveness of these antibiotics for community-acquired pneumonia in adult outpatients, our study investigated the treatment failure rates in 2 million representative participants from the National Health Informatics Project (NHIP) of Taiwan. A new-user cohort design was used to follow NHIP participants from January 2000 until December 2009. Treatment failure was defined by either one of the following events: a second antibiotic prescription, hospitalization due to CAP, an emergency department visit with a diagnosis of CAP, or 30-day nonaccident-related mortality. From 2006 to 2009, we identified 9256 newly diagnosed CAP outpatients, 1602 of whom were prescribed levofloxacin, 2100 were prescribed moxifloxacin, 5049 were prescribed β-lactam alone, and 505 were prescribed advanced macrolide + β-lactam. Compared with the β-lactam-based regimen, the propensity score-matched odds ratio for composite treatment failure was 0.81 (95% CI, 0.67–0.97) for moxifloxacin, 1.10 (95% CI, 0.90–1.35) for levofloxacin, and 0.95 (95% CI, 0.67–1.35) for macrolide +β-lactam. Moxifloxacin was associated with lower treatment failure rates compared with β-lactam alone, or levofloxacin in Taiwanese CAP outpatients. However, due to inherent limitations in our claims database, more randomized controlled trials are required before coming to a conclusion on which antibiotic is more effective for Taiwanese CAP outpatients. More population-based comparative effectiveness studies are also encouraged and should be considered as an integral piece of evidence in local CAP treatment guidelines. PMID:26426664

  3. Wind Turbine Failures - Tackling current Problems in Failure Data Analysis

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    The wind industry has been growing significantly over the past decades, resulting in a remarkable increase in installed wind power capacity. Turbine technologies are rapidly evolving in terms of complexity and size, and there is an urgent need for cost effective operation and maintenance (O&M) strategies. Especially unplanned downtime represents one of the main cost drivers of a modern wind farm. Here, reliability and failure prediction models can enable operators to apply preventive O&M strategies rather than corrective actions. In order to develop these models, the failure rates and downtimes of wind turbine (WT) components have to be understood profoundly. This paper is focused on tackling three of the main issues related to WT failure analyses. These are, the non-uniform data treatment, the scarcity of available failure analyses, and the lack of investigation on alternative data sources. For this, a modernised form of an existing WT taxonomy is introduced. Additionally, an extensive analysis of historical failure and downtime data of more than 4300 turbines is presented. Finally, the possibilities to encounter the lack of available failure data by complementing historical databases with Supervisory Control and Data Acquisition (SCADA) alarms are evaluated.

  4. Oscillatory behavior of ventricular action potential duration in heart failure patients at respiratory rate and low frequency

    PubMed Central

    Hanson, Ben; Child, Nick; Van Duijvenboden, Stefan; Orini, Michele; Chen, Zhong; Coronel, Ruben; Rinaldi, Christopher A.; Gill, Jaspal S.; Gill, Jaswinder S.; Taggart, Peter

    2014-01-01

    Oscillations of arterial pressure occur spontaneously at a frequency of approximately 0.1 Hz coupled with synchronous oscillations of sympathetic nerve activity (“Mayer waves”). This study investigated the extent to which corresponding oscillations may occur in ventricular action potential duration (APD). Fourteen ambulatory (outpatient) heart failure patients with biventricular pacing devices were studied while seated upright watching movie clips to maintain arousal. Activation recovery intervals (ARI) as a measure of ventricular APD were obtained from unipolar electrograms recorded from the LV epicardial pacing lead during steady state RV pacing from the device. Arterial blood pressure was measured non-invasively (Finapress) and respiration monitored. Oscillations were quantified using time frequency and coherence analysis. Oscillatory behavior of ARI at the respiratory frequency was observed in all subjects. The magnitude of the ARI variation ranged from 2.2 to 6.9 ms (mean 5.0 ms). Coherence analysis showed a correlation with respiratory oscillation for an average of 43% of the recording time at a significance level of p < 0.05. Oscillations in systolic blood pressure in the Mayer wave frequency range were observed in all subjects for whom blood pressure was recorded (n = 13). ARI oscillation in the Mayer wave frequency range was observed in 6/13 subjects (46%) over a range of 2.9 to 9.2 ms. Coherence with Mayer waves at the p < 0.05 significance level was present for an average of 29% of the recording time. In ambulatory patients with heart failure during enhanced mental arousal, left ventricular epicardial APD (ARI) oscillated at the respiratory frequency (approximately 0.25 Hz). In 6 patients (46%) APD oscillated at the slower Mayer wave frequency (approximately 0.1 Hz). These findings may be important in understanding sympathetic activity-related arrhythmogenesis. PMID:25389408

  5. Heart rate variability parameters of myxomatous mitral valve disease in dogs with and without heart failure obtained using 24-hour Holter electrocardiography.

    PubMed

    Oliveira, M S; Muzzi, R A L; Araújo, R B; Muzzi, L A L; Ferreira, D F; Nogueira, R; Silva, E F

    2012-06-16

    Time-domain heart rate variability (HRV) parameters and the correlation between echocardiography and Holter examinations in dogs with myxomatous mitral valve disease (MMVD) were determined. Holter examination was also performed at different time frames: an entire 24-hour period, a four-hour period during sleep, and a four-hour period while awake. Ten healthy (control group) and 28 MMVD dogs, 15 with and 13 without heart failure, were evaluated. The SDANN (sd of the mean normal RR intervals for all five-minute segments during 24-hour Holter) and pNN(50) (percentage of differences between adjacent normal RR intervals that are >50 ms computed over 24-hour Holter) variables were significantly lower in the dogs with MMVD heart failure. The differences in HRV between the groups were only detected during the 24-hour evaluation period (P<0.05). There were high correlations (canonical analysis) between Holter and echocardiography examinations when considering pNN(50), SDANN, and LA/AO (left atrial to aortic root ratio) (r=0.92; P<0.05), indicating that both are important in evaluating MMVD dogs. SDANN and pNN(50) are measures of parasympathetic control of the heart, and thus, it is possible to infer that the MMVD dogs exhibit parasympathetic withdrawal during the development of heart failure.

  6. Human sperm devoid of germinal angiotensin-converting enzyme is responsible for total fertilization failure and lower fertilization rates by conventional in vitro fertilization.

    PubMed

    Li, Le-Jun; Zhang, Feng-Bin; Liu, Shu-Yuan; Tian, Yong-Hong; Le, Fang; Wang, Li-Ya; Lou, Hang-Ying; Xu, Xiang-Rong; Huang, He-Feng; Jin, Fan

    2014-06-01

    In conventional in vitro fertilization (IVF), complete failure of fertilization occurs in 5% to 15% of treatments. Although the causes may be unclear, sperm defects appear to be the major contributor. However, a convincing test is not yet available that can predict the risk of fertilization failure. In this study, we found that germinal angiotensin-converting enzyme (gACE) (also called testicular ACE) was undetectable in sperm from patients who had total fertilization failure (TFF) and lower fertilization rates (LFRs) by IVF based on Western blot and indirect immunofluorescence analyses. Additionally, almost all of the patients without gACE on sperm (23 of 25) manifested a TT genotype of the rs4316 single-nucleotide polymorphism of ACE. Overall, our results indicate that the absence of gACE expression is responsible for TFF and LFRs by IVF. The rs4316 polymorphism of ACE might be associated with infertility in those patients. We conclude that sperm lacking gACE may be recognized before commencing IVF and that the patients may be directed instead to consider intracytoplasmic sperm injection.

  7. Excellent Local Control Rates and Distinctive Patterns of Failure in Myxoid Liposarcoma Treated With Conservation Surgery and Radiotherapy

    SciTech Connect

    Guadagnolo, B. Ashleigh Zagars, Gunar K.; Ballo, Matthew T.; Patel, Shreyaskumar R.; Lewis, Valerae O.; Benjamin, Robert S.; Pollock, Raphael E.

    2008-03-01

    Purpose: To evaluate the local control rates and patterns of metastatic relapse in patients with localized myxoid liposarcoma treated with conservation surgery and radiotherapy (RT). Patients and Methods: Between 1960 and 2003, 127 patients with non-metastatic myxoid liposarcoma were treated with conservation surgery and RT at our institution. The median patient age was 39 years (range, 14-79 years). Of the 127 patients, 46% underwent preoperative RT (median dose, 50 Gy) and 54% underwent postoperative RT (median dose, 60 Gy). Also, 28% received doxorubicin-based chemotherapy as a part of their treatment. Results: The median follow-up was 9.1 years. The overall survival rate at 5 and 10 years was 87% and 79%, respectively. The corresponding disease-free survival rates were 81% and 73%. The local control rate at {>=}5 years was 97%. The actuarial rate of distant metastases at 5 and 10 years was 15% and 24%, respectively. Of the 27 patients who developed distant metastases, 48% did so in the retroperitoneum, 22% in other extrapulmonary soft tissues, 22% in the lung, 15% in bone, and 4% in the liver. Conclusion: The results of our study have shown that RT and conservation surgery for localized myxoid liposarcoma provide excellent local control. Distant metastatic relapse tended to occur in the retroperitoneum and other nonpulmonary soft tissues. Therefore, staging and surveillance imaging should include the abdomen and pelvis, as well as the thorax, for patients with localized myxoid liposarcoma.

  8. A placebo-controlled study examining the effect of allopurinol on heart rate variability and dysrhythmia counts in chronic heart failure

    PubMed Central

    Shehab, Abdullah M A; Butler, Robert; MacFadyen, Robert J; Struthers, Allan D

    2001-01-01

    Aims Allopurinol improves endothelial function in chronic heart failure by reducing oxidative stress. We wished to explore if such an effect would attenuate autonomic dysfunction in CHF in line with many other effective therapies in CHF. Methods We performed a prospective, randomized, double-blind cross-over study in 16 patients with NYHA Class II-IV chronic heart failure (mean age 67 ± 10 years, 13 male, comparing allopurinol (2 months) at a daily dose of 300 mg (if creatinine < 150 µmol l−1) or 100 mg (if creatinine > 150 µmol l−1) with matched placebo. Mean heart rate and dysrhythmia counts were recorded from 24 h Holter tapes at monthly intervals for 6 months. We assessed autonomic function using standard time domain heart rate variability parameters (HRV): SDNN, SDANN, SDNN index, rMSSD and TI. Results Allopurinol had no significant effect on heart rate variability compared with placebo; the results are expressed as a difference in means ± s.d. with 95% confidence interval (CI) between allopurinol and placebo: SDNN mean=6.5 ± 4.8 ms, P = 0.18 and 95% CI (−3.7, 17); TI mean=−2.1 ± 1.4, P = 0.16 and 95% CI (−5.2, 0.8); SDANN mean=−2.8 ± 7 ms, P = 0.68 and 95% CI (−18, 12); SDNNi mean=2 ± 6.6, P = 0.7 and 95% CI (−12, 16); RMSSD mean=−0.9 ± 2, P = 0.68 and 95% CI (−5.6, 3.7). For mean heart rate the corresponding results were 0.9 ± 1.4, P = 0.5 and 95% CI (−2, 3.8). Log 24 h ventricular ectopic counts (VEC) were 0.032 ± 0.37, P = 0.7 and 95% CI (−0.1, 0.2). Patient compliance with study medication was good since allopurinol showed its expected effect of reducing plasma uric acid (P < 0.001). Conclusions Allopurinol at doses, which are known to reduce oxidative stress appear to have no significant effect on resting autonomic tone, as indicated by time domain heart rate variability or on dysrhythmia count in stable heart failure patients. PMID:11318768

  9. Gravity field and solar component of the precession rate and nutation coefficients of Comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Lhotka, C.; Reimond, S.; Souchay, J.; Baur, O.

    2016-02-01

    The aim of this study is first to determine the gravity field of the comet 67P/Churyumov-Gerasimenko and second to derive the solar component of the precession rate and nutation coefficients of the spin-axis of the comet nucleus, i.e. without the direct, usually larger, effect of outgassing. The gravity field and related moments of inertia are obtained from two polyhedra, which are provided by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) and NAVigation CAMera (NAVCAM) experiments on Rosetta, and are based on the assumption of uniform density for the comet nucleus. We also calculate the forced precession rate as well as the nutation coefficients on the basis of Kinoshita's theory of rotation of the rigid Earth and adapted it to be able to indirectly include the effect of outgassing on the rotational parameters. The second degree denormalized Stokes coefficients of comet 67P/C-G turn out to be (bracketed numbers refer to second shape model) C20 ≃ -6.74 [-7.93] × 10-2, C22 ≃ 2.60 [2.71] × 10-2, consistent with normalized principal moments of inertia A/MR2 ≃ 0.13 [0.11], B/MR2 ≃ 0.23 [0.22], with polar moment c = C/MR2 ≃ 0.25, depending on the choice of the polyhedron model. The obliquity between the rotation axis and the mean orbit normal is ε ≃ 52°, and the precession rate only due to solar torques becomes dot{ψ }in [20,30] arcsec yr^{-1}. Oscillations in longitude caused by the gravitational pull of the Sun turn out to be of the order of Δψ ≃ 1 arcmin, and oscillations in obliquity can be estimated to be of the order of Δε ≃ 0.5 arcmin.

  10. Estimation of calcium and phosphorus content in growing and finishing pigs: whole empty body components and relative accretion rates.

    PubMed

    Pettey, L A; Cromwell, G L; Jang, Y D; Lindemann, M D

    2015-01-01

    Two comparative serial-slaughter experiments were conducted to determine whole empty body (WEB) composition and accretion rates of Ca and P in 18 to 109 kg BW pigs to provide information for modeling of these nutrients for growth. Both studies were conducted with 5 sets of 5 littermate barrows which were allotted to 5 slaughter groups in each study (Exp. 1: 18, 27, 36, 45, and 54 kg BW; Exp. 2: 36, 54, 73, 91, and 109 kg BW). Pigs were fed corn-soybean meal-based diets fortified with minerals and vitamins in 2 dietary phases in Exp. 1 (Phase 1: 18 to 36 kg BW; Phase 2: 36 to 54 kg BW) and 3 dietary phases in Exp. 2 (Phase 2: 36 to 54 kg BW; Phase 3: 54 to 78 kg BW; and Phase 4: 78 to 109 kg BW). At the predetermined BW, pigs were slaughtered and separated into body components of hair, hooves, blood, head, viscera, and carcass. The carcass was split along the dorsal midline and the left carcass side was ground for chemical analysis. Whole empty body weight averaged 93.6% and 94.0% of live BW in Exp. 1 and Exp. 2, respectively. As WEB weight increased in both experiments, the percentage carcass of the WEB linearly (P < 0.05) increased, the percentage viscera linearly (P < 0.05) decreased, and the mass (g) of N, ash, Ca, and P in the WEB increased linearly (R(2) = 0.98). The concentration (g/kg) of P in the WEB of 18 to 54 kg pigs increased from 4.30 to 4.57 (linear; P < 0.05) and for Ca increased from 5.13 to 5.66 (linear; P < 0.05). In Exp. 2, P concentration was not related to WEB weight and Ca concentration increased quadratically (P < 0.05). The relative accretion rate of N to P was 1.00 (R(2) = 0.99) in the pigs from 18 to 54 kg. In conclusion, these results indicate that compositional changes as BW increases are strongly related to P retention and that the quantification of WEB P and relationships of WEB P to other chemical components in the body may be useful for modeling purposes in growing and finishing pigs.

  11. Estimation of calcium and phosphorus content in growing and finishing pigs: whole empty body components and relative accretion rates.

    PubMed

    Pettey, L A; Cromwell, G L; Jang, Y D; Lindemann, M D

    2015-01-01

    Two comparative serial-slaughter experiments were conducted to determine whole empty body (WEB) composition and accretion rates of Ca and P in 18 to 109 kg BW pigs to provide information for modeling of these nutrients for growth. Both studies were conducted with 5 sets of 5 littermate barrows which were allotted to 5 slaughter groups in each study (Exp. 1: 18, 27, 36, 45, and 54 kg BW; Exp. 2: 36, 54, 73, 91, and 109 kg BW). Pigs were fed corn-soybean meal-based diets fortified with minerals and vitamins in 2 dietary phases in Exp. 1 (Phase 1: 18 to 36 kg BW; Phase 2: 36 to 54 kg BW) and 3 dietary phases in Exp. 2 (Phase 2: 36 to 54 kg BW; Phase 3: 54 to 78 kg BW; and Phase 4: 78 to 109 kg BW). At the predetermined BW, pigs were slaughtered and separated into body components of hair, hooves, blood, head, viscera, and carcass. The carcass was split along the dorsal midline and the left carcass side was ground for chemical analysis. Whole empty body weight averaged 93.6% and 94.0% of live BW in Exp. 1 and Exp. 2, respectively. As WEB weight increased in both experiments, the percentage carcass of the WEB linearly (P < 0.05) increased, the percentage viscera linearly (P < 0.05) decreased, and the mass (g) of N, ash, Ca, and P in the WEB increased linearly (R(2) = 0.98). The concentration (g/kg) of P in the WEB of 18 to 54 kg pigs increased from 4.30 to 4.57 (linear; P < 0.05) and for Ca increased from 5.13 to 5.66 (linear; P < 0.05). In Exp. 2, P concentration was not related to WEB weight and Ca concentration increased quadratically (P < 0.05). The relative accretion rate of N to P was 1.00 (R(2) = 0.99) in the pigs from 18 to 54 kg. In conclusion, these results indicate that compositional changes as BW increases are strongly related to P retention and that the quantification of WEB P and relationships of WEB P to other chemical components in the body may be useful for modeling purposes in growing and finishing pigs. PMID:25568364

  12. Relation of Elevated Heart Rate in Patients With Heart Failure With Reduced Ejection Fraction to One-Year Outcomes and Costs.

    PubMed

    DeVore, Adam D; Schulte, Phillip J; Mentz, Robert J; Hardy, N Chantelle; Kelly, Jacob P; Velazquez, Eric J; Maya, Juan F; Kielhorn, Adrian; Patel, Harshali K; Reed, Shelby D; Hernandez, Adrian F

    2016-03-15

    There are limited data describing outcomes associated with an elevated heart rate in patients with heart failure with reduced ejection fraction (HFrEF) in routine clinical practice. We identified patients with HFrEF at Duke University Hospital undergoing echocardiograms and heart rate assessments without paced rhythms or atrial fibrillation. Outcomes (all-cause mortality or hospitalization and medical costs per day alive) were assessed using electronic medical records, hospital cost accounting data, and national death records. Patients were stratified by heart rate (<70 and ≥70 beats/min) and compared using generalized linear models specified with gamma error distributions and log links for costs and proportional hazard models for mortality/hospitalization. Of 722 eligible patients, 582 patients (81%) were treated with β blockers. The median heart rate was 81 beats/min (25th and 75th percentiles 69 to 96) and 527 patients (73%) had a heart rate ≥70 beats/min. After multivariate adjustment, a heart rate ≥70 beats/min was associated with increased 1-year all-cause mortality or hospitalization, hazard ratio 1.37 (95% CI 1.07 to 1.75) and increased medical costs per day alive, cost ratio 2.03 (95% CI 1.53 to 2.69). In conclusion, at a large tertiary care center, despite broad use of β blockers, a heart rate ≥70 beats/min was observed in 73% of patients with HFrEF and associated with worse 1-year outcomes and increased direct medical costs per day alive. PMID:26805662

  13. Validation of RNAi Silencing Efficiency Using Gene Array Data shows 18.5% Failure Rate across 429 Independent Experiments

    PubMed Central

    Munkácsy, Gyöngyi; Sztupinszki, Zsófia; Herman, Péter; Bán, Bence; Pénzváltó, Zsófia; Szarvas, Nóra; Győrffy, Balázs

    2016-01-01

    No independent cross-validation of success rate for studies utilizing small interfering RNA (siRNA) for gene silencing has been completed before. To assess the influence of experimental parameters like cell line, transfection technique, validation method, and type of control, we have to validate these in a large set of studies. We utilized gene chip data published for siRNA experiments to assess success rate and to compare methods used in these experiments. We searched NCBI GEO for samples with whole transcriptome analysis before and after gene silencing and evaluated the efficiency for the target and off-target genes using the array-based expression data. Wilcoxon signed-rank test was used to assess silencing efficacy and Kruskal–Wallis tests and Spearman rank correlation were used to evaluate study parameters. All together 1,643 samples representing 429 experiments published in 207 studies were evaluated. The fold change (FC) of down-regulation of the target gene was above 0.7 in 18.5% and was above 0.5 in 38.7% of experiments. Silencing efficiency was lowest in MCF7 and highest in SW480 cells (FC = 0.59 and FC = 0.30, respectively, P = 9.3E−06). Studies utilizing Western blot for validation performed better than those with quantitative polymerase chain reaction (qPCR) or microarray (FC = 0.43, FC = 0.47, and FC = 0.55, respectively, P = 2.8E−04). There was no correlation between type of control, transfection method, publication year, and silencing efficiency. Although gene silencing is a robust feature successfully cross-validated in the majority of experiments, efficiency remained insufficient in a significant proportion of studies. Selection of cell line model and validation method had the highest influence on silencing proficiency. PMID:27673562

  14. Rates and determinants of progression to graft failure in kidney allograft recipients with de novo donor-specific antibody.

    PubMed

    Wiebe, C; Gibson, I W; Blydt-Hansen, T D; Pochinco, D; Birk, P E; Ho, J; Karpinski, M; Goldberg, A; Storsley, L; Rush, D N; Nickerson, P W

    2015-11-01

    Understanding rates and determinants of clinical pathologic progression for recipients with de novo donor-specific antibody (dnDSA), especially subclinical dnDSA, may identify surrogate endpoints and inform clinical trial design. A consecutive cohort of 508 renal transplant recipients (n = 64 with dnDSA) was studied. Recipients (n = 388) without dnDSA or dysfunction had an eGFR decline of -0.65 mL/min/1.73 m(2) /year. In recipients with dnDSA, the rate eGFR decline was significantly increased prior to dnDSA onset (-2.89 vs. -0.65 mL/min/1.73 m(2) /year, p < 0.0001) and accelerated post-dnDSA (-3.63 vs. -2.89 mL/min/1.73 m(2) /year, p < 0.0001), suggesting that dnDSA is both a marker and contributor to ongoing alloimmunity. Time to 50% post-dnDSA graft loss was longer in recipients with subclinical versus a clinical dnDSA phenotype (8.3 vs. 3.3 years, p < 0.0001). Analysis of 1091 allograft biopsies found that dnDSA and time independently predicted chronic glomerulopathy (cg), but not interstitial fibrosis and tubular atrophy (IFTA). Early T cell-mediated rejection, nonadherence, and time were multivariate predictors of IFTA. Independent risk factors for post-dnDSA graft survival available prior to, or at the time of, dnDSA detection were delayed graft function, nonadherence, dnDSA mean fluorescence intensity sum score, tubulitis, and cg. Ultimately, dnDSA is part of a continuum of mixed alloimmune-mediated injury, which requires solutions targeting T and B cells.

  15. Validation of RNAi Silencing Efficiency Using Gene Array Data shows 18.5% Failure Rate across 429 Independent Experiments.

    PubMed

    Munkácsy, Gyöngyi; Sztupinszki, Zsófia; Herman, Péter; Bán, Bence; Pénzváltó, Zsófia; Szarvas, Nóra; Győrffy, Balázs

    2016-01-01

    No independent cross-validation of success rate for studies utilizing small interfering RNA (siRNA) for gene silencing has been completed before. To assess the influence of experimental parameters like cell line, transfection technique, validation method, and type of control, we have to validate these in a large set of studies. We utilized gene chip data published for siRNA experiments to assess success rate and to compare methods used in these experiments. We searched NCBI GEO for samples with whole transcriptome analysis before and after gene silencing and evaluated the efficiency for the target and off-target genes using the array-based expression data. Wilcoxon signed-rank test was used to assess silencing efficacy and Kruskal-Wallis tests and Spearman rank correlation were used to evaluate study parameters. All together 1,643 samples representing 429 experiments published in 207 studies were evaluated. The fold change (FC) of down-regulation of the target gene was above 0.7 in 18.5% and was above 0.5 in 38.7% of experiments. Silencing efficiency was lowest in MCF7 and highest in SW480 cells (FC = 0.59 and FC = 0.30, respectively, P = 9.3E-06). Studies utilizing Western blot for validation performed better than those with quantitative polymerase chain reaction (qPCR) or microarray (FC = 0.43, FC = 0.47, and FC = 0.55, respectively, P = 2.8E-04). There was no correlation between type of control, transfection method, publication year, and silencing efficiency. Although gene silencing is a robust feature successfully cross-validated in the majority of experiments, efficiency remained insufficient in a significant proportion of studies. Selection of cell line model and validation method had the highest influence on silencing proficiency. PMID:27673562

  16. Kidney Failure

    MedlinePlus

    ... if You Have Kidney Disease Kidney Failure Expand Dialysis Kidney Transplant Preparing for Kidney Failure Treatment Choosing Not to Treat with Dialysis or Transplant Paying for Kidney Failure Treatment Contact ...

  17. Multi-scale defect interactions in high-rate brittle material failure. Part I: Model formulation and application to ALON

    NASA Astrophysics Data System (ADS)

    Tonge, Andrew L.; Ramesh, K. T.

    2016-01-01

    Within this two part series we develop a new material model for ceramic protection materials to provide an interface between microstructural parameters and bulk continuum behavior to provide guidance for materials design activities. Part I of this series focuses on the model formulation that captures the strength variability and strain rate sensitivity of brittle materials and presents a statistical approach to assigning the local flaw distribution within a specimen. The material model incorporates a Mie-Grüneisen equation of state, micromechanics based damage growth, granular flow and dilatation of the highly damaged material, and pore compaction for the porosity introduced by granular flow. To provide initial qualitative validation and illustrate the usefulness of the model, we use the model to investigate Edge on Impact experiments (Strassburger, 2004) on Aluminum Oxynitride (AlON), and discuss the interactions of multiple mechanisms during such an impact event. Part II of this series is focused on additional qualitative validation and using the model to suggest material design directions for boron carbide.

  18. Rates of Reconstruction Failure in Patients Undergoing Immediate Reconstruction With Tissue Expanders and/or Implants and Postmastectomy Radiation Therapy

    SciTech Connect

    Fowble, Barbara; Park, Catherine; Wang, Frederick; Peled, Anne; Alvarado, Michael; Ewing, Cheryl; Esserman, Laura; Foster, Robert; Sbitany, Hani; Hanlon, Alex

    2015-07-01

    Objectives: 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). Methods and Materials: 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. Results: 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. Conclusions: RFs in patients receiving PMRT were lowered with total TE/I coverage at the time of radiation by avoiding inframammary fold incisions and

  19. Reliability analysis based on the losses from failures.

    PubMed

    Todinov, M T

    2006-04-01

    The conventional reliability analysis is based on the premise that increasing the reliability of a system will decrease the losses from failures. On the basis of counterexamples, it is demonstrated that this is valid only if all failures are associated with the same losses. In case of failures associated with different losses, a system with larger reliability is not necessarily characterized by smaller losses from failures. Consequently, a theoretical framework and models are proposed for a reliability analysis, linking reliability and the losses from failures. Equations related to the distributions of the potential losses from failure have been derived. It is argued that the classical risk equation only estimates the average value of the potential losses from failure and does not provide insight into the variability associated with the potential losses. Equations have also been derived for determining the potential and the expected losses from failures for nonrepairable and repairable systems with components arranged in series, with arbitrary life distributions. The equations are also valid for systems/components with multiple mutually exclusive failure modes. The expected losses given failure is a linear combination of the expected losses from failure associated with the separate failure modes scaled by the conditional probabilities with which the failure modes initiate failure. On this basis, an efficient method for simplifying complex reliability block diagrams has been developed. Branches of components arranged in series whose failures are mutually exclusive can be reduced to single components with equivalent hazard rate, downtime, and expected costs associated with intervention and repair. A model for estimating the expected losses from early-life failures has also been developed. For a specified time interval, the expected losses from early-life failures are a sum of the products of the expected number of failures in the specified time intervals covering the

  20. Progressive failure of structures

    NASA Technical Reports Server (NTRS)

    Khozeimeh, K.; Toridis, G. T. G.; Zanganeh, S. E.

    1978-01-01

    A procedure is presented for determining the nonlinear behavior of structures subjected to extreme loading and the possibility of development of potential for progressive failure. The methodology takes into account the effect of both material and geometric nonlinearities. At a given stage of analysis, the individual components of the structure are checked against predetermined failure criteria. Subsequently, the failing components are removed and the modified structure is analyzed for overall failure. Examples, obtained from a computer program based on the proposed procedure, showing the applicability of the method are presented.

  1. Modelling early failures in Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Navard, Sharon E.

    1993-01-01

    A major problem encountered in planning for Space Station Freedom is the amount of maintenance that will be required. To predict the failure rates of components and systems aboard Space Station Freedom, the logical approach is to use data obtained from previously flown spacecraft. In order to determine the mechanisms that are driving the failures, models can be proposed, and then checked to see if they adequately fit the observed failure data obtained from a large variety of satellites. For this particular study, failure data and truncation times were available for satellites launched between 1976 and 1984; no data past 1984 was available. The study was limited to electrical subsystems and assemblies, which were studied to determine if they followed a model resulting from a mixture of exponential distributions.

  2. A rate- and state-dependent friction model to describe the seasonal motion of slow-moving earthflows and quantify their potential for catastrophic failure

    NASA Astrophysics Data System (ADS)

    Handwerger, A. L.; Rempel, A. W.; Roering, J. J.; Hilley, G. E.; Skarbek, R. M.

    2014-12-01

    Slow-moving earthflows regularly exhibit seasonal velocity patterns driven by transient perturbations in effective normal stress that alter the frictional resistance along the sliding surface. These annual velocity patterns are ubiquitous in slow-moving landslides throughout the world, with individual landslides often displaying complex spatial patterns of acceleration that can vary from year to year. Here, we model landslide motion using a rate- and state-dependent frictional treatment that incorporates variations in effective normal stress and material properties, including both velocity-weakening (VW) and velocity-strengthening (VS) patches, along the sliding surface. We calculate changes in effective stress by allowing rainfall-induced changes in pore-water pressure to diffuse vertically from the ground surface to the landslide base. We then solve for changes in frictional strength and velocity along a 1D slip surface that extends the length of the landslide. Model parameters are calibrated using measurements from laboratory tests, field instruments, and satellite InSAR. Our model is able to produce seasonal variations in sliding rate that mimic the patterns commonly displayed by these slope failures. We use our model to identify the conditions under which these slides can transition from non-catastrophic motion to catastrophic failure. We find that non-catastrophic motion occurs if the landslides are comprised of entirely VS material or if their spatial dimensions do not exceed a critical nucleation length, which is determined by the ratio of VW to VS material and the effective stress. Furthermore, this modeling framework suggests that landslides that exhibit spatially varying motion (i.e. consisting of an ensemble of smaller slip patches) may be less likely to fail catastrophically when compared to landslides that exhibit spatially uniform motion if differences in the timing of motion along the landslide reflect the presence of temporary slip barriers (i

  3. Disparate Rates of Utilization and Progression to Combined Heart Failure and Chronic Obstructive Pulmonary Disease among Asians and Pacific Islanders in Hawai'i.

    PubMed

    Davis, James; Tam, Elizabeth; Taira, Deborah

    2016-08-01

    The objectives of the study were to compare ethnic differences in the rates of emergency department (ED) visits and hospitalizations, and to examine ethnic differences in how quickly patients with either chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF) developed both diseases. A large health plan in Hawai.i provided administrative data (2007 to 2010) on patients of Native Hawaiian, Japanese, Chinese, Filipino, and White race/ethnicity. The study found distinct patterns of health risks among the multi-ethnic population of patients with COPD, CHF, or both conditions. Native Hawaiians had the highest rates of ED visits and hospitalizations. Japanese, the largest ethnic group and relatively low health risks, were selected as the reference population. In adjusted regression models, Filipino patients with CHF developed COPD the most rapidly; 71% faster than Japanese patients. Compared to Japanese, Native Hawaiians with COPD transitioned to CHF 68% faster. The study highlights ethnic disparities in adverse events and disease progression in patients with COPD and CHF, with important implications for clinical practice. Health care providers may want to inform patients of ways to mitigate the risks. PMID:27563499

  4. Disparate Rates of Utilization and Progression to Combined Heart Failure and Chronic Obstructive Pulmonary Disease among Asians and Pacific Islanders in Hawai‘i

    PubMed Central

    Tam, Elizabeth; Taira, Deborah

    2016-01-01

    The objectives of the study were to compare ethnic differences in the rates of emergency department (ED) visits and hospitalizations, and to examine ethnic differences in how quickly patients with either chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF) developed both diseases. A large health plan in Hawai.i provided administrative data (2007 to 2010) on patients of Native Hawaiian, Japanese, Chinese, Filipino, and White race/ethnicity. The study found distinct patterns of health risks among the multi-ethnic population of patients with COPD, CHF, or both conditions. Native Hawaiians had the highest rates of ED visits and hospitalizations. Japanese, the largest ethnic group and relatively low health risks, were selected as the reference population. In adjusted regression models, Filipino patients with CHF developed COPD the most rapidly; 71% faster than Japanese patients. Compared to Japanese, Native Hawaiians with COPD transitioned to CHF 68% faster. The study highlights ethnic disparities in adverse events and disease progression in patients with COPD and CHF, with important implications for clinical practice. Health care providers may want to inform patients of ways to mitigate the risks. PMID:27563499

  5. ACDOS1: a computer code to calculate dose rates from neutron activation of neutral beamlines and other fusion-reactor components

    SciTech Connect

    Keney, G.S.

    1981-08-01

    A computer code has been written to calculate neutron induced activation of neutral-beam injector components and the corresponding dose rates as a function of geometry, component composition, and time after shutdown. The code, ACDOS1, was written in FORTRAN IV to calculate both activity and dose rates for up to 30 target nuclides and 50 neutron groups. Sufficient versatility has also been incorporated into the code to make it applicable to a variety of general activation problems due to neutrons of energy less than 20 MeV.

  6. Nonalcoholic Fatty Liver Disease Is Associated With Higher 1-year All-Cause Rehospitalization Rates in Patients Admitted for Acute Heart Failure

    PubMed Central

    Valbusa, Filippo; Bonapace, Stefano; Grillo, Cristina; Scala, Luca; Chiampan, Andrea; Rossi, Andrea; Zoppini, Giacomo; Lonardo, Amedeo; Arcaro, Guido; Byrne, Christopher D.; Targher, Giovanni

    2016-01-01

    Abstract Repeat hospitalization due to acute heart failure (HF) is a global public health problem that markedly impacts on health resource use. Identifying novel predictors of rehospitalization would help physicians to determine the optimal postdischarge plan for preventing HF rehospitalization. Nonalcoholic fatty liver disease (NAFLD) is an emerging risk factor for many heart diseases, including HF. We assessed whether NAFLD at hospital admission predicts 1-year all-cause rehospitalization in patients with acute HF. We enrolled all patients consecutively admitted for acute HF to our General Medicine Division, from January 2013 to April 2014, after excluding patients with acute myocardial infarction, severe heart valve diseases, malignancy, known liver diseases, and those with volume overload related to extracardiac causes. NAFLD was diagnosed by ultrasonography and exclusion of competing etiologies. The primary outcome of the study was the 1-year all-cause rehospitalization rate. Among the 107 patients enrolled in the study, the cumulative rehospitalization rate was 12.1% at 1 month, 25.2% at 3 months, 29.9% at 6 months, and 38.3% at 1 year. Patients with NAFLD had markedly higher 1-year rehospitalization rates than those without NAFLD (58% vs 21% at 1 y; P < 0.001 by the log-rank test). Cox regression analysis revealed that NAFLD was associated with a 5.5-fold increased risk of rehospitalization (adjusted hazard ratio 5.56, 95% confidence interval 2.46–12.1, P < 0.001) after adjustment for multiple HF risk factors and potential confounders. In conclusion, NAFLD was independently associated with higher 1-year rehospitalization in patients hospitalized for acute HF. PMID:26886619

  7. Failure detection and identification

    NASA Technical Reports Server (NTRS)

    Massoumnia, Mohammad-Ali; Verghese, George C.; Willsky, Alan S.

    1989-01-01

    Using the geometric concept of an unobservability subspace, a solution is given to the problem of detecting and identifying control system component failures in linear, time-invariant systems. Conditions are developed for the existence of a causal, linear, time-invariant processor that can detect and uniquely identify a component failure, first for the case where components can fail simultaneously, and then for the case where they fail only one at a time. Explicit design algorithms are provided when these conditions are satisfied. In addition to time-domain solvability conditions, frequency-domain interpretations of the results are given, and connections are drawn with results already available in the literature.

  8. The failure of earthquake failure models

    USGS Publications Warehouse

    Gomberg, J.

    2001-01-01

    In this study I show that simple heuristic models and numerical calculations suggest that an entire class of commonly invoked models of earthquake failure processes cannot explain triggering of seismicity by transient or "dynamic" stress changes, such as stress changes associated with passing seismic waves. The models of this class have the common feature that the physical property characterizing failure increases at an accelerating rate when a fault is loaded (stressed) at a constant rate. Examples include models that invoke rate state friction or subcritical crack growth, in which the properties characterizing failure are slip or crack length, respectively. Failure occurs when the rate at which these grow accelerates to values exceeding some critical threshold. These accelerating failure models do not predict the finite durations of dynamically triggered earthquake sequences (e.g., at aftershock or remote distances). Some of the failure models belonging to this class have been used to explain static stress triggering of aftershocks. This may imply that the physical processes underlying dynamic triggering differs or that currently applied models of static triggering require modification. If the former is the case, we might appeal to physical mechanisms relying on oscillatory deformations such as compaction of saturated fault gouge leading to pore pressure increase, or cyclic fatigue. However, if dynamic and static triggering mechanisms differ, one still needs to ask why static triggering models that neglect these dynamic mechanisms appear to explain many observations. If the static and dynamic triggering mechanisms are the same, perhaps assumptions about accelerating failure and/or that triggering advances the failure times of a population of inevitable earthquakes are incorrect.

  9. Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module

    SciTech Connect

    Lee C. Cadwallader

    2007-08-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with “generic” component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance.

  10. Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module

    SciTech Connect

    Lee C. Cadwallader

    2010-06-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with “generic” component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance.

  11. Preliminary Failure Modes and Effects Analysis of the US Massive Gas Injection Disruption Mitigation System Design

    SciTech Connect

    Lee C. Cadwallader

    2013-10-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a candidate design for the ITER Disruption Mitigation System. This candidate is the Massive Gas Injection System that provides machine protection in a plasma disruption event. The FMEA was quantified with “generic” component failure rate data as well as some data calculated from operating facilities, and the failure events were ranked for their criticality to system operation.

  12. Respiratory Failure

    MedlinePlus

    Respiratory failure happens when not enough oxygen passes from your lungs into your blood. Your body's organs, ... brain, need oxygen-rich blood to work well. Respiratory failure also can happen if your lungs can' ...

  13. 12 May 2008 M = 7.9 Wenchuan, China, earthquake calculated to increase failure stress and seismicity rate on three major fault systems

    USGS Publications Warehouse

    Toda, S.; Lin, J.; Meghraoui, M.; Stein, R.S.

    2008-01-01

    The Wenchuan earthquake on the Longmen Shan fault zone devastated cities of Sichuan, claiming at least 69,000 lives. We calculate that the earthquake also brought the Xianshuihe, Kunlun and Min Jiang faults 150-400 km from the mainshock rupture in the eastern Tibetan Plateau 0.2-0.5 bars closer to Coulomb failure. Because some portions of these stressed faults have not ruptured in more than a century, the earthquake could trigger or hasten additional M > 7 earthquakes, potentially subjecting regions from Kangding to Daofu and Maqin to Rangtag to strong shaking. We use the calculated stress changes and the observed background seismicity to forecast the rate and distribution of damaging shocks. The earthquake probability in the region is estimated to be 57-71% for M ??? 6 shocks during the next decade, and 8-12% for M ??? 7 shocks. These are up to twice the probabilities for the decade before the Wenchuan earthquake struck. Copyright 2008 by the American Geophysical Union.

  14. Predicting survival in heart failure case and control subjects by use of fully automated methods for deriving nonlinear and conventional indices of heart rate dynamics

    NASA Technical Reports Server (NTRS)

    Ho, K. K.; Moody, G. B.; Peng, C. K.; Mietus, J. E.; Larson, M. G.; Levy, D.; Goldberger, A. L.

    1997-01-01

    BACKGROUND: Despite much recent interest in quantification of heart rate variability (HRV), the prognostic value of conventional measures of HRV and of newer indices based on nonlinear dynamics is not universally accepted. METHODS AND RESULTS: We have designed algorithms for analyzing ambulatory ECG recordings and measuring HRV without human intervention, using robust methods for obtaining time-domain measures (mean and SD of heart rate), frequency-domain measures (power in the bands of 0.001 to 0.01 Hz [VLF], 0.01 to 0.15 Hz [LF], and 0.15 to 0.5 Hz [HF] and total spectral power [TP] over all three of these bands), and measures based on nonlinear dynamics (approximate entropy [ApEn], a measure of complexity, and detrended fluctuation analysis [DFA], a measure of long-term correlations). The study population consisted of chronic congestive heart failure (CHF) case patients and sex- and age-matched control subjects in the Framingham Heart Study. After exclusion of technically inadequate studies and those with atrial fibrillation, we used these algorithms to study HRV in 2-hour ambulatory ECG recordings of 69 participants (mean age, 71.7+/-8.1 years). By use of separate Cox proportional-hazards models, the conventional measures SD (P<.01), LF (P<.01), VLF (P<.05), and TP (P<.01) and the nonlinear measure DFA (P<.05) were predictors of survival over a mean follow-up period of 1.9 years; other measures, including ApEn (P>.3), were not. In multivariable models, DFA was of borderline predictive significance (P=.06) after adjustment for the diagnosis of CHF and SD. CONCLUSIONS: These results demonstrate that HRV analysis of ambulatory ECG recordings based on fully automated methods can have prognostic value in a population-based study and that nonlinear HRV indices may contribute prognostic value to complement traditional HRV measures.

  15. Adjunct low-molecular-weight heparin to improve live birth rate after recurrent implantation failure: a systematic review and meta-analysis.

    PubMed

    Potdar, Neelam; Gelbaya, Tarek A; Konje, Justin C; Nardo, Luciano G

    2013-01-01

    BACKGROUND Poor fertility outcomes in women with recurrent implantation failure (≥ RIF) present significant challenges in assisted reproduction, and various adjuncts, including heparin, are used for potential improvement in pregnancy rates. We performed this systematic review and meta-analysis to evaluate the effect of low-molecular-weight heparin (LMWH) on live birth rates (LBRs) and implantation rates (IRs) in women with RIF and undergoing IVF. METHODS Studies comparing LMWH versus control/placebo in women with RIF were searched for on MEDLINE, EMBASE, Cochrane Library, conference proceedings and databases for registered and ongoing trials (1980-2012). Statistical analysis was performed using Review Manager 5.1. The main outcome measure was LBR per woman. RESULTS Two randomized controlled trials (RCTs) and one quasi-randomized trial met the inclusion criteria. One study included women with at least one thrombophilia ( Qublan et al., 2008) and two studies included women with unexplained RIF ( Urman et al., 2009; Berker et al., 2011). Pooled risk ratios in women with ≥ 3 RIF (N = 245) showed a significant improvement in the LBR (risk ratio (RR) = 1.79, 95% confidence interval (CI) = 1.10-2.90, P = 0.02) and a reduction in the miscarriage rate (RR = 0.22, 95% CI = 0.06-0.78, P = 0.02) with LMWH compared with controls. The IR for ≥ 3 RIF (N = 674) showed a non-significant trend toward improvement (RR = 1.73, 95% CI 0.98-3.03, P = 0.06) with LMWH. However, the beneficial effect of LMWH was not significant when only studies with unexplained RIF were pooled. The summary analysis for the numbers needed to be treated with LMWH showed that approximately eight women would require treatment to achieve one extra live birth. CONCLUSIONS In women with ≥3 RIF, the use of adjunct LMWH significantly improves LBR by 79% compared with the control group; however, this is to be considered with caution, since the overall number of participants in the studies was small. Further

  16. Generalized energy failure criterion.

    PubMed

    Qu, R T; Zhang, Z J; Zhang, P; Liu, Z Q; Zhang, Z F

    2016-01-01

    Discovering a generalized criterion that can predict the mechanical failure of various different structural materials is one of ultimate goals for scientists in both material and mechanics communities. Since the first study on the failure criterion of materials by Galileo, about three centuries have passed. Now we eventually find the "generalized energy criterion", as presented here, which appears to be one universal law for various different kinds of materials. The validity of the energy criterion for quantitatively predicting the failure is experimentally confirmed using a metallic glass. The generalized energy criterion reveals the competition and interaction between shear and cleavage, the two fundamental inherent failure mechanisms, and thus provides new physical insights into the failure prediction of materials and structural components. PMID:26996781

  17. Generalized energy failure criterion

    PubMed Central

    Qu, R. T.; Zhang, Z. J.; Zhang, P.; Liu, Z. Q.; Zhang, Z. F.

    2016-01-01

    Discovering a generalized criterion that can predict the mechanical failure of various different structural materials is one of ultimate goals for scientists in both material and mechanics communities. Since the first study on the failure criterion of materials by Galileo, about three centuries have passed. Now we eventually find the “generalized energy criterion”, as presented here, which appears to be one universal law for various different kinds of materials. The validity of the energy criterion for quantitatively predicting the failure is experimentally confirmed using a metallic glass. The generalized energy criterion reveals the competition and interaction between shear and cleavage, the two fundamental inherent failure mechanisms, and thus provides new physical insights into the failure prediction of materials and structural components. PMID:26996781

  18. Being on sick leave due to heart failure: self-rated health, encounters with healthcare professionals and social insurance officers and self-estimated ability to return to work.

    PubMed

    Nordgren, Lena; Söderlund, Anne

    2015-01-01

    Younger people with heart failure often experience poor self-rated health. Furthermore, poor self-rated health is associated with long-term sick leave and disability pension. Socio-demographic factors affect the ability to return to work. However, little is known about people on sick leave due to heart failure. The aim of this study was to investigate associations between self-rated health, mood, socio-demographic factors, sick leave compensation, encounters with healthcare professionals and social insurance officers and self-estimated ability to return to work, for people on sick leave due to heart failure. This population-based investigation had a cross-sectional design. Data were collected in Sweden in 2012 from two official registries and from a postal questionnaire. In total, 590 subjects, aged 23-67, responded (response rate 45.8%). Descriptive statistics, correlation analyses (Spearman bivariate analysis) and logistic regression analyses were used to investigate associations. Poor self-rated health was strongly associated with full sick leave compensation (OR = 4.1, p < .001). Compared self-rated health was moderately associated with low income (OR =  .6, p =  .003). Good self-rated health was strongly associated with positive encounters with healthcare professionals (OR = 3.0, p =  .022) and to the impact of positive encounters with healthcare professionals on self-estimated ability to return to work (OR = 3.3, p < .001). People with heart failure are sicklisted for long periods of time and to a great extent receive disability pension. Not being able to work imposes reduced quality of life. Positive encounters with healthcare professionals and social insurance officers can be supportive when people with heart failure struggle to remain in working life.

  19. Failure to restore sagittal tibiotalar alignment in total ankle arthroplasty: Its relationship to the axis of the tibia and the positioning of the talar component.

    PubMed

    Cho, J; Yi, Y; Ahn, T K; Choi, H J; Park, C H; Chun, D I; Lee, J S; Lee, W C

    2015-11-01

    The purpose of this study was to evaluate the change in sagittal tibiotalar alignment after total ankle arthroplasty (TAA) for osteoarthritis and to investigate factors affecting the restoration of alignment. This retrospective study included 119 patients (120 ankles) who underwent three component TAA using the Hintegra prosthesis. A total of 63 ankles had anterior displacement of the talus before surgery (group A), 49 had alignment in the normal range (group B), and eight had posterior displacement of the talus (group C). Ankles in group A were further sub-divided into those in whom normal alignment was restored following TAA (41 ankles) and those with persistent displacement (22 ankles). Radiographic and clinical results were assessed. Pre-operatively, the alignment in group A was significantly more varus than that in group B, and the posterior slope of the tibial plafond was greater (p < 0.01 in both cases). The posterior slope of the tibial component was strongly associated with restoration of alignment: ankles in which the alignment was restored had significantly less posterior slope (p < 0.001). An anteriorly translated talus was restored to a normal position after TAA in most patients. We suggest that surgeons performing TAA using the Hintegra prosthesis should aim to insert the tibial component at close to 90° relative to the axis of the tibia, hence reducing posterior soft-tissue tension and allowing restoration of normal tibiotalar alignment following surgery.

  20. The PLASTID DIVISION1 and 2 components of the chloroplast division machinery determine the rate of chloroplast division in land plant cell differentiation.

    PubMed

    Okazaki, Kumiko; Kabeya, Yukihiro; Suzuki, Kenji; Mori, Toshiyuki; Ichikawa, Takanari; Matsui, Minami; Nakanishi, Hiromitsu; Miyagishima, Shin-Ya

    2009-06-01

    In most algae, the chloroplast division rate is held constant to maintain the proper number of chloroplasts per cell. By contrast, land plants evolved cell and chloroplast differentiation systems in which the size and number of chloroplasts change along with their respective cellular function by regulation of the division rate. Here, we show that PLASTID DIVISION (PDV) proteins, land plant-specific components of the division apparatus, determine the rate of chloroplast division. Overexpression of PDV proteins in the angiosperm Arabidopsis thaliana and the moss Physcomitrella patens increased the number but decreased the size of chloroplasts; reduction of PDV levels resulted in the opposite effect. The level of PDV proteins, but not other division components, decreased during leaf development, during which the chloroplast division rate also decreased. Exogenous cytokinins or overexpression of the cytokinin-responsive transcription factor CYTOKININ RESPONSE FACTOR2 increased the chloroplast division rate, where PDV proteins, but not other components of the division apparatus, were upregulated. These results suggest that the integration of PDV proteins into the division machinery enabled land plant cells to change chloroplast size and number in accord with the fate of cell differentiation.

  1. Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates on Mars

    NASA Technical Reports Server (NTRS)

    Schuerger, A. C.; Kern, R. G.

    2003-01-01

    In order to minimize the forward contamination of Mars, spacecraft are assembled under clean-room conditions that often require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival by protecting spores from sterilizing agents, including UV irradiation on the surface of Mars. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

  2. Design of Critical Components

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Zaretsky, Erwin V.

    2001-01-01

    Critical component design is based on minimizing product failures that results in loss of life. Potential catastrophic failures are reduced to secondary failures where components removed for cause or operating time in the system. Issues of liability and cost of component removal become of paramount importance. Deterministic design with factors of safety and probabilistic design address but lack the essential characteristics for the design of critical components. In deterministic design and fabrication there are heuristic rules and safety factors developed over time for large sets of structural/material components. These factors did not come without cost. Many designs failed and many rules (codes) have standing committees to oversee their proper usage and enforcement. In probabilistic design, not only are failures a given, the failures are calculated; an element of risk is assumed based on empirical failure data for large classes of component operations. Failure of a class of components can be predicted, yet one can not predict when a specific component will fail. The analogy is to the life insurance industry where very careful statistics are book-kept on classes of individuals. For a specific class, life span can be predicted within statistical limits, yet life-span of a specific element of that class can not be predicted.

  3. Failure mechanisms of fibrin-based surgical tissue adhesives

    NASA Astrophysics Data System (ADS)

    Sierra, David Hugh

    A series of studies was performed to investigate the potential impact of heterogeneity in the matrix of multiple-component fibrin-based tissue adhesives upon their mechanical and biomechanical properties both in vivo and in vitro. Investigations into the failure mechanisms by stereological techniques demonstrated that heterogeneity could be measured quantitatively and that the variation in heterogeneity could be altered both by the means of component mixing and delivery and by the formulation of the sealant. Ex vivo tensile adhesive strength was found to be inversely proportional to the amount of heterogeneity. In contrast, in vivo tensile wound-closure strength was found to be relatively unaffected by the degree of heterogeneity, while in vivo parenchymal organ hemostasis in rabbits was found to be affected: greater heterogeneity appeared to correlate with an increase in hemostasis time and amount of sealant necessary to effect hemostasis. Tensile testing of the bulk sealant showed that mechanical parameters were proportional to fibrin concentration and that the physical characteristics of the failure supported a ductile mechanism. Strain hardening as a function of percentage of strain, and strain rate was observed for both concentrations, and syneresis was observed at low strain rates for the lower fibrin concentration. Blister testing demonstrated that burst pressure and failure energy were proportional to fibrin concentration and decreased with increasing flow rate. Higher fibrin concentration demonstrated predominately compact morphology debonds with cohesive failure loci, demonstrating shear or viscous failure in a viscoelastic rubbery adhesive. The lower fibrin concentration sealant exhibited predominately fractal morphology debonds with cohesive failure loci, supporting an elastoviscous material condition. The failure mechanism for these was hypothesized and shown to be flow-induced ductile fracture. Based on these findings, the failure mechanism was

  4. Separating arterial and venous-related components of photoplethysmographic signals for accurate extraction of oxygen saturation and respiratory rate.

    PubMed

    Yousefi, Rasoul; Nourani, Mehrdad

    2015-05-01

    We propose an algorithm for separating arterial and venous-related signals using second-order statistics of red and infrared signals in a blind source separation technique. The separated arterial signal is used to compute accurate arterial oxygen saturation. We have also introduced an algorithm for extracting the respiratory pattern from the extracted venous-related signal. In addition to real-time monitoring, respiratory rate is also extracted. Our experimental results from multiple subjects show that the proposed separation technique is extremely useful for extracting accurate arterial oxygen saturation and respiratory rate. Specifically, the breathing rate is extracted with average root mean square deviation of 1.89 and average mean difference of -0.69. PMID:25055387

  5. Evidence for a respiratory component, similar to mammalian respiratory sinus arrhythmia, in the heart rate variability signal from the rattlesnake, Crotalus durissus terrificus.

    PubMed

    Campbell, Hamish A; Leite, Cleo A C; Wang, Tobias; Skals, Marianne; Abe, Augusto S; Egginton, Stuart; Rantin, F Tadeu; Bishop, Charles M; Taylor, Edwin W

    2006-07-01

    Autonomic control of heart rate variability and the central location of vagal preganglionic neurones (VPN) were examined in the rattlesnake (Crotalus durissus terrificus), in order to determine whether respiratory sinus arrhythmia (RSA) occurred in a similar manner to that described for mammals. Resting ECG signals were recorded in undisturbed snakes using miniature datalogging devices, and the presence of oscillations in heart rate (fh) was assessed by power spectral analysis (PSA). This mathematical technique provides a graphical output that enables the estimation of cardiac autonomic control by measuring periodic changes in the heart beat interval. At fh above 19 min(-1) spectra were mainly characterised by low frequency components, reflecting mainly adrenergic tonus on the heart. By contrast, at fh below 19 min(-1) spectra typically contained high frequency components, demonstrated to be cholinergic in origin. Snakes with a fh >19 min(-1) may therefore have insufficient cholinergic tonus and/or too high an adrenergic tonus acting upon the heart for respiratory sinus arrhythmia (RSA) to develop. A parallel study monitored fh simultaneously with the intraperitoneal pressures associated with lung inflation. Snakes with a fh<19 min(-1) exhibited a high frequency (HF) peak in the power spectrum, which correlated with ventilation rate (fv). Adrenergic blockade by propranolol infusion increased the variability of the ventilation cycle, and the oscillatory component of the fh spectrum broadened accordingly. Infusion of atropine to effect cholinergic blockade abolished this HF component, confirming a role for vagal control of the heart in matching fh and fv in the rattlesnake. A neuroanatomical study of the brainstem revealed two locations for vagal preganglionic neurones (VPN). This is consistent with the suggestion that generation of ventilatory components in the heart rate variability (HRV) signal are dependent on spatially distinct loci for cardiac VPN. Therefore

  6. Dose-rate controlled energy dispersive x-ray spectroscopic mapping of the metallic components in a biohybrid nanosystem

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanyuan; Munro, Catherine J.; Olszta, Matthew J.; Edwards, Danny J.; Braunschweig, Adam B.; Knecht, Marc R.; Browning, Nigel D.

    2016-08-01

    In this work, we showcase that through precise control of the electron dose rate, state-of-the-art large solid angle energy dispersive x-ray spectroscopy mapping in aberration-corrected scanning transmission electron microscope is capable of faithful and unambiguous chemical characterization of the Pt and Pd distribution in a peptide-mediated nanosystem. This low-dose-rate recording scheme adds another dimension of flexibility to the design of elemental mapping experiments, and holds significant potential for extending its application to a wide variety of beam sensitive hybrid nanostructures.

  7. Patient-Assessed Late Toxicity Rates and Principal Component Analysis After Image-Guided Radiation Therapy for Prostate Cancer

    SciTech Connect

    Skala, Marketa; Rosewall, Tara; Dawson, Laura; Divanbeigi, Lorella; Lockwood, Gina; Thomas, Christopher; Crook, Juanita; Chung, Peter; Warde, Padraig; Catton, Charles . E-mail: charles.catton@rmp.uhn.on.ca

    2007-07-01

    Purpose: The aims of this study were to determine the incidence of patient-assessed late toxicity after high-dose, image-guided radiation therapy in a cohort of men with prostate cancer; and to correlate toxicity with conventional dosimetric parameters and rectal and bladder dose-volume histograms (DVH) reduced using principal component analysis. Methods and Materials: Toxicity questionnaires were sent to 690 men treated for localized prostate cancer to 75.6 Gy or 79.8 Gy using three-dimensional conformal radiation therapy (3DCRT) or intensity-modulated radiation therapy (IMRT) between 1997 and 2003 at the Princess Margaret Hospital. Toxicity was graded according to the modified Radiation Therapy Oncology Group (RTOG)-late effects normal tissue (LENT) scoring system. Late rectal and bladder toxicity scores were dichotomized as < Grade 2 and {>=} Grade 2, and correlated with dosimetric parameters and with the first three principal components of rectal and bladder DVHs. Results: In all, 63% of the patients completed the questionnaire. At a median follow-up of 37 months, the incidence of late rectal toxicity RTOG Grades 1, 2, and 3 was 25.2%, 2.5%, and 0.7% respectively. The incidence of late urinary toxicity RTOG Grade 1, 2, and 3 was 16.5%, 8.8%, and 0.9% respectively. Maintenance of erectile function sufficient for intercourse was reported in 68%. No dosimetric parameter analyzed, including principal component analysis reduction of DVHs, correlated with late toxicity. Conclusions: Postal questionnaire was effective for collection of patient-assessed late toxicity data. The incidence of late toxicity was low, with a lack of correlation to dosimetric parameters. We attribute this to the use of conformal techniques and daily image guidance.

  8. Novel application of multi dynamic trend analysis as a sensitive tool for detecting the effects of aging and congestive heart failure on heart rate variability.

    PubMed

    Lin, Yu-Cheng; Lin, Yu-Hsuan; Lo, Men-Tzung; Peng, Chung-Kang; Huang, Norden E; Yang, Cheryl C H; Kuo, Terry B J

    2016-02-01

    The complex fluctuations in heart rate variability (HRV) reflect cardiac autonomic modulation and are an indicator of congestive heart failure (CHF). This paper proposes a novel nonlinear approach to HRV investigation, the multi dynamic trend analysis (MDTA) method, based on the empirical mode decomposition algorithm of the Hilbert-Huang transform combined with a variable-sized sliding-window method. Electrocardiographic signal data obtained from the PhysioNet database were used. These data were from subjects with CHF (mean age = 59.4 ± 8.4), an age-matched elderly healthy control group (59.3 ± 10.6), and a healthy young group (30.3 ± 4.8); the HRVs of these subjects were processed using the MDTA method, time domain analysis, and frequency domain analysis. Among all HRV parameters, the MDTA absolute value slope (MDTS) and MDTA deviation (MDTD) exhibited the greatest area under the curve (AUC) of the receiver operating characteristics in distinguishing between the CHF group and the healthy controls (AUC = 1.000) and between the healthy elderly subject group and the young subject group (AUC = 0.834 ± 0.067 for MDTS; 0.837 ± 0.066 for MDTD). The CHF subjects presented with lower MDTA indices than those of the healthy elderly subject group. Furthermore, the healthy elderly subjects exhibited lower MDTA indices than those of the young controls. The MDTA method can adaptively and automatically identify the intrinsic fluctuation on variable temporal and spatial scales when investigating complex fluctuations in the cardiac autonomic regulation effects of aging and CHF. PMID:26931590

  9. Novel application of multi dynamic trend analysis as a sensitive tool for detecting the effects of aging and congestive heart failure on heart rate variability

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Cheng; Lin, Yu-Hsuan; Lo, Men-Tzung; Peng, Chung-Kang; Huang, Norden E.; Yang, Cheryl C. H.; Kuo, Terry B. J.

    2016-02-01

    The complex fluctuations in heart rate variability (HRV) reflect cardiac autonomic modulation and are an indicator of congestive heart failure (CHF). This paper proposes a novel nonlinear approach to HRV investigation, the multi dynamic trend analysis (MDTA) method, based on the empirical mode decomposition algorithm of the Hilbert-Huang transform combined with a variable-sized sliding-window method. Electrocardiographic signal data obtained from the PhysioNet database were used. These data were from subjects with CHF (mean age = 59.4 ± 8.4), an age-matched elderly healthy control group (59.3 ± 10.6), and a healthy young group (30.3 ± 4.8); the HRVs of these subjects were processed using the MDTA method, time domain analysis, and frequency domain analysis. Among all HRV parameters, the MDTA absolute value slope (MDTS) and MDTA deviation (MDTD) exhibited the greatest area under the curve (AUC) of the receiver operating characteristics in distinguishing between the CHF group and the healthy controls (AUC = 1.000) and between the healthy elderly subject group and the young subject group (AUC = 0.834 ± 0.067 for MDTS; 0.837 ± 0.066 for MDTD). The CHF subjects presented with lower MDTA indices than those of the healthy elderly subject group. Furthermore, the healthy elderly subjects exhibited lower MDTA indices than those of the young controls. The MDTA method can adaptively and automatically identify the intrinsic fluctuation on variable temporal and spatial scales when investigating complex fluctuations in the cardiac autonomic regulation effects of aging and CHF.

  10. Effects of Students' Multiple Intelligences on Participation Rate of Course Components in a Blended Secondary Family and Consumer Sciences Course

    ERIC Educational Resources Information Center

    Devlin, Breanne M.

    2010-01-01

    This study investigated students' learning style participation rate within a blended Family and Consumer Sciences Exploring Childhood constructivist secondary course using an exploratory quantitative approach with descriptive analysis, ANOVA testing, and contingency tables. Howard Gardner's multiple intelligence inventory was used to determine…

  11. Failure to Achieve a PSA Level {<=}1 ng/mL After Neoadjuvant LHRHA Therapy Predicts for Lower Biochemical Control Rate and Overall Survival in Localized Prostate Cancer Treated With Radiotherapy

    SciTech Connect

    Mitchell, Darren M. McAleese, Jonathan; Park, Richard M.; Stewart, David P.; Stranex, Stephen; Eakin, Ruth L.; Houston, Russell F.; O'Sullivan, Joe M.

    2007-12-01

    Purpose: To investigate whether failure to suppress the prostate-specific antigen (PSA) level to {<=}1 ng/mL after {>=}2 months of neoadjuvant luteinizing hormone-releasing hormone agonist therapy in patients scheduled to undergo external beam radiotherapy for localized prostate carcinoma is associated with reduced biochemical failure-free survival. Methods and Materials: A retrospective case note review of consecutive patients with intermediate- or high-risk localized prostate cancer treated between January 2001 and December 2002 with neoadjuvant hormonal deprivation therapy, followed by concurrent hormonal therapy and radiotherapy was performed. Patient data were divided for analysis according to whether the PSA level in Week 1 of radiotherapy was {<=}1.0 ng/mL. Biochemical failure was determined using the American Society for Therapeutic Radiology and Oncology (Phoenix) definition. Results: A total of 119 patients were identified. The PSA level after neoadjuvant hormonal deprivation therapy was {<=}1 ng/mL in 67 patients and >1 ng/mL in 52. At a median follow-up of 49 months, the 4-year actuarial biochemical failure-free survival rate was 84% vs. 60% (p = 0.0016) in favor of the patients with a PSA level after neoadjuvant hormonal deprivation therapy of {<=}1 ng/mL. The overall survival rate was 94% vs. 77.5% (p = 0.0045), and the disease-specific survival rate at 4 years was 98.5% vs. 82.5%. Conclusions: The results of our study have shown that patients with a PSA level >1 ng/mL at the beginning of external beam radiotherapy after {>=}2 months of neoadjuvant luteinizing hormone-releasing hormone agonist therapy have a significantly greater rate of biochemical failure and lower survival rate compared with those with a PSA level of {<=}1 ng/mL. Patients without adequate PSA suppression should be considered a higher risk group and considered for dose escalation or the use of novel treatments.

  12. Correlation Between Analog Noise Measurements and the Expected Bit Error Rate of a Digital Signal Propagating Through Passive Components

    NASA Technical Reports Server (NTRS)

    Warner, Joseph D.; Theofylaktos, Onoufrios

    2012-01-01

    A method of determining the bit error rate (BER) of a digital circuit from the measurement of the analog S-parameters of the circuit has been developed. The method is based on the measurement of the noise and the standard deviation of the noise in the S-parameters. Once the standard deviation and the mean of the S-parameters are known, the BER of the circuit can be calculated using the normal Gaussian function.

  13. Optimal replacement policy for a two-dissimilar-component cold standby system with different repair actions

    NASA Astrophysics Data System (ADS)

    Wang, Guan Jun; Zhang, Yuan Lin

    2016-04-01

    In this paper, a cold standby repairable system consisting of two dissimilar components and one repairman is studied. When failures occur, the repair of both component 1 and component 2 are not 'as good as new'. The consecutive operating times of component 1 after repair constitute a decreasing geometric process, while the repair times of component 1 are independent and identically distributed. For component 2, its failure is rectified by minimal repair, and the repair time is negligible. Component 1 has priority in use when both components are good. The replacement policy N is based on the failure number of component 1. Under policy N, we derive the explicit expression of the long-run average cost rate C(N) as well as the average number of repairs of component 2 before the system replaced. The optimal replacement policy N*, which minimises the long-run average cost rate C(N), is obtained theoretically. If the failure rate r(t) of component 2 is increasing, the existence and uniqueness of the optimal policy N* is also proved. Finally, a numerical example is given to validate the developed theoretical model. Some sensitivity analyses are provided to show the influence of some parameters, such as the costs for replacement and repair, and the parameters of the lifetime and repair time distributions of both components, to the optimal replacement policy N* and corresponding average cost rate C(N*).

  14. Storm-time variation of the horizontal and vertical components of the geomagnetic fields and rate of induction at different latitudes

    NASA Astrophysics Data System (ADS)

    Falayi, E. O.; Oyebanjo, O. A.; Omotosho, T. V.; Okusanya, A. A.

    2016-10-01

    The paper presents the hourly mean variation of horizontal (H) and vertical (Z) components of the geomagnetic field and the rate of induction ΔH/ΔZ at different latitudes during magnetic storm of 20 March 2001 and 1 October 2001. The results of the analysis revealed that at high latitude stations greater than 60°, the reduction in ΔH component was noticed after the noon time while other stations less than 60° experienced reduction of H in the morning time during the geomagnetic storm. Large amplitude of ΔH and ΔZ were exhibited during the daytime over the equatorial zone, the amplitude decreases from mid latitudes to the dip equator during the nighttime. The daytime enhancement of ΔH at AAE, BAN and MBO suggest the presence of a strong eastward directed current which comes under the influence of electrojet. There were strong positive and negative correlations between ring current (DR) and horizontal component of the magnetic field ΔH. The effect of rate of induction is more significant at high latitudes than lower latitudes, during the geomagnetic storm. More enhancement in rate of induction occurred at nighttime than daytime. This result may be from other sources other than the ionosphere that is magnetospheric process significantly contributes toward the variation of induction.

  15. Stochastic simulation of prokaryotic two-component signalling indicates stochasticity-induced active-state locking and growth-rate dependent bistability.

    PubMed

    Wei, Katy; Moinat, Maxim; Maarleveld, Timo R; Bruggeman, Frank J

    2014-07-29

    Signal transduction by prokaryotes almost exclusively relies on two-component systems for sensing and responding to (extracellular) signals. Here, we use stochastic models of two-component systems to better understand the impact of stochasticity on the fidelity and robustness of signal transmission, the outcome of autoregulatory gene expression and the influence of cell growth and division. We report that two-component systems are remarkably robust against copy number fluctuations of the signalling proteins they are composed of, which enhances signal transmission fidelity. Furthermore, we find that due to stochasticity these systems can get locked in an active state for extended time periods when (initially high) signal levels drop to zero. This behaviour can contribute to a bet-hedging adaptation strategy, aiding survival in fluctuating environments. Additionally, autoregulatory gene expression can cause two-component systems to become bistable at realistic parameter values. As a result, two sub-populations of cells can co-exist-active and inactive cells, which contributes to fitness in unpredictable environments. Bistability proved robust with respect to cell growth and division, and is tunable by the growth rate. In conclusion, our results indicate how single cells can cope with the inevitable stochasticity occurring in the activity of their two-component systems. They are robust to disadvantageous fluctuations that scramble signal transduction and they exploit beneficial stochasticity that generates fitness-enhancing heterogeneity across an isogenic population of cells.

  16. The AP-1 transcription factor component Fosl2 potentiates the rate of myocardial differentiation from the zebrafish second heart field.

    PubMed

    Jahangiri, Leila; Sharpe, Michka; Novikov, Natasha; González-Rosa, Juan Manuel; Borikova, Asya; Nevis, Kathleen; Paffett-Lugassy, Noelle; Zhao, Long; Adams, Meghan; Guner-Ataman, Burcu; Burns, Caroline E; Burns, C Geoffrey

    2016-01-01

    The vertebrate heart forms through successive phases of cardiomyocyte differentiation. Initially, cardiomyocytes derived from first heart field (FHF) progenitors assemble the linear heart tube. Thereafter, second heart field (SHF) progenitors differentiate into cardiomyocytes that are accreted to the poles of the heart tube over a well-defined developmental window. Although heart tube elongation deficiencies lead to life-threatening congenital heart defects, the variables controlling the initiation, rate and duration of myocardial accretion remain obscure. Here, we demonstrate that the AP-1 transcription factor, Fos-like antigen 2 (Fosl2), potentiates the rate of myocardial accretion from the zebrafish SHF. fosl2 mutants initiate accretion appropriately, but cardiomyocyte production is sluggish, resulting in a ventricular deficit coupled with an accumulation of SHF progenitors. Surprisingly, mutant embryos eventually correct the myocardial deficit by extending the accretion window. Overexpression of Fosl2 also compromises production of SHF-derived ventricular cardiomyocytes, a phenotype that is consistent with precocious depletion of the progenitor pool. Our data implicate Fosl2 in promoting the progenitor to cardiomyocyte transition and uncover the existence of regulatory mechanisms to ensure appropriate SHF-mediated cardiomyocyte contribution irrespective of embryonic stage.

  17. Data Collection for Current U.S. Wind Energy Projects: Component Costs, Financing, Operations, and Maintenance; January 2011 - September 2011

    SciTech Connect

    Martin-Tretton, M.; Reha, M.; Drunsic, M.; Keim, M.

    2012-01-01

    DNV Renewables (USA) Inc. (DNV) used an Operations and Maintenance (O&M) Cost Model to evaluate ten distinct cost scenarios encountered under variations in wind turbine component failure rates. The analysis considers: (1) a Reference Scenario using the default part failure rates within the O&M Cost Model, (2) High Failure Rate Scenarios that increase the failure rates of three major components (blades, gearboxes, and generators) individually, (3) 100% Replacement Scenarios that model full replacement of these components over a 20 year operating life, and (4) Serial Failure Scenarios that model full replacement of blades, gearboxes, and generators in years 4 to 6 of the wind project. DNV selected these scenarios to represent a broad range of possible operational experiences. Also in this report, DNV summarizes the predominant financing arrangements used to develop wind energy projects over the past several years and provides summary data on various financial metrics describing those arrangements.

  18. Evaluation Model of Life Loss Due to Dam Failure

    NASA Astrophysics Data System (ADS)

    Huang, Dongjing

    2016-04-01

    Dam failure poses a serious threat to human life, however there is still lack of systematic research on life loss which due to dam failure in China. From the perspective of protecting human life, an evaluation model for life loss caused by dam failure is put forward. The model building gets three progressive steps. Twenty dam failure cases in China are preferably chosen as the basic data, considering geographical location and construction time of dams, as well as various conditions of dam failure. Then twelve impact factors of life loss are selected, including severity degree of flood, population at risk, understanding of dam failure, warning time, evacuation condition, number of damaged buildings, water temperature, reservoir storage, dam height, dam type, break time and distance from flood area to dam. And through principal component analysis, it gets four principal components consisting of the first flood character principle component, the second warning system principle component, the third human character principle component and the fourth space-time impact principle component. After multivariate nonlinear regression and ten-fold validation in combination, the evaluation model for life loss is finally established. And the result of the proposed model is closer to the true value and better in fitting effect in comparison with the results of RESCDAM method and M. Peng method. The proposed model is not only applied to evaluate life loss and its rate under various kinds of dam failure conditions in China, but also provides reliable cause analysis and prediction approach to reduce the risk of life loss.

  19. Probabilistic Failure Assessment For Fatigue

    NASA Technical Reports Server (NTRS)

    Moore, Nicholas; Ebbeler, Donald; Newlin, Laura; Sutharshana, Sravan; Creager, Matthew

    1995-01-01

    Probabilistic Failure Assessment for Fatigue (PFAFAT) package of software utilizing probabilistic failure-assessment (PFA) methodology to model high- and low-cycle-fatigue modes of failure of structural components. Consists of nine programs. Three programs perform probabilistic fatigue analysis by means of Monte Carlo simulation. Other six used for generating random processes, characterizing fatigue-life data pertaining to materials, and processing outputs of computational simulations. Written in FORTRAN 77.

  20. The effect of age on the growth rate of tissues and organs and the percentage content of edible and inedible components in Koluda White geese.

    PubMed

    Murawska, Daria

    2013-05-01

    The parts of carcasses of slaughtered animals that are not intended for human consumption are referred to as inedible components. The total percentage of edible to inedible components in the carcasses of different poultry species is an important economic consideration. The objective of this study was to determine the effect of age on the growth rate of tissues and organs and the percentage change in edible to inedible components in geese. A flock of 240 Polish Koluda White geese was raised to 12 wk of age. The percentage content of edible components increased (P < 0.001) and the percentage content of inedible parts decreased (P < 0.001) as the birds grew older. Among edible components, the most considerable changes were noted in the growth rates of muscle tissue (10.5% increase; P < 0.001) and giblets (5.1% decrease; P < 0.001). The percentage share of muscle tissue increased to 10 wk of age. Lean meat weight increased from 175 g in wk 2 to 1,482 g in wk 12. The increase in lean meat weight varied considerably between body parts. The proportion of breast muscles in total meat weight increased substantially (by 26%), whereas the proportion of leg muscles decreased (by 34%). An increase in the weight of skin with subcutaneous fat was observed until the end of the rearing period, but the percentage content of this component remained at a similar level throughout the experiment (19.1 to 19.6%). The decrease in the percentage content of inedible components was mostly due to a decrease in the share of slaughter offal (by approximately 6.5%) because the proportion of bones remained at a stable level (approximately 11.9 to 11.5%). The weight of abdominal fat, which can be classified as edible or inedible, increased significantly with age, from 15.1 g in wk 2 to 205.1 g in wk 12, accounting for 1.6% and 4.0% total BW, respectively.

  1. Testicular failure

    MedlinePlus

    ... LH . Your doctor may also order a semen analysis to examine the number of healthy sperm you are producing. Sometimes, an ultrasound of the testes will be ordered. Testicular failure and low testosterone level may be hard to ...

  2. Interpretation of risk significance of passive component aging using probabilistic structural analysis

    SciTech Connect

    Phillips, J.H. ); Atwood, C.L. )

    1993-01-01

    The probabilistic risk assessments (PRAs) being developed at most nuclear power plants to calculate the risk of core damage generally focus on the possible failure of active components. Except as initiating events, the possible failure of passive components is given little consideration. The NRC is sponsoring a project at INEL to investigate the risk significance of passive components as they age. For this project, we developed a technique to calculate the failure probability of passive components over time, and demonstrated the technique by applying it to a weld in the auxiliary feedwater (AFW) system. A decreasing yearly rupture rate for this weld was calculated instead of the increasing rupture rate trend one might expect. We attribute this result to infant mortality; that is, most of those initial flaws that will eventually lead to rupture will do so early in life. This means that although each weld in a population may be wearing out, the population as a whole can exhibit a decreasing rupture rate. This observation has implications for passive components in commercial nuclear plants and other facilities where aging is a concern. For the population of passive components that exhibit a decreasing failure rate, risk increase is not a concern. The next step of the work is to identify the attributes that contribute to this decreasing rate, and to determine any attributes that would contribute to an increasing failure rate and thus to an increased risk.

  3. Interpretation of risk significance of passive component aging using probabilistic structural analysis

    SciTech Connect

    Phillips, J.H.; Atwood, C.L.

    1993-05-01

    The probabilistic risk assessments (PRAs) being developed at most nuclear power plants to calculate the risk of core damage generally focus on the possible failure of active components. Except as initiating events, the possible failure of passive components is given little consideration. The NRC is sponsoring a project at INEL to investigate the risk significance of passive components as they age. For this project, we developed a technique to calculate the failure probability of passive components over time, and demonstrated the technique by applying it to a weld in the auxiliary feedwater (AFW) system. A decreasing yearly rupture rate for this weld was calculated instead of the increasing rupture rate trend one might expect. We attribute this result to infant mortality; that is, most of those initial flaws that will eventually lead to rupture will do so early in life. This means that although each weld in a population may be wearing out, the population as a whole can exhibit a decreasing rupture rate. This observation has implications for passive components in commercial nuclear plants and other facilities where aging is a concern. For the population of passive components that exhibit a decreasing failure rate, risk increase is not a concern. The next step of the work is to identify the attributes that contribute to this decreasing rate, and to determine any attributes that would contribute to an increasing failure rate and thus to an increased risk.

  4. Predicting Computer System Failures Using Support Vector Machines

    SciTech Connect

    Fulp, Errin W.; Fink, Glenn A.; Haack, Jereme N.

    2008-12-07

    Mitigating the impact of computer failure is possible if accurate failure predictions are provided. Resources, applications, and services can be scheduled around predicted failure and limit the impact. Such strategies are especially important for multi-computer systems, such as compute clusters, that experience a higher rate failure due to the large number of components. However providing accurate predictions with sufficient lead time remains a challenging problem. This paper describes a new spectrum-kernel Support Vector Machine (SVM) approach to predict failure events based on system log files. These files contain messages that represent a change of system state. While a single message in the file may not be sufficient for predicting failure, a sequence or pattern of messages may be. The approach described in this paper will use a sliding window (sub-sequence) of messages to predict the likelihood of failure. The frequency representation of the message sub-sequences observed are then used as input to the SVM that associates the messages to a class of failed or non-failed system. Experimental results using actual system log files from a Linux-based compute cluster indicate the proposed SVM approach can predict hard disk failure with an accuracy of 76% one day in advance.

  5. High prevalence of dhfr triple mutant and correlation with high rates of sulphadoxine-pyrimethamine treatment failures in vivo in Gabonese children

    PubMed Central

    2011-01-01

    Background Drug resistance contributes to the global malaria burden. Plasmodium falciparum dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) polymorphisms confer resistance to sulphadoxine-pyrimethamine (SP). Methods The study assessed the frequency of SP resistance-conferring polymorphisms in Plasmodium falciparum-positive samples from two clinical studies in Lambaréné. Their role on treatment responses and transmission potential was studied in an efficacy open-label clinical trial with a 28-day follow-up in 29 children under five with uncomplicated malaria. Results SP was well tolerated by all subjects in vivo. Three subjects were excluded from per-protocol analysis. PCR-corrected, 12/26 (46%) achieved an adequate clinical and parasitological response, 13/26 (50%) were late parasitological failures, while 1/26 (4%) had an early treatment failure, resulting in early trial discontinuation. Of 106 isolates, 98 (92%) carried the triple mutant dhfr haplotype. Three point mutations were found in dhps in a variety of haplotypic configurations. The 437G + 540E double mutant allele was found for the first time in Gabon. Conclusions There is a high prevalence of dhfr triple mutant with some dhps point mutations in Gabon, in line with treatment failures observed, and molecular markers of SP resistance should be closely monitored. Trial Registration ClinicalTrials.gov: NCT00453856 PMID:21569596

  6. Analysis of nuclear power plant component failures

    SciTech Connect

    Not Available

    1984-01-01

    Items are shown that have caused 90% of the nuclear unit outages and/or deratings between 1971 and 1980 and the magnitude of the problem indicated by an estimate of power replacement cost when the units are out of service or derated. The funding EPRI has provided on these specific items for R and D and technology transfer in the past and the funding planned in the future (1982 to 1986) are shown. EPRI's R and D may help the utilities on only a small part of their nuclear unit outage problems. For example, refueling is the major cause for nuclear unit outages or deratings and the steam turbine is the second major cause for nuclear unit outages; however, these two items have been ranked fairly low on the EPRI priority list for R and D funding. Other items such as nuclear safety (NRC requirements), reactor general, reactor and safety valves and piping, and reactor fuel appear to be receiving more priority than is necessary as determined by analysis of nuclear unit outage causes.

  7. An evaluation of the relations between flow regime components, stream characteristics, species traits and meta-demographic rates of warmwater stream fishes: Implications for aquatic resource management

    USGS Publications Warehouse

    Peterson, James T.; Shea, C.P.

    2015-01-01

    Fishery biologists are increasingly recognizing the importance of considering the dynamic nature of streams when developing streamflow policies. Such approaches require information on how flow regimes influence the physical environment and how those factors, in turn, affect species-specific demographic rates. A more cost-effective alternative could be the use of dynamic occupancy models to predict how species are likely to respond to changes in flow. To appraise the efficacy of this approach, we evaluated relative support for hypothesized effects of seasonal streamflow components, stream channel characteristics, and fish species traits on local extinction, colonization, and recruitment (meta-demographic rates) of stream fishes. We used 4 years of seasonal fish collection data from 23 streams to fit multistate, multiseason occupancy models for 42 fish species in the lower Flint River Basin, Georgia. Modelling results suggested that meta-demographic rates were influenced by streamflows, particularly short-term (10-day) flows. Flow effects on meta-demographic rates also varied with stream size, channel morphology, and fish species traits. Small-bodied species with generalized life-history characteristics were more resilient to flow variability than large-bodied species with specialized life-history characteristics. Using this approach, we simplified the modelling framework, thereby facilitating the development of dynamic, spatially explicit evaluations of the ecological consequences of water resource development activities over broad geographic areas. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  8. Consent Procedures and Participation Rates in School-Based Intervention and Prevention Research: Using a Multi-Component, Partnership-Based Approach to Recruit Participants

    PubMed Central

    Leff, Stephen S.; Franko, Debra L.; Weinstein, Elana; Beakley, Kelly; Power, Thomas J.

    2009-01-01

    Evaluations of school-based interventions and prevention programs typically require parental consent for students to participate. In school-based efforts, program evaluators may have limited access to parents and considerable effort is required to obtain signed consent. This issue is particularly salient when conducting research in under-resourced, urban schools, where parent involvement in the school setting may be somewhat limited. The aims of this article were to (a) examine the published school-based prevention and intervention literature to assess the state of the field in terms of consent procedures and participation rates; and (b) describe two examples of health promotion studies that used multi-component, partnership-based strategies in urban schools to encourage communication among children, their parents, and researchers. The purpose of the case studies was to generate hypotheses to advance the science related to school-based participant recruitment for research studies. Of nearly 500 studies reviewed, only 11.5% reported both consent procedures and participation rates. Studies using active consent procedures had a mean participation rate of 65.5% (range: 11–100%). This article highlights the need for researchers to report consent procedures and participation rates and describes partnership-based strategies used to enroll students into two urban, school-based health promotion studies. PMID:19834586

  9. Weld failure detection

    DOEpatents

    Pennell, William E.; Sutton, Jr., Harry G.

    1981-01-01

    Method and apparatus for detecting failure in a welded connection, particrly applicable to not readily accessible welds such as those joining components within the reactor vessel of a nuclear reactor system. A preselected tag gas is sealed within a chamber which extends through selected portions of the base metal and weld deposit. In the event of a failure, such as development of a crack extending from the chamber to an outer surface, the tag gas is released. The environment about the welded area is directed to an analyzer which, in the event of presence of the tag gas, evidences the failure. A trigger gas can be included with the tag gas to actuate the analyzer.

  10. Heart failure.

    PubMed

    2014-12-15

    Essential facts Heart failure affects about 900,000 people in the UK. The condition can affect people of all ages, but it is more common in older people, with more than half of all patients over the age of 75. It is caused by the heart failing to pump enough blood around the body at the right pressure, usually because the heart muscle has become too weak or stiff to work properly. Acute heart failure, which occurs when symptoms develop quickly, is the leading cause of hospital admission in people over 65. PMID:25492766

  11. Structural failures: Causes, prevention, and misinterpretation

    SciTech Connect

    Barsom, J.M. )

    1993-07-01

    This article presents a few observations on causes and prevention of failures in structural and equipment components that are related to the initiation and propagation of fatigue cracks. Some of these observations are illustrated by using actual failures. Also, the article presents a discussion of some common misconceptions and misinterpretations that have led to incorrect conclusions in failure investigations.

  12. Heart Failure

    MedlinePlus

    ... of breath Common causes of heart failure are coronary artery disease, high blood pressure and diabetes. It is more common in people who are 65 years old or older, African Americans, people who are ... treatments fail. NIH: National Heart, Lung, and Blood Institute

  13. Failure of aseptic revision total knee arthroplasties

    PubMed Central

    Leta, Tesfaye H; Lygre, Stein Håkon L; Skredderstuen, Arne; Hallan, Geir; Furnes, Ove

    2015-01-01

    Background and purpose In Norway, the proportion of revision knee arthroplasties increased from 6.9% in 1994 to 8.5% in 2011. However, there is limited information on the epidemiology and causes of subsequent failure of revision knee arthroplasty. We therefore studied survival rate and determined the modes of failure of aseptic revision total knee arthroplasties. Method This study was based on 1,016 aseptic revision total knee arthroplasties reported to the Norwegian Arthroplasty Register between 1994 and 2011. Revisions done for infections were not included. Kaplan-Meier and Cox regression analyses were used to assess the survival rate and the relative risk of re-revision with all causes of re-revision as endpoint. Results 145 knees failed after revision total knee arthroplasty. Deep infection was the most frequent cause of re-revision (28%), followed by instability (26%), loose tibial component (17%), and pain (10%). The cumulative survival rate for revision total knee arthroplasties was 85% at 5 years, 78% at 10 years, and 71% at 15 years. Revision total knee arthroplasties with exchange of the femoral or tibial component exclusively had a higher risk of re-revision (RR = 1.7) than those with exchange of the whole prosthesis. The risk of re-revision was higher for men (RR = 2.0) and for patients aged less than 60 years (RR = 1.6). Interpretation In terms of implant survival, revision of the whole implant was better than revision of 1 component only. Young age and male sex were risk factors for re-revision. Deep infection was the most frequent cause of failure of revision of aseptic total knee arthroplasties. PMID:25267502

  14. Reliability estimation for check valves and other components

    SciTech Connect

    McElhaney, K.L.; Staunton, R.H.

    1996-06-01

    For years the nuclear industry has depended upon component operational reliability information compiled from reliability handbooks and other generic sources as well as private databases generated by recognized experts both within and outside the nuclear industry. Regrettably, these technical bases lacked the benefit of large-scale operational data and comprehensive data verification, and did not take into account the parameters and combinations of parameters that affect the determination of failure rates. This paper briefly examines the historic use of generic component reliability data, its sources, and its limitations. The concept of using a single failure rate for a particular component type is also examined. Particular emphasis is placed on check valves due to the information available on those components. The Appendix presents some of the results of the extensive analyses done by Oak Ridge National Laboratory (ORNL) on check valve performance.

  15. Reliability Quantification of Advanced Stirling Convertor (ASC) Components

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Korovaichuk, Igor; Zampino, Edward

    2010-01-01

    The Advanced Stirling Convertor, is intended to provide power for an unmanned planetary spacecraft and has an operational life requirement of 17 years. Over this 17 year mission, the ASC must provide power with desired performance and efficiency and require no corrective maintenance. Reliability demonstration testing for the ASC was found to be very limited due to schedule and resource constraints. Reliability demonstration must involve the application of analysis, system and component level testing, and simulation models, taken collectively. Therefore, computer simulation with limited test data verification is a viable approach to assess the reliability of ASC components. This approach is based on physics-of-failure mechanisms and involves the relationship among the design variables based on physics, mechanics, material behavior models, interaction of different components and their respective disciplines such as structures, materials, fluid, thermal, mechanical, electrical, etc. In addition, these models are based on the available test data, which can be updated, and analysis refined as more data and information becomes available. The failure mechanisms and causes of failure are included in the analysis, especially in light of the new information, in order to develop guidelines to improve design reliability and better operating controls to reduce the probability of failure. Quantified reliability assessment based on fundamental physical behavior of components and their relationship with other components has demonstrated itself to be a superior technique to conventional reliability approaches based on utilizing failure rates derived from similar equipment or simply expert judgment.

  16. Serologic responses to measles, mumps, and rubella (MMR) vaccine in healthy infants: failure to respond to measles and mumps components may influence decisions on timing of the second dose of MMR.

    PubMed

    Mitchell, L A; Tingle, A J; Décarie, D; Lajeunesse, C

    1998-01-01

    Measles, mumps, and rubella-specific IgG antibodies were evaluated in 134 healthy infants routinely immunized with trivalent live attenuated measles-mumps-rubella (MMR) vaccine at one year of age. Blood samples were collected just before, and at 1, 3, and 12 months after MMR. Specific IgG was measured by commercial enzyme immunoassays. Before vaccination, 98.5%, 99.2%, and 98.5% of the infants tested were seronegative for measles, mumps, and rubella, respectively. One year after MMR, 16.4% and 22.4% of vaccinees lacked demonstrable antibody to measles and mumps while none were found to be seronegative for rubella. Response profile analysis revealed primary failure rates of 12.1% (measles) and 8.6% (mumps) while 4% (measles) and 13.8% (mumps) of the infants responded initially but became seronegative within one year. These observations suggest that earlier administration (at age 18 months) of the second dose of MMR may be more desirable than revaccination at school entry.

  17. Metabolic growth rate control in Escherichia coli may be a consequence of subsaturation of the macromolecular biosynthetic apparatus with substrates and catalytic components.

    PubMed

    Jensen, K F; Pedersen, S

    1990-06-01

    In this paper, the Escherichia coli cell is considered as a system designed for rapid growth, but limited by the medium. We propose that this very design causes the cell to become subsaturated with precursors and catalytic components at all levels of macromolecular biosynthesis and leads to a molecular sharing economy at a high level of competition inside the cell. Thus, the promoters compete with each other in the binding of a limited amount of free RNA polymerase and the ribosome binding sites on the mRNA chains compete with each other for the free ribosomes. The macromolecular chain elongation reactions sequester a considerable proportion of the total amount of RNA polymerase and ribosomes in the cells. We propose that the degree of subsaturation of the macromolecular biosynthetic apparatus renders a variable fraction of RNA polymerase and ribosomes unavailable for the initiation of new chain synthesis and that this, at least in part, determines the composition of the cell as a function of the growth rate. Thus, at rapid growth, the high speed of the elongation reactions enables the cell to increase the concentrations of free RNA polymerase and ribosomes for initiation purposes. Furthermore, it is proposed that the speed of RNA polymerase movement is adjusted to the performance speed of the ribosomes. Mechanistically, this adjustment of the coupling between transcription and translation involves transcriptional pause sites along the RNA chains, the adjustment of the saturation level of RNA polymerase with the nucleoside triphosphate substrates, and the concentration of ppGpp, which is known to inhibit RNA chain elongation. This model is able to explain the stringent response and the control of stable RNA and of ribosome synthesis in steady states and in shifts, as well as the rate of overall protein synthesis as a function of the growth rate. PMID:1694554

  18. Metabolic growth rate control in Escherichia coli may be a consequence of subsaturation of the macromolecular biosynthetic apparatus with substrates and catalytic components.

    PubMed Central

    Jensen, K F; Pedersen, S

    1990-01-01

    In this paper, the Escherichia coli cell is considered as a system designed for rapid growth, but limited by the medium. We propose that this very design causes the cell to become subsaturated with precursors and catalytic components at all levels of macromolecular biosynthesis and leads to a molecular sharing economy at a high level of competition inside the cell. Thus, the promoters compete with each other in the binding of a limited amount of free RNA polymerase and the ribosome binding sites on the mRNA chains compete with each other for the free ribosomes. The macromolecular chain elongation reactions sequester a considerable proportion of the total amount of RNA polymerase and ribosomes in the cells. We propose that the degree of subsaturation of the macromolecular biosynthetic apparatus renders a variable fraction of RNA polymerase and ribosomes unavailable for the initiation of new chain synthesis and that this, at least in part, determines the composition of the cell as a function of the growth rate. Thus, at rapid growth, the high speed of the elongation reactions enables the cell to increase the concentrations of free RNA polymerase and ribosomes for initiation purposes. Furthermore, it is proposed that the speed of RNA polymerase movement is adjusted to the performance speed of the ribosomes. Mechanistically, this adjustment of the coupling between transcription and translation involves transcriptional pause sites along the RNA chains, the adjustment of the saturation level of RNA polymerase with the nucleoside triphosphate substrates, and the concentration of ppGpp, which is known to inhibit RNA chain elongation. This model is able to explain the stringent response and the control of stable RNA and of ribosome synthesis in steady states and in shifts, as well as the rate of overall protein synthesis as a function of the growth rate. PMID:1694554

  19. Metabolic growth rate control in Escherichia coli may be a consequence of subsaturation of the macromolecular biosynthetic apparatus with substrates and catalytic components.

    PubMed

    Jensen, K F; Pedersen, S

    1990-06-01

    In this paper, the Escherichia coli cell is considered as a system designed for rapid growth, but limited by the medium. We propose that this very design causes the cell to become subsaturated with precursors and catalytic components at all levels of macromolecular biosynthesis and leads to a molecular sharing economy at a high level of competition inside the cell. Thus, the promoters compete with each other in the binding of a limited amount of free RNA polymerase and the ribosome binding sites on the mRNA chains compete with each other for the free ribosomes. The macromolecular chain elongation reactions sequester a considerable proportion of the total amount of RNA polymerase and ribosomes in the cells. We propose that the degree of subsaturation of the macromolecular biosynthetic apparatus renders a variable fraction of RNA polymerase and ribosomes unavailable for the initiation of new chain synthesis and that this, at least in part, determines the composition of the cell as a function of the growth rate. Thus, at rapid growth, the high speed of the elongation reactions enables the cell to increase the concentrations of free RNA polymerase and ribosomes for initiation purposes. Furthermore, it is proposed that the speed of RNA polymerase movement is adjusted to the performance speed of the ribosomes. Mechanistically, this adjustment of the coupling between transcription and translation involves transcriptional pause sites along the RNA chains, the adjustment of the saturation level of RNA polymerase with the nucleoside triphosphate substrates, and the concentration of ppGpp, which is known to inhibit RNA chain elongation. This model is able to explain the stringent response and the control of stable RNA and of ribosome synthesis in steady states and in shifts, as well as the rate of overall protein synthesis as a function of the growth rate.

  20. Determinants of Toxicity, Patterns of Failure, and Outcome Among Adult Patients With Soft Tissue Sarcomas of the Extremity and Superficial Trunk Treated With Greater Than Conventional Doses of Perioperative High-Dose-Rate Brachytherapy and External Beam Radiotherapy

    SciTech Connect

    San Miguel, Inigo; San Julian, Mikel; Cambeiro, Mauricio; Sanmamed, Miguel Fernandez; Vazquez-Garcia, Blanca; Pagola, Maria; Gaztanaga, Miren; Martin-Algarra, Salvador; Martinez-Monge, Rafael

    2011-11-15

    Purpose: The present study was undertaken to determine factors predictive of toxicity, patterns of failure, and survival in 60 adult patients with soft tissue sarcomas of the extremity and superficial trunk treated with combined perioperative high-dose-rate brachytherapy and external beam radiotherapy. Methods and Materials: The patients were treated with surgical resection and perioperative high-dose-rate brachytherapy (16 or 24 Gy) for negative and close/microscopically positive resection margins, respectively. External beam radiotherapy (45 Gy) was added postoperatively to reach a 2-Gy equivalent dose of 62.9 and 72.3 Gy, respectively. Adjuvant chemotherapy with ifosfamide and doxorubicin was given to patients with advanced high-grade tumors. Results: Grade 3 toxic events were observed in 18 patients (30%) and Grade 4 events in 6 patients (10%). No Grade 5 events were observed. A location in the lower limb was significant for Grade 3 or greater toxic events on multivariate analysis (p = .013), and the tissue volume encompassed by the 150% isodose line showed a trend toward statistical significance (p = .086). The local control, locoregional control, and distant control rate at 9 years was 77.4%, 69.5%, and 63.8%, respectively. On multivariate analysis, microscopically involved margins correlated with local control (p = .036) and locoregional control (p = .007) and tumor size correlated with distant metastases (p = .004). The 9-year disease-free survival and overall survival rate was 47.0% and 61.5%, respectively. Multivariate analysis showed poorer disease-free survival rates for patients with tumors >6 cm (p = .005) and microscopically involved margins (p = .043), and overall survival rates decreased with increasing tumor size (p = .011). Conclusions: Grade 3 or greater wound complications can probably be decreased using meticulous treatment planning to decrease the tissue volume encompassed by the 150% isodose line, especially in lower limb locations

  1. How Is Respiratory Failure Treated?

    MedlinePlus

    ... Once your doctor figures out what's causing your respiratory failure, he or she will plan how to treat that disease or condition. Treatments may include medicines, procedures, and other therapies. Rate This Content: NEXT >> Updated: December 19, 2011 Twitter ...

  2. Enhanced Component Performance Study. Emergency Diesel Generators 1998–2013

    SciTech Connect

    Schroeder, John Alton

    2014-11-01

    This report presents an enhanced performance evaluation of emergency diesel generators (EDGs) at U.S. commercial nuclear power plants. This report evaluates component performance over time using Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES) data from 1998 through 2013 and maintenance unavailability (UA) performance data using Mitigating Systems Performance Index (MSPI) Basis Document data from 2002 through 2013. The objective is to present an analysis of factors that could influence the system and component trends in addition to annual performance trends of failure rates and probabilities. The factors analyzed for the EDG component are the differences in failures between all demands and actual unplanned engineered safety feature (ESF) demands, differences among manufacturers, and differences among EDG ratings. Statistical analyses of these differences are performed and results showing whether pooling is acceptable across these factors. In addition, engineering analyses were performed with respect to time period and failure mode. The factors analyzed are: sub-component, failure cause, detection method, recovery, manufacturer, and EDG rating.

  3. Definition of ACLF and inclusion criteria for extra-hepatic organ failure.

    PubMed

    Wang, Xiaojing; Sarin, Shiv Kumar; Ning, Qin

    2015-07-01

    A prominent characteristic of ACLF is rapid hepatic disease progression with subsequent extra-hepatic organ failure, manifesting as either hepatic coma or hepatorenal syndrome, which is associated with a high mortality rate in a short time. The APASL definition mainly emphasizes recognizing patients with hepatic failure. These patients may subsequently develop extra-hepatic multisystem organ failure leading to high mortality. It is therefore worthwhile to identify the short interim period between the development of liver failure and the onset of extra-hepatic organ failure, the potential therapeutic 'golden window.' Interventions during this period may prevent the development of complications and eventually change the course of the illness. Organ failure is suggested to be a central component of ACLF and may behave differently from chronic decompensated liver disease. Clear and practical criteria for the inclusion of organ failure are urgently needed so that patients with these life-threatening complications can be treated in a timely and appropriate manner. Recent studies suggested that the scoring systems evaluating organ failure [acute physiology, age and chronic health evaluation (APACHE) and sequential organ failure assessment (SOFA) scores] work better than those addressing the severity of liver disease [Child-Pugh and model of end-stage liver disease (MELD) scores] in ACLF. However, a key problem remains that the former scoring systems are reflective of organ failure and not predictive, thus limiting their value as an early indication for intervention.

  4. Real-world examples of sensitivity failures of the 3%/3mm pass rate metric and published action levels when used in IMRT/VMAT system commissioning

    NASA Astrophysics Data System (ADS)

    Nelms, B.; Jarry, G.; Chan, M.; Hampton, C.; Watanabe, Y.; Feygelman, V.

    2013-06-01

    In IMRT/VMAT system commissioning (as with any system), quality is improved by striving for tight tolerances of stringent metrics of accuracy. For 5 cases, passing rates for 3%/3mm gamma analysis were generated following the TG119 instructions. Subsequently, more stringent/sensitive criteria combined with advanced volumetric dose analysis were applied, and in each case significant systematic errors were clearly identified despite the high 3%/3mm passing rates. In 4 of 5 cases, the error was easily remedied. These real-world examples of observed "false negatives" (insensitivities) point towards the inappropriateness of the 3%/3mm gamma passing rate metric as the basis for acceptance testing/commissioning of the IMRT/VMAT delivery chain.

  5. Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design [Morphological design of silicon electrode with anisotropic interface reaction rate for lithium ion batteries

    DOE PAGESBeta

    An, Yonghao; Wood, Brandon C.; Ye, Jianchao; Chiang, Yet -Ming; Wang, Y. Morris; Tang, Ming; Jiang, Hanqing

    2015-06-08

    Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteractmore » the anisotropy in the crystalline/amorphous interface velocity. This produces a much more uniform volume expansion, significantly reducing strain concentration. Based on a new, validated methodology that improves previous models of anisotropic swelling of c-Si, we propose optimal morphological designs for c-Si pillars and particles. The advantages of the new morphologies are clearly demonstrated by mesoscale simulations and verified by experiments on engineered c-Si micropillars. The results of this study illustrate that morphological design is effective in improving the fracture resistance of micron-sized Si electrodes, which will facilitate their practical application in next-generation Li-ion batteries. In conclusion, the model and design approach present in this paper also have general implications for the study and mitigation of mechanical failure of electrode materials that undergo large anisotropic volume change upon ion insertion and extraction.« less

  6. Effect of Early Intervention With Positive Airway Pressure Therapy for Sleep Disordered Breathing on Six-Month Readmission Rates in Hospitalized Patients With Heart Failure.

    PubMed

    Sharma, Sunil; Mather, Paul; Gupta, Ankit; Reeves, Gordon; Rubin, Sharon; Bonita, Raphael; Chowdhury, Anindita; Malloy, Raymond; Willes, Leslee; Whellan, David

    2016-03-15

    Rehospitalization for congestive heart failure (CHF) is high within 6 months of discharge. Sleep disordered breathing (SDB) is common and underdiagnosed condition in patients with CHF. We hypothesized that early recognition and treatment of SDB in hospitalized patients with CHF will reduce hospital readmissions and emergency room visits. Patients admitted for CHF underwent overnight polysomnography within 4 weeks of discharge. Patients diagnosed with SDB were provided therapy with positive airway pressure therapy. Patients were identified as having good compliance if the device use was for a minimum of 4 hours 70% of the time for a minimum of 4 weeks during the first 3 months of therapy. Hospital admissions for 6 months before therapy were compared with readmission within 6 months after therapy in patients with good and poor compliance. A total of 70 patients were diagnosed with SDB after discharge. Of the 70 patients, 37 (53%) were compliant with positive airway pressure therapy. Compliant patients were more likely to be older (64 ± 12 vs 58 ± 11 years) and women (54% vs 33%) and less likely to be patient with diabetes (40% vs 67%) versus noncompliant patients. Although both groups experienced a decrease in total readmissions, compliant patients had a significant reduction (mean ± SE: -1.5 ± 0.2 clinical events vs -0.2 ± 0.3; p <0.0001). In this single-center analysis, identification and treatment of SDB in admitted patients with CHF with SDB is associated with reduced readmissions over 6 months after discharge. Adherence to the treatment was associated with a greater reduction in clinical events. PMID:26830259

  7. Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design [Morphological design of silicon electrode with anisotropic interface reaction rate for lithium ion batteries

    SciTech Connect

    An, Yonghao; Wood, Brandon C.; Ye, Jianchao; Chiang, Yet -Ming; Wang, Y. Morris; Tang, Ming; Jiang, Hanqing

    2015-06-08

    Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity. This produces a much more uniform volume expansion, significantly reducing strain concentration. Based on a new, validated methodology that improves previous models of anisotropic swelling of c-Si, we propose optimal morphological designs for c-Si pillars and particles. The advantages of the new morphologies are clearly demonstrated by mesoscale simulations and verified by experiments on engineered c-Si micropillars. The results of this study illustrate that morphological design is effective in improving the fracture resistance of micron-sized Si electrodes, which will facilitate their practical application in next-generation Li-ion batteries. In conclusion, the model and design approach present in this paper also have general implications for the study and mitigation of mechanical failure of electrode materials that undergo large anisotropic volume change upon ion insertion and extraction.

  8. Is Student Success Labeled Institutional Failure? Student Goals and Graduation Rates in the Accountability Debate at Community Colleges. CCRC Working Paper No. 1

    ERIC Educational Resources Information Center

    Bailey, Thomas; Jenkins, Davis; Leinbach, Timothy

    2005-01-01

    Community colleges are open-door institutions serving many students with academic, economic, and personal characteristics that can make college completion a challenge. Their graduation rates are low, but community college students do not always have earning a degree as their goal. While individual students may feel that their experience at a…

  9. Cascaded failures in weighted networks.

    PubMed

    Mirzasoleiman, Baharan; Babaei, Mahmoudreza; Jalili, Mahdi; Safari, Mohammadali

    2011-10-01

    Many technological networks can experience random and/or systematic failures in their components. More destructive situations can happen if the components have limited capacity, where the failure in one of them might lead to a cascade of failures in other components, and consequently break down the structure of the network. In this paper, the tolerance of cascaded failures was investigated in weighted networks. Three weighting strategies were considered including the betweenness centrality of the edges, the product of the degrees of the end nodes, and the product of their betweenness centralities. Then, the effect of the cascaded attack was investigated by considering the local weighted flow redistribution rule. The capacity of the edges was considered to be proportional to their initial weight distribution. The size of the survived part of the attacked network was determined in model networks as well as in a number of real-world networks including the power grid, the internet in the level of autonomous system, the railway network of Europe, and the United States airports network. We found that the networks in which the weight of each edge is the multiplication of the betweenness centrality of the end nodes had the best robustness against cascaded failures. In other words, the case where the load of the links is considered to be the product of the betweenness centrality of the end nodes is favored for the robustness of the network against cascaded failures.

  10. New understandings of failure modes in SSL luminaires

    NASA Astrophysics Data System (ADS)

    Shepherd, Sarah D.; Mills, Karmann C.; Yaga, Robert; Johnson, Cortina; Davis, J. Lynn

    2014-09-01

    As SSL products are being rapidly introduced into the market, there is a need to develop standard screening and testing protocols that can be performed quickly and provide data surrounding product lifetime and performance. These protocols, derived from standard industry tests, are known as ALTs (accelerated life tests) and can be performed in a timeframe of weeks to months instead of years. Accelerated testing utilizes a combination of elevated temperature and humidity conditions as well as electrical power cycling to control aging of the luminaires. In this study, we report on the findings of failure modes for two different luminaire products exposed to temperature-humidity ALTs. LEDs are typically considered the determining component for the rate of lumen depreciation. However, this study has shown that each luminaire component can independently or jointly influence system performance and reliability. Material choices, luminaire designs, and driver designs all have significant impacts on the system reliability of a product. From recent data, it is evident that the most common failure modes are not within the LED, but instead occur within resistors, capacitors, and other electrical components of the driver. Insights into failure modes and rates as a result of ALTs are reported with emphasis on component influence on overall system reliability.

  11. New understandings of failure modes in SSL luminaires

    SciTech Connect

    Shepherd, Sarah D; Mills, Karmann C; Yaga, Robert; Johnson, Cortina; Davis, J Lynn

    2014-09-18

    As SSL products are being rapidly introduced into the market, there is a need to develop standard screening and testing protocols that can be performed quickly and provide data surrounding product lifetime and performance. These protocols, derived from standard industry tests, are known as ALTs (accelerated life tests) and can be performed in a timeframe of weeks to months instead of years. Accelerated testing utilizes a combination of elevated temperature and humidity conditions as well as electrical power cycling to control aging of the luminaires. In this study, we report on the findings of failure modes for two different luminaire products exposed to temperature-humidity ALTs. LEDs are typically considered the determining component for the rate of lumen depreciation. However, this study has shown that each luminaire component can independently or jointly influence system performance and reliability. Material choices, luminaire designs, and driver designs all have significant impacts on the system reliability of a product. From recent data, it is evident that the most common failure modes are not within the LED, but instead occur within resistors, capacitors, and other electrical components of the driver. Insights into failure modes and rates as a result of ALTs are reported with emphasis on component influence on overall system reliability.

  12. Failure mode analysis using state variables derived from fault trees with application

    SciTech Connect

    Bartholomew, R.J.

    1981-01-01

    Fault Tree Analysis (FTA) is used extensively to assess both the qualitative and quantitative reliability of engineered nuclear power systems employing many subsystems and components. FTA is very useful, but the method is limited by its inability to account for failure mode rate-of-change interdependencies (coupling) of statistically independent failure modes. The state variable approach (using FTA-derived failure modes as states) overcomes these difficulties and is applied to the determination of the lifetime distribution function for a heat pipe-thermoelectric nuclear power subsystem. Analyses are made using both Monte Carlo and deterministic methods and compared with a Markov model of the same subsystem.

  13. A comprehensive analysis of the physiological and anatomical components involved in higher water loss rates after leaf development at high humidity.

    PubMed

    Fanourakis, Dimitrios; Heuvelink, Ep; Carvalho, Susana M P

    2013-07-01

    To better understand the poor regulation of water loss after leaf development at high relative air humidity (RH), the relative importance of the physiological and anatomical components was analyzed focusing on cultivars with a contrasting sensitivity to elevated RH. The stomatal responsiveness to three closing stimuli (desiccation, abscisic acid feeding, light/dark transition), as well as several stomatal features (density, index, size and pore dimensions) and the cuticular transpiration rate (CTR) were determined in four rose cultivars, grown under moderate (60%) and high (95%) RH. Moreover, the effects of changes in stomatal density and pore dimensions on the stomatal conductance (gs) were quantified using a modified version of the Brown and Escombe equation. Higher water loss, as a result of plant growth at high RH, was primarily caused by an increase in residual gs, and to a lesser extent due to higher CTR. It was estimated that in leaflets subjected to desiccation the enhanced gs in high RH- as compared to moderate RH-grown plants was mostly due to poor stomatal functionality and to a lesser extent the combined result of higher stomatal density and longer pore length. It is concluded that the reduced degree and, specially, the reduced rate of stomatal closure are the primary causes of the large genotypic variation in the control of water loss in high RH-grown plants. Furthermore, it was found that although changes in stomatal length have no influence on stomatal functionality, changed anatomical features per se represent a significant and direct contribution to the increased water loss. PMID:23474196

  14. Crack growth rates and metallographic examinations of Alloy 600 and Alloy 82/182 from field components and laboratory materials tested in PWR environments.

    SciTech Connect

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.

    2008-05-05

    In light water reactors, components made of nickel-base alloys are susceptible to environmentally assisted cracking. This report summarizes the crack growth rate results and related metallography for field and laboratory-procured Alloy 600 and its weld alloys tested in pressurized water reactor (PWR) environments. The report also presents crack growth rate (CGR) results for a shielded-metal-arc weld of Alloy 182 in a simulated PWR environment as a function of temperature between 290 C and 350 C. These data were used to determine the activation energy for crack growth in Alloy 182 welds. The tests were performed by measuring the changes in the stress corrosion CGR as the temperatures were varied during the test. The difference in electrochemical potential between the specimen and the Ni/NiO line was maintained constant at each temperature by adjusting the hydrogen overpressure on the water supply tank. The CGR data as a function of temperature yielded activation energies of 252 kJ/mol for a double-J weld and 189 kJ/mol for a deep-groove weld. These values are in good agreement with the data reported in the literature. The data reported here and those in the literature suggest that the average activation energy for Alloy 182 welds is on the order of 220-230 kJ/mol, higher than the 130 kJ/mol commonly used for Alloy 600. The consequences of using a larger value of activation energy for SCC CGR data analysis are discussed.

  15. The effect of time step, thermostat, and strain rate on ReaxFF simulations of mechanical failure in diamond, graphene, and carbon nanotube.

    PubMed

    Jensen, Benjamin D; Wise, Kristopher E; Odegard, Gregory M

    2015-08-01

    As the sophistication of reactive force fields for molecular modeling continues to increase, their use and applicability has also expanded, sometimes beyond the scope of their original development. Reax Force Field (ReaxFF), for example, was originally developed to model chemical reactions, but is a promising candidate for modeling fracture because of its ability to treat covalent bond cleavage. Performing reliable simulations of a complex process like fracture, however, requires an understanding of the effects that various modeling parameters have on the behavior of the system. This work assesses the effects of time step size, thermostat algorithm and coupling coefficient, and strain rate on the fracture behavior of three carbon-based materials: graphene, diamond, and a carbon nanotube. It is determined that the simulated stress-strain behavior is relatively independent of the thermostat algorithm, so long as coupling coefficients are kept above a certain threshold. Likewise, the stress-strain response of the materials was also independent of the strain rate, if it is kept below a maximum strain rate. Finally, the mechanical properties of the materials predicted by the Chenoweth C/H/O parameterization for ReaxFF are compared with literature values. Some deficiencies in the Chenoweth C/H/O parameterization for predicting mechanical properties of carbon materials are observed.

  16. High rates of virological failure and drug resistance in perinatally HIV-1-infected children and adolescents receiving lifelong antiretroviral therapy in routine clinics in Togo

    PubMed Central

    Salou, Mounerou; Dagnra, Anoumou Y; Butel, Christelle; Vidal, Nicole; Serrano, Laetitia; Takassi, Elom; Konou, Abla A; Houndenou, Spero; Dapam, Nina; Singo-Tokofaï, Assetina; Pitche, Palokinam; Atakouma, Yao; Prince-David, Mireille; Delaporte, Eric; Peeters, Martine

    2016-01-01

    Introduction Antiretroviral treatment (ART) has been scaled up over the last decade but compared to adults, children living with HIV are less likely to receive ART. Moreover, children and adolescents are more vulnerable than adults to virological failure (VF) and emergence of drug resistance. In this study we determined virological outcome in perinatally HIV-1-infected children and adolescents receiving ART in Togo. Methods HIV viral load (VL) testing was consecutively proposed to all children and adolescents who were on ART for at least 12 months when attending HIV healthcare services for their routine follow-up visit (June to September 2014). Plasma HIV-1 VL was measured using the m2000 RealTime HIV-1 assay (Abbott Molecular, Des Plaines, IL, USA). Genotypic drug resistance was done for all samples with VL>1000 copies/ml. Results and discussion Among 283 perinatally HIV-1-infected children and adolescents included, 167 (59%) were adolescents and 116 (41%) were children. The median duration on ART was 48 months (interquartile range: 28 to 68 months). For 228 (80.6%), the current ART combination consisted of two nucleoside reverse transcriptase inhibitors (NRTIs) (zidovudine and lamivudine) and one non-nucleoside reverse transcriptase inhibitor (NNRTI) (nevirapine or efavirenz). Only 28 (9.9%) were on a protease inhibitor (PI)-based regimen. VL was below the detection limit (i.e. 40 copies/ml) for 102 (36%), between 40 and 1000 copies/ml for 35 (12.4%) and above 1000 copies/ml for 146 (51.6%). Genotypic drug-resistance testing was successful for 125/146 (85.6%); 110/125 (88.0%) were resistant to both NRTIs and NNRTIs, 1/125 (0.8%) to NRTIs only, 4/125 (3.2%) to NNRTIs only and three harboured viruses resistant to reverse transcriptase and PIs. Overall, 86% (108/125) of children and adolescents experiencing VF and successfully genotyped, corresponding thus to at least 38% of the study population, had either no effective ART or had only a single effective drug in

  17. The Evaluation of a Rapid In Situ HIV Confirmation Test in a Programme with a High Failure Rate of the WHO HIV Two-Test Diagnostic Algorithm

    PubMed Central

    Klarkowski, Derryck B.; Wazome, Joseph M.; Lokuge, Kamalini M.; Shanks, Leslie; Mills, Clair F.; O'Brien, Daniel P.

    2009-01-01

    Background Concerns about false-positive HIV results led to a review of testing procedures used in a Médecins Sans Frontières (MSF) HIV programme in Bukavu, eastern Democratic Republic of Congo. In addition to the WHO HIV rapid diagnostic test algorithm (RDT) (two positive RDTs alone for HIV diagnosis) used in voluntary counselling and testing (VCT) sites we evaluated in situ a practical field-based confirmation test against western blot WB. In addition, we aimed to determine the false-positive rate of the WHO two-test algorithm compared with our adapted protocol including confirmation testing, and whether weakly reactive compared with strongly reactive rapid test results were more likely to be false positives. Methodology/Principal Findings 2864 clients presenting to MSF VCT centres in Bukavu during January to May 2006 were tested using Determine HIV-1/2® and UniGold HIV® rapid tests in parallel by nurse counsellors. Plasma samples on 229 clients confirmed as double RDT positive by laboratory retesting were further tested using both WB and the Orgenics Immunocomb Combfirm® HIV confirmation test (OIC-HIV). Of these, 24 samples were negative or indeterminate by WB representing a false-positive rate of the WHO two-test algorithm of 10.5% (95%CI 6.6-15.2). 17 of the 229 samples were weakly positive on rapid testing and all were negative or indeterminate by WB. The false-positive rate fell to 3.3% (95%CI 1.3–6.7) when only strong-positive rapid test results were considered. Agreement between OIC-HIV and WB was 99.1% (95%CI 96.9–99.9%) with no false OIC-HIV positives if stringent criteria for positive OIC-HIV diagnoses were used. Conclusions The WHO HIV two-test diagnostic algorithm produced an unacceptably high level of false-positive diagnoses in our setting, especially if results were weakly positive. The most probable causes of the false-positive results were serological cross-reactivity or non-specific immune reactivity. Our findings show that the OIC

  18. Do bisexual girls report higher rates of substance use than heterosexual girls? A failure to replicate with incarcerated and detained youth

    PubMed Central

    Bernstein, Michael H.; Stein, L.A.R.

    2016-01-01

    Prior research suggests that sexual minority females, particularly bisexuals, report greater rates of substance use than heterosexuals. However, to our knowledge, no study has compared alcohol/drug use between bisexual and heterosexual incarcerated or detained female youth. The current study pools data from three prior treatment studies with incarcerated or detained adolescent girls that self-identify as bisexual or heterosexual (N=86). Hierarchical regression models were conducted to determine whether 12-month prevalence of alcohol, cigarettes, marijuana, or other drug use differed between bisexual and heterosexual participants. In contrast to most prior work, no differences were observed. Findings are considered in light of the recruitment setting, which drew a sample with high levels of substance use prevalence. PMID:27087787

  19. Analyses of component degradation to evaluate maintenance effectiveness and aging effects

    SciTech Connect

    Samanta, P.K.; Hsu, F.; Subudhi, M. ); Vesely, W.E. )

    1991-01-01

    This paper describes degradation modeling, an approach for analyzing degradation and failure of components to understand the aging process of components. As used in our study, degradation modeling is the analysis of information on degradation of components for developing models of the degradation process and its implications. This modeling focuses on the analysis of the times of degradations of components, to model how the rate of degradation changes with the age of the component. With this methodology we also determine the effectiveness of maintenance as applicable to aging evaluations. The specific applications which are performed show quantitative models of degradation rates of components and failure rates of components from plant-specific data. The statistical techniques allow aging trends to be identified in the degradation data and in the failure data. Initial estimates of the effectiveness of maintenance in limiting degradations from becoming failures are developed. These results are important first steps in degradation modeling, and show that degradation can be modeled to identify aging trends. 2 refs., 8 figs., 1 tab.

  20. A general cause based methodology for analysis of dependent failures in system risk and reliability assessments

    NASA Astrophysics Data System (ADS)

    O'Connor, Andrew N.

    Bayesian Network to model the soft dependencies between components. This is done through the introduction of three parameters for each failure cause that relate to component fragility, failure cause rate, and failure cause propagation probability.

  1. Component Repair Times Obtained from MSPI Data

    SciTech Connect

    Eide, Steven A.

    2015-05-01

    Information concerning times to repair or restore equipment to service given a failure is valuable to probabilistic risk assessments (PRAs). Examples of such uses in modern PRAs include estimation of the probability of failing to restore a failed component within a specified time period (typically tied to recovering a mitigating system before core damage occurs at nuclear power plants) and the determination of mission times for support system initiating event (SSIE) fault tree models. Information on equipment repair or restoration times applicable to PRA modeling is limited and dated for U.S. commercial nuclear power plants. However, the Mitigating Systems Performance Index (MSPI) program covering all U.S. commercial nuclear power plants provides up-to-date information on restoration times for a limited set of component types. This paper describes the MSPI program data available and analyzes the data to obtain median and mean component restoration times as well as non-restoration cumulative probability curves. The MSPI program provides guidance for monitoring both planned and unplanned outages of trains of selected mitigating systems deemed important to safety. For systems included within the MSPI program, plants monitor both train UA and component unreliability (UR) against baseline values. If the combined system UA and UR increases sufficiently above established baseline results (converted to an estimated change in core damage frequency or CDF), a “white” (or worse) indicator is generated for that system. That in turn results in increased oversight by the US Nuclear Regulatory Commission (NRC) and can impact a plant’s insurance rating. Therefore, there is pressure to return MSPI program components to service as soon as possible after a failure occurs. Three sets of unplanned outages might be used to determine the component repair durations desired in this article: all unplanned outages for the train type that includes the component of interest, only

  2. Predicting Failure Progression and Failure Loads in Composite Open-Hole Tension Coupons

    NASA Technical Reports Server (NTRS)

    Arunkumar, Satyanarayana; Przekop, Adam

    2010-01-01

    Failure types and failure loads in carbon-epoxy [45n/90n/-45n/0n]ms laminate coupons with central circular holes subjected to tensile load are simulated using progressive failure analysis (PFA) methodology. The progressive failure methodology is implemented using VUMAT subroutine within the ABAQUS(TradeMark)/Explicit nonlinear finite element code. The degradation model adopted in the present PFA methodology uses an instantaneous complete stress reduction (COSTR) approach to simulate damage at a material point when failure occurs. In-plane modeling parameters such as element size and shape are held constant in the finite element models, irrespective of laminate thickness and hole size, to predict failure loads and failure progression. Comparison to published test data indicates that this methodology accurately simulates brittle, pull-out and delamination failure types. The sensitivity of the failure progression and the failure load to analytical loading rates and solvers precision is demonstrated.

  3. Failure mode analysis to predict product reliability.

    NASA Technical Reports Server (NTRS)

    Zemanick, P. P.

    1972-01-01

    The failure mode analysis (FMA) is described as a design tool to predict and improve product reliability. The objectives of the failure mode analysis are presented as they influence component design, configuration selection, the product test program, the quality assurance plan, and engineering analysis priorities. The detailed mechanics of performing a failure mode analysis are discussed, including one suggested format. Some practical difficulties of implementation are indicated, drawn from experience with preparing FMAs on the nuclear rocket engine program.

  4. Strain limit criteria to predict failure

    SciTech Connect

    Flanders, H.E.

    1995-12-31

    In recent years extensive effort has been expended to qualify existing structures for conditions that are beyond the original design basis. Determination of the component failure load is useful for this type of evaluation. This paper presents criteria based upon strain limits to predict the load at failure. The failure modes addressed are excessive plastic deformations, localized plastic strains, and structural instability. The effects of analytical method sophistication, as built configurations, material properties degradation, and stress state are addressed by the criteria.

  5. [Failure effects and gender differences in perfectionism].

    PubMed

    Masson, A M; Cadot, M; Ansseau, M

    2003-01-01

    perfectionism are described: SOP (Self Oriented Perfectionism) related to high standards and self criticism, SPP (Socially Prescribed Perfectionism) related to the need of approval from others and fear of negative evaluation, OOP (Other-Oriented Perfectionism) reflecting a tendency to set high expectations for others and to evaluate them in a demanding way; this component is related, especially for males, to self-esteem, hostility and authoritarianism. Validity and internal consistency have been established too (30, 31, 35). The Frost and al's Multidimensional Perfectionism Scale and the Hewitt and Flett's scales are closely associated, except concerning the OOP. Because this component could provide new information, we have chosen the second scale, referring to the French translation and validation of Labrecque (45). EMP is the French name of MPS; it is a self-report questionnaire of 45 questions, in fact three subscales of 15 items rated on a 7-point Likert-type scale. MPS was administered to 617 first year students at the university of Liège (table II). Differences are considered according to gender and experience of failure i.e. the fact of repeating an academic year. We realized a component analysis with promax rotation. Among the different possibilities offered by the scree-test the choice of a 4 factor solution stresses the original structure: SOP (14 items), SPP (12 items), OOP (9 items) and anti OOP (10 items); the last one is additional but allows for respecting semantics and saturation of the items. The first aim of confirming validity and internal consistency is satisfactory. In other respects the multidimensional structure of the concept leads to consideration of a positive, adaptive perfectionism and a more negative perfectionism, facilitating psychopathology (59, 60, 61). So it seems interesting to compare the different components of MPS in order to find an eventual sex-failure effect. The evaluation of perfectionism is obvious, considering it as a personality

  6. [Failure effects and gender differences in perfectionism].

    PubMed

    Masson, A M; Cadot, M; Ansseau, M

    2003-01-01

    perfectionism are described: SOP (Self Oriented Perfectionism) related to high standards and self criticism, SPP (Socially Prescribed Perfectionism) related to the need of approval from others and fear of negative evaluation, OOP (Other-Oriented Perfectionism) reflecting a tendency to set high expectations for others and to evaluate them in a demanding way; this component is related, especially for males, to self-esteem, hostility and authoritarianism. Validity and internal consistency have been established too (30, 31, 35). The Frost and al's Multidimensional Perfectionism Scale and the Hewitt and Flett's scales are closely associated, except concerning the OOP. Because this component could provide new information, we have chosen the second scale, referring to the French translation and validation of Labrecque (45). EMP is the French name of MPS; it is a self-report questionnaire of 45 questions, in fact three subscales of 15 items rated on a 7-point Likert-type scale. MPS was administered to 617 first year students at the university of Liège (table II). Differences are considered according to gender and experience of failure i.e. the fact of repeating an academic year. We realized a component analysis with promax rotation. Among the different possibilities offered by the scree-test the choice of a 4 factor solution stresses the original structure: SOP (14 items), SPP (12 items), OOP (9 items) and anti OOP (10 items); the last one is additional but allows for respecting semantics and saturation of the items. The first aim of confirming validity and internal consistency is satisfactory. In other respects the multidimensional structure of the concept leads to consideration of a positive, adaptive perfectionism and a more negative perfectionism, facilitating psychopathology (59, 60, 61). So it seems interesting to compare the different components of MPS in order to find an eventual sex-failure effect. The evaluation of perfectionism is obvious, considering it as a personality

  7. A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems

    SciTech Connect

    Wan, Lipeng; Wang, Feiyi; Oral, H. Sarp; Vazhkudai, Sudharshan S.; Cao, Qing

    2014-11-01

    High-performance computing (HPC) storage systems provide data availability and reliability using various hardware and software fault tolerance techniques. Usually, reliability and availability are calculated at the subsystem or component level using limited metrics such as, mean time to failure (MTTF) or mean time to data loss (MTTDL). This often means settling on simple and disconnected failure models (such as exponential failure rate) to achieve tractable and close-formed solutions. However, such models have been shown to be insufficient in assessing end-to-end storage system reliability and availability. We propose a generic simulation framework aimed at analyzing the reliability and availability of storage systems at scale, and investigating what-if scenarios. The framework is designed for an end-to-end storage system, accommodating the various components and subsystems, their interconnections, failure patterns and propagation, and performs dependency analysis to capture a wide-range of failure cases. We evaluate the framework against a large-scale storage system that is in production and analyze its failure projections toward and beyond the end of lifecycle. We also examine the potential operational impact by studying how different types of components affect the overall system reliability and availability, and present the preliminary results

  8. Failure-dependent test, repair, and shutdown strategies: Reducing the impact of common-cause failures

    SciTech Connect

    Uryasev, S.P.; Samanta, P.K.

    1996-11-01

    Failure-dependent testing implies a test of redundant components (or trains) when the failure of one component has been detected. The purpose of such testing is to detect any common-cause failures (CCFs) of multiple components so that a corrective action, such as repair or plant shutdown, can be taken to reduce the residence time of multiple failures. This type of testing focuses on reducing the conditional risk of CCFs. Formulas are developed for calculating the conditional failure probability of a two-train system with different test, repair, and shutdown strategies. A methodology is presented, with an example calculation, showing the risk effectiveness of failure-dependent strategies for emergency diesel generators in nuclear power plants. Four alternative actions after the identification of a failure of one component are analyzed: (a) not carrying out any additional testing, (b) testing the redundant components and shutting down the plant if a CCF is present, (c) emergency repair of the failed component in a given time (less than the allowed outage time), and (d) additional testing of redundant components after the repair of the failed component.

  9. Multi-Atlas Library for Eliminating Normalization Failures in Non-Human Primates.

    PubMed

    Maldjian, Joseph A; Shively, Carol A; Nader, Michael A; Friedman, David P; Whitlow, Christopher T

    2016-04-01

    Current tools for automated skull stripping, normalization, and segmentation of non-human primate (NHP) brain MRI studies typically demonstrate high failure rates. Many of these failures are due to a poor initial estimate for the affine component of the transformation. The purpose of this study is to introduce a multi-atlas approach to overcome these limitations and drive the failure rate to near zero. A library of study-specific templates (SST) spanning three Old World primate species (Macaca fascicularis, M. mulatta, Chlorocebus aethiops) was created using a previously described unbiased automated approach. Several modifications were introduced to the methodology to improve initial affine estimation at the study-specific template level, and at the individual subject level. These involve performing multiple separate normalizations to a multi-atlas library of templates and selecting the best performing template on the basis of a covariance similarity metric. This template was then used as an initialization for the affine component of subsequent skull stripping and normalization procedures. Normalization failure rate for SST generation and individual-subject segmentation on a set of 150 NHP was evaluated on the basis of visual inspection. The previous automated template creation procedure results in excellent skull stripping, segmentation, and atlas labeling across species. Failure rate at the individual-subject level was approximately 1%, however at the SST generation level it was 17%. Using the new multi-atlas approach, failure rate was further reduced to zero for both SST generation and individual subject processing. We describe a multi-atlas library registration approach for driving normalization failures in NHP to zero. It is straightforward to implement, and can have application to a wide variety of existing tools, as well as in difficult populations including neonates and the elderly. This approach is also an important step towards developing fully automated

  10. Development of a clinical prediction rule to improve peripheral intravenous cannulae first attempt success in the emergency department and reduce post insertion failure rates: the Vascular Access Decisions in the Emergency Room (VADER) study protocol

    PubMed Central

    Carr, Peter J; Rippey, James C R; Cooke, Marie L; Bharat, Chrianna; Murray, Kevin; Higgins, Niall S; Foale, Aileen; Rickard, Claire M

    2016-01-01

    Introduction Peripheral intravenous cannula (PIVC) insertion is one of the most common clinical interventions performed in emergency care worldwide. However, factors associated with successful PIVC placement and maintenance are not well understood. This study seeks to determine the predictors of first time PIVC insertion success in emergency department (ED) and identify the rationale for removal of the ED inserted PIVC in patients admitted to the hospital ward. Reducing failed insertion attempts and improving peripheral intravenous cannulation practice could lead to better staff and patient experiences, as well as improving hospital efficiency. Methods and analysis We propose an observational cohort study of PIVC insertions in a patient population presenting to ED, with follow-up observation of the PIVC in subsequent admissions to the hospital ward. We will collect specific PIVC observational data such as; clinician factors, patient factors, device information and clinical practice variables. Trained researchers will gather ED PIVC insertion data to identify predictors of insertion success. In those admitted from the ED, we will determine the dwell time of the ED-inserted PIVC. Multivariate regression analyses will be used to identify factors associated with insertions success and PIVC failure and standard statistical validation techniques will be used to create and assess the effectiveness of a clinical predication rule. Ethics and dissemination The findings of our study will provide new evidence to improve insertion success rates in the ED setting and identify strategies to reduce premature device failure for patients admitted to hospital wards. Results will unravel a complexity of factors that contribute to unsuccessful PIVC attempts such as patient and clinician factors along with the products, technologies and infusates used. Trial registration number ACTRN12615000588594; Pre-results. PMID:26868942

  11. NESTEM-QRAS: A Tool for Estimating Probability of Failure

    NASA Technical Reports Server (NTRS)

    Patel, Bhogilal M.; Nagpal, Vinod K.; Lalli, Vincent A.; Pai, Shantaram; Rusick, Jeffrey J.

    2002-01-01

    An interface between two NASA GRC specialty codes, NESTEM and QRAS has been developed. This interface enables users to estimate, in advance, the risk of failure of a component, a subsystem, and/or a system under given operating conditions. This capability would be able to provide a needed input for estimating the success rate for any mission. NESTEM code, under development for the last 15 years at NASA Glenn Research Center, has the capability of estimating probability of failure of components under varying loading and environmental conditions. This code performs sensitivity analysis of all the input variables and provides their influence on the response variables in the form of cumulative distribution functions. QRAS, also developed by NASA, assesses risk of failure of a system or a mission based on the quantitative information provided by NESTEM or other similar codes, and user provided fault tree and modes of failure. This paper will describe briefly, the capabilities of the NESTEM, QRAS and the interface. Also, in this presentation we will describe stepwise process the interface uses using an example.

  12. Diastolic heart failure.

    PubMed

    Gary, Rebecca; Davis, Leslie

    2008-01-01

    Diastolic heart failure (DHF) is estimated to occur in 40% to 50% of patients with heart failure. Evidence suggests that DHF is primarily a cardiogeriatric syndrome that increases from approximately 1% at age 50 years to 10% or more at 80 years. DHF is also more likely to occur in older women who are hypertensive or diabetic. Although survival is better in patients with DHF compared with systolic heart failure, mortality rates for patients with DHF are four times higher than those for healthy, community-dwelling older adults. The increase in DHF is anticipated to continue during the next several decades largely because of the aging of the population; increase in risk factors associated with hypertension, diabetes, and obesity; and ongoing technologic advances in the treatment of cardiovascular disease. Few clinical trials have evaluated therapy in this population, so evidence about the effectiveness of treatment strategies for DHF is limited. Future research should target novel interventions that specifically target patients with DHF who are typically older and female, and experience exertional intolerance and have a considerably reduced quality of life.

  13. Acute kidney failure

    MedlinePlus

    Kidney failure; Renal failure; Renal failure - acute; ARF; Kidney injury - acute ... There are many possible causes of kidney damage. They include: ... cholesterol (cholesterol emboli) Decreased blood flow due to very ...

  14. What Is Heart Failure?

    MedlinePlus

    ... page from the NHLBI on Twitter. What Is Heart Failure? Heart failure is a condition in which the heart can' ... force. Some people have both problems. The term "heart failure" doesn't mean that your heart has stopped ...

  15. New medications for heart failure.

    PubMed

    Gordin, Jonathan S; Fonarow, Gregg C

    2016-08-01

    Heart failure is common and results in substantial morbidity and mortality. Current guideline-based therapies for heart failure with reduced ejection fraction, including beta blockers, angiotensin converting enzyme (ACE) inhibitors, and aldosterone antagonists aim to interrupt deleterious neurohormonal pathways and have shown significant success in reducing morbidity and mortality associated with heart failure. Continued efforts to further improve outcomes in patients with heart failure with reduced ejection fraction have led to the first new-in-class medications approved for heart failure since 2005, ivabradine and sacubitril/valsartan. Ivabradine targets the If channels in the sinoatrial node of the heart, decreasing heart rate. Sacubitril/valsartan combines a neprilysin inhibitor that increases levels of beneficial vasodilatory peptides with an angiotensin receptor antagonist. On a background of previously approved, guideline-directed medical therapies for heart failure, these medications have shown improved clinical outcomes ranging from decreased hospitalizations in a select group of patients to a reduction in all-cause mortality across all pre-specified subgroups. In this review, we will discuss the previously established guideline-directed medical therapies for heart failure with reduced ejection fraction, the translational research that led to the development of these new therapies, and the results from the major clinical trials of ivabradine and sacubitril/valsartan. PMID:27038558

  16. Failure and Life Cycle Evaluation of Watering Valves

    PubMed Central

    Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

    2011-01-01

    Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves’ internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a ‘drying out’ period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure. PMID:22330720

  17. Heart failure - medicines

    MedlinePlus

    CHF - medicines; Congestive heart failure - medicines; Cardiomyopathy - medicines; HF - medicines ... You will need to take most of your heart failure medicines every day. Some medicines are taken ...

  18. Enhanced Component Performance Study: Emergency Diesel Generators 1998–2014

    SciTech Connect

    Schroeder, John Alton

    2015-11-01

    This report presents an enhanced performance evaluation of emergency diesel generators (EDGs) at U.S. commercial nuclear power plants. This report evaluates component performance over time using (1) Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES) data from 1998 through 2014 and (2) maintenance unavailability (UA) performance data from Mitigating Systems Performance Index (MSPI) Basis Document data from 2002 through 2014. The objective is to show estimates of current failure probabilities and rates related to EDGs, trend these data on an annual basis, determine if the current data are consistent with the probability distributions currently recommended for use in NRC probabilistic risk assessments, show how the reliability data differ for different EDG manufacturers and for EDGs with different ratings; and summarize the subcomponents, causes, detection methods, and recovery associated with each EDG failure mode. Engineering analyses were performed with respect to time period and failure mode without regard to the actual number of EDGs at each plant. The factors analyzed are: sub-component, failure cause, detection method, recovery, manufacturer, and EDG rating. Six trends with varying degrees of statistical significance were identified in the data.

  19. Analysis of Emergency Diesel Generators Failure Incidents in Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Hunt, Ronderio LaDavis

    In early years of operation, emergency diesel generators have had a minimal rate of demand failures. Emergency diesel generators are designed to operate as a backup when the main source of electricity has been disrupted. As of late, EDGs (emergency diesel generators) have been failing at NPPs (nuclear power plants) around the United States causing either station blackouts or loss of onsite and offsite power. These failures occurred from a specific type called demand failures. This thesis evaluated the current problem that raised concern in the nuclear industry which was averaging 1 EDG demand failure/year in 1997 to having an excessive event of 4 EDG demand failure year which occurred in 2011. To determine the next occurrence of the extreme event and possible cause to an event of such happening, two analyses were conducted, the statistical and root cause analysis. Considering the statistical analysis in which an extreme event probability approach was applied to determine the next occurrence year of an excessive event as well as, the probability of that excessive event occurring. Using the root cause analysis in which the potential causes of the excessive event occurred by evaluating, the EDG manufacturers, aging, policy changes/ maintenance practices and failure components. The root cause analysis investigated the correlation between demand failure data and historical data. Final results from the statistical analysis showed expectations of an excessive event occurring in a fixed range of probability and a wider range of probability from the extreme event probability approach. The root-cause analysis of the demand failure data followed historical statistics for the EDG manufacturer, aging and policy changes/ maintenance practices but, indicated a possible cause regarding the excessive event with the failure components. Conclusions showed the next excessive demand failure year, prediction of the probability and the next occurrence year of such failures, with an

  20. Steam generator tube failures

    SciTech Connect

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  1. Foam failure

    NASA Astrophysics Data System (ADS)

    Staicu, Adrian Daniel; Hilgenfeldt, Sascha

    2004-11-01

    We create finger-like patterns by forcing air into 2D aqueous foams in a Hele-Shaw rectangular channel. For moderate values of the gas flow rate, zipper-shaped patterns advance steadily through mono-disperse foam, occupying a constant fraction λt of the channel width. The small-scale foam structure is simultaneously recorded using high-speed imaging, giving us direct access to the dynamics of individual Plateau borders. We establish that the advance of the tip region is similar to that of a crack in a ductile solid, an idea confirmed by the strong localization of the elastic stress. An energy budget shows that dissipative effects (particularly viscous friction of the Plateau borders against the channel plates) dominate elastic storage of energy. In the limit where λt becomes comparable to the cell size, viscous dissipation is insufficient to balance the energy input from the supply of air. The system then exhibits a transition to the analog of a brittle crack, where bursting soap-films play the role of broken atomic bonds. The brittle crack speed is comparable to that of waves in foam.

  2. Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates of Bacteria on Mars Landers

    NASA Technical Reports Server (NTRS)

    Schuerger, Andrew C.; Kern, Roger G.

    2004-01-01

    In order to minimize the forward contamination of Mars, spacecraft are assembled under cleanroom conditions that require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival on the surface of Mars by protecting spores from sterilizing agents, including UV irradiation. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

  3. Development of A Tabulated Thermo-Viscoplastic Material Model with Regularized Failure for Dynamic Ductile Failure Prediction of Structures under Impact Loading

    NASA Astrophysics Data System (ADS)

    Buyuk, Murat

    -of-stress, strain-rate and temperature. Regularization treatment is implemented to reduce mesh size dependency especially for the problems where softening and failure is involved for the failure prediction. Ductile deformation and failure mechanism of 2024-T3/T351 aluminum alloy is investigated experimentally and numerically for quasi-static and dynamic conditions at various temperatures and stress-states. An intelligently contrived test matrix is developed by designing specific test specimens with different geometries that can construct a failure locus as a function of state-of-stress, strain-rate and temperature. An inverse material characterization algorithm is then introduced to generate input data for the new material model. Tabulated inputs of characterized material test results are directly used for both the constitutive and failure treatment of the new material model. Component based specimen tests that are used to characterize the material input properties and full-scale impact tests that are performed at different target thicknesses and impact speeds are used to validate and show the robustness, accuracy and efficiency of the new material model. It is shown that the new material model is capable of predicting ballistic limit and failure modes accurately for structures under impact even if the failure mode changes drastically. It is also shown that the new regularization model provides less mesh size dependency. These associated features of the model suggest that the new material model can be used as a promising generic tool for diverse applications of dynamic ductile deformation and failure phenomenon.

  4. Advanced Heart Failure

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Advanced Heart Failure Updated:Oct 8,2015 When heart failure (HF) ... content was last reviewed on 04/06/2015. Heart Failure • Home • About Heart Failure • Causes and Risks for ...

  5. Seasonal factors influencing the failure of buried water reticulation pipes.

    PubMed

    Gould, S J F; Boulaire, F A; Burn, S; Zhao, X L; Kodikara, J K

    2011-01-01

    While the use of environmental factors in the analysis and prediction of failures of buried reticulation pipes in cold environments has been the focus of extensive work, the same cannot be said for failures occurring on pipes in other (non-freezing) environments. A novel analysis of pipe failures in such an environment is the subject of this paper. An exploratory statistical analysis was undertaken, identifying a peak in failure rates during mid to late summer. This peak was found to correspond to a peak in the rate of circumferential failures, whilst the rate of longitudinal failures remained constant. Investigation into the effect of climate on failure rates revealed that the peak in failure rates occurs due to differential soil movement as the result of shrinkage in expansive soils. PMID:22049766

  6. Heart Failure Update: Chronic Disease Management Programs.

    PubMed

    Fountain, Lorna B

    2016-03-01

    With high mortality and readmission rates among patients with heart failure (HF), multiple disease management models have been and continue to be tested, with mixed results. Early postdischarge care improves outcomes for patients. Telemonitoring also can assist in reducing mortality and HF-related hospitalizations. Office-based team care improves patient outcomes, with important components including rapid access to physicians, partnerships with clinical pharmacists, education, monitoring, and support. Pay-for-performance measures developed for HF, primarily use of angiotensin-converting enzyme inhibitors and beta blockers, also improve patient outcomes, but the influence of adherence to other measures has been minimal. Evaluating comorbid conditions, including diabetes and hypertension, and making drug adjustments for patients with HF to include blood pressure control and use of metformin, when possible, can reduce mortality and morbidity. PMID:26974003

  7. Heart Failure Update: Chronic Disease Management Programs.

    PubMed

    Fountain, Lorna B

    2016-03-01

    With high mortality and readmission rates among patients with heart failure (HF), multiple disease management models have been and continue to be tested, with mixed results. Early postdischarge care improves outcomes for patients. Telemonitoring also can assist in reducing mortality and HF-related hospitalizations. Office-based team care improves patient outcomes, with important components including rapid access to physicians, partnerships with clinical pharmacists, education, monitoring, and support. Pay-for-performance measures developed for HF, primarily use of angiotensin-converting enzyme inhibitors and beta blockers, also improve patient outcomes, but the influence of adherence to other measures has been minimal. Evaluating comorbid conditions, including diabetes and hypertension, and making drug adjustments for patients with HF to include blood pressure control and use of metformin, when possible, can reduce mortality and morbidity.

  8. Analyzing failures: the problems and the solutions

    SciTech Connect

    Goel, V.S.

    1986-01-01

    Papers are presented on a failure analysis of a large centrifugal blower, field fractures in heavy equipment, a failure analysis of a liquid propane gas cylinder, an analysis of helicopter blade fatigue fracture by digital fractographic imaging analysis, and the influence of failure analyses on materials technology and design. Also considered are an analysis of aircraft component failures, the growth of short cracks in IN718, the improper fabrication of rotating blades (resulting in premature failure), and low cycle thermal fatigue and fracture of reinforced piping. Other topics include a nonlinear finite element analysis of stress concentration at high temperature, the inelastic analysis of a hot spot on a heavy vessel wall, the accuracy and precision of mechanical test data generated using computerized testing systems, and maintenance related failures.

  9. Failure analysis issues in microelectromechanical systems (MEMS).

    SciTech Connect

    Walraven, Jeremy Allen

    2005-07-01

    Failure analysis and device characterization of MEMS components are critical steps in understanding the root causes of failure and improving device performance. At the wafer and die level these tasks can be performed with little or no sample preparation. Larger challenges occur after fabrication when the device is packaged, capped, sealed, or otherwise obstructed from view. The challenges and issues of MEMS failure analysis lie in identifying the root cause of failure for these packaged, capped, and sealed devices without perturbing the device or its immediate environment. Novel methods of gaining access to the device or preparing the device for analysis are crucial to accurately determining the root cause of failure. This paper will discuss issues identified in performing root cause failure analysis of packaged MEMS devices, as well as the methods employed to analyze them.

  10. Prognostics for Microgrid Components

    NASA Technical Reports Server (NTRS)

    Saxena, Abhinav

    2012-01-01

    Prognostics is the science of predicting future performance and potential failures based on targeted condition monitoring. Moving away from the traditional reliability centric view, prognostics aims at detecting and quantifying the time to impending failures. This advance warning provides the opportunity to take actions that can preserve uptime, reduce cost of damage, or extend the life of the component. The talk will focus on the concepts and basics of prognostics from the viewpoint of condition-based systems health management. Differences with other techniques used in systems health management and philosophies of prognostics used in other domains will be shown. Examples relevant to micro grid systems and subsystems will be used to illustrate various types of prediction scenarios and the resources it take to set up a desired prognostic system. Specifically, the implementation results for power storage and power semiconductor components will demonstrate specific solution approaches of prognostics. The role of constituent elements of prognostics, such as model, prediction algorithms, failure threshold, run-to-failure data, requirements and specifications, and post-prognostic reasoning will be explained. A discussion on performance evaluation and performance metrics will conclude the technical discussion followed by general comments on open research problems and challenges in prognostics.

  11. Influence of central neurotransmitters on heart rate variability in outbred rats at rest and during acute stress: nature of very-low-wave spectrum component revisited.

    PubMed

    Kurjanova, E V; Teplyj, D L

    2010-07-01

    We studied the effect of blockade of neurotransmitter monoamine reuptake and inhibition of catecholamine synthesis on heart rate variability in outbred albino rats at rest and during acute stress. Amitriptyline increased, while α-methyltyrosine reduced the power of VLF waves in heart rate variability spectrum. The effect of amitriptyline manifested at rest and was most striking under stressful conditions, while the effect of α-methyltyrosine was observed only under conditions of acute stress. This suggests that VLF-band waves in the heart rate variability spectrum have catecholaminergic nature and are determined by activity of the central monoaminergic systems; the role of peripheral adrenergic influences mediated by humoral and nervous regulation in the formation of these waves cannot also be excluded.

  12. Bond failure patterns in vivo.

    PubMed

    Linklater, Rognvald A; Gordon, Peter H

    2003-05-01

    The aim of this study was to identify the presence and pattern of differences in bond failure between tooth types in vivo when bonding orthodontic brackets with the no-mix orthodontic composite adhesive Right-On. In vivo bond failure for a single operator was recorded for 108 consecutive patients undergoing fixed-appliance orthodontic treatment. The bond failure data were analyzed by survival analysis. Time to first failure or censorship was recorded for each bonded attachment. Overall failure in the sample matched previous clinical studies but conflicted with previous ex vivo bond strength data. Mandibular and posterior teeth had significantly higher rates of failure than did maxillary and anterior teeth. The type of attachment used had a significant effect on bond survival. The results of this study confirm that in vivo bond survival is not uniform for all teeth. Comparisons between the findings of this study and those of a previous ex vivo study by the same authors failed to validate ex vivo bond strength testing as clinically relevant.

  13. Development of ProCaRS Clinical Nomograms for Biochemical Failure-free Survival Following Either Low-Dose Rate Brachytherapy or Conventionally Fractionated External Beam Radiation Therapy for Localized Prostate Cancer

    PubMed Central

    Warner, Andrew; Pickles, Tom; Crook, Juanita; Martin, Andre-Guy; Souhami, Luis; Catton, Charles; Lukka, Himu

    2015-01-01

    Purpose: Although several clinical nomograms predictive of biochemical failure-free survival (BFFS) for localized prostate cancer exist in the medical literature, making valid comparisons can be challenging due to variable definitions of biochemical failure, the disparate distribution of prognostic factors, and received treatments in patient populations. The aim of this investigation was to develop and validate clinically-based nomograms for 5-year BFFS using the ASTRO II “Phoenix” definition for two patient cohorts receiving low-dose rate (LDR) brachytherapy or conventionally fractionated external beam radiation therapy (EBRT) from a large Canadian multi-institutional database. Methods and Materials: Patients were selected from the GUROC (Genitourinary Radiation Oncologists of Canada) Prostate Cancer Risk Stratification (ProCaRS) database if they received (1) LDR brachytherapy ≥ 144 Gy (n=4208) or (2) EBRT ≥ 70 Gy  (n=822). Multivariable Cox regression analysis for BFFS was performed separately for each cohort and used to generate clinical nomograms predictive of 5-year BFFS. Nomograms were validated using calibration plots of nomogram predicted probability versus observed probability via Kaplan-Meier estimates. Results: Patients receiving LDR brachytherapy had a mean age of 64 ± 7 years, a mean baseline PSA of 6.3 ± 3.0 ng/mL, 75% had a Gleason 6, and 15% had a Gleason 7, whereas patients receiving EBRT had a mean age of 70 ± 6 years, a mean baseline PSA of 11.6 ± 10.7 ng/mL, 30% had a Gleason 6, 55% had a Gleason 7, and 14% had a Gleason 8-10. Nomograms for 5-year BFFS included age, use and duration of androgen deprivation therapy (ADT), baseline PSA, T stage, and Gleason score for LDR brachytherapy and an ADT (months), baseline PSA, Gleason score, and biological effective dose (Gy) for EBRT. Conclusions: Clinical nomograms examining 5-year BFFS were developed for patients receiving either LDR brachytherapy or conventionally fractionated EBRT and

  14. The failure-tolerant leader.

    PubMed

    Farson, Richard; Keyes, Ralph

    2002-08-01

    "The fastest way to succeed," IBM's Thomas Watson, Sr., once said, "is to double your failure rate." In recent years, more and more executives have embraced Watson's point of view, coming to understand what innovators have always known: Failure is a prerequisite to invention. But while companies may grasp the value of making mistakes at the level of corporate practices, they have a harder time accepting the idea at the personal level. People are afraid to fail, and corporate culture reinforces that fear. In this article, psychologist and former Harvard Business School professor Richard Farson and coauthor Ralph Keyes discuss how companies can reduce the fear of miscues. What's crucial is the presence of failure-tolerant leaders--executives who, through their words and actions, help employees overcome their anxieties about making mistakes and, in the process, create a culture of intelligent risk-taking that leads to sustained innovation. Such leaders don't just accept productive failure, they promote it. Drawing from their research in business, politics, sports, and science, the authors identify common practices among failure-tolerant leaders. These leaders break down the social and bureaucratic barriers that separate them from their followers. They engage at a personal level with the people they lead. They avoid giving either praise or criticism, preferring to take a nonjudgmental, analytical posture as they interact with staff. They openly admit their own mistakes rather than trying to cover them up or shifting the blame. And they try to root out the destructive competitiveness built into most organizations. Above all else, failure-tolerant leaders push people to see beyond traditional definitions of success and failure. They know that as long as a person views failure as the opposite of success, rather than its complement, he or she will never be able to take the risks necessary for innovation. PMID:12195921

  15. Cardiac effects of the extract and active components of radix stephaniae tetrandrae. II. Myocardial infarct, arrhythmias, coronary arterial flow and heart rate in the isolated perfused rat heart.

    PubMed

    Yu, X C; Wu, S; Wang, G Y; Shan, J; Wong, T M; Chen, C F; Pang, K T

    2001-05-11

    The primary purpose of the present study was to compare the cardioprotective effects of the extract from radix stephaniae tetrandrae (RST) and its individual compounds, tetrandrine (Tet) and fanchinoline (Fan). Secondly, we also compared the cardiac effects of the individual compounds and the RST extract with those of verapamil, a classical Ca2+ channel blocker. The Langendorff isolated perfused rat heart preparation was used. Regional ischaemia and reperfusion was employed to induce myocardial infarct and arrhythmia. Infarct, arrhythmia, heart rate and coronary artery flow were determined in hearts treated with vehicle, RST extract, Tet, Fan, or verapamil. It was found that RST extract, of which only 9% was Tet, and Tet alone produced equally potent ameliorating effects on arrhythmia and infarct induced by ischaemia and reperfusion without further inhibiting ischaemia-reduced heart rate and coronary artery flow. Fan had no effects on arrhythmia and infarct induced by ischaemia and reperfusion; but it induced S-T segment elevation and further reduced heart rate and coronary artery flow during ischaemia. Verapamil also ameliorated the effects of ischaemia and reperfusion on arrhythmia and infarct. It should be noted that 1 microM verapamil, that produced comparable effects on infarct and arrhythmia to the RST extract and Tet, further inhibited heart rate during ischaemia. The results indicate that the RST extract produces equally potent cardioprotective and anti-arrhythmic effects as Tet alone. Both RST extract and Tet may be better choices for the treatment of arrhythmia and infarct induced by myocardial ischaemia and reperfusion than the classical Ca2+ channel blocker, verapamil as they do not further reduce heart rate during ischaemia. PMID:11432452

  16. Renal failure in Yemen.

    PubMed

    Al-Rohani, M

    2004-01-01

    Renal failure remains a serious cause of mortality in Yemen. Our region has 1.25 million population and our hospital is the central hospital, which has a nephrology department and performs dialysis for the region. Between January 1998 and December 2002, we admitted 547 patients; including children, with acute renal failure (ARF) and chronic renal failure (CRF). CRF was observed in 400 patients, an incidence of 64 per million per year and a prevalence of 320 per million. ARF occurred in 147 persons with an incidence of 23.5 per million per year and a prevalence of 117.5 patients per million. Of all patients, 72% were adults (age range, 20-60 years) with a male preponderance. As a tropical country, malaria (27.9%), diarrhea (13.6%), and other infectious diseases were the main causes. Next most common were obstructive diseases causing CRF and ARF (26.8% and 12.9%, respectively), mainly urolithiasis, Schistosomiasis, and prostatic enlargement. However the cause of CRF in 57.5% of patients was unknown as most persons presented late with end-stage disease (64.7%), requiring immediate intervention. Other causes, such as hepatorenal syndrome, snake bite, diabetes mellitus, and hypertension, showed low occurrence rates. Patients presented to the hospital mostly in severe uremia and without a clear history of prior medications. The major findings were vomiting, acidosis, and hypertension with serum creatinine values ranging between 2.8-45 mg/dL (mean value, 13.4 mg/dL). Anemia was observed in 80.4% of CRF versus 62.6% of ARF patients. Hypertension prevalence was 65.5% among CRF patients, of whom 25% were in hypertensive crisis, whereas among ARF the prevalence was only 26.5%. PMID:15350475

  17. Enhanced Droplet Erosion Resistance of Laser Treated Nano Structured TWAS and Plasma Ion Nitro-Carburized Coatings for High Rating Steam Turbine Components

    NASA Astrophysics Data System (ADS)

    Pant, B. K.; Arya, Vivek; Mann, B. S.

    2010-09-01

    This article deals with surface modification of twin wire arc sprayed (TWAS) and plasma ion nitro-carburized X10CrNiMoV1222 steel using high power diode laser (HPDL) to overcome water droplet erosion occurring in low pressure steam turbine (LPST) bypass valves and LPST moving blades used in high rating conventional, critical, and super critical thermal power plants. The materials commonly used for high rating steam turbines blading are X10CrNiMoV1222 steel and Ti6Al4V titanium alloy. The HPDL surface treatment on TWAS coated X10CrNiMoV1222 steel as well as on plasma ion nitro-carburized steel has improved water droplet resistance manifolds. This may be due to combination of increased hardness and toughness as well as the formation of fine grained structure due to rapid heating and cooling rates associated with the laser surface treatment. The water droplet erosion test results along with their damage mechanism are reported in this article.

  18. Components of Particle Emissions from Light-Duty Spark-Ignition Vehicles with Varying Aromatic Content and Octane Rating in Gasoline.

    PubMed

    Short, Daniel Z; Vu, Diep; Durbin, Thomas D; Karavalakis, Georgios; Asa-Awuku, Akua

    2015-09-01

    Typical gasoline consists of varying concentrations of aromatic hydrocarbons and octane ratings. However, their impacts on particulate matter (PM) such as black carbon (BC) and water-soluble and insoluble particle compositions are not well-defined. This study tests seven 2012 model year vehicles, which include one port fuel injection (PFI) configured hybrid vehicle, one PFI vehicle, and six gasoline direct injection (GDI) vehicles. Each vehicle was driven on the Unified transient testing cycle (UC) using four different fuels. Three fuels had a constant octane rating of 87 with varied aromatic concentrations at 15%, 25%, and 35%. A fourth fuel with higher octane rating, 91, contained 35% aromatics. BC, PM mass, surface tension, and water-soluble organic mass (WSOM) fractions were measured. The water-insoluble mass (WIM) fraction of the vehicle emissions was estimated. Increasing fuel aromatic content increases BC emission factors (EFs) of transient cycles. BC concentrations were higher for the GDI vehicles than the PFI and hybrid vehicles, suggesting a potential climate impact for increased GDI vehicle production. Vehicle steady-state testing showed that the hygroscopicity of PM emissions at high speeds (70 mph; κ > 1) are much larger than emissions at low speeds (30 mph; κ < 0.1). Iso-paraffin content in the fuels was correlated to the decrease in WSOM emissions. Both aromatic content and vehicle speed increase the amount of hygroscopic material found in particle emissions. PMID:26244891

  19. Components of Particle Emissions from Light-Duty Spark-Ignition Vehicles with Varying Aromatic Content and Octane Rating in Gasoline.

    PubMed

    Short, Daniel Z; Vu, Diep; Durbin, Thomas D; Karavalakis, Georgios; Asa-Awuku, Akua

    2015-09-01

    Typical gasoline consists of varying concentrations of aromatic hydrocarbons and octane ratings. However, their impacts on particulate matter (PM) such as black carbon (BC) and water-soluble and insoluble particle compositions are not well-defined. This study tests seven 2012 model year vehicles, which include one port fuel injection (PFI) configured hybrid vehicle, one PFI vehicle, and six gasoline direct injection (GDI) vehicles. Each vehicle was driven on the Unified transient testing cycle (UC) using four different fuels. Three fuels had a constant octane rating of 87 with varied aromatic concentrations at 15%, 25%, and 35%. A fourth fuel with higher octane rating, 91, contained 35% aromatics. BC, PM mass, surface tension, and water-soluble organic mass (WSOM) fractions were measured. The water-insoluble mass (WIM) fraction of the vehicle emissions was estimated. Increasing fuel aromatic content increases BC emission factors (EFs) of transient cycles. BC concentrations were higher for the GDI vehicles than the PFI and hybrid vehicles, suggesting a potential climate impact for increased GDI vehicle production. Vehicle steady-state testing showed that the hygroscopicity of PM emissions at high speeds (70 mph; κ > 1) are much larger than emissions at low speeds (30 mph; κ < 0.1). Iso-paraffin content in the fuels was correlated to the decrease in WSOM emissions. Both aromatic content and vehicle speed increase the amount of hygroscopic material found in particle emissions.

  20. The comparative study of five sex-determining proteins across insects unveils high rates of evolution at basal components of the sex determination cascade.

    PubMed

    Eirín-López, José M; Sánchez, Lucas

    2015-01-01

    In insects, the sex determination cascade is composed of genes that interact with each other in a strict hierarchical manner, constituting a coadapted gene complex built in reverse order from bottom to top. Accordingly, ancient elements at the bottom are expected to remain conserved ensuring the correct functionality of the cascade. In the present work, we have studied the levels of variation displayed by five key components of the sex determination cascade across 59 insect species, including Sex-lethal, transformer, transformer-2, fruitless, doublesex, and sister-of-Sex-lethal (a paralog of Sxl encompassing sex-independent functions). Surprisingly, our results reveal that basal components of the cascade (doublesex, fruitless) seem to evolve more rapidly than previously suspected. Indeed, in the case of Drosophila, these proteins evolve more rapidly than the master regulator Sex-lethal. These results agree with the notion suggesting that genes involved in early aspects of development will be more constrained due to the large deleterious pleiotropic effects of mutations, resulting in increased levels of purifying selection at top positions of the cascade. The analyses of the selective episodes involved in the recruitment of Sxl into sex-determining functions further support this idea, suggesting the presence of bursts of adaptive selection in the common ancestor of drosophilids, followed by the onset of purifying selection preserving the master regulatory role of this protein on top of the Drosophila sex determination cascade. Altogether, these results underscore the importance of the position of sex determining genes in the cascade, constituting a major constraint shaping the molecular evolution of the insect sex determination pathway.

  1. The consequences of expansion joint bellows failure

    SciTech Connect

    Miller, R.F.; Daugherty, W.L.

    1993-08-01

    Expansion joint (EJ) bellows are thin walled, flexible components of a piping system. As such, they usually are the weakest structural link in the pressure boundary from a failure probability perspective. Previously, a 360{degrees}, circumferential rupture of a bellows was conservatively assumed to cause bellows collapse due to internal pressure resulting in a double-ended guillotine break (DEGB) and the associated, large leak rate. A finite element analysis was performed to determine the structural response of a ruptured bellows and its ability to resist large opening areas and hence, large leak rates. The results show that a 360{degrees} break can lead to an opening width of up to 0.7 inch following an instantaneous rupture -- provided the equalizing rings and tie rods remain intact. This would result in an initial leak rate reduction equal to 80% of the previously assumed DEGB flow. The reduced flow rate is less than the water removal system capacity-assuring that flooding will not occur.

  2. Attributional Retraining: Reducing the Likelihood of Failure

    ERIC Educational Resources Information Center

    Haynes Stewart, Tara L.; Clifton, Rodney A.; Daniels, Lia M.; Perry, Raymond P.; Chipperfield, Judith G.; Ruthig, Joelle C.

    2011-01-01

    Failing a course is an acutely negative event for first-year university students, and a major contributor to high attrition rates at North American universities. Despite its prevalence, course failure receives relatively little research attention. What can be done to reduce course failure and help first-year students remain in university? This…

  3. Scaling of structural failure

    SciTech Connect

    Bazant, Z.P.; Chen, Er-Ping

    1997-01-01

    This article attempts to review the progress achieved in the understanding of scaling and size effect in the failure of structures. Particular emphasis is placed on quasibrittle materials for which the size effect is complicated. Attention is focused on three main types of size effects, namely the statistical size effect due to randomness of strength, the energy release size effect, and the possible size effect due to fractality of fracture or microcracks. Definitive conclusions on the applicability of these theories are drawn. Subsequently, the article discusses the application of the known size effect law for the measurement of material fracture properties, and the modeling of the size effect by the cohesive crack model, nonlocal finite element models and discrete element models. Extensions to compression failure and to the rate-dependent material behavior are also outlined. The damage constitutive law needed for describing a microcracked material in the fracture process zone is discussed. Various applications to quasibrittle materials, including concrete, sea ice, fiber composites, rocks and ceramics are presented.

  4. Telomeres and marrow failure.

    PubMed

    Calado, Rodrigo T

    2009-01-01

    Telomeres, repeat sequences at the ends of chromosomes, are protective chromosomal structures highly conserved from primitive organisms to humans. Telomeres inevitably shorten with every cell cycle, and telomere attrition has been hypothesized to be fundamental to normal senescence of cells, tissues, and organisms. Molecular mechanisms have evolved to maintain their length and protective function; telomerase (TERT) is a reverse transcriptase enzyme that uses an RNA molecule (TERC) as the template to elongate the 3' ends of telomeres. Shelterin is a collection of DNA-binding proteins that cover and protect telomeres. The recent discovery of inherited mutations in genes that function to repair telomeres as etiologic in a range of human diseases, which have clinical manifestations in diverse tissues, including the hematopoietic tissue, suggests that defects in telomere repair and protection can cause organ failure. Dyskeratosis congenita is the prototype of telomere diseases; it is characterized by bone marrow failure, mucocutaneous abnormalities, pulmonary fibrosis, liver cirrhosis, and increased susceptibility to cancer, including acute myeloid leukemia. Aplastic anemia, acute myeloid leukemia, and idiopathic pulmonary fibrosis also are associated with inherited mutations in telomere repair or protection genes. Additionally, telomere defects associate with predisposition to hematologic malignancy and epithelial tumors. Telomere erosion is abnormally rapid in patients with mutations in telomerase genes but also after hematopoietic stem cell transplant, and telomeres are naturally shorter in older individuals-all conditions associated with higher rates of malignant diseases. In human tissue culture, short telomeres produce end-to-end chromosome fusion, nonreciprocal translocations, and aneuploidy.

  5. Failure modes effects and criticality analysis (FMECA) approach to the crystalline silicon photovoltaic module reliability assessment

    NASA Astrophysics Data System (ADS)

    Kuitche, Joseph M.; Tamizh-Mani, Govindasamy; Pan, Rong

    2011-09-01

    Traditional degradation or reliability analysis of photovoltaic (PV) modules has historically consisted of some combination of accelerated stress and field testing, including field deployment and monitoring of modules over long time periods, and analyzing commercial warranty returns. This has been effective in identifying failure mechanisms and developing stress tests that accelerate those failures. For example, BP Solar assessed the long term reliability of modules deployed outdoor and modules returned from the field in 2003; and presented the types of failures observed. Out of about 2 million modules, the total number of returns over nine year period was only 0.13%. An analysis on these returns resulted that 86% of the field failures were due to corrosion and cell or interconnect break. These failures were eliminated through extended thermal cycling and damp heat tests. Considering that these failures are observed even on modules that have successfully gone through conventional qualification tests, it is possible that known failure modes and mechanisms are not well understood. Moreover, when a defect is not easily identifiable, the existing accelerated tests might no longer be sufficient. Thus, a detailed study of all known failure modes existed in field test is essential. In this paper, we combine the physics of failure analysis with an empirical study of the field inspection data of PV modules deployed in Arizona to develop a FMECA model. This technique examines the failure rates of individual components of fielded modules, along with their severities and detectabilities, to determine the overall effect of a defect on the module's quality and reliability.

  6. Team management of congestive heart failure across the continuum.

    PubMed

    Venner, G H; Seelbinder, J S

    1996-01-01

    Despite an increased incidence of congestive heart failure and frequency of hospital admissions for the Medicare population, there is little information available on improving outcomes for these patients. As changes in health care lead toward capitation, efficient care with limited use of expensive inpatient hospital resources is a necessity. The coordination of three critical components--inpatient, outpatient, and home care--can lead to positive outcomes in terms of functional capacity changes, length of stay, readmission rates, patient self-care knowledge, and patient satisfaction.

  7. Failure of endodontic treatment: The usual suspects

    PubMed Central

    Tabassum, Sadia; Khan, Farhan Raza

    2016-01-01

    Inappropriate mechanical debridement, persistence of bacteria in the canals and apex, poor obturation quality, over and under extension of the root canal filling, and coronal leakage are some of the commonly attributable causes of failure. Despite the high success rate of endodontic treatment, failures do occur in a large number of cases and most of the times can be attributed to the already stated causes. With an ever increasing number of endodontic treatments being done each day, it has become imperative to avoid or minimize the most fundamental of reasons leading to endodontic failure. This paper reviews the most common causes of endodontic failure along with radiographic examples. PMID:27011754

  8. Parts and Components Reliability Assessment: A Cost Effective Approach

    NASA Technical Reports Server (NTRS)

    Lee, Lydia

    2009-01-01

    System reliability assessment is a methodology which incorporates reliability analyses performed at parts and components level such as Reliability Prediction, Failure Modes and Effects Analysis (FMEA) and Fault Tree Analysis (FTA) to assess risks, perform design tradeoffs, and therefore, to ensure effective productivity and/or mission success. The system reliability is used to optimize the product design to accommodate today?s mandated budget, manpower, and schedule constraints. Stand ard based reliability assessment is an effective approach consisting of reliability predictions together with other reliability analyses for electronic, electrical, and electro-mechanical (EEE) complex parts and components of large systems based on failure rate estimates published by the United States (U.S.) military or commercial standards and handbooks. Many of these standards are globally accepted and recognized. The reliability assessment is especially useful during the initial stages when the system design is still in the development and hard failure data is not yet available or manufacturers are not contractually obliged by their customers to publish the reliability estimates/predictions for their parts and components. This paper presents a methodology to assess system reliability using parts and components reliability estimates to ensure effective productivity and/or mission success in an efficient manner, low cost, and tight schedule.

  9. In Support of Failure

    ERIC Educational Resources Information Center

    Carr, Allison

    2013-01-01

    In this essay, I propose a concerted effort to begin devising a theory and pedagogy of failure. I review the discourse of failure in Western culture as well as in composition pedagogy, ultimately suggesting that failure is not simply a judgement or indication of rank but is a relational, affect-bearing concept with tremendous relevance to…

  10. Ammonia tank failure

    SciTech Connect

    Sweat, M.E.

    1983-04-01

    An ammonia tank failure at Hawkeye Chemical of Clinton, Iowa is discussed. The tank was a double-wall, 27,000 metric-ton tank built in 1968 and commissioned in December 1969. The paper presented covers the cause of the failure, repair, and procedural changes made to prevent recurrence of the failure. (JMT)

  11. [The effect of various types of dry starch syrup on the rate of glucose utilization in lipid, carbohydrate, and protein components of rat liver].

    PubMed

    Antonova, Zh V; Virovets, O A; Gapparov, M M

    1994-01-01

    Effect of a diet, containing dextran maltose and dry starch syrup, on some patterns of liver tissue metabolism were studied in young Wistar rats within 30 days. The animals of Control Group 1 were kept on a diet containing corn starch as a source of carbohydrates; in Group 2 the starch was replaced by the dry starch syrup enriched with disaccharides and especially with maltose; the dry starch syrup added into the Group 3 diet containing mainly oligosaccharides and polymers with high levels of glucose residues. The label mixtures of 6-3N- and 6-14C-glucose as well as of 6-3H- and I-14C-glucose were administered into the animals on the day of death. Analysis of the findings has shown that the products of starch hydrolysis may the specific parameters of glucose metabolism. Incorporation of the label into liver tissue lipids was similar to the control values in the group of animals kept on a diet enriched with maltose as compared with group 3. The glycolytic pathway of glucose utilization was more activated than the pentosephosphate pathway after substituting starch for dry starch syrup as shown by differences in the rates of carbon incorporation at positions 1 and 6 of a glucose molecule.

  12. Khat Use: History and Heart Failure

    PubMed Central

    El-Menyar, Ayman; Mekkodathil, Ahammed; Al-Thani, Hassan; Al-Motarreb, Ahmed

    2015-01-01

    Recent reports suggest that 20 million people worldwide are regularly using khat as a stimulant, even though the habit of chewing khat is known to cause serious health issues. Historical evidence suggests khat use has existed since the 13th century in Ethiopia and the southwestern Arabian regions even before the cultivation and use of coffee. In the past three decades, its availability and use spread all over the world including the United States and Europe. Most of the consumers in the Western world are immigrant groups from Eastern Africa or the Middle East. The global transport and availability of khat has been enhanced by the development of synthetic forms of its active component. The World Health Organization considers khat a drug of abuse since it causes a range of health problems. However, it remains lawful in some countries. Khat use has long been a part of Yemeni culture and is used in virtually every social occasion. The main component of khat is cathinone, which is structurally and functionally similar to amphetamine and cocaine. Several studies have demonstrated that khat chewing has unfavorable cardiovascular effects. The effect on the myocardium could be explained by its effect on the heart rate, blood pressure, its vasomotor effect on the coronary vessels, and its amphetamine–like effects. However, its direct effect on the myocardium needs further elaboration. To date, there are few articles that contribute death among khat chewers to khat-induced heart failure. Further studies are needed to address the risk factors in khat chewers that may explain khat-induced cardiotoxicity, cardiomyopathy, and heart failure. PMID:25960830

  13. Uncertainties in container failure time predictions

    SciTech Connect

    Williford, R.E.

    1990-01-01

    Stochastic variations in the local chemical environment of a geologic waste repository can cause corresponding variations in container corrosion rates and failure times, and thus in radionuclide release rates. This paper addresses how well the future variations in repository chemistries must be known in order to predict container failure times that are bounded by a finite time period within the repository lifetime. Preliminary results indicate that a 5000 year scatter in predicted container failure times requires that repository chemistries be known to within {plus minus}10% over the repository lifetime. These are small uncertainties compared to current estimates. 9 refs., 3 figs.

  14. Extracorporeal Life Support for Pediatric Heart Failure

    PubMed Central

    Burke, Christopher R.; McMullan, D. Michael

    2016-01-01

    Extracorporeal life support (ECLS) represents an essential component in the treatment of the pediatric patient with refractory heart failure. Defined as the use of an extracorporeal system to provide cardiopulmonary support, ECLS provides hemodynamic support to facilitate end-organ recovery and can be used as a salvage therapy during acute cardiorespiratory failure. Support strategies employed in pediatric cardiac patients include bridge to recovery, bridge to therapy, and bridge to transplant. Advances in extracorporeal technology and refinements in patient selection have allowed wider application of this therapy in pediatric heart failure patients. PMID:27812522

  15. Right heart failure: toward a common language.

    PubMed

    Mehra, Mandeep R; Park, Myung H; Landzberg, Michael J; Lala, Anuradha; Waxman, Aaron B

    2014-02-01

    In this perspective, the International Right Heart Foundation Working Group moves a step forward to develop a common language to describe the development and defects that exemplify the common syndrome of right heart failure. We first propose fundamental definitions of the distinctive components of the right heart circulation and provide consensus on a universal definition of right heart failure. These definitions will form the foundation for describing a uniform nomenclature for right heart circulatory failure with a view to foster collaborative research initiatives and conjoint education in an effort to provide insight into echanisms of disease unique to the right heart.

  16. Right heart failure: toward a common language

    PubMed Central

    2013-01-01

    Abstract In this guideline, the International Right Heart Foundation Working Group moves a step forward to develop a common language to describe the development and defects that exemplify the common syndrome of right heart failure. We first propose fundamental definitions of the distinctive components of the right heart circulation and provide consensus on a universal definition of right heart failure. These definitions will form the foundation for describing a uniform nomenclature for right heart circulatory failure with a view to foster collaborative research initiatives and conjoint education in an effort to provide insight into mechanisms of disease unique to the right heart. PMID:25006413

  17. Right heart failure: toward a common language.

    PubMed

    Mehra, Mandeep R; Park, Myung H; Landzberg, Michael J; Lala, Anuradha; Waxman, Aaron B

    2013-12-01

    In this guideline, the International Right Heart Foundation Working Group moves a step forward to develop a common language to describe the development and defects that exemplify the common syndrome of right heart failure. We first propose fundamental definitions of the distinctive components of the right heart circulation and provide consensus on a universal definition of right heart failure. These definitions will form the foundation for describing a uniform nomenclature for right heart circulatory failure with a view to foster collaborative research initiatives and conjoint education in an effort to provide insight into mechanisms of disease unique to the right heart. PMID:25006413

  18. Right heart failure: toward a common language.

    PubMed

    Mehra, Mandeep R; Park, Myung H; Landzberg, Michael J; Lala, Anuradha; Waxman, Aaron B

    2014-02-01

    In this perspective, the International Right Heart Foundation Working Group moves a step forward to develop a common language to describe the development and defects that exemplify the common syndrome of right heart failure. We first propose fundamental definitions of the distinctive components of the right heart circulation and provide consensus on a universal definition of right heart failure. These definitions will form the foundation for describing a uniform nomenclature for right heart circulatory failure with a view to foster collaborative research initiatives and conjoint education in an effort to provide insight into echanisms of disease unique to the right heart. PMID:24268184

  19. Relationship between obesity and early failure of total knee prostheses

    PubMed Central

    Bordini, Barbara; Stea, Susanna; Cremonini, Sara; Viceconti, Marco; De Palma, Rossana; Toni, Aldo

    2009-01-01

    Background Obesity is a risk factor for knee arthritis. Total knee arthroplasty is the definitive surgical treatment of this disease. Therefore, a high percentage of subjects treated are overweight. Since 2000 in the Emilia-Romagna Region the Register of Orthopedic Prosthetic Implantology, RIPO, has recorded data of all the primary and revision operations performed on the knee; height and weight of patients at the time of surgery have also been recorded. Methods To understand how overweight and obesity affect the outcome of knee arthroplasty, a population of subjects treated with cemented total knee arthroplasty between 2000 and 2005 was studied. 9735 knee prostheses were implanted in 8892 patients; 18.9% of the patients were normal weight, 48.2% were overweight (25 < Body Mass Index <= 30), 31.1% were obese (30 < BMI <= 40), and 1.8% were morbidly obese (BMI > 40). Mean and range of follow-up were respectively 3.1 and 1.5–6 yrs. Implant failure was defined as the exchange of at least one component for whatever reason. Results In normal weight patients there were 36 failures out of 1840 implants (1.96%), in overweight patients there were 87 out of 4692 (1.85%), in obese 59 out of 3031 (1.94%), and in morbidly obese there were 4 out of 172 (2.3%). The mean time to failure for each class was 1.57, 1.48, 1.60, 1.77 yrs. Cox regression analyses showed that the risk of implant failure was not influenced by BMI, absolute body weight, or sex. Conversely, an increased failure risk was observed in mobile meniscus prostheses in comparison with those with a fixed meniscus (Rate Ratio 1.88); an increased failure risk was also related to age (Rate Ratio 1.05 per year). These results were also confirmed when considering septic loosening as the end-point. There were no differences in the rate of perioperative complications and death in the 4 classes of BMI. Conclusion In conclusion, cemented knee prostheses, implanted in patients with arthritis do not have significantly

  20. Diastolic Function in Heart Failure

    PubMed Central

    Kovács, Sándor J

    2015-01-01

    Heart failure has reached epidemic proportions, and diastolic heart failure or heart failure with preserved ejection fraction (HFpEF) constitutes about 50% of all heart failure admissions. Long-term prognosis of both reduced ejection fraction heart failure and HFpEF are similarly dismal. No pharmacologic agent has been developed that actually treats or repairs the physiologic deficit(s) responsible for HFpEF. Because the physiology of diastole is both subtle and counterintuitive, its role in heart failure has received insufficient attention. In this review, the focus is on the physiology of diastole in heart failure, the dominant physiologic laws that govern the process in all hearts, how all hearts work as a suction pump, and, therefore, the elucidation and characterization of what actually is meant by “diastolic function”. The intent is for the reader to understand what diastolic function actually is, what it is not, and how to measure it. Proper measurement of diastolic function requires one to go beyond the usual E/A, E/E′, etc. phenomenological metrics and employ more rigorous causality (mathematical modeling) based parameters of diastolic function. The method simultaneously provides new physiologic insight into the meaning of in vivo “equilibrium volume” of the left ventricle (LV), longitudinal versus transverse volume accommodation of the chamber, diastatic “ringing” of the mitral annulus, and the mechanism of L-wave generation, as well as availability of a load-independent index of diastolic function (LIIDF). One important consequence of understanding what diastolic function is, is the recognition that all that current therapies can do is basically alter the load, rather than actually “repair” the functional components (chamber stiffness, chamber relaxation). If beneficial (biological/structural/metabolic) remodeling due to therapy does manifest ultimately as improved diastolic function, it is due to resumption of normal physiology (as in

  1. Renal failure in fulminant hepatic failure and terminal cirrhosis: a comparison between incidence, types, and prognosis.

    PubMed Central

    Ring-Larsen, H; Palazzo, U

    1981-01-01

    Forty patients with terminal cirrhosis and 40 patients with fulminant hepatic failure-all consecutively admitted-were studied with regard to incidence, types, and prognosis of complicating renal insufficiency. Renal failure was considered present when the serum creatinine was greater than 0.20 mmol/l. Of the patients with cirrhosis 26 (65%) developed renal failure. In 15 the type was functional, in three due to acute tubular necrosis, and in eight indeterminable. Of the patients with fulminant hepatic failure 22 (55%) had renal insufficiency; of these 13 had functional renal failure, five acute tubular necrosis, and in four the type was indeterminable. In both categories of patients, renal failure was equally frequent among patients with or without gastrointestinal bleeding and with or without ascites or diuretic therapy. The biochemical tests of liver function were similar in patients with or without renal failure in both categories. The mean renal blood flow in seven unselected patients with fulminant hepatic failure was reduced in the same order as previously observed in patients with cirrhosis. In terminal cirrhosis the mortality rate was 88% in the presence of renal failure, 71% in its absence (p greater than 0.05), while the same figures in fulminant hepatic failure were 100% and 67% (p less than 0.05). The incidence, relative frequency, and prognosis of renal failure were not different in the two conditions, indicating identical pathophysiological circumstances. PMID:7262632

  2. Failure Mode Identification Through Clustering Analysis

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    Research has shown that nearly 80% of the costs and problems are created in product development and that cost and quality are essentially designed into products in the conceptual stage. Currently, failure identification procedures (such as FMEA (Failure Modes and Effects Analysis), FMECA (Failure Modes, Effects and Criticality Analysis) and FTA (Fault Tree Analysis)) and design of experiments are being used for quality control and for the detection of potential failure modes during the detail design stage or post-product launch. Though all of these methods have their own advantages, they do not give information as to what are the predominant failures that a designer should focus on while designing a product. This work uses a functional approach to identify failure modes, which hypothesizes that similarities exist between different failure modes based on the functionality of the product/component. In this paper, a statistical clustering procedure is proposed to retrieve information on the set of predominant failures that a function experiences. The various stages of the methodology are illustrated using a hypothetical design example.

  3. Failure Analysis and Quality Control of Microwave Devices

    NASA Astrophysics Data System (ADS)

    Ming, Zhimao; Zong, Bo; Bai, Xiaoshu

    2016-02-01

    Microwave devices have been widely used in the communication and navigation and navigation fields. The reliability level of microwave devices is an important factor to affect the reliability of electronic equipment. The statistical analysis for the failure of sixty microwave devices was presented and the main causes of failure were given. The failure is mainly analyzed from three aspects below, the surface failure mechanism, the interior failure mechanism and the failure mechanism of electrode system and encapsulation. The surface failure mechanism is analyzed from four aspects, ionic contamination on the surface, silicon dioxide layer defect, the influence of interface states between silicon and silicon dioxide, radiation ionization trap. The interior failure mechanism is analyzed from two aspects, failure caused by thermal breakdown and failure due to latch-up effect of integrated circuit. The failure mechanism of electrode system and encapsulation is analyzed from two aspects, failure mechanism of metallization system and failure mechanism of metallization system of bonding. Meanwhile, the results showed that operation, process, adjustment, components and using problems were the main causes of failure. The valuable statistical data and analysis results were provided for the quality control of microwave devices.

  4. Outpatient treatment of heart failure.

    PubMed

    McConaghy, John R; Smith, Steven R

    2002-06-01

    Heart failure (HF) affects more than 2 million adults in the United States. This common, costly, and disabling disorder mainly affects the elderly, with prevalence rates up to 10% in patients older than 65 years. The management of HF is responsible for millions of outpatient visits per year, is the most common discharge diagnosis for Medicare beneficiaries, and accounts for more than 5% of total health care dollars spent.

  5. Virtually-synchronous communication based on a weak failure suspector

    NASA Technical Reports Server (NTRS)

    Schiper, Andre; Ricciardi, Aleta

    1993-01-01

    Failure detectors (or, more accurately Failure Suspectors (FS)) appear to be a fundamental service upon which to build fault-tolerant, distributed applications. This paper shows that a FS with very weak semantics (i.e., that delivers failure and recovery information in no specific order) suffices to implement virtually-synchronous communication (VSC) in an asynchronous system subject to process crash failures and network partitions. The VSC paradigm is particularly useful in asynchronous systems and greatly simplifies building fault-tolerant applications that mask failures by replicating processes. We suggest a three-component architecture to implement virtually-synchronous communication: (1) at the lowest level, the FS component; (2) on top of it, a component (2a) that defines new views; and (3) a component (2b) that reliably multicasts messages within a view. The issues covered in this paper also lead to a better understanding of the various membership service semantics proposed in recent literature.

  6. Real-time monitoring of progression towards renal failure in primary care patients.

    PubMed

    Diggle, Peter J; Sousa, Inês; Asar, Özgür

    2015-07-01

    Chronic renal failure is a progressive condition that, typically, is asymptomatic for many years. Early detection of incipient kidney failure enables ameliorative treatment that can slow the rate of progression to end-stage renal failure, at which point expensive and invasive renal replacement therapy (dialysis or transplantation) is required. We use routinely collected clinical data from a large sample of primary care patients to develop a system for real-time monitoring of the progression of undiagnosed incipient renal failure. Progression is characterized as the rate of change in a person's kidney function as measured by the estimated glomerular filtration rate, an adjusted version of serum creatinine level in a blood sample. Clinical guidelines in the UK suggest that a person who is losing kidney function at a relative rate of at least 5% per year should be referred to specialist secondary care. We model the time-course of a person's underlying kidney function through a combination of explanatory variables, a random intercept and a continuous-time, non-stationary stochastic process. We then use the model to calculate for each person the predictive probability that they meet the clinical guideline for referral to secondary care. We suggest that probabilistic predictive inference linked to clinical criteria can be a useful component of a real-time surveillance system to guide, but not dictate, clinical decision-making.

  7. Taper junction failure in large-diameter metal-on-metal bearings

    PubMed Central

    Langton, D. J.; Sidaginamale, R.; Lord, J. K.; Nargol, A. V. F.; Joyce, T. J.

    2012-01-01

    Objectives An ongoing prospective study to investigate failing metal-on-metal hip prostheses was commenced at our centre in 2008. We report on the results of the analysis of the first consecutive 126 failed mated total hip prostheses from a single manufacturer. Methods Analysis was carried out using highly accurate coordinate measuring to calculate volumetric and linear rates of the articular bearing surfaces and also the surfaces of the taper junctions. The relationship between taper wear rates and a number of variables, including bearing diameter and orientation of the acetabular component, was investigated. Results The measured rates of wear and distribution of material loss from the taper surfaces appeared to show that the primary factor leading to taper failure is the increased lever arm acting on this junction in contemporary large-diameter metal-on-metal hip replacements. Conclusions Our analysis suggests that varus stems, laterally engaging taper systems and larger head diameters all contribute to taper failure. PMID:23610672

  8. Duralumin - Defects and Failures

    NASA Technical Reports Server (NTRS)

    Nelson, WM

    1927-01-01

    It is proposed in this paper to identify some of the defects and failures in duralumin most frequently encountered by the aircraft industry with a view to indicate their importance. The defects and failures in duralumin may be classified into the following groups: 1) defects produced during manufacture; 2) defects produced during fabrication; 3) corrosion and erosion; and 4) fatigue failures. Only the first two will be covered in this report.

  9. Brain components

    MedlinePlus

    ... 3 major components of the brain are the cerebrum, cerebellum, and brain stem. The cerebrum is divided into left and right hemispheres, each ... gray matter) is the outside portion of the cerebrum and provides us with functions associated with conscious ...

  10. Examination of cadmium safety rod thermal test specimens and failure mechanism evaluation

    SciTech Connect

    Thomas, J.K.; Peacock, H.B.; Iyer, N.C.

    1992-01-01

    The reactor safety rods may be subjected to high temperatures due to gamma heating after the core coolant level has dropped during the ECS phase of a hypothetical LOCA event. Accordingly, an experimental cadmium safety rod testing subtask was established as part of a task to address the response of reactor core components to this accident. Companion reports describe the experiments and a structural evaluation (finite element analysis) of the safety rod. This report deals primarily with the examination of the test specimens, evaluation of possible failure mechanisms, and confirmatory separate effects experiments. It is concluded that the failures observed in the cadmium safety rod thermal tests which occurred at low temperature (T < 600{degrees}C) with slow thermal ramp rates (slow cladding strain rates) resulted from localized dissolution of the stainless steel cladding by the cadmium/aluminum solution and subsequent ductility exhaustion and rupture. The slow thermal ramp rate is believed to be the root cause for the failures; specifically, the slow ramp rate led to localized cladding shear deformation which ruptured the protective oxide film on the cladding inner surface and allowed dissolution to initiate. The test results and proposed failure mechanism support the conclusion that the rods would not fail below 500{degrees}C even at slow ramp rates. The safety rod thermal test specimen failures which occurred at high temperature (T > 800{degrees}C) with fast thermal ramp rates are concluded to be mechanical in nature without significant environmental degradation. Based on these tests, tasks were initiated to design and manufacture B{sub 4}C safety rods to replace the cadmium safety rods. The B{sub 4}C safety rods have been manufactured at this time and it is currently planned to charge them to the reactor in the near future. 60 refs.

  11. Destructive Single-Event Failures in Diodes

    NASA Technical Reports Server (NTRS)

    Casey, Megan C.; Gigliuto, Robert A.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Kim, Hak; Chen, Dakai; Phan, Anthony M.; LaBel, Kenneth A.

    2013-01-01

    In this summary, we have shown that diodes are susceptible to destructive single-event effects, and that these failures occur along the guard ring. By determining the last passing voltages, a safe operating area can be derived. By derating off of those values, rather than by the rated voltage, like what is currently done with power MOSFETs, we can work to ensure the safety of future missions. However, there are still open questions about these failures. Are they limited to a single manufacturer, a small number, or all of them? Is there a threshold rated voltage that must be exceeded to see these failures? With future work, we hope to answer these questions. In the full paper, laser results will also be presented to verify that failures only occur along the guard ring.

  12. Telerehabilitation for patients with heart failure.

    PubMed

    Tousignant, Michel; Mampuya, Warner Mbuila

    2015-02-01

    Heart failure is a chronic and progressive condition that is associated with high morbidity and mortality rates. Even though cardiac rehabilitation (CR) has been shown to be beneficial to heart failure patients, only a very small proportion of them will actually be referred and eventually participate. The low participation rate is due in part to accessibility and travel difficulties. Telerehabilitation is a new approach in the rehabilitation field that allows patients to receive a complete rehabilitation program at home in a safe manner and under adequate supervision. We believe that by increasing accessibility to CR, telerehabilitation programs will significantly improve heart failure patients' functional capacity and quality of life. However, it is crucial to provide policy makers with evidence-based data on cardiac telerehabilitation if we want to see its successful implementation in heart failure patients.

  13. Model for heart failure education.

    PubMed

    Baldonado, Analiza; Dutra, Danette; Abriam-Yago, Katherine

    2014-01-01

    Heart failure (HF) is the heart's inability to meet the body's need for blood and oxygen. According to the American Heart Association 2013 update, approximately 5.1 million people are diagnosed with HF in the United States in 2006. Heart failure is the most common diagnosis for hospitalization. In the United States, the HF direct and indirect costs are estimated to be US $39.2 billion in 2010. To address this issue, nursing educators designed innovative teaching frameworks on HF management both in academia and in clinical settings. The model was based on 2 resources: the American Association of Heart Failure Nurses (2012) national nursing certification and the award-winning Pierce County Responsive Care Coordination Program. The HF educational program is divided into 4 modules. The initial modules offer foundational levels of Bloom's Taxonomy then progress to incorporate higher-levels of learning when modules 3 and 4 are reached. The applicability of the key components within each module allows formatting to enhance learning in all areas of nursing, from the emergency department to intensive care units to the medical-surgical step-down units. Also applicable would be to provide specific aspects of the modules to nurses who care for HF patients in skilled nursing facility, rehabilitation centers, and in the home-health care setting. PMID:25140745

  14. Ampoule Failure System

    NASA Technical Reports Server (NTRS)

    Watring, Dale A. (Inventor); Johnson, Martin L. (Inventor)

    1996-01-01

    An ampoule failure system for use in material processing furnaces comprising a containment cartridge and an ampoule failure sensor. The containment cartridge contains an ampoule of toxic material therein and is positioned within a furnace for processing. An ampoule failure probe is positioned in the containment cartridge adjacent the ampoule for detecting a potential harmful release of toxic material therefrom during processing. The failure probe is spaced a predetermined distance from the ampoule and is chemically chosen so as to undergo a timely chemical reaction with the toxic material upon the harmful release thereof. The ampoule failure system further comprises a data acquisition system which is positioned externally of the furnace and is electrically connected to the ampoule failure probe so as to form a communicating electrical circuit. The data acquisition system includes an automatic shutdown device for shutting down the furnace upon the harmful release of toxic material. It also includes a resistance measuring device for measuring the resistance of the failure probe during processing. The chemical reaction causes a step increase in resistance of the failure probe whereupon the automatic shutdown device will responsively shut down the furnace.

  15. Immune mediated liver failure

    PubMed Central

    Wang, Xiaojing; Ning, Qin

    2014-01-01

    Liver failure is a clinical syndrome of various etiologies, manifesting as jaundice, encephalopathy, coagulopathy and circulatory dysfunction, which result in subsequent multiorgan failure. Clinically, liver failure is classified into four categories: acute, subacute, acute-on-chronic and chronic liver failure. Massive hepatocyte death is considered to be the core event in the development of liver failure, which occurs when the extent of hepatocyte death is beyond the liver regenerative capacity. Direct damage and immune-mediated liver injury are two major factors involved in this process. Increasing evidence has suggested the essential role of immune-mediated liver injury in the pathogenesis of liver failure. Here, we review the evolved concepts concerning the mechanisms of immune-mediated liver injury in liver failure from human and animal studies. Both innate and adaptive immunity, especially the interaction of various immune cells and molecules as well as death receptor signaling system are discussed. In addition, we highlight the concept of “immune coagulation”, which has been shown to be related to the disease progression and liver injury exacerbation in HBV related acute-on-chronic liver failure. PMID:26417328

  16. Physicists and failure

    NASA Astrophysics Data System (ADS)

    Raheem, Ruby; zilch, Mortimer

    2015-08-01

    In reply to a post on the physicsworld.com blog about the central role of failure in physics (“Success, failure and women in physics”, 10 June, http://ow.ly/O8kvR; see also “Failing better,” Editorial, July p15).

  17. Modelling of failure of structural textile composites

    NASA Astrophysics Data System (ADS)

    Svensson, N.; Gilchrist, M. D.

    This paper summarizes extensive experimental work regarding the manufacture, mechanical characterization and modelling of textile thermoplastic composites produced by means of commingled yarns. These composites are believed to have a high potential for applications in structural automotive components. However, methods need to be developed for faster manufacturing and reliable prediction of the component mechanical performance and failure. A practical approach of finite element modelling of the stiffness and strength behaviour of these composites is briefly discussed.

  18. System diagnostics using qualitative analysis and component functional classification

    DOEpatents

    Reifman, Jaques; Wei, Thomas Y. C.

    1993-01-01

    A method for detecting and identifying faulty component candidates during off-normal operations of nuclear power plants involves the qualitative analysis of macroscopic imbalances in the conservation equations of mass, energy and momentum in thermal-hydraulic control volumes associated with one or more plant components and the functional classification of components. The qualitative analysis of mass and energy is performed through the associated equations of state, while imbalances in momentum are obtained by tracking mass flow rates which are incorporated into a first knowledge base. The plant components are functionally classified, according to their type, as sources or sinks of mass, energy and momentum, depending upon which of the three balance equations is most strongly affected by a faulty component which is incorporated into a second knowledge base. Information describing the connections among the components of the system forms a third knowledge base. The method is particularly adapted for use in a diagnostic expert system to detect and identify faulty component candidates in the presence of component failures and is not limited to use in a nuclear power plant, but may be used with virtually any type of thermal-hydraulic operating system.

  19. System diagnostics using qualitative analysis and component functional classification

    DOEpatents

    Reifman, J.; Wei, T.Y.C.

    1993-11-23

    A method for detecting and identifying faulty component candidates during off-normal operations of nuclear power plants involves the qualitative analysis of macroscopic imbalances in the conservation equations of mass, energy and momentum in thermal-hydraulic control volumes associated with one or more plant components and the functional classification of components. The qualitative analysis of mass and energy is performed through the associated equations of state, while imbalances in momentum are obtained by tracking mass flow rates which are incorporated into a first knowledge base. The plant components are functionally classified, according to their type, as sources or sinks of mass, energy and momentum, depending upon which of the three balance equations is most strongly affected by a faulty component which is incorporated into a second knowledge base. Information describing the connections among the components of the system forms a third knowledge base. The method is particularly adapted for use in a diagnostic expert system to detect and identify faulty component candidates in the presence of component failures and is not limited to use in a nuclear power plant, but may be used with virtually any type of thermal-hydraulic operating system. 5 figures.

  20. Serum vitamin B12 in renal failure

    PubMed Central

    Matthews, D. M.; Beckett, A. Gordon; Maxwell, Patricia

    1962-01-01

    The serum vitamin B12 level was abnormally high in 14 out of 32 cases of renal failure. This was probably due to impaired excretion of the vitamin, but the results of measurements of the rate of excretion of radioactive vitamin B12 did not provide unequivocal evidence on this point; other possible explanations are discussed. Renal failure must be added to the causes of high serum B12 levels. PMID:13933867

  1. Acute Decompensated Heart Failure

    PubMed Central

    Joseph, Susan M.; Cedars, Ari M.; Ewald, Gregory A.; Geltman, Edward M.; Mann, Douglas L.

    2009-01-01

    Hospitalizations for acute decompensated heart failure are increasing in the United States. Moreover, the prevalence of heart failure is increasing consequent to an increased number of older individuals, as well as to improvement in therapies for coronary artery disease and sudden cardiac death that have enabled patients to live longer with cardiovascular disease. The main treatment goals in the hospitalized patient with heart failure are to restore euvolemia and to minimize adverse events. Common in-hospital treatments include intravenous diuretics, vasodilators, and inotropic agents. Novel pharmaceutical agents have shown promise in the treatment of acute decompensated heart failure and may simplify the treatment and reduce the morbidity associated with the disease. This review summarizes the contemporary management of patients with acute decompensated heart failure. PMID:20069075

  2. Common-Cause Failure Analysis in Event Assessment

    SciTech Connect

    Dana L. Kelly; Dale M. Rasmuson

    2008-09-01

    This paper describes the approach taken by the U. S. Nuclear Regulatory Commission to the treatment of common-cause failure in probabilistic risk assessment of operational events. The approach is based upon the Basic Parameter Model for common-cause failure, and examples are illustrated using the alpha-factor parameterization, the approach adopted by the NRC in their Standardized Plant Analysis Risk (SPAR) models. The cases of a failed component (with and without shared common-cause failure potential) and a component being unavailable due to preventive maintenance or testing are addressed. The treatment of two related failure modes (e.g., failure to start and failure to run) is a new feature of this paper. These methods are being applied by the NRC in assessing the risk significance of operational events for the Significance Determination Process (SDP) and the Accident Sequence Precursor (ASP) program.

  3. Failure Analysis of Electrical Pin Connectors

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Baughman, James M.; Smith, Stephen W.; Herath, Jeffrey A.

    2008-01-01

    A study was initiated to determine the root cause of failure for circuit board electrical connection pins that failed during vibRatory testing. The circuit board is part of an unmanned space probe, and the vibratory testing was performed to ensure component survival of launch loading conditions. The results of this study show that the pins failed as a result of fatigue loading.

  4. Multiaxial failure characterization of composites

    SciTech Connect

    Groves, S.E.; Sanchez, R.J.; Feng, W.W.

    1991-02-01

    The primary objective of this research has been to develop a multiaxial testing capability for continuous fiber composites using the axial/torsion/internal pressurization of tubes. This capability enables one to generate the two-dimensional (in-plane) failure surface for these materials. The multiaxial test specimen consists of a 5.08 cm (2.0 in.) diameter composite tube with 15{degrees} cast epoxy end cones for gripping. The unique advancement with this new technique is the simple, but very efficient, gripping mechanism that provides a very smooth transition in load from the grip into the specimen. This has eliminated grip related stress risers in the composite tube. Consequently, most of the failures occur in the gage section of the tube. This system is coupled into a biaxial MTS servo hydraulic test machine capable of simultaneously applying axial load, torque, and internal pressure, providing one complete control of the axial, transverse, and shear stresses that develop in the wall of the composite tube. This paper will present the failure results obtained to date for various laminate configurations of Toray 1000/DER332-T403 filament wound carbon/epoxy tubes along with T300/F263 prepreg carbon/epoxy tubes. The goal of our efforts is to develop a more fully characterized three-dimensional failure criterion for these materials. This model will then be incorporated into a large three-dimensional orthotropic finite element model for structural analysis as well as a specialized three-dimensional orthotropic finite element model capable of detailed sub-ply level analysis on sub-structural components. 19 refs., 10 figs.

  5. Accountability for network backup failures

    SciTech Connect

    Benson, W.H.

    1994-02-01

    Regular hard disk backups for workstations are widely recommended. The necessity of backups -- akin to one`s own mortality -- is something most people would rather not think about. This attitude has two consequences. When people do subscribe to automated network backups, they expect the system to perform at a high level of reliability and that their files will be there for them when they need them. Second, they usually fail to appreciate that reliability is a shared responsibility. Although ostensibly their only responsibility is to keep the computer powered on overnight, there are actually many more opportunities for failure within the user`s jurisdiction than in other parts of the infrastructure. High reliability is almost a sine qua non for backups. We describe a strategy for enhancing reliability based on the principle of accountability. This strategy involves monitoring the system, gathering statistics, detecting problems, anticipating problems, troubleshooting, and finally determining where failure occurred within the infrastructure and who should be accountable. We describe a specific backup system in a specific network environment to illustrate the value of accountability. This system, macdumps, backs up Macintosh disks over an AppleTalk network. The original software was written by Dan Tappan of BBN in the early years of the Mac and is available by ftp for noncommercial use. It has proven reliable and robust. Despite the high quality of the fundamental software, there are still many opportunities for failure within the infrastructure. We first discuss accountability in the context of network backups, then briefly describe how the backup system operates, the components of the infrastructure, types of failures experienced, and then summarize our experience.

  6. Real-time forecasting and predictability of catastrophic failure events: from rock failure to volcanoes and earthquakes

    NASA Astrophysics Data System (ADS)

    Main, I. G.; Bell, A. F.; Naylor, M.; Atkinson, M.; Filguera, R.; Meredith, P. G.; Brantut, N.

    2012-12-01

    Accurate prediction of catastrophic brittle failure in rocks and in the Earth presents a significant challenge on theoretical and practical grounds. The governing equations are not known precisely, but are known to produce highly non-linear behavior similar to those of near-critical dynamical systems, with a large and irreducible stochastic component due to material heterogeneity. In a laboratory setting mechanical, hydraulic and rock physical properties are known to change in systematic ways prior to catastrophic failure, often with significant non-Gaussian fluctuations about the mean signal at a given time, for example in the rate of remotely-sensed acoustic emissions. The effectiveness of such signals in real-time forecasting has never been tested before in a controlled laboratory setting, and previous work has often been qualitative in nature, and subject to retrospective selection bias, though it has often been invoked as a basis in forecasting natural hazard events such as volcanoes and earthquakes. Here we describe a collaborative experiment in real-time data assimilation to explore the limits of predictability of rock failure in a best-case scenario. Data are streamed from a remote rock deformation laboratory to a user-friendly portal, where several proposed physical/stochastic models can be analysed in parallel in real time, using a variety of statistical fitting techniques, including least squares regression, maximum likelihood fitting, Markov-chain Monte-Carlo and Bayesian analysis. The results are posted and regularly updated on the web site prior to catastrophic failure, to ensure a true and and verifiable prospective test of forecasting power. Preliminary tests on synthetic data with known non-Gaussian statistics shows how forecasting power is likely to evolve in the live experiments. In general the predicted failure time does converge on the real failure time, illustrating the bias associated with the 'benefit of hindsight' in retrospective analyses

  7. PetH is rate-controlling in the interaction between PetH, a component of the supramolecular complex with photosystem II, and PetF, a light-dependent electron transfer protein

    SciTech Connect

    Okada, Ken

    2009-11-13

    Cyanobacterial PetH is similar to ferredoxin-NADP{sup +} oxidoreductase (FNR) of higher plants and comprises 2 components, CpcD-like rod linker and FNR proteins. Here, I show that PetH controls the rate of the interaction with PetF (ferredoxin [Fd1]). Purified recombinant PetH protein, which cut off a CpcD-like rod linker domain, and Fd1 were used in detailed surface plasmon resonance analyses. The interaction between FNR and Fd1 chiefly involved extremely fast binding and dissociation reactions and the FNR affinity for Fd1 was stronger than the Fd1 affinity for FNR. The dissociation constant values were determined as approximately 93.65 {mu}M (FNR) for Fd1 and 1.469 mM (Fd1) for FNR.

  8. Damage mechanics - failure modes

    SciTech Connect

    Krajcinovic, D.; Vujosevic, M.

    1996-12-31

    The present study summarizes the results of the DOE sponsored research program focused on the brittle failure of solids with disordered microstructure. The failure is related to the stochastic processes on the microstructural scale; namely, the nucleation and growth of microcracks. The intrinsic failure modes, such as the percolation, localization and creep rupture, are studied by emphasizing the effect of the micro-structural disorder. A rich spectrum of physical phenomena and new concepts that emerges from this research demonstrates the reasons behind the limitations of traditional, deterministic, and local continuum models.

  9. Failure of Viral Shells

    NASA Astrophysics Data System (ADS)

    Klug, William S.; Bruinsma, Robijn F.; Michel, Jean-Philippe; Knobler, Charles M.; Ivanovska, Irena L.; Schmidt, Christoph F.; Wuite, Gijs J. L.

    2006-12-01

    We report a combined theoretical and experimental study of the structural failure of viral shells under mechanical stress. We find that discontinuities in the force-indentation curve associated with failure should appear when the so-called Föppl von Kármán (FvK) number exceeds a critical value. A nanoindentation study of a viral shell subject to a soft-mode instability, where the stiffness of the shell decreases with increasing pH, confirms the predicted onset of failure as a function of the FvK number.

  10. Root Causes of Component Failures Program: Methods and applications

    SciTech Connect

    Satterwhite, D G; Cadwallader, L C; Vesely, W E; Meale, B M

    1986-12-01

    This report contains information pertaining to definitions, methodologies, and applications of root cause analysis. Of specific interest, and highlighted throughout the discussion, are applications pertaining to current and future Nuclear Regulatory Commission (NRC) light water reactor safety programs. These applications are discussed in view of addressing specific program issues under NRC consideration and reflect current root cause analysis capabilities.

  11. Study of intermittent field hardware failure data in digital electronics

    NASA Technical Reports Server (NTRS)

    Oneill, E. J.; Halverson, J. R.

    1980-01-01

    The collection and analysis of data concerning intermittent dailures in digital devices was performed using data from a computer design for shipboard usage. The failure data consisted of actual field failures classified by failure mechanisms and their likelihood of having been intermittent, potentially intermittent, or hard. Each class was studies with respect to computer operation in the ranges of 0 to 2,000 hours, 0 to 5, hours, and 0 to 10,000 hours. The study was done at the computer level as well as the microcircuit level. Results indicate that as age increases, the quasi-intermittent failure rate increases and the mean time to failure descreases.

  12. Hyperfrequency components

    NASA Astrophysics Data System (ADS)

    1994-09-01

    The document has a collection of 19 papers (11 on technologies, 8 on applications) by 26 authors and coauthors. Technological topics include: evolution from conventional HEMT's double heterojunction and planar types of pseudomorphic HEMT's; MMIC R&D and production aspects for very-low-noise, low-power, and very-low-noise, high-power applications; hyperfrequency CAD tools; parametric measurements of hyperfrequency components on plug-in cards for design and in-process testing uses; design of Class B power amplifiers and millimetric-wave, bigrid-transistor mixers, exemplifying combined use of three major types of physical simulation in electrical modeling of microwave components; FET's for power amplification at up to 110 GHz; production, characterization, and nonlinear applications of resonant tunnel diodes. Applications topics include: development of active modules for major European programs; tubes versus solid-state components in hyperfrequency applications; status and potentialities of national and international cooperative R&D on MMIC's and CAD of hyperfrequency circuitry; attainable performance levels in multifunction MMIC applications; state of the art relative of MESFET power amplifiers (Bands S, C, X, Ku); creating a hyperfrequency functions library, of parametrizable reference cells or macrocells; and design of a single-stage, low-noise, band-W amplifier toward development of a three-stage amplifier.

  13. Component separations.

    PubMed

    Heller, Lior; McNichols, Colton H; Ramirez, Oscar M

    2012-02-01

    Component separation is a technique used to provide adequate coverage for midline abdominal wall defects such as a large ventral hernia. This surgical technique is based on subcutaneous lateral dissection, fasciotomy lateral to the rectus abdominis muscle, and dissection on the plane between external and internal oblique muscles with medial advancement of the block that includes the rectus muscle and its fascia. This release allows for medial advancement of the fascia and closure of up to 20-cm wide defects in the midline area. Since its original description, components separation technique underwent multiple modifications with the ultimate goal to decrease the morbidity associated with the traditional procedure. The extensive subcutaneous lateral dissection had been associated with ischemia of the midline skin edges, wound dehiscence, infection, and seroma. Although the current trend is to proceed with minimally invasive component separation and to reinforce the fascia with mesh, the basic principles of the techniques as described by Ramirez et al in 1990 have not changed over the years. Surgeons who deal with the management of abdominal wall defects are highly encouraged to include this technique in their collection of treatment options.

  14. Hyperkalemia in Heart Failure.

    PubMed

    Sarwar, Chaudhry M S; Papadimitriou, Lampros; Pitt, Bertram; Piña, Ileana; Zannad, Faiez; Anker, Stefan D; Gheorghiade, Mihai; Butler, Javed

    2016-10-01

    Disorders of potassium homeostasis can potentiate the already elevated risk of arrhythmia in heart failure. Heart failure patients have a high prevalence of chronic kidney disease, which further heightens the risk of hyperkalemia, especially when renin-angiotensin-aldosterone system inhibitors are used. Acute treatment for hyperkalemia may not be tolerated in the long term. Recent data for patiromer and sodium zirconium cyclosilicate, used to treat and prevent high serum potassium levels on a more chronic basis, have sparked interest in the treatment of hyperkalemia, as well as the potential use of renin-angiotensin-aldosterone system inhibitors in patients who were previously unable to take these drugs or tolerated only low doses. This review discusses the epidemiology, pathophysiology, and outcomes of hyperkalemia in heart failure; provides an overview of traditional and novel ways to approach management of hyperkalemia; and discusses the need for further research to optimally treat heart failure.

  15. Hyperkalemia in Heart Failure.

    PubMed

    Sarwar, Chaudhry M S; Papadimitriou, Lampros; Pitt, Bertram; Piña, Ileana; Zannad, Faiez; Anker, Stefan D; Gheorghiade, Mihai; Butler, Javed

    2016-10-01

    Disorders of potassium homeostasis can potentiate the already elevated risk of arrhythmia in heart failure. Heart failure patients have a high prevalence of chronic kidney disease, which further heightens the risk of hyperkalemia, especially when renin-angiotensin-aldosterone system inhibitors are used. Acute treatment for hyperkalemia may not be tolerated in the long term. Recent data for patiromer and sodium zirconium cyclosilicate, used to treat and prevent high serum potassium levels on a more chronic basis, have sparked interest in the treatment of hyperkalemia, as well as the potential use of renin-angiotensin-aldosterone system inhibitors in patients who were previously unable to take these drugs or tolerated only low doses. This review discusses the epidemiology, pathophysiology, and outcomes of hyperkalemia in heart failure; provides an overview of traditional and novel ways to approach management of hyperkalemia; and discusses the need for further research to optimally treat heart failure. PMID:27687200

  16. What Causes Heart Failure?

    MedlinePlus

    ... the heart, leading to heart failure. High Blood Pressure Blood pressure is the force of blood pushing against the ... weaken your heart and lead to plaque buildup. Blood pressure is considered high if it stays at or ...

  17. Heart failure - tests

    MedlinePlus

    CHF - tests; Congestive heart failure - tests; Cardiomyopathy - tests; HF - tests ... An echocardiogram (Echo) is a test that uses sound waves to create a moving picture of the heart. The picture is much more detailed than a plain ...

  18. Types of Heart Failure

    MedlinePlus

    ... to be made. Here we delve into the importance of shared decision making. This content was last ... heart failure. Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Low Blood Pressure ...

  19. Classes of Heart Failure

    MedlinePlus

    ... to be made. Here we delve into the importance of shared decision making. HF Resources For Life ... heart failure. Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Low Blood Pressure ...

  20. Common Cause Failure Modeling

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Britton, Paul; Ring, Robert; Novack, Steven

    2015-01-01

    Space Launch System (SLS) Agenda: Objective; Key Definitions; Calculating Common Cause; Examples; Defense against Common Cause; Impact of varied Common Cause Failure (CCF) and abortability; Response Surface for various CCF Beta; Takeaways.

  1. Kidney (Renal) Failure

    MedlinePlus

    ... renal function using ureteral stenting, nephrostomy, surgery or dialysis. What is kidney (renal) failure? How is kidney ... as a urinary stent or kidney stone removal. Dialysis , including hemodialysis and peritoneal dialysis: These procedures remove ...

  2. What Causes Respiratory Failure?

    MedlinePlus

    ... easily move oxygen into your blood and remove carbon dioxide from your blood (gas exchange). This can cause a low oxygen level or high carbon dioxide level, or both, in your blood. Respiratory failure ...

  3. Prediction of Cascading Failures in Spatial Networks

    PubMed Central

    Shunkun, Yang; Dan, Lu

    2016-01-01

    Cascading overload failures are widely found in large-scale parallel systems and remain a major threat to system reliability; therefore, they are of great concern to maintainers and managers of different systems. Accurate cascading failure prediction can provide useful information to help control networks. However, for a large, gradually growing network with increasing complexity, it is often impractical to explore the behavior of a single node from the perspective of failure propagation. Fortunately, overload failures that propagate through a network exhibit certain spatial-temporal correlations, which allows the study of a group of nodes that share common spatial and temporal characteristics. Therefore, in this study, we seek to predict the failure rates of nodes in a given group using machine-learning methods. We simulated overload failure propagations in a weighted lattice network that start with a center attack and predicted the failure percentages of different groups of nodes that are separated by a given distance. The experimental results of a feedforward neural network (FNN), a recurrent neural network (RNN) and support vector regression (SVR) all show that these different models can accurately predict the similar behavior of nodes in a given group during cascading overload propagation. PMID:27093054

  4. Heterogeneity: The key to failure forecasting

    PubMed Central

    Vasseur, Jérémie; Wadsworth, Fabian B.; Lavallée, Yan; Bell, Andrew F.; Main, Ian G.; Dingwell, Donald B.

    2015-01-01

    Elastic waves are generated when brittle materials are subjected to increasing strain. Their number and energy increase non-linearly, ending in a system-sized catastrophic failure event. Accelerating rates of geophysical signals (e.g., seismicity and deformation) preceding large-scale dynamic failure can serve as proxies for damage accumulation in the Failure Forecast Method (FFM). Here we test the hypothesis that the style and mechanisms of deformation, and the accuracy of the FFM, are both tightly controlled by the degree of microstructural heterogeneity of the material under stress. We generate a suite of synthetic samples with variable heterogeneity, controlled by the gas volume fraction. We experimentally demonstrate that the accuracy of failure prediction increases drastically with the degree of material heterogeneity. These results have significant implications in a broad range of material-based disciplines for which failure forecasting is of central importance. In particular, the FFM has been used with only variable success to forecast failure scenarios both in the field (volcanic eruptions and landslides) and in the laboratory (rock and magma failure). Our results show that this variability may be explained, and the reliability and accuracy of forecast quantified significantly improved, by accounting for material heterogeneity as a first-order control on forecasting power. PMID:26307196

  5. Heterogeneity: The key to failure forecasting.

    PubMed

    Vasseur, Jérémie; Wadsworth, Fabian B; Lavallée, Yan; Bell, Andrew F; Main, Ian G; Dingwell, Donald B

    2015-08-26

    Elastic waves are generated when brittle materials are subjected to increasing strain. Their number and energy increase non-linearly, ending in a system-sized catastrophic failure event. Accelerating rates of geophysical signals (e.g., seismicity and deformation) preceding large-scale dynamic failure can serve as proxies for damage accumulation in the Failure Forecast Method (FFM). Here we test the hypothesis that the style and mechanisms of deformation, and the accuracy of the FFM, are both tightly controlled by the degree of microstructural heterogeneity of the material under stress. We generate a suite of synthetic samples with variable heterogeneity, controlled by the gas volume fraction. We experimentally demonstrate that the accuracy of failure prediction increases drastically with the degree of material heterogeneity. These results have significant implications in a broad range of material-based disciplines for which failure forecasting is of central importance. In particular, the FFM has been used with only variable success to forecast failure scenarios both in the field (volcanic eruptions and landslides) and in the laboratory (rock and magma failure). Our results show that this variability may be explained, and the reliability and accuracy of forecast quantified significantly improved, by accounting for material heterogeneity as a first-order control on forecasting power.

  6. Race and mortality after acute renal failure.

    PubMed

    Waikar, Sushrut S; Curhan, Gary C; Ayanian, John Z; Chertow, Glenn M

    2007-10-01

    Black patients receiving dialysis for end-stage renal disease in the United States have lower mortality rates than white patients. Whether racial differences exist in mortality after acute renal failure is not known. We studied acute renal failure in patients hospitalized between 2000 and 2003 using the Nationwide Inpatient Sample and found that black patients had an 18% (95% confidence interval [CI] 16 to 21%) lower odds of death than white patients after adjusting for age, sex, comorbidity, and the need for mechanical ventilation. Similarly, among those with acute renal failure requiring dialysis, black patients had a 16% (95% CI 10 to 22%) lower odds of death than white patients. In stratified analyses of patients with acute renal failure, black patients had significantly lower adjusted odds of death than white patients in settings of coronary artery bypass grafting, cardiac catheterization, acute myocardial infarction, congestive heart failure, pneumonia, sepsis, and gastrointestinal hemorrhage. Black patients were more likely than white patients to be treated in hospitals that care for a larger number of patients with acute renal failure, and black patients had lower in-hospital mortality than white patients in all four quartiles of hospital volume. In conclusion, in-hospital mortality is lower for black patients with acute renal failure than white patients. Future studies should assess the reasons for this difference. PMID:17855647

  7. Prediction of Cascading Failures in Spatial Networks.

    PubMed

    Shunkun, Yang; Jiaquan, Zhang; Dan, Lu

    2016-01-01

    Cascading overload failures are widely found in large-scale parallel systems and remain a major threat to system reliability; therefore, they are of great concern to maintainers and managers of different systems. Accurate cascading failure prediction can provide useful information to help control networks. However, for a large, gradually growing network with increasing complexity, it is often impractical to explore the behavior of a single node from the perspective of failure propagation. Fortunately, overload failures that propagate through a network exhibit certain spatial-temporal correlations, which allows the study of a group of nodes that share common spatial and temporal characteristics. Therefore, in this study, we seek to predict the failure rates of nodes in a given group using machine-learning methods. We simulated overload failure propagations in a weighted lattice network that start with a center attack and predicted the failure percentages of different groups of nodes that are separated by a given distance. The experimental results of a feedforward neural network (FNN), a recurrent neural network (RNN) and support vector regression (SVR) all show that these different models can accurately predict the similar behavior of nodes in a given group during cascading overload propagation.

  8. Heterogeneity: The key to failure forecasting.

    PubMed

    Vasseur, Jérémie; Wadsworth, Fabian B; Lavallée, Yan; Bell, Andrew F; Main, Ian G; Dingwell, Donald B

    2015-01-01

    Elastic waves are generated when brittle materials are subjected to increasing strain. Their number and energy increase non-linearly, ending in a system-sized catastrophic failure event. Accelerating rates of geophysical signals (e.g., seismicity and deformation) preceding large-scale dynamic failure can serve as proxies for damage accumulation in the Failure Forecast Method (FFM). Here we test the hypothesis that the style and mechanisms of deformation, and the accuracy of the FFM, are both tightly controlled by the degree of microstructural heterogeneity of the material under stress. We generate a suite of synthetic samples with variable heterogeneity, controlled by the gas volume fraction. We experimentally demonstrate that the accuracy of failure prediction increases drastically with the degree of material heterogeneity. These results have significant implications in a broad range of material-based disciplines for which failure forecasting is of central importance. In particular, the FFM has been used with only variable success to forecast failure scenarios both in the field (volcanic eruptions and landslides) and in the laboratory (rock and magma failure). Our results show that this variability may be explained, and the reliability and accuracy of forecast quantified significantly improved, by accounting for material heterogeneity as a first-order control on forecasting power. PMID:26307196

  9. Decomposition-Based Failure Mode Identification Method for Risk-Free Design of Large Systems

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    When designing products, it is crucial to assure failure and risk-free operation in the intended operating environment. Failures are typically studied and eliminated as much as possible during the early stages of design. The few failures that go undetected result in unacceptable damage and losses in high-risk applications where public safety is of concern. Published NASA and NTSB accident reports point to a variety of components identified as sources of failures in the reported cases. In previous work, data from these reports were processed and placed in matrix form for all the system components and failure modes encountered, and then manipulated using matrix methods to determine similarities between the different components and failure modes. In this paper, these matrices are represented in the form of a linear combination of failures modes, mathematically formed using Principal Components Analysis (PCA) decomposition. The PCA decomposition results in a low-dimensionality representation of all failure modes and components of interest, represented in a transformed coordinate system. Such a representation opens the way for efficient pattern analysis and prediction of failure modes with highest potential risks on the final product, rather than making decisions based on the large space of component and failure mode data. The mathematics of the proposed method are explained first using a simple example problem. The method is then applied to component failure data gathered from helicopter, accident reports to demonstrate its potential.

  10. Genesis Failure Investigation Report

    NASA Technical Reports Server (NTRS)

    Klein, John

    2004-01-01

    The-Genesis mission to collect solar-wind samples and return them to Earth for detailed analysis proceeded successfully for 3.5 years. During reentry on September 8, 2004, a failure in the entry, descent and landing sequence resulted in a crash landing of the Genesis sample return capsule. This document describes the findings of the avionics sub-team that supported the accident investigation of the JPL Failure Review Board.

  11. Socioeconomic Inequalities in Heart Failure.

    PubMed

    Díaz-Toro, Felipe; Verdejo, Hugo E; Castro, Pablo F

    2015-10-01

    Prevalence and incidence of chronic heart failure (CHF) has increased during the past decades. Beyond its impact on mortality rates, CHF severely impairs quality of life, particularly with the elderly and vulnerable population. Several studies have shown that CHF takes its toll mostly on the uneducated, low-income population, who exhibit impaired access to health care systems, less knowledge regarding its pathology and poorer self-care behaviors. This review summarizes the available evidence linking socioeconomic inequalities and CHF, focusing on the modifiable factors that may explain the impaired health outcomes in socioeconomically deprived populations. PMID:26462090

  12. Post-hepatectomy liver failure

    PubMed Central

    Kauffmann, Rondi

    2014-01-01

    Hepatectomies are among some of the most complex operative interventions performed. Mortality rates after major hepatectomy are as high as 30%, with post-hepatic liver failure (PHLF) representing the major source of morbidity and mortality. We present a review of PHLF, including the current definition, predictive factors, pre-operative risk assessment, techniques to prevent PHLF, identification and management. Despite great improvements in morbidity and mortality, liver surgery continues to demand excellent clinical judgement in selecting patients for surgery. Appropriate choice of pre-operative techniques to improve the functional liver remnant (FLR), fastidious surgical technique, and excellent post-operative management are essential to optimize patient outcomes. PMID:25392835

  13. Emerging Novel Therapies for Heart Failure

    PubMed Central

    Szema, Anthony M; Dang, Sophia; Li, Jonathan C

    2015-01-01

    Heart function fails when the organ is unable to pump blood at a rate proportional to the body’s need for oxygen or when this function leads to elevated cardiac chamber filling pressures (cardiogenic pulmonary edema). Despite our sophisticated knowledge of heart failure, even so-called ejection fraction-preserved heart failure has high rates of mortality and morbidity. So, novel therapies are sorely needed. This review discusses current standard therapies for heart failure and launches an exploration into emerging novel treatments on the heels of recently-approved sacubitril and ivbradine. For example, Vasoactive Intestinal Peptide (VIP) is protective of the heart, so in the absence of VIP, VIP knockout mice have dysregulation in key heart failure genes: 1) Force Generation and Propagation; 2) Energy Production and Regulation; 3) Ca+2 Cycling; 4) Transcriptional Regulators. VIP administration leads to coronary dilation in human subjects. In heart failure patients, VIP levels are elevated as a plausible endogenous protective effect. With the development of elastin polymers to stabilize VIP and prevent its degradation, VIP may therefore have a chance to satisfy the unmet need as a potential treatment for acute heart failure. PMID:26512208

  14. Decompensated heart failure

    PubMed Central

    Mangini, Sandrigo; Pires, Philippe Vieira; Braga, Fabiana Goulart Marcondes; Bacal, Fernando

    2013-01-01

    ABSTRACT Heart failure is a disease with high incidence and prevalence in the population. The costs with hospitalization for decompensated heart failure reach approximately 60% of the total cost with heart failure treatment, and mortality during hospitalization varies according to the studied population, and could achieve values of 10%. In patients with decompensated heart failure, history and physical examination are of great value for the diagnosis of the syndrome, and also can help the physician to identify the beginning of symptoms, and give information about etiology, causes and prognosis of the disease. The initial objective of decompensated heart failure treatment is the hemodynamic and symptomatic improvement preservation and/or improvement of renal function, prevention of myocardial damage, modulation of the neurohormonal and/or inflammatory activation and control of comorbidities that can cause or contribute to progression of the syndrome. According to the clinical-hemodynamic profile, it is possible to establish a rational for the treatment of decompensated heart failure, individualizing the proceedings to be held, leading to reduction in the period of hospitalization and consequently reducing overall mortality. PMID:24136770

  15. Troponins in heart failure.

    PubMed

    Omland, T; Røsjø, H; Giannitsis, E; Agewall, S

    2015-03-30

    The signs and symptoms of heart failure are frequently unspecific and correlate poorly with objective indices of cardiac function. Objective assessment of cardiac function by echocardiography or other imaging modalities also correlate poorly with symptomatic status and functional capacity. Accordingly, there is a need for circulating biomarkers that can provide incremental diagnostic and prognostic information to the existing armamentarium of tests. The introduction of more sensitive assays that allow determination of very low circulating concentrations of the myofibrillar proteins cardiac troponin I and T has not only resulted in improved diagnostic accuracy in the setting of acute coronary syndromes. The high sensitivity assays have also shown that cardiac troponins are frequently found chronically circulating in a variety of acute and chronic, cardiac and non-cardiac disease conditions, including acute heart failure and chronic symptomatic and asymptomatic left ventricular dysfunction. Cardiac troponin I and T provide may provide clinically useful prognostic information both concerning the future risk of developing heart failure in asymptomatic subjects and the risk of fatal events and hospital admissions in those with already established heart failure This review summarizes current literature on the clinical performance and utility of cardiac troponin measurements as diagnostic and prognostic tools in patients with symptomatic heart failure, as well as in those with asymptomatic left ventricular dysfunction, and clinical phenotypes at high risk for developing heart failure, including stable coronary artery disease, left ventricular hypertrophy, and aortic stenosis.

  16. Pathophysiology of Heart Failure.

    PubMed

    Tanai, Edit; Frantz, Stefan

    2015-12-15

    Heart failure is considered an epidemic disease in the modern world affecting approximately 1% to 2% of adult population. It presents a multifactorial, systemic disease, in which--after cardiac injury--structural, neurohumoral, cellular, and molecular mechanisms are activated and act as a network to maintain physiological functioning. These coordinated, complex processes lead to excessive volume overload, increased sympathetic activity, circulation redistribution, and result in different, parallel developing clinical signs and symptoms. These signs and symptoms sum up to an unspecific clinical picture; thus invasive and noninvasive diagnostic tools are used to get an accurate diagnosis and to specify the underlying cause. The most important, outcome determining factor in heart failure is its constant progression. Constant optimizing of pharmatherapeutical regimes, novel targets, and fine regulation of these processes try to keep these compensatory mechanisms in a physiological range. Beside pharmacological therapy, interventional and surgical therapy options give new chances in the management of heart failure. For the optimization and establishment of these and novel therapeutical approaches, complete and comprehensive understanding of the underlying mechanisms is essentially needed. Besides diagnosis and treatment, efforts should be made for better prevention in heart failure by treatment of risk factors, or identifying and following risk groups. This summary of the pathophysiology of heart failure tries to give a compact overview of basic mechanisms and of the novel unfolding, progressive theory of heart failure to contribute to a more comprehensive knowledge of the disease.

  17. Pathophysiology of Heart Failure.

    PubMed

    Tanai, Edit; Frantz, Stefan

    2015-01-01

    Heart failure is considered an epidemic disease in the modern world affecting approximately 1% to 2% of adult population. It presents a multifactorial, systemic disease, in which--after cardiac injury--structural, neurohumoral, cellular, and molecular mechanisms are activated and act as a network to maintain physiological functioning. These coordinated, complex processes lead to excessive volume overload, increased sympathetic activity, circulation redistribution, and result in different, parallel developing clinical signs and symptoms. These signs and symptoms sum up to an unspecific clinical picture; thus invasive and noninvasive diagnostic tools are used to get an accurate diagnosis and to specify the underlying cause. The most important, outcome determining factor in heart failure is its constant progression. Constant optimizing of pharmatherapeutical regimes, novel targets, and fine regulation of these processes try to keep these compensatory mechanisms in a physiological range. Beside pharmacological therapy, interventional and surgical therapy options give new chances in the management of heart failure. For the optimization and establishment of these and novel therapeutical approaches, complete and comprehensive understanding of the underlying mechanisms is essentially needed. Besides diagnosis and treatment, efforts should be made for better prevention in heart failure by treatment of risk factors, or identifying and following risk groups. This summary of the pathophysiology of heart failure tries to give a compact overview of basic mechanisms and of the novel unfolding, progressive theory of heart failure to contribute to a more comprehensive knowledge of the disease. PMID:26756631

  18. Team management of failure to thrive.

    PubMed

    Peterson, K E; Washington, J; Rathbun, J M

    1984-07-01

    A multidisciplinary team approach to treatment of failure to thrive in infancy and early childhood permits the simultaneous consideration of nutritional, medical, and psychosocial risk factors associated with this complex syndrome. The registered dietitian works with the physician, nurse, and social worker to provide an integrated evaluation of nutrition history, feeding patterns, medical status, social situation, developmental level, and interactional qualities of the child with failure to thrive. Nutritional management of failure to thrive emphasizes: (a) ongoing assessment of nutritional status and rate of catch-up growth, including regular collection of anthropometric measurements; (b) provision of energy and protein in amounts sufficient to meet requirements for catch-up growth; and (c) concrete, individualized nutrition instruction. Long-term follow-up at regular intervals in coordination with other members of the failure-to-thrive team provides the opportunity to reinforce nutrition instruction and to reassess and adapt meal plans to meet the growing child's changing nutritional needs.

  19. Risk and Recovery from Course Failure in the Early Years of High School.

    ERIC Educational Resources Information Center

    Roderick, Melissa; Camburn, Eric

    1999-01-01

    Examined patterns in the relative risk of course failure and recovery from failure over the first four semesters of high school for students in the Chicago, Illinois, school system, showing how failure rates vary as a function of race, ethnicity, gender, age, and prior performance. Results for 27,612 students show that few recover from failure,…

  20. Strategies for the prevention of continuous positive airway pressure failure.

    PubMed

    Sahni, Rakesh; Schiaratura, Maria; Polin, Richard A

    2016-06-01

    Progress in neonatal intensive care is closely linked to improvements in the management of respiratory failure in preterm infants. Current modalities of respiratory support range from the more benign continuous positive airway pressure (CPAP) to various modes of mechanical ventilation. Data from recent randomized control trials suggest that the use of nasal (n)CPAP as the initial mode of respiratory support in critically ill very low birth weight infants is associated with a lower incidence of chronic lung disease. The practice of early initiation of nasal-prong CPAP in all spontaneously breathing infants at Columbia University has resulted in very low rates of chronic lung disease for decades. Many institutions have attempted to replicate the practices and results at Columbia University. However, success rates with nCPAP are highly variable, which may in part be attributable to how well it is utilized. With recent renewed interest in non-invasive respiratory support, particularly bubble nCPAP, it is essential to evaluate strategies for the prevention of CPAP failure. This review discusses strategies that address these issues and shares the practical aspects for replicating success with bubble nCPAP. In addition, it reviews desirable features, major components, and physiological consequences of various bubble CPAP systems along with clinical experience of CPAP use. PMID:26936186

  1. Immunity-based detection, identification, and evaluation of aircraft sub-system failures

    NASA Astrophysics Data System (ADS)

    Moncayo, Hever Y.

    This thesis describes the design, development, and flight-simulation testing of an integrated Artificial Immune System (AIS) for detection, identification, and evaluation of a wide variety of sensor, actuator, propulsion, and structural failures/damages including the prediction of the achievable states and other limitations on performance and handling qualities. The AIS scheme achieves high detection rate and low number of false alarms for all the failure categories considered. Data collected using a motion-based flight simulator are used to define the self for an extended sub-region of the flight envelope. The NASA IFCS F-15 research aircraft model is used and represents a supersonic fighter which include model following adaptive control laws based on non-linear dynamic inversion and artificial neural network augmentation. The flight simulation tests are designed to analyze and demonstrate the performance of the immunity-based aircraft failure detection, identification and evaluation (FDIE) scheme. A general robustness analysis is also presented by determining the achievable limits for a desired performance in the presence of atmospheric perturbations. For the purpose of this work, the integrated AIS scheme is implemented based on three main components. The first component performs the detection when one of the considered failures is present in the system. The second component consists in the identification of the failure category and the classification according to the failed element. During the third phase a general evaluation of the failure is performed with the estimation of the magnitude/severity of the failure and the prediction of its effect on reducing the flight envelope of the aircraft system. Solutions and alternatives to specific design issues of the AIS scheme, such as data clustering and empty space optimization, data fusion and duplication removal, definition of features, dimensionality reduction, and selection of cluster/detector shape are also

  2. Enhanced Component Performance Study: Air-Operated Valves 1998–2012

    SciTech Connect

    T. E. Wierman

    2013-10-01

    This report presents an enhanced performance evaluation of air-operated valves (AOVs) at U.S. commercial nuclear power plants. The data used in this study are based on the operating experience failure reports from fiscal year 1998 through 2012 for the component reliability as reported in the Equipment Performance and Information Exchange (EPIX). Results (beta distributions for failure probabilities upon demand and gamma distributions for rates) are used as inputs to the U.S. Nuclear Regulatory Commission standardized plant analysis risk models of U.S. commercial nuclear power plants. The AOV failure modes considered are failure-to-open/close, failure to operate or control, and spurious operation. The component reliability estimates and the reliability data are trended for the most recent 10-year period while yearly estimates for reliability are provided for the entire active period. No statistically significant increasing trends were identified in the AOV results. Statistically significant decreasing trends were identified in two areas: AOV operation demands less than or equal to 20 demands per year and greater than 20 demands.

  3. Two-parameter Failure Model Improves Time-independent and Time-dependent Failure Predictions

    SciTech Connect

    Huddleston, R L

    2004-01-27

    A new analytical model for predicting failure under a generalized, triaxial stress state was developed by the author and initially reported in 1984. The model was validated for predicting failure under elevated-temperature creep-rupture conditions. Biaxial data for three alloy steels, Types 304 and 316 stainless steels and Inconel 600, demonstrated two to three orders of magnitude reduction in the scatter of predicted versus observed creep-rupture times as compared to the classical failure models of Mises, Tresca, and Rankine. In 1990, the new model was incorporated into American Society of Mechanical Engineers (ASME) Code Case N47-29 for design of components operating under creep-rupture conditions. The current report provides additional validation of the model for predicting failure under time-independent conditions and also outlines a methodology for predicting failure under cyclic, time-dependent, creep-fatigue conditions. The later extension of the methodology may have the potential to improve failure predictions there as well. These results are relevant to most design applications, but they have special relevance to high-performance design applications such as components for high-pressure equipment, nuclear reactors, and jet engines.

  4. GCS component development cycle

    NASA Astrophysics Data System (ADS)

    Rodríguez, Jose A.; Macias, Rosa; Molgo, Jordi; Guerra, Dailos; Pi, Marti

    2012-09-01

    The GTC1 is an optical-infrared 10-meter segmented mirror telescope at the ORM observatory in Canary Islands (Spain). First light was at 13/07/2007 and since them it is in the operation phase. The GTC control system (GCS) is a distributed object & component oriented system based on RT-CORBA8 and it is responsible for the management and operation of the telescope, including its instrumentation. GCS has used the Rational Unified process (RUP9) in its development. RUP is an iterative software development process framework. After analysing (use cases) and designing (UML10) any of GCS subsystems, an initial component description of its interface is obtained and from that information a component specification is written. In order to improve the code productivity, GCS has adopted the code generation to transform this component specification into the skeleton of component classes based on a software framework, called Device Component Framework. Using the GCS development tools, based on javadoc and gcc, in only one step, the component is generated, compiled and deployed to be tested for the first time through our GUI inspector. The main advantages of this approach are the following: It reduces the learning curve of new developers and the development error rate, allows a systematic use of design patterns in the development and software reuse, speeds up the deliverables of the software product and massively increase the timescale, design consistency and design quality, and eliminates the future refactoring process required for the code.

  5. Low dose failures of hardened DC-DC power converters

    NASA Technical Reports Server (NTRS)

    Lehman, J.; Yui, C.; Rax, B. G.; Miyahira, T. F.; Weideman, M.; Schrick, P.; Swift, G. M.; Johnston, A. H.

    2002-01-01

    Box-level total dose testing of the FOG (Fiber Optic Gyro) by IXSEA at ESA's GammabeamFacility were abruptly terminated at 8krad (Si) due to catastrophic failure (complete shutdown). This was unexpected because all components within the gyro were supposedly radiation tolerant. Further testing showed that the components responsible for the failure were two DC-DC converters, manufactured by Interpoint, that stopped regulating shortly before shutdown. This paper summarizes diagnostic test results for the converters to determine the underlying cause of the unexpected failure at low levels of radiation.

  6. Angular-Rate Estimation Using Quaternion Measurements

    NASA Technical Reports Server (NTRS)

    Azor, Ruth; Bar-Itzhack, Y.; Deutschmann, Julie K.; Harman, Richard R.

    1998-01-01

    In most spacecraft (SC) there is a need to know the SC angular rate. Precise angular rate is required for attitude determination, and a coarse rate is needed for attitude control damping. Classically, angular rate information is obtained from gyro measurements. These days, there is a tendency to build smaller, lighter and cheaper SC, therefore the inclination now is to do away with gyros and use other means and methods to determine the angular rate. The latter is also needed even in gyro equipped satellites when performing high rate maneuvers whose angular-rate is out of range of the on board gyros or in case of gyro failure. There are several ways to obtain the angular rate in a gyro-less SC. When the attitude is known, one can differentiate the attitude in whatever parameters it is given and use the kinematics equation that connects the derivative of the attitude with the satellite angular-rate and compute the latter. Since SC usually utilize vector measurements for attitude determination, the differentiation of the attitude introduces a considerable noise component in the computed angular-rate vector.

  7. Synergistic Failure of BWR Internals

    SciTech Connect

    Ware, Arthur Gates; Chang, T-Y

    1999-10-01

    Boiling Water Reactor (BWR) core shrouds and other reactor internals important to safety are experiencing intergranular stress corrosion cracking (IGSCC). The United States Nuclear Regulatory Commission has followed the problem, and as part of its investigations, contracted with the Idaho National Engineering and Environmental Laboratory to conduct a risk assessment. The overall project objective is to assess the potential consequences and risks associated with the failure of IGSCC-susceptible BWR vessel internals, with specific consideration given to potential cascading and common mode effects. An initial phase has been completed in which background material was gathered and evaluated, and potential accident sequences were identified. A second phase is underway to perform a simplified, quantitative probabilistic risk assessment on a representative high-power BWR/4. Results of the initial study conducted on the jet pumps show that any cascading failures would not result in a significant increase in the core damage frequency. The methodology is currently being extended to other major reactor internals components.

  8. BIOASSAY VESSEL FAILURE ANALYSIS

    SciTech Connect

    Vormelker, P

    2008-09-22

    Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest cross-section of the octagonal vessel. No material flaws were found in the vessel that would impair its structural performance. Content weight should be minimized to reduce operating temperature and pressure. Outer vessel life is dependent on actual temperature exposure. Since thermal aging of the vessels can be detrimental to their performance, it was recommended that the vessels be used for a limited number of cycles to be determined by additional testing.

  9. Judicial failure to thrive.

    PubMed

    Stern, H P; Casey, P H

    1984-06-01

    The case of a toddler who developed nonorganic failure to thrive during the course of a custody determination is reported. The child demonstrated physical, emotional, and developmental aspects of failure to thrive. These signs correlated with custody ordered by the judge, during which time the child's care was alternated between parents. The symptoms resolved when the child was in the hospital and when provided stable care by his grandmother. With the increasing frequency of divorce, failure to thrive resulting from judicial decisions will probably increase. Physicians should monitor these children carefully in order to prevent serious psychosocial complications. The judicial system should expedite custody decisions, availing itself of information in child development. PMID:6736261

  10. Common Cause Failure Modes

    NASA Technical Reports Server (NTRS)

    Wetherholt, Jon; Heimann, Timothy J.; Anderson, Brenda

    2011-01-01

    High technology industries with high failure costs commonly use redundancy as a means to reduce risk. Redundant systems, whether similar or dissimilar, are susceptible to Common Cause Failures (CCF). CCF is not always considered in the design effort and, therefore, can be a major threat to success. There are several aspects to CCF which must be understood to perform an analysis which will find hidden issues that may negate redundancy. This paper will provide definition, types, a list of possible causes and some examples of CCF. Requirements and designs from NASA projects will be used in the paper as examples.

  11. Asteroid failure modes due to YORP spin-up: A survey

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Masatoshi; Scheeres, D. J.

    2013-10-01

    We study the first failure mode of real asteroids driven to high spin-rates by the YORP effect. We focus on two failure modes: structural failure and surface shedding. The analysis only considers self-gravity and centrifugal forces. Also, we assume that the body spins in a principal axis mode, has a homogeneous density distribution, is cohesionless, and can be characterized by a friction angle between 30 and 45 degrees. We analyze surface shedding by tracking the dynamical equilibrium points. This mode causes a body to lose material from its extremities due to centrifugal accelerations overcoming gravitational accelerations. Shedding first occurs when one of the equilibrium points reaches the surface. We assume that the original shape is fixed, and thus the analysis provides a conservative condition. This condition does not consider temporary small-scale mass movement like saltation by landslides. We determine structural failure using the upper bound theorem of limit analysis. This failure mode causes a body to catastrophically deform or break into smaller components. The theorem by Holsapple (2008, INT J NONLINEAR MECH) guarantees that for any static surface traction and body force, the yield due to a smooth and convex yield envelope associated with the volume average is identical to the upper bound. We use this theorem with two volume averaging techniques: total volume (Holsapple, 2008, Icarus) and partial volume (Hirabayashi et al., 2013, Apj, submitted). This method is conservative as well. We investigate the failure modes for 21 shape models, including 1999KW4, Betulia, Geographos, Nereus, Itokawa, and 1996HW1. We can classify three shape morphologies in terms of their internal properties and failure modes: spheroidal, ellipsoidal, and bifurcated. Spheroidal bodies such as 1999KW4 and Betulia undergo structural failure first, not surface shedding. Ellipsoidal bodies such as Geographos and Nereus can experience either surface shedding or structural failure

  12. Reconfigurable control of aircraft undergoing sensor and actuator failures

    NASA Astrophysics Data System (ADS)

    Bajpai, Gaurav

    2001-07-01

    Significant number of fatal aircraft accidents in recent years have been linked to component failures. With the predicted increase in air traffic these numbers are likely to increase. With reduction of fatal accidents as motivation, this dissertation investigates design of fault tolerant control systems for aircrafts undergoing sensor and/or actuator failures. Given that the nominal controller may perform inadequately in the event of sensors and/or actuator failure, the feasible approach for such a control scheme is to predesign various controllers anticipating these failures and then switching to an appropriate controller when the failure occurs. This is enabled by the available redundancy in sensing and actuation and allows the system to perform adequately even when these failures occur. The predesign of controllers for sensor and actuator failures is considered. Sensor failures are easily accommodated if certain detectability conditions are met. However, the predesign for actuator failures is not trivial as the position at which the actuators fail is not known a priori. It is shown that this problem can be tackled by reducing it to the classical control problem of disturbance decoupling, in which, the functional control enables the steady state output of dynamical system to reject any disturbance due to the failed actuators. For linear systems, conditions for existence of a controller capable of accommodating these failures can be understood in geometric terms and calculations are linked to solvability of coupled matrix equations. Although control design for aircrafts is done using linear techniques, failures can cause excursions into nonlinear regimes due to ensuing changes in the flight conditions. This dissertation also uses the recent results in the nonlinear regulator theory to address actuator failures in nonlinear systems. The utility of design techniques is illustrated using flight control examples with failures. The symbolic computational tools are

  13. Screening process failures for hepatocellular carcinoma.

    PubMed

    Singal, Amit G; Marrero, Jorge A; Yopp, Adam

    2014-03-01

    More than 60% of patients with hepatocellular carcinoma (HCC) are diagnosed at a late stage, suggesting potential breakdowns in the HCC screening process. Understanding which steps in the screening process are not being performed is essential for designing effective interventions. To characterize HCC screening process failures, a retrospective cohort study of patients with cirrhosis diagnosed with HCC at a large urban safety-net hospital was conducted between 2005 and 2012. Screening process failures during the year before HCC diagnosis were characterized into 3 categories: absence of surveillance, failure of detection, and delayed follow-up. Univariate and multivariate analyses were performed to identify predictors of screening process failures. A total of 185 patients with cirrhosis and HCC were identified, of whom 91 (49%) were diagnosed at an early stage (Barcelona Clinic Liver Cancer system stage A). Only 16 (8.6%) patients successfully completed the screening process. Absence of surveillance was the most common screening process failure, found in 75.7% of all patients, and was associated with trends toward lower rates of early tumor detection (odds ratio, 0.51; 95% CI, 0.23-1.09) and worse overall survival (hazard ratio, 0.79; 95% CI, 0.49-1.25). Failure of detection and delayed follow-up were found in 11.4% and 2.7% of patients, respectively.

  14. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.; Bates, J. Lambert

    1980-01-01

    A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

  15. Diagnosis and management of baroreflex failure

    NASA Technical Reports Server (NTRS)

    Robertson, D.

    1995-01-01

    Baroreflex failure has a range of presentations, varying from the acute onset of a hypertensive crisis to a chronically volatile blood pressure and heart rate with hypertensive surges in response to stress, punctuated by periods of normal or even low blood pressure during rest. Differentiating this syndrome from other causes of labile hypertension is essential in devising effective treatment.

  16. Update on ivabradine for heart failure.

    PubMed

    Borer, Jeffrey S; Tavazzi, Luigi

    2016-07-01

    Despite dramatic advances in therapy for heart failure (HF) during the past 3 decades, hospitalization and mortality rates remain relatively high. In recent decades, it has become apparent that HF is divisible into two equally lethal but pathophysiologically different sub-classes, the first comprising patients with LV systolic dysfunction [heart failure with reduced ejection fraction (HFrEF)] and the other, approximately equal in size, involving patients with "preserved" systolic function [heart failure with preserved ejection fraction (HFpEF)]. Evidence-based event reducing therapy currently is available only for HFrEF. With the completion of seminal trials of beta blockers, now part of standard therapy for HFrEF, it was apparent that heart rate slowing is an underlying basis of clinical effectiveness of HFrEF therapy. With the discovery of the "f current" that modulates the slope of spontaneous diastolic depolarization of the sino-atrial node, a non-beta blockade approach to heart rate slowing became available. Ivabradine, the first FDA-approved f-current blocker for HFrEF, markedly reduces hospitalizations for worsening heart failure, while also progressively reducing mortality as pre-therapy heart rate increases, and also promotes beneficial left ventricular remodeling, improves health-related quality of life and is effective despite a wide range of comorbidities. The drug is well tolerated and adverse effects are relatively few. Ivabradine represents an important addition to the armamentarium for mitigation of HFrEF. PMID:26934996

  17. Patterns of failure following curative resection of gastric carcinoma

    SciTech Connect

    Landry, J.; Tepper, J.E.; Wood, W.C.; Moulton, E.O.; Koerner, F.; Sullinger, J. )

    1990-12-01

    To identify patterns of failure following curative resection of gastric carcinoma, the records of 130 patients undergoing resection with curative intent at the Massachusetts General Hospital were reviewed. The total local-regional failure rate was 38% (49/130 patients), with 21 patients having local-regional failure alone and 28 patients having local-regional failure and distant metastases. The incidence of local failure rose with the more advanced stages of disease. Tumors staged B2, B3, C2, and C3 had local-regional failure rates in excess of 35%. This group of patients might benefit from adjuvant radiation therapy to the tumor bed and regional lymphatics. Local-regional failure rate was highest in the anastomosis or stump 33/130 (25%), followed by the stomach bed 27/130 (21%). The overall incidence of distant metastases was 52% (67/130 patients) and rose in the more advanced disease stages. Tumors staged B2, B3, C2, and C3 had rates of distant metastases greater than 50%. Sixty-one patients (77%) had failure in the abdomen (liver, peritoneal surface, adrenal, kidney, and spleen, but excluding tumor bed, anastomosis, or regional nodes). Patients with Stage B2, B3, C2, and C3 tumors had total abdominal failure rates greater than 40%. The highest failure rates in the liver were in Stages B3 and C3, in which the subsequent development of liver metastasis was 40% and 47%, respectively. Peritoneal seeding occurred in 30/130 (23%) of patients and was highest in Stages C2 and C3, with rates of 27% and 41%, respectively.

  18. A novel mathematical setup for fault tolerant control systems with state-dependent failure process

    NASA Astrophysics Data System (ADS)

    Chitraganti, S.; Aberkane, S.; Aubrun, C.

    2014-12-01

    In this paper, we consider a fault tolerant control system (FTCS) with state- dependent failures and provide a tractable mathematical model to handle the state-dependent failures. By assuming abrupt changes in system parameters, we use a jump process modelling of failure process and the fault detection and isolation (FDI) process. In particular, we assume that the failure rates of the failure process vary according to which set the state of the system belongs to.

  19. Living with Heart Failure

    MedlinePlus

    ... should be. This includes advice on daily activities, work, leisure time, sex, and exercise. Your level of activity will depend on the stage of your heart failure (how severe it is). Keep all of your ... to get tests and lab work. Your doctor needs the results of these tests ...

  20. Failure Free Reading.

    ERIC Educational Resources Information Center

    Education Commission of the States, Denver, CO.

    This paper provides an overview of Failure Free Reading, a program with the primary goal of providing a basic understanding of the reading process to students in grades K-12 with pronounced reading difficulty and move them into traditional reading programs. The program is targeted to and most effective with at-risk and English as a Second Language…