Analysing recurrent hospitalizations in heart failure: a review of statistical methodology, with application to CHARM-Preserved.

PubMed

Rogers, Jennifer K; Pocock, Stuart J; McMurray, John J V; Granger, Christopher B; Michelson, Eric L; Östergren, Jan; Pfeffer, Marc A; Solomon, Scott D; Swedberg, Karl; Yusuf, Salim

2014-01-01

Heart failure is characterized by recurrent hospitalizations, but often only the first event is considered in clinical trial reports. In chronic diseases, such as heart failure, analysing all events gives a more complete picture of treatment benefit. We describe methods of analysing repeat hospitalizations, and illustrate their value in one major trial. The Candesartan in Heart failure Assessment of Reduction in Mortality and morbidity (CHARM)-Preserved study compared candesartan with placebo in 3023 patients with heart failure and preserved systolic function. The heart failure hospitalization rates were 12.5 and 8.9 per 100 patient-years in the placebo and candesartan groups, respectively. The repeat hospitalizations were analysed using the Andersen-Gill, Poisson, and negative binomial methods. Death was incorporated into analyses by treating it as an additional event. The win ratio method and a method that jointly models hospitalizations and mortality were also considered. Using repeat events gave larger treatment benefits than time to first event analysis. The negative binomial method for the composite of recurrent heart failure hospitalizations and cardiovascular death gave a rate ratio of 0.75 [95% confidence interval (CI) 0.62-0.91, P = 0.003], whereas the hazard ratio for time to first heart failure hospitalization or cardiovascular death was 0.86 (95% CI 0.74-1.00, P = 0.050). In patients with preserved EF, candesartan reduces the rate of admissions for worsening heart failure, to a greater extent than apparent from analysing only first hospitalizations. Recurrent events should be routinely incorporated into the analysis of future clinical trials in heart failure. © 2013 The Authors. European Journal of Heart Failure © 2013 European Society of Cardiology.

Cerebrospinal Fluid Shunting Complications in Children

PubMed Central

Hanak, Brian W.; Bonow, Robert H.; Harris, Carolyn A.; Browd, Samuel R.

2018-01-01

Although cerebrospinal fluid (CSF) shunt placement is the most common procedure performed by pediatric neurosurgeons, shunts remain among the most failure-prone life-sustaining medical devices implanted in modern medical practice. This article provides an overview of the mechanisms of CSF shunt failure for the 3 most commonly employed definitive CSF shunts in the practice of pediatric neurosurgery: ventriculoperitoneal, ventriculopleural, and ventriculoatrial. The text has been partitioned into the broad modes of shunt failure: obstruction, infection, mechanical shunt failure, overdrainage, and distal catheter site-specific failures. Clinical management strategies for the various modes of shunt failure are discussed as are research efforts directed towards reducing shunt complication rates. As it is unlikely that CSF shunting will become an obsolete procedure in the foreseeable future, it is incumbent on the pediatric neurosurgery community to maintain focused efforts to improve our understanding of and management strategies for shunt failure and shunt-related morbidity. PMID:28249297

The Development of Stem Cell-Based Treatment for Liver Failure.

PubMed

Zhu, Tiantian; Li, Yuwen; Guo, Yusheng; Zhu, Chuanlong

2017-01-01

Liver failure is a devastating clinical syndrome with a persistently mortality rate despite advanced care. Orthotopic liver transplantation protected patients from hepatic failure. Yet, limitations including postoperative complications, high costs, and shortages of donor organs defect its application. The development of stem cell therapy complements the deficiencies of liver transplantation, due to the inherent ability of stem cells to proliferate and differentiate. Understand the source of stem cells, as well as the advantages and disadvantages of stem cell therapy. Based on published papers, we discussed the cell sources and therapeutic effect of stem cells. We also summarized the pros and cons, as well as optimization of stem cell-based treatment. Finally outlook future prospects of stem cell therapy. Stem cells may be harvested from a variety of human tissues, and then used to promote the convalescence of hepatocellular function. The emergence of the co-cultured system, tissueengineered technology and genetic modfication has further enhanced the functionality of stem cells. However, the tumorigenicity, the low survival rate and the scarcity of long-term treatment effect are obstacles for the further development of stem cell therapy. In this review, we highlight current research findings and present the future prospects in the area of stem cell-based treatment for liver failure. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Surgical approach to end-stage heart failure.

PubMed

Klotz, Stefan; Scheld, Hans H

2011-02-01

End-stage heart failure is a challenging disease with growing incidence. With decreasing heart transplant rates worldwide organ preserving therapies become, again, of interest. The purpose of the present review is to examine the potential challenges of surgical therapies in patients with end-stage heart failure. The gold-standard for end-stage heart failure is and will be cardiac transplantation. However, due to organ shortage this therapy is limited to a few patients. Therefore implantation of ventricular assist devices (VADs) or long-term minimal-invasive partial support devices will increase. Improvements in device design with smaller devices, easier implantation techniques, and modified anticoagulation outcome and long-term success will likely improve. In addition, good quality of life as destination therapy is almost available. Organ conservation surgery (coronary artery bypass grafting and surgical ventricular restoration or surgical repair of mitral valve regurgitation) in end-stage heart failure patients could not prove the expected results. Transcatheter or minimal-invasive approaches of these therapies might become routine in the near future. Due to the overwhelming outcome rates, cardiac transplantation is the most established surgical therapy for end-stage heart failure. VAD therapy is increasing and minimized VADs might further open the market for destination therapy/permanent support.

Is it possible to identify a trend in problem/failure data

NASA Technical Reports Server (NTRS)

Church, Curtis K.

1990-01-01

One of the major obstacles in identifying and interpreting a trend is the small number of data points. Future trending reports will begin with 1983 data. As the problem/failure data are aggregated by year, there are just seven observations (1983 to 1989) for the 1990 reports. Any statistical inferences with a small amount of data will have a large degree of uncertainty. Consequently, a regression technique approach to identify a trend is limited. Though trend determination by failure mode may be unrealistic, the data may be explored for consistency or stability and the failure rate investigated. Various alternative data analysis procedures are briefly discussed. Techniques that could be used to explore problem/failure data by failure mode are addressed. The data used are taken from Section One, Space Shuttle Main Engine, of the Calspan Quarterly Report dated April 2, 1990.

Spacecraft and propulsion technician error

NASA Astrophysics Data System (ADS)

Schultz, Daniel Clyde

Commercial aviation and commercial space similarly launch, fly, and land passenger vehicles. Unlike aviation, the U.S. government has not established maintenance policies for commercial space. This study conducted a mixed methods review of 610 U.S. space launches from 1984 through 2011, which included 31 failures. An analysis of the failure causal factors showed that human error accounted for 76% of those failures, which included workmanship error accounting for 29% of the failures. With the imminent future of commercial space travel, the increased potential for the loss of human life demands that changes be made to the standardized procedures, training, and certification to reduce human error and failure rates. Several recommendations were made by this study to the FAA's Office of Commercial Space Transportation, space launch vehicle operators, and maintenance technician schools in an effort to increase the safety of the space transportation passengers.

Falls in Patients With Heart Failure: A Systematic Review.

PubMed

Lee, Kayoung; Pressler, Susan J; Titler, Marita

Many heart failure patients show fall-related signs/symptoms including postural hypotension, cerebellar injury, and cognitive impairments. Falls contribute to injuries, increased healthcare use, and death, but falls have been understudied in this population. The purpose of this review is to identify fall rates, fall injuries, and risk factors for falls in heart failure patients. A systematic literature review was conducted using MEDLINE, CINAHL, PubMed, PsycINFO, and Cochrane Library to identify publications from August 1973 to June 2013. Keywords were accidental falls, heart failure, fall rates, fall injuries, and fall risk. Inclusion criteria were publications that were primary data based, included heart failure sample, had falls/fall risk as study variables, and were written in English language. Exclusion criteria were quality improvement/evaluation, case reports/studies, news, opinions, narrative reviews, meeting reports, reflections, and letters to editors. Data were abstracted using a standardized data collection form. Four publications met the inclusion criteria. In the first study, fall rate was 43%, which is higher than the fall rates among community-dwelling older adults. Fall-related injuries were not examined in any of studies. Benzodiazepines and digoxin were identified as medications that increased risk of falls in 1 case-control study. Loop diuretics were not significantly associated with falls in 1 cohort study. In the fourth study, patients who had poor gait and balance were at greater risk of falling. Future studies are needed to determine factors associated with falls, characterize injuries resulting from falls, and most importantly design testable interventions to prevent falls in heart failure patients.

Clinical risk factors related to failures with zirconia-based restorations: an up to 9-year retrospective study.

PubMed

Koenig, Vinciane; Vanheusden, Alain J; Le Goff, Stéphane O; Mainjot, Amélie K

2013-12-01

The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis. 147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n=46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique. The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan-Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p=0.0048), the presence of a ceramic restoration as an antagonist (p=0.013), the presence of parafunctional activity (p=0.018), and the presence of implants as support (p=0.026). The implant abutments success rate was 100%. The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies. Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Recurrent achalasia treated with Heller myotomy: A review of the literature

PubMed Central

Wang, Lan; Li, You-Ming

2008-01-01

AIM: To evaluate the efficacy and safety of Heller myotomy (HM) for recurrent achalasia, performed after different methods of first-line treatment. METHODS: We searched for studies published in PubMed from 1966 to March 2008 on treatment of recurrent achalasia with HM after failure with different methods of first-line treatment. The efficacy of HM was assessed by a pooled estimate of response rate with individual studies weighted proportionally to sample size. RESULTS: Sixteen studies were eligible and included in the review. The results showed that HM has a better remission rate for recurrent achalasia after failure of HM [weighted mean (SD)] of 86.9% (21.8%) compared with 81.6% (23.8%) for pneumatic dilatation (PD). One study evaluated the efficacy of HM after failure of PD combined with botulinum toxin injection (83%). The most common complications were perforation and gastroesophageal reflux. CONCLUSION: HM has the best efficacy in patients with recurrent achalasia who were treated with HM as first-line treatment. Future studies should focus on how to increase the success rate and decrease the complications of HM. PMID:19084921

Procrastination, consideration of future consequences, and episodic future thinking.

PubMed

Rebetez, Marie My Lien; Barsics, Catherine; Rochat, Lucien; D'Argembeau, Arnaud; Van der Linden, Martial

2016-05-01

Despite the intrinsic temporal nature of procrastination, little research has examined the link between this form of self-regulatory failure and the consideration of future consequences, and no study has addressed the link between procrastination and episodic future thinking. The aim of the present study was to explore these relationships. Participants were asked to project themselves into possible future events and to rate the amount of sensory-perceptual details and autonoetic consciousness associated with their representations. They were also asked to complete questionnaires that assessed procrastination, the consideration of future consequences, and negative affect. Results showed that both the consideration of future consequences and episodic future thinking were associated with procrastination, and in particular with procrastination-related decision making abilities and procrastination-related motivational dispositions, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

Failure and life cycle evaluation of watering valves.

PubMed

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

2011-09-01

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.

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

Implementation of predictive data mining techniques for identifying risk factors of early AVF failure in hemodialysis patients.

PubMed

Rezapour, Mohammad; Khavanin Zadeh, Morteza; Sepehri, Mohammad Mehdi

2013-01-01

Arteriovenous fistula (AVF) is an important vascular access for hemodialysis (HD) treatment but has 20-60% rate of early failure. Detecting association between patient's parameters and early AVF failure is important for reducing its prevalence and relevant costs. Also predicting incidence of this complication in new patients is a beneficial controlling procedure. Patient safety and preservation of early AVF failure is the ultimate goal. Our research society is Hasheminejad Kidney Center (HKC) of Tehran, which is one of Iran's largest renal hospitals. We analyzed data of 193 HD patients using supervised techniques of data mining approach. There were 137 male (70.98%) and 56 female (29.02%) patients introduced into this study. The average of age for all the patients was 53.87 ± 17.47 years. Twenty eight patients had smoked and the number of diabetic patients and nondiabetics was 87 and 106, respectively. A significant relationship was found between "diabetes mellitus," "smoking," and "hypertension" with early AVF failure in this study. We have found that these mentioned risk factors have important roles in outcome of vascular surgery, versus other parameters such as "age." Then we predicted this complication in future AVF surgeries and evaluated our designed prediction methods with accuracy rates of 61.66%-75.13%.

Predictors of incident heart failure in patients after an acute coronary syndrome: The LIPID heart failure risk-prediction model.

PubMed

Driscoll, Andrea; Barnes, Elizabeth H; Blankenberg, Stefan; Colquhoun, David M; Hunt, David; Nestel, Paul J; Stewart, Ralph A; West, Malcolm J; White, Harvey D; Simes, John; Tonkin, Andrew

2017-12-01

Coronary heart disease is a major cause of heart failure. Availability of risk-prediction models that include both clinical parameters and biomarkers is limited. We aimed to develop such a model for prediction of incident heart failure. A multivariable risk-factor model was developed for prediction of first occurrence of heart failure death or hospitalization. A simplified risk score was derived that enabled subjects to be grouped into categories of 5-year risk varying from <5% to >20%. Among 7101 patients from the LIPID study (84% male), with median age 61years (interquartile range 55-67years), 558 (8%) died or were hospitalized because of heart failure. Older age, history of claudication or diabetes mellitus, body mass index>30kg/m 2 , LDL-cholesterol >2.5mmol/L, heart rate>70 beats/min, white blood cell count, and the nature of the qualifying acute coronary syndrome (myocardial infarction or unstable angina) were associated with an increase in heart failure events. Coronary revascularization was associated with a lower event rate. Incident heart failure increased with higher concentrations of B-type natriuretic peptide >50ng/L, cystatin C>0.93nmol/L, D-dimer >273nmol/L, high-sensitivity C-reactive protein >4.8nmol/L, and sensitive troponin I>0.018μg/L. Addition of biomarkers to the clinical risk model improved the model's C statistic from 0.73 to 0.77. The net reclassification improvement incorporating biomarkers into the clinical model using categories of 5-year risk was 23%. Adding a multibiomarker panel to conventional parameters markedly improved discrimination and risk classification for future heart failure events. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Effect of dolutegravir functional monotherapy on HIV-1 virological response in integrase strand transfer inhibitor resistant patients.

PubMed

Naeger, Lisa K; Harrington, Patrick; Komatsu, Takashi; Deming, Damon

2016-01-01

VIKING-4 assessed the safety and efficacy of dolutegravir in heavily antiretroviral treatment-experienced patients who had documented integrase strand transfer inhibitor (INSTI) resistance-associated substitutions in their HIV. VIKING-4 had a placebo-controlled 7-day dolutegravir functional monotherapy phase followed by dolutegravir plus an optimized background regimen for 48 weeks. Independent resistance analyses evaluated week 48 virological responses in the VIKING-4 trial based on the presence of baseline INSTI resistance-associated substitutions and baseline dolutegravir phenotypic susceptibility. Response rates at week 48 based on baseline dolutegravir resistance subgroups were compared for the 7-day dolutegravir functional monotherapy arm and placebo-control arm. Additionally, genotypic and phenotypic resistance at day 8 and time of failure was analysed for the virological failures from both arms. Week 48 response rates for VIKING-4 were 23% (3/13) in the 7-day dolutegravir functional monotherapy arm compared with 60% (9/15) in the 7-day placebo arm. Response rates were consistently lower in the dolutegravir functional monotherapy arm across baseline INSTI genotypic and phenotypic subgroups. There was a higher proportion of virological failures in the 7-day dolutegravir functional monotherapy arm (n=6/13; 46%) compared with the 7-day placebo arm (n=3/15; 20%). Additionally, five virological failures in the dolutegravir arm had virus expressing emergent INSTI resistance-associated substitutions compared with two in the placebo arm. Analysis of response rates and resistance emergence in VIKING-4 suggests careful consideration should be given to the duration of functional monotherapy in future studies of highly treatment-experienced patients to reduce the risk of resistance and virological failure.

Teacher response to learning disability: a test of attributional principles.

PubMed

Clark, M D

1997-01-01

Attribution research has identified student ability and effort expended as causes of achievement outcomes that result in differing teacher affect, evaluative feedback, and expectation of future performance. Ninety-seven elementary-school general education teachers (84 women and 13 men) rated their responses to the test failures of hypothetical boys with and without learning disabilities. In most cases, greater reward and less punishment, less anger and more pity, and higher expectations of future failure followed the negative outcomes of the boys with learning disabilities, when compared with their nondisabled ability and effort matches, indicating that learning disability acts as a cause of achievement outcomes in the same way as ability and effort. This pattern of teacher affect and response can send negative messages that are often interpreted as low-ability cues, thus affecting students' self-esteem, sense of competence as learners, and motivation to achieve.

Statistics of acoustic emissions and stress drops during granular shearing using a stick-slip fiber bundle mode

NASA Astrophysics Data System (ADS)

Cohen, D.; Michlmayr, G.; Or, D.

2012-04-01

Shearing of dense granular materials appears in many engineering and Earth sciences applications. Under a constant strain rate, the shearing stress at steady state oscillates with slow rises followed by rapid drops that are linked to the build up and failure of force chains. Experiments indicate that these drops display exponential statistics. Measurements of acoustic emissions during shearing indicates that the energy liberated by failure of these force chains has power-law statistics. Representing force chains as fibers, we use a stick-slip fiber bundle model to obtain analytical solutions of the statistical distribution of stress drops and failure energy. In the model, fibers stretch, fail, and regain strength during deformation. Fibers have Weibull-distributed threshold strengths with either quenched and annealed disorder. The shape of the distribution for drops and energy obtained from the model are similar to those measured during shearing experiments. This simple model may be useful to identify failure events linked to force chain failures. Future generalizations of the model that include different types of fiber failure may also allow identification of different types of granular failures that have distinct statistical acoustic emission signatures.

The safety of sacubitril-valsartan for the treatment of chronic heart failure.

PubMed

Tyler, Jeffrey M; Teerlink, John R

2017-02-01

Sacubitril-valsartan is a combination drug that contains the neprilysin inhibitor sacubitril and angiotensin II receptor blocker valsartan. In 2015, the US Food and Drug Administration approved sacubitril-valsartan for treatment of heart failure patients with reduced ejection fraction and New York Heart Association class II-IV symptoms following a large, Phase III clinical trial (PARADIGM-HF) that demonstrated a 20% reduction in the combined primary end-point of death from cardiovascular cause or hospitalization for heart failure compared to enalapril. Areas covered: This review discusses the clinical efficacy and safety of angiotensin receptor neprilysin inhibitor sacubitril-valsartan in heart failure with reduced ejection fraction. Expert opinion: Based on the PARADIGM-HF trial, sacubitril-valsartan offers compelling reductions in meaningful clinical endpoints, independent of age or severity of disease. The rate of adverse events was comparable between the enalapril and sacubitril-valsartan groups, although the absolute rates are likely underestimated due to the entry criteria and run-in period. Future trials and post-market surveillance are critical to better understand the risk of angioedema in high risk populations, particularly African-Americans, as well as long-term theoretical risks including the potential for increased cerebral amyloid plaque deposition with possible development of neurocognitive disease. Current trials are underway to evaluate potential benefit in patients with heart failure with preserved ejection fraction.

U.S. Governmental Information Operations and Strategic Communications: A Discredited Tool or User Failure? Implications for Future Conflict

DTIC Science & Technology

2013-12-01

U.S. GOVERNMENTAL INFORMATION OPERATIONS AND STRATEGIC COMMUNICATIONS : A DISCREDITED TOOL OR USER FAILURE? IMPLICATIONS FOR FUTURE CONFLICT Steve...TYPE 3. DATES COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE U.S. Governmental Information Operations and Strategic Communications : A ...GOVERNMENTAL INFORMATION OPERATIONS AND STRATEGIC COMMUNICATIONS : A DISCREDITED TOOL OR USER FAILURE? IMPLICATIONS FOR FUTURE CONFLICT Steve Tatham

Residual shear strength variability as a primary control on movement of landslides reactivated by earthquake-induced ground motion: Implications for coastal Oregon, U.S.

USGS Publications Warehouse

Schulz, William H.; Wang, Gonghui

2014-01-01

Most large seismogenic landslides are reactivations of preexisting landslides with basal shear zones in the residual strength condition. Residual shear strength often varies during rapid displacement, but the response of residual shear zones to seismic loading is largely unknown. We used a ring shear apparatus to perform simulated seismic loading tests, constant displacement rate tests, and tests during which shear stress was gradually varied on specimens from two landslides to improve understanding of coseismic landslide reactivation and to identify shear strength models valid for slow gravitational failure through rapid coseismic failure. The landslides we studied represent many along the Oregon, U.S., coast. Seismic loading tests resulted in (1) catastrophic failure involving unbounded displacement when stresses represented those for the existing landslides and (2) limited to unbounded displacement when stresses represented those for hypothetical dormant landslides, suggesting that coseismic landslide reactivation may be significant during future great earthquakes occurring near the Oregon Coast. Constant displacement rate tests indicated that shear strength decreased exponentially during the first few decimeters of displacement but increased logarithmically with increasing displacement rate when sheared at 0.001 cm s−1 or greater. Dynamic shear resistance estimated from shear strength models correlated well with stresses observed during seismic loading tests, indicating that displacement rate and amount primarily controlled failure characteristics. We developed a stress-based approach to estimate coseismic landslide displacement that utilizes the variable shear strength model. The approach produced results that compared favorably to observations made during seismic loading tests, indicating its utility for application to landslides.

Long‐term Cardiovascular Risks Associated With an Elevated Heart Rate: The Framingham Heart Study

PubMed Central

Ho, Jennifer E.; Larson, Martin G.; Ghorbani, Anahita; Cheng, Susan; Coglianese, Erin E.; Vasan, Ramachandran S.; Wang, Thomas J.

2014-01-01

Background Higher heart rate has been associated with an adverse prognosis, but most prior studies focused on individuals with known cardiovascular disease or examined a limited number of outcomes. We sought to examine the association of baseline heart rate with both fatal and nonfatal outcomes during 2 decades of follow‐up. Methods and Results Our study included 4058 Framingham Heart Study participants (mean age 55 years, 56% women). Cox models were performed with multivariable adjustment for clinical risk factors and physical activity. A total of 708 participants developed incident cardiovascular disease (303 heart failure, 343 coronary heart disease, and 216 stroke events), 48 received a permanent pacemaker, and 1186 died. Baseline heart rate was associated with incident cardiovascular disease (hazard ratio [HR] 1.15 per 1 SD [11 bpm] increase in heart rate, 95% CI 1.07 to 1.24, P=0.0002), particularly heart failure (HR 1.32, 95% CI 1.18 to 1.48, P<0.0001). Higher heart rate was also associated with higher all‐cause (HR 1.17, 95% CI 1.11 to 1.24, P<0.0001) and cardiovascular mortality (HR 1.18, 95% CI 1.04 to 1.33, P=0.01). Spline analyses did not suggest a lower threshold beyond which the benefit of a lower heart rate abated or increased. In contrast, individuals with a higher heart rate had a lower risk of requiring permanent pacemaker placement (HR 0.55, 95% CI 0.38 to 0.79, P=0.001). Conclusions Individuals with a higher heart rate are at elevated long‐term risk for cardiovascular events, in particular, heart failure, and all‐cause death. On the other hand, a higher heart rate is associated with a lower risk of future permanent pacemaker implantation. PMID:24811610

The future of hemodialysis membranes.

PubMed

Humes, H D; Fissell, W H; Tiranathanagul, K

2006-04-01

Hemodialytic treatment of patients with either acute or chronic renal failure has had a dramatic impact on the mortality rates of these patients. Unfortunately, this membrane-based therapy is still incomplete renal replacement, as the mortality and morbidity of these patients remain unacceptably high. Much progress must be made to improve the biocompatibility of hemodialysis membranes as well as their hydraulic and permselective properties to remove small solutes and 'middle molecules' in compact cartridges. The next directions of development will leverage materials and mechanical engineering technology, including microfluidics and nanofabrication, to further improve the clearance functions of the kidney to replicate glomerular permselectivity while retaining high rates of hydraulic permeability. The extension of membrane technology to biohybrid devices utilizing progenitor/stem cells will be another substantive advance for renal replacement therapy. The ability to not only replace solute and water clearance but also active reabsorptive transport and metabolic activity will add additional benefit to the therapy of patients suffering from renal failure. This area of translational research is rich in creative opportunities to improve the unmet medical needs of patients with either chronic or acute renal failure.

Barriers to the implementation of management systems: lessons from the past.

PubMed

Gardner, D

2000-01-01

There is a substantial body of evidence, both empirical and anecdotal, concerning factors associated with the success and failure of management systems. Given the increasing interest in management systems for occupational health and safety, quality, and the environment, it is worth looking at some of these factors in order to learn from them and plan for the future. One of the most comprehensive sources of information about factors that can make a management system succeed or fail lies in the material written about systems that improve the quality of products and services. Such systems were extremely widespread during the 1970s and 1980s but are now much less often cited or studied by Australian organisations. One of the reasons underlying the present relative lack of emphasis is that such programs, both here and overseas, experienced a failure rate of between 85% and 95%. While it may seem unlikely that occupational health and safety (OHS) and environmental management systems will experience similar failure rates, it is still worthwhile to look at what went wrong with other systems and to learn from these experiences.

Analysis of recent failures of disease modifying therapies in Alzheimer's disease suggesting a new methodology for future studies.

PubMed

Amanatkar, Hamid Reza; Papagiannopoulos, Bill; Grossberg, George Thomas

2017-01-01

Pharmaceutical companies and the NIH have invested heavily in a variety of potential disease-modifying therapies for Alzheimer's disease (AD) but unfortunately all double-blind placebo-controlled Phase III studies of these drugs have failed to show statistically significant results supporting their clinical efficacy on cognitive measures. These negative results are surprising as most of these medications have the capability to impact the biomarkers which are associated with progression of Alzheimer's disease. Areas covered: This contradiction prompted us to review all study phases of Intravenous Immunoglobulin (IVIG), Bapineuzumab, Solanezumab, Avagacestat and Dimebolin to shed more light on these recent failures. We critically analyzed these studies, recommending seven lessons from these failures which should not be overlooked. Expert commentary: We suggest a new methodology for future treatment research in Alzheimer's disease considering early intervention with more focus on cognitive decline as a screening tool, more sophisticated exclusion criteria with more reliance on biomarkers, stratification of subjects based on the rate of cognitive decline aiming less heterogeneity, and a longer study duration with periodic assessment of cognition and activities of daily living during the study and also after a washout period.

National audit of the sensitivity of double-contrast barium enema for colorectal carcinoma, using control charts For the Royal College of Radiologists Clinical Radiology Audit Sub-Committee.

PubMed

Tawn, D J; Squire, C J; Mohammed, M A; Adam, E J

2005-05-01

To audit the sensitivity of double-contrast barium enema (DCBE) for colorectal carcinoma, as currently practised in UK departments of radiology. As part of its programme of national audits, the Royal College of Radiologists Clinical Radiology Audit Sub-Committee undertook a retrospective audit of the sensitivity of DCBE for colorectal carcinoma during 2002. The following targets were set: demonstration of a lesion > or =95%; correct identification as a carcinoma > or =90%. Across the UK, 131 departments took part in the audit, involving 5454 examinations. The mean demonstration rate was 92.9% and the diagnosis rate was 85.9%, slightly below the targets set. The equivocal rate (lesion demonstrated, but not defined as malignant) was 6.9%, the perception failure rate was 2.8% and the technical failure rate was 4.4%. Control-chart methodology was used to analyze the data and to identify any departments whose performance was consistent with special-cause variation. When compared with the diagnosis rate (84.6%) and demonstration rate (92.7%) reported in the Wessex Audit 1995, [Thomas RD, Fairhurst JJ, Frost RA. Wessex regional audit: barium enema in colo-rectal carcinoma. Clin Radiol 1995;50:647-50.] a similar level of performance was observed in the NHS today, implying that the basic process for undertaking and reporting DCBE has remained relatively unchanged over the last few years. Improvement in the future will require fundamental changes to the process of reporting DCBE, in order to minimize the perception failure rate and accurately to describe lesions, so reducing the equivocal rate. Control-chart methodology has a useful role in identifying strategies to deliver continual improvement.

Biologic Treatments for Sports Injuries II Think Tank—Current Concepts, Future Research, and Barriers to Advancement, Part 2

PubMed Central

Murray, Iain R.; LaPrade, Robert F.; Musahl, Volker; Geeslin, Andrew G.; Zlotnicki, Jason P.; Mann, Barton J.; Petrigliano, Frank A.

2016-01-01

Rotator cuff tears are common and result in considerable morbidity. Tears within the tendon substance or at its insertion into the humeral head represent a considerable clinical challenge because of the hostile local environment that precludes healing. Tears often progress without intervention, and current surgical treatments are inadequate. Although surgical implants, instrumentation, and techniques have improved, healing rates have not improved, and a high failure rate remains for large and massive rotator cuff tears. The use of biologic adjuvants that contribute to a regenerative microenvironment have great potential for improving healing rates and function after surgery. This article presents a review of current and emerging biologic approaches to augment rotator cuff tendon and muscle regeneration focusing on the scientific rationale, preclinical, and clinical evidence for efficacy, areas for future research, and current barriers to advancement and implementation. PMID:27099865

Heroic Reliability Improvement in Manned Space Systems

NASA Technical Reports Server (NTRS)

Jones, Harry W.

2017-01-01

System reliability can be significantly improved by a strong continued effort to identify and remove all the causes of actual failures. Newly designed systems often have unexpected high failure rates which can be reduced by successive design improvements until the final operational system has an acceptable failure rate. There are many causes of failures and many ways to remove them. New systems may have poor specifications, design errors, or mistaken operations concepts. Correcting unexpected problems as they occur can produce large early gains in reliability. Improved technology in materials, components, and design approaches can increase reliability. The reliability growth is achieved by repeatedly operating the system until it fails, identifying the failure cause, and fixing the problem. The failure rate reduction that can be obtained depends on the number and the failure rates of the correctable failures. Under the strong assumption that the failure causes can be removed, the decline in overall failure rate can be predicted. If a failure occurs at the rate of lambda per unit time, the expected time before the failure occurs and can be corrected is 1/lambda, the Mean Time Before Failure (MTBF). Finding and fixing a less frequent failure with the rate of lambda/2 per unit time requires twice as long, time of 1/(2 lambda). Cutting the failure rate in half requires doubling the test and redesign time and finding and eliminating the failure causes.Reducing the failure rate significantly requires a heroic reliability improvement effort.

Suitability of amphibians and reptiles for translocation.

PubMed

Germano, Jennifer M; Bishop, Phillip J

2009-02-01

Translocations are important tools in the field of conservation. Despite increased use over the last few decades, the appropriateness of translocations for amphibians and reptiles has been debated widely over the past 20 years. To provide a comprehensive evaluation of the suitability of amphibians and reptiles for translocation, we reviewed the results of amphibian and reptile translocation projects published between 1991 and 2006. The success rate of amphibian and reptile translocations reported over this period was twice that reported in an earlier review in 1991. Success and failure rates were independent of the taxonomic class (Amphibia or Reptilia) released. Reptile translocations driven by human-wildlife conflict mitigation had a higher failure rate than those motivated by conservation, and more recent projects of reptile translocations had unknown outcomes. The outcomes of amphibian translocations were significantly related to the number of animals released, with projects releasing over 1000 individuals being most successful. The most common reported causes of translocation failure were homing and migration of introduced individuals out of release sites and poor habitat. The increased success of amphibian and reptile translocations reviewed in this study compared with the 1991 review is encouraging for future conservation projects. Nevertheless, more preparation, monitoring, reporting of results, and experimental testing of techniques and reintroduction questions need to occur to improve translocations of amphibians and reptiles as a whole.

Projected changes in crop yield mean and variability over West Africa in a world 1.5 K warmer than the pre-industrial era

NASA Astrophysics Data System (ADS)

Parkes, Ben; Defrance, Dimitri; Sultan, Benjamin; Ciais, Philippe; Wang, Xuhui

2018-02-01

The ability of a region to feed itself in the upcoming decades is an important issue. The West African population is expected to increase significantly in the next 30 years. The responses of crops to short-term climate change is critical to the population and the decision makers tasked with food security. This leads to three questions: how will crop yields change in the near future? What influence will climate change have on crop failures? Which adaptation methods should be employed to ameliorate undesirable changes? An ensemble of near-term climate projections are used to simulate maize, millet and sorghum in West Africa in the recent historic period (1986-2005) and a near-term future when global temperatures are 1.5 K above pre-industrial levels to assess the change in yield, yield variability and crop failure rate. Four crop models were used to simulate maize, millet and sorghum in West Africa in the historic and future climates. Across the majority of West Africa the maize, millet and sorghum yields are shown to fall. In the regions where yields increase, the variability also increases. This increase in variability increases the likelihood of crop failures, which are defined as yield negative anomalies beyond 1 standard deviation during the historic period. The increasing variability increases the frequency of crop failures across West Africa. The return time of crop failures falls from 8.8, 9.7 and 10.1 years to 5.2, 6.3 and 5.8 years for maize, millet and sorghum respectively. The adoption of heat-resistant cultivars and the use of captured rainwater have been investigated using one crop model as an idealized sensitivity test. The generalized doption of a cultivar resistant to high-temperature stress during flowering is shown to be more beneficial than using rainwater harvesting.

A pilot study on the functional performance and acceptability of an innovative female condom (Wondaleaf®) in Malaysia.

PubMed

Ting, Rachel Sing-Kiat; Wong, Ee-Lynn; Tnay, Jessie Koh-Sing

2018-01-01

Female condom (FC) has been available for over 30 years, but it still lacks wide acceptability. To overcome misdirection and invagination occurring in FC and to provide a wider area of protection, Wondaleaf ® (WL), a new-generation adhesive FC, was recently invented. This pioneering study sought to assess the acceptability and functional performance of WL among Malaysian women. A mixed method survey was conducted in three cities of Malaysia, recruiting sexually active heterosexual women, aged 18-50, by snowball sampling method. Participants were provided with WL and initially surveyed to rate its performance in five coital usages over 2 months. After that, the participants underwent a second survey to rate their satisfaction and acceptability toward WL. Descriptive statistics on clinical failure rates were tabulated with correlational analysis performed to identify major variables contributing to WL's functional performance and acceptability. Out of the 51 enrolled participants, 31 women completed the required surveys. WL's total clinical failure rate was 2.60% (out of 155 condom uses) with above-average ratings of functional performance. The ease of use significantly correlated with ratings of no slippage and no misdirection. The confidence in WL's safety features significantly correlated with a sense of empowerment and protection. WL has a relatively low risk of clinical failures and an overall favorable acceptability among Malaysian women. However, this study also showed that its future usage largely depends on partner acceptability. It may have the potential of complementing the existing barrier toward contraceptive use. Further studies are needed to understand the global acceptability of WL.

Rates of Initial Virological Suppression and Subsequent Virological Failure After Initiating Highly Active Antiretroviral Therapy: The Impact of Aboriginal Ethnicity and Injection Drug Use

PubMed Central

Martin, L.J.; Houston, S.; Yasui, Y.; Wild, T.C.; Saunders, L.D.

2010-01-01

Objectives: To compare rates of initial virological suppression and subsequent virological failure by Aboriginal ethnicity after starting highly active antiretroviral therapy (HAART). Methods: We conducted a retrospective cohort study of antiretroviral-naïve HIV-patients starting HAART in January 1999-June 2005 (baseline), followed until December 31, 2005 in Alberta, Canada. We compared the odds of achieving initial virological suppression (viral load <500 copies/mL) by Aboriginal ethnicity using logistic regression and, among those achieving suppression, rates of virological failure (the first of two consecutive viral loads > 1000 copies/mL) by Aboriginal ethnicity using cumulative incidence curves and Cox proportional hazards models. Sex, injection drug use as an HIV exposure category (IDU), baseline age, CD4 cell count, viral load, calendar year, and HAART regimen were considered as potential confounders. Results: Of 461 study patients, 37% were Aboriginal and 48% were IDUs; 71% achieved initial virological suppression and were followed for 730.4 person-years. After adjusting for confounding variables, compared to non-Aboriginals with other exposures, the odds of achieving initial virological suppression were lower for Aboriginal IDUs (odds ratio (OR)=0.33, 95% CI=0.19-0.60, p=0.0002), non-Aboriginal IDUs (OR=0.30, 95% CI=0.15-0.60, p=0.0006), and Aboriginals with other exposures (OR=0.38, 95% CI=0.21-0.67, p=0.0009). Among those achieving suppression, Aboriginals experienced higher virological failure rates ≥1 year after suppression (hazard ratio=3.35, 95% CI=1.68-6.65, p=0.0006). Conclusions: Future research should investigate adherence among Aboriginals and IDUs treated with HAART and explore their treatment experiences to assess ways to improve outcomes. PMID:21187007

Impact of liver volume and liver function on posthepatectomy liver failure after portal vein embolization- A multivariable cohort analysis.

PubMed

Alizai, Patrick H; Haelsig, Annabel; Bruners, Philipp; Ulmer, Florian; Klink, Christian D; Dejong, Cornelis H C; Neumann, Ulf P; Schmeding, Maximilian

2018-01-01

Liver failure remains a life-threatening complication after liver resection, and is difficult to predict preoperatively. This retrospective cohort study evaluated different preoperative factors in regard to their impact on posthepatectomy liver failure (PHLF) after extended liver resection and previous portal vein embolization (PVE). Patient characteristics, liver function and liver volumes of patients undergoing PVE and subsequent liver resection were analyzed. Liver function was determined by the LiMAx test (enzymatic capacity of cytochrome P450 1A2). Factors associated with the primary end point PHLF (according to ISGLS definition) were identified through multivariable analysis. Secondary end points were 30-day mortality and morbidity. 95 patients received PVE, of which 64 patients underwent major liver resection. PHLF occurred in 7 patients (11%). Calculated postoperative liver function was significantly lower in patients with PHLF than in patients without PHLF (67 vs. 109 μg/kg/h; p = 0.01). Other factors associated with PHLF by univariable analysis were age, future liver remnant, MELD score, ASA score, renal insufficiency and heart insufficiency. By multivariable analysis, future liver remnant was the only factor significantly associated with PHLF (p = 0.03). Mortality and morbidity rates were 4.7% and 29.7% respectively. Future liver remnant is the only preoperative factor with a significant impact on PHLF. Assessment of preoperative liver function may additionally help identify patients at risk for PHLF.

High Speed Dynamics in Brittle Materials

NASA Astrophysics Data System (ADS)

Hiermaier, Stefan

2015-06-01

Brittle Materials under High Speed and Shock loading provide a continuous challenge in experimental physics, analysis and numerical modelling, and consequently for engineering design. The dependence of damage and fracture processes on material-inherent length and time scales, the influence of defects, rate-dependent material properties and inertia effects on different scales make their understanding a true multi-scale problem. In addition, it is not uncommon that materials show a transition from ductile to brittle behavior when the loading rate is increased. A particular case is spallation, a brittle tensile failure induced by the interaction of stress waves leading to a sudden change from compressive to tensile loading states that can be invoked in various materials. This contribution highlights typical phenomena occurring when brittle materials are exposed to high loading rates in applications such as blast and impact on protective structures, or meteorite impact on geological materials. A short review on experimental methods that are used for dynamic characterization of brittle materials will be given. A close interaction of experimental analysis and numerical simulation has turned out to be very helpful in analyzing experimental results. For this purpose, adequate numerical methods are required. Cohesive zone models are one possible method for the analysis of brittle failure as long as some degree of tension is present. Their recent successful application for meso-mechanical simulations of concrete in Hopkinson-type spallation tests provides new insight into the dynamic failure process. Failure under compressive loading is a particular challenge for numerical simulations as it involves crushing of material which in turn influences stress states in other parts of a structure. On a continuum scale, it can be modeled using more or less complex plasticity models combined with failure surfaces, as will be demonstrated for ceramics. Models which take microstructural cracking directly into account may provide a more physics-based approach for compressive failure in the future.

Baccalaureate education in nursing and patient outcomes.

PubMed

Blegen, Mary A; Goode, Colleen J; Park, Shin Hye; Vaughn, Thomas; Spetz, Joanne

2013-02-01

The aim of this study was to examine the effects of registered nurse (RN) education by determining whether nurse-sensitive patient outcomes were better in hospitals with a higher proportion of RNs with baccalaureate degrees. The Future of Nursing report recommends increasing the percentage of RNs with baccalaureate degrees from 50% to 80% by 2020. Research has linked RN education levels to hospital mortality rates but not with other nurse-sensitive outcomes. This was a cross-sectional study that, with the use of data from 21 University HealthSystem Consortium hospitals, analyzed the association between RN education and patient outcomes (risk-adjusted patient safety and quality of care indicators), controlling for nurse staffing and hospital characteristics. Hospitals with a higher percentage of RNs with baccalaureate or higher degrees had lower congestive heart failure mortality, decubitus ulcers, failure to rescue, and postoperative deep vein thrombosis or pulmonary embolism and shorter length of stay. The recommendation of the Future of Nursing report to increase RN education levels is supported by these findings.

Influence of Prior Heart Failure Hospitalization on Cardiovascular Events in Patients with Reduced and Preserved Ejection Fraction

PubMed Central

Bello, Natalie A.; Claggett, Brian; Desai, Akshay S.; McMurray, John J.V.; Granger, Christopher B.; Yusuf, Salim; Swedberg, Karl; Pfeffer, Marc A.; Solomon, Scott D.

2014-01-01

Background Hospitalization for acute heart failure (HF) is associated with high rates of subsequent mortality and readmission. We assessed the influence of the time interval between prior HF hospitalization and randomization in the CHARM trials on clinical outcomes in patients with both reduced and preserved ejection fraction. Methods and Results CHARM enrolled 7,599 patients with NYHA class II-IV heart failure, of whom 5,426 had a history of prior HF hospitalization. Cox proportional hazards regression models were utilized to assess the association between time from prior HF hospitalization and randomization and the primary outcome of cardiovascular death or unplanned admission to hospital for the management of worsening HF over a median of 36.6 months. For patients with HF and reduced (HFrEF) or preserved (HFpEF) ejection fraction, rates of CV mortality and HF hospitalization were higher among patients with prior HF hospitalization than those without. The risk for mortality and hospitalization varied inversely with the time interval between hospitalization and randomization. Rates were higher for HFrEF patients within each category. Event rates for those with HFpEF and a HF hospitalization in the 6 months prior to randomization were comparable to the rate in HFrEF patients with no prior HF hospitalization. Conclusions Rates of CV death or HF hospitalization are greatest in those who have been previously hospitalized for HF. Independent of EF, rates of death and readmission decline as time from HF hospitalization to trial enrollment increased. Recent HF hospitalization identifies a high risk population for future clinical trials in HFrEF and HFpEF. Clinical Trial Registration URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00634400. PMID:24874200

On the use and the performance of software reliability growth models

NASA Technical Reports Server (NTRS)

Keiller, Peter A.; Miller, Douglas R.

1991-01-01

We address the problem of predicting future failures for a piece of software. The number of failures occurring during a finite future time interval is predicted from the number failures observed during an initial period of usage by using software reliability growth models. Two different methods for using the models are considered: straightforward use of individual models, and dynamic selection among models based on goodness-of-fit and quality-of-prediction criteria. Performance is judged by the relative error of the predicted number of failures over future finite time intervals relative to the number of failures eventually observed during the intervals. Six of the former models and eight of the latter are evaluated, based on their performance on twenty data sets. Many open questions remain regarding the use and the performance of software reliability growth models.

High Technology Systems with Low Technology Failures: Some Experiences with Rockets on Software Quality and Integration

NASA Technical Reports Server (NTRS)

Craig, Larry G.

2010-01-01

This slide presentation reviews three failures of software and how the failures contributed to or caused the failure of a launch or payload insertion into orbit. In order to avoid these systematic failures in the future, failure mitigation strategies are suggested for use.

Service Life Extension of the Propulsion System of Long-Term Manned Orbital Stations

NASA Technical Reports Server (NTRS)

Kamath, Ulhas; Kuznetsov, Sergei; Spencer, Victor

2014-01-01

One of the critical non-replaceable systems of a long-term manned orbital station is the propulsion system. Since the propulsion system operates beginning with the launch of station elements into orbit, its service life determines the service life of the station overall. Weighing almost a million pounds, the International Space Station (ISS) is about four times as large as the Russian space station Mir and about five times as large as the U.S. Skylab. Constructed over a span of more than a decade with the help of over 100 space flights, elements and modules of the ISS provide more research space than any spacecraft ever built. Originally envisaged for a service life of fifteen years, this Earth orbiting laboratory has been in orbit since 1998. Some elements that have been launched later in the assembly sequence were not yet built when the first elements were placed in orbit. Hence, some of the early modules that were launched at the inception of the program were already nearing the end of their design life when the ISS was finally ready and operational. To maximize the return on global investments on ISS, it is essential for the valuable research on ISS to continue as long as the station can be sustained safely in orbit. This paper describes the work performed to extend the service life of the ISS propulsion system. A system comprises of many components with varying failure rates. Reliability of a system is the probability that it will perform its intended function under encountered operating conditions, for a specified period of time. As we are interested in finding out how reliable a system would be in the future, reliability expressed as a function of time provides valuable insight. In a hypothetical bathtub shaped failure rate curve, the failure rate, defined as the number of failures per unit time that a currently healthy component will suffer in a given future time interval, decreases during infant-mortality period, stays nearly constant during the service life and increases at the end when the design service life ends and wear-out phase begins. However, the component failure rates do not remain constant over the entire cycle life. The failure rate depends on various factors such as design complexity, current age of the component, operating conditions, severity of environmental stress factors, etc. Development, qualification and acceptance test processes provide rigorous screening of components to weed out imperfections that might otherwise cause infant mortality failures. If sufficient samples are tested to failure, the failure time versus failure quantity can be analyzed statistically to develop a failure probability distribution function (PDF), a statistical model of the probability of failure versus time. Driven by cost and schedule constraints however, spacecraft components are generally not tested in large numbers. Uncertainties in failure rate and remaining life estimates increase when fewer units are tested. To account for this, spacecraft operators prefer to limit useful operations to a period shorter than the maximum demonstrated service life of the weakest component. Running each component to its failure to determine the maximum possible service life of a system can become overly expensive and impractical. Spacecraft operators therefore, specify the required service life and an acceptable factor of safety (FOS). The designers use these requirements to limit the life test duration. Midway through the design life, when benefits justify additional investments, supplementary life test may be performed to demonstrate the capability to safely extend the service life of the system. An innovative approach is required to evaluate the entire system, without having to go through an elaborate test program of propulsion system elements. Evaluating every component through a brute force test program would be a cost prohibitive and time consuming endeavor. ISS propulsion system components were designed and built decades ago. There are no representative ground test articles for some of the components. A 'test everything' approach would require manufacturing new test articles. The paper outlines some of the techniques used for selective testing, by way of cherry picking candidate components based on failure mode effects analysis, system level impacts, hazard analysis, etc. The type of testing required for extending the service life depends on the design and criticality of the component, failure modes and failure mechanisms, life cycle margin provided by the original certification, operational and environmental stresses encountered, etc. When specific failure mechanism being considered and the underlying relationship of that mode to the stresses provided in the test can be correlated by supporting analysis, time and effort required for conducting life extension testing can be significantly reduced. Exposure to corrosive propellants over long periods of time, for instance, lead to specific failure mechanisms in several components used in the propulsion system. Using Arrhenius model, which is tied to chemically dependent failure mechanisms such as corrosion or chemical reactions, it is possible to subject carefully selected test articles to accelerated life test. Arrhenius model reflects the proportional relationship between time to failure of a component and the exponential of the inverse of absolute temperature acting on the component. The acceleration factor is used to perform tests at higher stresses that allow direct correlation between the times to failure at a high test temperature to the temperatures to be expected in actual use. As long as the temperatures are such that new failure mechanisms are not introduced, this becomes a very useful method for testing to failure a relatively small sample of items for a much shorter amount of time. In this article, based on the example of the propulsion system of the first ISS module Zarya, theoretical approaches and practical activities of extending the service life of the propulsion system are reviewed with the goal of determining the maximum duration of its safe operation.

A pilot study on the functional performance and acceptability of an innovative female condom (Wondaleaf®) in Malaysia

PubMed Central

Wong, Ee-Lynn; Tnay, Jessie Koh-Sing

2018-01-01

Background Female condom (FC) has been available for over 30 years, but it still lacks wide acceptability. To overcome misdirection and invagination occurring in FC and to provide a wider area of protection, Wondaleaf® (WL), a new-generation adhesive FC, was recently invented. This pioneering study sought to assess the acceptability and functional performance of WL among Malaysian women. Methods A mixed method survey was conducted in three cities of Malaysia, recruiting sexually active heterosexual women, aged 18–50, by snowball sampling method. Participants were provided with WL and initially surveyed to rate its performance in five coital usages over 2 months. After that, the participants underwent a second survey to rate their satisfaction and acceptability toward WL. Descriptive statistics on clinical failure rates were tabulated with correlational analysis performed to identify major variables contributing to WL’s functional performance and acceptability. Results Out of the 51 enrolled participants, 31 women completed the required surveys. WL’s total clinical failure rate was 2.60% (out of 155 condom uses) with above-average ratings of functional performance. The ease of use significantly correlated with ratings of no slippage and no misdirection. The confidence in WL’s safety features significantly correlated with a sense of empowerment and protection. Conclusion WL has a relatively low risk of clinical failures and an overall favorable acceptability among Malaysian women. However, this study also showed that its future usage largely depends on partner acceptability. It may have the potential of complementing the existing barrier toward contraceptive use. Further studies are needed to understand the global acceptability of WL. PMID:29440937

Power Goals for NASA's Exploration Program

NASA Technical Reports Server (NTRS)

Jeevarajan, Judith A.

2009-01-01

Exciting Future Programs ahead for NASA. Power is needed for all Exploration vehicles and for the missions. For long term missions as in Lunar and Mars programs, safe, high energy/ultra high energy batteries are required. Safety is top priority for human-rated missions. Two-fault tolerance to catastrophic failures is required for human-rated safety To meet power safety goals -inherent cell safety may be required; it can lessen complexity of external protective electronics and prevents dependency on hardware that may also have limitations. Inherent cell safety will eliminate the need to carry out screening of all cells (X-rays, vibration, etc.)

[Diabetic nephropathy: current diagnostics and treatment].

PubMed

Werth, S; Lehnert, H; Steinhoff, J

2015-05-01

Diabetic kidney disease is a leading cause of renal failure in Germany. Albuminuria is an early diagnostic indicator of renal damage in diabetes and, aside from renal failure, a major risk factor of cardiovascular disease. An early diagnosis of diabetic kidney disease is of great importance to reduce associated cardiovascular mortality; glycemic control should aim for HbA1c levels of < 7 %. Guidelines on blood pressure differ, but it should generally be reduced to < 140/90 mmHg; stricter limits should be applied if albuminuria is present. ACE inhibitors (ACE-I) or angiotensin receptor blockers (ARB) should be preferred for blood pressure control. A combination of ACE-Is and ARBs or a renin-inhibitor therapy does not improve cardiovascular outcome, instead it increases the rate of adverse events, e.g., hyperkalemia or renal failure. Lipid control, usually with statins, should be started at an early phase of renal failure. Vitamin D receptor activation and uric acid reduction might play a future role in the treatment of diabetic kidney disease. Pharmacological modification of inflammatory signaling appears to be promising but is not yet of clinical relevance.

Failure rates of mini-implants placed in the infrazygomatic region.

PubMed

Uribe, Flavio; Mehr, Rana; Mathur, Ajay; Janakiraman, Nandakumar; Allareddy, Veerasathpurush

2015-01-01

The purpose of this pilot study was to evaluate the failure rates of mini-implants placed in the infrazygomatic region and to evaluate factors that affect their stability. A retrospective cohort study of 30 consecutive patients (55 mini-implants) who had infrazygomatic mini-implants at a University Clinic were evaluated for failure rates. Patient, mini-implant, orthodontic, surgical, and mini-implant maintenance factors were evaluated by univariate logistic regression models for association to failure rates. A 21.8 % failure rate of mini-implants placed in the infazygomatic region was observed. None of the predictor variables were significantly associated with higher or lower odds for failed implants. Failure rates for infrazygomatic mini-implants were slightly higher than those reported in other maxilla-mandibular osseous locations. No predictor variables were found to be associated to the failure rates.

Failure Analysis at the Kennedy Space Center

NASA Technical Reports Server (NTRS)

Salazar, Victoria L.; Wright, M. Clara

2010-01-01

History has shown that failures occur in every engineering endeavor, and what we learn from those failures contributes to the knowledge base to safely complete future missions. The necessity of failure analysis is at its apex at the end of one aged program and at the beginning of a new and untested program. The information that we gain through failure analysis corrects the deficiencies in the current vehicle to make the next generation of vehicles more efficient and safe. The Failure Analysis and Materials Evaluation Branch in the Materials Science Division at the Kennedy Space Center performs metallurgical, mechanical, electrical, and non-metallic materials failure analyses and accident investigations on both flight hardware and ground support equipment for the Space Shuttle, International Space Station, Constellation, and Launch Services Programs. This paper will explore a variety of failure case studies at the Kennedy Space Center and the lessons learned that can be applied in future programs.

Preoperative Cholangitis and Future Liver Remnant Volume Determine the Risk of Liver Failure in Patients Undergoing Resection for Hilar Cholangiocarcinoma.

PubMed

Ribero, Dario; Zimmitti, Giuseppe; Aloia, Thomas A; Shindoh, Junichi; Fabio, Forchino; Amisano, Marco; Passot, Guillaume; Ferrero, Alessandro; Vauthey, Jean-Nicolas

2016-07-01

The highest mortality rates after liver surgery are reported in patients who undergo resection for hilar cholangiocarcinoma (HCCA). In these patients, postoperative death usually follows the development of hepatic insufficiency. We sought to determine the factors associated with postoperative hepatic insufficiency and death due to liver failure in patients undergoing hepatectomy for HCCA. This study included all consecutive patients who underwent hepatectomy with curative intent for HCCA at 2 centers, from 1996 through 2013. Preoperative clinical and operative data were analyzed to identify independent determinants of hepatic insufficiency and liver failure-related death. The study included 133 patients with right or left major (n = 67) or extended (n = 66) hepatectomy. Preoperative biliary drainage was performed in 98 patients and was complicated by cholangitis in 40 cases. In all these patients, cholangitis was controlled before surgery. Major (Dindo III to IV) postoperative complications occurred in 73 patients (55%), with 29 suffering from hepatic insufficiency. Fifteen patients (11%) died within 90 days after surgery, 10 of them from liver failure. On multivariate analysis, predictors of postoperative hepatic insufficiency (all p < 0.05) were preoperative cholangitis (odds ratio [OR] 3.2), future liver remnant (FLR) volume < 30% (OR 3.5), preoperative total bilirubin level >3 mg/dL (OR 4), and albumin level < 3.5 mg/dL (OR 3.3). Only preoperative cholangitis (OR 7.5, p = 0.016) and FLR volume < 30% (OR 7.2, p = 0.019) predicted postoperative liver failure-related death. Preoperative cholangitis and insufficient FLR volume are major determinants of hepatic insufficiency and postoperative liver failure-related death. Given the association between biliary drainage and cholangitis, the preoperative approach to patients with HCCA should be optimized to minimize the risk of cholangitis. Copyright © 2016 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Biomaterials based strategies for rotator cuff repair.

PubMed

Zhao, Song; Su, Wei; Shah, Vishva; Hobson, Divia; Yildirimer, Lara; Yeung, Kelvin W K; Zhao, Jinzhong; Cui, Wenguo; Zhao, Xin

2017-09-01

Tearing of the rotator cuff commonly occurs as among one of the most frequently experienced tendon disorders. While treatment typically involves surgical repair, failure rates to achieve or sustain healing range from 20 to 90%. The insufficient capacity to recover damaged tendon to heal to the bone, especially at the enthesis, is primarily responsible for the failure rates reported. Various types of biomaterials with special structures have been developed to improve tendon-bone healing and tendon regeneration, and have received considerable attention for replacement, reconstruction, or reinforcement of tendon defects. In this review, we first give a brief introduction of the anatomy of the rotator cuff and then discuss various design strategies to augment rotator cuff repair. Furthermore, we highlight current biomaterials used for repair and their clinical applications as well as the limitations in the literature. We conclude this article with challenges and future directions in designing more advanced biomaterials for augmentation of rotator cuff repair. Copyright © 2017 Elsevier B.V. All rights reserved.

CRYOGENIC UPPER STAGE SYSTEM SAFETY

NASA Technical Reports Server (NTRS)

Smith, R. Kenneth; French, James V.; LaRue, Peter F.; Taylor, James L.; Pollard, Kathy (Technical Monitor)

2005-01-01

NASA s Exploration Initiative will require development of many new systems or systems of systems. One specific example is that safe, affordable, and reliable upper stage systems to place cargo and crew in stable low earth orbit are urgently required. In this paper, we examine the failure history of previous upper stages with liquid oxygen (LOX)/liquid hydrogen (LH2) propulsion systems. Launch data from 1964 until midyear 2005 are analyzed and presented. This data analysis covers upper stage systems from the Ariane, Centaur, H-IIA, Saturn, and Atlas in addition to other vehicles. Upper stage propulsion system elements have the highest impact on reliability. This paper discusses failure occurrence in all aspects of the operational phases (Le., initial burn, coast, restarts, and trends in failure rates over time). In an effort to understand the likelihood of future failures in flight, we present timelines of engine system failures relevant to initial flight histories. Some evidence suggests that propulsion system failures as a result of design problems occur shortly after initial development of the propulsion system; whereas failures because of manufacturing or assembly processing errors may occur during any phase of the system builds process, This paper also explores the detectability of historical failures. Observations from this review are used to ascertain the potential for increased upper stage reliability given investments in integrated system health management. Based on a clear understanding of the failure and success history of previous efforts by multiple space hardware development groups, the paper will investigate potential improvements that can be realized through application of system safety principles.

The effects of heart rate control in chronic heart failure with reduced ejection fraction.

PubMed

Grande, Dario; Iacoviello, Massimo; Aspromonte, Nadia

2018-07-01

Elevated heart rate has been associated with worse prognosis both in the general population and in patients with heart failure. Heart rate is finely modulated by neurohormonal signals and it reflects the balance between the sympathetic and the parasympathetic limbs of the autonomic nervous system. For this reason, elevated heart rate in heart failure has been considered an epiphenomenon of the sympathetic hyperactivation during heart failure. However, experimental and clinical evidence suggests that high heart rate could have a direct pathogenetic role. Consequently, heart rate might act as a pathophysiological mediator of heart failure as well as a marker of adverse outcome. This hypothesis has been supported by the observation that the positive effect of beta-blockade could be linked to the degree of heart rate reduction. In addition, the selective heart rate control with ivabradine has recently been demonstrated to be beneficial in patients with heart failure and left ventricular systolic dysfunction. The objective of this review is to examine the pathophysiological implications of elevated heart rate in chronic heart failure and explore the mechanisms underlying the effects of pharmacological heart rate control.

High-Temperature Graphitization Failure of Primary Superheater Tube

NASA Astrophysics Data System (ADS)

Ghosh, D.; Ray, S.; Roy, H.; Mandal, N.; Shukla, A. K.

2015-12-01

Failure of boiler tubes is the main cause of unit outages of the plant, which further affects the reliability, availability and safety of the unit. So failure analysis of boiler tubes is absolutely essential to predict the root cause of the failure and the steps are taken for future remedial action to prevent the failure in near future. This paper investigates the probable cause/causes of failure of the primary superheater tube in a thermal power plant boiler. Visual inspection, dimensional measurement, chemical analysis, metallographic examination and hardness measurement are conducted as the part of the investigative studies. Apart from these tests, mechanical testing and fractographic analysis are also conducted as supplements. Finally, it is concluded that the superheater tube is failed due to graphitization for prolonged exposure of the tube at higher temperature.

Savannah River Site generic data base development

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

Blanton, C.H.; Eide, S.A.

This report describes the results of a project to improve the generic component failure data base for the Savannah River Site (SRS). A representative list of components and failure modes for SRS risk models was generated by reviewing existing safety analyses and component failure data bases and from suggestions from SRS safety analysts. Then sources of data or failure rate estimates were identified and reviewed for applicability. A major source of information was the Nuclear Computerized Library for Assessing Reactor Reliability, or NUCLARR. This source includes an extensive collection of failure data and failure rate estimates for commercial nuclear powermore » plants. A recent Idaho National Engineering Laboratory report on failure data from the Idaho Chemical Processing Plant was also reviewed. From these and other recent sources, failure data and failure rate estimates were collected for the components and failure modes of interest. This information was aggregated to obtain a recommended generic failure rate distribution (mean and error factor) for each component failure mode.« less

Identifying black swans in NextGen: predicting human performance in off-nominal conditions.

PubMed

Wickens, Christopher D; Hooey, Becky L; Gore, Brian F; Sebok, Angelia; Koenicke, Corey S

2009-10-01

The objective is to validate a computational model of visual attention against empirical data--derived from a meta-analysis--of pilots' failure to notice safety-critical unexpected events. Many aircraft accidents have resulted, in part, because of failure to notice nonsalient unexpected events outside of foveal vision, illustrating the phenomenon of change blindness. A model of visual noticing, N-SEEV (noticing-salience, expectancy, effort, and value), was developed to predict these failures. First, 25 studies that reported objective data on miss rate for unexpected events in high-fidelity cockpit simulations were identified, and their miss rate data pooled across five variables (phase of flight, event expectancy, event location, presence of a head-up display, and presence of a highway-in-the-sky display). Second, the parameters of the N-SEEV model were tailored to mimic these dichotomies. The N-SEEV model output predicted variance in the obtained miss rate (r = .73). The individual miss rates of all six dichotomous conditions were predicted within 14%, and four of these were predicted within 7%. The N-SEEV model, developed on the basis of an independent data set, was able to successfully predict variance in this safety-critical measure of pilot response to abnormal circumstances, as collected from the literature. As new technology and procedures are envisioned for the future airspace, it is important to predict if these may compromise safety in terms of pilots' failing to notice unexpected events. Computational models such as N-SEEV support cost-effective means of making such predictions.

Factors that influence vital rates of Seaside and Saltmarsh sparrows in coastal New Jersey, USA

PubMed Central

Roberts, Samuel G.; Longenecker, Rebecca A.; Etterson, Matthew A.; Ruskin, Katharine J.; Elphick, Chris S.; Olsen, Brian J.; Shriver, W. Gregory

2018-01-01

As saltmarsh habitat continues to disappear, understanding the factors that influence saltmarsh breeding bird population dynamics is an important step for the conservation of these declining species. Using five years (2011 – 2015) of demographic data, we evaluated and compared Seaside (Ammodramus maritimus) and Saltmarsh (A. caudacutus) sparrow apparent adult survival and nest survival at the Edwin B. Forsythe National Wildlife Refuge, New Jersey, USA. We determined the effect of site management history (unditched vs. ditched marsh) on adult and nest survival to aid in prioritizing future management or restoration actions. Seaside Sparrow apparent adult survival (61.6%, 95% CI: 52.5 – 70.0%) averaged >1.5 times greater than Saltmarsh Sparrow apparent adult survival (39.9%, 95% CI: 34.0 – 46.2%). Nest survival and predation and flooding rates did not differ between species, and predation was the primary cause of failure for both species. Apparent adult survival and nest survival did not differ between unditched and ditched marshes for either species, indicating that marsh ditching history may not affect breeding habitat quality for these species. With predation as the primary cause of nest failure for both species in New Jersey, we suggest that future research should focus on identification of predator communities in salt marshes and the potential for implementing predator-control programs to limit population declines. PMID:29479129

Application of implantable hemodynamic monitoring in the management of patients with diastolic heart failure: a subgroup analysis of the COMPASS-HF trial.

PubMed

Zile, Michael R; Bourge, Robert C; Bennett, Tom D; Stevenson, Lynne Warner; Cho, Yong K; Adamson, Philip B; Aaron, Mark F; Aranda, Juan M; Abraham, William T; Smart, Frank W; Kueffer, Fred J

2008-12-01

Nearly half of all patients with chronic heart failure (HF) have a normal ejection fraction (EF), and abnormal diastolic function (ie, diastolic heart failure [DHF]). However, appropriate management of DHF patients remains a difficult and uncertain challenge. The Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (COMPASS-HF) trial was designed to evaluate whether an implantable hemodynamic monitor (IHM) was safe and effective in reducing the number of heart failure-related events (HFRE) in patients with chronic HF. The current study presents data on a prespecified and planned subgroup analysis from the COMPASS-HF trial: 70 patients with an EF > or =50% (ie, DHF). As such, this represents a subgroup analysis of the COMPASS-HF Trial. DHF patients were randomized to IHM-guided care (treatment) vs. standard care (control) for 6 months. All 70 patients received optimal medical therapy, but the hemodynamic information from the IHM was used to guide patient management only in the treatment group. The HFRE rate in DHF patients randomized to treatment was 0.58 events/6 months compared with DHF patients randomized to control, which was 0.73 events/6 months; this represented a 20% nonsignificant reduction in the overall HFRE rate in the treatment group (95% CI = -46, 56, P = .66). There was a 29% nonsignificant reduction in the relative risk of a HF hospitalization in the DHF patients randomized to treatment compared with DHF patients randomized to control (95% CI = -69, 70, P = .43). The IHM was shown to be safe and was associated with a very low system-related and procedure-related complication rate in DHF patients. However, in this subgroup analysis limited to 70 DHF patients, the addition IHM-guided care did not significantly lower the rate of HFR events. The results of this subgroup analysis in DHF patients, for whom there are currently no proven, effective management strategies, will be used to design future studies defining the effects of IHM-guided care in patients with DHF.

Lack of Evidence for Racial Disparity in 30-Day All-Cause Readmission Rate for Older US Veterans Hospitalized with Heart Failure.

PubMed

Kheirbek, Raya Elfadel; Wojtusiak, Janusz; Vlaicu, Sorina O; Alemi, Farrokh

Heart failure is the leading cause for 30-day all-cause readmission. Although racial disparities in health care are well documented, their impact on 30-day all-cause readmission rate is inconclusive. We examined the impact of racial disparity on 30-day readmission for hospitalized patients with heart failure. This is a retrospective secondary data analysis for a large veteran cohort in 130 Veterans Affairs Medical Centers. Propensity scores were used to reduce differences in age, gender, survival days, and comorbidities in index hospitalization among 46 524 whites and 14 124 African Americans (AA). At index hospitalization, AA patients were younger (73.04 vs 67.10 years, t = -54.58, P < .000) and less likely to have myocardial infarcts (8.02% vs 9.80%, t = -6.36, P = .000), peripheral vascular disease (15.25% vs 22.51%, t = -18.68, P = .000), chronic obstructive pulmonary disease (39.59% vs 50.05%, t = -21.89, P < .000), and complicated diabetes (23.42% vs 26.24%, t = -6.73, P = .000). AA patients had lower mortality 30 days post-index hospitalization (3.51% vs 5.69%, t = -10.23, P = .000). In contrast, AA patients were more likely to have renal disease (44.03% vs 38.71%, t = 11.32, P < .000) and HIV/AIDS (1.56% vs 0.20%, t = 19.71, P < .000). The 30-day all-cause readmission rate before adjustments was 17.82% for AA patients versus 18.72% for white patients. There was no difference in the 2 rates after adjustments (18% vs 18%; odds of readmission = 1.002, z = 0.08, P = .937). In a large Department of Veterans Affairs (VA) cohort, white and AA veterans hospitalized for heart failure had similar 30-day all-cause readmission rates after adjustments were made for age, gender, survival days, and comorbidities. However, the 30-day all-cause mortality rate was higher for white patients than for AA patients. Future prospective studies are needed to validate results and test generalizability outside the VA system of care.

Risk factors for heart failure in patients with type 2 diabetes mellitus and stage 4 chronic kidney disease treated with bardoxolone methyl.

PubMed

Chin, Melanie P; Wrolstad, Danielle; Bakris, George L; Chertow, Glenn M; de Zeeuw, Dick; Goldsberry, Angie; Linde, Peter G; McCullough, Peter A; McMurray, John J; Wittes, Janet; Meyer, Colin J

2014-12-01

A phase 3 randomized clinical trial was designed to test whether bardoxolone methyl, a nuclear factor erythroid-2-related factor 2 (Nrf2) activator, slows progression to end-stage renal disease in patients with stage 4 chronic kidney disease and type 2 diabetes mellitus. The trial was terminated because of an increase in heart failure in the bardoxolone methyl group; many of the events were clinically associated with fluid retention. We randomized 2,185 patients with type 2 diabetes mellitus (T2DM) and stage 4 chronic kidney disease (CKD) (estimated glomerular filtration rate 15 to <30 mL min(-1) 1.73 m(-2)) to once-daily bardoxolone methyl (20 mg) or placebo. We used classification and regression tree analysis to identify baseline factors predictive of heart failure or fluid overload events. Elevated baseline B-type natriuretic peptide and previous hospitalization for heart failure were identified as predictors of heart failure events; bardoxolone methyl increased the risk of heart failure by 60% in patients with these risk factors. For patients without these baseline characteristics, the risk for heart failure events among bardoxolone methyl- and placebo-treated patients was similar (2%). The same risk factors were also identified as predictors of fluid overload and appeared to be related to other serious adverse events. Bardoxolone methyl contributed to events related to heart failure and/or fluid overload in a subpopulation of susceptible patients with an increased risk for heart failure at baseline. Careful selection of participants and vigilant monitoring of the study drug will be required in any future trials of bardoxolone methyl to mitigate the risk of heart failure and other serious adverse events. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Treatment of chronic hepatitis C with direct-acting antivirals: The role of resistance

PubMed Central

Jiménez-Pérez, Miguel; González-Grande, Rocío; España Contreras, Pilar; Pinazo Martínez, Isabel; de la Cruz Lombardo, Jesús; Olmedo Martín, Raúl

2016-01-01

The use of direct-acting antivirals (DAAs) to treat chronic hepatitis C has resulted in a significant increase in rates of sustained viral response (around 90%-95%) as compared with the standard treatment of peginterferon/ribavirin. Despite this, however, the rates of therapeutic failure in daily clinical practice range from 10%-15%. Most of these cases are due to the presence of resistant viral variants, resulting from mutations produced by substitutions of amino acids in the viral target protein that reduce viral sensitivity to DAAs, thus limiting the efficacy of these drugs. The high genetic diversity of hepatitis C virus has resulted in the existence of resistance-associated variants (RAVs), sometimes even before starting treatment with DAAs, though generally at low levels. These pre-existing RAVs do not appear to impact on the sustained viral response, whereas those that appear after DAA therapy could well be determinant in virological failure with future treatments. As well as the presence of RAVs, virological failure to treatment with DAAs is generally associated with other factors related with a poor response, such as the degree of fibrosis, the response to previous therapy, the viral load or the viral genotype. Nonetheless, viral breakthrough and relapse can still occur in the absence of detectable RAVs and after the use of highly effective DAAs, so that the true clinical impact of the presence of RAVs in therapeutic failure remains to be determined. PMID:27547001

Diagnosing Recent Failures In Hodoscope Photomultiplier Tube Bases For FNAL E906

NASA Astrophysics Data System (ADS)

Stien, Haley; SeaQuest Collaboration

2017-09-01

The E906/SeaQuest experiment at Fermi National Accelerator Laboratory is researching the nucleon quark sea in order to provide an accurate determination of the quark and anti-quark distributions within the nucleon. By colliding a 120 GeV proton beam with a set of fixed targets and tracking the dimuons that hit the detectors, it is possible to study the quark/anti-quark interaction that produced the unique dimuon through the Drell-Yan process. However, E906 recently began to experience a number of failures in the Hodoscope Photomultiplier Tube bases in the first two detector stations, which are used in the trigger. It was known that the two most likely causes were radiation damage or overheating. Radiation damage was able to be ruled out when it was found that there was no increase in the number of base failures in high rate areas. It was clear that the heat generated on the custom high rate bases caused several components on the daughter cards to slowly overheat until failure. Using thermal imaging and two temperature probes, it was observed that the components on the daughter cards would reach temperatures over 100 degrees Celcius very quickly during our tests. This presentation will discuss the diagnostic process and summarize how this issue will be prevented in the future. Supported by U.S. D.O.E. Medium Energy Nuclear Physics under Grant DE-FG02-03ER41243.

Treatment of chronic hepatitis C with direct-acting antivirals: The role of resistance.

PubMed

Jiménez-Pérez, Miguel; González-Grande, Rocío; España Contreras, Pilar; Pinazo Martínez, Isabel; de la Cruz Lombardo, Jesús; Olmedo Martín, Raúl

2016-08-07

The use of direct-acting antivirals (DAAs) to treat chronic hepatitis C has resulted in a significant increase in rates of sustained viral response (around 90%-95%) as compared with the standard treatment of peginterferon/ribavirin. Despite this, however, the rates of therapeutic failure in daily clinical practice range from 10%-15%. Most of these cases are due to the presence of resistant viral variants, resulting from mutations produced by substitutions of amino acids in the viral target protein that reduce viral sensitivity to DAAs, thus limiting the efficacy of these drugs. The high genetic diversity of hepatitis C virus has resulted in the existence of resistance-associated variants (RAVs), sometimes even before starting treatment with DAAs, though generally at low levels. These pre-existing RAVs do not appear to impact on the sustained viral response, whereas those that appear after DAA therapy could well be determinant in virological failure with future treatments. As well as the presence of RAVs, virological failure to treatment with DAAs is generally associated with other factors related with a poor response, such as the degree of fibrosis, the response to previous therapy, the viral load or the viral genotype. Nonetheless, viral breakthrough and relapse can still occur in the absence of detectable RAVs and after the use of highly effective DAAs, so that the true clinical impact of the presence of RAVs in therapeutic failure remains to be determined.

How galectin-3 changes acute heart failure decision making in the emergency department.

PubMed

Peacock, W Frank

2014-10-01

When considering the appropriate disposition plan in a patient presenting to the emergency department (ED) with acute heart failure (HF), the range of options includes discharge home to intensive care unit (ICU) admission. Unfortunately, there are few objective measures to insure optimal choices, and the currently available science is scant at best. The consequences of a lack of a standardized approach are nowhere more evident than as demonstrated by the worldwide 90-day heart failure rehospitalization rate that exceeds 25%. New strategies to address this important gap in clinical care are sorely needed. The measurement of galectin-3 may represent a new alternative to the historical standard of gestalt-based clinical disposition decisions. Elevated galectin-3 can identify patients at very high risk for short-term adverse outcomes, while low levels identify a population with essentially no 90-day revisits. This prospective objective measure of illness severity may aid in clinical decision making and thus represent a future where rehospitalization after HF is an unusual event.

Methods, apparatus and system for notification of predictable memory failure

DOEpatents

Cher, Chen-Yong; Andrade Costa, Carlos H.; Park, Yoonho; Rosenburg, Bryan S.; Ryu, Kyung D.

2017-01-03

A method for providing notification of a predictable memory failure includes the steps of: obtaining information regarding at least one condition associated with a memory; calculating a memory failure probability as a function of the obtained information; calculating a failure probability threshold; and generating a signal when the memory failure probability exceeds the failure probability threshold, the signal being indicative of a predicted future memory failure.

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

NASA Technical Reports Server (NTRS)

Williams, R. E.; Kruger, R.

1980-01-01

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

Predicting Renal Failure Progression in Chronic Kidney Disease Using Integrated Intelligent Fuzzy Expert System.

PubMed

Norouzi, Jamshid; Yadollahpour, Ali; Mirbagheri, Seyed Ahmad; Mazdeh, Mitra Mahdavi; Hosseini, Seyed Ahmad

2016-01-01

Chronic kidney disease (CKD) is a covert disease. Accurate prediction of CKD progression over time is necessary for reducing its costs and mortality rates. The present study proposes an adaptive neurofuzzy inference system (ANFIS) for predicting the renal failure timeframe of CKD based on real clinical data. This study used 10-year clinical records of newly diagnosed CKD patients. The threshold value of 15 cc/kg/min/1.73 m(2) of glomerular filtration rate (GFR) was used as the marker of renal failure. A Takagi-Sugeno type ANFIS model was used to predict GFR values. Variables of age, sex, weight, underlying diseases, diastolic blood pressure, creatinine, calcium, phosphorus, uric acid, and GFR were initially selected for the predicting model. Weight, diastolic blood pressure, diabetes mellitus as underlying disease, and current GFR(t) showed significant correlation with GFRs and were selected as the inputs of model. The comparisons of the predicted values with the real data showed that the ANFIS model could accurately estimate GFR variations in all sequential periods (Normalized Mean Absolute Error lower than 5%). Despite the high uncertainties of human body and dynamic nature of CKD progression, our model can accurately predict the GFR variations at long future periods.

Cytokine adsorbing columns.

PubMed

Taniguchi, Takumi

2010-01-01

Sepsis induces the activation of complement and the release of inflammatory cytokines such as TNF-alpha and IL-1beta. The inflammatory cytokines and nitric oxide induced by sepsis can decrease systemic vascular resistance, resulting in profound hypotension. The combination of hypotension and microvascular occlusion results in tissue ischemia and ultimately leads to multiple organ failure. Recently, several experimental and clinical studies have reported that treatment for adsorption of cytokines is beneficial during endotoxemia and sepsis. Therefore, the present article discusses cytokine adsorbing columns. These columns, such as CytoSorb, CYT-860-DHP, Lixelle, CTR-001 and MPCF-X, the structures of which vary significantly, have excellent adsorption rates for inflammatory cytokines such as TNF-alpha, IL-1beta, IL-6 and IL8. Many studies have demonstrated that treatment with cytokine adsorbing columns has beneficial effects on the survival rate and inflammatory responses in animal septic models. Moreover, several cases have been reported in which treatment with cytokine adsorbing columns is very effective in hemodynamics and organ failures in critically ill patients. Although further investigations and clinical trials are needed, in the future treatment with cytokine adsorbing columns may play a major role in the treatment of hypercytokinemia such as multiple organ failure and acute respiratory distress syndrome. Copyright 2010 S. Karger AG, Basel.

Trifactorial classification system for osteotome sinus floor elevation based on an observational retrospective analysis of 926 implants followed up to 10 years.

PubMed

French, David; Nadji, Nabil; Liu, Shawn X; Larjava, Hannu

2015-06-01

A novel osteotome trifactorial classification system is proposed for transcrestal osteotome-mediated sinus floor elevation (OSFE) sites that includes residual bone height (RBH), sinus floor anatomy (contour), and multiple versus single sites OSFE (tenting). An analysis of RBH, contour, and tenting was retrospectively applied to a cohort of 926 implants placed using OSFE without added bone graft and followed up to 10 years. RBH was divided into three groups: high (RBH > 6 mm), mid (RBH = 4.1 to 6 mm), and low (RBH = 2 to 4 mm). The sinus "contour" was divided into four groups: flat, concave, angle, and septa. For "tenting", single versus multiple adjacent OSFE sites were compared. The prevalence of flat sinus floors increased as RBH decreased. RBH was a significant predictor of failure with rates as follows: low- RBH = 5.1%, mid-RBH = 1.5%, and high-RBH = 0.4%. Flat sinus floors and single sites as compared to multiple sites had higher observed failure rates but neither achieved statistical significance; however, the power of the study was limited by low numbers of failures. The osteotome trifactorial classification system as proposed can assist planning OSFE cases and may allow better comparison of future OSFE studies.

Prospective memory failures in aviation: effects of cue salience, workload, and individual differences.

PubMed

Van Benthem, Kathleen D; Herdman, Chris M; Tolton, Rani G; LeFevre, Jo-Anne

2015-04-01

Prospective memory allows people to complete intended tasks in the future. Prospective memory failures, such as pilots forgetting to inform pattern traffic of their locations, can have fatal consequences. The present research examined the impact of system factors (memory cue salience and workload) and individual differences (pilot age, cognitive health, and expertise) on prospective memory for communication tasks in the cockpit. Pilots (N = 101) flew a Cessna 172 simulator at a non-towered aerodrome while maintaining communication with traffic and attending to flight parameters. Memory cue salience (the prominence of cues that signal an intended action) and workload were manipulated. Prospective memory was measured as radio call completion rates. Pilots' prospective memory was adversely affected by low-salience cues and high workload. An interaction of cue salience, pilots' age, and cognitive health reflected the effects of system and individual difference factors on prospective memory failures. For example, younger pilots with low levels of cognitive health completed 78% of the radio calls associated with low-salience memory cues, whereas older pilots with low cognitive health scores completed just 61% of similar radio calls. Our findings suggest that technologies designed to signal intended future tasks should target those tasks with inherently low-salience memory cues. In addition, increasing the salience of memory cues is most likely to benefit pilots with lower levels of cognitive health in high-workload conditions.

Effectiveness of a transition plan at discharge of patients hospitalized with heart failure: a before-and-after study.

PubMed

Garnier, Antoine; Rouiller, Nathalie; Gachoud, David; Nachar, Carole; Voirol, Pierre; Griesser, Anne-Claude; Uhlmann, Marc; Waeber, Gérard; Lamy, Olivier

2018-05-14

We evaluated the effectiveness of a multidisciplinary transition plan to reduce early readmission among heart failure patients. We conducted a before-and-after study in a tertiary internal medicine department, comparing 3 years of retrospective data (pre-intervention) and 13 months of prospective data (intervention period). Intervention was the introduction in 2013 of a transition plan performed by a multidisciplinary team. We included all consecutive patients hospitalized with symptomatic heart failure and discharged to home. The outcomes were the fraction of days spent in hospital because of readmission, based on the sum of all days spent in hospital, and the rate of readmission. The same measurements were used for those with potentially avoidable readmissions. Four hundred thirty-one patients were included and compared with 1441 patients in the pre-intervention period. Of the 431 patients, 138 received the transition plan while 293 were non-completers. Neither the fraction of days spent for readmissions nor the rate of readmission decreased during the intervention period. However, non-completers had a higher rate of the fraction of days spent for 30 day readmission (19.2% vs. 16.1%, P = 0.002) and for potentially avoidable readmission (9.8% vs. 13.2%, P = 0.001). The rate of potentially avoidable readmission decreased from 11.3% (before) to 9.9% (non-completers) and 8.7% (completers), reaching the adjusted expected range given by SQLape® (7.7-9.1%). A transition plan, requiring many resources, could decrease potentially avoidable readmission but shows no benefit on overall readmission. Future research should focus on potentially avoidable readmissions and other indicators such as patient satisfaction, adverse drug events, or adherence. © 2018 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

A Critical Evaluation of the Representation of Black Patients With Heart Failure and Preserved Ejection Fraction in Clinical Trials: A Literature Review.

PubMed

Lekavich, Carolyn L; Barksdale, Debra J

2016-01-01

In the United States, heart failure costs $34.4 billion annually and is associated with a mortality rate of 20% within 5 years of diagnosis. Heart failure preserved ejection fraction (HFpEF) accounts for 50% of all hospital admissions for heart failure. Black patients develop HFpEF at a significantly earlier age than do white patients, and the 5-year mortality rate for blacks with HFpEF is 30% to 44% higher compared with white patients. Current trials may not represent black patients proportionately to the general population. The primary aim of this literature review was to critically evaluate the representation of black patients in HFpEF trials and propose solutions for future research. PubMed and CINAHL were queried for peer-reviewed journal articles from 1997 to 2014 using 2 sets of search terms that included HFpEF or preserved left ventricular function and all relevant search terms for black patients. Initially, 182 articles were identified; however, after exclusionary criteria were applied, 22 articles remained. After critical review of each article for relevance, a total of 9 articles remained for the review. For the 9 trials reviewed including a total of 63,065 patients with HFpEF, 10,436 (17%) of the patients were black. Three of the 9 trials included less than 10% black patients, 4 trials included 10% to 20% black patients, and 2 trials included greater than 20% black patients. In 2 studies, the percentage of black patients in the HFpEF trial (13% and 17%) was significantly less than the percentage of black patients in the general regional population (53% and 39%), respectively. Although the mortality rate for black patients with HFpEF is 30% to 45% higher than the rate for white patients, 2 of the 9 studies did not have a representative sample of the general HFpEF population and none of the studies reported the objective of establishing a representative study population.

Sex Differences in Trajectories of Risk After Rehospitalization for Heart Failure, Acute Myocardial Infarction, or Pneumonia.

PubMed

Dreyer, Rachel P; Dharmarajan, Kumar; Hsieh, Angela F; Welsh, John; Qin, Li; Krumholz, Harlan M

2017-05-01

Women have an increased risk of rehospitalization in the immediate postdischarge period; however, few studies have determined how readmission risk dynamically changes on a day-to-day basis over the full year after hospitalization by sex and how these differences compare with the risk for mortality. We identified >3 000 000 hospitalizations of patients with a principal discharge diagnosis of heart failure, acute myocardial infarction, or pneumonia and estimated sex differences in the daily risk of rehospitalization/death 1 year after discharge from a population of Medicare fee-for-service beneficiaries aged 65 years and older. We calculated the (1) time required for adjusted rehospitalization/mortality risks to decline 50% from maximum values after discharge, (2) time required for the adjusted readmission risk to approach plateau periods of minimal day-to-day change, and (3) extent to which adjusted risks are greater among recently hospitalized patients versus Medicare patients. We identified 1 392 289, 530 771, and 1 125 231 hospitalizations for heart failure, acute myocardial infarction, and pneumonia, respectively. The adjusted daily risk of rehospitalization varied by admitting condition (hazard rate ratio for women versus men, 1.10 for acute myocardial infarction; hazard rate ratio, 1.04 for heart failure; and hazard rate ratio, 0.98 for pneumonia). However, for all conditions, the adjusted daily risk of death was higher among men versus women (hazard rate ratio women versus with men, <1). For both sexes, there was a similar timing of peak daily risk, half daily risk, and reaching plateau. Although the association of sex with daily risk of rehospitalization varies across conditions, women are at highest risk after discharge for acute myocardial infarction. Future studies should focus on understanding the determinants of sex differences in rehospitalization risk among conditions. © 2017 American Heart Association, Inc.

Perspectives on advance care planning among patients recently requiring non-invasive ventilation for acute respiratory failure: A qualitative study using thematic analysis.

PubMed

Smith, Tracy A; Disler, Rebecca T; Jenkins, Christine R; Ingham, Jane M; Davidson, Patricia M

2017-06-01

Patients requiring non-invasive ventilation for acute-on-chronic respiratory failure due to chronic obstructive pulmonary disease or heart failure exacerbations may have a poor prognosis underscoring the importance of advance care planning. We aimed to describe attitudes to, and experiences of, discussing the future among patients recently treated with non-invasive ventilation. Qualitative research using thematic analysis. Tertiary teaching hospital. Patients with acute hypercapnic respiratory failure requiring non-invasive ventilation. Individuals recently treated with non-invasive ventilation describe feeling the future is beyond their control and instead controlled by their illness. Participants often recognised their poor prognosis but avoided discussing some difficult topics. The majority preferred not to undergo cardiopulmonary resuscitation but most had not discussed this with healthcare professionals. When participants voiced concerns about their future health to family members, they were met with polarised responses. Some encountered willingness for further discussion, while others met deflection, deterring further conversation. An overarching narrative of 'Looking through my illness to an uncertain but concerning future' unites these themes. This study suggests opportunities and barriers for advance care planning in individuals with chronic disease. Patients' understanding of their prognosis and their attitudes to cardiopulmonary resuscitation suggests an opportunity for advance care planning. Structuring discussions around patients' preferences for care during future exacerbations may foster a sense of control over the future despite illness. The diversity of familial responses to patients' concerns about their future health has implications for advance care planning. These findings have the potential to improve care for patients with respiratory failure and suggest an important ongoing research agenda.

The use of cue familiarity during retrieval failure is affected by past versus future orientation.

PubMed

Cleary, Anne M

2015-01-01

Cue familiarity that is brought on by cue resemblance to memory representations is useful for judging the likelihood of a past occurrence with an item that fails to actually be retrieved from memory. The present study examined the extent to which this type of resemblance-based cue familiarity is used in future-oriented judgments made during retrieval failure. Cue familiarity was manipulated using a previously-established method of creating differing degrees of feature overlap between the cue and studied items in memory, and the primary interest was in how these varying degrees of cue familiarity would influence future-oriented feeling-of-knowing (FOK) judgments given in instances of cued recall failure. The present results suggest that participants do use increases in resemblance-based cue familiarity to infer an increased likelihood of future recognition of an unretrieved target, but not to the extent that they use it to infer an increased likelihood of past experience with an unretrieved target. During retrieval failure, the increase in future-oriented FOK judgments with increasing cue familiarity was significantly less than the increase in past-oriented recognition judgments with increasing cue familiarity.

Lox/Gox related failures during Space Shuttle Main Engine development

NASA Technical Reports Server (NTRS)

Cataldo, C. E.

1981-01-01

Specific rocket engine hardware and test facility system failures are described which were caused by high pressure liquid and/or gaseous oxygen reactions. The failures were encountered during the development and testing of the space shuttle main engine. Failure mechanisms are discussed as well as corrective actions taken to prevent or reduce the potential of future failures.

A retrospective survey of the causes of bracket- and tube-bonding failures.

PubMed

Roelofs, Tom; Merkens, Nico; Roelofs, Jeroen; Bronkhorst, Ewald; Breuning, Hero

2017-01-01

To investigate the causes of bonding failures of orthodontic brackets and tubes and the effect of premedicating for saliva reduction. Premedication with atropine sulfate was administered randomly. Failure rate of brackets and tubes placed in a group of 158 consecutive patients was evaluated after a mean period of 67 weeks after bonding. The failure rate in the group without atropine sulfate premedication was 2.4%. In the group with premedication, the failure rate was 2.7%. The Cox regression analysis of these groups showed that atropine application did not lead to a reduction in bond failures. Statistically significant differences in the hazard ratio were found for the bracket regions and for the dental assistants who prepared for the bonding procedure. Premedication did not lead to fewer bracket failures. The roles of the dental assistant and patient in preventing failures was relevant. A significantly higher failure rate for orthodontic appliances was found in the posterior regions.

A failure diagnosis and impact assessment prototype for Space Station Freedom

NASA Technical Reports Server (NTRS)

Baker, Carolyn G.; Marsh, Christopher A.

1991-01-01

NASA is investigating the use of advanced automation to enhance crew productivity for Space Station Freedom in numerous areas, one being failure management. A prototype is described that diagnoses failure sources and assesses the future impacts of those failures on other Freedom entities.

Impact of hyperkalaemia definition on incidence assessment: implications for epidemiological research based on a large cohort study in newly diagnosed heart failure patients in primary care.

PubMed

Martín-Pérez, Mar; Ruigómez, Ana; Michel, Alexander; García Rodríguez, Luis A

2016-05-04

Various definitions of hyperkalaemia have been used in clinical research, and data from routine clinical practice on its incidence are sparse. We aimed to establish the incidence of hyperkalaemia in patients with newly diagnosed heart failure in the UK general population using different definitions for the condition. We conducted a large retrospective cohort study using data from The Health Improvement Network primary care database. Patients with newly diagnosed heart failure (N = 19,194) were identified and followed until the first occurrence of hyperkalaemia. Different serum potassium (K(+)) thresholds were evaluated as possible definitions for hyperkalaemia, and incidence rates (IRs) calculated using a final operational definition both overall and among patient sub-groups. IRs of hyperkalaemia ranged from 0.92-7.93 per 100 person-years according to the definition. Based on considerable differences in the serum K(+) normal range used between practices, 2176 (11.3 %) individuals were identified with a record of hyperkalaemia using our operational definition of a proportional increase of ≥10 % above the upper bound of the normal range: IR 2.90 per 100 person-years (95 % CI 2.78-3.02) over a mean follow-up of 3.91 years. Incidence rates were higher in older patients, and in those with diabetes or renal impairment. Hyperkalaemia is a common finding in heart failure patients in primary care, but its incidence can vary nearly ten-fold depending on its definition. Since assessment of hyperkalaemia risk is essential for therapeutic decision making in heart failure patients, this finding warrants consideration in future epidemiological studies.

Effectiveness and predictors of failure of noninvasive mechanical ventilation in acute respiratory failure.

PubMed

Martín-González, F; González-Robledo, J; Sánchez-Hernández, F; Moreno-García, M N; Barreda-Mellado, I

2016-01-01

To assess the effectiveness and identify predictors of failure of noninvasive ventilation. A retrospective, longitudinal descriptive study was made. Adult patients with acute respiratory failure. A total of 410 consecutive patients with noninvasive ventilation treated in an Intensive Care Unit of a tertiary university hospital from 2006 to 2011. Noninvasive ventilation. Demographic variables and clinical and laboratory test parameters at the start and two hours after the start of noninvasive ventilation. Evolution during admission to the Unit and until hospital discharge. The failure rate was 50%, with an overall mortality rate of 33%. A total of 156 patients had hypoxemic respiratory failure, 87 postextubation respiratory failure, 78 exacerbation of chronic obstructive pulmonary disease, 61 hypercapnic respiratory failure without chronic obstructive pulmonary disease, and 28 had acute pulmonary edema. The failure rates were 74%, 54%, 27%, 31% and 21%, respectively. The etiology of respiratory failure, serum bilirubin at the start, APACHEII score, radiological findings, the need for sedation to tolerate noninvasive ventilation, changes in level of consciousness, PaO2/FIO2 ratio, respiratory rate and heart rate from the start and two hours after the start of noninvasive ventilation were independently associated to failure. The effectiveness of noninvasive ventilation varies according to the etiology of respiratory failure. Its use in hypoxemic respiratory failure and postextubation respiratory failure should be assessed individually. Predictors of failure could be useful to prevent delayed intubation. Copyright © 2015 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Developing Creative and Critical Thinkers

DTIC Science & Technology

2009-12-01

competitive advantage and long-term success. Strategic thinking meshes anticipated requirements with future organizational capabilities to ensure the organization wins in the future. Examples of failures in strategic thinking abound. They include the recent failures of U.S. auto companies to understand the key factors facing their industry. Of greater significance is our own failure of strategic thinking in the formulation and acceptance of the many pre-war assumptions about Iraq. The core elements of strategic thinking are the ability to think creatively and critically

"Proprietary Processed" Allografts: Clinical Outcomes and Biomechanical Properties in Anterior Cruciate Ligament Reconstruction.

PubMed

Roberson, Troy A; Abildgaard, Jeffrey T; Wyland, Douglas J; Siffri, Paul C; Geary, Stephen P; Hawkins, Richard J; Tokish, John M

2017-11-01

The processing of allograft tissues in anterior cruciate ligament (ACL) reconstruction continues to be controversial. While high-dose irradiation of grafts has received scrutiny for high failure rates, lower dose irradiation and "proprietary-based" nonirradiated sterilization techniques have become increasingly popular, with little in the literature to evaluate their outcomes. Recent studies have suggested that the specifics of allograft processing techniques may be a risk factor for higher failure rates. To assess these proprietary processes and their clinical outcomes and biomechanical properties. Systematic review. A systematic review was performed using searches of PubMed, EMBASE, Google Scholar, and Cochrane databases. English-language studies were identified with the following search terms: "allograft ACL reconstruction" (title/abstract), "novel allograft processing" (title/abstract), "allograft anterior cruciate ligament" (title/abstract), "anterior cruciate ligament allograft processing" (title/abstract), or "biomechanical properties anterior cruciate ligament allograft" (title/abstract). Duplicate studies, studies not providing the allograft processing technique, and those not containing the outcomes of interest were excluded. Outcomes of interest included outcome scores, complication and failure rates, and biomechanical properties of the processed allografts. Twenty-four studies (13 clinical, 11 biomechanical) met inclusion criteria for review. No demonstrable difference in patient-reported outcomes was appreciated between the processing techniques, with the exception of the Tutoplast process. The clinical failure rate of the Tutoplast process was unacceptably high (45% at 6 years), but no other difference was found between other processing techniques (BioCleanse: 5.4%; AlloTrue: 5.7%; MTF: 6.7%). Several studies did show an increased failure rate, but these studies either combined processing techniques or failed to delineate enough detail to allow a specific comparison for this study. The biomechanical studies showed overall maintenance of satisfactory biomechanical properties throughout multiple testing modes with normalization to the percentage of control specimens. A comparison of proprietary allograft processing techniques is difficult because of the variability and lack of specificity of reporting in the current literature. Among the available literature, except for the Tutoplast process, no notable differences were found in the clinical outcomes or biomechanical properties. Future study with a longer follow-up is necessary to determine the role and limitations of these grafts in the clinical setting.

Treatment Failure With Rhythm and Rate Control Strategies in Patients With Atrial Fibrillation and Congestive Heart Failure: An AF-CHF Substudy.

PubMed

Dyrda, Katia; Roy, Denis; Leduc, Hugues; Talajic, Mario; Stevenson, Lynne Warner; Guerra, Peter G; Andrade, Jason; Dubuc, Marc; Macle, Laurent; Thibault, Bernard; Rivard, Lena; Khairy, Paul

2015-12-01

Rate and rhythm control strategies for atrial fibrillation (AF) are not always effective or well tolerated in patients with congestive heart failure (CHF). We assessed reasons for treatment failure, associated characteristics, and effects on survival. A total of 1,376 patients enrolled in the AF-CHF trial were followed for 37  ±  19 months, 206 (15.0%) of whom failed initial therapy leading to crossover. Rhythm control was abandoned more frequently than rate control (21.0% vs. 9.1%, P < 0.0001). Crossovers from rhythm to rate control were driven by inefficacy, whereas worsening heart failure was the most common reason to crossover from rate to rhythm control. In multivariate analyses, failure of rhythm control was associated with female sex, higher serum creatinine, functional class III or IV symptoms, lack of digoxin, and oral anticoagulation. Factors independently associated with failure of rate control were paroxysmal (vs. persistent) AF, statin therapy, and presence of an implantable cardioverter-defibrillator. Crossovers were not associated with cardiovascular mortality (hazard ratio [HR] 1.11 from rhythm to rate control; 95% confidence interval [95% CI, 0.73-1.73]; P = 0.6069; HR 1.29 from rate to rhythm control; 95% CI, 0.73-2.25; P = 0.3793) or all-cause mortality (HR 1.16 from rhythm to rate control, 95% CI [0.79-1.72], P = 0.4444; HR 1.15 from rate to rhythm control, 95% [0.69, 1.91], P = 0.5873). Rhythm control is abandoned more frequently than rate control in patients with AF and CHF. The most common reasons for treatment failure are inefficacy for rhythm control and worsening heart failure for rate control. Changing strategies does not impact survival. © 2015 Wiley Periodicals, Inc.

Gait termination in individuals with multiple sclerosis.

PubMed

Roeing, Kathleen L; Wajda, Douglas A; Motl, Robert W; Sosnoff, Jacob J

2015-09-01

Despite the ubiquitous nature of gait impairment in multiple sclerosis (MS), there is limited information concerning the control of gait termination in individuals with MS. The purpose of this investigation was to examine planned gait termination in individuals with MS and healthy controls with and without cognitive distractors. Individuals with MS and age matched controls completed a series of gait termination tasks over a pressure sensitive walkway under non-distracting and cognitively distracting conditions. As expected the MS group had a lower velocity (89.9±33.3 cm/s) than controls (142.8±22.4 cm/s) and there was a significant reduction in velocity in both groups under the cognitive distracting conditions (MS: 73.9±30.7 cm/s; control: 120.0±25.9 cm/s). Although individuals with MS walked slower, there was no difference between groups in the rate a participant failed to stop at the target (i.e. failure rate). Overall failure rate had a 10-fold increase in the cognitively distracting condition across groups. Individuals with MS were more unstable during termination. Future research examining the neuromuscular mechanisms contributing to gait termination is warranted. Copyright © 2015 Elsevier B.V. All rights reserved.

Acute Liver Failure: Summary of a Workshop

PubMed Central

Lee, William M.; Squires, Robert H.; Nyberg, Scott L.; Doo, Edward; Hoofnagle, Jay H.

2011-01-01

Acute liver failure (ALF) is a rare but challenging clinical syndrome with multiple causes; a specific etiology cannot be identified in 15% of adult and 50% of pediatric cases. The course of ALF is variable and the mortality rate is high. Liver transplantation is the only therapy of proven benefit, but the rapidity of progression and the variable course of ALF limit its use. Currently in the United States, spontaneous survival occurs in approximately 45%, liver transplantation in 25%, and death without transplantation in 30% of adults with ALF. Higher rates of spontaneous recovery (56%) and transplantation (31%) with lower rates of death (13%) occur in children. The outcome of ALF varies by etiology, favorable prognoses being found with acetaminophen overdose, hepatitis A, and ischemia (≈60% spontaneous survival), and poor prognoses with drug-induced ALF, hepatitis B, and indeterminate cases (≈25% spontaneous survival). Excellent intensive care is critical in management of patients with ALF. Nonspecific therapies are of unproven benefit. Future possible therapeutic approaches include N-acetylcysteine, hypothermia, liver assist devices, and hepatocyte transplantation. Advances in stem cell research may allow provision of cells for bioartificial liver support. ALF presents many challenging opportunities in both clinical and basic research. PMID:18318440

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. © 2015 Society for Public Health Education.

Reliability analysis of C-130 turboprop engine components using artificial neural network

NASA Astrophysics Data System (ADS)

Qattan, Nizar A.

In this study, we predict the failure rate of Lockheed C-130 Engine Turbine. More than thirty years of local operational field data were used for failure rate prediction and validation. The Weibull regression model and the Artificial Neural Network model including (feed-forward back-propagation, radial basis neural network, and multilayer perceptron neural network model); will be utilized to perform this study. For this purpose, the thesis will be divided into five major parts. First part deals with Weibull regression model to predict the turbine general failure rate, and the rate of failures that require overhaul maintenance. The second part will cover the Artificial Neural Network (ANN) model utilizing the feed-forward back-propagation algorithm as a learning rule. The MATLAB package will be used in order to build and design a code to simulate the given data, the inputs to the neural network are the independent variables, the output is the general failure rate of the turbine, and the failures which required overhaul maintenance. In the third part we predict the general failure rate of the turbine and the failures which require overhaul maintenance, using radial basis neural network model on MATLAB tool box. In the fourth part we compare the predictions of the feed-forward back-propagation model, with that of Weibull regression model, and radial basis neural network model. The results show that the failure rate predicted by the feed-forward back-propagation artificial neural network model is closer in agreement with radial basis neural network model compared with the actual field-data, than the failure rate predicted by the Weibull model. By the end of the study, we forecast the general failure rate of the Lockheed C-130 Engine Turbine, the failures which required overhaul maintenance and six categorical failures using multilayer perceptron neural network (MLP) model on DTREG commercial software. The results also give an insight into the reliability of the engine turbine under actual operating conditions, which can be used by aircraft operators for assessing system and component failures and customizing the maintenance programs recommended by the manufacturer.

Contraceptive failure rates: new estimates from the 1995 National Survey of Family Growth.

PubMed

Fu, H; Darroch, J E; Haas, T; Ranjit, N

1999-01-01

Unintended pregnancy remains a major public health concern in the United States. Information on pregnancy rates among contraceptive users is needed to guide medical professionals' recommendations and individuals' choices of contraceptive methods. Data were taken from the 1995 National Survey of Family Growth (NSFG) and the 1994-1995 Abortion Patient Survey (APS). Hazards models were used to estimate method-specific contraceptive failure rates during the first six months and during the first year of contraceptive use for all U.S. women. In addition, rates were corrected to take into account the underreporting of induced abortion in the NSFG. Corrected 12-month failure rates were also estimated for subgroups of women by age, union status, poverty level, race or ethnicity, and religion. When contraceptive methods are ranked by effectiveness over the first 12 months of use (corrected for abortion underreporting), the implant and injectables have the lowest failure rates (2-3%), followed by the pill (8%), the diaphragm and the cervical cap (12%), the male condom (14%), periodic abstinence (21%), withdrawal (24%) and spermicides (26%). In general, failure rates are highest among cohabiting and other unmarried women, among those with an annual family income below 200% of the federal poverty level, among black and Hispanic women, among adolescents and among women in their 20s. For example, adolescent women who are not married but are cohabiting experience a failure rate of about 31% in the first year of contraceptive use, while the 12-month failure rate among married women aged 30 and older is only 7%. Black women have a contraceptive failure rate of about 19%, and this rate does not vary by family income; in contrast, overall 12-month rates are lower among Hispanic women (15%) and white women (10%), but vary by income, with poorer women having substantially greater failure rates than more affluent women. Levels of contraceptive failure vary widely by method, as well as by personal and background characteristics. Income's strong influence on contraceptive failure suggests that access barriers and the general disadvantage associated with poverty seriously impede effective contraceptive practice in the United States.

Heart rate and outcomes in patients with heart failure with preserved ejection fraction: A dose-response meta-analysis.

PubMed

Shang, Xiaoke; Lu, Rong; Liu, Mei; Xiao, Shuna; Dong, Nianguo

2017-10-01

Although elevated resting heart rate is related to poor outcomes in heart failure (HF) with reduced ejection fraction, the association in HF with preserved ejection fraction (HFpEF) remains inconclusive. Therefore, we conducted a dose-response meta-analysis to examine the prognostic role of heart rate in patients with HFpEF.We searched PubMed and Embase databases until April 2017 and manually reviewed the reference lists of relevant literatures. Random effect models were used to pool the study-specific hazard ratio (HR) of outcomes, including all-cause death, cardiovascular death, and HF hospitalization.Six studies with 7 reports were finally included, totaling 14,054 patients with HFpEF. The summary HR (95% confidence interval [CI]) for every 10 beats/minute increment in heart rate was 1.04 (1.02-1.06) for all-cause death, 1.06 (1.02-1.10) for cardiovascular death, and 1.05 (1.01-1.08) for HF hospitalization. Subgroup analyses indicated that these positive relationships were significant in patients with sinus rhythm but not in those with atrial fibrillation. There was also evidence for nonlinear relationship of heart rate with each of the outcomes (All P for nonlinearity < .05).Higher heart rate in sinus rhythm is a risk factor for adverse outcomes in patients with HFpEF. Future trials are required to determine whether heart rate reduction may improve the prognosis of HFpEF.

Factors affecting failure to quit smoking after exposure to pictorial cigarette pack warnings among employees in Thailand.

PubMed

Sujirarat, Dusit; Silpasuwan, Pimpan; Viwatwongkasem, Chukiat; Sirichothiratana, Nithat

2011-07-01

This study was carried out to determine whether health warning pictures(HWP) affect smoking cessation using a structured equation model for intending-to-quit smokers in work places. Data from a 1-year longitudinal followup of attempt-to-quit employees was obtained to determine if pack warnings affect tobacco cessation rates. Stratified simple random sampling, and Structured Equation Modeling (SEM) were employed. Approximately 20% of intending-to-quit smokers were successful. The integrated model, combining internal, interpersonal factors and health warning pictures as external factors, fit the fail to quit pattern of the model. Having a smoking father was the most significant proximate indicator linked with failure to quit. Although HWL pictures were an external factor in the decision to stop smoking, the direct and indirect causes of failure to quit smoking were the influence of the family members. Fathers contributed to the success or failure of smoking cessation in their children by having an influence on the decision making process. Future HWP should include information about factors that stimulate smokers to quit successfully. The role model of a father on quitting is also important.

Natriuretic peptides and their therapeutic potential in heart failure treatment: An updated review.

PubMed

Namdari, M; Eatemadi, A; Negahdari, B

2016-09-30

Brain natriuretic peptide (BNP), also known as a B-type natriuretic peptide, is one of the important biomarkers with a proven role in the diagnosis of congestive heart failure (CHF). Researchers from the different clinical field have researched into the performance features of BNP testing in the acute care set-up to assist and improve in diagnosing CHF and in predicting future morbidity and mortality rates. The potency of BNP has also been researched into in cases like myocardial ischemia and infarction, cor pulmonale, and acute pulmonary embolism (PE). Based on their vaso-dilatory and diuretic properties and ability to inhibit renin-angiotensin-aldosterone system, natriuretic peptides are able to provide an efficient technique and mechanism of action in the pathophysiologic framework for CHF treatment and management. Recent clinical studies reported that ularitide, a synthetic form of urodilatin, secreted by kidney may be effective in managing and treatment of decompensated heart failure. It has also been reported that Nesiritide, a recombinant natriuretic peptide has been proven to improve dyspnea and hemodynamic parameters in heart failure patients. This review provides an update on natriuretic peptides and their therapeutic potential in CHF treatment.

Megacity megaquakes—Two near misses

USGS Publications Warehouse

Stein, Ross S.; Toda, Shinji

2013-01-01

Two recent earthquakes left their mark on Santiago de Chile and Tokyo, well beyond the rupture zones, raising questions about the future vulnerability of these and other cities that lie in seismically active regions. Though spared strong shaking, the megacities nevertheless lit up in small quakes, perhaps signaling an abrupt change in the condition for failure on the faults beneath the cities. To detect such changes in earthquake rate requires good seismic monitoring networks; to respond to such hazard increases with civic preparations requires good government.

Comparison of Sprint Fidelis and Riata defibrillator lead failure rates.

PubMed

Fazal, Iftikhar A; Shepherd, Ewen J; Tynan, Margaret; Plummer, Christopher J; McComb, Janet M

2013-09-30

Sprint Fidelis and Riata defibrillator leads are prone to early failure. Few data exist on the comparative failure rates and mortality related to lead failure. The aims of this study were to determine the failure rate of Sprint Fidelis and Riata leads, and to compare failure rates and mortality rates in both groups. Patients implanted with Sprint Fidelis leads and Riata leads at a single centre were identified and in July 2012, records were reviewed to ascertain lead failures, deaths, and relationship to device/lead problems. 113 patients had Sprint Fidelis leads implanted between June 2005 and September 2007; Riata leads were implanted in 106 patients between January 2003 and February 2008. During 53.0 ± 22.3 months of follow-up there were 13 Sprint Fidelis lead failures (11.5%, 2.60% per year) and 25 deaths. Mean time to failure was 45.1 ± 15.5 months. In the Riata lead cohort there were 32 deaths, and 13 lead failures (11.3%, 2.71% per year) over 54.8 ± 26.3 months follow-up with a mean time to failure of 53.5 ± 24.5 months. There were no significant differences in the lead failure-free Kaplan-Meier survival curve (p=0.77), deaths overall (p=0.17), or deaths categorised as sudden/cause unknown (p=0.54). Sprint Fidelis and Riata leads have a significant but comparable failure rate at 2.60% per year and 2.71% per year of follow-up respectively. The number of deaths in both groups is similar and no deaths have been identified as being related to lead failure in either cohort. Copyright © 2012. Published by Elsevier Ireland Ltd.

Comparison of Damage Path Predictions for Composite Laminates by Explicit and Standard Finite Element Analysis Tools

NASA Technical Reports Server (NTRS)

Bogert, Philip B.; Satyanarayana, Arunkumar; Chunchu, Prasad B.

2006-01-01

Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. This progressive failure methodology has been implemented in the Abaqus/Explicit and Abaqus/Standard finite element codes through user written subroutines "VUMAT" and "USDFLD" respectively. A 2-D finite element model is used for predicting the intra-laminar damages. Analysis results obtained from the Abaqus/Explicit and Abaqus/Standard code show good agreement with experimental results. The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it.

Prosody and Semantics Are Separate but Not Separable Channels in the Perception of Emotional Speech: Test for Rating of Emotions in Speech.

PubMed

Ben-David, Boaz M; Multani, Namita; Shakuf, Vered; Rudzicz, Frank; van Lieshout, Pascal H H M

2016-02-01

Our aim is to explore the complex interplay of prosody (tone of speech) and semantics (verbal content) in the perception of discrete emotions in speech. We implement a novel tool, the Test for Rating of Emotions in Speech. Eighty native English speakers were presented with spoken sentences made of different combinations of 5 discrete emotions (anger, fear, happiness, sadness, and neutral) presented in prosody and semantics. Listeners were asked to rate the sentence as a whole, integrating both speech channels, or to focus on one channel only (prosody or semantics). We observed supremacy of congruency, failure of selective attention, and prosodic dominance. Supremacy of congruency means that a sentence that presents the same emotion in both speech channels was rated highest; failure of selective attention means that listeners were unable to selectively attend to one channel when instructed; and prosodic dominance means that prosodic information plays a larger role than semantics in processing emotional speech. Emotional prosody and semantics are separate but not separable channels, and it is difficult to perceive one without the influence of the other. Our findings indicate that the Test for Rating of Emotions in Speech can reveal specific aspects in the processing of emotional speech and may in the future prove useful for understanding emotion-processing deficits in individuals with pathologies.

Reliability Growth in Space Life Support Systems

NASA Technical Reports Server (NTRS)

Jones, Harry W.

2014-01-01

A hardware system's failure rate often increases over time due to wear and aging, but not always. Some systems instead show reliability growth, a decreasing failure rate with time, due to effective failure analysis and remedial hardware upgrades. Reliability grows when failure causes are removed by improved design. A mathematical reliability growth model allows the reliability growth rate to be computed from the failure data. The space shuttle was extensively maintained, refurbished, and upgraded after each flight and it experienced significant reliability growth during its operational life. In contrast, the International Space Station (ISS) is much more difficult to maintain and upgrade and its failure rate has been constant over time. The ISS Carbon Dioxide Removal Assembly (CDRA) reliability has slightly decreased. Failures on ISS and with the ISS CDRA continue to be a challenge.

Evaluation of possible prognostic factors for the success, survival, and failure of dental implants.

PubMed

Geckili, Onur; Bilhan, Hakan; Geckili, Esma; Cilingir, Altug; Mumcu, Emre; Bural, Canan

2014-02-01

To analyze the prognostic factors that are associated with the success, survival, and failure rates of dental implants. Data including implant sizes, insertion time, implant location, and prosthetic treatment of 1656 implants have been collected, and the association of these factors with success, survival, and failure of implants was analyzed. The success rate was lower for short and maxillary implants. The failure rate of maxillary implants exceeded that of mandibular implants, and the failure rate of implants that were placed in the maxillary anterior region was significantly higher than other regions. The failure rates of implants that were placed 5 years ago or more were higher than those that were placed later. Anterior maxilla is more critical for implant loss than other sites. Implants in the anterior mandible show better success compared with other locations, and longer implants show better success rates. The learning curve of the clinician influences survival and success rates of dental implants.

Failure rate and reliability of the KOMATSU hydraulic excavator in surface limestone mine

NASA Astrophysics Data System (ADS)

Harish Kumar N., S.; Choudhary, R. P.; Murthy, Ch. S. N.

2018-04-01

The model with failure rate function of bathtub-shaped is helpful in reliability analysis of any system and particularly in reliability associated privative maintenance. The usual Weibull distribution is, however, not capable to model the complete lifecycle of the any with a bathtub-shaped failure rate function. In this paper, failure rate and reliability analysis of the KOMATSU hydraulic excavator/shovel in surface mine is presented and also to improve the reliability and decrease the failure rate of each subsystem of the shovel based on the preventive maintenance. The model of the bathtub-shaped for shovel can also be seen as a simplification of the Weibull distribution.

Levelized cost-benefit analysis of proposed diagnostics for the Ammunition Transfer Arm of the US Army`s Future Armored Resupply Vehicle

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

Wilkinson, V.K.; Young, J.M.

1995-07-01

The US Army`s Project Manager, Advanced Field Artillery System/Future Armored Resupply Vehicle (PM-AFAS/FARV) is sponsoring the development of technologies that can be applied to the resupply vehicle for the Advanced Field Artillery System. The Engineering Technology Division of the Oak Ridge National Laboratory has proposed adding diagnostics/prognostics systems to four components of the Ammunition Transfer Arm of this vehicle, and a cost-benefit analysis was performed on the diagnostics/prognostics to show the potential savings that may be gained by incorporating these systems onto the vehicle. Possible savings could be in the form of reduced downtime, less unexpected or unnecessary maintenance, fewermore » regular maintenance checks. and/or tower collateral damage or loss. The diagnostics/prognostics systems are used to (1) help determine component problems, (2) determine the condition of the components, and (3) estimate the remaining life of the monitored components. The four components on the arm that are targeted for diagnostics/prognostics are (1) the electromechanical brakes, (2) the linear actuators, (3) the wheel/roller bearings, and (4) the conveyor drive system. These would be monitored using electrical signature analysis, vibration analysis, or a combination of both. Annual failure rates for the four components were obtained along with specifications for vehicle costs, crews, number of missions, etc. Accident scenarios based on component failures were postulated, and event trees for these scenarios were constructed to estimate the annual loss of the resupply vehicle, crew, arm. or mission aborts. A levelized cost-benefit analysis was then performed to examine the costs of such failures, both with and without some level of failure reduction due to the diagnostics/prognostics systems. Any savings resulting from using diagnostics/prognostics were calculated.« less

Attributions to Failure: The Effects of Effort, Ability, and Learning Strategy Use on Perceptions of Future Goals and Emotional Responses.

ERIC Educational Resources Information Center

Holschuh, Jodi Patrick; Nist, Sherrie L.; Olejnik, Stephen

2001-01-01

Examines college students' attributions to failure in an introductory biology course. Determines how males and females viewed the attributions of ability, effort, and learning strategy use. Concludes that collectively, results indicate differences in patterns of responses between future goal and emotional items. Notes the importance for…

VLSI (Very Large Scale Integrated Circuits) Device Reliability Models.

DTIC Science & Technology

1984-12-01

CIRCUIT COMPLEXITY FAILURE RATES FOR... A- 40 MOS SSI/MSI DEVICES IN FAILURE PER 106 HOURS TABLE 5.1.2.5-19: C1 AND C2 CIRCUIT COMPLEXITY FAILURE RATES FOR...A- 40 MOS SSI/MSI DEVICES IN FAILURE PER 106 HOURS TABLE 5.1.2.5-19: Cl AND C2 CIRCUIT COMPLEXITY FAILURE RATES FOR... A-41 LINEAR DEVICES IN...19 National Semiconductor 20 Nitron 21 Raytheon 22 Sprague 23 Synertek 24 Teledyne Crystalonics 25 TRW Semiconductor 26 Zilog The following companies

Failure Analysis and Mechanisms of Failure of Fibrous Composite Structures

NASA Technical Reports Server (NTRS)

Noor, A. K. (Compiler); Shuart, M. J. (Compiler); Starnes, J. H., Jr. (Compiler); Williams, J. G. (Compiler)

1983-01-01

The state of the art of failure analysis and current design practices, especially as applied to the use of fibrous composite materials in aircraft structures is discussed. Deficiencies in these technologies are identified, as are directions for future research.

Questions Children Ask: Helping Children Adjust When a Parent Has Kidney Failure

MedlinePlus

... Advocacy Donate A to Z Health Guide Questions Children Ask: Helping Children Adjust When a Parent Has Kidney Failure Print ... future plans. If a parent develops kidney failure, children have questions too. Some children are outspoken and ...

Alzheimer's disease prevention: A way forward.

PubMed

Bermejo-Pareja, F; Llamas-Velasco, S; Villarejo-Galende, A

2016-12-01

This review proposes a more optimistic view of Alzheimer's disease (AD), in contrast to that contributed by the ageing of the population and the failure of potentially curative therapies (vaccines and others). Treatment failure is likely due to the fact that AD gestates in the brain for decades but manifests in old age. This review updates the concept of AD and presents the results of recent studies that show that primary prevention can reduce the incidence and delay the onset of the disease. Half of all cases of AD are potentially preventable through education, the control of cardiovascular risk factors, the promotion of healthy lifestyles and specific drug treatments. These approaches could substantially reduce the future incidence rate of this disease. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

Markov and semi-Markov processes as a failure rate

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

Grabski, Franciszek

2016-06-08

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

The economics (or lack thereof) of aerosol geoengineering

NASA Astrophysics Data System (ADS)

Goes, M.; Keller, K.; Tuana, N.

2009-04-01

Anthropogenic greenhouse gas emissions are changing the Earth's climate and impose substantial risks for current and future generations. What are scientifically sound, economically viable, and ethically defendable strategies to manage these climate risks? Ratified international agreements call for a reduction of greenhouse gas emissions to avoid dangerous anthropogenic interference with the climate system. Recent proposals, however, call for the deployment of a different approach: to geoengineer climate by injecting aerosol precursors into the stratosphere. Published economic studies typically suggest that substituting aerosol geoengineering for abatement of carbon dioxide emissions results in large net monetary benefits. However, these studies neglect the risks of aerosol geoengineering due to (i) the potential for future geoengineering failures and (ii) the negative impacts associated with the aerosol forcing. Here we use a simple integrated assessment model of climate change to analyze potential economic impacts of aerosol geoengineering strategies over a wide range of uncertain parameters such as climate sensitivity, the economic damages due to climate change, and the economic damages due to aerosol geoengineering forcing. The simplicity of the model provides the advantages of parsimony and transparency, but it also imposes severe caveats on the interpretation of the results. For example, the analysis is based on a globally aggregated model and is hence silent on the question of intragenerational distribution of costs and benefits. In addition, the analysis neglects the effects of endogenous learning about the climate system. We show that the risks associated with a future geoengineering failure and negative impacts of aerosol forcings can cause geoenginering strategies to fail an economic cost-benefit test. One key to this finding is that a geoengineering failure would lead to dramatic and abrupt climatic changes. The monetary damages due to this failure can dominate the cost-benefit analysis because the monetary damages of climate change are expected to increase with the rate of change. Substituting aerosol geoengineering for greenhouse gas emission abatement might fail not only an economic cost-benefit test but also an ethical test of distributional justice. Substituting aerosol geoengineering for greenhouse gas emissions abatements constitutes a conscious risk transfer to future generations. Intergenerational justice demands distributional justice, namely that present generations may not create benefits for themselves in exchange for burdens on future generations. We use the economic model to quantify this risk transfer to better inform the judgment of whether substituting aerosol geoengineering for carbon dioxide emission abatement fails this ethical test.

Nanoscale Surface Modifications of Orthopaedic Implants: State of the Art and Perspectives

PubMed Central

Staruch, RMT; Griffin, MF; Butler, PEM

2016-01-01

Background: Orthopaedic implants such as the total hip or total knee replacement are examples of surgical interventions with postoperative success rates of over 90% at 10 years. Implant failure is associated with wear particles and pain that requires surgical revision. Improving the implant - bone surface interface is a key area for biomaterial research for future clinical applications. Current implants utilise mechanical, chemical or physical methods for surface modification. Methods: A review of all literature concerning the nanoscale surface modification of orthopaedic implant technology was conducted. Results: The techniques and fabrication methods of nanoscale surface modifications are discussed in detail, including benefits and potential pitfalls. Future directions for nanoscale surface technology are explored. Conclusion: Future understanding of the role of mechanical cues and protein adsorption will enable greater flexibility in surface control. The aim of this review is to investigate and summarise the current concepts and future directions for controlling the implant nanosurface to improve interactions. PMID:28217214

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.

Predicting spatio-temporal failure in large scale observational and micro scale experimental systems

NASA Astrophysics Data System (ADS)

de las Heras, Alejandro; Hu, Yong

2006-10-01

Forecasting has become an essential part of modern thought, but the practical limitations still are manifold. We addressed future rates of change by comparing models that take into account time, and models that focus more on space. Cox regression confirmed that linear change can be safely assumed in the short-term. Spatially explicit Poisson regression, provided a ceiling value for the number of deforestation spots. With several observed and estimated rates, it was decided to forecast using the more robust assumptions. A Markov-chain cellular automaton thus projected 5-year deforestation in the Amazonian Arc of Deforestation, showing that even a stable rate of change would largely deplete the forest area. More generally, resolution and implementation of the existing models could explain many of the modelling difficulties still affecting forecasting.

Hydraulic limits preceding mortality in a piñon-juniper woodland under experimental drought.

PubMed

Plaut, Jennifer A; Yepez, Enrico A; Hill, Judson; Pangle, Robert; Sperry, John S; Pockman, William T; McDowell, Nate G

2012-09-01

Drought-related tree mortality occurs globally and may increase in the future, but we lack sufficient mechanistic understanding to accurately predict it. Here we present the first field assessment of the physiological mechanisms leading to mortality in an ecosystem-scale rainfall manipulation of a piñon-juniper (Pinus edulis-Juniperus monosperma) woodland. We measured transpiration (E) and modelled the transpiration rate initiating hydraulic failure (E(crit) ). We predicted that isohydric piñon would experience mortality after prolonged periods of severely limited gas exchange as required to avoid hydraulic failure; anisohydric juniper would also avoid hydraulic failure, but sustain gas exchange due to its greater cavitation resistance. After 1 year of treatment, 67% of droughted mature piñon died with concomitant infestation by bark beetles (Ips confusus) and bluestain fungus (Ophiostoma spp.); no mortality occurred in juniper or in control piñon. As predicted, both species avoided hydraulic failure, but safety margins from E(crit) were much smaller in piñon, especially droughted piñon, which also experienced chronically low hydraulic conductance. The defining characteristic of trees that died was a 7 month period of near-zero gas exchange, versus 2 months for surviving piñon. Hydraulic limits to gas exchange, not hydraulic failure per se, promoted drought-related mortality in piñon pine. © 2012 Blackwell Publishing Ltd.

[Applying healthcare failure mode and effect analysis to improve the surgical specimen transportation process and rejection rate].

PubMed

Hu, Pao-Hsueh; Hu, Hsiao-Chen; Huang, Hui-Ju; Chao, Hui-Lin; Lei, Ei-Fang

2014-04-01

Because surgical pathology specimens are crucial to the diagnosis and treatment of disease, it is critical that they be collected and transported safely and securely. Due to recent near-miss events in our department, we used the healthcare failure model and effect analysis to identify 14 potential perils in the specimen collection and transportation process. Improvement and prevention strategies were developed accordingly to improve quality of care. Using health care failure mode and effect analysis (HFMEA) may improve the surgical specimen transportation process and reduce the rate of surgical specimen rejection. Rectify standard operating procedures for surgical pathology specimen collection and transportation. Create educational videos and posters. Rectify methods of specimen verification. Organize and create an online and instantaneous management system for specimen tracking and specimen rejection. Implementation of the new surgical specimen transportation process effectively eliminated the 14 identified potential perils. In addition, the specimen rejection fell from 0.86% to 0.03%. This project was applied to improve the specimen transportation process, enhance interdisciplinary cooperation, and improve the patient-centered healthcare system. The creation and implementation of an online information system significantly facilitates specimen tracking, hospital cost reductions, and patient safety improvements. The success in our department is currently being replicated across all departments in our hospital that transport specimens. Our experience and strategy may be applied to inter-hospital specimen transportation in the future.

The impact of chronic kidney disease on medication choice and pharmacologic management in patients with heart failure.

PubMed

Shah, Syed Raza; Winchester, David E

2018-05-21

In the past few years, medical community, including doctors, have become increasingly aware of the fact that chronic kidney disease (CK) and heart failure (HF) have common risk factors which impacts one another in terms of choice of therapy. Areas covered: Management of these two diseases has been a challenge for physicians. The treatment goals for HF patients in CK are very important. They serve as the end-point in using a specific treatment for management and treatment of CK patients hence, decreasing mortality rates. In this review, we discuss the pharmacological approaches to managing patients with HF and CK, discussing current evidence based uptodate management strategies and guidelines in the general population with HF and CK. Expert Commentary: Newer novel drugs targeting specific signaling pathways are approaching the stages of clinical investigation including the direct renin inhibitors. They have been a highly attractive concept for the future in the management of these patients. However, while advances in technology elucidated many aspects of these diseases, many mysteries still remain. With continued research, we can expect more cost- effective and patient-friendly drug therapies to be developed in the near future.

Emotional reactions to success and failure of collective action as predictors of future action intentions: a longitudinal investigation in the context of student protests in Germany.

PubMed

Tausch, Nicole; Becker, Julia C

2013-09-01

This research examined how emotional responses to success and failure of collective action relate to willingness to engage in collective action in the future. It was hypothesized that both pride (in relation to a success) and anger (in response to failure) would motivate future collective action. Findings are reported from a two-wave longitudinal study (N= 98) in the context of student protests against tuition fees in Germany, which was conducted before and after collective action had resulted in both a success and a failure. While anger positively predicted action intentions, over and above baseline action intentions, pride exerted a significant indirect effect on action intentions via increased efficacy perceptions, over and above baseline efficacy and action intentions. Politicized identification positively predicted the intensity of both pride and anger and baseline group efficacy positively predicted the intensity of anger. The theoretical and practical implications of these findings are discussed. © 2012 The British Psychological Society.

Pyrotechnic system failures: Causes and prevention

NASA Technical Reports Server (NTRS)

Bement, Laurence J.

1988-01-01

Although pyrotechnics have successfully accomplished many critical mechanical spacecraft functions, such as ignition, severance, jettisoning and valving (excluding propulsion), failures continue to occur. Provided is a listing of 84 failures of pyrotechnic hardware with completed design over a 23-year period, compiled informally by experts from every NASA Center, as well as the Air Force Space Division and the Naval Surface Warfare Center. Analyses are presented as to when and where these failures occurred, their technical source or cause, followed by the reasons why and how these kinds of failures persist. The major contributor is a fundamental lack of understanding of the functional mechanisms of pyrotechnic devices and systems, followed by not recognizing pyrotechnics as an engineering technology, insufficient manpower with hands-on experience, too few test facilities, and inadequate guidelines and specifications for design, development, qualification and acceptance. Recommendations are made on both a managerial and technical basis to prevent failures, increase reliability, improve existing and future designs, and develop the technology to meet future requirements.

Relative Importance of History of Heart Failure Hospitalization and N-Terminal Pro-B-Type Natriuretic Peptide Level as Predictors of Outcomes in Patients With Heart Failure and Preserved Ejection Fraction.

PubMed

Kristensen, Søren L; Jhund, Pardeep S; Køber, Lars; McKelvie, Robert S; Zile, Michael R; Anand, Inder S; Komajda, Michel; Cleland, John G F; Carson, Peter E; McMurray, John J V

2015-06-01

The aim of this study was to investigate N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and recent heart failure (HF) hospitalization as predictors of future events in heart failure - preserved ejection fraction (HF-PEF). Recently, doubt has been expressed about the value of a history of HF hospitalization as a predictor of adverse cardiovascular outcomes in patients with HF and HF-PEF. We estimated rates and adjusted hazard ratios (HRs) for the composite endpoint of cardiovascular death or HF hospitalization, according to history of recent HF hospitalization and baseline NT-proBNP level in the I-PRESERVE (Irbesartan in Heart Failure with Preserved systolic function) trial. Rates of composite endpoints in patients with (n = 804) and without (n = 1,963) a recent HF hospitalization were 12.78 (95% confidence interval [CI]: 11.47 to 14.24) and 4.49 (95% CI: 4.04 to 4.99) per 100 person-years, respectively (HR: 2.71; 95% CI: 2.33 to 3.16). For patients with NT-proBNP concentrations >360 pg/ml (n = 1,299), the event rate was 11.51 (95% CI: 10.54 to 12.58) compared to 3.04 (95% CI: 2.63 to 3.52) per 100 person-years in those with a lower level of NT-proBNP (n = 1468) (HR: 3.19; 95% CI: 2.68 to 3.80). In patients with no recent HF hospitalization and NT-proBNP ≤360 pg/ml (n = 1,187), the event rate was 2.43 (95% CI: 2.03 to 2.90) compared with 17.79 (95% CI: 15.77 to 20.07) per 100 person-years when both risk predictors were present (n = 523; HR: 6.18; 95% CI: 4.96 to 7.69). Recent hospitalization for HF or an elevated level of NT-proBNP identified patients at higher risk for cardiovascular events, and this risk was increased further when both factors were present. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

How and why of orthodontic bond failures: An in vivo study

PubMed Central

Vijayakumar, R. K.; Jagadeep, Raju; Ahamed, Fayyaz; Kanna, Aprose; Suresh, K.

2014-01-01

Introduction: The bonding of orthodontic brackets and their failure rates by both direct and in-direct procedures are well-documented in orthodontic literature. Over the years different adhesive materials and various indirect bonding transfer procedures have been compared and evaluated for bond failure rates. The aim of our study is to highlight the use of a simple, inexpensive and ease of manipulation of a single thermo-plastic transfer tray and the use the of a single light cure adhesive to evaluate the bond failure rates in clinical situations. Materials and Methods: A total of 30 patients were randomly divided into two groups (Group A and Group B). A split-mouth study design was used, for, both the groups so that they were distributed equally with-out bias. After initial prophylaxis, both the procedures were done as per manufactures instructions. All patients were initially motivated and reviewed for bond failures rates for 6 months. Results: Bond failure rates were assessed for over-all direct and indirect procedures, anterior and posterior arches, and for individual tooth. Z-test was used for statistically analyzing, the normal distribution of the sample in a spilt mouth study. The results of the two groups were compared and P value was calculated using Z-proportion test to assess the significance of the bond failure. Conclusion: Over-all bond failure was more for direct bonding. Anterior bracket failure was more in-direct bonding than indirect procedure, which showed more posterior bracket failures. In individual tooth bond failure, mandibular incisor, and premolar brackets showed more failure, followed by maxillary premolars and canines. PMID:25210392

Does the United States economy affect heart failure readmissions? A single metropolitan center analysis.

PubMed

Thompson, Keith A; Morrissey, Ryan P; Phan, Anita; Schwarz, Ernst R

2012-08-01

To determine the effects of the US economy on heart failure hospitalization rates. The recession was associated with worsening unemployment, loss of private insurance and prescription medication benefits, medication nonadherence, and ultimately increased rates of hospitalization for heart failure. We compared hospitalization rates at a large, single, academic medical center from July 1, 2006 to February 28, 2007, a time of economic stability, and July 1, 2008 to February 28, 2009, a time of economic recession in the United States. Significantly fewer patients had private medical insurance during the economic recession than during the control period (36.5% vs 46%; P = 0.04). Despite this, there were no differences in the heart failure hospitalization or readmission rates, length of hospitalization, need for admission to an intensive care unit, in-hospital mortality, or use of guideline-recommended heart failure medications between the 2 study periods. We conclude that despite significant effects on medical insurance coverage, rates of heart failure hospitalization at our institution were not significantly affected by the recession. Additional large-scale population-based research is needed to better understand the effects of fluctuations in the US economy on heart failure hospitalization rates. © 2012 Wiley Periodicals, Inc.

Surveillance of in vivo resistance of Plasmodium falciparum to antimalarial drugs from 1992 to 1999 in Malabo (Equatorial Guinea).

PubMed

Roche, Jesús; Guerra-Neira, Ana; Raso, José; Benito, Agustîn

2003-05-01

From 1992-1999, we have assessed the therapeutic efficacy of three malaria treatment regimens (chloroquine 25 mg/kg over three days, pyrimethamine/sulfadoxine 1.25/25 mg/kg in one dose, and quinine 25-30 mg/kg daily in three oral doses over a four-, five-, or seven-day period) in 1,189 children under age 10 at Malabo Regional Hospital in Equatorial Guinea. Of those children, 958 were followed up clinically and parasitologically for 14 days. With chloroquine, the failure rate varied from 55% in 1996 to 40% in 1999; the early treatment failure rate increased progressively over the years, from 6% in 1992 to 30% in 1999. With pyrimethamine/sulfadoxine, the failure rate varied from 0% in 1996 to 16% in 1995. The short quinine treatment regimens used in 1992 and 1993 (4 and 5 days, respectively) resulted in significantly higher failure rates (19% and 22%, respectively) than the 7d regimen (3-5.5%). We conclude that: a) failure rates for chloroquine are in the change period (> 25%), and urgent action is needed; b) pyrimethamine/ sulfadoxine failure rates are in the alert period (6-15%), and surveillance must be continued; and c) quinine failure rates are in the grace period (< 6%), so quinine can be recommended.

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

PubMed Central

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

2008-01-01

BACKGROUND Calculating the maximum heart rate for age is one method to characterize the maximum effort of an individual. Although this method is commonly used, little is known about heart rate dynamics in optimized beta-blocked heart failure patients. AIM The aim of this study was to evaluate heart rate dynamics (basal, peak and % heart rate increase) in optimized beta-blocked heart failure patients compared to sedentary, normal individuals (controls) during a treadmill cardiopulmonary exercise test. METHODS Twenty-five heart failure patients (49±11 years, 76% male), with an average LVEF of 30±7%, and fourteen controls were included in the study. Patients with atrial fibrillation, a pacemaker or noncardiovascular functional limitations or whose drug therapy was not optimized were excluded. Optimization was considered to be 50 mg/day or more of carvedilol, with a basal heart rate between 50 to 60 bpm that was maintained for 3 months. RESULTS Basal heart rate was lower in heart failure patients (57±3 bpm) compared to controls (89±14 bpm; p<0.0001). Similarly, the peak heart rate (% maximum predicted for age) was lower in HF patients (65.4±11.1%) compared to controls (98.6±2.2; p<0.0001). Maximum respiratory exchange ratio did not differ between the groups (1.2±0.5 for controls and 1.15±1 for heart failure patients; p=0.42). All controls reached the maximum heart rate for their age, while no patients in the heart failure group reached the maximum. Moreover, the % increase of heart rate from rest to peak exercise between heart failure (48±9%) and control (53±8%) was not different (p=0.157). CONCLUSION No patient in the heart failure group reached the maximum heart rate for their age during a treadmill cardiopulmonary exercise test, despite the fact that the percentage increase of heart rate was similar to sedentary normal subjects. A heart rate increase in optimized beta-blocked heart failure patients during cardiopulmonary exercise test over 65% of the maximum age-adjusted value should be considered an effort near the maximum. This information may be useful in rehabilitation programs and ischemic tests, although further studies are required. PMID:18719758

Resilience Design Patterns - A Structured Approach to Resilience at Extreme Scale (version 1.0)

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

Hukerikar, Saurabh; Engelmann, Christian

Reliability is a serious concern for future extreme-scale high-performance computing (HPC) systems. Projections based on the current generation of HPC systems and technology roadmaps suggest that very high fault rates in future systems. The errors resulting from these faults will propagate and generate various kinds of failures, which may result in outcomes ranging from result corruptions to catastrophic application crashes. Practical limits on power consumption in HPC systems will require future systems to embrace innovative architectures, increasing the levels of hardware and software complexities. The resilience challenge for extreme-scale HPC systems requires management of various hardware and software technologies thatmore » are capable of handling a broad set of fault models at accelerated fault rates. These techniques must seek to improve resilience at reasonable overheads to power consumption and performance. While the HPC community has developed various solutions, application-level as well as system-based solutions, the solution space of HPC resilience techniques remains fragmented. There are no formal methods and metrics to investigate and evaluate resilience holistically in HPC systems that consider impact scope, handling coverage, and performance & power eciency across the system stack. Additionally, few of the current approaches are portable to newer architectures and software ecosystems, which are expected to be deployed on future systems. In this document, we develop a structured approach to the management of HPC resilience based on the concept of resilience-based design patterns. A design pattern is a general repeatable solution to a commonly occurring problem. We identify the commonly occurring problems and solutions used to deal with faults, errors and failures in HPC systems. The catalog of resilience design patterns provides designers with reusable design elements. We define a design framework that enhances our understanding of the important constraints and opportunities for solutions deployed at various layers of the system stack. The framework may be used to establish mechanisms and interfaces to coordinate flexible fault management across hardware and software components. The framework also enables optimization of the cost-benefit trade-os among performance, resilience, and power consumption. The overall goal of this work is to enable a systematic methodology for the design and evaluation of resilience technologies in extreme-scale HPC systems that keep scientific applications running to a correct solution in a timely and cost-ecient manner in spite of frequent faults, errors, and failures of various types.« less

Hybrid boosters for future launch vehicles

NASA Astrophysics Data System (ADS)

Dargies, E.; Lo, R. E.

1987-10-01

Hybrid rocket propulsion systems furnish the advantages of much higher safety levels, due both to shut-down capability in case of ignition failure to one unit and the potential choice of nontoxic propellant combinations, such as LOX/polyethylene; they nevertheless yield performance levels comparable or superior to those of solid rocket boosters. Attention is presently given to the results of DFVLR analytical model studies of hybrid propulsion systems, with attention to solid fuel grain geometrical design and propellant grain surface ablation rate. The safety of hybrid rockets recommends them for use by manned spacecraft.

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

PubMed

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.

Economic and organizational determinants of HMO mergers and failures.

PubMed

Feldman, R; Wholey, D; Christianson, J

1996-01-01

This study analyzed data from all operational health maintenance organizations (HMOs) in the United States from 1986 through 1993. Eighty HMOs disappeared through mergers and 149 failed over that period. We estimated a multinomial logit model to predict whether an HMO would merge and survive, merge and disappear, or fail, relative to the probability of no event. We found that enrollment and profitability play a critical role in explaining HMO mergers and failures: large and profitable HMOs were more likely to merge and survive, but less likely to merge and disappear or fail. These results explain why HMO merger and failure rates fell after 1988, as most surviving HMOs became larger and more profitable. Among several market-area variables in the model, state anti-takeover regulations had a negative impact on mergers. Mergers were more likely in markets with more competing HMOs, but the overall market penetration of HMOs had no effect on mergers. This result may have important implications for the current debate over the future of the competitive health care strategy. If public policy successfully stimulates the development of large numbers of new HMOs, another wave of mergers and failures is likely to occur. But it appears that growth in overall HMO penetration will not lead inevitably to increased market concentration.

Sterilization failures in Singapore: an examination of ligation techniques and failure rates.

PubMed

Cheng, M C; Wong, Y M; Rochat, R W; Ratnam, S S

1977-04-01

The University Department of Obstetrics and Gynecology, Kandang Kerbau Hospital in Singapore, initiated a study in early 1974 of failure rates for various methods of sterilization and the factors responsible for the failures. During the period January 1974 to March 1976, 51 cases of first pregnancy following ligation were discovered. Cumulative failure rates at 24 months were 0.34 per 100 women for abdominal sterilization, 1.67 for culdoscopic, 3.12 for vaginal, and 4.49 for laparoscopic procedures. Findings for 35 patients who underwent religation showed that recanalization and the establishment of a fistulous opening caused the majority of failures. Clearly, more effective methods of tubal occlusion in sterilization are needed.

The Influence of Local Bone Density on the Outcome of One Hundred and Fifty Proximal Humeral Fractures Treated with a Locking Plate.

PubMed

Kralinger, Franz; Blauth, Michael; Goldhahn, Jörg; Käch, Kurt; Voigt, Christine; Platz, Andreas; Hanson, Beate

2014-06-18

There is biomechanical evidence that bone density predicts the mechanical failure of implants. The aim of this prospective study was to evaluate the influence of local bone mineral density on the rate of mechanical failure after locking plate fixation of proximal humeral fractures. We enrolled 150 patients who were from fifty to ninety years old with a closed, displaced proximal humeral fracture fixed with use of a locking plate from July 2007 to April 2010. There were 118 women and thirty-two men who had a mean age of sixty-nine years. Preoperative computed tomography (CT) scans were done to assess bone mineral density of the contralateral humerus, and dual x-ray absorptiometry of the distal end of the radius of the unaffected arm was conducted within the first six weeks postoperatively. At follow-up evaluations at six weeks, three months, and one year postoperatively, pain, shoulder mobility, strength, and multiple functional and quality-of-life outcome measures (Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire; Shoulder Pain and Disability Index [SPADI]; Constant score; and EuroQuol-5D [EQ-5D]) were done and standard radiographs were made. We defined mechanical failure as all complications related to bone quality experienced within one year. After locking plate fixation, fifty-three (35%) of 150 patients had mechanical failure; loss of reduction and secondary screw loosening with perforation were common. CT assessments of local bone mineral density showed no difference between patients with and without mechanical failure (89.82 versus 91.51 mg/cm 3 , respectively; p = 0.670). One-year DASH, SPADI, and Constant scores were significantly better for patients without mechanical failure (p ≤ 0.05). We did not find evidence of an association between bone mineral density and the rate of mechanical failures, which may suggest that patients with normal bone mineral density are less prone to sustain a proximal humeral fracture. Future studies should target other discriminating factors between patients with and without mechanical failure. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

Payload maintenance cost model for the space telescope

NASA Technical Reports Server (NTRS)

White, W. L.

1980-01-01

An optimum maintenance cost model for the space telescope for a fifteen year mission cycle was developed. Various documents and subsequent updates of failure rates and configurations were made. The reliability of the space telescope for one year, two and one half years, and five years were determined using the failure rates and configurations. The failure rates and configurations were also used in the maintenance simulation computer model which simulate the failure patterns for the fifteen year mission life of the space telescope. Cost algorithms associated with the maintenance options as indicated by the failure patterns were developed and integrated into the model.

Rate of change of heart size before congestive heart failure in dogs with mitral regurgitation.

PubMed

Lord, P; Hansson, K; Kvart, C; Häggström, J

2010-04-01

The objective of the study was to examine the changes in vertebral heart scale, and left atrial and ventricular dimensions before and at onset of congestive heart failure in cavalier King Charles spaniels with mitral regurgitation. Records and radiographs from 24 cavalier King Charles spaniels with mitral regurgitation were used. Vertebral heart scale (24 dogs), and left atrial dimension and left ventricular end diastolic and end systolic diameters (18 dogs) and their rate of increase were measured at intervals over years to the onset of congestive heart failure. They were plotted against time to onset of congestive heart failure. Dimensions and rates of change of all parameters were highest at onset of congestive heart failure, the difference between observed and chance outcome being highly significant using a two-tailed chi-square test (P<0.001). The left heart chambers increase in size rapidly only in the last year before the onset of congestive heart failure. Increasing left ventricular end systolic dimension is suggestive of myocardial failure before the onset of congestive heart failure. Rate of increase of heart dimensions may be a useful indicator of impending congestive heart failure.

Liver function assessment using 99mTc-GSA single-photon emission computed tomography (SPECT)/CT fusion imaging in hilar bile duct cancer: A retrospective study.

PubMed

Sumiyoshi, Tatsuaki; Shima, Yasuo; Okabayashi, Takehiro; Kozuki, Akihito; Hata, Yasuhiro; Noda, Yoshihiro; Kouno, Michihiko; Miyagawa, Kazuyuki; Tokorodani, Ryotaro; Saisaka, Yuichi; Tokumaru, Teppei; Nakamura, Toshio; Morita, Sojiro

2016-07-01

The objective of this study was to determine the utility of Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl human serum albumin ((99m)Tc-GSA) single-photon emission computed tomography (SPECT)/CT fusion imaging for posthepatectomy remnant liver function assessment in hilar bile duct cancer patients. Thirty hilar bile duct cancer patients who underwent major hepatectomy with extrahepatic bile duct resection were retrospectively analyzed. Indocyanine green plasma clearance rate (KICG) value and estimated KICG by (99m)Tc-GSA scintigraphy (KGSA) and volumetric and functional rates of future remnant liver by (99m)Tc-GSA SPECT/CT fusion imaging were used to evaluate preoperative whole liver function and posthepatectomy remnant liver function, respectively. Remnant (rem) KICG (= KICG × volumetric rate) and remKGSA (= KGSA × functional rate) were used to predict future remnant liver function; major hepatectomy was considered unsafe for values <0.05. The correlation of remKICG and remKGSA with posthepatectomy mortality and morbidity was determined. Although remKICG and remKGSA were not significantly different (median value: 0.071 vs 0.075), functional rates of future remnant liver were significantly higher than volumetric rates (median: 0.54 vs 0.46; P < .001). Hepatectomy was considered unsafe in 17% and 0% of patients using remKICG and remKGSA, respectively. Postoperative liver failure and mortality did not occur in the patients for whom hepatectomy was considered unsafe based on remKICG. remKGSA showed a stronger correlation with postoperative prothrombin time activity than remKICG. (99m)Tc-GSA SPECT/CT fusion imaging enables accurate assessment of future remnant liver function and suitability for hepatectomy in hilar bile duct cancer patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Is it beneficial to approximate pre-failure topography to predict landslide susceptibility with empirical models?

NASA Astrophysics Data System (ADS)

Steger, Stefan; Schmaltz, Elmar; Glade, Thomas

2017-04-01

Empirical landslide susceptibility maps spatially depict the areas where future slope failures are likely due to specific environmental conditions. The underlying statistical models are based on the assumption that future landsliding is likely to occur under similar circumstances (e.g. topographic conditions, lithology, land cover) as past slope failures. This principle is operationalized by applying a supervised classification approach (e.g. a regression model with a binary response: landslide presence/absence) that enables discrimination between conditions that favored past landslide occurrences and the circumstances typical for landslide absences. The derived empirical relation is then transferred to each spatial unit of an area. Literature reveals that the specific topographic conditions representative for landslide presences are frequently extracted from derivatives of digital terrain models at locations were past landslides were mapped. The underlying morphology-based landslide identification becomes possible due to the fact that the topography at a specific locality usually changes after landslide occurrence (e.g. hummocky surface, concave and steep scarp). In a strict sense, this implies that topographic predictors used within conventional statistical landslide susceptibility models relate to post-failure topographic conditions - and not to the required pre-failure situation. This study examines the assumption that models calibrated on the basis of post-failure topographies may not be appropriate to predict future landslide locations, because (i) post-failure and pre-failure topographic conditions may differ and (ii) areas were future landslides will occur do not yet exhibit such a distinct post-failure morphology. The study was conducted for an area located in the Walgau region (Vorarlberg, western Austria), where a detailed inventory consisting of shallow landslides was available. The methodology comprised multiple systematic comparisons of models generated on the basis of post-failure conditions (i.e. the standard approach) with models based on an approximated pre-failure topography. Pre-failure topography was approximated by (i) erasing the area of mapped landslide polygons within a digital terrain model and (ii) filling these "empty" areas by interpolating elevation points located outside the mapped landslides. Landslide presence information was extracted from the respective landslide scarp locations while an equal number of randomly sampled points represented landslide absences. After an initial exploratory data analysis, mixed-effects logistic regression was applied to model landslide susceptibility on the basis of two predictor sets (post-failure versus pre-failure predictors). Furthermore, all analyses were separately conducted for five different modelling resolutions to elaborate the suspicion that the degree of generalization of topographic parameters may as well play a role on how the respective models may differ. Model evaluation was conducted by means of multiple procedures (i.e. odds ratios, k-fold cross validation, permutation-based variable importance, difference maps of predictions). The results revealed that models based on highest resolutions (e.g. 1 m, 2.5 m) and post-failure topography performed best from a purely quantitative perspective. A confrontation of models (post-failure versus pre-failure based models) based on an identical modelling resolution exposed that validation results, modelled relationships as well as the prediction pattern tended to converge with a decreasing raster resolution. Based on the results, we concluded that an approximation of pre-failure topography does not significantly contribute to improved landslide susceptibility models in the case (i) the underlying inventory consists of small landslide features and (ii) the models are based on coarse raster resolutions (e.g. 25 m). However, in the case modelling with high raster resolutions is envisaged (e.g. 1 m, 2.5 m) or the inventory mainly consists of larger events, a reconstruction of pre-failure conditions might be highly expedient, even though conventional validation results might indicate an opposite tendency. Finally, we recommend to consider that topographic predictors highly useful to detect past slope movements (e.g. roughness) are not necessarily valuable to predict future slope instabilities.

Heart failure and atrial fibrillation: current concepts and controversies.

PubMed Central

Van den Berg, M. P.; Tuinenburg, A. E.; Crijns, H. J.; Van Gelder, I. C.; Gosselink, A. T.; Lie, K. I.

1997-01-01

Heart failure and atrial fibrillation are very common, particularly in the elderly. Owing to common risk factors both disorders are often present in the same patient. In addition, there is increasing evidence of a complex, reciprocal relation between heart failure and atrial fibrillation. Thus heart failure may cause atrial fibrillation, with electromechanical feedback and neurohumoral activation playing an important mediating role. In addition, atrial fibrillation may promote heart failure; in particular, when there is an uncontrolled ventricular rate, tachycardiomyopathy may develop and thereby heart failure. Eventually, a vicious circle between heart failure and atrial fibrillation may form, in which neurohumoral activation and subtle derangement of rate control are involved. Treatment should aim at unloading of the heart, adequate control of ventricular rate, and correction of neurohumoral activation. Angiotensin converting enzyme inhibitors may help to achieve these goals. Treatment should also include an attempt to restore sinus rhythm through electrical cardioversion, though appropriate timing of cardioversion is difficult. His bundle ablation may be used to achieve adequate rate control in drug refractory cases. PMID:9155607

Research and Improvement on Characteristics of Emergency Diesel Generating Set Mechanical Support System in Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Zhe, Yang

2017-06-01

There are often mechanical problems of emergency power generation units in nuclear power plant, which bring a great threat to nuclear safety. Through analyzing the influence factors caused by mechanical failure, the existing defects of the design of mechanical support system are determined, and the design idea has caused the direction misleading in the field of maintenance and transformation. In this paper, research analysis is made on basic support design of diesel generator set, main pipe support design and important components of supercharger support design. And this paper points out the specific design flaws and shortcomings, and proposes targeted improvement program. Through the implementation of improvement programs, vibration level of unit and mechanical failure rate are reduced effectively. At the same time, it also provides guidance for design, maintenance and renovation of diesel generator mechanical support system of nuclear power plants in the future.

Update on the Management of High-Risk Penetrating Keratoplasty.

PubMed

Jabbehdari, Sayena; Rafii, Alireza Baradaran; Yazdanpanah, Ghasem; Hamrah, Pedram; Holland, Edward J; Djalilian, Ali R

2017-03-01

In this article, we review the indications and latest management of high-risk penetrating keratoplasty. Despite the immune-privilege status of the cornea, immune-mediated graft rejection still remains the leading cause of corneal graft failure. This is particularly a problem in the high-risk graft recipients, namely patients with previous graft failure due to rejection and those with inflamed and vascularized corneal beds. A number of strategies including both local and systemic immunosuppression are currently used to increase the success rate of high-risk corneal grafts. Moreover, in cases of limbal stem cell deficiency, limbal stem cells transplantation is employed. Corticosteroids are still the top medication for prevention and treatment in cases of corneal graft rejection. Single and combined administration of immunosuppressive agents e.g. tacrolimus, cyclosporine and mycophenolate are promising adjunctive therapies for prolonging graft survival. In the future, cellular and molecular therapies should allow us to achieve immunologic tolerance even in high-risk grafts.

Myotonic Dystrophy Initially Presenting as Tachycardiomyopathy Successful Catheter Ablation of Atrial Flutter

PubMed Central

Asbach, S.; Gutleben, K. J.; Dahlem, P.; Brachmann, J.; Nölker, G.

2010-01-01

Myotonic dystrophy is a genetic muscular disease that is frequently associated with cardiac arrhythmias. Bradyarrhythmias, such as sinus bradycardia and atrioventricular block, are more common than tachyarrhythmias. Rarely, previously undiagnosed patients with myotonic dystrophy initially present with a tachyarrhythmia. We describe the case of a 14-year-old boy, who was admitted to the hospital with clinical signs and symptoms of decompensated heart failure and severely reduced left ventricular function. Electrocardiography showed common-type atrial flutter with 2 : 1 conduction resulting in a heart rate of 160 bpm. Initiation of medical therapy for heart failure as well as electrical cardioversion led to a marked clinical improvement. Catheter ablation of atrial flutter was performed to prevent future cardiac decompensations and to prevent development of tachymyopathy. Left ventricular function normalized during followup. Genetic analysis confirmed the clinical suspicion of myotonic dystrophy as known in other family members in this case. PMID:20871860

Myocardial recovery during mechanical circulatory support: long-term outcome and elective ventricular assist device implantation to promote recovery as a treatment goal.

PubMed

Dandel, Michael; Hetzer, Roland

2015-01-01

Even after incomplete myocardial recovery during mechanical circulatory support, long-term survival rates after ventricular assist device (VAD) explantation can be better than those expected after heart transplantation even for patients with chronic non-ischemic cardiomyopathy as the underlying cause for VAD implantation. The elective therapeutic use of ventricular assist devices for heart failure reversal in its early stage is a future goal. It may be possible to achieve it by developing tools to predict heart failure reversibility even before ventricular assist device implantation and increasing the number of weaning candidates by improvement of adjunctive therapies to optimize unloading-promoted recovery.  Special attention is focused on the long-term stability of cardiac remission after VAD removal, the clinical relevance unloading-promoted myocardial recovery and on the current knowledge about a potential prediction of myocardial recovery during long-term VAD support already before VAD implantation.

The potential for catastrophic dam failure at Lake Nyos maar, Cameroon

USGS Publications Warehouse

Lockwood, J.P.; Costa, J.E.; Tuttle, M.L.; Nni, J.; Tebor, S.G.

1988-01-01

The upper 40 m of Lake Nyos is bounded on the north by a narrow dam of poorly consolidated pyroclastic rocks, emplaced during the eruptive formation of the Lake Nyos maar a few hundred years ago. This 50-m-wide natural dam is structurally weak and is being eroded at an uncertain, but geologically alarming, rate. The eventual failure of the dam could cause a major flood (estimated peak discharge, 17000 m3/s) that would have a tragic impact on downstream areas as far as Nigeria, 108 km away. This serious hazard could be eliminated by lowering the lake level, either by controlled removal of the dam or by construction of a 680-m-long drainage tunnel about 65 m below the present lake surface. Either strategy would also lessen the lethal effects of future massive CO2 gas releases, such as the one that occurred in August 1986. ?? 1988 Springer-Verlag.

[Differences between German and Turkish-speaking participants in a chronic heart failure management program].

PubMed

Ernstmann, N; Karbach, U

2017-02-01

German and Turkish-speaking patients were recruited for a chronic heart failure management program. So far little is known about the special needs and characteristics of Turkish-speaking patients with chronic heart failure; therefore, the aim of this study was to examine sociodemographic and illness-related differences between German and Turkish-speaking patients with chronic heart failure. German and Turkish-speaking patients suffering from chronic heart failure and insured with the AOK Rheinland/Hamburg or the BARMER GEK health insurance companies and living in Cologne, Germany, were enrolled. Recruitment took place in hospitals, private practices and at information events. Components of the program were coordination of a guideline-oriented medical care, telemonitoring (e.g., blood pressure, electrocardiogram, and weight), a 24-h information hotline, attendance by German and Turkish-speaking nurses and a patient education program. Data were collected by standardized interviews in German or Turkish language. Data were analyzed with descriptive measures and tested for significance differences using Pearson's χ 2 -test and the t‑test. A total of 465 patients (average age 71 years, 55 % male and 33 % Turkish-speaking) were enrolled in the care program during the study period. Significant differences between German and Turkish-speaking patients were found for age, education, employment status, comorbidities, risk perception, knowledge on heart failure and fear of loss of independence. The response rate could be achieved with the help of specific measures for patient enrollment by Turkish-speaking integration nurses. The differences between German and Turkish-speaking patients should in future be taken into account in the care of people with chronic heart failure.

Kidney Failure and ESRD in the Atherosclerosis Risk in Communities (ARIC) Study: Comparing Ascertainment of Treated and Untreated Kidney Failure in a Cohort Study.

PubMed

Rebholz, Casey M; Coresh, Josef; Ballew, Shoshana H; McMahon, Blaithin; Whelton, Seamus P; Selvin, Elizabeth; Grams, Morgan E

2015-08-01

Linkage to the US Renal Data System (USRDS) registry commonly is used to identify end-stage renal disease (ESRD) cases, or kidney failure treated with dialysis or transplantation, but it underestimates the total burden of kidney failure. This study validates a kidney failure definition that includes both kidney failure treated and not treated by dialysis or transplantation. It compares kidney failure risk factors and outcomes using this broader definition with USRDS-identified ESRD risk factors and outcomes. Diagnostic test study with stratified random sampling of hospitalizations for chart review. Atherosclerosis Risk in Communities Study (n=11,530; chart review, n=546). USRDS-identified ESRD; treated or untreated kidney failure defined by USRDS-identified ESRD or International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification (ICD-9-CM/ICD-10-CM) code for hospitalization or death. For ESRD, determination of permanent dialysis therapy or transplantation; for kidney failure, determination of permanent dialysis therapy, transplantation, or estimated glomerular filtration rate < 15 mL/min/1.73 m(2). During 13 years' median follow-up, 508 kidney failure cases were identified, including 173 (34.1%) from the USRDS registry. ESRD and kidney failure incidence were 1.23 and 3.66 cases per 1,000 person-years in the overall population and 1.35 and 6.59 cases per 1,000 person-years among participants older than 70 years, respectively. Other risk-factor associations were similar between ESRD and kidney failure, except diabetes and albuminuria, which were stronger for ESRD. Survivals at 1 and 5 years were 74.0% and 24.0% for ESRD and 59.8% and 31.6% for kidney failure, respectively. Sensitivity and specificity were 88.0% and 97.3% comparing the kidney failure ICD-9-CM/ICD-10-CM code algorithm to chart review; for USRDS-identified ESRD, sensitivity and specificity were 94.9% and 100.0%. Some medical charts were incomplete. A kidney failure definition including treated and untreated disease identifies more cases than linkage to the USRDS registry alone, particularly among older adults. Future studies might consider reporting both USRDS-identified ESRD and a more inclusive kidney failure definition. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Operations analysis (study 2.1). Contingency analysis. [of failure modes anticipated during space shuttle upper stage planning

NASA Technical Reports Server (NTRS)

1974-01-01

Future operational concepts for the space transportation system were studied in terms of space shuttle upper stage failure contingencies possible during deployment, retrieval, or space servicing of automated satellite programs. Problems anticipated during mission planning were isolated using a modified 'fault tree' technique, normally used in safety analyses. A comprehensive space servicing hazard analysis is presented which classifies possible failure modes under the catagories of catastrophic collision, failure to rendezvous and dock, servicing failure, and failure to undock. The failure contingencies defined are to be taken into account during design of the upper stage.

Telehealth Protocol to Prevent Readmission Among High-Risk Patients With Congestive Heart Failure.

PubMed

Rosen, Daniel; McCall, Janice D; Primack, Brian A

2017-11-01

Congestive heart failure is the leading cause of hospital readmissions. We aimed to assess adherence to and effectiveness of a telehealth protocol designed to prevent hospital admissions for congestive heart failure. We recruited a random sample of 50 patients with congestive heart failure (mean age 61 years) from a managed care organization. We developed a telehealth platform allowing for daily, real-time reporting of health status and video conferencing. We defined adherence as the percentage of days on which the patient completed the daily check-in protocol. To assess efficacy, we compared admission and readmission rates between the 6-month intervention period and the prior 6 months. Primary outcomes were admissions and readmissions due to congestive heart failure, and secondary outcomes were admissions and readmissions due to any cause. Forty-eight patients (96%) completed the protocol. Approximately half (46%) were at high risk for readmission according to standardized measures. Median 120-day adherence was 96% (interquartile range, 92%-98%), and adherence did not significantly differ across sex, race, age, living situation, depression, cognitive ability, or risk for readmission. Approximately equal proportions of patients were admitted for all causes during the 6-month intervention period versus the comparison period (37% vs 43%; P = .32). Half as many patients were admitted for congestive heart failure during the 6-month intervention period compared with the comparison period (12% vs 25%; P = .11). Adherence to this telehealth protocol was excellent and consistent, even among high-risk patients. Future research should test the protocol using a more rigorous randomized design. Copyright © 2017 Elsevier Inc. All rights reserved.

Critical Evolution of Damage Toward System-Size Failure in Crystalline Rock

NASA Astrophysics Data System (ADS)

Renard, François; Weiss, Jérôme; Mathiesen, Joachim; Ben-Zion, Yehuda; Kandula, Neelima; Cordonnier, Benoît

2018-02-01

Rock failure under shear loading conditions controls earthquake and faulting phenomena. We study the dynamics of microscale damage precursory to shear faulting in a quartz-monzonite rock representative of crystalline rocks of the continental crust. Using a triaxial rig that is transparent to X-rays, we image the mechanical evolution of centimeter-size core samples by in situ synchrotron microtomography with a resolution of 6.5 μm. Time-lapse three-dimensional images of the samples inside the rig provide a unique data set of microstructural evolution toward faulting. Above a yield point there is a gradual weakening during which microfractures nucleate and grow until this damage span the whole sample. This leads to shear faults oriented about 30° to the main compressive stress in agreement with Anderson's theory and macroscopic failure. The microfractures can be extracted from the three-dimensional images, and their dynamics and morphology (i.e., number, volume, orientation, shape, and largest cluster) are quantified as a function of increasing stress toward failure. The experimental data show for the first time that the total volume of microfractures, the rate of damage growth, and the size of the largest microfracture all increase and diverge when approaching faulting. The average flatness of the microfractures (i.e., the ratio between the second and third eigenvalues of their covariance matrix) shows a significant decrease near failure. The precursors to faulting developing in the future faulting zone are controlled by the evolving microfracture population. Their divergent dynamics toward failure is reminiscent of a dynamical critical transition.

Cost-Effectiveness of Sacubitril-Valsartan Combination Therapy Compared With Enalapril for the Treatment of Heart Failure With Reduced Ejection Fraction.

PubMed

King, Jordan B; Shah, Rashmee U; Bress, Adam P; Nelson, Richard E; Bellows, Brandon K

2016-05-01

The objective of this study was to determine the cost-effectiveness and cost per quality-adjusted life year (QALY) gained of sacubitril-valsartan relative to enalapril for treatment of heart failure with reduced ejection fraction (HFrEF). Compared with enalapril, combination angiotensin receptor-neprilysin inhibition (ARNI), as is found in sacubitril-valsartan, reduces cardiovascular death and heart failure hospitalization rates in patients with HFrEF. Using a Markov model, costs, effects, and cost-effectiveness were estimated for sacubitril-valsartan and enalapril therapies for the treatment of HFrEF. Patients were 60 years of age at model entry and were modeled over a lifetime (40 years) from a third-party payer perspective. Clinical probabilities were derived predominantly from PARADIGM-HF (Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure). All costs and effects were discounted at a 3% rate annually and are presented in 2015 U.S. dollars. In the base case, sacubitril-valsartan, compared with enalapril, was more costly ($60,391 vs. $21,758) and more effective (6.49 vs. 5.74 QALYs) over a lifetime. The cost-effectiveness of sacubitril-valsartan was highly dependent on duration of treatment, ranging from $249,411 per QALY at 3 years to $50,959 per QALY gained over a lifetime. Sacubitril-valsartan may be a cost-effective treatment option depending on the willingness-to-pay threshold. Future investigations should incorporate real-world evidence with sacubitril-valsartan to further inform decision making. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Effects of self-graphing and goal setting on the math fact fluency of students with disabilities.

PubMed

Figarola, Patricia M; Gunter, Philip L; Reffel, Julia M; Worth, Susan R; Hummel, John; Gerber, Brian L

2008-01-01

We evaluated the impact of goal setting and students' participation in graphing their own performance data on the rate of math fact calculations. Participants were 3 students with mild disabilities in the first and second grades; 2 of the 3 students were also identified with Attention-Deficit/Hyperactivity Disorder (ADHD). They were taught to use Microsoft Excel® software to graph their rate of correct calculations when completing timed, independent practice sheets consisting of single-digit mathematics problems. Two students' rates of correct calculations nearly always met or exceeded the aim line established for their correct calculations. Additional interventions were required for the third student. Results are discussed in terms of implications and future directions for increasing the use of evaluation components in classrooms for students at risk for behavior disorders and academic failure.

Urine Fibrosis Markers and Risk of Allograft Failure in Kidney Transplant Recipients: A Case-Cohort Ancillary Study of the FAVORIT Trial.

PubMed

Ix, Joachim H; Katz, Ronit; Bansal, Nisha; Foster, Meredith; Weiner, Daniel E; Tracy, Russell; Jotwani, Vasantha; Hughes-Austin, Jan; McKay, Dianne; Gabbai, Francis; Hsu, Chi-Yuan; Bostom, Andrew; Levey, Andrew S; Shlipak, Michael G

2017-03-01

Kidney tubulointerstitial fibrosis marks risk for allograft failure in kidney transplant recipients, but is poorly captured by estimated glomerular filtration rate (eGFR) or urine albumin-creatinine ratio (ACR). Whether urinary markers of tubulointerstitial fibrosis can noninvasively identify risk for allograft failure above and beyond eGFR and ACR is unknown. Case-cohort study. The FAVORIT (Folic Acid for Vascular Outcome Reduction in Transplantation) Trial was a randomized double-blind trial testing vitamin therapy to lower homocysteine levels in stable kidney transplant recipients. We selected a subset of participants at random (n=491) and all individuals with allograft failure during follow-up (cases; n=257). Using spot urine specimens from the baseline visit, we measured 4 urinary proteins known to correlate with tubulointerstitial fibrosis on biopsy (urine α 1 -microglobulin [A1M], monocyte chemoattractant protein 1 [MCP-1], and procollagen type III and type I amino-terminal amino pro-peptide). Death-censored allograft failure. In models adjusted for demographics, chronic kidney disease risk factors, eGFR, and ACR, higher concentrations of urine A1M (HR per doubling, 1.73; 95% CI, 1.43-2.08) and MCP-1 (HR per doubling, 1.60; 95% CI, 1.32-1.93) were strongly associated with allograft failure. When additionally adjusted for concentrations of other urine fibrosis and several urine injury markers, urine A1M (HR per doubling, 1.76; 95% CI, 1.27-2.44]) and MCP-1 levels (HR per doubling, 1.49; 95% CI, 1.17-1.89) remained associated with allograft failure. Urine procollagen type III and type I levels were not associated with allograft failure. We lack kidney biopsy data, BK titers, and HLA antibody status. Urine measurement of tubulointerstitial fibrosis may provide a noninvasive method to identify kidney transplant recipients at higher risk for future allograft failure, above and beyond eGFR and urine ACR. Published by Elsevier Inc.

Discharge planning for heart failure patients in a tertiary hospital in Shanghai: a best practice implementation project.

PubMed

Chen, Yu; Zhu, Li; Xu, Fei; Chen, Jun

2016-02-01

Heart failure is a major public health concern which contributes significantly to rising healthcare costs. Comprehensive discharge planning can improve health outcomes and reduce readmission rates which, in turn, can lead to cost savings. The aim of this project was to promote best practice in the discharge planning of heart failure patients admitted in the coronary care unit of Zhongshan Hospital. A clinical audit was undertaken using the Joanna Briggs Institute Practical Application of Clinical Evidence System tool. Five audit criteria that represent best practice recommendations for heart failure discharge planning were used. A baseline audit was conducted followed by the implementation of multiple strategies, and the project was finalized with a follow-up audit to determine change in practice. Improvements in practice were observed for all five criteria. The most significant improvements were in the following: completion of a discharge checklist (from 0% to 100% compliance), comprehensive (i.e. inclusion of six topics for self-care) discharge education for patients (from 7% to 100% compliance), and conducting a telephone follow-up (from 0% to 76% compliance). The compliance rates for the two remaining criteria, completion of a structured education for patients and scheduling an outpatient clinic visit, both increased from 93% to 100%.Strategies that were implemented to achieve change in practice included development of a local discharge planning checklist, provision of training for nurses, and development of resources. The project demonstrated positive changes in the discharge planning practices of nurses in the coronary care unit of Zhongshan Hospital. A formalized discharge planning is currently in place and plans for sustaining practice change are underway. A continuous cycle of audit and re-audit will need to be carried out in the future to determine the impact of this evidence implementation activity on heart failure patient outcomes.

Model analysis of the link between interest rates and crashes

NASA Astrophysics Data System (ADS)

Broga, Kristijonas M.; Viegas, Eduardo; Jensen, Henrik Jeldtoft

2016-09-01

We analyse the effect of distinct levels of interest rates on the stability of the financial network under our modelling framework. We demonstrate that banking failures are likely to emerge early on under sustained high interest rates, and at much later stage-with higher probability-under a sustained low interest rate scenario. Moreover, we demonstrate that those bank failures are of a different nature: high interest rates tend to result in significantly more bankruptcies associated to credit losses whereas lack of liquidity tends to be the primary cause of failures under lower rates.

The influence of mandibular skeletal characteristics on inferior alveolar nerve block anesthesia.

PubMed

You, Tae Min; Kim, Kee-Deog; Huh, Jisun; Woo, Eun-Jung; Park, Wonse

2015-09-01

The inferior alveolar nerve block (IANB) is the most common anesthetic techniques in dentistry; however, its success rate is low. The purpose of this study was to determine the correlation between IANB failure and mandibular skeletal characteristics. In total, 693 cases of lower third molar extraction (n = 575 patients) were examined in this study. The ratio of the condylar and coronoid distances from the mandibular foramen (condyle-coronoid ratio [CC ratio]) was calculated, and the mandibular skeleton was then classified as normal, retrognathic, or prognathic. The correlation between IANB failure and sex, treatment side, and the CC ratio was assessed. The IANB failure rates for normal, retrognathic, and prognathic mandibles were 7.3%, 14.5%, and 9.5%, respectively, and the failure rate was highest among those with a CC ratio < 0.8 (severe retrognathic mandible). The failure rate was significantly higher in the retrognathic group than in normal group (P = 0.019), and there was no statistically significant difference between the other two groups. IANB failure could be attributable, in part, to the skeletal characteristics of the mandible. In addition, the failure rate was found to be significantly higher in the retrognathic group.

The influence of mandibular skeletal characteristics on inferior alveolar nerve block anesthesia

PubMed Central

You, Tae Min; Kim, Kee-Deog; Huh, Jisun; Woo, Eun-Jung

2015-01-01

Background The inferior alveolar nerve block (IANB) is the most common anesthetic techniques in dentistry; however, its success rate is low. The purpose of this study was to determine the correlation between IANB failure and mandibular skeletal characteristics Methods In total, 693 cases of lower third molar extraction (n = 575 patients) were examined in this study. The ratio of the condylar and coronoid distances from the mandibular foramen (condyle-coronoid ratio [CC ratio]) was calculated, and the mandibular skeleton was then classified as normal, retrognathic, or prognathic. The correlation between IANB failure and sex, treatment side, and the CC ratio was assessed. Results The IANB failure rates for normal, retrognathic, and prognathic mandibles were 7.3%, 14.5%, and 9.5%, respectively, and the failure rate was highest among those with a CC ratio < 0.8 (severe retrognathic mandible). The failure rate was significantly higher in the retrognathic group than in normal group (P = 0.019), and there was no statistically significant difference between the other two groups. Conclusions IANB failure could be attributable, in part, to the skeletal characteristics of the mandible. In addition, the failure rate was found to be significantly higher in the retrognathic group. PMID:28879267

A quantitative model of honey bee colony population dynamics.

PubMed

Khoury, David S; Myerscough, Mary R; Barron, Andrew B

2011-04-18

Since 2006 the rate of honey bee colony failure has increased significantly. As an aid to testing hypotheses for the causes of colony failure we have developed a compartment model of honey bee colony population dynamics to explore the impact of different death rates of forager bees on colony growth and development. The model predicts a critical threshold forager death rate beneath which colonies regulate a stable population size. If death rates are sustained higher than this threshold rapid population decline is predicted and colony failure is inevitable. The model also predicts that high forager death rates draw hive bees into the foraging population at much younger ages than normal, which acts to accelerate colony failure. The model suggests that colony failure can be understood in terms of observed principles of honey bee population dynamics, and provides a theoretical framework for experimental investigation of the problem.

Early management of patients with acute heart failure: state of the art and future directions. A consensus document from the society for academic emergency medicine/heart failure society of America acute heart failure working group.

PubMed

Collins, Sean; Storrow, Alan B; Albert, Nancy M; Butler, Javed; Ezekowitz, Justin; Felker, G Michael; Fermann, Gregory J; Fonarow, Gregg C; Givertz, Michael M; Hiestand, Brian; Hollander, Judd E; Lanfear, David E; Levy, Phillip D; Pang, Peter S; Peacock, W Frank; Sawyer, Douglas B; Teerlink, John R; Lenihan, Daniel J

2015-01-01

Heart failure (HF) afflicts nearly 6 million Americans, resulting in one million emergency department (ED) visits and over one million annual hospital discharges. An aging population and improved survival from cardiovascular diseases is expected to further increase HF prevalence. Emergency providers play a significant role in the management of patients with acute heart failure (AHF). It is crucial that emergency physicians and other providers involved in early management understand the latest developments in diagnostic testing, therapeutics and alternatives to hospitalization. Further, clinical trials must be conducted in the ED in order to improve the evidence base and drive optimal initial therapy for AHF. Should ongoing and future studies suggest early phenotype-driven therapy improves in-hospital and post-discharge outcomes, ED treatment decisions will need to evolve accordingly. The potential impact of future studies which incorporate risk-stratification into ED disposition decisions cannot be underestimated. Predictive instruments that identify a cohort of patients safe for ED discharge, while simultaneously addressing barriers to successful outpatient management, have the potential to significantly impact quality of life and resource expenditures. Copyright © 2015 Elsevier Inc. All rights reserved.

Skin-Stiffener Debond Prediction Based on Computational Fracture Analysis

NASA Technical Reports Server (NTRS)

Krueger, Ronald; Minguet, Pierre J.; Gates, Tom (Technical Monitor)

2005-01-01

Interlaminar fracture mechanics has proven useful for characterizing the onset of delaminations in composites and has been used with limited success primarily to investigate onset in fracture toughness specimens and laboratory size coupon type specimens. Future acceptance of the methodology by industry and certification authorities however, requires the successful demonstration of the methodology on structural level. For this purpose a panel was selected that is reinforced with stringers. Shear loading causes the panel to buckle and the resulting out-of-plane deformations initiate skin/stringer separation at the location of an embedded defect. For finite element analysis, the panel and surrounding load fixture were modeled with shell elements. A small section of the stringer foot and the panel in the vicinity of the embedded defect were modeled with a local 3D solid model. Across the width of the stringer foot the mixed-mode strain energy release rates were calculated using the virtual crack closure technique. A failure index was calculated by correlating the results with the mixed-mode failure criterion of the graphite/epoxy material. For small applied loads the failure index is well below one across the entire width. With increasing load the failure index approaches one first near the edge of the stringer foot from which delamination is expected to grow. With increasing delamination lengths the buckling pattern of the panel changes and the failure index increases which suggests that rapid delamination growth from the initial defect is to be expected.

Novel Corrosion Sensor for Vision 21 Systems

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

Heng Ban; Bharat Soni

2007-03-31

Advanced sensor technology is identified as a key component for advanced power systems for future energy plants that would have virtually no environmental impact. This project intends to develop a novel high temperature corrosion sensor and subsequent measurement system for advanced power systems. Fireside corrosion is the leading mechanism for boiler tube failures and has emerged to be a significant concern for current and future energy plants due to the introduction of technologies targeting emissions reduction, efficiency improvement, or fuel/oxidant flexibility. Corrosion damage can lead to catastrophic equipment failure, explosions, and forced outages. Proper management of corrosion requires real-time indicationmore » of corrosion rate. However, short-term, on-line corrosion monitoring systems for fireside corrosion remain a technical challenge to date due to the extremely harsh combustion environment. The overall goal of this project is to develop a technology for on-line fireside corrosion monitoring. This objective is achieved by the laboratory development of sensors and instrumentation, testing them in a laboratory muffle furnace, and eventually testing the system in a coal-fired furnace. This project successfully developed two types of sensors and measurement systems, and successful tested them in a muffle furnace in the laboratory. The capacitance sensor had a high fabrication cost and might be more appropriate in other applications. The low-cost resistance sensor was tested in a power plant burning eastern bituminous coals. The results show that the fireside corrosion measurement system can be used to determine the corrosion rate at waterwall and superheater locations. Electron microscope analysis of the corroded sensor surface provided detailed picture of the corrosion process.« less

The Threat of Uncertainty: Why Using Traditional Approaches for Evaluating Spacecraft Reliability are Insufficient for Future Human Mars Missions

NASA Technical Reports Server (NTRS)

Stromgren, Chel; Goodliff, Kandyce; Cirillo, William; Owens, Andrew

2016-01-01

Through the Evolvable Mars Campaign (EMC) study, the National Aeronautics and Space Administration (NASA) continues to evaluate potential approaches for sending humans beyond low Earth orbit (LEO). A key aspect of these missions is the strategy that is employed to maintain and repair the spacecraft systems, ensuring that they continue to function and support the crew. Long duration missions beyond LEO present unique and severe maintainability challenges due to a variety of factors, including: limited to no opportunities for resupply, the distance from Earth, mass and volume constraints of spacecraft, high sensitivity of transportation element designs to variation in mass, the lack of abort opportunities to Earth, limited hardware heritage information, and the operation of human-rated systems in a radiation environment with little to no experience. The current approach to maintainability, as implemented on ISS, which includes a large number of spares pre-positioned on ISS, a larger supply sitting on Earth waiting to be flown to ISS, and an on demand delivery of logistics from Earth, is not feasible for future deep space human missions. For missions beyond LEO, significant modifications to the maintainability approach will be required.Through the EMC evaluations, several key findings related to the reliability and safety of the Mars spacecraft have been made. The nature of random and induced failures presents significant issues for deep space missions. Because spare parts cannot be flown as needed for Mars missions, all required spares must be flown with the mission or pre-positioned. These spares must cover all anticipated failure modes and provide a level of overall reliability and safety that is satisfactory for human missions. This will require a large amount of mass and volume be dedicated to storage and transport of spares for the mission. Further, there is, and will continue to be, a significant amount of uncertainty regarding failure rates for spacecraft components. This uncertainty makes it much more difficult to anticipate failures and will potentially require an even larger amount of spares to provide an acceptable level of safety. Ultimately, the approach to maintenance and repair applied to ISS, focusing on the supply of spare parts, may not be tenable for deep space missions. Other approaches, such as commonality of components, simplification of systems, and in-situ manufacturing will be required.

Pediatric Hydrocephalus in Ethiopia: Treatment Failures and Infections: A Hospital-Based, Retrospective Study.

PubMed

Laeke, Tsegazeab; Tirsit, Abenezer; Biluts, Hagos; Murali, Deeptha; Wester, Knut

2017-04-01

Treatment of pediatric hydrocephalus in sub-Saharan countries is associated with significant complication rates. The objective of this study is to analyze the management of hydrocephalus and complication rates of surgical intervention in the Ethiopian setting to improve future quality. A retrospective cohort study was conducted in a neurosurgical teaching hospital. Two cohorts separated by 2.5 years were analyzed. A total of 128 (58.6% male and 41.4% female) children with isolated hydrocephalus, meningomyelocele (MMC)-related hydrocephalus, or MMC without hydrocephalus were included. Their age ranged from 1 day to 5 years, for a mean age of 7.2 months (median age 2 months). One hundred thirteen patients had hydrocephalus, of whom 57 (44.5.3%) had isolated hydrocephalus and 56 (43.8%) had hydrocephalus associated with MMC. Seventy-seven (74.7%) patients underwent ventriculoperitoneal (VP) shunting, whereas 24 (23.3%) underwent endoscopic third ventriculostomy (ETV). The incidence of shunt infection was 23.4%. Reoperation was needed in 54 (52.4%) patients, with the most common indication being shunt failure. ETV failed in 14 (58.3%) of the 24 patients undergoing ETV. VP shunt insertions had unacceptably high infection rate despite the presence of a protocol for the procedure. Intraoperative guidelines should be developed further and followed strictly to reduce infections. Such measures should include restricting the number of surgeons performing the procedure. In our opinion, one should avoid insertion of a VP shunt as the primary treatment. ETV has proved to be a good alternative in other studies and the decreasing pattern of ETV failure in our study also suggest ETV as a better alternative to VP shunt. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Risk factors for eye bank preparation failure of Descemet membrane endothelial keratoplasty tissue.

PubMed

Vianna, Lucas M M; Stoeger, Christopher G; Galloway, Joshua D; Terry, Mark; Cope, Leslie; Belfort, Rubens; Jun, Albert S

2015-05-01

To assess the results of a single eye bank preparing a high volume of Descemet membrane endothelial keratoplasty (DMEK) tissues using multiple technicians to provide an overview of the experience and to identify possible risk factors for DMEK preparation failure. Cross-sectional study. setting: Lions VisionGift and Wilmer Eye Institute at Johns Hopkins Hospital. All 563 corneal tissues processed by technicians at Lions VisionGift for DMEK between October 2011 and May 2014 inclusive. Tissues were divided into 2 groups: DMEK preparation success and DMEK preparation failure. We compared donor characteristics, including past medical history. The overall tissue preparation failure rate was 5.2%. Univariate analysis showed diabetes mellitus (P = .000028) and its duration (P = .023), hypertension (P = .021), and hyperlipidemia or obesity (P = .0004) were more common in the failure group. Multivariate analysis showed diabetes mellitus (P = .0001) and hyperlipidemia or obesity (P = .0142) were more common in the failure group. Elimination of tissues from donors either with diabetes or with hyperlipidemia or obesity reduced the failure rate from 5.2% to 2.2%. Trends toward lower failure rates occurring with increased technician experience also were found. Our work showed that tissues from donors with diabetes mellitus (especially with longer disease duration) and hyperlipidemia or obesity were associated with higher failure rates in DMEK preparation. Elimination of tissues from donors either with diabetes mellitus or with hyperlipidemia or obesity reduced the failure rate. In addition, our data may provide useful initial guidelines and benchmark values for eye banks seeking to establish and maintain DMEK programs. Copyright © 2015 Elsevier Inc. All rights reserved.

Reliability and Maintainability Analysis for the Amine Swingbed Carbon Dioxide Removal System

NASA Technical Reports Server (NTRS)

Dunbar, Tyler

2016-01-01

I have performed a reliability & maintainability analysis for the Amine Swingbed payload system. The Amine Swingbed is a carbon dioxide removal technology that has gone through 2,400 hours of International Space Station on-orbit use between 2013 and 2016. While the Amine Swingbed is currently an experimental payload system, the Amine Swingbed may be converted to system hardware. If the Amine Swingbed becomes system hardware, it will supplement the Carbon Dioxide Removal Assembly (CDRA) as the primary CO2 removal technology on the International Space Station. NASA is also considering using the Amine Swingbed as the primary carbon dioxide removal technology for future extravehicular mobility units and for the Orion, which will be used for the Asteroid Redirect and Journey to Mars missions. The qualitative component of the reliability and maintainability analysis is a Failure Modes and Effects Analysis (FMEA). In the FMEA, I have investigated how individual components in the Amine Swingbed may fail, and what the worst case scenario is should a failure occur. The significant failure effects are the loss of ability to remove carbon dioxide, the formation of ammonia due to chemical degradation of the amine, and loss of atmosphere because the Amine Swingbed uses the vacuum of space to regenerate the Amine Swingbed. In the quantitative component of the reliability and maintainability analysis, I have assumed a constant failure rate for both electronic and nonelectronic parts. Using this data, I have created a Poisson distribution to predict the failure rate of the Amine Swingbed as a whole. I have determined a mean time to failure for the Amine Swingbed to be approximately 1,400 hours. The observed mean time to failure for the system is between 600 and 1,200 hours. This range includes initial testing of the Amine Swingbed, as well as software faults that are understood to be non-critical. If many of the commercial parts were switched to military-grade parts, the expected mean time to failure would be 2,300 hours. Both calculated mean times to failure for the Amine Swingbed use conservative failure rate models. The observed mean time to failure for CDRA is 2,500 hours. Working on this project and for NASA in general has helped me gain insight into current aeronautics missions, reliability engineering, circuit analysis, and different cultures. Prior my internship, I did not have a lot knowledge about the work being performed at NASA. As a chemical engineer, I had not really considered working for NASA as a career path. By engaging in interactions with civil servants, contractors, and other interns, I have learned a great deal about modern challenges that NASA is addressing. My work has helped me develop a knowledge base in safety and reliability that would be difficult to find elsewhere. Prior to this internship, I had not thought about reliability engineering. Now, I have gained a skillset in performing reliability analyses, and understanding the inner workings of a large mechanical system. I have also gained experience in understanding how electrical systems work while I was analyzing the electrical components of the Amine Swingbed. I did not expect to be exposed to as many different cultures as I have while working at NASA. I am referring to both within NASA and the Houston area. NASA employs individuals with a broad range of backgrounds. It has been great to learn from individuals who have highly diverse experiences and outlooks on the world. In the Houston area, I have come across individuals from different parts of the world. Interacting with such a high number of individuals with significantly different backgrounds has helped me to grow as a person in ways that I did not expect. My time at NASA has opened a window into the field of aeronautics. After earning a bachelor's degree in chemical engineering, I plan to go to graduate school for a PhD in engineering. Prior to coming to NASA, I was not aware of the graduate Pathways program. I intend to apply for the graduate Pathways program as positions are opened up. I would like to pursue future opportunities with NASA, especially as my engineering career progresses.

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…

Training of residents in laparoscopic tubal sterilization: Long-term failure rates

PubMed Central

Rackow, Beth W.; Rhee, Maria C.; Taylor, Hugh S.

2011-01-01

Objectives Laparoscopic tubal sterilization with bipolar coagulation is a common and effective method of contraception, and a procedure much used to teach laparoscopic surgical skills to Obstetrics and Gynaecology residents (trainees); but it has an inherent risk of failure. This study investigated the long-term failure rate of this procedure when performed by Obstetrics and Gynaecology residents on women treated in their teaching clinics. Methods From 1991 to 1994, Obstetrics and Gynaecology residents carried out 386 laparoscopic tubal sterilizations with bipolar coagulation at Yale-New Haven Hospital. Six to nine years after the procedure, the women concerned were contacted by telephone and data were collected about sterilization failure. Results Two failures of laparoscopic tubal sterilization with bipolar coagulation were identified: an ectopic pregnancy and a spontaneous abortion. For this time period, the long-term sterilization failure rate was 1.9% (0–4.4%). Conclusions The long-term sterilization failure rate for laparoscopic tubal sterilization with bipolar coagulation performed by residents is comparable to the results of prior studies. These findings can be used to properly counsel women at a teaching clinic about the risks of sterilization failure with this procedure, and attest to the adequacy of residents’ training and supervision. PMID:18465476

Vascular access in lipoprotein apheresis: a retrospective analysis from the UK's largest lipoprotein apheresis centre.

PubMed

Doherty, Daniel J; Pottle, Alison; Malietzis, George; Hakim, Nadey; Barbir, Mahmoud; Crane, Jeremy S

2018-01-01

Lipoprotein apheresis (LA) has proven to be an effective, safe and life-saving therapy. Vascular access is needed to facilitate this treatment but has recognised complications. Despite consistency in treatment indication and duration there are no guidelines in place. The aim of this study is to characterise vascular access practice at the UK's largest LA centre and forward suggestions for future approaches. A retrospective analysis of vascular access strategies was undertaken in all patients who received LA treatment in the low-density lipoprotein (LDL) Apheresis Unit at Harefield Hospital (Middlesex, UK) from November 2000 to March 2016. Fifty-three former and current patients underwent 4260 LA treatments. Peripheral vein cannulation represented 79% of initial vascular access strategies with arteriovenous (AV) fistula use accounting for 15%. Last used method of vascular access was peripheral vein cannulation in 57% versus AV fistula in 32%. Total AV fistula failure rate was 37%. Peripheral vein cannulation remains the most common method to facilitate LA. Practice trends indicate a move towards AV fistula creation; the favoured approach receiving support from the expert body in this area. AV fistula failure rate is high and of great concern, therefore we suggest the implementation of upper limb ultrasound vascular mapping in all patients who meet treatment eligibility criteria. We encourage close ties between apheresis units and specialist surgical centres to facilitate patient counselling and monitoring. Further prospective data regarding fistula failure is needed in this expanding treatment field.

An analysis of the value of spermicides in contraception.

PubMed

1979-11-01

Development of the so-called modern methods of contraception has somewhat eclipsed interest in traditional methods. However, spermicides are still important for many couples and their use appears to be increasing. A brief history of the use of and research into spermicidal contraceptives is presented. The limitations of spermicides are: the necessity for use at the time of intercourse, and their high failure rate. Estimates of the failure rates of spermicides have ranged from .3 pregnancies per 100 woman-years of use to nearly 40, depending on the product used and the population tested. Just as their use depends on various social factors, so does their failure rate. Characteristics of the user deterine failure rates. Motivation is important in lowering failure rates as is education, the intracouple relationship, and previous experience with spermicides. Method failure is also caused by defects in the product, either in the active ingredient of the spermicide or in the base carrier. The main advantage of spermicidal contraception is its safety. Limited research is currently being conducted on spermicides. Areas for improvement in existing spermicides and areas for possible innovation are mentioned.

Failure: A Source of Progress in Maintenance and Design

NASA Astrophysics Data System (ADS)

Chaïb, R.; Taleb, M.; Benidir, M.; Verzea, I.; Bellaouar, A.

This approach, allows using the failure as a source of progress in maintenance and design to detect the most critical components in equipment, to determine the priority order maintenance actions to lead and direct the exploitation procedure towards the most penalizing links in this equipment, even define the necessary changes and recommendations for future improvement. Thus, appreciate the pathological behaviour of the material and increase its availability, even increase its lifespan and improve its future design. In this context and in the light of these points, the failures are important in managing the maintenance function. Indeed, it has become important to understand the phenomena of failure and degradation of equipments in order to establish an appropriate maintenance policy for the rational use of mechanical components and move to the practice of proactive maintenance [1], do maintenance at the design [2].

FATIGUE OF DENTAL CERAMICS

PubMed Central

Zhang, Yu; Sailer, Irena; Lawn, Brian R

2013-01-01

Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

Fatigue of dental ceramics.

PubMed

Zhang, Yu; Sailer, Irena; Lawn, Brian R

2013-12-01

Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. Copyright © 2013 Elsevier Ltd. All rights reserved.

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.

Comprehensive in-hospital monitoring in acute heart failure: applications for clinical practice and future directions for research. A statement from the Acute Heart Failure Committee of the Heart Failure Association (HFA) of the European Society of Cardiology (ESC).

PubMed

Harjola, Veli-Pekka; Parissis, John; Brunner-La Rocca, Hans-Peter; Čelutkienė, Jelena; Chioncel, Ovidiu; Collins, Sean P; De Backer, Daniel; Filippatos, Gerasimos S; Gayat, Etienne; Hill, Loreena; Lainscak, Mitja; Lassus, Johan; Masip, Josep; Mebazaa, Alexandre; Miró, Òscar; Mortara, Andrea; Mueller, Christian; Mullens, Wilfried; Nieminen, Markku S; Rudiger, Alain; Ruschitzka, Frank; Seferovic, Petar M; Sionis, Alessandro; Vieillard-Baron, Antoine; Weinstein, Jean Marc; de Boer, Rudolf A; Crespo Leiro, Maria G; Piepoli, Massimo; Riley, Jillian P

2018-04-30

This paper provides a practical clinical application of guideline recommendations relating to the inpatient monitoring of patients with acute heart failure, through the evaluation of various clinical, biomarker, imaging, invasive and non-invasive approaches. Comprehensive inpatient monitoring is crucial to the optimal management of acute heart failure patients. The European Society of Cardiology heart failure guidelines provide recommendations for the inpatient monitoring of acute heart failure, but the level of evidence underpinning most recommendations is limited. Many tools are available for the in-hospital monitoring of patients with acute heart failure, and each plays a role at various points throughout the patient's treatment course, including the emergency department, intensive care or coronary care unit, and the general ward. Clinical judgment is the preeminent factor guiding application of inpatient monitoring tools, as the various techniques have different patient population targets. When applied appropriately, these techniques enable decision making. However, there is limited evidence demonstrating that implementation of these tools improves patient outcome. Research priorities are identified to address these gaps in evidence. Future research initiatives should aim to identify the optimal in-hospital monitoring strategies that decrease morbidity and prolong survival in patients with acute heart failure. © 2018 The Authors. European Journal of Heart Failure © 2018 European Society of Cardiology.

Complications of short versus long cephalomedullary nail for intertrochanteric femur fractures, minimum 1 year follow-up.

PubMed

Vaughn, Josh; Cohen, Eric; Vopat, Bryan G; Kane, Patrick; Abbood, Emily; Born, Christopher

2015-05-01

Hip fractures are becoming increasingly common resulting in significant morbidity, mortality and raising healthcare costs. Both short and long cephalomedullary devices are currently employed to treat intertrochanteric hip fractures. However, which device is optimal continues to be debated as each implant has unique characteristics and theoretical advantages. This study looked to identify rates of complications associated with both long and short cephalomedullary nails for the treatment of intertrochanteric hip fractures. We retrospectively reviewed charts from 2006 to 2011, and we identified 256 patients were identified with AO class 31.1-32.3 fractures. Sixty were treated with short nails and 196 with long nails. Radiographs and charts were then analysed for failures and hardware complications. Catastrophic failure and hardware complication rates were not statistically different between short or long cephalomedullary nails. The overall catastrophic failure rate was 3.1 %; there was a 5 % failure rate in the short-nail group compared with a 2.6 % failure rate in the long-nail group (p = 0.191). There was a 3.33 % secondary femur fracture rate in the short-nail group, compared with none in the long-nail cohort (p = 0.054). The rate of proximal fixation failure was 1.67 % for the short-nail group and 2.0 % in the long-nail group (p = 0.406). Our data suggests equivocal outcomes as measured by similar catastrophic failure rate between both short and long cephalomedullary nails for intertrochanteric femur fractures. However, there was an increased risk of secondary femur fracture with short cephalomedullary nails when compared to long nails that approached statistical significance.

[Biochemical failure after curative treatment for localized prostate cancer].

PubMed

Zouhair, Abderrahim; Jichlinski, Patrice; Mirimanoff, René-Olivier

2005-12-07

Biochemical failure after curative treatment for localized prostate cancer is frequent. The diagnosis of biochemical failure is clear when PSA levels rise after radical prostatectomy, but may be more difficult after external beam radiation therapy. The main difficulty once biochemical failure is diagnosed is to distinguish between local and distant failure, given the low sensitivity of standard work-up exams. Metabolic imaging techniques currently under evaluation may in the future help us to localize the site of failures. There are several therapeutic options depending on the initial curative treatment, each with morbidity risks that should be considered in multidisciplinary decision-making.

A Novel Risk Stratification to Predict Local-Regional Failures in Urothelial Carcinoma of the Bladder After Radical Cystectomy

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

Baumann, Brian C.; Guzzo, Thomas J.; He Jiwei

2013-01-01

Purpose: Local-regional failures (LF) following radical cystectomy (RC) plus pelvic lymph node dissection (PLND) with or without chemotherapy for invasive urothelial bladder carcinoma are more common than previously reported. Adjuvant radiation therapy (RT) could reduce LF but currently has no defined role because of previously reported morbidity. Modern techniques with improved normal tissue sparing have rekindled interest in RT. We assessed the risk of LF and determined those factors that predict recurrence to facilitate patient selection for future adjuvant RT trials. Methods and Materials: From 1990-2008, 442 patients with urothelial bladder carcinoma at University of Pennsylvania were prospectively followed aftermore » RC plus PLND with or without chemotherapy with routine pelvic computed tomography (CT) or magnetic resonance imaging (MRI). One hundred thirty (29%) patients received chemotherapy. LF was any pelvic failure detected before or within 3 months of distant failure. Competing risk analyses identified factors predicting increased LF risk. Results: On univariate analysis, pathologic stage {>=}pT3, <10 nodes removed, positive margins, positive nodes, hydronephrosis, lymphovascular invasion, and mixed histology significantly predicted LF; node density was marginally predictive, but use of chemotherapy, number of positive nodes, type of surgical diversion, age, gender, race, smoking history, and body mass index were not. On multivariate analysis, only stage {>=}pT3 and <10 nodes removed were significant independent LF predictors with hazard ratios of 3.17 and 2.37, respectively (P<.01). Analysis identified 3 patient subgroups with significantly different LF risks: low-risk ({<=}pT2), intermediate-risk ({>=}pT3 and {>=}10 nodes removed), and high-risk ({>=}pT3 and <10 nodes) with 5-year LF rates of 8%, 23%, and 42%, respectively (P<.01). Conclusions: This series using routine CT and MRI surveillance to detect LF confirms that such failures are relatively common in cases of locally advanced disease and provides a rubric based on pathological stage and number of nodes removed that stratifies patients into 3 groups with significantly different LF risks to simplify patient selection for future adjuvant radiation therapy trials.« less

Pressures, trends, and impacts in coastal zones: Interactions between socioeconomic and natural systems

NASA Astrophysics Data System (ADS)

Turner, R. K.; Subak, S.; Adger, W. N.

1996-03-01

This paper assesses the status of coastal zones in the context of expected climate change and its related impacts, as well as current and future socioeconomic pressures and impacts. It is argued that external stresses and shocks relating to sea-level rise and other changes will tend to exacerbate existing environmental pressures and damage in coastal zones. Coastal zones are under increasing stress because of an interrelated set of planning failures including information, economic market, and policy intervention failures. Moves towards integrated coastal zone management are urgently required to guide the coevolution of natural and human systems. Overtly technocentric claims that assessments of vulnerability undertaken to date are overestimates of likely future damages from global warming are premature. While it is the case that forecasts of sea-level rise have been scaled down, much uncertainty remains over, for example, combined storm, sea surge, and other events. In any case, within the socioeconomic analyses of the problem, resource valuations have been at best only partial and have failed to incorporate sensitivity analysis in terms of the discount rates utilized. This would indicate an underestimation of potential damage costs. Overall, a precautionary approach is justified based on the need to act ahead of adequate information acquisition, economically efficient resource pricing and proactive coastal planning.

Photovoltaic failure and degradation modes

DOE PAGES

Jordan, Dirk C.; Silverman, Timothy J.; Wohlgemuth, John H.; ...

2017-01-30

The extensive photovoltaic field reliability literature was analyzed and reviewed. Future work is prioritized based upon information assembled from recent installations, and inconsistencies in degradation mode identification are discussed to help guide future publication on this subject. Reported failure rates of photovoltaic modules fall mostly in the range of other consumer products; however, the long expected useful life of modules may not allow for direct comparison. In general, degradation percentages are reported to decrease appreciably in newer installations that are deployed after the year 2000. However, these trends may be convoluted with varying manufacturing and installation quality world-wide. Modules inmore » hot and humid climates show considerably higher degradation modes than those in desert and moderate climates, which warrants further investigation. Delamination and diode/j-box issues are also more frequent in hot and humid climates than in other climates. The highest concerns of systems installed in the last 10 years appear to be hot spots followed by internal circuitry discoloration. Encapsulant discoloration was the most common degradation mode, particularly in older systems. In newer systems, encapsulant discoloration appears in hotter climates, but to a lesser degree. Lastly, thin-film degradation modes are dominated by glass breakage and absorber corrosion, although the breadth of information for thin-film modules is much smaller than for x-Si.« less

Ice-Cliff Failure via Retrogressive Slumping

NASA Astrophysics Data System (ADS)

Parizek, B. R.; Christianson, K.; Alley, R. B.; Voytenko, D.; Vankova, I.; Dixon, T. H.; Holland, D.

2016-12-01

The magnitude and rate of future sea-level rise from warming-induced ice-sheet shrinkage remain notably uncertain. Removal of most of an ice sheet by surface melting alone requires centuries to millennia. Oceanic warming may accelerate loss by removing buttressing ice shelves and thereby speeding flow of non-floating ice into the ocean, but, until recently, modeled timescales for major dynamic ice-sheet shrinkage were centuries or longer. Beyond certain thresholds, however, observations show that warming removes floating ice shelves, leaving grounded ice cliffs from which icebergs break off directly. Cliffs higher than some limit experience rapid structural failure. Recent parameterization of this process in a comprehensive ice-flow model produced much faster sea-level rise from future rapid warming than in previous modeling studies, through formation and retreat of tall ice cliffs. Fully physical representations of this process are not yet available, however. Here, we use modeling guided by terrestrial radar data from Helheim Glacier, Greenland to show that cliffs will fail by slumping and trigger rapid retreat at a threshold height that, in crevassed ice with surface melting, may be only slightly above the 100-m maximum observed today, but may be roughly twice that (180-275 m) in mechanically-competent ice under well-drained or low-melt conditions.

Photovoltaic failure and degradation modes

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

Jordan, Dirk C.; Silverman, Timothy J.; Wohlgemuth, John H.

The extensive photovoltaic field reliability literature was analyzed and reviewed. Future work is prioritized based upon information assembled from recent installations, and inconsistencies in degradation mode identification are discussed to help guide future publication on this subject. Reported failure rates of photovoltaic modules fall mostly in the range of other consumer products; however, the long expected useful life of modules may not allow for direct comparison. In general, degradation percentages are reported to decrease appreciably in newer installations that are deployed after the year 2000. However, these trends may be convoluted with varying manufacturing and installation quality world-wide. Modules inmore » hot and humid climates show considerably higher degradation modes than those in desert and moderate climates, which warrants further investigation. Delamination and diode/j-box issues are also more frequent in hot and humid climates than in other climates. The highest concerns of systems installed in the last 10 years appear to be hot spots followed by internal circuitry discoloration. Encapsulant discoloration was the most common degradation mode, particularly in older systems. In newer systems, encapsulant discoloration appears in hotter climates, but to a lesser degree. Lastly, thin-film degradation modes are dominated by glass breakage and absorber corrosion, although the breadth of information for thin-film modules is much smaller than for x-Si.« less

Artificial Immune System for Flight Envelope Estimation and Protection

DTIC Science & Technology

2014-12-31

Throttle Failure 103 5.3. Estimation Algorithms for Sensor AC 108 5.3.1. Roll Rate Sensor Bias 108...4.13. Reference Features-Pattern for a Roll Rate Sensor Under Low Severity Failure 93 Figure 4.14. Reference Features-Pattern for a Roll Rate...Average PI for Different ACs 134 Figure 6.9. Roll Response Under High Magnitude Stabilator Failure 135 Figure 6.10. Pitch

The ABCs of managing systolic heart failure: Past, present, and future.

PubMed

Okwuosa, Ike Stanley; Princewill, Oluseyi; Nwabueze, Chiemeke; Mathews, Lena; Hsu, Steven; Gilotra, Nisha A; Lewsey, Sabra; Blumenthal, Roger S; Russell, Stuart D

2016-10-01

Heart failure management is complex and constantly evolving. The American College of Cardiology and the American Heart Association (ACC/AHA) last issued evidence-based guidelines in 2013, and since then, new drugs and devices have been developed. This review presents an evidence-based approach to current heart failure management. Copyright © 2016 Cleveland Clinic.

A Literature Review of School Practices to Overcome School Failure. OECD Education Working Papers, No. 68

ERIC Educational Resources Information Center

Faubert, Brenton

2012-01-01

The purpose of this report is to review the body of literature concerned with reducing school failure by improving equity in schools and classrooms. The literature review will be used to inform the Organisation for Economic Cooperation and Development (OECD) Project "Overcoming School Failure: Policies that Work" and hopefully, future educational…

Preeclampsia and Future Cardiovascular Health: A Systematic Review and Meta-Analysis.

PubMed

Wu, Pensée; Haththotuwa, Randula; Kwok, Chun Shing; Babu, Aswin; Kotronias, Rafail A; Rushton, Claire; Zaman, Azfar; Fryer, Anthony A; Kadam, Umesh; Chew-Graham, Carolyn A; Mamas, Mamas A

2017-02-01

Preeclampsia is a pregnancy-specific disorder resulting in hypertension and multiorgan dysfunction. There is growing evidence that these effects persist after pregnancy. We aimed to systematically evaluate and quantify the evidence on the relationship between preeclampsia and the future risk of cardiovascular diseases. We studied the future risk of heart failure, coronary heart disease, composite cardiovascular disease, death because of coronary heart or cardiovascular disease, stroke, and stroke death after preeclampsia. A systematic search of MEDLINE and EMBASE was performed to identify relevant studies. We used random-effects meta-analysis to determine the risk. Twenty-two studies were identified with >6.4 million women including >258 000 women with preeclampsia. Meta-analysis of studies that adjusted for potential confounders demonstrated that preeclampsia was independently associated with an increased risk of future heart failure (risk ratio [RR], 4.19; 95% confidence interval [CI], 2.09-8.38), coronary heart disease (RR, 2.50; 95% CI, 1.43-4.37), cardiovascular disease death (RR, 2.21; 95% CI, 1.83-2.66), and stroke (RR, 1.81; 95% CI, 1.29-2.55). Sensitivity analyses showed that preeclampsia continued to be associated with an increased risk of future coronary heart disease, heart failure, and stroke after adjusting for age (RR, 3.89; 95% CI, 1.83-8.26), body mass index (RR, 3.16; 95% CI, 1.41-7.07), and diabetes mellitus (RR, 4.19; 95% CI, 2.09-8.38). Preeclampsia is associated with a 4-fold increase in future incident heart failure and a 2-fold increased risk in coronary heart disease, stroke, and death because of coronary heart or cardiovascular disease. Our study highlights the importance of lifelong monitoring of cardiovascular risk factors in women with a history of preeclampsia. © 2017 American Heart Association, Inc.

Risk Management in the Human Spaceflight Program

NASA Technical Reports Server (NTRS)

Hoffman, William

2009-01-01

The contents include:1) NASA Mission and Organization; 2) Major Mission Failures and Causes; 3) Cultural Changes Resulting from Failures; 3) Safety at NASA Today; 4) Best Safety Practices; 5) Safety Challenges; and 6) Future Commitment.

Innovations in cardiac transplantation.

PubMed

Hasan, Reema; Ela, Ashraf Abou El; Goldstein, Daniel

2017-03-16

As the number of people living with heart failure continues to grow, future treatments will focus on efficient donor organ donation and ensuring safe and durable outcomes. This review will focus on organ procurement, graft surveillance and emerging therapies. Preliminary studies into donation after cardiac death have indicated that this may be an effective means to increase the donor pool. Novel preservation techniques that include ex-vivo perfusion to improve donor metabolic stabilization prior to implantation may also expand the donor pool. Biomarkers, including circulating-free DNA, are emerging that could replace the endomyocardial biopsy for acute graft rejection, but we lack a risk predictive biomarker in heart transplantation. Novel immune suppressants are being investigated. Emerging therapeutics to reduce the development of chronic allograft vasculopathy are yet to be found. This review highlights the most recent studies and future possible therapies that will improve outcomes in cardiac transplantation. Larger clinical trials are currently taking place and will be needed in the future to develop and sustain current trends toward better survival rates with cardiac transplantation.

Strategy for the management of uncomplicated retinal detachments: the European vitreo-retinal society retinal detachment study report 1.

PubMed

Adelman, Ron A; Parnes, Aaron J; Ducournau, Didier

2013-09-01

To study success and failure in the treatment of uncomplicated rhegmatogenous retinal detachments (RRDs). Nonrandomized, multicenter retrospective study. One hundred seventy-six surgeons from 48 countries spanning 5 continents provided information on the primary procedures for 7678 cases of RRDs including 4179 patients with uncomplicated RRDs. Reported data included specific clinical findings, the method of repair, and the outcome after intervention. Final failure of retinal detachment repair (level 1 failure rate), remaining silicone oil at the study's conclusion (level 2 failure rate), and need for additional procedures to repair the detachment (level 3 failure rate). Four thousand one hundred seventy-nine uncomplicated cases of RRD were included. Combining phakic, pseudophakic, and aphakic groups, those treated with scleral buckle alone (n = 1341) had a significantly lower final failure rate than those treated with vitrectomy, with or without a supplemental buckle (n = 2723; P = 0.04). In phakic patients, final failure rate was lower in the scleral buckle group compared with those who had vitrectomy, with or without a supplemental buckle (P = 0.028). In pseudophakic patients, the failure rate of the initial procedure was lower in the vitrectomy group compared with the scleral buckle group (P = 3×10(-8)). There was no statistically significant difference in failure rate between segmental (n = 721) and encircling (n = 351) buckles (P = 0.5). Those who underwent vitrectomy with a supplemental scleral buckle (n = 488) had an increased failure rate compared with those who underwent vitrectomy alone (n = 2235; P = 0.048). Pneumatic retinopexy was found to be comparable with scleral buckle when a retinal hole was present (P = 0.65), but not in cases with a flap tear (P = 0.034). In the treatment of uncomplicated phakic retinal detachments, repair using scleral buckle may be a good option. There was no significant difference between segmental versus 360-degree buckle. For pseudophakic uncomplicated retinal detachments, the surgeon should balance the risks and benefits of vitrectomy versus scleral buckle and keep in mind that the single-surgery reattachment rate may be higher with vitrectomy. However, if a vitrectomy is to be performed, these data suggest that a supplemental buckle is not helpful. The author(s) have no proprietary or commercial interest in any materials discussed in this article. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Estimation of probability of failure for damage-tolerant aerospace structures

NASA Astrophysics Data System (ADS)

Halbert, Keith

The majority of aircraft structures are designed to be damage-tolerant such that safe operation can continue in the presence of minor damage. It is necessary to schedule inspections so that minor damage can be found and repaired. It is generally not possible to perform structural inspections prior to every flight. The scheduling is traditionally accomplished through a deterministic set of methods referred to as Damage Tolerance Analysis (DTA). DTA has proven to produce safe aircraft but does not provide estimates of the probability of failure of future flights or the probability of repair of future inspections. Without these estimates maintenance costs cannot be accurately predicted. Also, estimation of failure probabilities is now a regulatory requirement for some aircraft. The set of methods concerned with the probabilistic formulation of this problem are collectively referred to as Probabilistic Damage Tolerance Analysis (PDTA). The goal of PDTA is to control the failure probability while holding maintenance costs to a reasonable level. This work focuses specifically on PDTA for fatigue cracking of metallic aircraft structures. The growth of a crack (or cracks) must be modeled using all available data and engineering knowledge. The length of a crack can be assessed only indirectly through evidence such as non-destructive inspection results, failures or lack of failures, and the observed severity of usage of the structure. The current set of industry PDTA tools are lacking in several ways: they may in some cases yield poor estimates of failure probabilities, they cannot realistically represent the variety of possible failure and maintenance scenarios, and they do not allow for model updates which incorporate observed evidence. A PDTA modeling methodology must be flexible enough to estimate accurately the failure and repair probabilities under a variety of maintenance scenarios, and be capable of incorporating observed evidence as it becomes available. This dissertation describes and develops new PDTA methodologies that directly address the deficiencies of the currently used tools. The new methods are implemented as a free, publicly licensed and open source R software package that can be downloaded from the Comprehensive R Archive Network. The tools consist of two main components. First, an explicit (and expensive) Monte Carlo approach is presented which simulates the life of an aircraft structural component flight-by-flight. This straightforward MC routine can be used to provide defensible estimates of the failure probabilities for future flights and repair probabilities for future inspections under a variety of failure and maintenance scenarios. This routine is intended to provide baseline estimates against which to compare the results of other, more efficient approaches. Second, an original approach is described which models the fatigue process and future scheduled inspections as a hidden Markov model. This model is solved using a particle-based approximation and the sequential importance sampling algorithm, which provides an efficient solution to the PDTA problem. Sequential importance sampling is an extension of importance sampling to a Markov process, allowing for efficient Bayesian updating of model parameters. This model updating capability, the benefit of which is demonstrated, is lacking in other PDTA approaches. The results of this approach are shown to agree with the results of the explicit Monte Carlo routine for a number of PDTA problems. Extensions to the typical PDTA problem, which cannot be solved using currently available tools, are presented and solved in this work. These extensions include incorporating observed evidence (such as non-destructive inspection results), more realistic treatment of possible future repairs, and the modeling of failure involving more than one crack (the so-called continuing damage problem). The described hidden Markov model / sequential importance sampling approach to PDTA has the potential to improve aerospace structural safety and reduce maintenance costs by providing a more accurate assessment of the risk of failure and the likelihood of repairs throughout the life of an aircraft.

Validity testing and neuropsychology practice in the VA healthcare system: results from recent practitioner survey (.).

PubMed

Young, J Christopher; Roper, Brad L; Arentsen, Timothy J

2016-05-01

A survey of neuropsychologists in the Veterans Health Administration examined symptom/performance validity test (SPVT) practices and estimated base rates for patient response bias. Invitations were emailed to 387 psychologists employed within the Veterans Affairs (VA), identified as likely practicing neuropsychologists, resulting in 172 respondents (44.4% response rate). Practice areas varied, with 72% at least partially practicing in general neuropsychology clinics and 43% conducting VA disability exams. Mean estimated failure rates were 23.0% for clinical outpatient, 12.9% for inpatient, and 39.4% for disability exams. Failure rates were the highest for mTBI and PTSD referrals. Failure rates were positively correlated with the number of cases seen and frequency and number of SPVT use. Respondents disagreed regarding whether one (45%) or two (47%) failures are required to establish patient response bias, with those administering more measures employing the more stringent criterion. Frequency of the use of specific SPVTs is reported. Base rate estimates for SPVT failure in VA disability exams are comparable to those in other medicolegal settings. However, failure in routine clinical exams is much higher in the VA than in other settings, possibly reflecting the hybrid nature of the VA's role in both healthcare and disability determination. Generally speaking, VA neuropsychologists use SPVTs frequently and eschew pejorative terms to describe their failure. Practitioners who require only one SPVT failure to establish response bias may overclassify patients. Those who use few or no SPVTs may fail to identify response bias. Additional clinical and theoretical implications are discussed.

Heart failure as a general pandemic in Asia.

PubMed

Shimokawa, Hiroaki; Miura, Masanobu; Nochioka, Kotaro; Sakata, Yasuhiko

2015-09-01

Heart failure (HF) is an epidemic in healthcare worldwide, including Asia. It appears that HF will become more serious in the near future, with the epidemiological transition and ageing of the population. However, in contrast to Western countries, information on HF epidemiology is still limited in Asia, particularly in South Asia. In this review, we will briefly summarize available information regarding the current and future burden of HF in Asia, which indicates the importance of both primary prevention of underlying diseases of HF and secondary prevention, including management of ischaemic HF, HF with preserved EF, and HF in the elderly. © 2015 The Authors European Journal of Heart Failure © 2015 European Society of Cardiology.

Scoping review: Hospital nursing factors associated with 30-day readmission rates of patients with heart failure.

PubMed

Jun, Jin; Faulkner, Kenneth M

2018-04-01

To review the current literature on hospital nursing factors associated with 30-day readmission rates of patients with heart failure. Heart failure is a common, yet debilitating chronic illness with high mortality and morbidity. One in five patients with heart failure will experience unplanned readmission to a hospital within 30 days. Given the significance of heart failure to individuals, families and healthcare system, the Center for Medicare and Medicaid Services has made reducing 30-day readmission rates a priority. Scoping review, which maps the key concepts of a research area, is used. Published primary studies in English assessing factors related to nurses in hospitals and readmission of patients with heart failure were included. Other inclusion criteria were written in English and published in peer-reviewed journals. The search resulted in 2,782 articles. After removing duplicates and reviewing the inclusion and exclusion criteria, five articles were selected. Three nursing workforce factors emerged as follows: (i) nursing staffing, (ii) nursing care and work environment, and (iii) nurses' knowledge of heart failure. This is the first scoping review examining the association between hospital nursing factors and 30-day readmission rates of patients with heart failure. Further studies examining the extent of nursing structural and process factors influencing the outcomes of patients with heart failure are needed. Nurses are an integral part of the healthcare system. Identifying the factors related to nurses in hospitals is important to ensure comprehensive delivery of care to the chronically ill population. Hospital administrators, managers and policymakers can use the findings from this review to implement strategies to reduce 30-day readmission rates of patients with heart failure. © 2018 John Wiley & Sons Ltd.

Comparative study of the failure rates among 3 implantable defibrillator leads.

PubMed

van Malderen, Sophie C H; Szili-Torok, Tamas; Yap, Sing C; Hoeks, Sanne E; Zijlstra, Felix; Theuns, Dominic A M J

2016-12-01

After the introduction of the Biotronik Linox S/SD high-voltage lead, several cases of early failure have been observed. The purpose of this article was to assess the performance of the Linox S/SD lead in comparison to 2 other contemporary leads. We used the prospective Erasmus MC ICD registry to identify all implanted Linox S/SD (n = 408), Durata (St. Jude Medical, model 7122) (n = 340), and Endotak Reliance (Boston Scientific, models 0155, 0138, and 0158) (n = 343) leads. Lead failure was defined by low- or high-voltage impedance, failure to capture, sense or defibrillate, or the presence of nonphysiological signals not due to external interference. During a median follow-up of 5.1 years, 24 Linox (5.9%), 5 Endotak (1.5%), and 5 Durata (1.5%) leads failed. At 5-year follow-up, the cumulative failure rate of Linox leads (6.4%) was higher than that of Endotak (0.4%; P < .0001) and Durata (2.0%; P = .003) leads. The incidence rate was higher in Linox leads (1.3 per 100 patient-years) than in Endotak and Durata leads (0.2 and 0.3 per 100 patient-years, respectively; P < .001). A log-log analysis of the cumulative hazard for Linox leads functioning at 3-year follow-up revealed a stable failure rate of 3% per year. The majority of failures consisted of noise (62.5%) and abnormal impedance (33.3%). This study demonstrates a higher failure rate of Linox S/SD high-voltage leads compared to contemporary leads. Although the mechanism of lead failure is unclear, the majority presents with abnormal electrical parameters. Comprehensive monitoring of Linox S/SD high-voltage leads includes remote monitoring to facilitate early detection of lead failure. Copyright © 2016. Published by Elsevier Inc.

A real-time diagnostic and performance monitor for UNIX. M.S. Thesis

NASA Technical Reports Server (NTRS)

Dong, Hongchao

1992-01-01

There are now over one million UNIX sites and the pace at which new installations are added is steadily increasing. Along with this increase, comes a need to develop simple efficient, effective and adaptable ways of simultaneously collecting real-time diagnostic and performance data. This need exists because distributed systems can give rise to complex failure situations that are often un-identifiable with single-machine diagnostic software. The simultaneous collection of error and performance data is also important for research in failure prediction and error/performance studies. This paper introduces a portable method to concurrently collect real-time diagnostic and performance data on a distributed UNIX system. The combined diagnostic/performance data collection is implemented on a distributed multi-computer system using SUN4's as servers. The approach uses existing UNIX system facilities to gather system dependability information such as error and crash reports. In addition, performance data such as CPU utilization, disk usage, I/O transfer rate and network contention is also collected. In the future, the collected data will be used to identify dependability bottlenecks and to analyze the impact of failures on system performance.

Assessment of follicle viability using fluorescence microscopy before and after ovarian thawing.

PubMed

Sofoudis, C; Zervomanolakis, I; Galani, I; Grigoriou, V; Botsis, D; Vlahos, N

2017-01-01

The incidence of young women diagnosed with cancer has been globally increasing. In many cases the surgical approach followed by chemotherapy, radiotherapy or hormonal therapy could lead to infertility or premature ovarian failure. Several options are available in order to preserve fertility and increase the future gestation rate. Among embryo cryopreservation and oocyte cryopreservation, ovarian tissue cryopreservation represents an ideal option, especially for premenopausal women and for those who cannot delay the start of chemotherapy. The purpose of this study was to examine the follicle viability using fluorescence microscope before and after ovarian thawing.

Results of instrument reliability study for high-level nuclear-waste repositories. [Geotechnical parameters

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

Rogue, F.; Binnall, E.P.

1982-10-01

Reliable instrumentation will be needed to monitor the performance of future high-level waste repository sites. A study has been made to assess instrument reliability at Department of Energy (DOE) waste repository related experiments. Though the study covers a wide variety of instrumentation, this paper concentrates on experiences with geotechnical instrumentation in hostile repository-type environments. Manufacturers have made some changes to improve the reliability of instruments for repositories. This paper reviews the failure modes, rates, and mechanisms, along with manufacturer modifications and recommendations for additional improvements to enhance instrument performance. 4 tables.

An accelerated test design for use with synchronous orbit. [on Ni-Cd cell degradation behavior

NASA Technical Reports Server (NTRS)

Mcdermott, P. P.; Vasanth, K. L.

1980-01-01

The Naval Weapons Support Center at Crane, Indiana has conducted a large scale accelerated test of 6.0 Ah Ni-Cd cells. Data from the Crane test have been used to develop an equation for the description of Ni-Cd cell behavior in geosynchronous orbit. This equation relates the anticipated time to failure for a cell in synchronous orbit to temperature and overcharge rate sustained by the cell during the light period. A test design is suggested which uses this equation for setting test parameters for future accelerated testing.

Natural selection can favour 'irrational' behaviour.

PubMed

McNamara, J M; Trimmer, P C; Houston, A I

2014-01-01

Understanding decisions is the fundamental aim of the behavioural sciences. The theory of rational choice is based on axiomatic principles such as transitivity and independence of irrelevant alternatives (IIA). Empirical studies have demonstrated that the behaviour of humans and other animals often seems irrational; there can be a lack of transitivity in choice and seemingly irrelevant alternatives can alter decisions. These violations of transitivity and IIA undermine rational choice theory. However, we show that an individual that is maximizing its rate of food gain can exhibit failure of transitivity and IIA. We show that such violations can be caused because a current option may disappear in the near future or a better option may reappear soon. Current food options can be indicative of food availability in the near future, and this key feature can result in apparently irrational behaviour.

Tissue chips - innovative tools for drug development and disease modeling.

PubMed

Low, L A; Tagle, D A

2017-09-12

The high rate of failure during drug development is well-known, however recent advances in tissue engineering and microfabrication have contributed to the development of microphysiological systems (MPS), or 'organs-on-chips' that recapitulate the function of human organs. These 'tissue chips' could be utilized for drug screening and safety testing to potentially transform the early stages of the drug development process. They can also be used to model disease states, providing new tools for the understanding of disease mechanisms and pathologies, and assessing effectiveness of new therapies. In the future, they could be used to test new treatments and therapeutics in populations - via clinical trials-on-chips - and individuals, paving the way for precision medicine. Here we will discuss the wide-ranging and promising future of tissue chips, as well as challenges facing their development.

Failure factors in non-life insurance companies in United Kingdom

NASA Astrophysics Data System (ADS)

Samsudin, Humaida Banu

2013-04-01

Failure in insurance company is a condition of financial distress where a company has difficulty paying off its financial obligations to its creditors. This study continues the research from the study in identifying the determinants for run-off non-life insurance companies in United Kingdom. The analysis continues to identify other variables that could lead companies to financial distress that is macroeconomic factors (GDP rates, inflation rates and interest rates); total companies failed a year before and average size for failed companies'. The result from the analysis indicates that inflation rates, interest rates, total companies failed a year before and average sizes for failed companies are the best predictors. An early detection of failure can prevent companies from bankruptcy and allow management to take action to reduce the failure costs.

Early neurodevelopmental outcomes of infants with intestinal failure.

PubMed

So, Stephanie; Patterson, Catherine; Gold, Anna; Rogers, Alaine; Kosar, Christina; de Silva, Nicole; Burghardt, Karolina Maria; Avitzur, Yaron; Wales, Paul W

2016-10-01

The survival rate of infants and children with intestinal failure is increasing, necessitating a greater focus on their developmental trajectory. To evaluate neurodevelopmental outcomes in children with intestinal failure at 0-15months corrected age. Analysis of clinical, demographic and developmental assessment results of 33 children followed in an intestinal rehabilitation program between 2011 and 2014. Outcome measures included: Prechtl's Assessment of General Movements, Movement Assessment of Infants, Alberta Infant Motor Scale and Mullen Scales of Early Learning. Clinical factors were correlated with poorer developmental outcomes at 12-15months corrected age. Thirty-three infants (17 males), median gestational age 34weeks (interquartile range 29.5-36.0) with birth weight 1.98kg (interquartile range 1.17-2.50). Twenty-nine (88%) infants had abnormal General Movements. More than half had suspect or abnormal scores on the Alberta Infant Motor Scale and medium to high-risk scores for future neuromotor delay on the Movement Assessment of Infants. Delays were seen across all Mullen subscales, most notably in gross motor skills. Factors significantly associated with poorer outcomes at 12-15months included: prematurity, low birth weight, central nervous system co-morbidity, longer neonatal intensive care admission, necrotizing enterocolitis diagnosis, number of operations and conjugated hyperbilirubinemia. Multiple risk factors contribute to early developmental delay in children with intestinal failure, highlighting the importance of close developmental follow-up. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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

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

Varlotto, John M., E-mail: jvarlotto@hmc.psu.edu; Medford-Davis, Laura Nyshel; Recht, Abram

2011-10-01

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

Effects of Self-Graphing and Goal Setting on the Math Fact Fluency of Students with Disabilities

PubMed Central

Figarola, Patricia M; Gunter, Philip L; Reffel, Julia M; Worth, Susan R; Hummel, John; Gerber, Brian L

2008-01-01

We evaluated the impact of goal setting and students' participation in graphing their own performance data on the rate of math fact calculations. Participants were 3 students with mild disabilities in the first and second grades; 2 of the 3 students were also identified with Attention-Deficit/Hyperactivity Disorder (ADHD). They were taught to use Microsoft Excel® software to graph their rate of correct calculations when completing timed, independent practice sheets consisting of single-digit mathematics problems. Two students' rates of correct calculations nearly always met or exceeded the aim line established for their correct calculations. Additional interventions were required for the third student. Results are discussed in terms of implications and future directions for increasing the use of evaluation components in classrooms for students at risk for behavior disorders and academic failure. PMID:22477686

NASA trend analysis procedures

NASA Technical Reports Server (NTRS)

1993-01-01

This publication is primarily intended for use by NASA personnel engaged in managing or implementing trend analysis programs. 'Trend analysis' refers to the observation of current activity in the context of the past in order to infer the expected level of future activity. NASA trend analysis was divided into 5 categories: problem, performance, supportability, programmatic, and reliability. Problem trend analysis uncovers multiple occurrences of historical hardware or software problems or failures in order to focus future corrective action. Performance trend analysis observes changing levels of real-time or historical flight vehicle performance parameters such as temperatures, pressures, and flow rates as compared to specification or 'safe' limits. Supportability trend analysis assesses the adequacy of the spaceflight logistics system; example indicators are repair-turn-around time and parts stockage levels. Programmatic trend analysis uses quantitative indicators to evaluate the 'health' of NASA programs of all types. Finally, reliability trend analysis attempts to evaluate the growth of system reliability based on a decreasing rate of occurrence of hardware problems over time. Procedures for conducting all five types of trend analysis are provided in this publication, prepared through the joint efforts of the NASA Trend Analysis Working Group.

Profile and professional expectations of medical students in Mozambique: a longitudinal study.

PubMed

Ferrinho, Paulo; Fronteira, Inês; Sidat, Mohsin; da Sousa, Fernando; Dussault, Gilles

2010-09-21

This paper compares the socioeconomic profile of medical students registered at the Faculty of Medicine of Universidade Eduardo Mondlane (FM-UEM), Maputo, for the years 1998/99 and 2007/08. The objective is to describe the medical students' social and geographical origins, expectations and perceived difficulties regarding their education and professional future. Data were collected through questionnaires administered to all medical students. The response rate in 1998/99 was 51% (227/441) and 50% in 2007/08 (484/968).The main results reflect a doubling of the number of students enrolled for medical studies at the FM-UEM, associated with improved student performance (as reflected by failure rates). Nevertheless, satisfaction with the training received remains low and, now as before, students still identify lack of access to books or learning technology and inadequate teacher preparedness as major problems. There is a high level of commitment to public sector service. However, students, as future doctors, have very high salary expectations that will not be met by current public sector salary scales. This is reflected in an increasing degree of orientation to double sector employment after graduation.

Cardiovascular risks associated with abacavir and tenofovir exposure in HIV-infected persons.

PubMed

Choi, Andy I; Vittinghoff, Eric; Deeks, Steven G; Weekley, Cristin C; Li, Yongmei; Shlipak, Michael G

2011-06-19

Abacavir use has been associated with cardiovascular risk, but it is unknown whether this association may be partly explained by patients with kidney disease being preferentially treated with abacavir to avoid tenofovir. Our objective was to compare associations of abacavir and tenofovir with cardiovascular risks in HIV-infected veterans. Cohort study of 10 931 HIV-infected patients initiating antiretroviral therapy in the Veterans Health Administration from 1997 to 2007, using proportional hazards survival regression. Primary predictors were exposure to abacavir or tenofovir within the past 6 months, compared with no exposure to these drugs, respectively. Outcomes were time to first atherosclerotic cardiovascular event, defined as coronary, cerebrovascular, or peripheral arterial disease; and time to incident heart failure. Over 60 588 person-years of observation, there were 501 cardiovascular and 194 heart failure events. Age-standardized event rates among abacavir and tenofovir users were 12.5 versus 8.2 per 1000 person-years for cardiovascular disease, and 3.9 and 3.7 per 1000 person-years for heart failure, respectively. In multivariate-adjusted models, including time-updated measurements of kidney function, recent abacavir use was significantly associated with incident cardiovascular disease [hazard ratio 1.48, 95% confidence interval (CI) 1.08-2.04]; the association was similar but nonsignificant for heart failure (1.45, 0.85-2.47). In contrast, recent tenofovir use was significantly associated with heart failure (1.82, 1.02-3.24), but not with cardiovascular events (0.78, 0.52-1.16). Recent abacavir exposure was independently associated with increased risk for cardiovascular events. We also observed an association between recent tenofovir exposure and heart failure, which needs to be confirmed in future studies.

Cardiovascular risks associated with abacavir and tenofovir exposure in HIV-infected persons

PubMed Central

Choi, Andy I.; Vittinghoff, Eric; Deeks, Steven G.; Weekley, Cristin C.; Li, Yongmei; Shlipak, Michael G.

2014-01-01

Objective Abacavir use has been associated with cardiovascular risk, but it is unknown whether this association may be partly explained by patients with kidney disease being preferentially treated with abacavir to avoid tenofovir. Our objective was to compare associations of abacavir and tenofovir with cardiovascular risks in HIV-infected veterans. Design Cohort study of 10 931 HIV-infected patients initiating antiretroviral therapy in the Veterans Health Administration from 1997 to 2007, using proportional hazards survival regression. Methods Primary predictors were exposure to abacavir or tenofovir within the past 6 months, compared with no exposure to these drugs, respectively. Outcomes were time to first atherosclerotic cardiovascular event, defined as coronary, cerebrovascular, or peripheral arterial disease; and time to incident heart failure. Results Over 60 588 person-years of observation, there were 501 cardiovascular and 194 heart failure events. Age-standardized event rates among abacavir and tenofovir users were 12.5 versus 8.2 per 1000 person-years for cardiovascular disease, and 3.9 and 3.7 per 1000 person-years for heart failure, respectively. In multivariate-adjusted models, including time-updated measurements of kidney function, recent abacavir use was significantly associated with incident cardiovascular disease [hazard ratio 1.48, 95% confidence interval (CI) 1.08–2.04]; the association was similar but nonsignificant for heart failure (1.45, 0.85–2.47). In contrast, recent tenofovir use was significantly associated with heart failure (1.82, 1.02–3.24), but not with cardiovascular events (0.78, 0.52–1.16). Conclusion Recent abacavir exposure was independently associated with increased risk for cardiovascular events. We also observed an association between recent tenofovir exposure and heart failure, which needs to be confirmed in future studies. PMID:21516027

A Decreasing Failure Rate, Mixed Exponential Model Applied to Reliability.

DTIC Science & Technology

1981-06-01

Trident missile systems have been observed. The mixed exponential distribu- tion has been shown to fit the life data for the electronic equipment on...these systems . This paper discusses some of the estimation problems which occur with the decreasing failure rate mixed exponential distribution when...assumption of constant or increasing failure rate seemed to be incorrect. 2. However, the design of this electronic equipment indicated that

High-Strain Rate Failure Modeling Incorporating Shear Banding and Fracture

DTIC Science & Technology

2017-11-22

High Strain Rate Failure Modeling Incorporating Shear Banding and Fracture The views, opinions and/or findings contained in this report are those of...SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6. AUTHORS...Report as of 05-Dec-2017 Agreement Number: W911NF-13-1-0238 Organization: Columbia University Title: High Strain Rate Failure Modeling Incorporating

Mechanistic Considerations Used in the Development of the PROFIT PCI Failure Model

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

Pankaskie, P. J.

A fuel Pellet-Zircaloy Cladding (thermo-mechanical-chemical) Interactions (PC!) failure model for estimating the probability of failure in !ransient increases in power (PROFIT) was developed. PROFIT is based on 1) standard statistical methods applied to available PC! fuel failure data and 2) a mechanistic analysis of the environmental and strain-rate-dependent stress versus strain characteristics of Zircaloy cladding. The statistical analysis of fuel failures attributable to PCI suggested that parameters in addition to power, transient increase in power, and burnup are needed to define PCI fuel failures in terms of probability estimates with known confidence limits. The PROFIT model, therefore, introduces an environmentalmore » and strain-rate dependent strain energy absorption to failure (SEAF) concept to account for the stress versus strain anomalies attributable to interstitial-disloction interaction effects in the Zircaloy cladding. Assuming that the power ramping rate is the operating corollary of strain-rate in the Zircaloy cladding, then the variables of first order importance in the PCI fuel failure phenomenon are postulated to be: 1. pre-transient fuel rod power, P{sub I}, 2. transient increase in fuel rod power, {Delta}P, 3. fuel burnup, Bu, and 4. the constitutive material property of the Zircaloy cladding, SEAF.« less

Factors Predicting Meniscal Allograft Transplantation Failure

PubMed Central

Parkinson, Ben; Smith, Nicholas; Asplin, Laura; Thompson, Peter; Spalding, Tim

2016-01-01

Background: Meniscal allograft transplantation (MAT) is performed to improve symptoms and function in patients with a meniscal-deficient compartment of the knee. Numerous studies have shown a consistent improvement in patient-reported outcomes, but high failure rates have been reported by some studies. The typical patients undergoing MAT often have multiple other pathologies that require treatment at the time of surgery. The factors that predict failure of a meniscal allograft within this complex patient group are not clearly defined. Purpose: To determine predictors of MAT failure in a large series to refine the indications for surgery and better inform future patients. Study Design: Cohort study; Level of evidence, 3. Methods: All patients undergoing MAT at a single institution between May 2005 and May 2014 with a minimum of 1-year follow-up were prospectively evaluated and included in this study. Failure was defined as removal of the allograft, revision transplantation, or conversion to a joint replacement. Patients were grouped according to the articular cartilage status at the time of the index surgery: group 1, intact or partial-thickness chondral loss; group 2, full-thickness chondral loss 1 condyle; and group 3, full-thickness chondral loss both condyles. The Cox proportional hazards model was used to determine significant predictors of failure, independently of other factors. Kaplan-Meier survival curves were produced for overall survival and significant predictors of failure in the Cox proportional hazards model. Results: There were 125 consecutive MATs performed, with 1 patient lost to follow-up. The median follow-up was 3 years (range, 1-10 years). The 5-year graft survival for the entire cohort was 82% (group 1, 97%; group 2, 82%; group 3, 62%). The probability of failure in group 1 was 85% lower (95% CI, 13%-97%) than in group 3 at any time. The probability of failure with lateral allografts was 76% lower (95% CI, 16%-89%) than medial allografts at any time. Conclusion: This study showed that the presence of severe cartilage damage at the time of MAT and medial allografts were significantly predictive of failure. Surgeons and patients should use this information when considering the risks and benefits of surgery. PMID:27583257

Failure on the American Board of Surgery Examinations of General Surgery Residency Graduates Correlates Positively with States' Malpractice Risk.

PubMed

Dent, Daniel L; Al Fayyadh, Mohammed J; Rawlings, Jeremy A; Hassan, Ramy A; Kempenich, Jason W; Willis, Ross E; Stewart, Ronald M

2018-03-01

It has been suggested that in environments where there is greater fear of litigation, resident autonomy and education is compromised. Our aim was to examine failure rates on American Board of Surgery (ABS) examinations in comparison with medical malpractice payments in 47 US states/territories that have general surgery residency programs. We hypothesized higher ABS examination failure rates for general surgery residents who graduate from residencies in states with higher malpractice risk. We conducted a retrospective review of five-year (2010-2014) pass rates of first-time examinees of the ABS examinations. States' malpractice data were adjusted based on population. ABS examinations failure rates for programs in states with above and below median malpractice payments per capita were 31 and 24 per cent (P < 0.01) respectively. This difference was seen in university and independent programs regardless of size. Pearson correlation confirmed a significant positive correlation between board failure rates and malpractice payments per capita for Qualifying Examination (P < 0.02), Certifying Examination (P < 0.02), and Qualifying and Certifying combined index (P < 0.01). Malpractice risk correlates positively with graduates' failure rates on ABS examinations regardless of program size or type. We encourage further examination of training environments and their relationship to surgical residency graduate performance.

Destructive Single-Event Failures in Schottky Diodes

NASA Technical Reports Server (NTRS)

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

2014-01-01

This presentation contains test results for destructive failures in DC-DC converters. We have shown that Schottky diodes are susceptible to destructive single-event effects. Future work will be completed to identify parameter that determines diode susceptibility.

40 CFR 51.352 - Basic I/M performance standard.

Code of Federal Regulations, 2010 CFR

2010-07-01

...% emission test failure rate among pre-1981 model year vehicles. (10) Waiver rate. A 0% waiver rate. (11... 20% emission test failure rate among pre-1981 model year vehicles. (11) Waiver rate. A 0% waiver rate... Requirements § 51.352 Basic I/M performance standard. (a) Basic I/M programs shall be designed and implemented...

40 CFR 51.352 - Basic I/M performance standard.

Code of Federal Regulations, 2014 CFR

2014-07-01

...% emission test failure rate among pre-1981 model year vehicles. (10) Waiver rate. A 0% waiver rate. (11... 20% emission test failure rate among pre-1981 model year vehicles. (11) Waiver rate. A 0% waiver rate... Requirements § 51.352 Basic I/M performance standard. (a) Basic I/M programs shall be designed and implemented...

40 CFR 51.352 - Basic I/M performance standard.

Code of Federal Regulations, 2011 CFR

2011-07-01

...% emission test failure rate among pre-1981 model year vehicles. (10) Waiver rate. A 0% waiver rate. (11... 20% emission test failure rate among pre-1981 model year vehicles. (11) Waiver rate. A 0% waiver rate... Requirements § 51.352 Basic I/M performance standard. (a) Basic I/M programs shall be designed and implemented...

40 CFR 51.352 - Basic I/M performance standard.

Code of Federal Regulations, 2012 CFR

2012-07-01

...% emission test failure rate among pre-1981 model year vehicles. (10) Waiver rate. A 0% waiver rate. (11... 20% emission test failure rate among pre-1981 model year vehicles. (11) Waiver rate. A 0% waiver rate... Requirements § 51.352 Basic I/M performance standard. (a) Basic I/M programs shall be designed and implemented...

40 CFR 51.352 - Basic I/M performance standard.

Code of Federal Regulations, 2013 CFR

2013-07-01

...% emission test failure rate among pre-1981 model year vehicles. (10) Waiver rate. A 0% waiver rate. (11... 20% emission test failure rate among pre-1981 model year vehicles. (11) Waiver rate. A 0% waiver rate... Requirements § 51.352 Basic I/M performance standard. (a) Basic I/M programs shall be designed and implemented...

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 Coulomb failure model in which the failure stress threshold is lowered due to weakening, increasing the clock advance. The deviation from a non-Coulomb response also depends on the loading rate, elastic stiffness, initial conditions, and assumptions about how state evolves.

Mechanical Properties of Transgenic Silkworm Silk Under High Strain Rate Tensile Loading

NASA Astrophysics Data System (ADS)

Chu, J.-M.; Claus, B.; Chen, W.

2017-12-01

Studies have shown that transgenic silkworm silk may be capable of having similar properties of spider silk while being mass-producible. In this research, the tensile stress-strain response of transgenic silkworm silk fiber is systematically characterized using a quasi-static load frame and a tension Kolsky bar over a range of strain-rates between 10^{-3} and 700/s. The results show that transgenic silkworm silk tends to have higher overall ultimate stress and failure strain at high strain rate (700/s) compared to quasi-static strain rates, indicating rate sensitivity of the material. The failure strain at the high strain rate is higher than that of spider silk. However, the stress levels are significantly below that of spider silk, and far below that of high-performance fiber. Failure surfaces are examined via scanning electron microscopy and reveal that the failure modes are similar to those of spider silk.

Vocal fold tissue failure: preliminary data and constitutive modeling.

PubMed

Chan, Roger W; Siegmund, Thomas

2004-08-01

In human voice production (phonation), linear small-amplitude vocal fold oscillation occurs only under restricted conditions. Physiologically, phonation more often involves large-amplitude oscillation associated with tissue stresses and strains beyond their linear viscoelastic limits, particularly in the lamina propria extracellular matrix (ECM). This study reports some preliminary measurements of tissue deformation and failure response of the vocal fold ECM under large-strain shear The primary goal was to formulate and test a novel constitutive model for vocal fold tissue failure, based on a standard-linear cohesive-zone (SL-CZ) approach. Tissue specimens of the sheep vocal fold mucosa were subjected to torsional deformation in vitro, at constant strain rates corresponding to twist rates of 0.01, 0.1, and 1.0 rad/s. The vocal fold ECM demonstrated nonlinear stress-strain and rate-dependent failure response with a failure strain as low as 0.40 rad. A finite-element implementation of the SL-CZ model was capable of capturing the rate dependence in these preliminary data, demonstrating the model's potential for describing tissue failure. Further studies with additional tissue specimens and model improvements are needed to better understand vocal fold tissue failure.

Characteristics of Male and Female Students Who Experienced Success or Failure in Their First College Science Course.

ERIC Educational Resources Information Center

DeBoer, George E.

1985-01-01

Examined personality (persistence, future orientation, and the tendency toward reckless/rash behavior) and cognitive factors related to success or failure in college science courses. One finding noted is that both men and women were more apt to attribute their success to effort/ability, and their failure to the difficulty of a task. (JN)

Can Failure Succeed? Using Racial Subgroup Rules to Analyze the Effect of School Accountability Failure on Student Performance

ERIC Educational Resources Information Center

Sims, David P.

2013-01-01

Many school accountability programs are built on the premise that the sanctions attached to failure will produce higher future student achievement. Furthermore, such programs often include subgroup achievement rules that attempt to hold schools accountable for the performance of all demographic classes of students. This paper looks at two issues:…

Resilience Design Patterns - A Structured Approach to Resilience at Extreme Scale (version 1.1)

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

Hukerikar, Saurabh; Engelmann, Christian

Reliability is a serious concern for future extreme-scale high-performance computing (HPC) systems. Projections based on the current generation of HPC systems and technology roadmaps suggest the prevalence of very high fault rates in future systems. The errors resulting from these faults will propagate and generate various kinds of failures, which may result in outcomes ranging from result corruptions to catastrophic application crashes. Therefore the resilience challenge for extreme-scale HPC systems requires management of various hardware and software technologies that are capable of handling a broad set of fault models at accelerated fault rates. Also, due to practical limits on powermore » consumption in HPC systems future systems are likely to embrace innovative architectures, increasing the levels of hardware and software complexities. As a result the techniques that seek to improve resilience must navigate the complex trade-off space between resilience and the overheads to power consumption and performance. While the HPC community has developed various resilience solutions, application-level techniques as well as system-based solutions, the solution space of HPC resilience techniques remains fragmented. There are no formal methods and metrics to investigate and evaluate resilience holistically in HPC systems that consider impact scope, handling coverage, and performance & power efficiency across the system stack. Additionally, few of the current approaches are portable to newer architectures and software environments that will be deployed on future systems. In this document, we develop a structured approach to the management of HPC resilience using the concept of resilience-based design patterns. A design pattern is a general repeatable solution to a commonly occurring problem. We identify the commonly occurring problems and solutions used to deal with faults, errors and failures in HPC systems. Each established solution is described in the form of a pattern that addresses concrete problems in the design of resilient systems. The complete catalog of resilience design patterns provides designers with reusable design elements. We also define a framework that enhances a designer's understanding of the important constraints and opportunities for the design patterns to be implemented and deployed at various layers of the system stack. This design framework may be used to establish mechanisms and interfaces to coordinate flexible fault management across hardware and software components. The framework also supports optimization of the cost-benefit trade-offs among performance, resilience, and power consumption. The overall goal of this work is to enable a systematic methodology for the design and evaluation of resilience technologies in extreme-scale HPC systems that keep scientific applications running to a correct solution in a timely and cost-efficient manner in spite of frequent faults, errors, and failures of various types.« less

Failure to Rescue, Rescue Surgery and Centralization of Postoperative Complications: A Challenge for General and Acute Care Surgeons.

PubMed

Zago, Mauro; Bozzo, Samantha; Carrara, Giulia; Mariani, Diego

2017-01-01

To explore the current literature on the failure to rescue and rescue surgery concepts, to identify the key items for decreasing the failure to rescue rate and improve outcome, to verify if there is a rationale for centralization of patients suffering postoperative complications. There is a growing awareness about the need to assess and measure the failure to rescue rate, on institutional, regional and national basis. Many factors affect failure to rescue, and all should be individually analyzed and considered. Rescue surgery is one of these factors. Rescue surgery assumes an acute care surgery background. Measurement of failure to rescue rate should become a standard for quality improvement programs. Implementation of all clinical and organizational items involved is the key for better outcomes. Preparedness for rescue surgery is a main pillar in this process. Centralization of management, audit, and communication are important as much as patient centralization. Celsius.

Failure Rates of Orthodontic Fixed Lingual Retainers bonded with Two Flowable Light-cured Adhesives: A Comparative Prospective Clinical Trial.

PubMed

Talic, Nabeel F

2016-08-01

This comparative prospective randomized clinical trial examined the in vivo failure rates of fixed mandibular and maxillary lingual retainers bonded with two light-cured flowable composites over 6 months. Consecutive patients were divided into two groups on a 1:1 basis. Two hundred fixed lingual retainers were included, and their failures were followed for 6 months. One group (n = 50) received retainers bonded with a nano-hybrid composite based on nano-optimized technology (Tetric-N-Flow, Ivoclar Vivadent). Another group (n = 50) received retainers bonded with a low viscosity (LV) composite (Transbond Supreme LV, 3M Unitek). There was no significant difference between the overall failure rates of mandibular retainers bonded with Transbond (8%) and those bonded with Tetric-N-Flow (18%). However, the odds ratio for failure using Tetric-N-flow was 2.52-fold greater than that of Transbond. The failure rate of maxillary retainers bonded with Transbond was higher (14%), but not significantly different, than that of maxillary retainers bonded with Tetric-N-flow (10%). There was no significant difference in the estimated mean survival times of the maxillary and mandibular retainers bonded with the two composites. Both types of composites tested in the current study can be used to bond fixed maxillary and mandibular lingual retainers, with low failure rates.

Tunable actuation of dielectric elastomer by electromechanical loading rates

NASA Astrophysics Data System (ADS)

Li, Guorui; Zhang, Mingqi; Chen, Xiangping; Yang, Xuxu; Wong, Tuck-Whye; Li, Tiefeng; Huang, Zhilong

2017-10-01

Dielectric elastomer (DE) membranes are able to self-deform with the application of an electric field through the thickness direction. In comparison to conventional rigid counterparts, soft actuators using DE provide a variety of advantages such as high compliance, low noise, and light weight. As one of the challenges in the development of DE actuating devices, tuning the electromechanical actuating behavior is crucial in order to achieve demanded loading paths and to avoid electromechanical failures. In this paper, our experimental results show that the electromechanical loading conditions affect the actuating behaviors of the DE. The electrical actuating force can be tuned by 29.4% with the control of the electrical charging rate. In addition, controllable actuations have been investigated by the mechanical model in manipulating the electromechanical loading rate. The calculated results agree well with the experimental data. Lastly, it is believed that the mechanisms of controlling the electromechanical loading rate may serve as a guide for the design of DE devices and high performance soft robots in the near future.

Sensitivity analysis by approximation formulas - Illustrative examples. [reliability analysis of six-component architectures

NASA Technical Reports Server (NTRS)

White, A. L.

1983-01-01

This paper examines the reliability of three architectures for six components. For each architecture, the probabilities of the failure states are given by algebraic formulas involving the component fault rate, the system recovery rate, and the operating time. The dominant failure modes are identified, and the change in reliability is considered with respect to changes in fault rate, recovery rate, and operating time. The major conclusions concern the influence of system architecture on failure modes and parameter requirements. Without this knowledge, a system designer may pick an inappropriate structure.

Report of the NASA Ad Hoc Committee on failure of high strength structural materials

NASA Technical Reports Server (NTRS)

Brown, W. F., Jr. (Editor)

1972-01-01

An analysis of structural failures that have occurred in NASA programs was conducted. Reports of 231 examples of structural failure were reviewed. Attempts were made to identify those factors which contributed to the failures, and recommendations were formulated for actions which would minimize their effects on future NASA programs. Two classes of factors were identified: (1) those associated with deficiencies in existing materials and structures technology and (2) those attributable to inadequate documentation or communication of that technology.

Remote operation of an orbital maneuvering vehicle in simulated docking maneuvers

NASA Technical Reports Server (NTRS)

Brody, Adam R.

1990-01-01

Simulated docking maneuvers were performed to assess the effect of initial velocity on docking failure rate, mission duration, and delta v (fuel consumption). Subjects performed simulated docking maneuvers of an orbital maneuvering vehicle (OMV) to a space station. The effect of the removal of the range and rate displays (simulating a ranging instrumentation failure) was also examined. Naive subjects were capable of achieving a high success rate in performing simulated docking maneuvers without extensive training. Failure rate was a function of individual differences; there was no treatment effect on failure rate. The amount of time subjects reserved for final approach increased with starting velocity. Piloting of docking maneuvers was not significantly affected in any way by the removal of range and rate displays. Radial impulse was significant both by subject and by treatment. NASA's 0.1 percent rule, dictating an approach rate no greater than 0.1 percent of the range, is seen to be overly conservative for nominal docking missions.

Analysis of factors affecting failure of glass cermet tunnel restorations in a multi-center study.

PubMed

Pilebro, C E; van Dijken, J W

2001-06-01

The aim of this study was to analyze factors influencing the failures of tunnel restorations performed with a glass cermet cement (Ketac Silver). Caries activity, lesion size, tunnel cavity opening size, partial or total tunnel, composite lamination or operating time showed no significant correlation to failure rate. Twelve dentists in eight clinics clinically experienced and familiar with the tunnel technique placed 374 restorations. The occlusal sections of fifty percent of the restorations were laminated with hybrid resin composite. The results of the yearly clinical and radiographic evaluations over the course of 3 years were correlated to factors that could influence the failure rate using logistic regression analysis. At the 3-year recall a cumulative number of 305 restorations were available. The cumulative replacement rate was 20%. The main reasons for replacement were marginal ridge fracture (14%) and dentin caries (3%). Another 7% of the restorations which had not been replaced were classified as failures because of untreated dentin caries. The only significant variable observed was the individual failure rate of the participating dentists varying between 9 and 50% (p=0.013).

Increase in hospital admission rates for heart failure in The Netherlands, 1980-1993.

PubMed Central

Reitsma, J. B.; Mosterd, A.; de Craen, A. J.; Koster, R. W.; van Capelle, F. J.; Grobbee, D. E.; Tijssen, J. G.

1996-01-01

OBJECTIVE: To study the trend in hospital admission rates for heart failure in the Netherlands from 1980 to 1993. DESIGN: All hospital admissions in the Netherlands with a principal discharge diagnosis of heart failure were analysed. In addition, individual records of heart failure patients from a subset of 7 hospitals were analysed to estimate the frequency and timing of readmissions. RESULTS: The total number of discharges for men increased from 7377 in 1980 to 13 022 in 1993, and for women from 7064 to 12 944. From 1980 through 1993 age adjusted discharge rates rose 48% for men and 40% for women. Age adjusted in-hospital mortality for heart failure decreased from 19% in 1980 to 15% in 1993. For all age groups in-hospital mortality for men was higher than for women. The mean length of hospital admissions in 1993 was 14.0 days for men and 16.4 days for women. A review of individual patient records from a 6.3% sample of all hospital admissions in the Netherlands indicated that within a 2 year period 18% of the heart failure patients were admitted more than once and 5% more than twice. CONCLUSIONS: For both men and women a pronounced increase in age adjusted discharge rates for heart failure was observed in the Netherlands from 1980 to 1993. Readmissions were a prominent feature among heart failure patients. Higher survival rates after acute myocardial infarction and the longer survival of patients with heart disease, including heart failure may have contributed to the observed increase. The importance of advances in diagnostic tools and of possible changes in admission policy remain uncertain. PMID:8944582

First time description of early lead failure of the Linox Smart lead compared to other contemporary high-voltage leads.

PubMed

Weberndörfer, Vanessa; Nyffenegger, Tobias; Russi, Ian; Brinkert, Miriam; Berte, Benjamin; Toggweiler, Stefan; Kobza, Richard

2018-05-01

Early lead failure has recently been reported in ICD patients with Linox SD leads. We aimed to compare the long-term performance of the following lead model Linox Smart SD with other contemporary high-voltage leads. All patients receiving high-voltage leads at our center between November 2009 and May 2017 were retrospectively analyzed. Lead failure was defined as the occurrence of one or more of the following: non-physiological high-rate episodes, low- or high-voltage impedance anomalies, undersensing, or non-capture. In total, 220 patients were included (Linox Smart SD, n = 113; contemporary lead, n = 107). During a median follow-up of 3.8 years (IQR 1.6-5.9 years), a total of 16 (14 in Linox Smart SD and 2 in contemporary group) lead failures occurred, mostly due to non-physiological high-rate sensing or impedance abnormalities. Lead failure incidence rates per 100 person-years were 2.9 (95% CI 1.7-4.9) and 0.6 (95% CI 0.1-2.3) for Linox Smart SD compared to contemporary leads respectively. Kaplan Meier estimates of 5-year lead failure rates were 14.0% (95% CI 8.1-23.6%) and 1.3% (95% CI 0.2-8.9%), respectively (log-rank p = 0.028). Implantation of a Linox Smart SD lead increased the risk of lead failure with a hazard ratio (HR) of 4.53 (95% CI 1.03-19.95, p = 0.046) and 4.44 (95% CI 1.00-19.77, p = 0.05) in uni- and multivariable Cox models. The new Linox Smart SD lead model was associated with high failure rates and should be monitored closely to detect early signs of lead failure.

Failure to activate the in-hospital emergency team: causes and outcomes.

PubMed

Barbosa, Vera; Gomes, Ernestina; Vaz, Senio; Azevedo, Gustavo; Fernandes, Gonçalo; Ferreira, Amélia; Araujo, Rui

2016-01-01

To determine the incidence of afferent limb failure of the in-hospital Medical Emergency Team, characterizing it and comparing the mortality between the population experiencing afferent limb failure and the population not experiencing afferent limb failure. A total of 478 activations of the Medical Emergency Team of Hospital Pedro Hispano occurred from January 2013 to July 2015. A sample of 285 activations was obtained after excluding incomplete records and activations for patients with less than 6 hours of hospitalization. The sample was divided into two groups: the group experiencing afferent limb failure and the group not experiencing afferent limb failure of the Medical Emergency Team. Both populations were characterized and compared. Statistical significance was set at p ≤ 0.05. Afferent limb failure was observed in 22.1% of activations. The causal analysis revealed significant differences in Medical Emergency Team activation criteria (p = 0.003) in the group experiencing afferent limb failure, with higher rates of Medical Emergency Team activation for cardiac arrest and cardiovascular dysfunction. Regarding patient outcomes, the group experiencing afferent limb failure had higher immediate mortality rates and higher mortality rates at hospital discharge, with no significant differences. No significant differences were found for the other parameters. The incidence of cardiac arrest and the mortality rate were higher in patients experiencing failure of the afferent limb of the Medical Emergency Team. This study highlights the need for health units to invest in the training of all healthcare professionals regarding the Medical Emergency Team activation criteria and emergency medical response system operations.

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.

A Prospective One-Year Microbiologic Survey of Combined Pneumonia and Respiratory Failure.

PubMed

Fisher, Kristen; Trupka, Tracy; Micek, Scott T; Juang, Paul; Kollef, Marin H

2017-10-01

Pneumonia and respiratory failure are common problems in the intensive care unit (ICU) setting, often occurring together. The relative prevalence of pneumonia types (community acquired, hospital acquired, ventilator associated) and causative pathogens is not well described in patients with respiratory failure. This was a prospective observational cohort study conducted in the medical ICU (34 beds) of Barnes-Jewish Hospital, an academic referral center of 1,300 beds from January 2016-December 2016. All patients who were prospectively adjudicated to have respiratory failure and pneumonia (RFP) regardless of pneumonia type were classified into one of four microbiologic categories: pathogen negative, antibiotic-susceptible pathogen (according to ceftriaxone susceptibility), antibiotic-resistant pathogen, and viruses. The primary outcomes assessed were the hospital mortality rate and inappropriate initial antibiotic therapy (IIAT) for non-viral pathogens. Among 364 consecutive patients with RFP, 63 (17.3%) had organisms that were antibiotic susceptible, 104 (28.6%) had antibiotic-resistant organisms, 118 (32.4%) were pathogen negative, and 79 (21.7%) had viral infections. For these categories, IIAT occurred in 3.2%, 21.2%, 0.8%, and 0, respectively (p < 0.001). Vasopressor-requiring shock was present in 61.9%, 72.1%, 68.6%, and 67.1%, respectively (p = 0.585), and the hospital mortality rates were 27.0%, 48.1%, 31.4%, and 36.7%, respectively (p = 0.020). Multivariable logistic regression analysis identified IIAT as an independent predictor of in-hospital death (adjusted odds ratio 5.28; 95% confidence interval 2.72-10.22; p = 0.012). Male gender, increasing Acute Physiology and Chronic Health Evaluation (APACHE) II scores, greater age, and the presence of shock also predicted death. Microbiologic categorization of patients with RFP suggests that antibiotic-resistant pathogens and viruses are associated with the highest mortality rates. Vasopressor-requiring shock was common regardless of the microbiologic categorization of RFP. Future development and use of rapid diagnostics and novel therapeutics targeting specific RFP pathogens may allow more timely administration of appropriate antimicrobial therapy and enhance antibiotic stewardship practices.

Volumetric analysis and indocyanine green retention rate at 15 min as predictors of post-hepatectomy liver failure

PubMed Central

Kim, Hee Joon; Kim, Choong Young; Park, Eun Kyu; Hur, Young Hoe; Koh, Yang Seok; Kim, Hyun Jong; Cho, Chol Kyoon

2015-01-01

Objectives The actual future liver remnant (aFLR) is calculated as the ratio of remnant liver volume (RLV) to total functional liver volume (TFLV). The standardized future liver remnant (sFLR) is calculated as the ratio of RLV to standard liver volume (SLV). The aims of this study were to compare the aFLR with the sFLR and to determine criteria for safe hepatectomy using computed tomography volumetry and indocyanine green retention rate at 15 min (ICG R15). Methods Medical records and volumetric measurements were obtained retrospectively for 81 patients who underwent right hemi-hepatectomy for malignant hepatic tumours from January 2010 to November 2013. The sFLR was compared with the aFLR, and a ratio of sFLR to ICG R15 as a predictor of postoperative hepatic function was established. Results In patients without cirrhosis, the sFLR showed a stronger correlation with the total serum bilirubin level than the aFLR (R2 = 0.499 versus R2 = 0.239). Post-hepatectomy liver failure developed only in the group with an sFLR of <25%, regardless of ICG R15. In patients with cirrhosis, the aFLR and sFLR had no correlation with postoperative total serum bilirubin. An sFLR : ICG R15 ratio of >1.9 showed 66.7% sensitivity and 100% specificity. Conclusions Regardless of ICG R15, an sFLR of ≥25% in patients without cirrhosis, and an sFLR of ≥25% with an sFLR : ICG R15 ratio of >1.9 in patients with cirrhosis indicate acceptable levels of safety in major hepatectomy. PMID:24964188

Failure Investigation of Radiant Platen Superheater Tube of Thermal Power Plant Boiler

NASA Astrophysics Data System (ADS)

Ghosh, D.; Ray, S.; Mandal, A.; Roy, H.

2015-04-01

This paper highlights a case study of typical premature failure of a radiant platen superheater tube of 210 MW thermal power plant boiler. Visual examination, dimensional measurement and chemical analysis, are conducted as part of the investigations. Apart from these, metallographic analysis and fractography are also conducted to ascertain the probable cause of failure. Finally it has been concluded that the premature failure of the super heater tube can be attributed to localized creep at high temperature. The corrective actions has also been suggested to avoid this type of failure in near future.

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.

Preoperative Cholangitis and Future Liver Remnant Volume Determine the Risk of Liver Failure in Patients Undergoing Resection for Hilar Cholangiocarcinoma

PubMed Central

Aloia, Thomas A; Shindoh, Junichi; Fabio, Forchino; Amisano, Marco; Passot, Guillaume; Ferrero, Alessandro; Vauthey, Jean-Nicolas

2016-01-01

Background The highest mortality rates after liver surgery are reported in patients who undergo resection for hilar cholangiocarcinoma (HCCA). In these patients, postoperative death usually follows the development of hepatic insufficiency. We sought to determine the factors associated with postoperative hepatic insufficiency and death due to liver failure in patients undergoing hepatectomy for HCCA. Study Design This study included all consecutive patients who underwent hepatectomy with curative intent for HCCA at two centers from 1996 through 2013. Preoperative clinical and operative data were analyzed to identify independent determinants of i) hepatic insufficiency and ii) liver failure–related death. Results The study included 133 patients with right or left major (n=67) or extended (n=66) hepatectomy. Preoperative biliary drainage was performed in 98 patients and was complicated by cholangitis in 40 cases. In all these patients, cholangitis was controlled before surgery. Major (Dindo III-IV) postoperative complications occurred in 73 patients (55%), with 29 suffering from hepatic insufficiency. Fifteen patients (11%) died within 90 days after surgery, 10 of them of liver failure. On multivariate analysis, predictors of postoperative hepatic insufficiency (all p<0.05) were preoperative cholangitis (odds ratio [OR]=3.2), future liver remnant (FLR) volume <30% (OR=3.5), preoperative total bilirubin level >3 mg/dl (OR=4), and albumin level <3.5 mg/dl (OR=3.3). Only preoperative cholangitis (OR=7.5, p=.016) and FLR volume <30% (OR=7.2, p=.019) predicted postoperative liver failure–related death. Conclusions Preoperative cholangitis and insufficient FLR volume are major determinants of hepatic insufficiency and postoperative liver failure–related death. Given the association between biliary drainage and cholangitis, the preoperative approach to patients with HCCA should be optimized to minimize the risk of cholangitis. PMID:27049784

Who Must We Target Now to Minimize Future Cardiovascular Events and Total Mortality?: Lessons From the Surveillance, Prevention and Management of Diabetes Mellitus (SUPREME-DM) Cohort Study.

PubMed

Desai, Jay R; Vazquez-Benitez, Gabriela; Xu, Zhiyuan; Schroeder, Emily B; Karter, Andrew J; Steiner, John F; Nichols, Gregory A; Reynolds, Kristi; Xu, Stanley; Newton, Katherine; Pathak, Ram D; Waitzfelder, Beth; Lafata, Jennifer Elston; Butler, Melissa G; Kirchner, H Lester; Thomas, Abraham; O'Connor, Patrick J

2015-09-01

Examining trends in cardiovascular events and mortality in US health systems can guide the design of targeted clinical and public health strategies to reduce cardiovascular events and mortality rates. We conducted an observational cohort study from 2005 to 2011 among 1.25 million diabetic subjects and 1.25 million nondiabetic subjects from 11 health systems that participate in the Surveillance, Prevention and Management of Diabetes Mellitus (SUPREME-DM) DataLink. Annual rates (per 1000 person-years) of myocardial infarction/acute coronary syndrome (International Classification of Diseases-Ninth Revision, 410.0–410.91, 411.1–411.8), stroke (International Classification of Diseases-Ninth Revision, 430–432.9, 433–434.9), heart failure (International Classification of Diseases-Ninth Revision, 428–428.9), and all-cause mortality were monitored by diabetes mellitus (DM) status, age, sex, race/ethnicity, and a prior cardiovascular history. We observed significant declines in cardiovascular events and mortality rates in subjects with and without DM. However, there was substantial variation by age, sex, race/ethnicity, and prior cardiovascular history. Mortality declined from 44.7 to 27.1 (P<0.0001) for those with DM and cardiovascular disease (CVD), from 11.2 to 10.9 (P=0.03) for those with DM only, and from 18.9 to 13.0 (P<0.0001) for those with CVD only. Yet, in the [almost equal to]85% of subjects with neither DM nor CVD, overall mortality (7.0 to 6.8; P=0.10) and stroke rates (1.6–1.6; P=0.77) did not decline and heart failure rates increased (0.9–1.15; P=0.0005). To sustain improvements in myocardial infarction, stroke, heart failure, and mortality, health systems that have successfully focused on care improvement in high-risk adults with DM or CVD must broaden their improvement strategies to target lower risk adults who have not yet developed DM or CVD.

Microcircuit Device Reliability. Digital Failure Rate Data

DTIC Science & Technology

1981-01-01

Center Staff I IT Research Institute Under Contract to: Rome Air Development Center Griffiss AFB, NY 13441 fortes Ordering No. MDR- 17 biKi frbi...r ■■ ■—■ — SECURITY CLASSIFICATION Or THIS PAGE (Whin Dmlm Enlti»<l) REPORT DOCUMENTATION PAGE «EPO«TNUMBER MDR- 17 4. TITLE (md...MDR- 17 presents com- parisons between actual field experienced failure rates and MIL-HDBK-217C, Notice 1, predicted failure rates. The use of

Infraclavicular versus axillary nerve catheters: A retrospective comparison of early catheter failure rate.

PubMed

Quast, Michaela B; Sviggum, Hans P; Hanson, Andrew C; Stoike, David E; Martin, David P; Niesen, Adam D

2018-05-01

Continuous brachial plexus catheters are often used to decrease pain following elbow surgery. This investigation aimed to assess the rate of early failure of infraclavicular (IC) and axillary (AX) nerve catheters following elbow surgery. Retrospective study. Postoperative recovery unit and inpatient hospital floor. 328 patients who received IC or AX nerve catheters and underwent elbow surgery were identified by retrospective query of our institution's database. Data collected included unplanned catheter dislodgement, catheter replacement rate, postoperative pain scores, and opioid administration on postoperative day 1. Catheter failure was defined as unplanned dislodging within 24 h of placement or requirement for catheter replacement and evaluated using a covariate adjusted model. 119 IC catheters and 209 AX catheters were evaluated. There were 8 (6.7%) failed IC catheters versus 13 (6.2%) failed AX catheters. After adjusting for age, BMI, and gender there was no difference in catheter failure rate between IC and AX nerve catheters (p = 0.449). These results suggest that IC and AX nerve catheters do not differ in the rate of early catheter failure, despite differences in anatomic location and catheter placement techniques. Both techniques provided effective postoperative analgesia with median pain scores < 3/10 for patients following elbow surgery. Reasons other than rate of early catheter failure should dictate which approach is performed. Copyright © 2018. Published by Elsevier Inc.

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.

Update on the Management of High-Risk Penetrating Keratoplasty

PubMed Central

Jabbehdari, Sayena; Rafii, Alireza Baradaran; Yazdanpanah, Ghasem; Hamrah, Pedram; Holland, Edward J.; Djalilian, Ali R

2017-01-01

Purpose of review In this article, we review the indications and latest management of high-risk penetrating keratoplasty. Recent findings Despite the immune-privilege status of the cornea, immune-mediated graft rejection still remains the leading cause of corneal graft failure. This is particularly a problem in the high-risk graft recipients, namely patients with previous graft failure due to rejection and those with inflamed and vascularized corneal beds. A number of strategies including both local and systemic immunosuppression are currently used to increase the success rate of high-risk corneal grafts. Moreover, in cases of limbal stem cell deficiency, limbal stem cells transplantation is employed. Summary Corticosteroids are still the top medication for prevention and treatment in cases of corneal graft rejection. Single and combined administration of immunosuppressive agents e.g. tacrolimus, cyclosporine and mycophenolate are promising adjunctive therapies for prolonging graft survival. In the future, cellular and molecular therapies should allow us to achieve immunologic tolerance even in high-risk grafts. PMID:28959505

Modeling and analyzing cascading dynamics of the Internet based on local congestion information

NASA Astrophysics Data System (ADS)

Zhu, Qian; Nie, Jianlong; Zhu, Zhiliang; Yu, Hai; Xue, Yang

2018-06-01

Cascading failure has already become one of the vital issues in network science. By considering realistic network operational settings, we propose the congestion function to represent the congested extent of node and construct a local congestion-aware routing strategy with a tunable parameter. We investigate the cascading failures on the Internet triggered by deliberate attacks. Simulation results show that the tunable parameter has an optimal value that makes the network achieve a maximum level of robustness. The robustness of the network has a positive correlation with tolerance parameter, but it has a negative correlation with the packets generation rate. In addition, there exists a threshold of the attacking proportion of nodes that makes the network achieve the lowest robustness. Moreover, by introducing the concept of time delay for information transmission on the Internet, we found that an increase of the time delay will decrease the robustness of the network rapidly. The findings of the paper will be useful for enhancing the robustness of the Internet in the future.

Amiodarone therapy in chronic heart failure and myocardial infarction: a review of the mortality trials with special attention to STAT-CHF and the GESICA trials. Grupo de Estudio de la Sobrevida en la Insuficiencia Cardiaca en Argentina.

PubMed

Pinto, J V; Ramani, K; Neelagaru, S; Kown, M; Gheorghiade, M

1997-01-01

Amiodarone appears to reduce sudden death in patients with left ventricular dysfunction resulting from an acute MI or a primary dilated cardiomyopathy, particularly if complex ventricular arrhythmias are present. Amiodarone's beneficial effect on mortality in these patients could be unrelated to its antiarrhythmic effects. Multiple factors could account for the improvement in mortality such as the drug's antiischemic effects, neuromodulating effects, its effect on left ventricular function and on heart rate. Moreover, patients with LV dysfunction who have survived an episode of sudden death would potentially benefit from amiodarone therapy. Future trials are needed to determine the precise subsets(s) of patients who would benefit from the drug and the most efficacious dosing regimen for the drug. Based on available data, amiodarone is the only antiarrhythmic agent which has not been shown to increase mortality in patients with chronic heart failure.

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.

Patient-Clinician Communication About End-of-Life Care in Patients With Advanced Chronic Organ Failure During One Year.

PubMed

Houben, Carmen H M; Spruit, Martijn A; Schols, Jos M G A; Wouters, Emiel F M; Janssen, Daisy J A

2015-06-01

Patient-clinician communication is an important prerequisite to delivering high-quality end-of-life care. However, discussions about end-of-life care are uncommon in patients with advanced chronic organ failure. The aim was to examine the quality of end-of-life care communication during one year follow-up of patients with advanced chronic organ failure. In addition, we aimed to explore whether and to what extent quality of communication about end-of-life care changes toward the end of life and whether end-of-life care communication is related to patient-perceived quality of medical care. Clinically stable outpatients (n = 265) with advanced chronic obstructive pulmonary disease, chronic heart failure, or chronic renal failure were visited at home at baseline and four, eight, and 12 months after baseline to assess quality of end-of-life care communication (Quality of Communication questionnaire). Two years after baseline, survival status was assessed, and if patients died during the study period, a bereavement interview was done with the closest relative. One year follow-up was completed by 77.7% of the patients. Quality of end-of-life care communication was rated low at baseline and did not change over one year. Quality of end-of-life care communication was comparable for patients who completed two year follow-up and patients who died during the study. The correlation between quality of end-of-life care communication and satisfaction with medical treatment was weak. End-of-life care communication is poor in patients with chronic organ failure and does not change toward the end of life. Future studies should develop an intervention aiming at initiating high-quality end-of-life care communication between patients with advanced chronic organ failure and their clinicians. Copyright © 2015 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Predicting Quarantine Failure Rates

PubMed Central

2004-01-01

Preemptive quarantine through contact-tracing effectively controls emerging infectious diseases. Occasionally this quarantine fails, however, and infected persons are released. The probability of quarantine failure is typically estimated from disease-specific data. Here a simple, exact estimate of the failure rate is derived that does not depend on disease-specific parameters. This estimate is universally applicable to all infectious diseases. PMID:15109418

High rate of virological failure and low rate of switching to second-line treatment among adolescents and adults living with HIV on first-line ART in Myanmar, 2005-2015

PubMed Central

Harries, Anthony D.; Kumar, Ajay M. V.; Oo, Myo Minn; Kyaw, Khine Wut Yee; Win, Than; Aung, Thet Ko; Min, Aung Chan; Oo, Htun Nyunt

2017-01-01

Background The number of people living with HIV on antiretroviral treatment (ART) in Myanmar has been increasing rapidly in recent years. This study aimed to estimate rates of virological failure on first-line ART and switching to second-line ART due to treatment failure at the Integrated HIV Care program (IHC). Methods Routinely collected data of all adolescent and adult patients living with HIV who were initiated on first-line ART at IHC between 2005 and 2015 were retrospectively analyzed. The cumulative hazard of virological failure on first-line ART and switching to second-line ART were estimated. Crude and adjusted hazard ratios were calculated using the Cox regression model to identify risk factors associated with the two outcomes. Results Of 23,248 adults and adolescents, 7,888 (34%) were tested for HIV viral load. The incidence rate of virological failure among those tested was 3.2 per 100 person-years follow-up and the rate of switching to second-line ART among all patients was 1.4 per 100 person-years follow-up. Factors associated with virological failure included: being adolescent; being lost to follow-up at least once; having WHO stage 3 and 4 at ART initiation; and having taken first-line ART elsewhere before coming to IHC. Of the 1032 patients who met virological failure criteria, 762 (74%) switched to second-line ART. Conclusions We found high rates of virological failure among one third of patients in the cohort who were tested for viral load. Of those failing virologically on first-line ART, about one quarter were not switched to second-line ART. Routine viral load monitoring, especially for those identified as having a higher risk of treatment failure, should be considered in this setting to detect all patients failing on first-line ART. Strategies also need to be put in place to prevent treatment failure and to treat more of those patients who are actually failing. PMID:28182786

Is rhythm-control superior to rate-control in patients with atrial fibrillation and diastolic heart failure?

PubMed

Kong, Melissa H; Shaw, Linda K; O'Connor, Christopher; Califf, Robert M; Blazing, Michael A; Al-Khatib, Sana M

2010-07-01

Although no clinical trial data exist on the optimal management of atrial fibrillation (AF) in patients with diastolic heart failure, it has been hypothesized that rhythm-control is more advantageous than rate-control due to the dependence of these patients' left ventricular filling on atrial contraction. We aimed to determine whether patients with AF and heart failure with preserved ejection fraction (EF) survive longer with rhythm versus rate-control strategy. The Duke Cardiovascular Disease Database was queried to identify patients with EF > 50%, heart failure symptoms and AF between January 1,1995 and June 30, 2005. We compared baseline characteristics and survival of patients managed with rate- versus rhythm-control strategies. Using a 60-day landmark view, Kaplan-Meier curves were generated and results were adjusted for baseline differences using Cox proportional hazards modeling. Three hundred eighty-two patients met the inclusion criteria (285 treated with rate-control and 97 treated with rhythm-control). The 1-, 3-, and 5-year survival rates were 93.2%, 69.3%, and 56.8%, respectively in rate-controlled patients and 94.8%, 78.0%, and 59.9%, respectively in rhythm-controlled patients (P > 0.10). After adjustments for baseline differences, no significant difference in mortality was detected (hazard ratio for rhythm-control vs rate-control = 0.696, 95% CI 0.453-1.07, P = 0.098). Based on our observational data, rhythm-control seems to offer no survival advantage over rate-control in patients with heart failure and preserved EF. Randomized clinical trials are needed to verify these findings and examine the effect of each strategy on stroke risk, heart failure decompensation, and quality of life.

Limits on rock strength under high confinement

NASA Astrophysics Data System (ADS)

Renshaw, Carl E.; Schulson, Erland M.

2007-06-01

Understanding of deep earthquake source mechanisms requires knowledge of failure processes active under high confinement. Under low confinement the compressive strength of rock is well known to be limited by frictional sliding along stress-concentrating flaws. Under higher confinement strength is usually assumed limited by power-law creep associated with the movement of dislocations. In a review of existing experimental data, we find that when the confinement is high enough to suppress frictional sliding, rock strength increases as a power-law function only up to a critical normalized strain rate. Within the regime where frictional sliding is suppressed and the normalized strain rate is below the critical rate, both globally distributed ductile flow and localized brittle-like failure are observed. When frictional sliding is suppressed and the normalized strain rate is above the critical rate, failure is always localized in a brittle-like manner at a stress that is independent of the degree of confinement. Within the high-confinement, high-strain rate regime, the similarity in normalized failure strengths across a variety of rock types and minerals precludes both transformational faulting and dehydration embrittlement as strength-limiting mechanisms. The magnitude of the normalized failure strength corresponding to the transition to the high-confinement, high-strain rate regime and the observed weak dependence of failure strength on strain rate within this regime are consistent with a localized Peierls-type strength-limiting mechanism. At the highest strain rates the normalized strengths approach the theoretical limit for crystalline materials. Near-theoretical strengths have previously been observed only in nano- and micro-scale regions of materials that are effectively defect-free. Results are summarized in a new deformation mechanism map revealing that when confinement and strain rate are sufficient, strengths approaching the theoretical limit can be achieved in cm-scale sized samples of rocks rich in defects. Thus, non-frictional failure processes must be considered when interpreting rock deformation data collected under high confinement and low temperature. Further, even at higher temperatures the load-bearing ability of crustal rocks under high confinement may not be limited by a frictional process under typical geologic strain rates.

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 acceptable confidence level, was difficult but, it was likely that this type of failure will not be a 100 year event. It was noticeable to see that the majority of the EDG demand failures occurred within the main components as of 2005. The overall analysis of this study provided from percentages, indicated that it would be appropriate to make the statement that the excessive event was caused by the overall age (wear and tear) of the Emergency Diesel Generators in Nuclear Power Plants. Future Work will be to better determine the return period of the excessive event once the occurrence has happened for a second time by implementing the extreme event probability approach.

Assessing changes in failure probability of dams in a changing climate

NASA Astrophysics Data System (ADS)

Mallakpour, I.; AghaKouchak, A.; Moftakhari, H.; Ragno, E.

2017-12-01

Dams are crucial infrastructures and provide resilience against hydrometeorological extremes (e.g., droughts and floods). In 2017, California experienced series of flooding events terminating a 5-year drought, and leading to incidents such as structural failure of Oroville Dam's spillway. Because of large socioeconomic repercussions of such incidents, it is of paramount importance to evaluate dam failure risks associated with projected shifts in the streamflow regime. This becomes even more important as the current procedures for design of hydraulic structures (e.g., dams, bridges, spillways) are based on the so-called stationary assumption. Yet, changes in climate are anticipated to result in changes in statistics of river flow (e.g., more extreme floods) and possibly increasing the failure probability of already aging dams. Here, we examine changes in discharge under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. In this study, we used routed daily streamflow data from ten global climate models (GCMs) in order to investigate possible climate-induced changes in streamflow in northern California. Our results show that while the average flow does not show a significant change, extreme floods are projected to increase in the future. Using the extreme value theory, we estimate changes in the return periods of 50-year and 100-year floods in the current and future climates. Finally, we use the historical and future return periods to quantify changes in failure probability of dams in a warming climate.

On a Stochastic Failure Model under Random Shocks

NASA Astrophysics Data System (ADS)

Cha, Ji Hwan

2013-02-01

In most conventional settings, the events caused by an external shock are initiated at the moments of its occurrence. In this paper, we study a new classes of shock model, where each shock from a nonhomogeneous Poisson processes can trigger a failure of a system not immediately, as in classical extreme shock models, but with delay of some random time. We derive the corresponding survival and failure rate functions. Furthermore, we study the limiting behaviour of the failure rate function where it is applicable.

Relation between lowered colloid osmotic pressure, respiratory failure, and death.

PubMed

Tonnesen, A S; Gabel, J C; McLeavey, C A

1977-01-01

Plasma colloid osmotic pressure was measured each day in 84 intensive care unit patients. Probit analysis demonstrated a direct relationship between colloid osmotic pressure (COP) and survival. The COP associated with a 50% survival rate was 15.0 torr. COP was higher in survivors than in nonsurvivors without respiratory failure and in patients who recovered from respiratory failure. We conclude that lowered COP is associated with an elevated mortality rate. However, the relationship to death is not explained by the relationship to respiratory failure.

Failure analysis and modeling of a VAXcluster system

NASA Technical Reports Server (NTRS)

Tang, Dong; Iyer, Ravishankar K.; Subramani, Sujatha S.

1990-01-01

This paper discusses the results of a measurement-based analysis of real error data collected from a DEC VAXcluster multicomputer system. In addition to evaluating basic system dependability characteristics such as error and failure distributions and hazard rates for both individual machines and for the VAXcluster, reward models were developed to analyze the impact of failures on the system as a whole. The results show that more than 46 percent of all failures were due to errors in shared resources. This is despite the fact that these errors have a recovery probability greater than 0.99. The hazard rate calculations show that not only errors, but also failures occur in bursts. Approximately 40 percent of all failures occur in bursts and involved multiple machines. This result indicates that correlated failures are significant. Analysis of rewards shows that software errors have the lowest reward (0.05 vs 0.74 for disk errors). The expected reward rate (reliability measure) of the VAXcluster drops to 0.5 in 18 hours for the 7-out-of-7 model and in 80 days for the 3-out-of-7 model.

Historic and Current Launcher Success Rates

NASA Technical Reports Server (NTRS)

Rust, Randy

2002-01-01

This presentation reviews historic and current space launcher success rates from all nations with a mature launcher industry. Data from the 1950's through present day is reviewed for possible trends such as when in the launch timeline a failure occurred, which stages had the highest failure rate, overall launcher reliability, a decade by decade look at launcher reliability, when in a launchers history did failures occur, and the reliability of United States human-rated launchers. This information is useful in determining where launcher reliability can be improved and where additional measures for crew survival (i.e., Crew Escape systems) will have the greatest emphasis

[Reduction of rehospitalisation on elderly heart failure patients: A retrospective cohort VISage network].

PubMed

Labranche, D; Mestre-Fernandes, C; Delahaye, F; Sanchez, S

2016-11-01

Heart failure was a public health problem for one million of French patients. Patients are particularly concerned in rehospitalisation for this chronic pathology. A specific healthcare network was created to take care of patients with heart failure directly at home. This healthcare network (named VISage) brings a specific and adapted monitoring in heart failure. The main of this study was to evaluate the impact of healthcare network in rehospitalisation rate for heart failure of patients. We conducted a retrospective cohort study with patients' hospital files of the CH Vienne. Patients who were included in our healthcare network (VISage) were screened. Primary endpoint was 30days, 6 months, and 1year rehospitalisation rate for heart failure before and after using healthcare network. One hundred and four patients with comorbidities were included between February 2009 and November 2015. A significant reduction of rehospitalisation rate for heart failure was observed before and after network: 0.65 (±0.52) vs. 0.17 (±0.43) 30days, 1.17 (±0.74) vs. 0.42 (±0.71) at 6 months and 1.35 (±0.95) vs. 0.47 (±0.74) at 1 year (P<0.0001). Results were significant for global rehospitalisation rate too. No significant differences were shown on hospital length of stay. Coordinated healthcare by a specific network at home for elderly is benefic for the rehospitalisation rate. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Local Failure in Resected N1 Lung Cancer: Implications for Adjuvant Therapy

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

Higgins, Kristin A., E-mail: kristin.higgins@duke.edu; Chino, Junzo P.; Berry, Mark

2012-06-01

Purpose: To evaluate actuarial rates of local failure in patients with pathologic N1 non-small-cell lung cancer and to identify clinical and pathologic factors associated with an increased risk of local failure after resection. Methods and Materials: All patients who underwent surgery for non-small-cell lung cancer with pathologically confirmed N1 disease at Duke University Medical Center from 1995-2008 were identified. Patients receiving any preoperative therapy or postoperative radiotherapy or with positive surgical margins were excluded. Local failure was defined as disease recurrence within the ipsilateral hilum, mediastinum, or bronchial stump/staple line. Actuarial rates of local failure were calculated with the Kaplan-Meiermore » method. A Cox multivariate analysis was used to identify factors independently associated with a higher risk of local recurrence. Results: Among 1,559 patients who underwent surgery during the time interval, 198 met the inclusion criteria. Of these patients, 50 (25%) received adjuvant chemotherapy. Actuarial (5-year) rates of local failure, distant failure, and overall survival were 40%, 55%, and 33%, respectively. On multivariate analysis, factors associated with an increased risk of local failure included a video-assisted thoracoscopic surgery approach (hazard ratio [HR], 2.5; p = 0.01), visceral pleural invasion (HR, 2.1; p = 0.04), and increasing number of positive N1 lymph nodes (HR, 1.3 per involved lymph node; p = 0.02). Chemotherapy was associated with a trend toward decreased risk of local failure that was not statistically significant (HR, 0.61; p = 0.2). Conclusions: Actuarial rates of local failure in pN1 disease are high. Further investigation of conformal postoperative radiotherapy may be warranted.« less

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

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

Mercer, Brian Scott

2016-05-19

In this work, molecular dynamics modeling is used to study the mechanical properties of PPTA crystallites, which are the fundamental microstructural building blocks of polymer aramid bers such as Kevlar. Particular focus is given to constant strain rate axial loading simulations of PPTA crystallites, which is motivated by the rate-dependent mechanical properties observed in some experiments with aramid bers. In order to accommodate the covalent bond rupture that occurs in loading a crystallite to failure, the reactive bond order force eld ReaxFF is employed to conduct the simulations. Two major topics are addressed: The rst is the general behavior ofmore » PPTA crystallites under strain rate loading. Constant strain rate loading simulations of crystalline PPTA reveal that the crystal failure strain increases with increasing strain rate, while the modulus is not a ected by the strain rate. Increasing temperature lowers both the modulus and the failure strain. The simulations also identify the C N bond connecting the aromatic rings as weakest primary bond along the backbone of the PPTA chain. The e ect of chain-end defects on PPTA micromechanics is explored, and it is found that the presence of a chain-end defect transfers load to the adjacent chains in the hydrogen-bonded sheet in which the defect resides, but does not in uence the behavior of any other chains in the crystal. Chain-end defects are found to lower the strength of the crystal when clustered together, inducing bond failure via stress concentrations arising from the load transfer to bonds in adjacent chains near the defect site. The second topic addressed is the nature of primary and secondary bond failure in crystalline PPTA. Failure of both types of bonds is found to be stochastic in nature and driven by thermal uctuations of the bonds within the crystal. A model is proposed which uses reliability theory to model bonds under constant strain rate loading as components with time-dependent failure rate functions. The model is shown to work well for predicting the onset of primary backbone bond failure, as well as the onset of secondary bond failure via chain slippage for the case of isolated non-interacting chain-end defects.« less

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

Barbee, D; McCarthy, A; Galavis, P

Purpose: Errors found during initial physics plan checks frequently require replanning and reprinting, resulting decreased departmental efficiency. Additionally, errors may be missed during physics checks, resulting in potential treatment errors or interruption. This work presents a process control created using the Eclipse Scripting API (ESAPI) enabling dosimetrists and physicists to detect potential errors in the Eclipse treatment planning system prior to performing any plan approvals or printing. Methods: Potential failure modes for five categories were generated based on available ESAPI (v11) patient object properties: Images, Contours, Plans, Beams, and Dose. An Eclipse script plugin (PlanCheck) was written in C# tomore » check errors most frequently observed clinically in each of the categories. The PlanCheck algorithms were devised to check technical aspects of plans, such as deliverability (e.g. minimum EDW MUs), in addition to ensuring that policy and procedures relating to planning were being followed. The effect on clinical workflow efficiency was measured by tracking the plan document error rate and plan revision/retirement rates in the Aria database over monthly intervals. Results: The number of potential failure modes the PlanCheck script is currently capable of checking for in the following categories: Images (6), Contours (7), Plans (8), Beams (17), and Dose (4). Prior to implementation of the PlanCheck plugin, the observed error rates in errored plan documents and revised/retired plans in the Aria database was 20% and 22%, respectively. Error rates were seen to decrease gradually over time as adoption of the script improved. Conclusion: A process control created using the Eclipse scripting API enabled plan checks to occur within the planning system, resulting in reduction in error rates and improved efficiency. Future work includes: initiating full FMEA for planning workflow, extending categories to include additional checks outside of ESAPI via Aria database queries, and eventual automated plan checks.« less

Perceived success/failure and attributions associated with self-regulatory efficacy to meet physical activity recommendations for women with arthritis.

PubMed

Spink, Kevin S; Brawley, Lawrence R; Gyurcsik, Nancy C

2016-10-01

The relationship between attributional dimensions women assign to the cause of their perceived success or failure at meeting the recommended physical activity dose and self-regulatory efficacy for future physical activity was examined among women with arthritis. Women (N = 117) aged 18-84 years, with self-reported medically-diagnosed arthritis, completed on-line questions in the fall of 2013 assessing endurance physical activity, perceived outcome for meeting the recommended levels of endurance activity, attributions for one's success or failure in meeting the recommendations, and self-regulatory efficacy to schedule/plan endurance activity over the next month. The main theoretically-driven finding revealed that the interaction of the stability dimension with perceived success/failure was significantly related to self-regulatory efficacy for scheduling and planning future physical activity (β = 0.35, p = .002). Outcomes attributed to more versus less stable factors accentuated differences in self-regulatory efficacy beliefs following perceived success and failure at being active. It appears that attributional dimensions were associated with self-regulatory efficacy in women with arthritis. This suggests that rather than objectively observed past mastery experience, women's subjective perceptions and explanations of their past experiences were related to efficacy beliefs, especially following a failure experience.

Assessment of the Accuracy and Cut-Failure Rates of Eye Bank-Cut Corneas for Use in Endothelial Keratoplasty: A Comparison of Outcomes Between 2010 and 2013.

PubMed

Katzman, Lee R; Hoover, Caroline K; Khalifa, Yousuf M; Jeng, Bennie H

2015-11-01

To evaluate the accuracy of eye bank-prepared precut donor corneas over time by comparing cut-failure rates and corneal thickness measurements in 2010 and 2013. A total of 2511 human corneas cut by a technician-operated mechanical microkeratome intended for endothelial keratoplasty were evaluated prospectively at one large eye bank facility in 2010 and in 2013. The endothelium was evaluated by slit lamp, and specular microscopy both before and after cutting was performed. Graft thickness as measured by pachymetry and/or optical coherence tomography was collected to assess the accuracy of the cut tissue. Cut-failure rates were compared between normal donor tissue and tissue with significant preexisting scarring. The combined cut-failure rate in 2010 and 2013 was 2.3% (23/1000) and 1.6% (24/1511), respectively (P = 0.23). The cut-failure rate among normal tissue in 2010 and 2013 was 2.0% (19/927) and 1.4% (19/1400), respectively (P = 0.24). The cut-failure rate among previously scarred tissue in 2010 and 2013 was 5.5% (4/73) and 4.5% (5/111), respectively (P = 0.74). The mean surgeon-requested graft thickness was 144.7 μm (range 100-150, SD 13.6) and 127.2 μm (range 75-150, SD 25.2) in 2010 and 2013, respectively (P < 0.0001). The mean deviation from target graft thickness was 21.3 μm (SD 16.3) and 13.6 μm (SD 12.5) in 2010 and 2013, respectively (P < 0.0001). From 2010 to 2013, the combined cut-failure rates trended toward improvement, while the accuracy of graft thickness improved. This study suggests that the accuracy and success rates of tissue preparation for endothelial keratoplasty improve with experience and volume.

A large silent earthquake and the future rupture of the Guerrero seismic

NASA Astrophysics Data System (ADS)

Kostoglodov, V.; Lowry, A.; Singh, S.; Larson, K.; Santiago, J.; Franco, S.; Bilham, R.

2003-04-01

The largest global earthquakes typically occur at subduction zones, at the seismogenic boundary between two colliding tectonic plates. These earthquakes release elastic strains accumulated over many decades of plate motion. Forecasts of these events have large errors resulting from poor knowledge of the seismic cycle. The discovery of slow slip events or "silent earthquakes" in Japan, Alaska, Cascadia and Mexico provides a new glimmer of hope. In these subduction zones, the seismogenic part of the plate interface is loading not steadily as hitherto believed, but incrementally, partitioning the stress buildup with the slow slip events. If slow aseismic slip is limited to the region downdip of the future rupture zone, slip events may increase the stress at the base of the seismogenic region, incrementing it closer to failure. However if some aseismic slip occurs on the future rupture zone, the partitioning may significantly reduce the stress buildup rate (SBR) and delay a future large earthquake. Here we report characteristics of the largest slow earthquake observed to date (Mw 7.5), and its implications for future failure of the Guerrero seismic gap, Mexico. The silent earthquake began in October 2001 and lasted for 6-7 months. Slow slip produced measurable displacements over an area of 550x250 km2. Average slip on the interface was about 10 cm and the equivalent magnitude, Mw, was 7.5. A shallow subhorizontal configuration of the plate interface in Guererro is a controlling factor for the physical conditions favorable for such extensive slow slip. The total coupled zone in Guerrero is 120-170 km wide while the seismogenic, shallowest portion is only 50 km. This future rupture zone may slip contemporaneously with the deeper aseismic sleep, thereby reducing SBR. The slip partitioning between seismogenic and transition coupled zones may diminish SBR up to 50%. These two factors are probably responsible for a long (at least since 1911) quiet on the Guerrero seismic gap in Mexico. The discovery of silent earthquakes in Guerrero in 1972, 1979, 1998, and 2001-2002 calls for a reassessment of the seismic potential and careful seismotectonic monitoring of the seismic gaps in Mexico.

Systematic studies of modified vocalization: the effect of speech rate on speech production measures during metronome-paced speech in persons who stutter.

PubMed

Davidow, Jason H

2014-01-01

Metronome-paced speech results in the elimination, or substantial reduction, of stuttering moments. The cause of fluency during this fluency-inducing condition is unknown. Several investigations have reported changes in speech pattern characteristics from a control condition to a metronome-paced speech condition, but failure to control speech rate between conditions limits our ability to determine if the changes were necessary for fluency. This study examined the effect of speech rate on several speech production variables during one-syllable-per-beat metronomic speech in order to determine changes that may be important for fluency during this fluency-inducing condition. Thirteen persons who stutter (PWS), aged 18-62 years, completed a series of speaking tasks. Several speech production variables were compared between conditions produced at different metronome beat rates, and between a control condition and a metronome-paced speech condition produced at a rate equal to the control condition. Vowel duration, voice onset time, pressure rise time and phonated intervals were significantly impacted by metronome beat rate. Voice onset time and the percentage of short (30-100 ms) phonated intervals significantly decreased from the control condition to the equivalent rate metronome-paced speech condition. A reduction in the percentage of short phonated intervals may be important for fluency during syllable-based metronome-paced speech for PWS. Future studies should continue examining the necessity of this reduction. In addition, speech rate must be controlled in future fluency-inducing condition studies, including neuroimaging investigations, in order for this research to make a substantial contribution to finding the fluency-inducing mechanism of fluency-inducing conditions. © 2013 Royal College of Speech and Language Therapists.

Systematic Studies of Modified Vocalization: The Effect of Speech Rate on Speech Production Measures During Metronome-Paced Speech in Persons who Stutter

PubMed Central

Davidow, Jason H.

2013-01-01

Background Metronome-paced speech results in the elimination, or substantial reduction, of stuttering moments. The cause of fluency during this fluency-inducing condition is unknown. Several investigations have reported changes in speech pattern characteristics from a control condition to a metronome-paced speech condition, but failure to control speech rate between conditions limits our ability to determine if the changes were necessary for fluency. Aims This study examined the effect of speech rate on several speech production variables during one-syllable-per-beat metronomic speech, in order to determine changes that may be important for fluency during this fluency-inducing condition. Methods and Procedures Thirteen persons who stutter (PWS), aged 18–62 years, completed a series of speaking tasks. Several speech production variables were compared between conditions produced at different metronome beat rates, and between a control condition and a metronome-paced speech condition produced at a rate equal to the control condition. Outcomes & Results Vowel duration, voice onset time, pressure rise time, and phonated intervals were significantly impacted by metronome beat rate. Voice onset time and the percentage of short (30–100 ms) phonated intervals significantly decreased from the control condition to the equivalent rate metronome-paced speech condition. Conclusions & Implications A reduction in the percentage of short phonated intervals may be important for fluency during syllable-based metronome-paced speech for PWS. Future studies should continue examining the necessity of this reduction. In addition, speech rate must be controlled in future fluency-inducing condition studies, including neuroimaging investigations, in order for this research to make a substantial contribution to finding the fluency-inducing mechanism of fluency-inducing conditions. PMID:24372888

77 FR 54864 - Federal Acquisition Regulation; Documenting Contractor Performance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-06

....g., late or nonpayment to subcontractors, trafficking violations, tax delinquency, failure to report... applicable) (e.g.; late or nonpayment to subcontractors, trafficking violations, tax delinquency, failure to... that allowing contractors to ``report to the CPARS system'' would have a negative impact on future...

Nutritional Interventions in Heart Failure: A Systematic Review of the Literature.

PubMed

Abshire, Martha; Xu, Jiayun; Baptiste, Diana; Almansa, Johana R; Xu, Jingzhi; Cummings, Abby; Andrews, Martha J; Dennison Himmelfarb, Cheryl

2015-12-01

Heart failure (HF) is a major health care burden and there is a growing need to develop strategies to maintain health and sustain quality of life in persons with HF. The purpose of this review is to critically appraise the components of nutrition interventions and to establish an evidence base for future advances in HF nutrition research and practice. Cinahl, Pubmed, and Embase were searched to identify articles published from 2005 to 2015. A total of 17 randomized controlled trials were included in this review. Results were divided into 2 categories of nutrition-related interventions: (1) educational and (2) prescriptive. Educational interventions improved patient outcomes such as adherence to dietary restriction in urine sodium levels and self-reported diet recall. Educational and prescriptive interventions resulted in decreased readmission rates and patient deterioration. Adherence measurement was subjective in many studies. Evidence showed that a normal-sodium diet and 1-liter fluid restriction along with high diuretic dosing enhanced B-type natriuretic peptide, aldosterone, tumor necrosis factor α, and interleukin-6 markers. Educational nutrition interventions positively affect patient clinical outcomes. Although clinical practice guidelines support a low-sodium diet and fluid restriction, research findings have revealed that a low-sodium diet may be harmful. Future research should examine the role of macronutrients, food quality, and energy balance in HF nutrition. Copyright © 2015 Elsevier Inc. All rights reserved.

Nursing research in heart failure care: a position statement of the american association of heart failure nurses (AAHFN).

PubMed

Stamp, Kelly D; Prasun, Marilyn; Lee, Christopher S; Jaarsma, Tiny; Piano, Mariann R; Albert, Nancy M

Heart Failure (HF) is a public health problem globally affecting approximately 6 million in the United States. A tailored position statement was developed by the American Association of Heart Failure Nurses (AAHFN) and their Research Consortium to assist researchers, funding institutions and policymakers with improving HF clinical advancements and outcomes. A comprehensive review was conducted using multiple search terms in various combinations to describe gaps in HF nursing science. Based on gaps described in the literature, the AAHFN made recommendations for future areas of research in HF. Nursing has made positive contributions through disease management interventions, however, quality, rigorous research is needed to improve the lives of patients and families while advancing nursing science. Advancing HF science is critical to managing and improving patient outcomes while promoting the nursing profession. Based on this review, the AAHFN is putting forth a call to action for research designs that promote validity, sustainability, and funding of future nursing research. Copyright © 2018 Elsevier Inc. All rights reserved.

KAMEDO report No. 93-the power failure at Karolinska University Hospital, Huddinge, 07 April 2007.

PubMed

Angantyr, Lars-Göran; Häggström, Eskil; Kulling, Per

2009-01-01

A sudden and extensive power failure occurred at Karolinska University Hospital in Huddinge on Easter Saturday, 07 April 2007. The power failure lasted one hour and 22 minutes, but it took a longer time for activities to return to normal. It put many patients at great risk, particularly in the intensive care unit and other departments with critically ill patients. This report details the conditions and response at Karolinska University Hospital during the power failure and provides lessons learned for future events.

Urine neutrophil gelatinase-associated lipocalin and risk of cardiovascular disease and death in CKD: results from the Chronic Renal Insufficiency Cohort (CRIC) Study.

PubMed

Liu, Kathleen D; Yang, Wei; Go, Alan S; Anderson, Amanda H; Feldman, Harold I; Fischer, Michael J; He, Jiang; Kallem, Radhakrishna R; Kusek, John W; Master, Stephen R; Miller, Edgar R; Rosas, Sylvia E; Steigerwalt, Susan; Tao, Kaixiang; Weir, Matthew R; Hsu, Chi-Yuan

2015-02-01

Chronic kidney disease is common and is associated with increased cardiovascular disease risk. Currently, markers of renal tubular injury are not used routinely to describe kidney health and little is known about the risk of cardiovascular events and death associated with these biomarkers independent of glomerular filtration-based markers (such as serum creatinine or albuminuria). Cohort study, CRIC (Chronic Renal Insufficiency Cohort) Study. 3,386 participants with estimated glomerular filtration rate of 20 to 70mL/min/1.73m(2) enrolled from June 2003 through August 2008. Urine neutrophil gelatinase-associated lipocalin (NGAL) concentration. Adjudicated heart failure event, ischemic atherosclerotic event (myocardial infarction, ischemic stroke, or peripheral artery disease), and death through March 2011. Urine NGAL measured at baseline with a 2-step assay using chemiluminescent microparticle immunoassay technology on an ARCHITECT i2000SR (Abbott Laboratories). There were 428 heart failure events (during 16,383 person-years of follow-up), 361 ischemic atherosclerotic events (during 16,584 person-years of follow-up), and 522 deaths (during 18,214 person-years of follow-up). In Cox regression models adjusted for estimated glomerular filtration rate, albuminuria, demographics, traditional cardiovascular disease risk factors, and cardiac medications, higher urine NGAL levels remained associated independently with ischemic atherosclerotic events (adjusted HR for the highest [>49.5ng/mL] vs lowest [≤6.9ng/mL] quintile, 1.83 [95% CI, 1.20-2.81]; HR per 0.1-unit increase in log urine NGAL, 1.012 [95% CI, 1.001-1.023]), but not heart failure events or deaths. Urine NGAL was measured only once. Among patients with chronic kidney disease, urine levels of NGAL, a marker of renal tubular injury, were associated independently with future ischemic atherosclerotic events, but not with heart failure events or deaths. Copyright © 2015 National Kidney Foundation, Inc. All rights reserved.

Mechanisms, predictors, and trends of electrical failure of Riata leads.

PubMed

Cheung, Jim W; Al-Kazaz, Mohamed; Thomas, George; Liu, Christopher F; Ip, James E; Bender, Seth R; Siddiqi, Faisal K; Markowitz, Steven M; Lerman, Bruce B

2013-10-01

Riata and Riata ST implantable cardioverter-defibrillator leads have been shown to be prone to structural and electrical failure. To determine predictors, mechanisms, and temporal patterns of Riata/ST lead electrical failure. All 314 patients who underwent Riata/ST lead implantation at our institution with greater than or equal to 90 days of follow-up were studied. The Kaplan-Meier analysis of lead survival was performed. Results from the returned product analysis of explanted leads with electrical lead failure were recorded. During a median follow-up of 4.1 years, the Riata lead electrical failure rate was 6.6%. The rate of externalized conductors among failed leads was 57%. The engineering analysis of 10 explanted leads revealed 5 (50%) leads with electrical failure owing to breach of ethylene tetrafluoroethylene conductor coating. Female gender (hazard ratio 2.7; 95% confidence interval 1.1-6.7; P = .04) and age (hazard ratio 0.95; 95% confidence interval 0.92-0.97; P < .001) were multivariate predictors of lead failure. By using log-log analysis, we noted that the rate of Riata lead failure initially increased exponentially with a power of 2.1 but leads surviving past 4 years had a linear pattern of lead failure with a power of 1.0. Younger age and female gender are independent predictors of Riata lead failure. Loss of integrity of conductor cables with ethylene tetrafluoroethylene coating is an important mode of electrical failure of the Riata lead. Further study of Riata lead failure trends is warranted to guide lead management. © 2013 Heart Rhythm Society. All rights reserved.

Percutaneous radiofrequency ablation of hepatic tumours: factors affecting technical failure of artificial ascites formation using an angiosheath.

PubMed

Kang, T W; Lee, M W; Hye, M J; Song, K D; Lim, S; Rhim, H; Lim, H K; Cha, D I

2014-12-01

To evaluate the technical feasibility of artificial ascites formation using an angiosheath before percutaneous radiofrequency ablation (RFA) for hepatic tumours and to determine predictive factors affecting the technical failure of artificial ascites formation. This retrospective study was approved by the institutional review board. One hundred and thirteen patients underwent percutaneous RFA of hepatic tumours after trying to make artificial ascites using an angiosheath to avoid collateral thermal damage. The technical success rate of making artificial ascites using an angiosheath and conversion rate to other techniques after initial failure of making artificial ascites were evaluated. The technical success rate for RFA was assessed. In addition, potential factors associated with technical failure including previous history of transcatheter arterial chemoembolization (TACE) or RFA, type of abdominal surgery, and adjacent perihepatic structures were reviewed. Predictive factors for the technical failure of artificial ascites formation were analysed using multivariate analysis. The technical success rates of artificial ascites formation by angiosheath and that of RFA were 84.1% (95/113) and 97.3% (110/113), respectively. The conversion rate to other techniques after the failure of artificial ascites formation using an angiosheath was 15.9% (18/113). Previous hepatic resection was the sole independent predictive factor affecting the technical failure of artificial ascites formation (p<0.001, odds ratio = 29.03, 95% confidence interval: 4.56-184.69). Making artificial ascites for RFA of hepatic tumours using an angiosheath was technically feasible in most cases. However, history of hepatic resection was a significant predictive factor affecting the technical failure of artificial ascites formation. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

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

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

PubMed

AlHindi, Maryam; Rashed, Bayan; AlOtaibi, Noura

2016-01-01

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.   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.   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%).  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.

Anti-arrhythmic strategies for atrial fibrillation

PubMed Central

Grandi, Eleonora; Maleckar, Mary M.

2016-01-01

Atrial fibrillation (AF), the most common cardiac arrhythmia, is associated with increased risk of cerebrovascular stroke, and with several other pathologies, including heart failure. Current therapies for AF are targeted at reducing risk of stroke (anticoagulation) and tachycardia-induced cardiomyopathy (rate or rhythm control). Rate control, typically achieved by atrioventricular nodal blocking drugs, is often insufficient to alleviate symptoms. Rhythm control approaches include antiarrhythmic drugs, electrical cardioversion, and ablation strategies. Here, we offer several examples of how computational modeling can provide a quantitative framework for integrating multi scale data to: (a) gain insight into multi-scale mechanisms of AF; (b) identify and test pharmacological and electrical therapy and interventions; and (c) support clinical decisions. We review how modeling approaches have evolved and contributed to the research pipeline and preclinical development and discuss future directions and challenges in the field. PMID:27612549

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.

Scaling of coupled dilatancy-diffusion processes in space and time

NASA Astrophysics Data System (ADS)

Main, I. G.; Bell, A. F.; Meredith, P. G.; Brantut, N.; Heap, M.

2012-04-01

Coupled dilatancy-diffusion processes resulting from microscopically brittle damage due to precursory cracking have been observed in the laboratory and suggested as a mechanism for earthquake precursors. One reason precursors have proven elusive may be the scaling in space: recent geodetic and seismic data placing strong limits on the spatial extent of the nucleation zone for recent earthquakes. Another may be the scaling in time: recent laboratory results on axi-symmetric samples show both a systematic decrease in circumferential extensional strain at failure and a delayed and a sharper acceleration of acoustic emission event rate as strain rate is decreased. Here we examine the scaling of such processes in time from laboratory to field conditions using brittle creep (constant stress loading) to failure tests, in an attempt to bridge part of the strain rate gap to natural conditions, and discuss the implications for forecasting the failure time. Dilatancy rate is strongly correlated to strain rate, and decreases to zero in the steady-rate creep phase at strain rates around 10-9 s-1 for a basalt from Mount Etna. The data are well described by a creep model based on the linear superposition of transient (decelerating) and accelerating micro-crack growth due to stress corrosion. The model produces good fits to the failure time in retrospect using the accelerating acoustic emission event rate, but in prospective tests on synthetic data with the same properties we find failure-time forecasting is subject to systematic epistemic and aleatory uncertainties that degrade predictability. The next stage is to use the technology developed to attempt failure forecasting in real time, using live streamed data and a public web-based portal to quantify the prospective forecast quality under such controlled laboratory conditions.

Syndromic surveillance for health information system failures: a feasibility study.

PubMed

Ong, Mei-Sing; Magrabi, Farah; Coiera, Enrico

2013-05-01

To explore the applicability of a syndromic surveillance method to the early detection of health information technology (HIT) system failures. A syndromic surveillance system was developed to monitor a laboratory information system at a tertiary hospital. Four indices were monitored: (1) total laboratory records being created; (2) total records with missing results; (3) average serum potassium results; and (4) total duplicated tests on a patient. The goal was to detect HIT system failures causing: data loss at the record level; data loss at the field level; erroneous data; and unintended duplication of data. Time-series models of the indices were constructed, and statistical process control charts were used to detect unexpected behaviors. The ability of the models to detect HIT system failures was evaluated using simulated failures, each lasting for 24 h, with error rates ranging from 1% to 35%. In detecting data loss at the record level, the model achieved a sensitivity of 0.26 when the simulated error rate was 1%, while maintaining a specificity of 0.98. Detection performance improved with increasing error rates, achieving a perfect sensitivity when the error rate was 35%. In the detection of missing results, erroneous serum potassium results and unintended repetition of tests, perfect sensitivity was attained when the error rate was as small as 5%. Decreasing the error rate to 1% resulted in a drop in sensitivity to 0.65-0.85. Syndromic surveillance methods can potentially be applied to monitor HIT systems, to facilitate the early detection of failures.

Age and admission times as predictive factors for failure of admissions to discharge-stream short-stay units.

PubMed

Shetty, Amith L; Shankar Raju, Savitha Banagar; Hermiz, Arsalan; Vaghasiya, Milan; Vukasovic, Matthew

2015-02-01

Discharge-stream emergency short-stay units (ESSU) improve ED and hospital efficiency. Age of patients and time of hospital presentations have been shown to correlate with increasing complexity of care. We aim to determine whether an age and time cut-off could be derived to subsequently improve short-stay unit success rates. We conducted a retrospective audit on 6703 (5522 inclusions) patients admitted to our discharge-stream short-stay unit. Patients were classified as appropriate or inappropriate admissions, and deemed successful if discharged out of the unit within 24 h; and failures if they needed inpatient admission into the hospital. We calculated short-stay unit length of stay for patients in each of these groups. A 15% failure rate was deemed as acceptable key performance indicator (KPI) for our unit. There were 197 out of 4621 (4.3%, 95% CI 3.7-4.9%) patients up to the age of 70 who failed admission to ESSU compared with 67 out of 901 (7.4%, 95% CI 5.9-9.3%, P < 0.01) of patients over the age of 70, reflecting an increased failure rate in geriatric population. When grouped according to times of admission to the ESSU (in-office 06.00-22.00 hours vs out-of-office 22.00-06.00 hours) no significant difference rates in discharge failure (4.7% vs 5.2%, P = 0.46) were noted. Patients >70 years of age have higher rates of failure after admission to discharge-stream ESSU. Although in appropriately selected discharge-stream patients, no age group or time-band of presentation was associated with increased failure rate beyond the stipulated KPI. © 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

"Future Proofing" Faculty: The Struggle To Create Technical Lifelong Learners.

ERIC Educational Resources Information Center

Nay, Fred W.; Malm, Loren D.; Malone, Bobby G.; Oliver, Brad E.; Saunders, Nancy G.; Thompson, Jay C., Jr.

College faculty can avoid investing valuable time and resources in inappropriate technologies by staying in step with technological progress. A "future proof" approach to technology recognizes and welcomes small failures, considering them part of the ongoing process of absorbing technology into the learning process. Future proofing attempts to…

Reducing the Risk of Human Space Missions with INTEGRITY

NASA Technical Reports Server (NTRS)

Jones, Harry W.; Dillon-Merill, Robin L.; Tri, Terry O.; Henninger, Donald L.

2003-01-01

The INTEGRITY Program will design and operate a test bed facility to help prepare for future beyond-LEO missions. The purpose of INTEGRITY is to enable future missions by developing, testing, and demonstrating advanced human space systems. INTEGRITY will also implement and validate advanced management techniques including risk analysis and mitigation. One important way INTEGRITY will help enable future missions is by reducing their risk. A risk analysis of human space missions is important in defining the steps that INTEGRITY should take to mitigate risk. This paper describes how a Probabilistic Risk Assessment (PRA) of human space missions will help support the planning and development of INTEGRITY to maximize its benefits to future missions. PRA is a systematic methodology to decompose the system into subsystems and components, to quantify the failure risk as a function of the design elements and their corresponding probability of failure. PRA provides a quantitative estimate of the probability of failure of the system, including an assessment and display of the degree of uncertainty surrounding the probability. PRA provides a basis for understanding the impacts of decisions that affect safety, reliability, performance, and cost. Risks with both high probability and high impact are identified as top priority. The PRA of human missions beyond Earth orbit will help indicate how the risk of future human space missions can be reduced by integrating and testing systems in INTEGRITY.

Symptoms and fear in heart failure patients approaching end of life: a mixed methods study.

PubMed

Abshire, Martha; Xu, Jiayun; Dennison Himmelfarb, Cheryl; Davidson, Patricia; Sulmasy, Daniel; Kub, Joan; Hughes, Mark; Nolan, Marie

2015-11-01

The purpose of this study was to consider how fear and symptom experience are perceived in patients with heart failure at the end of life. Heart failure is a burdensome condition and mortality rates are high globally. There is substantive literature describing suffering and unmet needs but description of the experience of fear and the relationship with symptom burden is limited. A convergent mixed methods design was used. Data from the McGill Quality of Life Questionnaire (n = 55) were compared to data from in-depth interviews (n = 5). Patients denied fear when asked directly, but frequently referred to moments of being afraid when they were experiencing symptoms. In addition, patients reported few troublesome symptoms on the survey, but mentioned many more symptoms during interviews. These data not only identify the relationship between psychological issues and symptom experience but also elucidate the benefit of a mixed method approach in describing such experiences from the perspective of the patient. Future research should examine relationships between and among symptom experience, fear and other psychological constructs across the illness trajectory. Conversations about the interaction of symptom burden and fear can lead to both a more robust assessment of symptoms and lead to patient centred interventions. © 2015 John Wiley & Sons Ltd.

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.

A review of economic evaluation models for cardiac resynchronization therapy with implantable cardioverter defibrillators in patients with heart failure.

PubMed

Tomini, F; Prinzen, F; van Asselt, A D I

2016-12-01

Cardiac resynchronization therapy with a biventricular pacemaker (CRT-P) is an effective treatment for dyssynchronous heart failure (DHF). Adding an implantable cardioverter defibrillator (CRT-D) may further reduce the risk of sudden cardiac death (SCD). However, if the majority of patients do not require shock therapy, the cost-effectiveness ratio of CRT-D compared to CRT-P may be high. The objective of this study was to systematically review decision models evaluating the cost-effectiveness of CRT-D for patients with DHF, compare the structure and inputs of these models and identify the main factors influencing the ICERs for CRT-D. A comprehensive search strategy of Medline (Ovid), Embase (Ovid) and EconLit identified eight cost-effectiveness models evaluating CRT-D against optimal pharmacological therapy (OPT) and/or CRT-P. The selected economic studies differed in terms of model structure, treatment path, time horizons, and sources of efficacy data. CRT-D was found cost-effective when compared to OPT but its cost-effectiveness became questionable when compared to CRT-P. Cost-effectiveness of CRT-D may increase depending on improvement of all-cause mortality rates and HF mortality rates in patients who receive CRT-D, costs of the device, and battery life. In particular, future studies need to investigate longer-term mortality rates and identify CRT-P patients that will gain the most, in terms of life expectancy, from being treated with a CRT-D.

Autotransplantation of teeth in humans: a systematic review and meta-analysis.

PubMed

Almpani, Konstantinia; Papageorgiou, Spyridon N; Papadopoulos, Moschos A

2015-07-01

The aim of this investigation was to assess the currently available evidence concerning the complications and risk factors influencing the outcome of autotransplantation of teeth in humans. Electronic searches were conducted to identify randomized controlled and prospective clinical trials. Risk of bias within studies was assessed with the Downs and Black tool. Random-effects meta-analyses were conducted to pool the adverse event rates and relative risks with their 95% confidence intervals. Risk of bias across studies was assessed with the GRADE framework followed by sensitivity analyses. Thirty-eight studies were included in the analysis. Reported complications included the need for extraction, failure, hypermobility, pulp necrosis, pulp obliteration, and root resorption. Pooled complication event rates varied considerably, with small studies (<100 teeth) reporting greater complication rates. The analysis of risk factors was associated with both the primary outcome (extraction need) and secondary outcomes (failure, hypermobility, pulp necrosis, pulp obliteration, root resorption). The stage of root development seems to influence both the future survival, as well as the success of the transplanted teeth. Teeth with open apex were less likely to be extracted in comparison to teeth with closed apex (3 studies; 413 teeth; relative risk 0.3; 95% confidence interval 0.2-0.6). Due to the small number of the contributing studies, their methodological limitations, and the heterogeneous results reported, no firm conclusions can be drawn. Root development of the donor teeth has been established as one the most important factor related to the success of tooth autotransplantation.

A new kid on the block: The Memory Validity Profile (MVP) in children with neurological conditions.

PubMed

Brooks, Brian L; Fay-McClymont, Taryn B; MacAllister, William S; Vasserman, Marsha; Sherman, Elisabeth M S

2018-06-06

Determining the validity of obtained data is an inherent part of a neuropsychological assessment. The purpose of this study was investigate the failure rate of the Memory Validity Profile (MVP) in a large clinical sample of children and adolescents with neurological diagnoses. Data were obtained from 261 consecutive patients (mean age = 12.0, SD = 3.9, range = 5-19) who were referred for a neuropsychological assessment in a tertiary care pediatric hospital and were administered the MVP. In this sample, 4.6% of youth failed the MVP. Mean administration time for the MVP was 7.4 min, although time to complete was not associated with failure rates. Failure rates were held relatively consistent at approximately 5% across age ranges, diagnoses, and psychomotor processing speed abilities. Having very low, below normal, or above normal intellectual abilities did not alter failure rate on the MVP. However, those with intellectual disability (i.e., IQ<70) had a higher fail rate at 12% on MVP Total Score, but only 6% on the MVP Visual portion. Failure rates on the MVP were associated with lower scores on memory tests. This study provides support for using the MVP in children as young as 5 years with neurological diagnoses.

Effect of Strain Rate on Joint Strength and Failure Mode of Lead-Free Solder Joints

NASA Astrophysics Data System (ADS)

Lin, Jian; Lei, Yongping; Fu, Hanguang; Guo, Fu

2018-03-01

In surface mount technology, the Sn-3.0Ag-0.5Cu solder joint has a shorter impact lifetime than a traditional lead-tin solder joint. In order to improve the impact property of SnAgCu lead-free solder joints and identify the effect of silver content on tensile strength and impact property, impact experiments were conducted at various strain rates on three selected SnAgCu based solder joints. It was found that joint failure mainly occurred in the solder material with large plastic deformation under low strain rate, while joint failure occurred at the brittle intermetallic compound layer without any plastic deformation at a high strain rate. Joint strength increased with the silver content in SnAgCu alloys in static tensile tests, while the impact property of the solder joint decreased with increasing silver content. When the strain rate was low, plastic deformation occurred with failure and the tensile strength of the Sn-3.0Ag-0.5Cu solder joint was higher than that of Sn-0.3Ag-0.7Cu; when the strain rate was high, joint failure mainly occurred at the brittle interface layer and the Sn-0.3Ag-0.7Cu solder joint had a better impact resistance with a thinner intermetallic compound layer.

Cloudy outlook. Supercommittee failure leaves healthcare providers questioning future cuts, impact on hospitals.

PubMed

Zigmond, Jessica

2011-11-28

President Barack Obama responded to the failure of the so-called supercommittee with a message that he won't allow Congress to water down the automatic cuts triggered under the August deficit law, which would include a 2% reduction in Medicare payments.

STS-3 main parachute failure

NASA Technical Reports Server (NTRS)

Runkle, R.; Henson, K.

1982-01-01

A failure analysis of the parachute on the Space Transportation System 3 flight's solid rocket booster's is presented. During the reentry phase of the two Solid Rocket Boosters (SRBs), one 115 ft diameter main parachute failed on the right hand SRB (A12). This parachute failure caused the SRB to impact the Ocean at 110 ft/sec in lieu of the expected 3 parachute impact velocity of 88 ft/sec. This higher impact velocity relates directly to more SRB aft skirt and more motor case damage. The cause of the parachute failure, the potential risks of losing an SRB as a result of this failure, and recommendations to ensure that the probability of chute failures of this type in the future will be low are discussed.

Mechanistic analysis of time-dependent failure of oxynitride glass-joined silicon nitride below 1000 degree C

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

O'Brien, M.H.; Coon, D.M.

Time-dependent failure at elevated temperatures currently governs the service life of oxynitride glass-joined silicon nitride. Creep, devitrification, stress- aided oxidation-controlled slow crack growth, and viscous cabitation-controlled failure are examined as possible controlling mechanisms. Creep deformation failure is observed above 1000{degrees}C. Fractographic evidence indicates cavity formation and growth below 1000{degrees}C. Auger electron spectroscopy verified that the oxidation rate of the joining glass is governed by the oxygen supply rate. Time-to-failure data and those predicted using the Tsai and Raj, and Raj and Dang viscous cavitation models. It is concluded that viscous relaxation and isolated cavity growth control the rate of failuremore » in oxynitride glass-filled silicon nitride joints below 1000{degrees}C. Several possible methods are also proposed for increasing the service lives of these joints.« less

Externalized conductors and insulation failure in Biotronik defibrillator leads: History repeating or a false alarm?

PubMed

De Maria, Elia; Borghi, Ambra; Bonetti, Lorenzo; Fontana, Pier Luigi; Cappelli, Stefano

2017-02-16

Conductor externalization and insulation failure are frequent complications with the recalled St. Jude Medical Riata implantable cardioverter-defibrillator (ICD) leads. Conductor externalization is a "unique" failure mechanism: Cables externalize through the insulation ("inside-out" abrasion) and appear outside the lead body. Recently, single reports described a similar failure also for Biotronik leads. Moreover, some studies reported a high rate of electrical dysfunction (not only insulation failure) with Biotronik Linox leads and a reduced survival rate in comparison with the competitors. In this paper we describe the case of a patient with a Biotronik Kentrox ICD lead presenting with signs of insulation failure and conductor externalization at fluoroscopy. Due to the high risk of extraction we decided to implant a new lead, abandoning the damaged one; lead reimplant was uneventful. Subsequently, we review currently available literature about Biotronik Kentrox and Linox ICD lead failure and in particular externalized conductors. Some single-center studies and a non-prospective registry reported a survival rate between 88% and 91% at 5 years for Linox leads, significantly worse than that of other manufacturers. However, the preliminary results of two ongoing multicenter, prospective registries (GALAXY and CELESTIAL) showed 96% survival rate at 5 years after implant, well within industry standards. Ongoing data collection is needed to confirm longer-term performance of this family of ICD leads.

Externalized conductors and insulation failure in Biotronik defibrillator leads: History repeating or a false alarm?

PubMed Central

De Maria, Elia; Borghi, Ambra; Bonetti, Lorenzo; Fontana, Pier Luigi; Cappelli, Stefano

2017-01-01

Conductor externalization and insulation failure are frequent complications with the recalled St. Jude Medical Riata implantable cardioverter-defibrillator (ICD) leads. Conductor externalization is a “unique” failure mechanism: Cables externalize through the insulation (“inside-out” abrasion) and appear outside the lead body. Recently, single reports described a similar failure also for Biotronik leads. Moreover, some studies reported a high rate of electrical dysfunction (not only insulation failure) with Biotronik Linox leads and a reduced survival rate in comparison with the competitors. In this paper we describe the case of a patient with a Biotronik Kentrox ICD lead presenting with signs of insulation failure and conductor externalization at fluoroscopy. Due to the high risk of extraction we decided to implant a new lead, abandoning the damaged one; lead reimplant was uneventful. Subsequently, we review currently available literature about Biotronik Kentrox and Linox ICD lead failure and in particular externalized conductors. Some single-center studies and a non-prospective registry reported a survival rate between 88% and 91% at 5 years for Linox leads, significantly worse than that of other manufacturers. However, the preliminary results of two ongoing multicenter, prospective registries (GALAXY and CELESTIAL) showed 96% survival rate at 5 years after implant, well within industry standards. Ongoing data collection is needed to confirm longer-term performance of this family of ICD leads. PMID:28255544

Comparative study of LDR (Manchester system) and HDR image-guided conformal brachytherapy of cervical cancer: patterns of failure, late complications, and survival.

PubMed

Narayan, Kailash; van Dyk, Sylvia; Bernshaw, David; Rajasooriyar, Chrishanthi; Kondalsamy-Chennakesavan, Srinivas

2009-08-01

To compare patterns of failure, late toxicities, and survival in locally advanced cervical cancer patients treated by either low-dose-rate (LDR) or conformal high-dose-rate (HDRc) brachytherapy as a part of curative radiotherapy. A retrospective comparative study of 217 advanced cervix cancer patients was conducted; 90 of these patients received LDR and 127 received HDRc brachytherapy. All patients were staged using International Federation of Gynecology and Obstetrics (FIGO) rules, had pretreatment magnetic resonance imaging (MRI), and were treated with concurrent cisplatin chemoradiotherapy. Both groups matched for FIGO stage, MRI tumor volume, and uterine invasion status. Local and pelvic failures were similar 12-13% and 14% both in both groups. Abdominal and systemic failures in LDR group were 21% and 24%, whereas corresponding failures in HDRc group were 20% and 24%. Sixty-eight percent (87/127) of patients treated by HDRc remained asymptomatic, whereas 42% (38/90) of patients were asymptomatic from the bowel and bladder symptoms after treatment with LDR. The 5-year OS rate was 60% (SE = 4%). The 5-year failure-free survival rate was 55% (SE = 3%). There was no significant difference between the groups. Image-guided HDRc planning led to a large decrease in late radiation effects in patients treated by HDRc. Patterns of failure and survival were similar in patients treated either by LDR or HDRc.

A hazard and risk classification system for catastrophic rock slope failures in Norway

NASA Astrophysics Data System (ADS)

Hermanns, R.; Oppikofer, T.; Anda, E.; Blikra, L. H.; Böhme, M.; Bunkholt, H.; Dahle, H.; Devoli, G.; Eikenæs, O.; Fischer, L.; Harbitz, C. B.; Jaboyedoff, M.; Loew, S.; Yugsi Molina, F. X.

2012-04-01

The Geological Survey of Norway carries out systematic geologic mapping of potentially unstable rock slopes in Norway that can cause a catastrophic failure. As catastrophic failure we describe failures that involve substantial fragmentation of the rock mass during run-out and that impact an area larger than that of a rock fall (shadow angle of ca. 28-32° for rock falls). This includes therefore rock slope failures that lead to secondary effects, such as a displacement wave when impacting a water body or damming of a narrow valley. Our systematic mapping revealed more than 280 rock slopes with significant postglacial deformation, which might represent localities of large future rock slope failures. This large number necessitates prioritization of follow-up activities, such as more detailed investigations, periodic monitoring and permanent monitoring and early-warning. In the past hazard and risk were assessed qualitatively for some sites, however, in order to compare sites so that political and financial decisions can be taken, it was necessary to develop a quantitative hazard and risk classification system. A preliminary classification system was presented and discussed with an expert group of Norwegian and international experts and afterwards adapted following their recommendations. This contribution presents the concept of this final hazard and risk classification that should be used in Norway in the upcoming years. Historical experience and possible future rockslide scenarios in Norway indicate that hazard assessment of large rock slope failures must be scenario-based, because intensity of deformation and present displacement rates, as well as the geological structures activated by the sliding rock mass can vary significantly on a given slope. In addition, for each scenario the run-out of the rock mass has to be evaluated. This includes the secondary effects such as generation of displacement waves or landslide damming of valleys with the potential of later outburst floods. It became obvious that large rock slope failures cannot be evaluated on a slope scale with frequency analyses of historical and prehistorical events only, as multiple rockslides have occurred within one century on a single slope that prior to the recent failures had been inactive for several thousand years. In addition, a systematic analysis on temporal distribution indicates that rockslide activity following deglaciation after the Last Glacial Maximum has been much higher than throughout the Holocene. Therefore the classification system has to be based primarily on the geological conditions on the deforming slope and on the deformation rates and only to a lesser weight on a frequency analyses. Our hazard classification therefore is primarily based on several criteria: 1) Development of the back-scarp, 2) development of the lateral release surfaces, 3) development of the potential basal sliding surface, 4) morphologic expression of the basal sliding surface, 5) kinematic feasibility tests for different displacement mechanisms, 6) landslide displacement rates, 7) change of displacement rates (acceleration), 8) increase of rockfall activity on the unstable rock slope, 9) Presence post-glacial events of similar size along the affected slope and its vicinity. For each of these criteria several conditions are possible to choose from (e.g. different velocity classes for the displacement rate criterion). A score is assigned to each condition and the sum of all scores gives the total susceptibility score. Since many of these observations are somewhat uncertain, the classification system is organized in a decision tree where probabilities can be assigned to each condition. All possibilities in the decision tree are computed and the individual probabilities giving the same total score are summed. Basic statistics show the minimum and maximum total scores of a scenario, as well as the mean and modal value. The final output is a cumulative frequency distribution of the susceptibility scores that can be divided into several classes, which are interpreted as susceptibility classes (very high, high, medium, low, and very low). Today the Norwegian Planning and Building Act uses hazard classes with annual probabilities of impact on buildings producing damages (<1/100, <1/1000, <1/5000 and zero for critical buildings). However, up to now there is not enough scientific knowledge to predict large rock slope failures in these strict classes. Therefore, the susceptibility classes will be matched with the hazard classes from the Norwegian Building Act (e.g. very high susceptibility represents the hazard class with annual probability >1/100). The risk analysis focuses on the potential fatalities of a worst case rock slide scenario and its secondary effects only and is done in consequence classes with a decimal logarithmic scale. However we recommend for all high risk objects that municipalities carry out detailed risk analyses. Finally, the hazard and risk classification system will give recommendations where surveillance in form of continuous 24/7 monitoring systems coupled with early-warning systems (high risk class) or periodic monitoring (medium risk class) should be carried out. These measures are understood as to reduce the risk of life loss due to a rock slope failure close to 0 as population can be evacuated on time if a change of stability situation occurs. The final hazard and risk classification for all potentially unstable rock slopes in Norway, including all data used for its classification will be published within the national landslide database (available on www.skrednett.no).

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

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

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 failuremore » 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.« less

Comparison of mode of failure between primary and revision total knee arthroplasties.

PubMed

Liang, H; Bae, J K; Park, C H; Kim, K I; Bae, D K; Song, S J

2018-04-01

Cognizance of common reasons for failure in primary and revision TKA, together with their time course, facilitates prevention. However, there have been few reports specifically comparing modes of failure for primary vs. revision TKA using a single prosthesis. The goal of the study was to compare the survival rates, modes of failure, and time periods associated with each mode of failure, of primary vs. revision TKA. The survival rates, modes of failure, time period for each mode of failure, and risk factors would differ between primary and revision TKA. Data from a consecutive cohort comprising 1606 knees (1174 patients) of primary TKA patients, and 258 knees (224 patients) of revision TKA patients, in all of whom surgery involved a P.F.C ® prosthesis (Depuy, Johnson & Johnson, Warsaw, IN), was retrospectively reviewed. The mean follow-up periods of primary and revision TKAs were 9.2 and 9.8 years, respectively. The average 10- and 15-year survival rates for primary TKA were 96.7% (CI 95%,±0.7%) and 85.4% (CI 95%,±2.0%), and for revision TKA 91.4% (CI 95%,±2.5%) and 80.5% (CI 95%,±4.5%). Common modes of failure included polyethylene wear, loosening, and infection. The most common mode of failure was polyethylene wear in primary TKA, and infection in revision TKA. The mean periods (i.e., latencies) of polyethylene wear and loosening did not differ between primary and revision TKAs, but the mean period of infection was significantly longer for revision TKA (1.2 vs. 4.8 years, P=0.003). Survival rates decreased with time, particularly more than 10 years post-surgery, for both primary and revision TKAs. Continuous efforts are required to prevent and detect the various modes of failure during long-term follow-up. Greater attention is necessary to detect late infection-induced failure following revision TKA. Case-control study, Level III. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Microcircuit Device Reliability Memory/Digital LSI

DTIC Science & Technology

1982-01-01

has been performed. Each failure event record reveals the particular device and test characteristics, as well as associated stress values and other...given by: « s logio (Vxp) where X0 is the observed failure rate Xp is the predicted failure rate « is the residual Values of « are then plotted...n...... ||^||tpMMMWiWMM*i»""l’’൓ iŕŕ" ’• of failures per point). Some "funnelling" in Figure 17 shows this, although there is a fair amount of

Discharge clinical characteristics and 60-day readmission in patients hospitalized with heart failure.

PubMed

Anderson, Kelley M

2014-01-01

Heart failure is a clinical syndrome that incurs a high prevalence, mortality, morbidity, and economic burden in our society. Patients with heart failure may experience hospitalization because of an acute exacerbation of their condition. Recurrent hospitalizations soon after discharge are an unfortunate occurrence in this patient population. The purpose of this study was to explore the clinical and diagnostic characteristics of individuals hospitalized with a primary diagnosis of heart failure at the time of discharge and to compare the association of these indicators in individuals who did and did not experience a heart failure hospitalization within 60 days of the index stay. The study is a descriptive, correlational, quantitative study using a retrospective review of 134 individuals discharged with a primary diagnosis of heart failure. Records were reviewed for sociodemographic characteristics, health histories, clinical assessment findings, and diagnostic information. Significant predictors of 60-day heart failure readmissions were dyspnea (β = 0.579), crackles (β = 1.688), and assistance with activities of daily living (β = 2.328), independent of age, gender, and multiple other factors. By using hierarchical logistical regression, a model was derived that demonstrated the ability to correctly classify 77.4% of the cohort, 78.2% of those who did have a readmission (sensitivity of the prediction), and 76.7% of the subjects in whom the predicted event, readmission, did not occur (specificity of the prediction). Hospitalizations for heart failure are markers of clinical instability. Future events after hospitalization are common in this patient population, and this study provides a novel understanding of clinical characteristics at the time of discharge that are associated with future outcomes, specifically 60-day heart failure readmissions. A consideration of these characteristics provides an additional perspective to guide clinical decision making and the evaluation of discharge readiness.

24 CFR 902.62 - Failure to submit data.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 false Failure to submit data. 902.62... DEVELOPMENT PUBLIC HOUSING ASSESSMENT SYSTEM PHAS Scoring § 902.62 Failure to submit data. (a) Failure to... receive a presumptive rating of failure for its unaudited information and shall receive zero points for...

24 CFR 902.62 - Failure to submit data.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Failure to submit data. 902.62... DEVELOPMENT PUBLIC HOUSING ASSESSMENT SYSTEM PHAS Scoring § 902.62 Failure to submit data. (a) Failure to... receive a presumptive rating of failure for its unaudited information and shall receive zero points for...

24 CFR 902.62 - Failure to submit data.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Failure to submit data. 902.62... DEVELOPMENT PUBLIC HOUSING ASSESSMENT SYSTEM PHAS Scoring § 902.62 Failure to submit data. (a) Failure to... receive a presumptive rating of failure for its unaudited information and shall receive zero points for...

Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives.

PubMed

Sen, Ayan; Callisen, Hannelisa E; Alwardt, Cory M; Larson, Joel S; Lowell, Amelia A; Libricz, Stacy L; Tarwade, Pritee; Patel, Bhavesh M; Ramakrishna, Harish

2016-01-01

Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration.

Study of relapse and failure cases of CAT I retreated with CAT II under RNTCP--an eleven year follow up.

PubMed

Mehra, R K; Dhingra, V K; Nish, Aggarwal; Vashist, R P

2008-10-01

To analyse the treatment outcome of Cat I smear positive relapse and failure cases and their fate when treated with Cat II regimen under RNTCP. All Cat I smear positive relapse and failure TB patients treated with Category II regimen from 1994 to 2005 in a chest clinic of Delhi were analysed in this retrospective study. The re-treatment outcome data for relapse and failure cases of Cat I when treated with Cat II regimen was reviewed. The study population included 5576 registered as Cat I sputum positive cases in Gulabi Bagh chest clinic from 1994 to 2005. A total of 190 (3.4%) failed on Cat I regimen. Further out of 4905 (87.9%) successfully treated Cat I patients, 442 (9%) presented as relapses. The treatment success rate for relapse and failure cases of Cat I when subsequently treated with Cat II regimen were 76.4% and 48.8% respectively, with a significantly higher failure rate (27.6%) among Cat I failures subsequently treated with Cat II regimen. The failure cases of Cat I subsequently treated with Cat II were observed to have a significantly lower success rates (p < 0.05) as compared to relapse cases. The need for reappraisal of Cat II re-treatment regimen for failure cases among Cat I is suggested.

Stochastic Availability of a Repairable System with an Age - and Maintenance - Dependent Failure Rate,

DTIC Science & Technology

1982-06-01

STOCKATZC LV AaMIQ.YN 0gp M@lIm iii s m -r ANAs WgLMSZIb 940=04 WoeU-O PolytechnicInstitute June 1982 Stochastic Availability of a Repairable System ...STOCHASTIC AVAILABILITY OF A REPAIRABLE SYSTEM WITH AN AGE AND MAINTENANCE DEPENDENT FAILURE RATE by JACK-KANG CHAN June 1982 Report No..Poly EE/CS 82-004...1.1 Concepts of System Availability 1 1.2 Maintenance and Failure Rate 7 1.3 Summary Chapter 2 SYSTEM4 MODEL 2.1 A Repairable System with Lintenance

Accelerated Aging System for Prognostics of Power Semiconductor Devices

NASA Technical Reports Server (NTRS)

Celaya, Jose R.; Vashchenko, Vladislav; Wysocki, Philip; Saha, Sankalita

2010-01-01

Prognostics is an engineering discipline that focuses on estimation of the health state of a component and the prediction of its remaining useful life (RUL) before failure. Health state estimation is based on actual conditions and it is fundamental for the prediction of RUL under anticipated future usage. Failure of electronic devices is of great concern as future aircraft will see an increase of electronics to drive and control safety-critical equipment throughout the aircraft. Therefore, development of prognostics solutions for electronics is of key importance. This paper presents an accelerated aging system for gate-controlled power transistors. This system allows for the understanding of the effects of failure mechanisms, and the identification of leading indicators of failure which are essential in the development of physics-based degradation models and RUL prediction. In particular, this system isolates electrical overstress from thermal overstress. Also, this system allows for a precise control of internal temperatures, enabling the exploration of intrinsic failure mechanisms not related to the device packaging. By controlling the temperature within safe operation levels of the device, accelerated aging is induced by electrical overstress only, avoiding the generation of thermal cycles. The temperature is controlled by active thermal-electric units. Several electrical and thermal signals are measured in-situ and recorded for further analysis in the identification of leading indicators of failures. This system, therefore, provides a unique capability in the exploration of different failure mechanisms and the identification of precursors of failure that can be used to provide a health management solution for electronic devices.

Slow crack growth versus creep cavity coalescence: Competing failure mechanisms during high-temperature deformation of advanced ceramics

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

Jenkins, M.G.; Kohles, S.S.; Stevens, T.L.

1996-12-31

Duality of failure mechanisms (slow crack growth from pre-existing defects versus cumulative creep damage) is examined in a silicon nitride advanced ceramic recently tested at elevated-temperatures. Static (constant stress over time), dynamic (monotonically-increasing stress over time), and cyclic (fluctuating stress over time) fatigue behaviors were evaluated in tension in ambient air at temperatures of 1150, 1260, and 1370{degrees}C for a hot-isostatically pressed monolithic {beta}-silicon nitride. At 1150{degrees}C, all three types of fatigue results showed the similar failure mechanism of slow crack growth (SCG). At 1260 and 1370{degrees}C the failure mechanism was more complex. Failure under static fatigue was dominated bymore » the accumulation of creep damage via diffusion-controlled cavities. In dynamic fatigue, failure occurred by SCG at high stress rates (>10{sup {minus}2}MPa/s) and by creep damage at low stress rates ({le}10{sup {minus}2} MPa/s). For cyclic fatigue, such rate effects influenced the stress rupture results in which times to failure were greater for dynamic and cyclic fatigue than for static fatigue. Elucidation of failure mechanisms is necessary for accurate prediction of long-term survivability and reliability of structural ceramics.« less

Dialysis Arteriovenous Fistula Failure and Angioplasty: Intimal Hyperplasia and Other Causes of Access Failure.

PubMed

Duque, Juan C; Tabbara, Marwan; Martinez, Laisel; Cardona, Jose; Vazquez-Padron, Roberto I; Salman, Loay H

2017-01-01

The arteriovenous fistula (AVF) is the preferred hemodialysis access type because it has better patency rates and fewer complications than other access types. However, primary failure remains a common problem impeding AVF maturation and adding to patients' morbidity and mortality. Juxta-anastomotic (or inflow) stenosis is the most common reason leading to primary failure, and percutaneous transluminal angioplasty continues to be the gold-standard treatment with excellent success rates. Intimal hyperplasia (IH) has been traditionally blamed as the main pathophysiologic culprit, but new evidence raises doubts regarding the contribution of IH alone to primary failure. We report a 64-year-old man with a 2-stage brachiobasilic AVF that was complicated by failure 4 months after creation. An angiogram showed multiple juxta-anastomotic and midfistula stenotic lesions. Percutaneous transluminal angioplasty was successful in assisting maturation and subsequently cannulating the AVF for hemodialysis treatment. We failed to identify the underlying cause of stenosis because biopsy specimens from fistula tissue obtained at the time of transposition revealed no occlusive IH. This case emphasizes the need for additional research on factors contributing to AVF failure besides IH and highlights the need for more therapeutic options to reduce AVF failure rate. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Renewable energy for rural electrification in developing countries

NASA Astrophysics Data System (ADS)

Morgenstern, Joy

The environmental destruction caused by traditional methods of generating electricity and the environmental benefits of using renewable energy technologies are well-known. In additional to the environmental benefits, small, decentralized renewable energy systems are often the most economical way to electrify the rural areas of developing countries, where most of the world's unelectrified population lives. However, diffusion of these systems is proceeding very slowly and many of these projects have failed. This dissertation examines the hypothesis that an important determinant of the success of these projects is the extent to which they are compatible with the social and cultural attributes of the communities in which they are located. The hypothesis was examined by evaluating sixteen solar, wind and hybrid electrification projects in Mexico, using a procedure which rates projects according to criteria which reflect technical, economic and financial, environmental, and sociocultural factors deemed necessary to achieve success. Reasons for poor ratings within these criteria were then used to determine six preconditions for project success. The evaluation indicates that most of the wind and hybrid projects visited had low success ratings because of technical problems. The solar home system projects experienced few technical problems, yet many were unsuccessful. Most of the projects were unsustainable due to lack of financial resources, insufficient financial mechanisms, poor user training. In none of the communities were the projects economically viable, nor were they compatible with the needs of the users. The future success of even the most successful projects seen is doubtful because of the lack of provision for any maintenance by trained technicians and the scarcity of financial resources. A direct relationship between failure at the sociocultural criteria and overall project failure was not found. In most cases, failure at particular criteria could be attributed to the project developers' inability to fulfill social and cultural aspects of the preconditions for success, thus establishing an indirect but causal relationship between sociocultural attributes of communities and project success.

Material properties of rat middle cerebral arteries at high strain rates.

PubMed

Bell, E David; Converse, Matthew; Mao, Haojie; Unnikrishnan, Ginu; Reifman, Jaques; Monson, Kenneth L

2018-03-19

Traumatic brain injury (TBI), resulting from either impact- or non-impact blast-related mechanisms, is a devastating cause of death and disability. The cerebral blood vessels, which provide critical support for brain tissue in both health and disease, are commonly injured in TBI. However, little is known about how vessels respond to traumatic loading, particularly at rates relevant to blast. To better understand vessel responses to trauma, the objective of this project was to characterize the high-rate response of passive cerebral arteries. Rat middle cerebral arteries were isolated and subjected to high-rate deformation in the axial direction. Vessels were perfused at physiological pressures and stretched to failure at strain rates ranging from approximately 100 to 1300 s-1. Although both in vivo stiffness and failure stress increased significantly with strain rate, failure stretch did not depend on rate.

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

Fang, Aiman; Laguna, Ignacio; Sato, Kento

Future high-performance computing systems may face frequent failures with their rapid increase in scale and complexity. Resilience to faults has become a major challenge for large-scale applications running on supercomputers, which demands fault tolerance support for prevalent MPI applications. Among failure scenarios, process failures are one of the most severe issues as they usually lead to termination of applications. However, the widely used MPI implementations do not provide mechanisms for fault tolerance. We propose FTA-MPI (Fault Tolerance Assistant MPI), a programming model that provides support for failure detection, failure notification and recovery. Specifically, FTA-MPI exploits a try/catch model that enablesmore » failure localization and transparent recovery of process failures in MPI applications. We demonstrate FTA-MPI with synthetic applications and a molecular dynamics code CoMD, and show that FTA-MPI provides high programmability for users and enables convenient and flexible recovery of process failures.« less

Patterns of failure after involved field radiotherapy for locally advanced esophageal squamous cell carcinoma.

PubMed

Li, Duo-Jie; Li, Hong-Wei; He, Bin; Wang, Geng-Ming; Cai, Han-Fei; Duan, Shi-Miao; Liu, Jing-Jing; Zhang, Ya-Jun; Cui, Zhen; Jiang, Hao

2016-01-01

To retrospectively analyze the patterns of failure and the treatment effects of involved-field irradiation (IFI) on patients treated with locally advanced esophageal squamous cell carcinoma (ESCC) and to determine whether IFI is practicable in these patients. A total of 79 patients with locally advanced ESCC underwent three dimensional conformal (3D)CRT) or intensity modulated radiotherapy (IMRT) using IFI or elective nodal irradiation (ENI) according to the target volume. The patterns of failure were defined as local/regional, in-field, out)of)field regional lymph node (LN) and distant failure. With a median follow)up of 32.0 months, failures were observed in 66 (83.6%) patients. The cumulative incidence of local/regional failure (55.8 vs 52.8%) and in)field regional lymph node failure (25.6 vs 19.4%) showed no statistically significant difference between the IFI and the ENI group (p=0.526 and 0.215, respectively). Out)of)field nodal relapse rate of only 7.0% was seen in the IFI group. Three)year survival rates for the ENI and IFI group were 22.2 and 18.6%, respectively (p=0.240), and 3)year distant metastasis rates were 27.8 and 32.6%, respectively (p=0.180). The lung V10, V20, V30 and mean lung dose of the ENI group were greater than those of the IFI group, while the mean lung dose and V10 had statistically significant difference. The patterns of failure and survival rates in the IFI group were similar as in the ENI group; the regional recurrence and distant metastasis are the main cause of treatment failure. IFI is feasible for locally advanced ESCC. Further investigation is needed to increase local control and decrease distant metastasis in these patients.

Does an inter-flaw length control the accuracy of rupture forecasting in geological materials?

NASA Astrophysics Data System (ADS)

Vasseur, Jérémie; Wadsworth, Fabian B.; Heap, Michael J.; Main, Ian G.; Lavallée, Yan; Dingwell, Donald B.

2017-10-01

Multi-scale failure of porous materials is an important phenomenon in nature and in material physics - from controlled laboratory tests to rockbursts, landslides, volcanic eruptions and earthquakes. A key unsolved research question is how to accurately forecast the time of system-sized catastrophic failure, based on observations of precursory events such as acoustic emissions (AE) in laboratory samples, or, on a larger scale, small earthquakes. Until now, the length scale associated with precursory events has not been well quantified, resulting in forecasting tools that are often unreliable. Here we test the hypothesis that the accuracy of the forecast failure time depends on the inter-flaw distance in the starting material. We use new experimental datasets for the deformation of porous materials to infer the critical crack length at failure from a static damage mechanics model. The style of acceleration of AE rate prior to failure, and the accuracy of forecast failure time, both depend on whether the cracks can span the inter-flaw length or not. A smooth inverse power-law acceleration of AE rate to failure, and an accurate forecast, occurs when the cracks are sufficiently long to bridge pore spaces. When this is not the case, the predicted failure time is much less accurate and failure is preceded by an exponential AE rate trend. Finally, we provide a quantitative and pragmatic correction for the systematic error in the forecast failure time, valid for structurally isotropic porous materials, which could be tested against larger-scale natural failure events, with suitable scaling for the relevant inter-flaw distances.

Analysis of the Factors Affecting Surgical Success of Implants Placed in Iranian Warfare Victims

PubMed Central

Jafarian, Mohammad; Bayat, Mohammad; Pakravan, Amir-Hossein; Emadi, Naghmeh

2016-01-01

Objective The aim was to evaluate the survival time and success rates of dental implants in warfare victims and factors that affect implant success. Subjects and Methods This retrospective study involved 250 Iranian warfare victims who received dental implants from 2003 to 2013. Patients' demographic characteristics, as well as the brand, diameter, length, location and failure rate of the implants were retrieved from patients' dental records and radiographs. The associations between these data and the survival rate were analyzed. Statistical analysis was carried out with χ2 and log-rank tests. Results Overall, out of the 1,533 dental implants, 61 (4s%) failed. The maxillary canine area had the highest failure rate [9 of 132 implants (6.8s%)], while the mandibular incisor region had the least number of failures [3 of 147 implants (2.0s%)] and the longest survival time (approximately 3,182 days). Maxillary canine areas had the shortest survival (about 2,996 days). The longest survival time was observed in implants with 11 mm length (3,179.72 ± 30.139 days) and 3.75-4 mm diameter (3,131.161 ± 35.96 days), and the shortest survival was found in implants with 11.5 mm length (2,317.79 ± 18.71 days) and 6.5 mm diameter (2,241.45 ± 182.21 days). Moreover, implants with 10 mm length (10.7s%) and 5.5-6 mm diameter (22.2s%) had the highest failure rate; however, the least failure rate occurred when the implants were 11.5 mm in length (1.9s%) and 3-3.5 mm in diameter (3.1s%). Conclusions The brand, length and diameter of implants affected the survival time, failure rate and time to failure. The location of the implant was not statistically significant regarding the mentioned factors, although it has clinical significance. PMID:27322534

Improving the retrieval rate of inferior vena cava filters with a multidisciplinary team approach

PubMed Central

Inagaki, Elica; Farber, Alik; Eslami, Mohammad H.; Siracuse, Jeffrey J.; Rybin, Denis V.; Sarosiek, Shayna; Sloan, J. Mark; Kalish, Jeffrey

2017-01-01

Objective The option to retrieve inferior vena cava (IVC) filters has resulted in an increase in the utilization of these devices as stopgap measures in patients with relative contraindications to anticoagulation. These retrievable IVC filters, however, are often not retrieved and become permanent. Recent data from our institution confirmed a historically low retrieval rate. Therefore, we hypothesized that the implementation of a new IVC filter retrieval protocol would increase the retrieval rate of appropriate IVC filters at our institution. Methods All consecutive patients who underwent an IVC filter placement at our institution between September 2003 and July 2012 were retrospectively reviewed. In August 2012, a multidisciplinary task force was established, and a new IVC filter retrieval protocol was implemented. Prospective data were collected using a centralized interdepartmental IVC filter registry for all consecutive patients who underwent an IVC filter placement between August 2012 and September 2014. Patients were chronologically categorized into preimplementation (PRE) and postimplementation (POST) groups. Comparisons of outcome measures, including the retrieval rate of IVC filters along with rates of retrieval attempt and technical failure, were made between the two groups. Results In the PRE and POST groups, a total of 720 and 74 retrievable IVC filters were implanted, respectively. In the POST group, 40 of 74 filters (54%) were successfully retrieved compared with 82 of 720 filters (11%) in the PRE group (P < .001). Furthermore, a greater number of IVC filter retrievals were attempted in the POST group than in the PRE group (66% vs 14%; P < .001). No significant difference was observed between the PRE and POST groups for technical failure (17% vs 18%; P = .9). Conclusions The retrieval rate of retrievable IVC filters at our institution was significantly increased with the implementation of a new IVC filter retrieval protocol with a multidisciplinary team approach. This improved retrieval rate is possible with minimal dedication of resources and can potentially lead to a decrease in IVC filter-related complications in the future. PMID:27318045

ISS Ammonia Pump Failure, Recovery, and Lesson Learned A Hydrodynamic Bearing Perspective

NASA Technical Reports Server (NTRS)

Bruckner, Robert J.; Manco, Richard A., II

2014-01-01

The design, development, and operation of long duration spaceflight hardware has become an evolutionary process in which meticulous attention to details and lessons learned from previous experiences play a critical role. Invaluable to this process is the ability to retrieve and examine spaceflight hardware that has experienced a premature failure. While these situations are rare and unfortunate, the failure investigation and recovery from the event serve a valuable purpose in advancing future space mechanism development. Such a scenario began on July 31, 2010 with the premature failure of an ammonia pump on the external active thermal control system of the International Space Station. The ground-based inspections of the returned pump and ensuing failure investigation revealed five potential bearing forces that were un-accounted for in the design phase and qualification testing of the pump. These forces could combine in a number of random orientations to overload the pump bearings leading to solid-surface contact, wear, and premature failure. The recovery plan identified one of these five forces as being related to the square of the operating speed of the pump and this fact was used to recover design life through a change in flight rules for the operation of the pump module. Through the course of the failure investigation, recovery, and follow-on assessment of pump wear life, design guidance has been developed to improve the life of future mechanically pumped thermal control systems for both human and robotic exploration missions.

A risk-based approach to sanitary sewer pipe asset management.

PubMed

Baah, Kelly; Dubey, Brajesh; Harvey, Richard; McBean, Edward

2015-02-01

Wastewater collection systems are an important component of proper management of wastewater to prevent environmental and human health implications from mismanagement of anthropogenic waste. Due to aging and inadequate asset management practices, the wastewater collection assets of many cities around the globe are in a state of rapid decline and in need of urgent attention. Risk management is a tool which can help prioritize resources to better manage and rehabilitate wastewater collection systems. In this study, a risk matrix and a weighted sum multi-criteria decision-matrix are used to assess the consequence and risk of sewer pipe failure for a mid-sized city, using ArcGIS. The methodology shows that six percent of the uninspected sewer pipe assets of the case study have a high consequence of failure while four percent of the assets have a high risk of failure and hence provide priorities for inspection. A map incorporating risk of sewer pipe failure and consequence is developed to facilitate future planning, rehabilitation and maintenance programs. The consequence of failure assessment also includes a novel failure impact factor which captures the effect of structurally defective stormwater pipes on the failure assessment. The methodology recommended in this study can serve as a basis for future planning and decision making and has the potential to be universally applied by municipal sewer pipe asset managers globally to effectively manage the sanitary sewer pipe infrastructure within their jurisdiction. Copyright © 2014 Elsevier B.V. All rights reserved.

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

PubMed

Doggrell, Sheila Anne; Schaffer, Sally

2016-02-01

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

Assessment of heart rate, acidosis, consciousness, oxygenation, and respiratory rate to predict noninvasive ventilation failure in hypoxemic patients.

PubMed

Duan, Jun; Han, Xiaoli; Bai, Linfu; Zhou, Lintong; Huang, Shicong

2017-02-01

To develop and validate a scale using variables easily obtained at the bedside for prediction of failure of noninvasive ventilation (NIV) in hypoxemic patients. The test cohort comprised 449 patients with hypoxemia who were receiving NIV. This cohort was used to develop a scale that considers heart rate, acidosis, consciousness, oxygenation, and respiratory rate (referred to as the HACOR scale) to predict NIV failure, defined as need for intubation after NIV intervention. The highest possible score was 25 points. To validate the scale, a separate group of 358 hypoxemic patients were enrolled in the validation cohort. The failure rate of NIV was 47.8 and 39.4% in the test and validation cohorts, respectively. In the test cohort, patients with NIV failure had higher HACOR scores at initiation and after 1, 12, 24, and 48 h of NIV than those with successful NIV. At 1 h of NIV the area under the receiver operating characteristic curve was 0.88, showing good predictive power for NIV failure. Using 5 points as the cutoff value, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for NIV failure were 72.6, 90.2, 87.2, 78.1, and 81.8%, respectively. These results were confirmed in the validation cohort. Moreover, the diagnostic accuracy for NIV failure exceeded 80% in subgroups classified by diagnosis, age, or disease severity and also at 1, 12, 24, and 48 h of NIV. Among patients with NIV failure with a HACOR score of >5 at 1 h of NIV, hospital mortality was lower in those who received intubation at ≤12 h of NIV than in those intubated later [58/88 (66%) vs. 138/175 (79%); p = 0.03). The HACOR scale variables are easily obtained at the bedside. The scale appears to be an effective way of predicting NIV failure in hypoxemic patients. Early intubation in high-risk patients may reduce hospital mortality.

Heart failure rehospitalization of the Medicare FFS patient: a state-level analysis exploring 30-day readmission factors.

PubMed

Schmeida, Mary; Savrin, Ronald A

2012-01-01

Heart failure readmission among the elderly is frequent and costly to both the patient and the Medicare trust fund. In this study, the authors explore the factors that are associated with states having heart failure readmission rates that are higher than the U.S. national rate. Acute inpatient hospital settings. 50 state-level data and multivariate regression analysis is used. The dependent variable Heart Failure 30-day Readmission Worse than U.S. Rate is based on adult Medicare Fee-for-Service patients hospitalized with a primary discharge diagnosis of heart failure and for which a subsequent inpatient readmission occurred within 30 days of their last discharge. One key variable found--states with a higher resident population speaking a primary language other than English at home--that is significantly associated with a decrease in probability in states ranking "worse" on heart failure 30-day readmission. Whereas, states with a higher median income, more total days of care per 1,000 Medicare enrollees, and a greater percentage of Medicare enrollees with prescription drug coverage have a greater probability for heart failure 30-day readmission to be "worse" than the U.S. national rate. Case management interventions targeting health literacy may be more effective than other factors to improve state-level hospital status on heart failure 30-day readmission. Factors such as total days of care per 1,000 Medicare enrollees and improving patient access to postdischarge medication(s) may not be as important as literacy. Interventions aimed to prevent disparities should consider higher income population groups as vulnerable for readmission.

The Syncardia™ total artificial heart: in vivo, in vitro, and computational modeling studies

PubMed Central

Slepian, Marvin J.; Alemu, Yared; Soares, João Silva; Smith, Richard G.; Einav, Shmuel; Bluestein, Danny

2014-01-01

The SynCardia™ total artificial heart (TAH) is the only FDA-approved TAH in the world. The SynCardia™ TAH is a pneumatically driven, pulsatile system capable of flows of >9 L/min. The TAH is indicated for use as a bridge to transplantation (BTT) in patients at imminent risk of death from non-reversible bi-ventricular failure. In the Pivotal US approval trial the TAH achieved a BTT rate of >79%. Recently a multi-center, post-market approval study similarly demonstrated a comparable BTT rate. A major milestone was recently achieved for the TAH, with over 1100 TAHs having been implanted to date, with the bulk of implantation occurring at an ever increasing rate in the past few years. The TAH is most commonly utilized to save the lives of patients dying from end-stage bi-ventricular heart failure associated with ischemic or non-ischemic dilated cardiomyopathy. Beyond progressive chronic heart failure, the TAH has demonstrated great efficacy in supporting patients with acute irreversible heart failure associated with massive acute myocardial infarction. In recent years several diverse clinical scenarios have also proven to be well served by the TAH including severe heart failure associated with advanced congenital heart disease. failed or burned-out transplants, infiltrative and restrictive cardiomyopathies and failed ventricular assist devices. Looking to the future a major unmet need remains in providing total heart support for children and small adults. As such, the present TAH design must be scaled to fit the smaller patient, while providing equivalent, if not superior flow characteristics, shear profiles and overall device thrombogenicity. To aid in the development of a new “pediatric,” TAH an engineering methodology known as “Device Thrombogenicity Emulation (DTE)”, that we have recently developed and described, is being employed. Recently, to further our engineering understanding of the TAH, as steps towards next generation designs we have: (1) assessed of the degree of platelet reactivity induced by the present clinical 70 cc TAH using a closed loop platelet activity state assay, (2) modeled the motion of the TAH pulsatile mobile diaphragm, and (3) performed fluid-structure interactions and assessment of the flow behavior through inflow and outflow regions of the TAH fitted with modern bi-leaflet heart valves. Developing a range of TAH devices will afford biventricular replacement therapy to a wide range of patients, for both short and long-term therapy. PMID:23305813

Syndromic surveillance for health information system failures: a feasibility study

PubMed Central

Ong, Mei-Sing; Magrabi, Farah; Coiera, Enrico

2013-01-01

Objective To explore the applicability of a syndromic surveillance method to the early detection of health information technology (HIT) system failures. Methods A syndromic surveillance system was developed to monitor a laboratory information system at a tertiary hospital. Four indices were monitored: (1) total laboratory records being created; (2) total records with missing results; (3) average serum potassium results; and (4) total duplicated tests on a patient. The goal was to detect HIT system failures causing: data loss at the record level; data loss at the field level; erroneous data; and unintended duplication of data. Time-series models of the indices were constructed, and statistical process control charts were used to detect unexpected behaviors. The ability of the models to detect HIT system failures was evaluated using simulated failures, each lasting for 24 h, with error rates ranging from 1% to 35%. Results In detecting data loss at the record level, the model achieved a sensitivity of 0.26 when the simulated error rate was 1%, while maintaining a specificity of 0.98. Detection performance improved with increasing error rates, achieving a perfect sensitivity when the error rate was 35%. In the detection of missing results, erroneous serum potassium results and unintended repetition of tests, perfect sensitivity was attained when the error rate was as small as 5%. Decreasing the error rate to 1% resulted in a drop in sensitivity to 0.65–0.85. Conclusions Syndromic surveillance methods can potentially be applied to monitor HIT systems, to facilitate the early detection of failures. PMID:23184193

Patterns of recurrence after trimodality therapy for esophageal cancer.

PubMed

Dorth, Jennifer A; Pura, John A; Palta, Manisha; Willett, Christopher G; Uronis, Hope E; D'Amico, Thomas A; Czito, Brian G

2014-07-15

Patterns of failure after neoadjuvant chemoradiotherapy and surgery for esophageal cancer are poorly defined. All patients in the current study were treated with trimodality therapy for nonmetastatic esophageal cancer from 1995 to 2009. Locoregional failure included lymph node failure (NF), anastomotic failure, or both. Abdominal paraaortic failure (PAF) was defined as disease recurrence at or below the superior mesenteric artery. Among 155 patients, the primary tumor location was the upper/middle esophagus in 18%, the lower esophagus in 32%, and the gastroesophageal junction in 50% (adenocarcinoma in 79% and squamous cell carcinoma in 21%) of patients. Staging methods included endoscopic ultrasound (73%), computed tomography (46%), and positron emission tomography/computed tomography (54%). Approximately 40% of patients had American Joint Committee on Cancer stage II disease and 60% had stage III disease. The median follow-up was 1.3 years. The 2-year locoregional control, event-free survival, and overall survival rates were 86%, 36%, and 48%, respectively. The 2-year NF rate was 14%, the isolated NF rate was 3%, and the anastomotic failure rate was 6%. The 2-year PAF rate was 9% and the isolated PAF rate was 5%. PAF was found to be increased among patients with gastroesophageal junction tumors (12% vs 6%), especially for the subset with ≥ 2 clinically involved lymph nodes at the time of diagnosis (19% vs 4%). Few patients experience isolated NF or PAF as their first disease recurrence. Therefore, it is unlikely that targeting additional regional lymph node basins with radiotherapy would significantly improve clinical outcomes. © 2014 American Cancer Society.

[Assessment of medical management of heart failure at National Hospital Blaise COMPAORE].

PubMed

Kambiré, Y; Konaté, L; Diallo, I; Millogo, G R C; Kologo, K J; Tougouma, J B; Samadoulougou, A K; Zabsonré, P

2018-05-09

The aim of this study was to assess the quality of medical management of heart failure at the National Hospital Blaise Compaoré according to the international guidelines. A retrospective study was performed including consecutive patients admitted for heart failure documented sonographically from October 2012 to March 2015 in the Medicine and Medical Specialties Department of National Hospital Blaise Compaore with a minimum follow-up of six weeks. Data analysis was made by the SPSS 20.0 software. Eighty-four patients, mean age of 57.61±18.24 years, were included. It was an acute heart failure in 84.5% of patients with systolic left ventricular function impaired (77.4%). The rate of prescription of different drugs in heart failure any type was 88.1% for loop diuretics; 77.1% for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and 65.5% for betablockers. In patients with systolic dysfunction, 84.62% of patients were received the combination of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and 75.38% for betablockers. Exercise rehabilitation was undergoing in 10.7% of patients. The death rate was 16.7% and hospital readmission rate of 16.7%. The prescription rate of major heart failure drugs is satisfactory. Cardiac rehabilitation should be developed. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

[Frequency, etiology, and outcomes of acute renal failure (data of Kaunas University of Medicine Hospital in 1995-2006)].

PubMed

Skarupskiene, Inga; Kuzminskis, Vytautas; Ziginskiene, Edita

2007-01-01

The aim of this study was to determine the frequency, etiology, and outcomes of acute renal failure. We retrospectively collected data on all patients (n=1653) who received renal replacement therapy for acute renal failure at the Kaunas University of Medicine Hospital during 1995-2006. The number of patients with acute renal failure increased nine times during the 11-year period. The mean age of patients was 59.76+/-17.52 years and increased from 44.97+/-17.1 years in 1995 to 62.84+/-16.49 years in 2006. The most common causes of acute renal failure were renal (n=646, 39%), prerenal (n=380, 23%), and obstructive (n=145, 9%). The renal replacement therapy was discontinued because of recovery of renal function in 49.9% of cases. The overall hospital mortality rate was 45.1%. Renal function did not recover in 6.7% of patients. The mortality rate over the 11-year period varied from 37.8 to 57.5%. The highest mortality rate was in the neurosurgical (62.3%) and cardiac surgical (61.8%) intensive care units. High mortality rate (more than 50%) was in the groups of patients with acute renal failure that was caused by hepatorenal syndrome, shock, sepsis, and reduced cardiac output.

PREDICE score as a predictor of 90 days mortality in patients with heart failure

NASA Astrophysics Data System (ADS)

Purba, D. P. S.; Hasan, R.

2018-03-01

Hospitalization in chronic heart failure patients associated with high mortality and morbidity rate. The 90 days post-discharge period following hospitalization in heart failure patients is known as the vulnerable phase, it carries the high risk of poor outcomes. Identification of high-risk individuals by using prognostic evaluation was intended to do a closer follow up and more intensive to decreasing the morbidity and mortality rate of heart failure.To determine whether PREDICE score could predict mortality within 90 days in patients with heart failure, an observational cohort study in patients with heart failure who were hospitalized due to worsening chronic heart failure. Patients were in following-up for up to 90 days after initial evaluation with the primary endpoint is death.We found a difference of the significantstatistical between PREDICE score in survival and mortality group (p=0.001) of 84% (95% CI: 60.9% - 97.4%).In conclusion, PREDICE score has a good ability to predict mortality within 90 days in patients with heart failure.

Implantable Hemodynamic Monitoring for Heart Failure Patients.

PubMed

Abraham, William T; Perl, Leor

2017-07-18

Rates of heart failure hospitalization remain unacceptably high. Such hospitalizations are associated with substantial patient, caregiver, and economic costs. Randomized controlled trials of noninvasive telemedical systems have failed to demonstrate reduced rates of hospitalization. The failure of these technologies may be due to the limitations of the signals measured. Intracardiac and pulmonary artery pressure-guided management has become a focus of hospitalization reduction in heart failure. Early studies using implantable hemodynamic monitors demonstrated the potential of pressure-based heart failure management, whereas subsequent studies confirmed the clinical utility of this approach. One large pivotal trial proved the safety and efficacy of pulmonary artery pressure-guided heart failure management, showing a marked reduction in heart failure hospitalizations in patients randomized to active pressure-guided management. "Next-generation" implantable hemodynamic monitors are in development, and novel approaches for the use of this data promise to expand the use of pressure-guided heart failure management. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Reliability analysis and fault-tolerant system development for a redundant strapdown inertial measurement unit. [inertial platforms

NASA Technical Reports Server (NTRS)

Motyka, P.

1983-01-01

A methodology is developed and applied for quantitatively analyzing the reliability of a dual, fail-operational redundant strapdown inertial measurement unit (RSDIMU). A Markov evaluation model is defined in terms of the operational states of the RSDIMU to predict system reliability. A 27 state model is defined based upon a candidate redundancy management system which can detect and isolate a spectrum of failure magnitudes. The results of parametric studies are presented which show the effect on reliability of the gyro failure rate, both the gyro and accelerometer failure rates together, false alarms, probability of failure detection, probability of failure isolation, and probability of damage effects and mission time. A technique is developed and evaluated for generating dynamic thresholds for detecting and isolating failures of the dual, separated IMU. Special emphasis is given to the detection of multiple, nonconcurrent failures. Digital simulation time histories are presented which show the thresholds obtained and their effectiveness in detecting and isolating sensor failures.

Prospective trial of angiography and embolization for all grade III to V blunt splenic injuries: nonoperative management success rate is significantly improved.

PubMed

Miller, Preston R; Chang, Michael C; Hoth, J Jason; Mowery, Nathan T; Hildreth, Amy N; Martin, R Shayn; Holmes, James H; Meredith, J Wayne; Requarth, Jay A

2014-04-01

Nonoperative management (NOM) of blunt splenic injury is well accepted. Substantial failure rates in higher injury grades remain common, with one large study reporting rates of 19.6%, 33.3%, and 75% for grades III, IV, and V, respectively. Retrospective data show angiography and embolization can increase salvage rates in these severe injuries. We developed a protocol requiring referral of all blunt splenic injuries, grades III to V, without indication for immediate operation for angiography and embolization. We hypothesized that angiography and embolization of high-grade blunt splenic injury would reduce NOM failure rates in this population. This was a prospective study at our Level I trauma center as part of a performance-improvement project. Demographics, injury characteristics, and outcomes were compared with historic controls. The protocol required all stable patients with grade III to V splenic injuries be referred for angiography and embolization. In historic controls, referral was based on surgeon preference. From January 1, 2010 to December 31, 2012, there were 168 patients with grades III to V spleen injuries admitted; NOM was undertaken in 113 (67%) patients. The protocol was followed in 97 patients, with a failure rate of 5%. Failure rate in the 16 protocol deviations was 25% (p = 0.02). Historic controls from January 1, 2007 to December 31, 2009 were compared with the protocol group. One hundred and fifty-three patients with grade III to V injuries were admitted during this period, 80 (52%) patients underwent attempted NOM. Failure rate was significantly higher than for the protocol group (15%, p = 0.04). Use of a protocol requiring angiography and embolization for all high-grade spleen injuries slated for NOM leads to a significantly decreased failure rate. We recommend angiography and embolization as an adjunct to NOM for all grade III to V splenic injuries. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Ceramic capacitor insulation resistance failures accelerated by low voltage

NASA Technical Reports Server (NTRS)

Brennan, T. F.

1978-01-01

Ceramic capacitors failed insulation resistance testing at less than one-tenth their rated voltage. Many failures recovered as the voltage was increased. Comprehensive failure analysis techniques, some of which are unprecedented, were used to examine these failures. It was determined that there was more than one failure mechanism, and the results indicate a need for special additional screening.

Inattention in primary school is not good for your future school achievement—A pattern classification study

PubMed Central

Bøe, Tormod; Lundervold, Arvid

2017-01-01

Inattention in childhood is associated with academic problems later in life. The contribution of specific aspects of inattentive behaviour is, however, less known. We investigated feature importance of primary school teachers’ reports on nine aspects of inattentive behaviour, gender and age in predicting future academic achievement. Primary school teachers of n = 2491 children (7–9 years) rated nine items reflecting different aspects of inattentive behaviour in 2002. A mean academic achievement score from the previous semester in high school (2012) was available for each youth from an official school register. All scores were at a categorical level. Feature importances were assessed by using multinominal logistic regression, classification and regression trees analysis, and a random forest algorithm. Finally, a comprehensive pattern classification procedure using k-fold cross-validation was implemented. Overall, inattention was rated as more severe in boys, who also obtained lower academic achievement scores in high school than girls. Problems related to sustained attention and distractibility were together with age and gender defined as the most important features to predict future achievement scores. Using these four features as input to a collection of classifiers employing k-fold cross-validation for prediction of academic achievement level, we obtained classification accuracy, precision and recall that were clearly better than chance levels. Primary school teachers’ reports of problems related to sustained attention and distractibility were identified as the two most important features of inattentive behaviour predicting academic achievement in high school. Identification and follow-up procedures of primary school children showing these characteristics should be prioritised to prevent future academic failure. PMID:29182663

Inattention in primary school is not good for your future school achievement-A pattern classification study.

PubMed

Lundervold, Astri J; Bøe, Tormod; Lundervold, Arvid

2017-01-01

Inattention in childhood is associated with academic problems later in life. The contribution of specific aspects of inattentive behaviour is, however, less known. We investigated feature importance of primary school teachers' reports on nine aspects of inattentive behaviour, gender and age in predicting future academic achievement. Primary school teachers of n = 2491 children (7-9 years) rated nine items reflecting different aspects of inattentive behaviour in 2002. A mean academic achievement score from the previous semester in high school (2012) was available for each youth from an official school register. All scores were at a categorical level. Feature importances were assessed by using multinominal logistic regression, classification and regression trees analysis, and a random forest algorithm. Finally, a comprehensive pattern classification procedure using k-fold cross-validation was implemented. Overall, inattention was rated as more severe in boys, who also obtained lower academic achievement scores in high school than girls. Problems related to sustained attention and distractibility were together with age and gender defined as the most important features to predict future achievement scores. Using these four features as input to a collection of classifiers employing k-fold cross-validation for prediction of academic achievement level, we obtained classification accuracy, precision and recall that were clearly better than chance levels. Primary school teachers' reports of problems related to sustained attention and distractibility were identified as the two most important features of inattentive behaviour predicting academic achievement in high school. Identification and follow-up procedures of primary school children showing these characteristics should be prioritised to prevent future academic failure.

Bending spring rate investigation of nanopipette for cell injection.

PubMed

Shen, Yajing; Zhang, Zhenhai; Fukuda, Toshio

2015-04-17

Bending of nanopipette tips during cell penetration is a major cause of cell injection failure. However, the flexural rigidity of nanopipettes is little known due to their irregular structure. In this paper, we report a quantitative method to estimate the flexural rigidity of a nanopipette by investigating its bending spring rate. First nanopipettes with a tip size of 300 nm are fabricated from various glass tubes by laser pulling followed by focused ion beam (FIB) milling. Then the bending spring rate of the nanopipettes is investigated inside a scanning electron microscope (SEM). Finally, a yeast cell penetration test is performed on these nanopipettes, which have different bending spring rates. The results show that nanopipettes with a higher bending spring rate have better cell penetration capability, which confirms that the bending spring rate may well reflect the flexural rigidity of a nanopipette. This method provides a quantitative parameter for characterizing the mechanical property of a nanopipette that can be potentially taken as a standard specification in the future. This general method can also be used to estimate other one-dimensional structures for cell injection, which will greatly benefit basic cell biology research and clinical applications.

Bending spring rate investigation of nanopipette for cell injection

NASA Astrophysics Data System (ADS)

Shen, Yajing; Zhang, Zhenhai; Fukuda, Toshio

2015-04-01

Bending of nanopipette tips during cell penetration is a major cause of cell injection failure. However, the flexural rigidity of nanopipettes is little known due to their irregular structure. In this paper, we report a quantitative method to estimate the flexural rigidity of a nanopipette by investigating its bending spring rate. First nanopipettes with a tip size of 300 nm are fabricated from various glass tubes by laser pulling followed by focused ion beam (FIB) milling. Then the bending spring rate of the nanopipettes is investigated inside a scanning electron microscope (SEM). Finally, a yeast cell penetration test is performed on these nanopipettes, which have different bending spring rates. The results show that nanopipettes with a higher bending spring rate have better cell penetration capability, which confirms that the bending spring rate may well reflect the flexural rigidity of a nanopipette. This method provides a quantitative parameter for characterizing the mechanical property of a nanopipette that can be potentially taken as a standard specification in the future. This general method can also be used to estimate other one-dimensional structures for cell injection, which will greatly benefit basic cell biology research and clinical applications.

Investigation of International Space Station Major Constituent Analyzer Anomalous ORU 02 Performance

NASA Technical Reports Server (NTRS)

Gardner, Ben D.; Burchfield, David E.; Pargellis, Andrew; Erwin, Phillip M.; Thoresen, Souzan; Gentry, Grey; Granahan, John; Matty, Chris

2013-01-01

The Major Constituent Analyzer (MCA) is a mass spectrometer based system that measures the major atmospheric constituents on the International Space Station. In 2011, two MCA ORU 02 analyzer assemblies experienced premature on-orbit failures. These failures were determined to be the result of off-nominal ion source filament performance. Recent product improvements to ORU 02 designed to improve the lifetime of the ion pump also constrained the allowable tuning criteria for the ion source filaments. This presentation describes the filament failures as well as the corrective actions implemented to preclude such failures in the future.

Development Testing and Subsequent Failure Investigation of a Spring Strut Mechanism

NASA Technical Reports Server (NTRS)

Dervan, Jared; Robertson, Brandan; Staab, Lucas; Culberson, Michael; Pellicciotti, Joseph

2014-01-01

The NASA Engineering and Safety Center (NESC) and Lockheed Martin (LM) performed random vibration testing on a single spring strut development unit to assess its ability to withstand qualification level random vibration environments. Failure of the strut while exposed to random vibration resulted in a follow-on failure investigation, design changes, and additional development tests. This paper focuses on the results of the failure investigations referenced in detail in the NESC final report [1] including identified lessons learned to aid in future design iterations of the spring strut and to help other mechanism developers avoid similar pitfalls.

Development Testing and Subsequent Failure Investigation of a Spring Strut Mechanism

NASA Technical Reports Server (NTRS)

Dervan, Jared; Robertson, Brandon; Staab, Lucas; Culberson, Michael; Pellicciotti, Joseph

2014-01-01

The NASA Engineering and Safety Center (NESC) and Lockheed Martin (LM) performed random vibration testing on a single spring strut development unit to assess its ability to withstand qualification level random vibration environments. Failure of the strut while exposed to random vibration resulted in a follow-on failure investigation, design changes, and additional development tests. This paper focuses on the results of the failure investigations referenced in detail in the NESC final report including identified lessons learned to aid in future design iterations of the spring strut and to help other mechanism developers avoid similar pitfalls.

Heart Failure: From Research to Clinical Practice.

PubMed

Islam, Md Shahidul

2018-01-01

"Heart failure: from research to clinical practice", a collection of selected reviews, which comes out also as a book, covers essentially all important aspects of heart failure, including the pathogenesis, clinical features, biomarkers, imaging techniques, medical treatment and surgical treatments, use of pacemakers and implantable cardioverter defibrillators, and palliative care. The reviews include essential background information, state of the art, critical and in-depth analysis, and directions for future researches for elucidation of the unresolved issues. Everyone interested in heart failure is expected to find this compilation helpful for a deeper understanding of some of the complex issues.

Matrix Dominated Failure of Fiber-Reinforced Composite Laminates Under Static and Dynamic Loading

NASA Astrophysics Data System (ADS)

Schaefer, Joseph Daniel

Hierarchical material systems provide the unique opportunity to connect material knowledge to solving specific design challenges. Representing the quickest growing class of hierarchical materials in use, fiber-reinforced polymer composites (FRPCs) offer superior strength and stiffness-to-weight ratios, damage tolerance, and decreasing production costs compared to metals and alloys. However, the implementation of FRPCs has historically been fraught with inadequate knowledge of the material failure behavior due to incomplete verification of recent computational constitutive models and improper (or non-existent) experimental validation, which has severely slowed creation and development. Noted by the recent Materials Genome Initiative and the Worldwide Failure Exercise, current state of the art qualification programs endure a 20 year gap between material conceptualization and implementation due to the lack of effective partnership between computational coding (simulation) and experimental characterization. Qualification processes are primarily experiment driven; the anisotropic nature of composites predisposes matrix-dominant properties to be sensitive to strain rate, which necessitates extensive testing. To decrease the qualification time, a framework that practically combines theoretical prediction of material failure with limited experimental validation is required. In this work, the Northwestern Failure Theory (NU Theory) for composite lamina is presented as the theoretical basis from which the failure of unidirectional and multidirectional composite laminates is investigated. From an initial experimental characterization of basic lamina properties, the NU Theory is employed to predict the matrix-dependent failure of composites under any state of biaxial stress from quasi-static to 1000 s-1 strain rates. It was found that the number of experiments required to characterize the strain-rate-dependent failure of a new composite material was reduced by an order of magnitude, and the resulting strain-rate-dependence was applicable for a large class of materials. The presented framework provides engineers with the capability to quickly identify fiber and matrix combinations for a given application and determine the failure behavior over the range of practical loadings cases. The failure-mode-based NU Theory may be especially useful when partnered with computational approaches (which often employ micromechanics to determine constituent and constitutive response) to provide accurate validation of the matrix-dominated failure modes experienced by laminates during progressive failure.

Left ventricular ejection time is an independent predictor of incident heart failure in a community-based cohort.

PubMed

Biering-Sørensen, Tor; Querejeta Roca, Gabriela; Hegde, Sheila M; Shah, Amil M; Claggett, Brian; Mosley, Thomas H; Butler, Kenneth R; Solomon, Scott D

2017-09-04

Systolic time intervals change in the progress of cardiac dysfunction. The usefulness of left ventricular ejection time (LVET) to predict cardiovascular morbidity, however, is unknown. We studied middle-aged African-Americans from one of four cohorts of the Atherosclerosis Risk in Communities study (Jackson cohort, n=1980) who underwent echocardiography between 1993 and 1995. Left ventricular ejection time was measured by pulsed-wave Doppler of the left ventricular outflow tract and related to outcomes. A shorter LVET was associated with younger age, male sex, higher diastolic blood pressure, higher proportion of diabetes, higher heart rate, higher blood glucose levels and worse fractional shortening. During a median follow-up of 17.6 years, 384 (19%) had incident heart failure (HF), 158 (8%) had a myocardial infarction, and 587 (30%) died. In univariable analysis, a lower LVET was significantly associated with increased risk of all events (P<0.05 for all). However, after multivariable adjustment for age, sex, hypertension, diabetes, body mass index, heart rate, systolic and diastolic blood pressure, fractional shortening and left atrial diameter, LVET remained an independent predictor only of incident HF [hazard ratio 1.07 (1.02-1.14), P=0.010 per 10 ms decrease]. In addition, LVET provided incremental prognostic information to the known risk factors included in the Framingham risk score, in regard to predicting all outcomes except for myocardial infarction. Left ventricular ejection time is an independent predictor of incident HF in a community-based cohort and provides incremental prognostic information on the risk of future HF and death when added to known risk prediction models. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

Medical malpractice claims in relation to colorectal malignancy in the national health service.

PubMed

Markides, G A; Newman, C M

2014-01-01

Under the current increased financial constraints affecting the National Health Service (NHS), clinical negligence claims and associated compensations are constantly rising. Our aim was to identify the magnitude, trends and causes of malpractice claims in relation to a common pathology such as colorectal malignancy in the NHS. Data requests were submitted to the NHS Litigation Authority (NHSLA) and to the Medical Defence Union (MDU) and Medical Protection Society (MPS). Data were reviewed, categorized clinically and analysed in terms of causes and costs behind claims. Data from the MPS and MDU were unavailable. In all, 169 claims were identified from the NHSLA database between 2003 and 2012; 123 (73%) cases had been closed, 80 (65%) of which were successful. An increasing overall claim frequency and success rate were found over the last few years. Total litigation expenses were £8.6 million, with 39% paid out as legal expenses. The commonest cause of complaint in successful claims was in relation to diagnostic delays or failures (58%, £5.1 million), with a delay or failure by the clinician to take action in response to an abnormal investigation result being a major factor. The occurrence of peri-operative complications (20%, £1.6 million) was the second commonest cause. Average frequency and success rates of malpractice claims in secondary care in the NHS are rising, leading to significant overall payouts. The failure or delay in diagnosing colorectal malignancy or its postoperative complications is a common cause behind malpractice claims. Improvement in these areas could enhance patient care and reduce future claims. Colorectal Disease © 2013 The Association of Coloproctology of Great Britain and Ireland.

Perioperative use of nonsteroidal anti-inflammatory drugs and the risk of anastomotic failure in emergency general surgery.

PubMed

Haddad, Nadeem N; Bruns, Brandon R; Enniss, Toby M; Turay, David; Sakran, Joseph V; Fathalizadeh, Alisan; Arnold, Kristen; Murry, Jason S; Carrick, Matthew M; Hernandez, Matthew C; Lauerman, Margaret H; Choudhry, Asad J; Morris, David S; Diaz, Jose J; Phelan, Herb A; Zielinski, Martin D

2017-10-01

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used analgesic and anti-inflammatory adjuncts. Nonsteroidal anti-inflammatory drug administration may potentially increase the risk of postoperative gastrointestinal anastomotic failure (AF). We aim to determine if perioperative NSAID utilization influences gastrointestinal AF in emergency general surgery (EGS) patients undergoing gastrointestinal resection and anastomosis. Post hoc analysis of a multi-institutional prospectively collected database was performed. Anastomotic failure was defined as the occurrence of a dehiscence/leak, fistula, or abscess. Patients using NSAIDs were compared with those without. Summary, univariate, and multivariable analyses were performed. Five hundred thirty-three patients met inclusion criteria with a mean (±SD) age of 60 ± 17.5 years, 53% men. Forty-six percent (n = 244) of the patients were using perioperative NSAIDs. Gastrointestinal AF rate between NSAID and no NSAID was 13.9% versus 10.7% (p = 0.26). No differences existed between groups with respect to perioperative steroid use (16.8% vs. 13.8%; p = 0.34) or mortality (7.39% vs. 6.92%, p = 0.84). Multivariable analysis demonstrated that perioperative corticosteroid (odds ratio, 2.28; 95% confidence interval, 1.04-4.81) use and the presence of a colocolonic or colorectal anastomoses were independently associated with AF. A subset analysis of the NSAIDs cohort demonstrated an increased AF rate in colocolonic or colorectal anastomosis compared with enteroenteric or enterocolonic anastomoses (30.0% vs. 13.0%; p = 0.03). Perioperative NSAID utilization appears to be safe in EGS patients undergoing small-bowel resection and anastomosis. Nonsteroidal anti-inflammatory drug administration should be used cautiously in EGS patients with colon or rectal anastomoses. Future randomized trials should validate the effects of perioperative NSAIDs use on AF. Therapeutic study, level III.

Failure-to-rescue after injury is associated with preventability: The results of mortality panel review of failure-to-rescue cases in trauma.

PubMed

Kuo, Lindsay E; Kaufman, Elinore; Hoffman, Rebecca L; Pascual, Jose L; Martin, Niels D; Kelz, Rachel R; Holena, Daniel N

2017-03-01

Failure-to-rescue is defined as the conditional probability of death after a complication, and the failure-to-rescue rate reflects a center's ability to successfully "rescue" patients after complications. The validity of the failure-to-rescue rate as a quality measure is dependent on the preventability of death and the appropriateness of this measure for use in the trauma population is untested. We sought to evaluate the relationship between preventability and failure-to-rescue in trauma. All adjudications from a mortality review panel at an academic level I trauma center from 2005-2015 were merged with registry data for the same time period. The preventability of each death was determined by panel consensus as part of peer review. Failure-to-rescue deaths were defined as those occurring after any registry-defined complication. Univariate and multivariate logistic regression models between failure-to-rescue status and preventability were constructed and time to death was examined using survival time analyses. Of 26,557 patients, 2,735 (10.5%) had a complication, of whom 359 died for a failure-to-rescue rate of 13.2%. Of failure-to-rescue deaths, 272 (75.6%) were judged to be non-preventable, 65 (18.1%) were judged potentially preventable, and 22 (6.1%) were judged to be preventable by peer review. After adjusting for other patient factors, there remained a strong association between failure-to-rescue status and potentially preventable (odds ratio 2.32, 95% confidence interval, 1.47-3.66) and preventable (odds ratio 14.84, 95% confidence interval, 3.30-66.71) judgment. Despite a strong association between failure-to-rescue status and preventability adjudication, only a minority of deaths meeting the definition of failure to rescue were judged to be preventable or potentially preventable. Revision of the failure-to-rescue metric before use in trauma care benchmarking is warranted. Copyright © 2016 Elsevier Inc. All rights reserved.

Failure-to-rescue after injury is associated with preventability: The results of mortality panel review of failure-to-rescue cases in trauma

PubMed Central

Kuo, Lindsay E.; Kaufman, Elinore; Hoffman, Rebecca L.; Pascual, Jose L.; Martin, Niels D.; Kelz, Rachel R.; Holena, Daniel N.

2018-01-01

Background Failure-to-rescue is defined as the conditional probability of death after a complication, and the failure-to-rescue rate reflects a center’s ability to successfully “rescue” patients after complications. The validity of the failure-to-rescue rate as a quality measure is dependent on the preventability of death and the appropriateness of this measure for use in the trauma population is untested. We sought to evaluate the relationship between preventability and failure-to-rescue in trauma. Methods All adjudications from a mortality review panel at an academic level I trauma center from 2005–2015 were merged with registry data for the same time period. The preventability of each death was determined by panel consensus as part of peer review. Failure-to-rescue deaths were defined as those occurring after any registry-defined complication. Univariate and multivariate logistic regression models between failure-to-rescue status and preventability were constructed and time to death was examined using survival time analyses. Results Of 26,557 patients, 2,735 (10.5%) had a complication, of whom 359 died for a failure-to-rescue rate of 13.2%. Of failure-to-rescue deaths, 272 (75.6%) were judged to be non-preventable, 65 (18.1%) were judged potentially preventable, and 22 (6.1%) were judged to be preventable by peer review. After adjusting for other patient factors, there remained a strong association between failure-to-rescue status and potentially preventable (odds ratio 2.32, 95% confidence interval, 1.47–3.66) and preventable (odds ratio 14.84, 95% confidence interval, 3.30–66.71) judgment. Conclusion Despite a strong association between failure-to-rescue status and preventability adjudication, only a minority of deaths meeting the definition of failure to rescue were judged to be preventable or potentially preventable. Revision of the failure-to-rescue metric before use in trauma care benchmarking is warranted. PMID:27788924

A more realistic disc herniation model incorporating compression, flexion and facet-constrained shear: a mechanical and microstructural analysis. Part II: high rate or 'surprise' loading.

PubMed

Shan, Zhi; Wade, Kelly R; Schollum, Meredith L; Robertson, Peter A; Thambyah, Ashvin; Broom, Neil D

2017-10-01

Part I of this study explored mechanisms of disc failure in a complex posture incorporating physiological amounts of flexion and shear at a loading rate considerably lower than likely to occur in a typical in vivo manual handling situation. Given the strain-rate-dependent mechanical properties of the heavily hydrated disc, loading rate will likely influence the mechanisms of disc failure. Part II investigates the mechanisms of failure in healthy discs subjected to surprise-rate compression while held in the same complex posture. 37 motion segments from 13 healthy mature ovine lumbar spines were compressed in a complex posture intended to simulate the situation arising when bending and twisting while lifting a heavy object at a displacement rate of 400 mm/min. Seven of the 37 samples reached the predetermined displacement prior to a reduction in load and were classified as early stage failures, providing insight to initial areas of disc disruption. Both groups of damaged discs were then analysed microstructurally using light microscopy. The average failure load under high rate complex loading was 6.96 kN (STD 1.48 kN), significantly lower statistically than for low rate complex loading [8.42 kN (STD 1.22 kN)]. Also, unlike simple flexion or low rate complex loading, direct radial ruptures and non-continuous mid-wall tearing in the posterior and posterolateral regions were commonly accompanied by disruption extending to the lateral and anterior disc. This study has again shown that multiple modes of damage are common when compressing a segment in a complex posture, and the load bearing ability, already less than in a neutral or flexed posture, is further compromised with high rate complex loading.

Postflight analysis of the single-axis acoustic system on SPAR VI and recommendations for future flights

NASA Technical Reports Server (NTRS)

Naumann, R. J.; Oran, W. A.; Whymark, R. R.; Rey, C.

1981-01-01

The single axis acoustic levitator that was flown on SPAR VI malfunctioned. The results of a series of tests, analyses, and investigation of hypotheses that were undertaken to determine the probable cause of failure are presented, together with recommendations for future flights of the apparatus. The most probable causes of the SPAR VI failure were lower than expected sound intensity due to mechanical degradation of the sound source, and an unexpected external force that caused the experiment sample to move radially and eventually be lost from the acoustic energy well.

Description of a flow optimized oxygenator with integrated pulsatile pump.

PubMed

Borchardt, Ralf; Schlanstein, Peter; Arens, Jutta; Graefe, Roland; Schreiber, Fabian; Schmitz-Rode, Thomas; Steinseifer, Ulrich

2010-11-01

Extracorporeal membrane oxygenation (ECMO) is a well-established therapy for several lung and heart diseases in the field of neonatal and pediatric medicine (e.g., acute respiratory distress syndrome, congenital heart failure, cardiomyopathy). Current ECMO systems are typically composed of an oxygenator and a separate nonpulsatile blood pump. An oxygenator with an integrated pulsatile blood pump for small infant ECMO was developed, and this novel concept was tested regarding functionality and gas exchange rate. Pulsating silicone tubes (STs) were driven by air pressure and placed inside the cylindrical fiber bundle of an oxygenator to be used as a pump module. The findings of this study confirm that pumping blood with STs is a viable option for the future. The maximum gas exchange rate for oxygen is 48mL/min/L(blood) at a medium blood flow rate of about 300mL/min. Future design steps were identified to optimize the flow field through the fiber bundle to achieve a higher gas exchange rate. First, the packing density of the hollow-fiber bundle was lower than commercial oxygenators due to the manual manufacturing. By increasing this packing density, the gas exchange rate would increase accordingly. Second, distribution plates for a more uniform blood flow can be placed at the inlet and outlet of the oxygenator. Third, the hollow-fiber membranes can be individually placed to ensure equal distances between the surrounding hollow fibers. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

The British antibiotic and silver-impregnated catheters for ventriculoperitoneal shunts multi-centre randomised controlled trial (the BASICS trial): study protocol

PubMed Central

2014-01-01

Background Insertion of a ventriculoperitoneal shunt (VPS) for the treatment of hydrocephalus is one of the most common neurosurgical procedures in the UK, but failures caused by infection occur in approximately 8% of primary cases. VPS infection is associated with considerable morbidity and mortality and its management results in substantial cost to the health service. Antibiotic-impregnated (rifampicin and clindamycin) and silver-impregnated VPS have been developed to reduce infection rates. Whilst there is some evidence showing that such devices may lead to a reduction in VPS infection, there are no randomised controlled trials (RCTs) to support their routine use. Methods/design Overall, 1,200 patients will be recruited from 17 regional neurosurgical units in the UK and Ireland. Patients of any age undergoing insertion of their first VPS are eligible. Patients with previous indwelling VPS, active and on-going cerebrospinal fluid (CSF) or peritoneal infection, multiloculated hydrocephalus requiring multiple VPS or neuroendoscopy, and ventriculoatrial or ventriculopleural shunt planned will be excluded. Patients will be randomised 1:1:1 to either standard silicone (comparator), antibiotic-impregnated, or silver-impregnated VPS. The primary outcome measure is time to VPS infection. Secondary outcome measures include time to VPS failure of any cause, reason for VPS failure (infection, mechanical failure, or patient failure), types of bacterial VPS infection (organism type and antibiotic resistance), and incremental cost per VPS failure averted. Discussion The British antibiotic and silver-impregnated catheters for ventriculoperitoneal shunts multi-centre randomised controlled trial (the BASICS trial) is the first multi-centre RCT designed to determine whether antibiotic or silver-impregnated VPS reduce early shunt infection compared to standard silicone VPS. The results of this study will be used to inform current neurosurgical practice and may potentially benefit patients undergoing shunt surgery in the future. Trial registration International Standard Randomised Controlled Trial Number: ISRCTN49474281. PMID:24383496

Modeling the roles of damage accumulation and mechanical healing on rainfall-induced landslides

NASA Astrophysics Data System (ADS)

Fan, Linfeng; Lehmann, Peter; Or, Dani

2014-05-01

The abrupt release of rainfall-induced shallow landslides is preceded by local failures that may abruptly coalesce and form a continuous failure plane within a hillslope. The mechanical status of hillslopes reflects a competition between the extent of severity of accumulated local damage during prior rainfall events and the rates of mechanically healing (i.e. regaining of strength) by closure of micro-cracks, regrowth of roots, etc. The interplay of these processes affects the initial conditions for landslide modeling and shapes potential failure patterns during future rainfall events. We incorporated these competing mechanical processes in a hydro-mechanical landslide triggering model subjected to a sequence of rainfall scenarios. The model employs the Fiber Bundle Model (FBM) with bonds (fiber bundle) with prescribed threshold linking adjacent soil columns and soil to bedrock. Prior damage was represented by a fraction of broken fibers during previous rainfall events, and the healing of broken fibers was described by strength regaining models for soil and roots at different characteristic time scales. Results show that prior damage and healing introduce highly nonlinear response to landslide triggering. For small prior damage, mechanical bonds at soil-bedrock interface may fail early in next rainfall event but lead to small perturbations onto lateral bonds without triggering a landslide. For more severe damage weakening lateral bonds, excess load due to failure at soil-bedrock interface accumulates at downslope soil columns resulting in early soil failure with patterns strongly correlated with prior damage distribution. Increasing prior damage over the hillslope decreases the volume of first landslide and prolongs the time needed to trigger the second landslide due to mechanical relaxation of the system. The mechanical healing of fibers diminishes effects of prior damage on the time of failure, and shortens waiting time between the first and second landslides. These findings highlight the need to improve definition of initial conditions and the shortcomings of assuming pristine hillslopes.

Investigating the health profile of patients with end-stage renal failure receiving peritoneal dialysis: a cluster analysis.

PubMed

Chan, M F; Wong, Frances K Y; Chow, Susan K Y

2010-03-01

To determine whether the patients with end stage renal failure can be differentiated into several subtypes based on five main variables. There is a lack of interventional research linking to clinical outcomes among the patients with end stage renal failure in Hong Kong and with no clear evidence of differences in terms of their clinical/health outcomes and characteristics. A cross-sectional survey. Data were collected using a structured questionnaire. One hundred and fifty-three patients with end stage renal failure were recruited during 2007 at three renal centres in Hong Kong. Five main variables were employed: predisposing characteristic, enabling resources, quality of life, symptom control and self-care adherence. A cluster analysis yielded two clusters. Each cluster represented a different profile of patients with end stage renal failure. Cluster A consisted of 49.7% (n = 76) and Cluster B consisted of 50.3% (n = 77) of the patients. Cluster A patients, more of whom were women, were older, less educated, had higher quality of life scores, a better adherence rate and more had received nursing care supports than patients in Cluster B. We have identified two groupings of patients with end stage renal failure who were experiencing unique health profile. Nursing support services may have an effect on patient health outcomes but only on a group of patients whose profile is similar to the patients in Cluster A and not for patients in Cluster B. A clear profile may help health care professional make appropriate strategies to target a specific group of patients to improve patient outcomes. The identification of risk for future health-care use could enable better targeting of interventional strategies in these groups. The results of this study might provide health care professionals with a model to design specified interventions to improve life quality for each profile group.

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 stochastic in nature because the mean failure energy and burst pressure values were not predictive of locus and morphology. Instead, flow rate and fibrin concentration showed the most predictive value, with the outcome best described as a probability distribution rather than a specific deterministic outcome.

How Often and Why MODIS Cloud Property Retrievals Fail for Liquid-Phase Clouds over Ocean? a Comprehensive Analysis Based on a-Train Observations

NASA Astrophysics Data System (ADS)

Zhang, Z.; Cho, H. M.; Platnick, S. E.; Meyer, K.; Lebsock, M. D.

2014-12-01

The cloud optical thickness (τ) and droplet effective radius (re) are two key cloud parameters retrieved by MODIS (Moderate Resolution Imaging Spectroradiometer). These MODIS cloud products are widely used in a broad range of earth system science applications. In this paper, we present a comprehensive analysis of the failed cloud τ and/or re retrievals for liquid-phase clouds over ocean in the Collection 6 MODIS cloud product. The main findings from this study are summarized as follows: MODIS retrieval failure rates for marine boundary layer (MBL) clouds have a strong dependence on the spectral combination used for retrieval (e.g., 0.86 + 2.1 µm vs. 0.8 + 3.7 µm) and the cloud morphology (i.e., "good" pixels vs. partly cloudy (PCL) pixels). Combining all clear-sky-restoral (CSR) categories (CSR=0,1 and 3), the 0.86 + 2.1 µm and 0.86 + 3.7 µm spectral combinations have an overall failure rate of about 20% and 12%, respectively (See figure below). The PCL pixels (CSR=1 & 3) have significantly higher failure rates and contribute more to the total failure population than the "good" (CSR=0) pixels. The majority of the failed retrievals are caused by the re too large failure, which explains about 85% and 70% of the failed 0.86 + 2.1 µm and 0.86 + 3.7 µm retrievals, respectively. The remaining failures are either due to the re too small failure or τ retrieval failure. The geographical distribution of failure rates has a significant dependence on cloud regime, lower over the coastal stratocumulus cloud regime and higher over the broken trade-wind cumulus cloud regime over open oceans. Enhanced retrieval failure rates are found when MBL clouds have high sub-pixel inhomogeneity , or are located at special Sun-satellite viewing geometries, such as sunglint, large viewing or solar zenith angle, or cloudbow and glory angles, or subject to cloud masking, cloud overlapping and/or cloud phase retrieval issues. About 80% of the failure retrievals can be attributed to at least one or more potential reasons mentioned above. Collocated radar reflectivity observations from CloudSat suggest that the remaining 20% are unlikely to be retrieval artifacts, but reflection of true cloud microphysics, i.e., the true is either truly very small or very large.

Prediction of failure pressure and leak rate of stress corrosion.

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

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

2002-06-24

An ''equivalent rectangular crack'' approach was employed to predict rupture pressures and leak rates through laboratory generated stress corrosion cracks and steam generator tubes removed from the McGuire Nuclear Station. Specimen flaws were sized by post-test fractography in addition to a pre-test advanced eddy current technique. The predicted and observed test data on rupture and leak rate are compared. In general, the test failure pressures and leak rates are closer to those predicted on the basis of fractography than on nondestructive evaluation (NDE). However, the predictions based on NDE results are encouraging, particularly because they have the potential to determinemore » a more detailed geometry of ligamented cracks, from which failure pressure and leak rate can be more accurately predicted. One test specimen displayed a time-dependent increase of leak rate under constant pressure.« less

Assuring reliability program effectiveness.

NASA Technical Reports Server (NTRS)

Ball, L. W.

1973-01-01

An attempt is made to provide simple identification and description of techniques that have proved to be most useful either in developing a new product or in improving reliability of an established product. The first reliability task is obtaining and organizing parts failure rate data. Other tasks are parts screening, tabulation of general failure rates, preventive maintenance, prediction of new product reliability, and statistical demonstration of achieved reliability. Five principal tasks for improving reliability involve the physics of failure research, derating of internal stresses, control of external stresses, functional redundancy, and failure effects control. A final task is the training and motivation of reliability specialist engineers.

Importance of teamwork, communication and culture on failure-to-rescue in the elderly.

PubMed

Ghaferi, A A; Dimick, J B

2016-01-01

Surgical mortality increases significantly with age. Wide variations in mortality rates across hospitals suggest potential levers for improvement. Failure-to-rescue has been posited as a potential mechanism underlying these differences. A review was undertaken of the literature evaluating surgery, mortality, failure-to-rescue and the elderly. This was followed by a review of ongoing studies and unpublished work aiming to understand better the mechanisms underlying variations in surgical mortality in elderly patients. Multiple hospital macro-system factors, such as nurse staffing, available hospital technology and teaching status, are associated with differences in failure-to-rescue rates. There is emerging literature regarding important micro-system factors associated with failure-to-rescue. These are grouped into three broad categories: hospital resources, attitudes and behaviours. Ongoing work to produce interventions to reduce variations in failure-to-rescue rates include a focus on teamwork, communication and safety culture. Researchers are using novel mixed-methods approaches and theories adapted from organizational studies in high-reliability organizations in an effort to improve the care of elderly surgical patients. Although elderly surgical patients experience failure-to-rescue events at much higher rates than their younger counterparts, patient-level effects do not sufficiently explain these differences. Increased attention to the role of organizational dynamics in hospitals' ability to rescue these high-risk patients will establish high-yield interventions aimed at improving patient safety. © 2015 BJS Society Ltd Published by John Wiley & Sons Ltd.

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.

Neutron-induced single event burnout in high voltage electronics

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

Normand, E.; Wert, J.L.; Oberg, D.L.

Energetic neutrons with an atmospheric neutron spectrum, which were demonstrated to induce single event burnout in power MOSFETs, have been shown to induce burnout in high voltage (>3,000V) electronics when operated at voltages as low as 50% of rated voltage. The laboratory failure rates correlate well with field failure rates measured in Europe.

Failure Analysis Handbook

DTIC Science & Technology

1989-08-18

conditions, strain rate , geometry, manufacturing variables, microstructure, surface conditions, and alloy contamination. Exzvples of service failures are...depends on the ductility of the material, strain rate and stress concentration. The macrosocpic appearances of two ductile overstress fractures are shown...distribution of nucleation sites, stress orientation, temperature, ductility and strain rate . The size of the dimples is oontrolled by the size, number ard

Azithromycin treatment failure for Chlamydia trachomatis among heterosexual men with nongonococcal urethritis

PubMed Central

Kissinger, Patricia; White, Scott; Manhart, Lisa E.; Schwebke, Jane; Taylor, Stephanie N; Mena, Leandro; Khosropour, Christine M; Wilcox, Larissa; Schmidt, Norine; Martin, David H

2016-01-01

Background Three recent prospective studies have suggested that the 1 g dose of azithromycin for Chlamydia trachomatis (Ct) was less effective than expected, reporting a wide range of treatment failure rates (5.8%–22.6%). Reasons for the disparate results could be attributed to geographic or methodological differences. The purpose of this study was to re-examine the studies and attempt to harmonize methodologies to reduce misclassification as a result of false positives from early test-of-cure (TOC) or reinfection as a result of sexual exposure rather than treatment failure. Methods Men who had sex with women, who received 1 g azithromycin under directly observed therapy (DOT) for presumptive treatment of nongonococcal urethritis (NGU) with confirmed Ct were included. Baseline screening was performed on urethral swabs or urine and TOC screening was performed on urine using nucleic acid amplification tests (NAAT). Post-treatment vaginal sexual exposure was elicited at TOC. Data from the three studies was obtained and re-analyzed. Rates of Ct re-test positive were examined for all cases and a sensitivity analysis was conducted to either reclassify potential false positives/reinfections as negative or remove them from the analysis. Results The crude treatment failure rate was 12.8% (31/242). The rate when potential false positives/reinfections were reclassified as negative was 6.2% (15/242) or when these were excluded from analysis was 10.9% (15/138). Conclusion In these samples of men who have sex with women with Ct-related NGU, azithromycin treatment failure was between 6.2% and 12.8%. This range of failure is lower than previously published but higher than the desired World Health Organization’s target chlamydia treatment failure rate of < 5%. PMID:27631353

Azithromycin Treatment Failure for Chlamydia trachomatis Among Heterosexual Men With Nongonococcal Urethritis.

PubMed

Kissinger, Patricia J; White, Scott; Manhart, Lisa E; Schwebke, Jane; Taylor, Stephanie N; Mena, Leandro; Khosropour, Christine M; Wilcox, Larissa; Schmidt, Norine; Martin, David H

2016-10-01

Three recent prospective studies have suggested that the 1-g dose of azithromycin for Chlamydia trachomatis (Ct) was less effective than expected, reporting a wide range of treatment failure rates (5.8%-22.6%). Reasons for the disparate results could be attributed to geographic or methodological differences. The purpose of this study was to reexamine the studies and attempt to harmonize methodologies to reduce misclassification as a result of false positives from early test-of-cure (TOC) or reinfection as a result of sexual exposure rather than treatment failure. Men who had sex with women, who received 1-g azithromycin under directly observed therapy for presumptive treatment of nongonococcal urethritis with confirmed Ct were included. Baseline screening was performed on urethral swabs or urine, and TOC screening was performed on urine using nucleic acid amplification tests. Posttreatment vaginal sexual exposure was elicited at TOC. Data from the 3 studies were obtained and reanalyzed. Rates of Ct retest positive were examined for all cases, and a sensitivity analysis was conducted to either reclassify potential false positives/reinfections as negative or remove them from the analysis. The crude treatment failure rate was 12.8% (31/242). The rate when potential false positives/reinfections were reclassified as negative was 6.2% (15/242) or when these were excluded from analysis was 10.9% (15/138). In these samples of men who have sex with women with Ct-related nongonococcal urethritis, azithromycin treatment failure was between 6.2% and 12.8%. This range of failure is lower than previously published but higher than the desired World Health Organization's target chlamydia treatment failure rate of < 5%.

The high failure rate of biologic resurfacing of the glenoid in young patients with glenohumeral arthritis.

PubMed

Strauss, Eric J; Verma, Nikhil N; Salata, Michael J; McGill, Kevin C; Klifto, Christopher; Nicholson, Gregory P; Cole, Brian J; Romeo, Anthony A

2014-03-01

The current study evaluated the outcomes of biologic resurfacing of the glenoid using a lateral meniscus allograft or human acellular dermal tissue matrix at intermediate-term follow-up. Forty-five patients (mean age, 42.2 years) underwent biologic resurfacing of the glenoid, and 41 were available for follow-up at a mean of 2.8 years. Lateral meniscal allograft resurfacing was used in 31 patients and human acellular dermal tissue matrix interposition in 10. Postoperative range of motion and clinical outcomes were assessed at the final follow-up. The overall clinical failure rate was 51.2%. The lateral meniscal allograft cohort had a failure rate of 45.2%, with a mean time to failure of 3.4 years. Human acellular dermal tissue matrix interposition had a failure rate of 70.0%, with a mean time to failure of 2.2 years. Overall, significant improvements were seen compared with baseline with respect to the visual analog pain score (3.0 vs. 6.3), American Shoulder and Elbow Surgeons score (62.0 vs. 36.8), and Simple Shoulder Test score (7.0 vs. 4.0). Significant improvements were seen for forward elevation (106° to 138°) and external rotation (31° to 51°). Despite significant improvements compared with baseline values, biologic resurfacing of the glenoid resulted in a high rate of clinical failure at intermediate follow-up. Our results suggest that biologic resurfacing of the glenoid may have a minimal and as yet undefined role in the management of glenohumeral arthritis in the young active patient over more traditional methods of hemiarthroplasty or total shoulder arthroplasty. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

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

PubMed

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

2012-10-01

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

The iothalamate clearance in cats with experimentally induced renal failure.

PubMed

Ohashi, F; Kuroda, K; Shimada, T; Shimada, Y; Ota, M

1996-08-01

Plasma iothalamate (IOT) disappearance rates were measured after a single-injection of IOT (113.8 mg/kg, IV) in cats with experimentally induced renal failure. The disappearance rates especially fitted into the one compartment model. The mean value of plasma disappearance rates of IOT in these cats with induced renal failure (2.16 +/- 0.240 x 10(-3) micrograms/ml/min) was markedly lower than that of clinically healthy cats (4.10 +/- 1.00 x 10(-3) micrograms/ml/min). These results demonstrate that IOT clearance is available for evaluation of renal function in cats.

A heart failure initiative to reduce the length of stay and readmission rates.

PubMed

White, Sabrina Marie; Hill, Alethea

2014-01-01

The purpose of this pilot was to improve multidisciplinary coordination of care and patient education and foster self-management behaviors. The primary and secondary outcomes achieved from this pilot were to decrease the 30-day readmission rate and heart failure length of stay. The primary practice site was an inpatient medical-surgical nursing unit. The length of stay decreased from 6.05% to 4.42% for heart failure diagnostic-related group 291 as a result of utilizing the model. The length of stay decreased from 3.9% to 3.09%, which was also less than the national rate of 3.8036% for diagnostic-related group 292. In addition, the readmission rate decreased from 23.1% prior to January 2013 to 12.9%. Implementation of standards of care coordination can decrease length of stay, readmission rate, and improve self-management. Implementation of evidence-based heart failure guidelines, improved interdisciplinary coordination of care, patient education, self-management skills, and transitional care at the time of discharge improved overall heart failure outcome measures. Utilizing the longitudinal model of care to transition patients to home aided in evaluating social support, resource allocation and utilization, access to care postdischarge, and interdisciplinary coordination of care. The collaboration between disciplines improved continuity of care, patient compliance to their discharge regimen, and adequate discharge follow-up.

A dual-center review of compressive osseointegration for fixation of massive endoprosthetics: 2- to 9-year followup.

PubMed

Calvert, George T; Cummings, Judd E; Bowles, Austin J; Jones, Kevin B; Wurtz, L Daniel; Randall, R Lor

2014-03-01

Aseptic failure of massive endoprostheses used in the reconstruction of major skeletal defects remains a major clinical problem. Fixation using compressive osseointegration was developed as an alternative to cemented and traditional press-fit fixation in an effort to decrease aseptic failure rates. The purpose of this study was to answer the following questions: (1) What is the survivorship of this technique at minimum 2-year followup? (2) Were patient demographic variables (age, sex) or anatomic location associated with implant failure? (3) Were there any prosthesis-related variables (eg, spindle size) associated with failure? (4) Was there a discernible learning curve associated with the use of the new device as defined by a difference in failure rate early in the series versus later on? The first 50 cases using compressive osseointegration fixation from two tertiary referral centers were retrospectively studied. Rates of component removal for any reason and for aseptic failure were calculated. Demographic, surgical, and oncologic factors were analyzed using regression analysis to assess for association with implant failure. Minimum followup was 2 years with a mean of 66 months. Median age at the time of surgery was 14.5 years. A total of 15 (30%) implants were removed for any reason. Of these revisions, seven (14%) were the result of aseptic failure. Five of the seven aseptic failures occurred at less than 1 year (average, 8.3 months), and none occurred beyond 17 months. With the limited numbers available, no demographic, surgical, or prosthesis-related factors correlated with failure. Most aseptic failures of compressive osseointegration occurred early. Longer followup is needed to determine if this technique is superior to other forms of fixation.

Care management for low-risk patients with heart failure: a randomized, controlled trial.

PubMed

DeBusk, Robert Frank; Miller, Nancy Houston; Parker, Kathleen Marie; Bandura, Albert; Kraemer, Helena Chmura; Cher, Daniel Joseph; West, Jeffrey Alan; Fowler, Michael Bruce; Greenwald, George

2004-10-19

Nurse care management programs for patients with chronic illness have been shown to be safe and effective. To determine whether a telephone-mediated nurse care management program for heart failure reduced the rate of rehospitalization for heart failure and for all causes over a 1-year period. Randomized, controlled trial of usual care with nurse management versus usual care alone in patients hospitalized for heart failure from May 1998 through October 2001. 5 northern California hospitals in a large health maintenance organization. Of 2786 patients screened, 462 met clinical criteria for heart failure and were randomly assigned (228 to intervention and 234 to usual care). Nurse care management provided structured telephone surveillance and treatment for heart failure and coordination of patients' care with primary care physicians. Time to first rehospitalization for heart failure or for any cause and time to a combined end point of first rehospitalization, emergency department visit, or death. At 1 year, half of the patients had been rehospitalized at least once and 11% had died. Only one third of rehospitalizations were for heart failure. The rate of first rehospitalization for heart failure was similar in both groups (proportional hazard, 0.85 [95% CI, 0.46 to 1.57]). The rate of all-cause rehospitalization was similar (proportional hazard, 0.98 [CI, 0.76 to 1.27]). The findings of this study, conducted in a single health care system, may not be generalizable to other health care systems. The overall effect of the intervention was minor. Among patients with heart failure at low risk on the basis of sociodemographic and medical attributes, nurse care management did not statistically significantly reduce rehospitalizations for heart failure or for any cause. Such programs may be less effective for patients at low risk than those at high risk.

Association of hospice utilization and publicly reported outcomes following hospitalization for pneumonia or heart failure: a retrospective cohort study.

PubMed

Lah, Soowhan; Wilson, Emily L; Beesley, Sarah; Sagy, Iftach; Orme, James; Novack, Victor; Brown, Samuel M

2018-01-09

The Center for Medicare and Medicaid Services (CMS) and the Hospital Quality Alliance began collecting and reporting United States hospital performance in the treatment of pneumonia and heart failure in 2008. Whether the utilization of hospice might affect CMS-reported mortality and readmission rates is not known. Hospice utilization (mean days on hospice per decedent) for 2012 from the Dartmouth Atlas (a project of the Dartmouth Institute that reports a variety of public health and policy-related statistics) was merged with hospital-level 30-day mortality and readmission rates for pneumonia and heart failure from CMS. The association between hospice use and outcomes was analyzed with multivariate quantile regression controlling for quality of care metrics, acute care bed availability, regional variability and other measures. 2196 hospitals reported data to both CMS and the Dartmouth Atlas in 2012. Higher rates of hospice utilization were associated with lower rates of 30-day mortality and readmission for pneumonia but not for heart failure. Higher quality of care was associated with lower rates of mortality for both pneumonia and heart failure. Greater acute care bed availability was associated with increased readmission rates for both conditions (p < 0.05 for all). Higher rates of hospice utilization were associated with lower rates of 30-day mortality and readmission for pneumonia as reported by CMS. While causality is not established, it is possible that hospice referrals might directly affect CMS outcome metrics. Further clarification of the relationship between hospice referral patterns and publicly reported CMS outcomes appears warranted.

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.

Study of the Progressive Failure of Composites under Axial Loading with Varying Strain Rates

DTIC Science & Technology

2011-12-01

8 a. Waddoups, Eisenmann , and Kaminski Failure Theory ..........8 b. Whitney-Nuismer Failure Theory ..........................................11...Width (m) WEK Waddoups, Eisenmann , and Kaminski failure theory xiv x Coordinate measured from center of notch perpendicular to direction of...comprised of differing assumptions, effort, and knowledge of material properties. a. Waddoups, Eisenmann , and Kaminski Failure Theory One of the

Contraceptive prevalence, reproductive health and our common future. The C. Donald Christian Memorial Lecture.

PubMed

Diczfalusy, E

1993-05-01

Worldwide, female sterilization is the most common contraceptive method, followed by IUDs and oral contraceptives. As unwanted pregnancy for women in developing countries can mean life or death, which may explain why modern contraceptive methods with low failure rates (e.g., sterilization, IUDs. and hormonal methods) predominate in developing countries. Conventional methods with relatively high failure rates (e.g., natural family planning, barrier methods, and withdrawal) predominate in developed countries. Developing-country governments first supported family planning programs for demographic reasons. They now embrace them because they save the lives of women and children. The four fundamental pillars of reproductive health policy are family planning, maternal care, infant and child care, and control of sexually transmitted diseases (STDs). Indicators of reproductive health include, rates of maternal mortality and morbidity; induced abortion; infertility; perinatal, infant, and child mortality; and STDs (including AIDS). Governments in the poorest countries invest only US$5 per capita for health, compared to US$400 per capita for developed countries. If the poorest countries increased that $5 figure by just $2 per capita, they could immunize all children, eradicate polio, and provide the drugs to cure the most common diseases. Further, if humans were to use resources more reasonably, we could greatly decrease the number of people living in poverty. Three UN population projections show that the population will continue to grow well within the next century. With strong commitment from governments and individuals, we can increase contraceptive use and reduce total fertility rates. Barriers to achieving those goals are few funds allocated to family planning methods and services; politicians; religious and community leaders; culture; low women's status; limited accessibility to information, methods, and quality services; and limited contraceptive choice.

Why Secondary Teachers Fail Students.

ERIC Educational Resources Information Center

Ligon, Glynn; Jackson, Elaine E.

The perceptions of teachers about students' lack of success were studied, and the groundwork was laid for the future study of the effectiveness of a policy of warning students and parents of impending failure. The primary sources of data were teacher-coded reasons for failure, given on notices (progress reports) to secondary school students in the…

[In vitro fertilization at the Erasme Hospital: 10 years and 1000 pregnancies later...].

PubMed

Englert, Y; Van den Bergh, M; Delbaere, A; Devreker, F; Koenig, I; Hannes, M; Emiliani, S; Biramane, J; Vannin, A S; Govaerts, I; Holoye, A; Revelard, P

1999-10-01

This contribution summarize ten years of in vitro fertilization of clinical work. Activity growth, improvements of results (mean fertilization rate increased from 45% to 58%, fertilization failure dropped from 18% to 7%, pregnancy chances gains 9% to reach 44% per trial) and new treatments possibilities (severe male infertility) thanks to the ICSI technic were the major characteristics of this last ten years. The original anonymous oocyte donation program with donors permutation initiated as soon as 1990 has imposed itself due to it's exceptional efficiency with a pregnancy rate of 95% per oocyte pick up on a population of 46 donors and 145 recipient cycles. Thanks to the large population studied (4028 cycles, 1071 pregnancies), the tendencies in human fecundity (impact of age) and the risks linked to multiples pregnancies could be highlighted, stressing the importance of future developments presented in the other contributions following this general presentation of results.

Arctic megaslide at presumed rest

PubMed Central

Geissler, Wolfram H.; Gebhardt, A. Catalina; Gross, Felix; Wollenburg, Jutta; Jensen, Laura; Schmidt-Aursch, Mechita C.; Krastel, Sebastian; Elger, Judith; Osti, Giacomo

2016-01-01

Slope failure like in the Hinlopen/Yermak Megaslide is one of the major geohazards in a changing Arctic environment. We analysed hydroacoustic and 2D high-resolution seismic data from the apparently intact continental slope immediately north of the Hinlopen/Yermak Megaslide for signs of past and future instabilities. Our new bathymetry and seismic data show clear evidence for incipient slope instability. Minor slide deposits and an internally-deformed sedimentary layer near the base of the gas hydrate stability zone imply an incomplete failure event, most probably about 30000 years ago, contemporaneous to or shortly after the Hinlopen/Yermak Megaslide. An active gas reservoir at the base of the gas hydrate stability zone demonstrate that over-pressured fluids might have played a key role in the initiation of slope failure at the studied slope, but more importantly also for the giant HYM slope failure. To date, it is not clear, if the studied slope is fully preconditioned to fail completely in future or if it might be slowly deforming and creeping at present. We detected widespread methane seepage on the adjacent shallow shelf areas not sealed by gas hydrates. PMID:27922097

Arctic megaslide at presumed rest

NASA Astrophysics Data System (ADS)

Geissler, Wolfram H.; Gebhardt, A. Catalina; Gross, Felix; Wollenburg, Jutta; Jensen, Laura; Schmidt-Aursch, Mechita C.; Krastel, Sebastian; Elger, Judith; Osti, Giacomo

2016-12-01

Slope failure like in the Hinlopen/Yermak Megaslide is one of the major geohazards in a changing Arctic environment. We analysed hydroacoustic and 2D high-resolution seismic data from the apparently intact continental slope immediately north of the Hinlopen/Yermak Megaslide for signs of past and future instabilities. Our new bathymetry and seismic data show clear evidence for incipient slope instability. Minor slide deposits and an internally-deformed sedimentary layer near the base of the gas hydrate stability zone imply an incomplete failure event, most probably about 30000 years ago, contemporaneous to or shortly after the Hinlopen/Yermak Megaslide. An active gas reservoir at the base of the gas hydrate stability zone demonstrate that over-pressured fluids might have played a key role in the initiation of slope failure at the studied slope, but more importantly also for the giant HYM slope failure. To date, it is not clear, if the studied slope is fully preconditioned to fail completely in future or if it might be slowly deforming and creeping at present. We detected widespread methane seepage on the adjacent shallow shelf areas not sealed by gas hydrates.

The big bang of hemofiltration: the beginning of a new era in the third millennium for extra-corporeal blood purification!

PubMed

Honore', P M; Joannes-Boyau, O; Merson, L; Boer, W; Piette, V; Galloy, A-C; Janvier, G

2006-07-01

Since the last decade, hemofiltration and especially high volume hemofiltration has rapidly evolved from a somewhat experimental treatment towards a potentially effective 'adjunctive' therapy in severe septic shock and especially refractory or catecholamine resistant hypodynamic septic shock. Nevertheless, this approach lacks prospective randomized studies (PRT'S) evaluating the critical role of early hemofiltration in sepsis. An important step forward which could be called the 'big bang' in term of hemofiltration was the publication of a PRT in patients with acute renal failure (ARF) (1). Before this study (2), nobody believed that hemofiltration could change the survival rate in intensive care. Since that big bang, many physicians consider that hemofiltration at a certain dose can change the survival rate in intensive care. So the world of hemofiltration in ICU is not a definitive world, it is still in expansion. Indeed, we now have to try to define what will be the exact dose we need in septic acute renal failure. This dose might well be 'higher' than 35 ml/kg/hour in the septic acute renal failure 'group' as suggested by many studies (2-5). At present, it is the issue of continuous dose of high volume hemofiltration that has to be tested in future randomized studies. Since the Vicenza study (2) has shown that 35 ml/kg/h is the best dose in terms of survival, dealing with non septic acute renal failure in ICU, several studies from different groups have shown that, in septic acute renal failure, a higher dose might correlate with better survival. This has also been shown in some way by the study of the 'Vicenza group' but not with a statistically significant value (2). New PRT'S have just started in Europe like the IVOIRE study (hIgh VOlume in Intensive caRE) (6) and the RENAL study. Another large study is looking more basically at dose in non septic acute renal failure in Australasia and is led by the group of Rinaldo Bellomo in Melbourne (7) as well as the ATN study (8) led by Palevsky and colleagues in the USA, also testing the importance of dose in the treatment for ARF. Nevertheless, 'early goal-directed hemofiltration therapy' like early goal directed therapy (9) has to be studied in our critical ill patients. Regarding this issue, fewer studies, mainly retrospective exist, but again the IVOIRE study (6) will address this issue by studying septic patients with acute renal injury according to the Rifle classification (10). So, this review focuses on the early application and on the adequate dose of continuous high volume hemofiltration in septic shock in order to improve not only hemodynamics, but survival in this very severely ill cohort of patients. This could well be called the 'big bang of hemofiltration' as one could never have anticipated that an adequate dose of hemofiltration could markedly influence the survival rate of ICU-septic acute renal failure patients. On top of the use of early and adequate dose of hemofiltration in sepsis, a higher dose could also provide better renal recovery rate and reduce the risk of associate chronic dialysis in these patients. Furthermore, this paper also reviews 'brand' new theories regarding the rationale for hemofiltration in sepsis. Finally, this paper also addresses the so-called negative studies as well anticipated side effects.

Anatomy of a bottleneck: diagnosing factors limiting population growth in the Puerto Rican parrot

USGS Publications Warehouse

Beissenger, S.R.; Wunderle, J.M.; Meyers, J.M.; Saether, B.-E.; Engen, S.

2008-01-01

The relative importance of genetic, demographic, environmental, and catastrophic processes that maintain population bottlenecks has received little consideration. We evaluate the role of these factors in maintaining the Puerto Rican Parrot (Amazona vittata) in a prolonged bottleneck from 1973 through 2000 despite intensive conservation efforts. We first conduct a risk analysis, then examine evidence for the importance of specific processes maintaining the bottleneck using the multiple competing hypotheses approach, and finally integrate these results through a sensitivity analysis of a demographic model using life-stage simulation analysis (LSA) to determine the relative importance of genetic, demographic, environmental, and catastrophic processes on population growth. Annual population growth has been slow and variable (1.0 6 5.2 parrots per year, or an average k?1.05 6 0.19) from 16 parrots (1973) to a high of 40-42 birds (1997-1998). A risk analysis based on population prediction intervals (PPI) indicates great risk and large uncertainty, with a range of 22?83 birds in the 90% PPI only five years into the future. Four primary factors (reduced hatching success due to inbreeding, failure of adults to nest, nest failure due to nongenetic causes, and reduced survival of adults and juveniles) were responsible for maintaining the bottleneck. Egghatchability rates were low (70.6% per egg and 76.8% per pair), and hatchability increased after mate changes, suggesting inbreeding effects. Only an average of 34% of the population nested annually, which was well below the percentage of adults that should have reached an age of first breeding (41-56%). This chronic failure to nest appears to have been caused primarily by environmental and/or behavioral factors, and not by nest-site scarcity or a skewed sex ratio. Nest failure rates from nongenetic causes (i.e., predation, parasitism, and wet cavities) were low (29%) due to active management (protecting nests and fostering captive young into wild nests), diminishing the importance of nest failure as a limiting factor. Annual survival has been periodically reduced by catastrophes (hurricanes), which have greatly constrained population growth, but survival rates were high under non-catastrophic conditions. Although the importance of factors maintaining the Puerto Rican Parrot bottleneck varied throughout the 30-year period of study, we determined their long-term influence using LSA simulations to correlate variation in demographic rates with variation in population growth (k). The bottleneck appears to have been maintained primarily by periodic catastrophes (hurricanes) that reduced adult survival, and secondarily by environmental and/or behavioral factors that resulted in a failure of many adults to nest. The influence of inbreeding through reduced hatching success played a much less significant role, even when additional effects of inbreeding on the production and mortality of young were incorporated into the LSA. Management actions needed to speed recovery include (1) continued nest guarding to minimize the effects of nest failure due to nongenetic causes; (2) creating a second population at another location on the island --a process that was recently initiated--to reduce the chance that hurricane strikes will cause extinction; and (3) determining the causes of the low percentage of breeders in the population and ameliorating them, which would have a large impact on population growth.

New findings confirm the viscoelastic behaviour of the inter-lamellar matrix of the disc annulus fibrosus in radial and circumferential directions of loading.

PubMed

Tavakoli, J; Costi, J J

2018-04-15

While few studies have improved our understanding of composition and organization of elastic fibres in the inter-lamellar matrix (ILM), its clinical relevance is not fully understood. Moreover, no studies have measured the direct tensile and shear failure and viscoelastic properties of the ILM. Therefore, the aim of this study was, for the first time, to measure the viscoelastic and failure properties of the ILM in both the tension and shear directions of loading. Using an ovine model, isolated ILM samples were stretched to 40% of their initial length at three strain rates of 0.1%s -1 (slow), 1%s -1 (medium) and 10%s -1 (fast) and a ramp test to failure was performed at a strain rate of 10%s -1 . The findings from this study identified that the stiffness of the ILM was significantly larger at faster strain rates, and energy absorption significantly smaller, compared to slower strain rates, and the viscoelastic and failure properties were not significantly different under tension and shear loading. We found a strain rate dependent response of the ILM during dynamic loading, particularly at the fastest rate. The ILM demonstrated a significantly higher capability for energy absorption at slow strain rates compared to medium and fast strain rates. A significant increase in modulus was found in both loading directions and all strain rates, having a trend of larger modulus in tension and at faster strain rates. The finding of no significant difference in failure properties in both loading directions, was consistent with our previous ultra-structural studies that revealed a well-organized (±45°) elastic fibre orientation in the ILM. The results from this study can be used to develop and validate finite element models of the AF at the tissue scale, as well as providing new strategies for fabricating tissue engineered scaffolds. While few studies have improved our understanding of composition and organization of elastic fibres in the inter-lamellar matrix (ILM) of the annulus in the disc no studies have measured the direct mechanical failure and viscoelastic properties of the ILM. The findings from this study identified that the stiffness of the ILM was significantly larger at faster strain rates, and energy absorption significantly smaller, compared to slower strain rates. The failure properties of the ILM were not significantly different under tension and shear. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

[Atrial fibrillation as a comorbidity of heart failure].

PubMed

Wachter, R

2018-05-01

Atrial fibrillation and heart failure are diseases that frequently occur together in patients, and the prevalence of the two diseases will continue to increase in the future. Unfortunately, they exacerbate each other: the prognosis of patients with atrial fibrillation is poorer if there is heart failure, and the prognosis of heart failure patients with atrial fibrillation is poorer than the prognosis of heart failure patients without atrial fibrillation. In the past, studies on drug stabilization of sinus rhythm with antiarrhythmic drugs were not able to show any influence on the prognosis of patients. In these patients, it seems to be better to treat the atrial fibrillation interventionally. The CASTLE-AF study has just shown for the first time that isolation of the pulmonary vein to treat atrial fibrillation in heart failure patients has positive effects: hospital admissions for heart failure decreased and the overall survival improved. Further studies have shown that quality of life improves and performance is increased.

The Relationship Between Heart Rate Reserve and Oxygen Uptake Reserve in Heart Failure Patients on Optimized and Non-Optimized Beta-Blocker Therapy

PubMed Central

Carvalho, Vitor Oliveira; Guimarães, Guilherme Veiga; Bocchi, Edimar Alcides

2008-01-01

BACKGROUND The relationship between the percentage of oxygen consumption reserve and percentage of heart rate reserve in heart failure patients either on non-optimized or off beta-blocker therapy is known to be unreliable. The aim of this study was to evaluate the relationship between the percentage of oxygen consumption reserve and percentage of heart rate reserve in heart failure patients receiving optimized and non-optimized beta-blocker treatment during a treadmill cardiopulmonary exercise test. METHODS A total of 27 sedentary heart failure patients (86% male, 50±12 years) on optimized beta-blocker therapy with a left ventricle ejection fraction of 33±8% and 35 sedentary non-optimized heart failure patients (75% male, 47±10 years) with a left ventricle ejection fraction of 30±10% underwent the treadmill cardiopulmonary exercise test (Naughton protocol). Resting and peak effort values of both the percentage of oxygen consumption reserve and percentage of heart rate reserve were, by definition, 0 and 100, respectively. RESULTS The heart rate slope for the non-optimized group was derived from the points 0.949±0.088 (0 intercept) and 1.055±0.128 (1 intercept), p<0.0001. The heart rate slope for the optimized group was derived from the points 1.026±0.108 (0 intercept) and 1.012±0.108 (1 intercept), p=0.47. Regression linear plots for the heart rate slope for each patient in the non-optimized and optimized groups revealed a slope of 0.986 (almost perfect) for the optimized group, but the regression analysis for the non-optimized group was 0.030 (far from perfect, which occurs at 1). CONCLUSION The relationship between the percentage of oxygen consumption reserve and percentage of heart rate reserve in patients on optimized beta-blocker therapy was reliable, but this relationship was unreliable in non-optimized heart failure patients. PMID:19060991

Probabilistic reanalysis of twentieth-century sea-level rise.

PubMed

Hay, Carling C; Morrow, Eric; Kopp, Robert E; Mitrovica, Jerry X

2015-01-22

Estimating and accounting for twentieth-century global mean sea level (GMSL) rise is critical to characterizing current and future human-induced sea-level change. Several previous analyses of tide gauge records--employing different methods to accommodate the spatial sparsity and temporal incompleteness of the data and to constrain the geometry of long-term sea-level change--have concluded that GMSL rose over the twentieth century at a mean rate of 1.6 to 1.9 millimetres per year. Efforts to account for this rate by summing estimates of individual contributions from glacier and ice-sheet mass loss, ocean thermal expansion, and changes in land water storage fall significantly short in the period before 1990. The failure to close the budget of GMSL during this period has led to suggestions that several contributions may have been systematically underestimated. However, the extent to which the limitations of tide gauge analyses have affected estimates of the GMSL rate of change is unclear. Here we revisit estimates of twentieth-century GMSL rise using probabilistic techniques and find a rate of GMSL rise from 1901 to 1990 of 1.2 ± 0.2 millimetres per year (90% confidence interval). Based on individual contributions tabulated in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, this estimate closes the twentieth-century sea-level budget. Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records.The increase in rate relative to the 1901-90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-level rise.

Liver Function Assessment Using Technetium 99m-Galactosyl Single-Photon Emission Computed Tomography/CT Fusion Imaging: A Prospective Trial.

PubMed

Okabayashi, Takehiro; Shima, Yasuo; Morita, Sojiro; Shimada, Yasuhiro; Sumiyoshi, Tatsuaki; Sui, Kenta; Iwata, Jun; Iiyama, Tatsuo

2017-12-01

The prediction of postoperative liver function remains a largely subjective practice based on CT volumetric analysis. However, future liver volume after a hepatectomy is not the only factor that contributes to postoperative liver function and outcomes. In this prospective trial, 185 consecutive patients who underwent liver operations between 2014 and 2015 were studied. Volumetric and functional rates of remnant liver were measured using technetium 99m-galactosyl human serum albumin single-photon emission computed tomography/CT fusion imaging to evaluate post-hepatectomy remnant liver function. Remnant indocyanine green clearance rate using galactosyl (KGSA) (KGSA × functional rate) was used to predict future remnant liver function. Hepatectomy was considered safe for patients with remnant KGSA values ≥0.05, and the primary end point was to determine the accuracy and reliability of this criteria. The prediction of the 90-day major complication and mortality rates was assessed. Median hospital stay was 9 days and median ICU stay was 1 day, with only 1 in-hospital death (90-day mortality rate 0.5%). Overall morbidity rate evaluated according to the Clavien-Dindo classification was 9%. For post-hepatectomy liver failure definitions, the International Study Group of Liver Surgery definition was fulfilled in 14 patients (8%), with the majority being grade B (50%), compared with 2 patients (1%) fulfilling the "50-50" criteria, and 0 patients (0%) fulfilling the Peak Bili >7 criteria. Results of this study showed that remnant KGSA provided information that allowed us to predict remnant liver function. This information will be important for surgeons when deciding on a treatment plan for patients with liver diseases. (ClinicalTrials.gov ID: NCT02013895). Copyright © 2017 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Quality of care and investment in property, plant, and equipment in hospitals.

PubMed

Levitt, S W

1994-02-01

This study explores the relationship between quality of care and investment in property, plant, and equipment (PPE) in hospitals. Hospitals' investment in PPE was derived from audited financial statements for the fiscal years 1984-1989. Peer Review Organization (PRO) Generic Quality Screen (GQS) reviews and confirmed failures between April 1989 and September 1990 were obtained from the Massachusetts PRO. Weighted least squares regression models used PRO GQS confirmed failure rates as the dependent variable, and investment in PPE as the key explanatory variable. Investment in PPE was standardized, summed by the hospital over the six years, and divided by the hospital's average number of beds in that period. The number of PRO reviewed cases with one or more GQS confirmed failures was divided by the total number of cases reviewed to create confirmed failure rates. Investment in PPE in Massachusetts hospitals is correlated with GQS confirmed failure rates. A financial variable, investment in PPE, predicts certain dimensions of quality of care in hospitals.

Why Do Medial Unicompartmental Knee Arthroplasties Fail Today?

PubMed

van der List, Jelle P; Zuiderbaan, Hendrik A; Pearle, Andrew D

2016-05-01

Failure rates are higher in medial unicompartmental knee arthroplasty (UKA) than total knee arthroplasty. To improve these failure rates, it is important to understand why medial UKA fail. Because individual studies lack power to show failure modes, a systematic review was performed to assess medial UKA failure modes. Furthermore, we compared cohort studies with registry-based studies, early with midterm and late failures and fixed-bearing with mobile-bearing implants. Databases of PubMed, EMBASE, and Cochrane and annual registries were searched for medial UKA failures. Studies were included when they reported >25 failures or when they reported early (<5 years), midterm (5-10 years), or late failures (>10 years). Thirty-seven cohort studies (4 level II studies and 33 level III studies) and 2 registry-based studies were included. A total of 3967 overall failures, 388 time-dependent failures, and 1305 implant design failures were identified. Aseptic loosening (36%) and osteoarthritis (OA) progression (20%) were the most common failure modes. Aseptic loosening (26%) was most common early failure mode, whereas OA progression was more commonly seen in midterm and late failures (38% and 40%, respectively). Polyethylene wear (12%) and instability (12%) were more common in fixed-bearing implants, whereas pain (14%) and bearing dislocation (11%) were more common in mobile-bearing implants. This level III systematic review identified aseptic loosening and OA progression as the major failure modes. Aseptic loosening was the main failure mode in early years and mobile-bearing implants, whereas OA progression caused most failures in late years and fixed-bearing implants. Copyright © 2016 Elsevier Inc. All rights reserved.

Fatigue failure of the cephalomedullary nail: revision options, outcomes and review of the literature.

PubMed

Tucker, Adam; Warnock, Michael; McDonald, Sinead; Cusick, Laurence; Foster, Andrew P

2018-04-01

Cephalomedullary nail (CMN) failure is a rare entity following hip fracture treatment. However, it poses significant challenges for revision surgery, both mechanically and biologically. Nail failure rates have been reported at < 2%; however, no published studies have reported revision surgery procedures and their respective outcomes. We present a regional experience, with outcomes, of the revision options. We identified 20 fatigued CMNs that underwent four different revision procedures. Mean age was 73 ± 15.24 years, with a 3:1 female preponderance, and a median ASA grade of 3. Post-operative CMN radiographs demonstrated a significant number of fractures were fixed in varus, with reductions in neck-shaft angles post-operatively. A "poor" quality of reduction resulted in significantly earlier nail failure, compared to "adequate" and "good" (p = 0.027). Tip-Apex Distance (TAD) mean was 23.2 ± 8.3 mm, and an adequate TAD with three-point fixation was seen in only 35% of cases. Mean time to failure was 401.0 ± 237.2 days, with mean age at failure of 74.0 ± 14.8 years. Options after failure included revision CMN nail, proximal femoral locking plate (PFLP), long-stem or restoration arthroplasty, or femoral endoprosthesis. Barthel Functional Index scores showed no significant difference at 3 and 12 months post-operatively, nor any difference between treatment groups. Mean 12-month mortality was 30%, akin to a primary hip fracture mortality risk according to NICE guidelines. Mortality rates were lowest in revision nails. Subsequent revision rates were higher in the PFLP group. There is no reported evidence on the best surgical technique for managing the failed CMN, with no clear functional benefit in the options above. Good surgical technique at the time of primary CMN surgery is critical in minimising fatigue failure. After revision, overall mortality rates were equivalent to reported primary hip fracture mortality rates. Further multicentre evaluations are required to assess which technique convey the best functional outcomes without compromising 12-month mortality rates.

Pulmonary vasodilation in acute and chronic heart failure: empiricism and evidence.

PubMed

Guglin, Maya

2011-09-01

Pulmonary hypertension in heart failure is associated with exercise intolerance and adverse outcomes. With the availability of multiple drugs that cause pulmonary vasodilation and decrease pulmonary arterial pressure, pulmonary hypertension becomes an attractive therapeutic target. Out of several classes of medications, oral phosphodiesterase inhibitors emerge as the most promising in terms of symptomatic improvement, hemodynamic benefits, reverse cardiac remodeling, and functional capacity. Future trials will show whether the use of these drugs translates to decreased morbidity and mortality in heart failure.

Failure mechanisms in energy-absorbing composite structures

NASA Astrophysics Data System (ADS)

Johnson, Alastair F.; David, Matthew

2010-11-01

Quasi-static tests are described for determination of the energy-absorption properties of composite crash energy-absorbing segment elements under axial loads. Detailed computer tomography scans of failed specimens were used to identify local compression crush failure mechanisms at the crush front. These mechanisms are important for selecting composite materials for energy-absorbing structures, such as helicopter and aircraft sub-floors. Finite element models of the failure processes are described that could be the basis for materials selection and future design procedures for crashworthy structures.

Causes of catastrophic failure in complex systems

NASA Astrophysics Data System (ADS)

Thomas, David A.

2010-08-01

Root causes of mission critical failures and major cost and schedule overruns in complex systems and programs are studied through the post-mortem analyses compiled for several examples, including the Hubble Space Telescope, the Challenger and Columbia Shuttle accidents, and the Three Mile Island nuclear power plant accident. The roles of organizational complexity, cognitive biases in decision making, the display of quantitative data, and cost and schedule pressure are all considered. Recommendations for mitigating the risk of similar failures in future programs are also provided.

Sensor Data Qualification System (SDQS) Implementation Study

NASA Technical Reports Server (NTRS)

Wong, Edmond; Melcher, Kevin; Fulton, Christopher; Maul, William

2009-01-01

The Sensor Data Qualification System (SDQS) is being developed to provide a sensor fault detection capability for NASA s next-generation launch vehicles. In addition to traditional data qualification techniques (such as limit checks, rate-of-change checks and hardware redundancy checks), SDQS can provide augmented capability through additional techniques that exploit analytical redundancy relationships to enable faster and more sensitive sensor fault detection. This paper documents the results of a study that was conducted to determine the best approach for implementing a SDQS network configuration that spans multiple subsystems, similar to those that may be implemented on future vehicles. The best approach is defined as one that most minimizes computational resource requirements without impacting the detection of sensor failures.

Evaluation of sodium-nickel chloride cells for space applications

NASA Technical Reports Server (NTRS)

Hendel, B.; Dudley, G. J.

1991-01-01

The status of the European Space Agency (ESA) program on sodium nickel chloride batteries is outlined. Additionally, the results of initial tests of two prototype space cells are reported. After 2800 cycles typical of a low-earth orbit (LEO) application without failure, the recharge ratio remained at unity, the round trip energy efficiency remained high (87 percent), and the increase in internal cell resistance was modest. Initial tear-down analysis data show no degradation whatsoever of the beta-alumina electrolyte tubes. The low-rate capacity did, however drop by some 40 percent, which needs further investigation, but overall results are encouraging for future use of this couple in geosynchronous (GEO) and LEO spacecraft.

Critical analysis of 3-D organoid in vitro cell culture models for high-throughput drug candidate toxicity assessments.

PubMed

Astashkina, Anna; Grainger, David W

2014-04-01

Drug failure due to toxicity indicators remains among the primary reasons for staggering drug attrition rates during clinical studies and post-marketing surveillance. Broader validation and use of next-generation 3-D improved cell culture models are expected to improve predictive power and effectiveness of drug toxicological predictions. However, after decades of promising research significant gaps remain in our collective ability to extract quality human toxicity information from in vitro data using 3-D cell and tissue models. Issues, challenges and future directions for the field to improve drug assay predictive power and reliability of 3-D models are reviewed. Copyright © 2014 Elsevier B.V. All rights reserved.

The dose can make the poison: lessons learned from adverse in vivo toxicities caused by RNAi overexpression.

PubMed

Grimm, Dirk

2011-10-26

For the past five years, evidence has accumulated that vector-mediated robust RNA interference (RNAi) expression can trigger severe side effects in small and large animals, from cytotoxicity and accelerated tumorigenesis to organ failure and death. The recurring notions in these studies that a critical parameter is the strength of RNAi expression and that Exportin-5 and the Argonaute proteins are rate-limiting mammalian RNAi, strongly imply dose-dependent saturation of the endogenous miRNA pathway as one of the underlying mechanisms. This minireview summarizes the relevant work and data leading to this intriguing model and highlights potential avenues by which to alleviate RNAi-induced toxicities in future clinical applications.

Spherically Actuated Motor

NASA Technical Reports Server (NTRS)

Peeples, Steven

2015-01-01

A three degree of freedom (DOF) spherical actuator is proposed that will replace functions requiring three single DOF actuators in robotic manipulators providing space and weight savings while reducing the overall failure rate. Exploration satellites, Space Station payload manipulators, and rovers requiring pan, tilt, and rotate movements need an actuator for each function. Not only does each actuator introduce additional failure modes and require bulky mechanical gimbals, each contains many moving parts, decreasing mean time to failure. A conventional robotic manipulator is shown in figure 1. Spherical motors perform all three actuation functions, i.e., three DOF, with only one moving part. Given a standard three actuator system whose actuators have a given failure rate compared to a spherical motor with an equal failure rate, the three actuator system is three times as likely to fail over the latter. The Jet Propulsion Laboratory reliability studies of NASA robotic spacecraft have shown that mechanical hardware/mechanism failures are more frequent and more likely to significantly affect mission success than are electronic failures. Unfortunately, previously designed spherical motors have been unable to provide the performance needed by space missions. This inadequacy is also why they are unavailable commercially. An improved patentable spherically actuated motor (SAM) is proposed to provide the performance and versatility required by NASA missions.

Effect of bladder augmentation on VP shunt failure rates in spina bifida.

PubMed

Gonzalez, Dani O; Cooper, Jennifer N; McLeod, Daryl J

2017-12-11

Most patients with spina bifida require ventriculoperitoneal (VP) shunt placement. Some also require bladder augmentation, which may increase the risk of VP shunt malfunction and/or failure. The aim of this study was to assess whether bladder augmentation affects the rate of VP shunt failure in this population. Using the Pediatric Health Information System, we studied patients with spina bifida born between 1992 and 2014 who underwent VP shunt placement. Using conditional logistic regression, we compared age- and hospital-matched patients who did and did not undergo a bladder augmentation to determine their difference in rates of VP shunt failure. There were 4192 patients with spina bifida who underwent both surgical closure and VP shunt placement. Of these, 203 patients with bladder augmentation could be matched to 593 patients without bladder augmentation. VP shunt failure occurred within 2 years in 7.7% of patients, the majority of whom were in the group who underwent bladder augmentation (87%). After adjusting for confounders, undergoing bladder augmentation was independently associated with VP shunt failure (HR: 33.5, 95% CI: 13.15-85.44, p< 0.001). Bladder augmentation appears to be associated with VP shunt failure. Additional studies are necessary to better define this relationship and identify risk-reduction techniques.

Size effects and realiability of barium strontium titanate thin films

NASA Astrophysics Data System (ADS)

Parker, Charles Bernard

Thin films of (Ba,Sr)TiO3 (BST) deposited by Liquid Source MOCVD were investigated. BST is a candidate dielectric for future-generation DRAM and as a tunable dielectric. Two areas of both scientific and commercial interest were investigated. The first area is the effect of decreasing dimension on ferroelectric properties. Several theories of size effects in ferroelectrics were evaluated. The dielectric response of a set of BST films of thicknesses from 15 to 580 nm was measured from 85 to 580 K. These films were extensively characterized and the boundary conditions that often influence size effects measurements were considered, including strain, finite screening length in the electrode, depolarization fields in the ferroelectric, atmospheric effects, control of stochiometry, and others. The data set was compared to the theoretical predictions and it was determined that Finite Size Scaling provided the best fit to the data. Using this theory, the predicted dielectric response was compared to the requirements of future generations of DRAM and was found to be sufficient, if film strain can be controlled. The second area is reliability. The types of lifetime-limiting electrical failure observed in BST are resistance degradation, time dependant dielectric breakdown (tddb), and noisy breakdown. Previous work on BST reliability has largely focused on resistance degradation at high temperature. This condition is only a small subset of experimental space. This work extends the understanding of BST failure into the low temperature regime and evaluates the effects of both DC and AC stress. It was found that tddb is the dominant failure mode at low temperature and resistance degradation is the dominant failure modes at high temperature. Synthesizing this work with previous work on resistance degradation allowed a failure framework to be developed. Rigorous extrapolation of resistance degradation and tddb lifetimes was compared to the requirements of future generations of DRAM and was found that while resistance degradation will not limit device lifetimes, tddb will. Refinement of BST processing will be necessary to reduce the defect causing tddb failure.

Estimating the total incidence of kidney failure in Australia including individuals who are not treated by dialysis or transplantation.

PubMed

Sparke, Claire; Moon, Lynelle; Green, Frances; Mathew, Tim; Cass, Alan; Chadban, Steve; Chapman, Jeremy; Hoy, Wendy; McDonald, Stephen

2013-03-01

To date, incidence data for kidney failure in Australia have been available for only those who start renal replacement therapy (RRT). Information about the total incidence of kidney failure, including non-RRT-treated cases, is important to help understand the burden of kidney failure in the community and the characteristics of patients who die without receiving treatment. Data linkage study of national observational data sets. All incident treated cases recorded in the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) probabilistically linked to incident untreated kidney failure cases derived from national death registration data for 2003-2007. Age, sex, and year. Kidney failure, a combination of incident RRT or death attributed to kidney failure (without RRT). Total incidence of kidney failure (treated and untreated) and treatment rates. There were 21,370 incident cases of kidney failure in 2003-2007. The incidence rate was 20.9/100,000 population (95% CI, 18.3-24.0) and was significantly higher among older people and males (26.1/100,000 population; 95% CI, 22.5-30.0) compared with females (17.0/100,000 population; 95% CI, 14.9-19.2). There were similars number of treated (10,949) and untreated (10,421) cases, but treatment rates were influenced highly by age. More than 90% of cases in all age groups between 5 and 60 years were treated, but this percentage decreased sharply for older people; only 4% of cases in persons 85 years or older were treated (ORs for no treatment of 115 [95% CI, 118-204] for men ≥80 years and 400 [95% CI, 301-531] for women ≥80 years compared with women who were <50 years). Cross-sectional design, reliance on accurate coding of kidney failure in death registration data. Almost all Australians who develop kidney failure at younger than 60 years receive RRT, but treatment rates decrease substantially above that age. Copyright © 2013 National Kidney Foundation, Inc. All rights reserved.

Factors associated with dental implant survival: a 4-year retrospective analysis.

PubMed

Zupnik, Jamie; Kim, Soo-woo; Ravens, Daniel; Karimbux, Nadeem; Guze, Kevin

2011-10-01

Dental implants are a predictable treatment option for replacing missing teeth and have strong survival and success outcomes. However, previous research showed a wide array of potential risk factors that may have contributed to dental implant failures. The objectives of this study are to study if implant survival rates were affected by known risk factors and risk indicators that may have contributed to implant failures. The secondary outcome measures were whether the level of expertise of the periodontal residents affected success rates and how the rate of implant success at the Harvard School of Dental Medicine (HSDM) compared to published standards. A retrospective chart review of patients at the HSDM who had one of two types of rough-surface implants (group A or B) placed by periodontology residents from 2003 to 2006 was performed. Demographic, health, and implant data were collected and analyzed by multimodel analyses to determine failure rates and any factors that may have increased the likelihood of an implant failure. The study cohort included 341 dental implants. The odds ratio for an implant failure was most clearly elevated for diabetes (2.59 implant surface group B (7.84), and male groups (4.01). There was no significant difference regarding the resident experience. The success rate for HSDM periodontology residents was 96.48% during the 4-year study period. This study demonstrates that implant success rates at HSDM fell within accepted published standards, confirmed previously identified risk factors for a failure, and potentially suggested that other acknowledged risk factors could be controlled for. Furthermore, the level of experience of the periodontology resident did not have an impact on survival outcomes.

Survival rates of short (6 mm) micro-rough surface implants: a review of literature and meta-analysis.

PubMed

Srinivasan, Murali; Vazquez, Lydia; Rieder, Philippe; Moraguez, Osvaldo; Bernard, Jean-Pierre; Belser, Urs C

2014-05-01

The aim of this review was to test the hypothesis that 6 mm micro-rough short Straumann(®) implants provide predictable survival rates and verify that most failures occurring are early failures. A PubMed and hand search was performed to identify studies involving micro-rough 6-mm-short implants published between January 1987 and August 2011. Studies were included that (i) involve Straumann(®) 6 mm implants placed in the human jaws, (ii) provide data on the survival rate, (iii) mention the time of failure, and (iv) report a minimum follow-up period of 12 months following placement. A meta-analysis was performed on the extracted data. From a total of 842 publications that were screened, 12 methodologically sound articles qualified to be included for the statistical evaluation based on our inclusion criteria. A total of 690 Straumann(®) 6-mm-short implants were evaluated in the reviewed studies (Total: placed-690, failed-25; maxilla: placed-266, failed-14; mandible: placed-364, failed-5; follow-up period: 1-8 years). A meta-analysis was performed on the calculated early cumulative survival rates (CSR%). The pooled early CSR% calculated in this meta-analysis was 93.7%, whereas the overall survival rates in the maxilla and mandible were 94.7% and 98.6% respectively. Implant failures observed were predominantly early failures (76%). This meta-analysis provides robust evidence that micro-rough 6-mm-short dental implants are a predictable treatment option, providing favorable survival rates. The failures encountered with 6-mm-short implants were predominantly early and their survival in the mandible was slightly superior. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Dental implants in medically complex patients-a retrospective study.

PubMed

Manor, Yifat; Simon, Roy; Haim, Doron; Garfunkel, Adi; Moses, Ofer

2017-03-01

Dental implant insertion for oral rehabilitation is a worldwide procedure for healthy and medically compromised patients. The impact of systemic disease risks on the outcome of implant therapy is unclear, since there are few if any published randomized controlled trials (RCTs). The objective of this study is to investigate the rate of complications and failures following dental implantation in medically compromised patients in order to elucidate risk factors and prevent them. A retrospective cohort study was conducted from patient files treated with dental implantation between the years 2008-2014. The study group consisted of medically complex patients while the control group consisted of healthy patients. Preoperative, intraoperative, and post operative clinical details were retrieved from patients' files. The survival rate and the success rate of the dental implants were evaluated clinically and radiographically. A total of 204 patients (1003 dental implants) were included in the research, in the study group, 93 patients with 528 dental implants and in the control group, 111 patients with 475 dental implants. No significant differences were found between the groups regarding implant failures or complications. The failure rate of dental implants among the patients was 11.8 % in the study group and 16.2 % in the control group (P = 0.04). It was found that patients with a higher number of implants (mean 6.8) had failures compared with patients with a lower number of implants (mean 4.2) regardless of their health status (P < 0.01). We found a similar rate of failure and complications of dental implantation in medically complex patients and in healthy patients. Medically complex patients can undergo dental implantation. There are similar rates of complications and failures of dental implants in medically complex patients and in healthy patients.

Dronedarone: current evidence and future questions.

PubMed

Schafer, Jeremy A; Kjesbo, Nicole K; Gleason, Patrick P

2010-01-01

Atrial fibrillation (AF) is the most common sustained arrhythmia, affecting more than 2.2 million Americans. ACC/AHA/ESC guidelines for the management of patients with AF recommend amiodarone for maintaining sinus rhythm. Dronedarone is a derivative of amiodarone indicated for the treatment of AF. To provide an overview of dronedarone with a focus on the phase III trials and discuss unresolved questions of dronedarone. A literature search was conducted via the PubMed database using the keyword "dronedarone." Search was limited to human trials in english. The FDA website was searched for briefing documents and subcommittee meetings on dronedarone. Clinicaltrials.gov was searched with the keyword dronedarone for upcoming or unpublished clinical trials. Five phase III trials are available for dronedarone: ANDROMEDA, EURIDIS/ADONIS, ATHENA, ERATO, and DIONYSIS. EURIDIS/ADONIS and ATHENA demonstrated a reduction AF recurrence with dronedarone compared to placebo. The ANDROMEDA trial recruited patients with recent hospitalization for heart failure and was terminated due to an excess of deaths in the dronedarone group. The DIONYSIS trial was a comparative effectiveness trial that demonstrated less efficacy for dronedarone but improved tolerability compared to amiodarone. Dronedarone represents an option in the management of AF in select patients. Dronedarone is not appropriate in patients with recently decompensated heart failure or those treated with strong CYP3A4 inhibitors or medications prolonging the QT interval. Dronedarone appears to have improved tolerability at the expense of decreased efficacy when compared to amiodarone. Questions remain on the long-term safety, use in patients with heart failure, retreatment after dronedarone or amiodarone failure, and comparative efficacy with a rate control strategy.

Quantification of Road Network Vulnerability and Traffic Impacts to Regional Landslide Hazards.

NASA Astrophysics Data System (ADS)

Postance, Benjamin; Hillier, John; Dixon, Neil; Dijkstra, Tom

2015-04-01

Slope instability represents a prevalent hazard to transport networks. In the UK regional road networks are frequently disrupted by multiple slope failures triggered during intense precipitation events; primarily due to a degree of regional homogeneity of slope materials, geomorphology and weather conditions. It is of interest to examine how different locations and combinations of slope failure impact road networks, particularly in the context of projected climate change and a 40% increase in UK road demand by 2040. In this study an extensive number (>50 000) of multiple failure event scenarios are simulated within a dynamic micro simulation to assess traffic impacts during peak flow (7 - 10 AM). Possible failure locations are selected within the county of Gloucestershire (3150 km2) using historic failure sites and British Geological Survey GeoSure data. Initial investigations employ a multiple linear regression analyses to consider the severity of traffic impacts, as measured by time, in respect of spatial and topographical network characteristics including connectivity, density and capacity in proximity to failure sites; the network distance between disruptions in multiple failure scenarios is used to consider the effects of spatial clustering. The UK Department of Transport road travel demand and UKCP09 weather projection data to 2080 provide a suitable basis for traffic simulations and probabilistic slope stability assessments. Future work will thus focus on the development of a catastrophe risk model to simulate traffic impacts under various narratives of future travel demand and slope instability under climatic change. The results of this investigation shall contribute to the understanding of road network vulnerabilities and traffic impacts from climate driven slope hazards.

The complex nature of informal care in home-based heart failure management.

PubMed

Clark, Alexander M; Reid, Margaret E; Morrison, Caroline E; Capewell, Simon; Murdoch, David L; McMurray, John J

2008-02-01

This paper is a report of a study to examine the complexities of informal caregiving for people with chronic heart failure. Little is known of the activities involved and underlying informal care. Heart failure is a common and burdensome condition in which carers play an important management role. Semi-structured interviews were carried out with 30 informal carers nominated by patients with mild-to-moderate heart failure (24 spouses, four children, one sibling and one neighbour). Interviews examined knowledge of heart failure, its effects, reported management practices and concerns, decision making and support. The data were collected in 2001. The management of heart failure was a shared and ongoing responsibility between the carer and patient. Carers' clinical knowledge of the condition and management was often limited, but they developed extensive knowledge of its personal effects on the patient. Invisible care activities included monitoring signs of symptom exacerbation and energy boundaries against perceived current and future demands and priorities. Visible care activities included medication management, dressing, bathing and help-seeking. Carers responded to patients' capacities, and adopted philosophies that sought to foster independence while facilitating as normal a life for the patient as was possible and safe. Interventions for informal carers around effective chronic heart failure management should address both visible and invisible informal caring. Future research is needed to develop interventions with carers to improve quality of care, reduce costs and improve patient quality of life. More research is needed to explore the complexities of lay caregiving and to explore the invisible dimensions of informal care further.

An Experimental Investigation of Silicone-to-Metal Bond Strength in Composite Space Docking System Seals

NASA Technical Reports Server (NTRS)

Gaier, James R.; Siamidis, John; Larkin, Elizabeth M. G.

2010-01-01

The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions called the Low Impact Docking System (LIDS). A candidate LIDS main interface seal design is a composite assembly of silicone elastomer seals vacuum molded into grooves in an electroless nickel plated aluminum retainer. The strength of the silicone-tometal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created during the molding process. In the work presented herein, seal-to-retainer bonds of subscale seal specimens with different sizes of intentional disbond were destructively tensile tested. Nominal specimens without intentional disbonds were also tested. Tension was applied either uniformly on the entire seal circumference or locally in one short circumferential length. Bond failure due to uniform tension produced a wide scatter of observable failure modes and measured load-displacement behaviors. Although the preferable failure mode for the seal-to-retainer bond is cohesive failure of the elastomer material, the dominant observed failure mode under the uniform loading condition was found to be the less desirable adhesive failure of the bond in question. The uniform tension case results did not show a correlation between disbond size and bond strength. Localized tension was found to produce failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal in one piece. The obtained results represent a valuable benchmark for comparison in the future between adhesion loads under various separation conditions and composite seal bond strength.

Factors associated with the caregiver burden among family caregivers of patients with heart failure in southwest China.

PubMed

Hu, Xiaolin; Dolansky, Mary A; Hu, Xiuying; Zhang, Fengying; Qu, Moying

2016-03-01

We investigated the status of caregiver burden and identified the factors related to caregiver burden among family caregivers of patients with heart failure in southwest China. A cross-sectional descriptive design with a convenience sample was adopted. Patient and family caregiver dyads (n = 226) in four hospitals in Chengdu, China were recruited from June 2013 to July 2014. The instruments used in this study included the Social Support Rating Scale, the Zarit Burden Interview, and the General Self-Efficacy Scale. Multivariate analysis was used to identify the factors associated with caregiver burden. Forty-four percent of the variance of the caregiver burden was explained by the payment type for treatment, monthly family income, relationship to the patient, caregivers' self-efficacy, and social support. The caregiver burden in southwest China was higher than studies conducted in developed areas. Specific to southwest China, the financial burden and insufficient resources are the main factors associated with caregiver burden. The results suggest that self-efficacy and social support in underdeveloped areas are potential areas for future intervention. © 2016 John Wiley & Sons Australia, Ltd.

Induction of labor in elderly nulliparous women.

PubMed

Hadar, Eran; Hiersch, Liran; Ashwal, Eran; Chen, Rony; Wiznitzer, Arnon; Gabbay-Benziv, Rinat

2017-09-01

Maternal age is an important consideration for antenatal care, labor and delivery. We aimed to evaluate the induction of labor (IoL) failure rates among elderly nulliparous women. We conducted a retrospective analysis of all nulliparous women at 34 + 0 to 41 + 6 weeks, undergoing cervical ripening by prostaglandin E2 (PGE2) vaginal insert. Study group included elderly (≥35 years) nulliparous and control group included non-elderly (<35 years) nulliparous women. Primary outcome was IoL failure rate and secondary outcome was cesarean delivery rate. Outcomes were compared between the groups by univariate analysis followed by regression analysis to adjust results to potential confounders. Of 537 women undergoing IoL, 69 (12.8%) were elderly. The univariate analysis demonstrated no difference in IoL failure rate (26.5% versus 34.8%, p = 0.502) between groups. However, elderly nulliparous women had higher rates of cesarean delivery (36.2% versus 21.4%, p = 0.009). This difference was no longer significant after adjustment for maternal body mass index, indication for delivery, birth weight and gestational age at delivery. Among nulliparous women, older maternal age is not associated with higher rates of IoL failure or cesarean deliveries.

Recent and future warm extreme events and high-mountain slope stability.

PubMed

Huggel, C; Salzmann, N; Allen, S; Caplan-Auerbach, J; Fischer, L; Haeberli, W; Larsen, C; Schneider, D; Wessels, R

2010-05-28

The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future. Although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied, the impacts of short-term, unusually warm temperature increases on slope stability in high mountains remain largely unexplored. We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing. We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001-2050 compared with a 1951-2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5-4 times by 2050 and in some models by up to 10 times. Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw. Although these processes reduce slope strength, they must be considered within the local geological, glaciological and topographic context of a slope.

Effect of hierarchy legitimacy on low status group members' attributions for ingroup and outgroup failures.

PubMed

Beatson, Ruth M; Halloran, Michael J

2015-04-01

Previous research has shown that people have a tendency to explain successes and failures in ways that favor their ingroups relative to outgroups. However, there has been a dearth of research examining whether social-contextual factors such as group status and hierarchy legitimacy moderate such intergroup attributions. Participants in this study were assigned to a low status group, and perceived hierarchy legitimacy was then experimentally manipulated; the extent to which ingroup versus outgroup failures were attributed to several causes was measured. When low status was considered illegitimate, ingroup failure was attributed to external causes (task difficulty, bad luck) more so than outgroup failure. Implications and directions for future research examining consequences and mediating processes are discussed.

Size Constraints on Late Miocene to Pliocene Submarine Slope Failures along the Colombian Caribbean Subduction Margin as a Basis for Assessing Circum-Caribbean Impact of Future Tsunami Events

NASA Astrophysics Data System (ADS)

Leslie, S.; Mann, P.

2015-12-01

The Colombian Caribbean margin provides an ideal setting for the formation of large mass transport deposits (MTDs): 1) the Caribbean Plate is slowly subducting at rates of 20 mm/yr with infrequent large thrust earthquakes and a complete lack of subduction events in the 400-year-long historical record; 2) the margin is a broad zone of active faults including a ~50 km-wide accretionary prism and strike-slip faults landward of the prism; 3) the active margin is draped by the Magdalena delta and submarine fan fed by the Magdalena River, the 26th largest in the world; and 4) the margin is over-steepened to slopes of up to 7° from the combination of tectonic activity and rapid rates of deltaic progradation. Using seismic data we have identified three late Miocene-Pliocene MTDs, the largest of which is between 4500 and 6000 km3, comparable in size to the well-studied Storegga slide of Norway. The tsunamigenic potential of future, analog MTD events are modeled using GeoWave tsunami modeling software. The largest and youngest of these MTDs, the Santa Marta slide, is used as an analog to infer the location and input parameters for the tsunami model. The event is modeled as a translational slide ~46 km long and ~37 km wide with the center of the slide located ~57 km W/NW from the mouth of the present day Magdalena River in water depths of 1500 m. The volume for the initial failure is conservatively estimated at ~680 km3 of material. The resulting tsunami wave from such an event has an initial maximum trough amplitude of -65.8 m and a peak amplitude of 19.2 m. The impact of such a tsunami would include: 1) Kingston, Jamaica (population 938K), tsunami height 7.5 m, peak arrival at 60 min.; 2) Santo Domingo, Dominican Republic (population 965K, height 6 m, peak arrival at 80 min.); and 3) Cartagena, Colombia (population 845K, height 21 m, peak arrival at 34 min.). A number of parameters to the model are varied to analyze sensitivity of modeling results to changes in slide depth, angle of failure, slide volume, and slide density.

Predicting Honeybee Colony Failure: Using the BEEHAVE Model to Simulate Colony Responses to Pesticides

PubMed Central

2015-01-01

To simulate effects of pesticides on different honeybee (Apis mellifera L.) life stages, we used the BEEHAVE model to explore how increased mortalities of larvae, in-hive workers, and foragers, as well as reduced egg-laying rate, could impact colony dynamics over multiple years. Stresses were applied for 30 days, both as multiples of the modeled control mortality and as set percentage daily mortalities to assess the sensitivity of the modeled colony both to small fluctuations in mortality and periods of low to very high daily mortality. These stresses simulate stylized exposure of the different life stages to nectar and pollen contaminated with pesticide for 30 days. Increasing adult bee mortality had a much greater impact on colony survival than mortality of bee larvae or reduction in egg laying rate. Importantly, the seasonal timing of the imposed mortality affected the magnitude of the impact at colony level. In line with the LD50, we propose a new index of “lethal imposed stress”: the LIS50 which indicates the level of stress on individuals that results in 50% colony mortality. This (or any LISx) is a comparative index for exploring the effects of different stressors at colony level in model simulations. While colony failure is not an acceptable protection goal, this index could be used to inform the setting of future regulatory protection goals. PMID:26444386

The influence of regional hydrology on nesting behavior and nest fate of the American alligator

USGS Publications Warehouse

Ugarte, Cristina A.; Bass, Oron L.; Nuttle, William; Mazzotti, Frank J.; Rice, Kenneth G.; Fujisaki, Ikuko; Whelan, Kevin R.T.

2013-01-01

Hydrologic conditions are critical to the nesting behavior and reproductive success of crocodilians. In South Florida, USA, growing human settlement has led to extensive surface water management and modification of historical water flows in the wetlands, which have affected regional nesting of the American alligator (Alligator mississippiensis). Although both natural and anthropogenic factors are considered to determine hydrologic conditions, the aspects of hydrological patterns that affect alligator nest effort, flooding (partial and complete), and failure (no hatchling) are unclear. We deconstructed annual hydrological patterns using harmonic models that estimated hydrological matrices including mean, amplitude, timing of peak, and periodicity of surface water depth and discharge and examined their effects on alligator nesting using survey data from Shark Slough, Everglades National Park, from 1985 to 2005. Nest effort increased in years with higher mean and lesser periodicity of water depth. A greater proportion of nests were flooded and failed when peak discharge occurred earlier in the year. Also, nest flooding rates were greater in years with greater periodicity of water depth, and nest failure rate was greater when mean discharge was higher. This study guides future water management decisions to mitigate negative impacts on reproduction of alligators and provides wildlife managers with a tool for assessing and modifying annual water management plans to conserve crocodilians and other wetland species.

Mind-Body Interventions for Individuals With Heart Failure: A Systematic Review of Randomized Trials.

PubMed

Gok Metin, Zehra; Ejem, Deborah; Dionne-Odom, J Nicholas; Turkman, Yasemin; Salvador, Carolina; Pamboukian, Salpy; Bakitas, Marie

2018-03-01

The effects of mind-body interventions (MBIs) (eg, Tai Chi, yoga, meditation) for individuals with heart failure (HF) have not been systematically evaluated. We performed a systematic review of randomized controlled trials (RCTs) examining the effects of MBIs in HF. We extracted participant characteristics, MBI procedure, outcomes assessed, and main results of English-language RCTs before October 2016. We identified 24 RCTs (n = 1314 participants) of 9 MBI types: Tai Chi (n = 7), yoga (n = 4), relaxation (n = 4), meditation (n = 2), acupuncture (n = 2), biofeedback (n = 2), stress management (n = 1), Pilates (n = 1), and reflexology (n = 1). Most (n = 22, 95.8%) reported small-to-moderate improvements in quality of life (14/14 studies), exercise capacity (8/9 studies), depression (5/5 studies), anxiety and fatigue (4/4 studies), blood pressure (3/5 studies), heart rate (5/6 studies), heart rate variability (7/9 studies), and B-type natriuretic peptide (3/4 studies). Studies ranged from 4 minutes to 26 weeks and group sizes ranged from 8 to 65 patients per study arm. Although wide variability exists in the types and delivery, RCTs of MBIs have demonstrated small-to-moderate positive effects on HF patients' objective and subjective outcomes. Future research should examine the mechanisms by which different MBIs exert their effects. Copyright © 2017 Elsevier Inc. All rights reserved.

Forecasting the impact of heart failure in the United States: a policy statement from the American Heart Association.

PubMed

Heidenreich, Paul A; Albert, Nancy M; Allen, Larry A; Bluemke, David A; Butler, Javed; Fonarow, Gregg C; Ikonomidis, John S; Khavjou, Olga; Konstam, Marvin A; Maddox, Thomas M; Nichol, Graham; Pham, Michael; Piña, Ileana L; Trogdon, Justin G

2013-05-01

Heart failure (HF) is an important contributor to both the burden and cost of national healthcare expenditures, with more older Americans hospitalized for HF than for any other medical condition. With the aging of the population, the impact of HF is expected to increase substantially. We estimated future costs of HF by adapting a methodology developed by the American Heart Association to project the epidemiology and future costs of HF from 2012 to 2030 without double counting the costs attributed to comorbid conditions. The model assumes that HF prevalence will remain constant by age, sex, and race/ethnicity and that rising costs and technological innovation will continue at the same rate. By 2030, >8 million people in the United States (1 in every 33) will have HF. Between 2012 and 2030, real (2010$) total direct medical costs of HF are projected to increase from $21 billion to $53 billion. Total costs, including indirect costs for HF, are estimated to increase from $31 billion in 2012 to $70 billion in 2030. If one assumes all costs of cardiac care for HF patients are attributable to HF (no cost attribution to comorbid conditions), the 2030 projected cost estimates of treating patients with HF will be 3-fold higher ($160 billion in direct costs). The estimated prevalence and cost of care for HF will increase markedly because of aging of the population. Strategies to prevent HF and improve the efficiency of care are needed.

The Predictive Value of Indocyanine Green Clearance in Future Liver Remnant for Posthepatectomy Liver Failure Following Hepatectomy with Extrahepatic Bile Duct Resection.

PubMed

Yokoyama, Yukihiro; Ebata, Tomoki; Igami, Tsuyoshi; Sugawara, Gen; Mizuno, Takashi; Yamaguchi, Junpei; Nagino, Masato

2016-06-01

Postoperative liver failure (PHLF) is one of the most common complications following major hepatectomy. The preoperative assessment of future liver remnant (FLR) function is critical to predict the incidence of PHLF. To determine the efficacy of the plasma clearance rate of indocyanine green clearance of FLR (ICGK-F) in predicting PHLF in cases of highly invasive hepatectomy with extrahepatic bile duct resection. Five hundred and eighty-five patients who underwent major hepatectomy with extrahepatic bile duct resection, from 2002 to 2014 in a single institution, were evaluated. Among them, 192 patients (33 %) had PHLF. The predictive value of ICGK-F for PHLF was determined and compared with other risk factors for PHLF. The incidence of PHLF was inversely proportional to the level of ICGK-F. With multivariate logistic regression analysis, ICGK-F, combined pancreatoduodenectomy, the operation time, and blood loss were identified as independent risk factors of PHLF. The risk of PHLF increased according to the decrement of ICGK-F (the odds ratio of ICGK-F for each decrement of 0.01 was 1.22; 95 % confidence interval 1.12-1.33; P < 0.001). Low ICGK-F was also identified as an independent risk factor predicting the postoperative mortality. ICGK-F is useful in predicting the PHLF and mortality in patients undergoing major hepatectomy with extrahepatic bile duct resection. This criterion may be useful for highly invasive hepatectomy, such as that with extrahepatic bile duct resection.

Forecasting the Impact of Heart Failure in the United States

PubMed Central

Heidenreich, Paul A.; Albert, Nancy M.; Allen, Larry A.; Bluemke, David A.; Butler, Javed; Fonarow, Gregg C.; Ikonomidis, John S.; Khavjou, Olga; Konstam, Marvin A.; Maddox, Thomas M.; Nichol, Graham; Pham, Michael; Piña, Ileana L.; Trogdon, Justin G.

2013-01-01

Background Heart failure (HF) is an important contributor to both the burden and cost of national healthcare expenditures, with more older Americans hospitalized for HF than for any other medical condition. With the aging of the population, the impact of HF is expected to increase substantially. Methods and Results We estimated future costs of HF by adapting a methodology developed by the American Heart Association to project the epidemiology and future costs of HF from 2012 to 2030 without double counting the costs attributed to comorbid conditions. The model assumes that HF prevalence will remain constant by age, sex, and race/ethnicity and that rising costs and technological innovation will continue at the same rate. By 2030, >8 million people in the United States (1 in every 33) will have HF. Between 2012 and 2030, real (2010$) total direct medical costs of HF are projected to increase from $21 billion to $53 billion. Total costs, including indirect costs for HF, are estimated to increase from $31 billion in 2012 to $70 billion in 2030. If one assumes all costs of cardiac care for HF patients are attributable to HF (no cost attribution to comorbid conditions), the 2030 projected cost estimates of treating patients with HF will be 3-fold higher ($160 billion in direct costs). Conclusions The estimated prevalence and cost of care for HF will increase markedly because of aging of the population. Strategies to prevent HF and improve the efficiency of care are needed. PMID:23616602

Rate based failure detection

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

Johnson, Brett Emery Trabun; Gamage, Thoshitha Thanushka; Bakken, David Edward

This disclosure describes, in part, a system management component and failure detection component for use in a power grid data network to identify anomalies within the network and systematically adjust the quality of service of data published by publishers and subscribed to by subscribers within the network. In one implementation, subscribers may identify a desired data rate, a minimum acceptable data rate, desired latency, minimum acceptable latency and a priority for each subscription. The failure detection component may identify an anomaly within the network and a source of the anomaly. Based on the identified anomaly, data rates and or datamore » paths may be adjusted in real-time to ensure that the power grid data network does not become overloaded and/or fail.« less

Quantifying Appropriate De-rating of SiC MOSFETs Subject to Cosmic Rays

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

Chatty, Kiran

Terrestrial Cosmic Radiation (TCR) is known to cause failures in high-voltage Si devices resulting in de-rating of the maximum reverse blocking voltage. In this work, a test setup was developed and unaccelerated TCR testing was performed on 1200V Si IGBTs, 1200V SiC MOSFETs and 1200V SiC Schottky diodes. Failures due to TCR were generated on 1200V Si IGBTs at reverse voltages from 900V to 1175V. Si IGBTs investigated in this work will need to be operated at a maximum voltage of 800V to achieve a Failure in Time (FIT) rate of 100. No failures were observed on 1200V SiC MOSFETsmore » and Schottky diodes after testing at 1200V for over 1.5 years demonstrating low FIT rates compared to Si IGBTs. 1200V SiC Schottky diodes were fabricated in this program and the packaged devices were used in the TCR testing.« less

Predictions of High Strain Rate Failure Modes in Layered Aluminum Composites

NASA Astrophysics Data System (ADS)

Khanikar, Prasenjit; Zikry, M. A.

2014-01-01

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

Analysis of Failures of High Speed Shaft Bearing System in a Wind Turbine

NASA Astrophysics Data System (ADS)

Wasilczuk, Michał; Gawarkiewicz, Rafał; Bastian, Bartosz

2018-01-01

During the operation of wind turbines with gearbox of traditional configuration, consisting of one planetary stage and two helical stages high failure rate of high speed shaft bearings is observed. Such a high failures frequency is not reflected in the results of standard calculations of bearing durability. Most probably it can be attributed to atypical failure mechanism. The authors studied problems in 1.5 MW wind turbines of one of Polish wind farms. The analysis showed that the problems of high failure rate are commonly met all over the world and that the statistics for the analysed turbines were very similar. After the study of potential failure mechanism and its potential reasons, modification of the existing bearing system was proposed. Various options, with different bearing types were investigated. Different versions were examined for: expected durability increase, extent of necessary gearbox modifications and possibility to solve existing problems in operation.

Quantitative method of medication system interface evaluation.

PubMed

Pingenot, Alleene Anne; Shanteau, James; Pingenot, James D F

2007-01-01

The objective of this study was to develop a quantitative method of evaluating the user interface for medication system software. A detailed task analysis provided a description of user goals and essential activity. A structural fault analysis was used to develop a detailed description of the system interface. Nurses experienced with use of the system under evaluation provided estimates of failure rates for each point in this simplified fault tree. Means of estimated failure rates provided quantitative data for fault analysis. Authors note that, although failures of steps in the program were frequent, participants reported numerous methods of working around these failures so that overall system failure was rare. However, frequent process failure can affect the time required for processing medications, making a system inefficient. This method of interface analysis, called Software Efficiency Evaluation and Fault Identification Method, provides quantitative information with which prototypes can be compared and problems within an interface identified.

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

Daniel, Isaac M.

To facilitate and accelerate the process of introducing, evaluating and adopting of new material systems, it is important to develop/establish comprehensive and effective procedures of characterization, modeling and failure prediction of structural laminates based on the properties of the constituent materials, e. g., fibers, matrix, and the single ply or lamina. A new failure theory, the Northwestern (NU-Daniel) theory, has been proposed for predicting lamina yielding and failure under multi-axial states of stress including strain rate effects. It is primarily applicable to matrix-dominated interfiber/interlaminar failures. It is based on micromechanical failure mechanisms but is expressed in terms of easily measuredmore » macroscopic lamina stiffness and strength properties. It is presented in the form of a master failure envelope incorporating strain rate effects. The theory was further adapted and extended to the prediction of in situ first ply yielding and failure (FPY and FPF) and progressive failure of multi-directional laminates under static and dynamic loadings. The significance of this theory is that it allows for rapid screening of new composite materials without very extensive testing and offers easily implemented design tools.« less

Poor Response to Periodontal Treatment May Predict Future Cardiovascular Disease.

PubMed

Holmlund, A; Lampa, E; Lind, L

2017-07-01

Periodontal disease has been associated with cardiovascular disease (CVD), but whether the response to the treatment of periodontal disease affects this association has not been investigated in any large prospective study. Periodontal data obtained at baseline and 1 y after treatment were available in 5,297 individuals with remaining teeth who were treated at a specialized clinic for periodontal disease. Poor response to treatment was defined as having >10% sites with probing pocket depth >4 mm deep and bleeding on probing at ≥20% of the sites 1 y after active treatment. Fatal/nonfatal incidence rate of CVD (composite end point of myocardial infarction, stroke, and heart failure) was obtained from the Swedish cause-of-death and hospital discharge registers. Poisson regression analysis was performed to analyze future risk of CVD. During a median follow-up of 16.8 y (89,719 person-years at risk), those individuals who did not respond well to treatment (13.8% of the sample) had an increased incidence of CVD ( n = 870) when compared with responders (23.6 vs. 15.3%, P < 0.001). When adjusting for calendar time, age, sex, educational level, smoking, and baseline values for bleeding on probing, probing pocket depth >4 mm, and number of teeth, the incidence rate ratio for CVD among poor responders was 1.28 (95% CI, 1.07 to 1.53; P = 0.007) as opposed to good responders. The incidence rate ratio among poor responders increased to 1.39 (95% CI, 1.13 to 1.73; P = 0.002) for those with the most remaining teeth. Individuals who did not respond well to periodontal treatment had an increased risk for future CVD, indicating that successful periodontal treatment might influence progression of subclinical CVD.

Test effectiveness study report: An analytical study of system test effectiveness and reliability growth of three commercial spacecraft programs

NASA Technical Reports Server (NTRS)

Feldstein, J. F.

1977-01-01

Failure data from 16 commercial spacecraft were analyzed to evaluate failure trends, reliability growth, and effectiveness of tests. It was shown that the test programs were highly effective in ensuring a high level of in-orbit reliability. There was only a single catastrophic problem in 44 years of in-orbit operation on 12 spacecraft. The results also indicate that in-orbit failure rates are highly correlated with unit and systems test failure rates. The data suggest that test effectiveness estimates can be used to guide the content of a test program to ensure that in-orbit reliability goals are achieved.

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

PubMed

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

2015-01-01

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

Prediction of scuffing failure based on competitive kinetics of oxide formation and removal: Application to lubricated sliding of AISI 52100 steel on steel

NASA Astrophysics Data System (ADS)

Cutiongco, Eric C.; Chung, Yip-Wah

1994-07-01

A method for predicting scuffing failure based on the competitive kinetics of oxide formation and removal has been developed and applied to the sliding of AISI 52100 steel on steel with poly-alpha-olefin as the lubricant. Oxide formation rates were determining using static oxidation tests on coupons of 52100 steel covered with poly-alpha-olefin at temperatures of 140 C to 250 C. Oxide removal rates were determined at different combinations of initial average nominal contact pressures (950 MPa to 1578 MPa) and sliding velocities (0.4 m/s to 1.8 m/s) using a ball-on-disk vacuum tribotester. The nominal asperity flash temperatures generated during the wear tests were calculated and the temperatures corresponding to the intersection of the the Arrhenius plots of oxide formation and removal rates were determined and taken as the critical failure temperatures. The pressure-velocity failure transition diagram was constructed by plotting the critical failure temperatures along isotherms of average nominal asperity flash temperatures calculated at different combinations of contact stress and sliding speed. The predicted failure transition curve agreed well with experimental scuffing data.

Mumps resurgences in the United States: A historical perspective on unexpected elements.

PubMed

Barskey, Albert E; Glasser, John W; LeBaron, Charles W

2009-10-19

In 2006 the United States experienced the largest nationwide mumps epidemic in 20 years, primarily affecting college dormitory residents. Unexpected elements of the outbreak included very abrupt time course (75% of cases occurred within 90 days), geographic focality (85% of cases occurred in eight rural Midwestern states), rapid upward and downward shift in peak age-specific attack rate (5-9-year olds to 18-24-year olds, then back), and two-dose vaccine failure (63% of case-patients had received two doses). To construct a historical context in which to understand the recent outbreak, we reviewed US mumps surveillance data, vaccination coverage estimates, and relevant peer-reviewed literature for the period 1917-2008. Many of the unexpected features of the 2006 mumps outbreak had been reported several times previously in the US, e.g., the 1986-1987 mumps resurgence had extremely abrupt onset, rural geographic focality, and an upward-then-downward age shift. Evidence suggested recurrent mumps outbreak patterns were attributable to accumulation of susceptibles in dispersed situations where the risk of endemic disease exposure was low and were triggered when this susceptible population was brought together in crowded living conditions. The 2006 epidemic followed this pattern, with two unique variations: it was preceded by a period of very high vaccination rates and very low disease incidence and was characterized by two-dose failure rates among adults vaccinated in childhood. Data from the past 80 years suggest that preventing future mumps epidemics will depend on innovative measures to detect and eliminate build-up of susceptibles among highly vaccinated populations.

The Oxford unicompartmental knee fails at a high rate in a high-volume knee practice.

PubMed

Schroer, William C; Barnes, C Lowry; Diesfeld, Paul; LeMarr, Angela; Ingrassia, Rachel; Morton, Diane J; Reedy, Mary

2013-11-01

The Oxford knee is a unicompartmental implant featuring a mobile-bearing polyethylene component with excellent long-term survivorship results reported by the implant developers and early adopters. By contrast, other studies have reported higher revision rates in large academic practices and in national registries. Registry data have shown increased failure with this implant especially by lower-volume surgeons and institutions. In the setting of a high-volume knee arthroplasty practice, we sought to determine (1) the failure rate of the Oxford unicompartmental knee implant using a failure definition for aseptic loosening that combined clinical features, plain radiographs, and scintigraphy, and (2) whether increased experience with this implant would decrease failure rate, if there is a learning curve effect. Eighty-three Oxford knee prostheses were implanted between September 2005 and July 2008 by the principal investigator. Radiographic and clinical data were available for review for all cases. A failed knee was defined as having recurrent pain after an earlier period of recovery from surgery, progressive radiolucent lines compared with initial postoperative radiographs, and a bone scan showing an isolated area of uptake limited to the area of the replaced compartment. Eleven knees in this series failed (13%); Kaplan-Meier survivorship was 86.5% (95% CI, 78.0%-95.0%) at 5 years. Failure occurrences were distributed evenly over the course of the study period. No learning curve effect was identified. Based on these findings, including a high failure rate of the Oxford knee implant and the absence of any discernible learning curve effect, the principal investigator no longer uses this implant.

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.

A prospective study of risk factors and historical trends in metronidazole failure for Clostridium difficile infection

PubMed Central

Hu, Mary Y.; Maroo, Seema; Kyne, Lorraine; Cloud, Jeffrey; Tummala, Sanjeev; Katchar, Kianoosh; Dreisbach, Valley; Noddin, Laura; Kelly, Ciarán P.

2009-01-01

Background & Aims Recent studies of C. difficile infection (CDI) indicate a dramatic increase in metronidazole failure. The aims of this study were to compare current and historical rates of metronidazole failure and identify risk factors for metronidazole failure. Methods 89 patients with CDI in 2004–2006 were followed for 60 days. Data were compared to a historical cohort of 63 CDI patients studied prospectively in 1998. Metronidazole failure was defined as persistent diarrhea after 10 days of therapy or a change of therapy to vancomycin. Stool samples were analyzed for the presence of NAP-1 strain. Results Metronidazole failure rates were 35% in both the 1998 and 2004–2006 cohorts. There was no difference in the median time to resolution of diarrhea (8 vs. 5 days, p = 0.52) or the proportion with more than 10 days of diarrhea (35% vs. 29%, p = 0.51). Risk factors for metronidazole failure included recent cephalosporin use (OR 32, 95% CI 5–219), CDI on admission (OR 23, 95% CI 3–156), and transfer from another hospital (OR 11, 95% CI 2–72). The frequency of NAP-1 infection in patients with and without metronidazole failure was similar (26% vs. 21%, p = 0.67). Conclusions We found no difference in metronidazole failure rates in 1998 and 2004–2006. Patients with recent cephalosporin use, CDI on admission, and transfer from another hospital were more likely to fail metronidazole and may benefit from early aggressive therapy. Infection with the epidemic NAP-1 strain was not associated with metronidazole failure in endemic CDI. PMID:19081526

Association between First Nations ethnicity and progression to kidney failure by presence and severity of albuminuria.

PubMed

Samuel, Susan M; Palacios-Derflingher, Luz; Tonelli, Marcello; Manns, Braden; Crowshoe, Lynden; Ahmed, Sofia B; Jun, Min; Saad, Nathalie; Hemmelgarn, Brenda R

2014-02-04

Despite a low prevalence of chronic kidney disease (estimated glomerular filtration rate [GFR]<60 mL/min per 1.73 m2), First Nations people have high rates of kidney failure requiring chronic dialysis or kidney transplantation. We sought to examine whether the presence and severity of albuminuria contributes to the progression of chronic kidney disease to kidney failure among First Nations people. We identified all adult residents of Alberta (age≥18 yr) for whom an outpatient serum creatinine measurement was available from May 1, 2002, to Mar. 31, 2008. We determined albuminuria using urine dipsticks and categorized results as normal (i.e., no albuminuria), mild, heavy or unmeasured. Our primary outcome was progression to kidney failure (defined as the need for chronic dialysis or kidney transplantation, or a sustained doubling of serum creatinine levels). We calculated rates of progression to kidney failure by First Nations status, by estimated GFR and by albuminuria category. We determined the relative hazard of progression to kidney failure for First Nations compared with non-First Nations participants by level of albuminuria and estimated GFR. Of the 1 816 824 participants we identified, 48 669 (2.7%) were First Nations. First Nations people were less likely to have normal albuminuria compared with non-First Nations people (38.7% v. 56.4%). Rates of progression to kidney failure were consistently 2- to 3-fold higher among First Nations people than among non-First Nations people, across all levels of albuminuria and estimated GFRs. Compared with non-First Nations people, First Nations people with an estimated GFR of 15.0-29.9 mL/min per 1.73 m2 had the highest risk of progression to kidney failure, with similar hazard ratios for those with normal and heavy albuminuria. Albuminuria confers a similar risk of progression to kidney failure for First Nations and non-First Nations people.

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

Menikoff, Ralph

SURFplus is a reactive burn model for high explosives aimed at modelling shock initiation and propagation of detonation waves. It utilizes the SURF model for the fast hot-spot reaction plus a slow reaction for the energy released by carbon clustering. A feature of the SURF model is that there is a partially decoupling between burn rate parameters and detonation wave properties. Previously, parameters for PBX 9502 that control shock ini- tiation had been calibrated to Pop plot data (distance-of-run to detonation as a function of shock pressure initiating the detonation). Here burn rate parameters for the high pres- sure regimemore » are adjusted to t the failure diameter and the limiting detonation speed just above the failure diameter. Simulated results are shown for an uncon ned rate stick when the 9502 diameter is slightly above and slightly below the failure diameter. Just above the failure diameter, in the rest frame of the detonation wave, the front is sonic at the PBX/air interface. As a consequence, the lead shock in the neighborhood of the interface is supported by the detonation pressure in the interior of the explosive rather than the reaction immediately behind the front. In the interior, the sonic point occurs near the end of the fast hot-spot reaction. Consequently, the slow carbon clustering reaction can not a ect the failure diameter. Below the failure diameter, the radial extent of the detonation front decreases starting from the PBX/air interface. That is, the failure starts at the PBX boundary and propagates inward to the axis of the rate stick.« less

An Abrupt Transition to an Intergranular Failure Mode in the Near-Threshold Fatigue Crack Growth Regime in Ni-Based Superalloys

NASA Astrophysics Data System (ADS)

Telesman, J.; Smith, T. M.; Gabb, T. P.; Ring, A. J.

2018-06-01

Cyclic near-threshold fatigue crack growth (FCG) behavior of two disk superalloys was evaluated and was shown to exhibit an unexpected sudden failure mode transition from a mostly transgranular failure mode at higher stress intensity factor ranges to an almost completely intergranular failure mode in the threshold regime. The change in failure modes was associated with a crossover of FCG resistance curves in which the conditions that produced higher FCG rates in the Paris regime resulted in lower FCG rates and increased ΔK th values in the threshold region. High-resolution scanning and transmission electron microscopy were used to carefully characterize the crack tips at these near-threshold conditions. Formation of stable Al-oxide followed by Cr-oxide and Ti-oxides was found to occur at the crack tip prior to formation of unstable oxides. To contrast with the threshold failure mode regime, a quantitative assessment of the role that the intergranular failure mode has on cyclic FCG behavior in the Paris regime was also performed. It was demonstrated that even a very limited intergranular failure content dominates the FCG response under mixed mode failure conditions.

Yield and failure criteria for composite materials under static and dynamic loading

DOE PAGES

Daniel, Isaac M.

2015-12-23

To facilitate and accelerate the process of introducing, evaluating and adopting of new material systems, it is important to develop/establish comprehensive and effective procedures of characterization, modeling and failure prediction of structural laminates based on the properties of the constituent materials, e. g., fibers, matrix, and the single ply or lamina. A new failure theory, the Northwestern (NU-Daniel) theory, has been proposed for predicting lamina yielding and failure under multi-axial states of stress including strain rate effects. It is primarily applicable to matrix-dominated interfiber/interlaminar failures. It is based on micromechanical failure mechanisms but is expressed in terms of easily measuredmore » macroscopic lamina stiffness and strength properties. It is presented in the form of a master failure envelope incorporating strain rate effects. The theory was further adapted and extended to the prediction of in situ first ply yielding and failure (FPY and FPF) and progressive failure of multi-directional laminates under static and dynamic loadings. The significance of this theory is that it allows for rapid screening of new composite materials without very extensive testing and offers easily implemented design tools.« less

The Effects of ELDRS at Ultra-Low Dose Rates

NASA Technical Reports Server (NTRS)

Chen, Dakai; Forney, James; Carts, Martin; Phan, Anthony; Pease, Ronald; Kruckmeyer, Kirby; Cox, Stephen; LaBel, Kenneth; Burns, Samuel; Albarian, Rafi;

Devil's Slide: An evolving feature of California's coastal landscape

NASA Astrophysics Data System (ADS)

Thomas, M.; Loague, K.

2013-12-01

Coastal landslides in the United States remain a persistent threat to human life and urban development. The focus of this study is a landslide-prone section of the central California coastline, approximately 20 km south of San Francisco, known as Devil's Slide. This investigation employs an extensive aerial image inventory, digital elevation models (DEMs), and a water balance / limit-equilibrium approach to better understand the spatial and temporal characteristics of deep-seated bedrock slides at the site. Photographic surveys of the area reveal nearly three kilometers of headscarp and a complex network of slope failures that respond to hydrologic, seismic, and anthropogenic perturbations. DEM analysis suggests that, for a 145-year period (1866 to 2010), the study area experienced an average coastal retreat rate of 0.14 m yr-1 and an average volumetric loss of 11,216 m3 yr-1. At least 38% of the landscape evolution in the steep coastal terrain has been driven by slope failure events. A loosely coupled water balance / limit-equilibrium analysis quantitatively illustrates the precarious nature of the active landslide zone at the site. The slope is shown to be unstable for a large suite of equally-likely scenarios. The analyses presented herein suggest that future work should include a rigorous characterization of pore-water pressure development, driven by comprehensive simulations of subsurface hydrologic response, to improve our understanding of slope failure initiation at the Devil's Slide site.

Experiences of air travel in patients with chronic heart failure

PubMed Central

Ingle, Lee; Hobkirk, James; Damy, Thibaud; Nabb, Samantha; Clark, Andrew L.; Cleland, John G.F.

2012-01-01

Aim To conduct a survey in a representative cohort of ambulatory patients with stable, well managed chronic heart failure (CHF) to discover their experiences of air travel. Methods An expert panel including a cardiologist, an exercise scientist, and a psychologist developed a series of survey questions designed to elicit CHF patients' experiences of air travel (Appendix 1). The survey questions, information sheets and consent forms were posted out in a self-addressed envelope to 1293 CHF patients. Results 464 patients (response rate 39%) completed the survey questionnaires. 54% of patients had travelled by air since their heart failure diagnosis. 20% of all patients reported difficulties acquiring travel insurance. 65% of patients who travelled by air experienced no health-related problems. 35% of patients who travelled by air experienced health problems, mainly at the final destination, going through security and on the aircraft. 27% of all patients would not travel by air in the future. 38% of patients would consider flying again if there were more leg room on the aeroplane, if their personal health improved (18%), if they could find cheaper travel insurance (19%), if there were less waiting at the airport (11%), or if there were less walking/fewer stairs to negotiate at the airport (7%). Conclusion For most patients in this sample of stable, well managed CHF, air travel was safe. PMID:21256607

Role of neuropeptide Y in renal sympathetic vasoconstriction: studies in normal and congestive heart failure rats.

PubMed

DiBona, G F; Sawin, L L

2001-08-01

Sympathetic nerve activity, including that in the kidney, is increased in heart failure with increased plasma concentrations of norepinephrine and the vasoconstrictor cotransmitter neuropeptide Y (NPY). We examined the contribution of NPY to sympathetically mediated alterations in kidney function in normal and heart failure rats. Heart failure rats were created by left coronary ligation and myocardial infarction. In anesthetized normal rats, the NPY Y(1) receptor antagonist, H 409/22, at two doses, had no effect on heart rate, arterial pressure, or renal hemodynamic and excretory function. In conscious severe heart failure rats, high-dose H 409/22 decreased mean arterial pressure by 8 +/- 2 mm Hg but had no effect in normal and mild heart failure rats. During graded frequency renal sympathetic nerve stimulation (0 to 10 Hz), high-dose H 409/22 attenuated the decreases in renal blood flow only at 10 Hz (-36% +/- 5%, P <.05) in normal rats but did so at both 4 (-29% +/- 4%, P <.05) and 10 Hz (-33% +/- 5%, P <.05) in heart failure rats. The glomerular filtration rate, urinary flow rate, and sodium excretion responses to renal sympathetic nerve stimulation were not affected by high-dose H 409/22 in either normal or heart failure rats. NPY does not participate in the regulation of kidney function and arterial pressure in normal conscious or anesthetized rats. When sympathetic nervous system activity is increased, as in heart failure and intense renal sympathetic nerve stimulation, respectively, a small contribution of NPY to maintenance of arterial pressure and to sympathetic renal vasoconstrictor responses may be identified.

Streambanks: A net source of sediment and phosphorus to streams and rivers.

PubMed

Fox, Garey A; Purvis, Rebecca A; Penn, Chad J

2016-10-01

Sediment and phosphorus (P) are two primary pollutants of surface waters. Many studies have investigated loadings from upland sources or even streambed sediment, but in many cases, limited to no data exist to determine sediment and P loading from streambanks on a watershed scale. The objectives of this paper are to review the current knowledge base on streambank erosion and failure mechanisms, streambank P concentrations, and streambanks as P loading sources and then also to identify future research needs on this topic. In many watersheds, long-term loading of soil and associated P to stream systems has created a source of eroded soil and P that may interact with streambank sediment and be deposited in floodplains downstream. In many cases streambanks were formed from previously eroded and deposited alluvial material and so the resulting soils possess unique physical and chemical properties from adjacent upland soils. Streambank sediment and P loading rates depend explicitly on the rate of streambank migration and the concentration of P stored within bank materials. From the survey of literature, previous studies report streambank total P concentrations that consistently exceeded 250 mg kg(-1) soil. Only a few studies also reported water soluble or extractable P concentrations. More research should be devoted to understanding the dynamic processes between different P pools (total P versus bioavailable P), and sorption or desorption processes under varying hydraulic and stream chemistry conditions. Furthermore, the literature reported that streambank erosion and failure and gully erosion were reported to account for 7-92% of the suspended sediment load within a channel and 6-93% of total P. However, significant uncertainty can occur in such estimates due to reach-scale variability in streambank migration rates and future estimates should consider the use of uncertainty analysis approaches. Research is also needed on the transport rates of dissolved and sediment-bound P through the entire stream system of a watershed to identify critical upland and/or near-stream conservation practices. Extensive monitoring of the impact of restoration/rehabilitation efforts on reducing sediment and P loading are limited. From an application standpoint, streambank P contributions to streams should be more explicitly accounted for in developing total maximum daily loads in watersheds. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Deceased donor liver transplantation].

PubMed

Seehofer, D; Schöning, W; Neuhaus, P

2013-05-01

Deceased donor liver transplantation is nowadays a routine procedure for the treatment of terminal liver failure and often represents the only chance of a cure. Under given optimal conditions excellent long-term results can be obtained with 15-year survival rates of well above 60 %.In Germany the outcome after liver transplantation has deteriorated since the introduction of an allocation policy, which is based on the medical urgency. At present 25 % of liver graft recipients die within the first year after transplantation. In contrast 1-year survival in most other countries, e.g. in the USA or the United Kingdom is around 90 % and therefore significantly better. Reasons for the inferior results in Germany are on the one hand an increasing number of critically ill recipients and on the other hand an unfavorable situation for organ donation. In comparison with other countries the organ donation rate is low and moreover the risk profile of these donors is above average. This combination of organ shortage and organ allocation represents a big challenge for the future orientation of liver transplantation and creates the potential for conflict. These cannot be solved on a medical basis but require a social consensus.Because of the present inferior results and because of the high expenses of the present system we suggest a discussion on future allocation policies as well as on future centre structures in Germany. In addition to the medical urgency the maximum benefit should also be considered for organ allocation.

17 CFR 12.35 - Consequences of a party's failure to comply with a discovery order.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Consequences of a party's failure to comply with a discovery order. 12.35 Section 12.35 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION RULES RELATING TO REPARATIONS Discovery § 12.35 Consequences of a party's...

Assessing the Causes of Encapsulant Delamination in PV Modules

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

Wohlgemuth, John H.; Hacke, Peter; Bosco, Nick

Delamination of the encapsulant is one of the most prevalent PV module field failures. This paper will present examples of various types of delaminations that have been observed in the field. It will then discuss the development of accelerated stress tests designed to duplicate those field failures and thus provide tools for avoiding them in the future.

Understanding the mechanical and acoustical characteristics of sand aggregates compacting under triaxial conditions

NASA Astrophysics Data System (ADS)

Hangx, Suzanne; Brantut, Nicolas

2016-04-01

Mechanisms such as grain rearrangement, coupled with elastic deformation, grain breakage, grain rearrangement, grain rotation, and intergranular sliding, play a key role in determining porosity and permeability reduction during burial of clastic sediments. Similarly, in poorly consolidated, highly porous sands and sandstones, grain rotation, intergranular sliding, grain failure, and pore collapse often lead to significant reduction in porosity through the development of compaction bands, with the reduced porosity and permeability of such bands producing natural barriers to flow within reservoir rocks. Such time-independent compaction processes operating in highly porous water- and hydrocarbon-bearing clastic reservoirs can exert important controls on production-related reservoir deformation, subsidence, and induced seismicity. We performed triaxial compression experiments on sand aggregates consisting of well-rounded Ottawa sand (d = 300-400 μm; φ = 36.1-36.4%) at room temperature, to systematically investigate the effect of confining pressure (Pceff = 5-100 MPa), strain rate (10-6-10-4 s-1) and chemical environment (decane vs. water; Pf = 5 MPa) on compaction. For a limited number of experiments grain size distribution (d = 180-500 μm) and grain shape (subangular Beaujean sand; d = 180-300 μm) were varied to study their effect. Acoustic emission statistics and location, combined with microstructural and grain size analysis, were used to verify the operating microphysical compaction mechanisms. All tests showed significant pre-compaction during the initial hydrostatic (set-up) phase, with quasi-elastic loading behaviour accompanied by permanent deformation during the differential loading stage. This permanent volumetric strain involved elastic grain contact distortion, particle rearrangement, and grain failure. From the acoustic data and grain size analysis, it was evident that at low confining pressure grain rearrangement controlled compaction, with grain failure being present but occurring to a relatively limited extent. Acoustic emission localization showed that failure was focussed along a broad shear plane. At higher confining pressure pervasive grain failure clearly accommodated compaction, though no strain localization was observed and failure appeared to be through cataclastic flow. Chemical environment, i.e. chemically inert decane vs. water as a pore fluid, had no significant effect on compaction in the strain rate range tested. Grain size distribution or grain shape also appeared to not affect the observed mechanical behaviour. Our results can be used to better understand the compaction behaviour of poorly consolidated sandstones. Future research will focus on understanding the effect of cementation on strain localization in deforming artificial Ottawa sandstone.

The past, present and future of renin–angiotensin aldosterone system inhibition☆

PubMed Central

Mentz, Robert J.; Bakris, George L.; Waeber, Bernard; McMurray, John J.V.; Gheorghiade, Mihai; Ruilope, Luis M.; Maggioni, Aldo P.; Swedberg, Karl; Piña, Ileana L.; Fiuzat, Mona; O’Connor, Christopher M.; Zannad, Faiez; Pitt, Bertram

2014-01-01

The renin–angiotensin aldosterone system (RAAS) is central to the pathogenesis of cardiovascular disease. RAAS inhibition can reduce blood pressure, prevent target organ damage in hypertension and diabetes, and improve outcomes in patients with heart failure and/or myocardial infarction. This review presents the history of RAAS inhibition including a summary of key heart failure, myocardial infarction, hypertension and atrial fibrillation trials. Recent developments in RAAS inhibition are discussed including implementation and optimization of current drug therapies. Finally, ongoing clinical trials, opportunities for future trials and issues related to the barriers and approvability of novel RAAS inhibitors are highlighted. PMID:23121914

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.

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

PubMed

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

2017-05-01

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

Large motion high cycle high speed optical fibers for space based applications.

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

Stromberg, Peter G.; Tandon, Rajan; Gibson, Cory S.

2014-10-01

Future remote sensing applications will require higher resolution and therefore higher data rates (up to perhaps 100 gigabits per second) while achieving lower mass and cost. A current limitation to the design space is high speed high bandwidth data does not cross movable gimbals because of cabling issues. This requires the detectors to be off gimbal. The ability to get data across the gimbal would open up efficiencies in designs where the detectors and the electronics can be placed anywhere on the system. Fiber optic cables provide light weight high speed high bandwidth connections. Current options are limited to 20,000more » cycles as opposed to the 1,000,000 cycles needed for future space based applications. To extend this to the million+ regime, requires a thorough understanding of the failure mechanisms and the materials, proper selection of materials (e.g., glass and jacket material) allowable geometry changes to the cable, radiation hardness, etc.« less

Success in School for Justice-Involved Girls: Do Specific Aspects of Developmental Immaturity Matter?

PubMed Central

Haney-Caron, Emily; Goldstein, Naomi E. S.; Giallella, Christy L.; Kemp, Kathleen; Romaine, Christina Riggs

2016-01-01

Developmental immaturity (DI) may help explain some of the variability in aspects of academic achievement among girls in the juvenile justice system, a population with high rates of truancy, dropout, and school failure. This study examined the relationships among the decision making and independent functioning components of DI, verbal intelligence, and academic achievement within this population. Using data from 60 girls in residential juvenile justice facilities, multiple regression analyses indicated that verbal IQ moderated the relationship between the DI construct of decision making and academic achievement. Self-reported school attendance and number of previous arrests did not significantly mediate the relationship between DI and academic achievement. These results may indicate that the decision-making factor of DI may be particularly important, and, if results are replicated, future intervention efforts could focus more on improving this skill within this juvenile justice population. Additionally, the overall importance of the full DI construct is an important area of future study. PMID:28082833

A maximum entropy fracture model for low and high strain-rate fracture in TinSilverCopper alloys

NASA Astrophysics Data System (ADS)

Chan, Dennis K.

SnAgCu solder alloys exhibit significant rate-dependent constitutive behavior. Solder joints made of these alloys exhibit failure modes that are also rate-dependent. Solder joints are an integral part of microelectronic packages and are subjected to a wide variety of loading conditions which range from thermo-mechanical fatigue to impact loading. Consequently, there is a need for non-empirical rate-dependent failure theory that is able to accurately predict fracture in these solder joints. In the present thesis, various failure models are first reviewed. But, these models are typically empirical or are not valid for solder joints due to limiting assumptions such as elastic behavior. Here, the development and validation of a maximum entropy fracture model (MEFM) valid for low strain-rate fracture in SnAgCu solders is presented. To this end, work on characterizing SnAgCu solder behavior at low strain-rates using a specially designed tester to estimate parameters for constitutive models is presented. Next, the maximum entropy fracture model is reviewed. This failure model uses a single damage accumulation parameter and relates the risk of fracture to accumulated inelastic dissipation. A methodology is presented to extract this model parameter through a custom-built microscale mechanical tester for Sn3.8Ag0.7Cu solder. This single parameter is used to numerically simulate fracture in two solder joints with entirely different geometries. The simulations are compared to experimentally observed fracture in these same packages. Following the simulations of fracture at low strain rate, the constitutive behavior of solder alloys across nine decades of strain rates through MTS compression tests and split-Hopkinson bar are presented. Preliminary work on using orthogonal machining as novel technique of material characterization at high strain rates is also presented. The resultant data from the MTS compression and split-Hopkinson bar tester is used to demonstrate the localization of stress to the interface of solder joints at high strain rates. The MEFM is further extended to predict failure in brittle materials. Such an extension allows for fracture prediction within intermetallic compounds (IMCs) in solder joints. It has been experimentally observed that the failure mode shifts from bulk solder to the IMC layer with increasing loading rates. The extension of the MEFM would allow for prediction of the fracture mode within the solder joint under different loading conditions. A fracture model capable of predicting failure modes at higher strain rates is necessary, as mobile electronics are becoming ubiquitous. Mobile devices are prone to being dropped which can induce loading rates within solder joints that are much larger than experienced under thermo-mechanical fatigue. A range of possible damage accumulation parameters for Cu6Sn 5 is determined for the MEFM. A value within the aforementioned range is used to demonstrate the increasing likelihood of IMC fracture in solder joints with larger loading rates. The thesis is concluded with remarks about ongoing work that include determining a more accurate damage accumulation parameter for Cu6Sn 5 IMC, and on using machining as a technique for extracting failure parameters for the MEFM.

Failure analysis and modeling of a multicomputer system. M.S. Thesis

NASA Technical Reports Server (NTRS)

Subramani, Sujatha Srinivasan

1990-01-01

This thesis describes the results of an extensive measurement-based analysis of real error data collected from a 7-machine DEC VaxCluster multicomputer system. In addition to evaluating basic system error and failure characteristics, we develop reward models to analyze the impact of failures and errors on the system. The results show that, although 98 percent of errors in the shared resources recover, they result in 48 percent of all system failures. The analysis of rewards shows that the expected reward rate for the VaxCluster decreases to 0.5 in 100 days for a 3 out of 7 model, which is well over a 100 times that for a 7-out-of-7 model. A comparison of the reward rates for a range of k-out-of-n models indicates that the maximum increase in reward rate (0.25) occurs in going from the 6-out-of-7 model to the 5-out-of-7 model. The analysis also shows that software errors have the lowest reward (0.2 vs. 0.91 for network errors). The large loss in reward rate for software errors is due to the fact that a large proportion (94 percent) of software errors lead to failure. In comparison, the high reward rate for network errors is due to fast recovery from a majority of these errors (median recovery duration is 0 seconds).

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.

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

Menikoff, Ralph

Previously the SURFplus reactive burn model was calibrated for the TATB based explosive PBX 9502. The calibration was based on fitting Pop plot data, the failure diameter and the limiting detonation speed, and curvature effect data for small curvature. The model failure diameter is determined utilizing 2-D simulations of an unconfined rate stick to find the minimum diameter for which a detonation wave propagates. Here we examine the effect of mesh resolution on an unconfined rate stick with a diameter (10mm) slightly greater than the measured failure diameter (8 to 9 mm).

[Prognostic factors related to non surgical treatment failure of splenic injuries in the abdominal blunt trauma].

PubMed

Carvalho, Fábio Henrique de; Romeiro, Paula Christina Marra; Collaço, Iwan Augusto; Baretta, Giorgio Alfredo Pedroso; Freitas, Alexandre Coutinho Teixeira de; Matias, Jorge Eduardo Fouto

2009-04-01

Identify prognostic factors related to treatment failure of blunt splenic injuries managed by non surgical treatment (NST). Fifty six adult patients submitted to NST were prospectively studied. The injuries were diagnosed by computed axial tomography scan and classified according to AAST (American Association for Surgery of Trauma) criteria. Patients were divided in success and failure groups. NST failure was defined as the need for laparotomy for any reason. NST failures (19.6%) were due to: abdominal pain (45.4%), hemodinamic instability (36.4%), splenic haematoma associated to a fall in hematocrit (9.1%) and splenic abscess (9.1%). There were no failures in grade I and II of the splenic injuries; failure rate was 17.5% in grade III and IV injuries grouped, and 80% in grade V injuries (p = 0,0008). In the success group, 31.3% patients received red cell transfusions, versus 63.6% patients in the failure group (p = 0,05). Failure rate in patients with ISS = 8 was zero; 15.9% in patients with ISS 9 to 25; and 50% in patients with ISS = 26 (p = 0,05). There were no deaths or missed bowel injuries. ISS and splenic injury grade were related to failure of NST.

The Reformulated Model of Learned Helplessness: An Empirical Test.

ERIC Educational Resources Information Center

Rothblum, Esther D.; Green, Leon

Abramson, Seligman and Teasdale's reformulated model of learned helplessness hypothesized that an attribution of causality intervenes between the perception of noncontingency and the future expectation of future noncontingency. To test this model, relationships between attribution and performance under failure, success, and control conditions were…

Sustainability - What are the Odds? Guessing the Future of our Environment, Economy, and Society

EPA Science Inventory

This article examines the concept of sustainability from a global perspective, describing how alternative futures might develop in the environmental, economic, and social dimensions. The alternatives to sustainability appear to be (a) a catastrophic failure of life support, econo...

Future directions in 980-nm pump lasers: submarine deployment to low-cost watt-class terrestrial pumps

NASA Astrophysics Data System (ADS)

Gulgazov, Vadim N.; Jackson, Gordon S.; Lascola, Kevin M.; Major, Jo S.; Parke, Ross; Richard, Tim; Rossin, Victor V.; Zhang, Kai

1999-09-01

The demands of global bandwidth and distribution are rising rapidly as Internet usage grows. This fundamentally means that more photons are flowing within optical cables. While transmitting sources launches some optical power, the majority of the optical power that is present within modern telecommunication systems originates from optical amplifiers. In addition, modern optical amplifiers offer flat optical gain over broad wavelength bands, thus making possible dense wavelength de-multiplexing (DWDM) systems. Optical amplifier performance, and by extension the performance of the laser pumps that drive them, is central to the future growth of both optical transmission and distribution systems. Erbium-doped amplifiers currently dominate optical amplifier usage. These amplifiers absorb pump light at 980 nm and/or 1480 nm, and achieve gain at wavelengths around 1550 nm. 980 nm pumps achieve better noise figures and are therefore used for the amplification of small signals. Due to the quantum defect, 1480 nm lasers deliver more signal photon per incident photon. In addition, 1480 nm lasers are less expensive than 980 nm lasers. Thus, 1480 nm pump lasers are used for amplification in situations where noise is not critical. The combination of these traits leads to the situation where many amplifiers contain 980 nm lasers to pump the input section of the Er- doped fiber with 1480 nm lasers being used to pump the latter section of Er fiber. This can be thought of as using 980 nm lasers to power an optical pre-amplifier with the power amplification function being pump with 1480 nm radiation. This paper will focus on 980 nm pump lasers and the impact that advances in 980 nm pump technology will have on optical amplification systems. Currently, 980 nm technology is rapidly advancing in two areas, power and reliability. Improving reliability is becoming increasingly important as amplifiers move towards employing more pump lasers and using these pump lasers without redundancy. Since the failure rate allowable for an amplifier is not a function of the number of pumps employed in the amplifier, the allowable failure rate of an individual pump laser is decreasing for next-generation amplifiers. This will lead to specifications for terrestrial pumps well below 1000 FIT, and may lead to the case where high power amplifiers need laser pump reliability to approach 100 FIT. In addition, 980 nm laser diodes are now being deployed in submarine systems where failure rates lower than 100 FIT are commonly specified. It is obvious that both terrestrial and submarine markets are pushing allowable failure rates for pumps for optical amplifiers to continually decrease. A second push for improvement is in the output power of 980 nm pump modules. There exist a number of motivations for increasing the output power of pump lasers. First, each additional channel in a DWDM system requires additional power. To first order, a doubling in channel count implies a doubling in pump power. Second, larger amplifiers require multiple pumps. Higher output power from pump modules allows for fewer pumps, less complicated control systems and smaller size amplifiers. The discussion of this paper will focus on how current development progress of 980 nm laser diodes addresses these issues: better reliability and higher output powers.

Risk factors for early failure after peripheral endovascular intervention: application of a reliability engineering approach.

PubMed

Meltzer, Andrew J; Graham, Ashley; Connolly, Peter H; Karwowski, John K; Bush, Harry L; Frazier, Peter I; Schneider, Darren B

2013-01-01

We apply an innovative and novel analytic approach, based on reliability engineering (RE) principles frequently used to characterize the behavior of manufactured products, to examine outcomes after peripheral endovascular intervention. We hypothesized that this would allow for improved prediction of outcome after peripheral endovascular intervention, specifically with regard to identification of risk factors for early failure. Patients undergoing infrainguinal endovascular intervention for chronic lower-extremity ischemia from 2005 to 2010 were identified in a prospectively maintained database. The primary outcome of failure was defined as patency loss detected by duplex ultrasonography, with or without clinical failure. Analysis included univariate and multivariate Cox regression models, as well as RE-based analysis including product life-cycle models and Weibull failure plots. Early failures were distinguished using the RE principle of "basic rating life," and multivariate models identified independent risk factors for early failure. From 2005 to 2010, 434 primary endovascular peripheral interventions were performed for claudication (51.8%), rest pain (16.8%), or tissue loss (31.3%). Fifty-five percent of patients were aged ≥75 years; 57% were men. Failure was noted after 159 (36.6%) interventions during a mean follow-up of 18 months (range, 0-71 months). Using multivariate (Cox) regression analysis, rest pain and tissue loss were independent predictors of patency loss, with hazard ratios of 2.5 (95% confidence interval, 1.6-4.1; P < 0.001) and 3.2 (95% confidence interval, 2.0-5.2, P < 0.001), respectively. The distribution of failure times for both claudication and critical limb ischemia fit distinct Weibull plots, with different characteristics: interventions for claudication demonstrated an increasing failure rate (β = 1.22, θ = 13.46, mean time to failure = 12.603 months, index of fit = 0.99037, R(2) = 0.98084), whereas interventions for critical limb ischemia demonstrated a decreasing failure rate, suggesting the predominance of early failures (β = 0.7395, θ = 6.8, mean time to failure = 8.2, index of fit = 0.99391, R(2) = 0.98786). By 3.1 months, 10% of interventions failed. This point (90% reliability) was identified as the basic rating life. Using multivariate analysis of failure data, independent predictors of early failure (before 3.1 months) included tissue loss, long lesion length, chronic total occlusions, heart failure, and end-stage renal disease. Application of a RE framework to the assessment of clinical outcomes after peripheral interventions is feasible, and potentially more informative than traditional techniques. Conceptualization of interventions as "products" permits application of product life-cycle models that allow for empiric definition of "early failure" may facilitate comparative effectiveness analysis and enable the development of individualized surveillance programs after endovascular interventions. Copyright © 2013 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.

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

Zhang, Chao; Xu, Jun; Cao, Lei

The electrodes of lithium-ion batteries (LIB) are known to be brittle and to fail earlier than the separators during an external crush event. Thus, the understanding of mechanical failure mechanism for LIB electrodes (anode and cathode) is critical for the safety design of LIB cells. In this paper, we present experimental and numerical studies on the constitutive behavior and progression of failure in LIB electrodes. Mechanical tests were designed and conducted to evaluate the constitutive properties of porous electrodes. Constitutive models were developed to describe the stress-strain response of electrodes under uniaxial tensile and compressive loads. The failure criterion andmore » a damage model were introduced to model their unique tensile and compressive failure behavior. The failure mechanism of LIB electrodes was studied using the blunt rod test on dry electrodes, and numerical models were built to simulate progressive failure. The different failure processes were examined and analyzed in detail numerically, and correlated with experimentally observed failure phenomena. Finally, the test results and models improve our understanding of failure behavior in LIB electrodes, and provide constructive insights on future development of physics-based safety design tools for battery structures under mechanical abuse.« less

Researchers at NREL Find Fewer Failures of PV Panels and Different

Science.gov Websites

10, 2017 Overall failure rates for photovoltaic (PV) solar panels have fallen dramatically when Failures of PV Panels and Different Degradation Modes in Systems Installed after 2000 Researchers at NREL Find Fewer Failures of PV Panels and Different Degradation Modes in Systems Installed after 2000 April

Nonoperating Failure Rates for Avionics Study.

DTIC Science & Technology

1980-04-01

Missile, 1 August 1973. Temperature Readings at Three Indicated Locations ............................ 3-10 3-7 Operating vs . Nonoperating Failure...Failures vs . Mission Duration for Jet Aircraft Equipment ... ...................... ... 4-39 4-17 Cumulative Total Failures vs . Mission Duration for Jet...AVIONIC EQUIPMENT FIELD CHARACTERISTICS To better understand the type of service exposure avionic equipment must withstand , several aspects of the

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

Kashiwa, Bryan Andrew; Hull, Lawrence Mark

Highlights of recent phenomenological studies of metal failure are given. Failure leading to spallation and fragmentation are typically of interest. The current ‘best model’ includes the following; a full history stress in tension; nucleation initiating dynamic relaxation; toward a tensile yield function; failure dependent on strain, strain rate, and temperature; a mean-preserving ‘macrodefect’ is introduced when failure occurs in tension; and multifield theoretical refinements

Reliability Prediction Models for Discrete Semiconductor Devices

DTIC Science & Technology

1988-07-01

influence failure rate were device construction, semiconductor material, junction temperature, electrical stress, circuit application., a plication...found to influence failure rate were device construction, semiconductor material, junction temperature, electrical stress, circuit application...MFA Airbreathlng 14issile, Flight MFF Missile, Free Flight ML Missile, Launch MMIC Monolithic Microwave Integrated Circuits MOS Metal-Oxide

The BGR Contingency Model for Leading Change

ERIC Educational Resources Information Center

Brown, Derek R.; Gordon, Raymond; Rose, Dennis Michael

2012-01-01

The continuing failure rates of change initiatives, combined with an increasingly complex business environment, have created significant challenges for the practice of change management. High failure rates suggest that existing change models are not working, or are being incorrectly used. A different mindset to change is required. The BGR…

38 CFR 4.97 - Schedule of ratings-respiratory system.

Code of Federal Regulations, 2013 CFR

2013-07-01

... pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension (shown by... hypertension (shown by Echo or cardiac catheterization), or; episode(s) of acute respiratory failure, or...; cor pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension...

38 CFR 4.97 - Schedule of ratings-respiratory system.

Code of Federal Regulations, 2012 CFR

2012-07-01

... pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension (shown by... hypertension (shown by Echo or cardiac catheterization), or; episode(s) of acute respiratory failure, or...; cor pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension...

38 CFR 4.97 - Schedule of ratings-respiratory system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension (shown by... hypertension (shown by Echo or cardiac catheterization), or; episode(s) of acute respiratory failure, or...; cor pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension...

38 CFR 4.97 - Schedule of ratings-respiratory system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension (shown by... hypertension (shown by Echo or cardiac catheterization), or; episode(s) of acute respiratory failure, or...; cor pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension...

38 CFR 4.97 - Schedule of ratings-respiratory system.

Code of Federal Regulations, 2014 CFR

2014-07-01

... pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension (shown by... hypertension (shown by Echo or cardiac catheterization), or; episode(s) of acute respiratory failure, or...; cor pulmonale (right heart failure), or; right ventricular hypertrophy, or; pulmonary hypertension...

A review of the success and failure characteristics of resin-bonded bridges.

PubMed

Miettinen, M; Millar, B J

2013-07-01

This literature review was designed to assess and compare the success rates and modes of failure of metal-framed, fibre-reinforced composite and all-ceramic resin-bonded bridges. A Medline search (Ovid), supplemented by hand searching, was conducted to identify prospective and retrospective cohort studies on different resin-bonded bridges within the last 16 years. A total of 49 studies met the pre-set inclusion criteria. Success rates of 25 studies on metal-framed, 17 studies on fibre-reinforced composite and 7 studies on all-ceramic resin-bonded bridges were analysed and characteristics of failures were identified. The analysis of the studies indicated an estimation of annual failure rates per year to be 4.6% (±1.3%, 95% CI) for metal-framed, 4.1% (±2.1%, 95% CI) for fibre-reinforced and 11.7% (±1.8%, 95% CI) for all-ceramic resin-bonded bridges. The most frequent complications were: debonding for metal-framed, resin-bonded bridges (93% of all failures); delamination of the composite veneering material for the fibre-reinforced bridges (41%) and fracture of the framework for the all-ceramic bridges (57%). All types of resin-bonded bridges provide an effective short- to medium-term option, with all-ceramic performing least well and having the least favourable mode of failure. The methods of failures were different for different bridges with metal frameworks performing the best over time.

Clinical heterogeneity in autoimmune acute liver failure

PubMed Central

Chavez-Tapia, Norberto C; Martinez-Salgado, Julio; Granados, Julio; Uribe, Misael; Tellez-Avila, Felix I

2007-01-01

AIM: To describe the outcome and prognosis in a cohort of patients with acute liver failure due to autoimmune hepatitis without liver transplantation. METHODS: A retrospective trial was conducted in 11 patients with acute liver failure due to autoimmune hepatitis who attended the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubiran. Demographic, biochemical and severity indexes, and treatment and outcome were assessed. RESULTS: Among the 11 patients, with a median age of 31 years, 72% had inflammatory response syndrome, and six patients received corticosteroids. The mortality rate within four weeks was 56%, and the one-year survival was 27%. In the survivors, severity indexes were lower and 83% received corticosteroids. CONCLUSION: We observed a relatively high survival rate in patients with acute liver failure due to autoimmune hepatitis. This survival rate could be influenced by severity of the disease and/or use of corticosteroids. PMID:17465474

[Heart failure mortality in Spain: is there an andalusian paradox?].

PubMed

Jiménez-Navarro, M; Gómez-Doblas, J; Molero, E; Galván, E de Teresa

2006-06-01

Congestive heart failure has a high mortality, as reflected in different clinical trials and observational studies. Spain, as other countries around the Mediterranean basin, have a relatively low rate of coronary deaths, attributed to the so-called Mediterranean lifestyle. Andalusia, in the southern most part of Spain, constitutes the paradigm of Mediterranean lifestyle. However, different reports show that the prevalence of ischemic heart disease is higher in Andalusia than in other zones of Spain. Thus the mortality rate due to heart failure in Spain in the year 2000 per 100,000 inhabitants was 27.3 in men and 28.88 in women and each one of the eight Andalusia provinces had greater rates than the national mean in both men and woman. Even in countries with a relatively low prevalence of coronary heart disease as is the case in Spain, heart failure mortality seems to be parallel to local differences in IHD prevalence.

Explosive Model Tarantula 4d/JWL++ Calibration of LX-17

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

Souers, P C; Vitello, P A

2008-09-30

Tarantula is an explosive kinetic package intended to do detonation, shock initiation, failure, corner-turning with dead zones, gap tests and air gaps in reactive flow hydrocode models. The first, 2007-2008 version with monotonic Q is here run inside JWL++ with square zoning from 40 to 200 zones/cm on ambient LX-17. The model splits the rate behavior in every zone into sections set by the hydrocode pressure, P + Q. As the pressure rises, we pass through the no-reaction, initiation, ramp-up/failure and detonation sections sequentially. We find that the initiation and pure detonation rate constants are largely insensitive to zoning butmore » that the ramp-up/failure rate constant is extremely sensitive. At no time does the model pass every test, but the pressure-based approach generally works. The best values for the ramp/failure region are listed here in Mb units.« less

Six-minute walk test and heart rate variability: lack of association in advanced stages of heart failure.

PubMed

Woo, M A; Moser, D K; Stevenson, L W; Stevenson, W G

1997-09-01

The 6-minute walk and heart rate variability have been used to assess mortality risk in patients with heart failure, but their relationship to each other and their usefulness for predicting mortality at 1 year are unknown. To assess the relationships between the 6-minute walk test, heart rate variability, and 1-year mortality. A sample of 113 patients in advanced stages of heart failure (New York Heart Association Functional Class III-IV, left ventricular ejection < 0.25) were studied. All 6-minute walks took place in an enclosed, level, measured corridor and were supervised by the same nurse. Heart rate variability was measured by using (1) a standard-deviation method and (2) Poincaré plots. Data on RR intervals obtained by using 24-hour Holter monitoring were analyzed. Survival was determined at 1 year after the Holter recording. The results showed no significant associations between the results of the 6-minute walk and the two measures of heart rate variability. The results of the walk were related to 1-year mortality but not to the risk of sudden death. Both measures of heart rate variability had significant associations with 1-year mortality and with sudden death. However, only heart rate variability measured by using Poincaré plots was a predictor of total mortality and risk of sudden death, independent of left ventricular ejection fraction, serum levels of sodium, results of the 6-minute walk test, and the standard-deviation measure of heart rate variability. Results of the 6-minute walk have poor association with mortality and the two measures of heart rate variability in patients with advanced-stage heart failure and a low ejection fraction. Further studies are needed to determine the optimal clinical usefulness of the 6-minute walk and heart rate variability in patients with advanced-stage heart failure.

Clinical Adoption of Prognostic Biomarkers The Case for Heart Failure

PubMed Central

Kalogeropoulos, Andreas P.; Georgiopoulou, Vasiliki V.; Butler, Javed

2013-01-01

The recent explosion of scientific knowledge and technological progress has led to the discovery of a large array of circulating molecules commonly referred to as biomarkers. Biomarkers in heart failure research have been used to provide pathophysiological insights, aid in establishing the diagnosis, refine prognosis, guide management, and target treatment. However, beyond diagnostic applications of natriuretic peptides, there are currently few widely recognized applications for biomarkers in heart failure. This represents a remarkable discordance considering the number of molecules that have been shown to correlate with outcomes, refine risk prediction, or track disease severity in heart failure in the past decade. In this article, we use a broad framework proposed for cardiovascular risk markers to summarize the current state of biomarker development for heart failure patients. We utilize this framework to identify the challenges of biomarker adoption for risk prediction, disease management, and treatment selection for heart failure and suggest considerations for future research. PMID:22824105

Predicting subsequent task performance from goal motivation and goal failure.

PubMed

Healy, Laura C; Ntoumanis, Nikos; Stewart, Brandon D; Duda, Joan L

2015-01-01

Recent research has demonstrated that the cognitive processes associated with goal pursuit can continue to interfere with unrelated tasks when a goal is unfulfilled. Drawing from the self-regulation and goal-striving literatures, the present study explored the impact of goal failure on subsequent cognitive and physical task performance. Furthermore, we examined if the autonomous or controlled motivation underpinning goal striving moderates the responses to goal failure. Athletes (75 male, 59 female, Mage = 19.90 years, SDage = 3.50) completed a cycling trial with the goal of covering a given distance in 8 min. Prior to the trial, their motivation was primed using a video. During the trial they were provided with manipulated performance feedback, thus creating conditions of goal success or failure. No differences emerged in the responses to goal failure between the primed motivation or performance feedback conditions. We make recommendations for future research into how individuals can deal with failure in goal striving.

Investigation into Cause of High Temperature Failure of Boiler Superheater Tube

NASA Astrophysics Data System (ADS)

Ghosh, D.; Ray, S.; Roy, H.; Shukla, A. K.

2015-04-01

The failure of the boiler tubes occur due to various reasons like creep, fatigue, corrosion and erosion. This paper highlights a case study of typical premature failure of a final superheater tube of 210 MW thermal power plant boiler. Visual examination, dimensional measurement, chemical analysis, oxide scale thickness measurement, microstructural examination are conducted as part of the investigations. Apart from these investigations, sulfur print, Energy Dispersive spectroscopy (EDS) and X ray diffraction analysis (XRD) are also conducted to ascertain the probable cause of failure of final super heater tube. Finally it has been concluded that the premature failure of the super heater tube can be attributed to the combination of localized high tube metal temperature and loss of metal from the outer surface due to high temperature corrosion. The corrective actions have also been suggested to avoid this type of failure in near future.

Failure analysis of aluminum alloy components

NASA Technical Reports Server (NTRS)

Johari, O.; Corvin, I.; Staschke, J.

1973-01-01

Analysis of six service failures in aluminum alloy components which failed in aerospace applications is reported. Identification of fracture surface features from fatigue and overload modes was straightforward, though the specimens were not always in a clean, smear-free condition most suitable for failure analysis. The presence of corrosion products and of chemically attacked or mechanically rubbed areas here hindered precise determination of the cause of crack initiation, which was then indirectly inferred from the scanning electron fractography results. In five failures the crack propagation was by fatigue, though in each case the fatigue crack initiated from a different cause. Some of these causes could be eliminated in future components by better process control. In one failure, the cause was determined to be impact during a crash; the features of impact fracture were distinguished from overload fractures by direct comparisons of the received specimens with laboratory-generated failures.

Probabilistic safety analysis of earth retaining structures during earthquakes

NASA Astrophysics Data System (ADS)

Grivas, D. A.; Souflis, C.

1982-07-01

A procedure is presented for determining the probability of failure of Earth retaining structures under static or seismic conditions. Four possible modes of failure (overturning, base sliding, bearing capacity, and overall sliding) are examined and their combined effect is evaluated with the aid of combinatorial analysis. The probability of failure is shown to be a more adequate measure of safety than the customary factor of safety. As Earth retaining structures may fail in four distinct modes, a system analysis can provide a single estimate for the possibility of failure. A Bayesian formulation of the safety retaining walls is found to provide an improved measure for the predicted probability of failure under seismic loading. The presented Bayesian analysis can account for the damage incurred to a retaining wall during an earthquake to provide an improved estimate for its probability of failure during future seismic events.

Quality of care and investment in property, plant, and equipment in hospitals.

PubMed Central

Levitt, S W

1994-01-01

OBJECTIVE. This study explores the relationship between quality of care and investment in property, plant, and equipment (PPE) in hospitals. DATA SOURCES. Hospitals' investment in PPE was derived from audited financial statements for the fiscal years 1984-1989. Peer Review Organization (PRO) Generic Quality Screen (GQS) reviews and confirmed failures between April 1989 and September 1990 were obtained from the Massachusetts PRO. STUDY DESIGN. Weighted least squares regression models used PRO GQS confirmed failure rates as the dependent variable, and investment in PPE as the key explanatory variable. DATA EXTRACTION. Investment in PPE was standardized, summed by the hospital over the six years, and divided by the hospital's average number of beds in that period. The number of PRO reviewed cases with one or more GQS confirmed failures was divided by the total number of cases reviewed to create confirmed failure rates. PRINCIPAL FINDINGS. Investment in PPE in Massachusetts hospitals is correlated with GQS confirmed failure rates. CONCLUSIONS. A financial variable, investment in PPE, predicts certain dimensions of quality of care in hospitals. PMID:8113054

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.

Testing of Streckeisen STS-5A and Nanometrics Trillium 120PH Sensors for the Alaska Transportable Array

NASA Astrophysics Data System (ADS)

Abbasi Baghbadorani, A.; Aderhold, K.; Bloomquist, D.; Frassetto, A.; Miller, P. E.; Busby, R. W.

2017-12-01

Starting in 2014, the IRIS Transportable Array facility began to install and operate seismic stations in Alaska and western Canada. By the end of the project, the full deployment of the array will cover a grid of 280 stations spaced about 85 km apart covering all of mainland Alaska and parts of the Yukon, British Columbia, and the Northwest Territories. Approximately 200 stations will be operated directly by IRIS through at least 2019. A key aspect of the Alaska TA is the need for stations to operate autonomously, on account of the high cost of installation and potential subsequent visits to remote field-sites to repair equipment. The TA is using newly developed broadband seismometers Streckeisen STS-5A and Nanometrics Trillium-120PH, designed for installation in shallow posthole emplacements. These new instruments were extensively vetted beforehand, but they are still relatively new to the TA inventory. Here we will assess their performance under deployment conditions and after repeated commercial shipping and travel to the field. Our objective is to provide a thorough accounting of the identified failures of the existing inventory of posthole instruments. We will assess the practices and results of instrument testing by the PASSCAL Instrument Center/Array Operations Facility (PIC/AOF), Alaska Operations Center (AOC), and broadband seismic sensor manufacturers (Streckeisen, Nanometrics) in order to document potential factors in and stages during the process for instrument failures. This will help to quantify the overall reliability of the TA seismic sensors and quality of TA practices and data collection, and identify potential considerations in future TA operations. Our results show that the overall rate of failure of all posthole instruments is <4% out of 260. This is lower than the rates seen for vault sensor failures in the operation of the Lower 48 Transportable Array. For telemetered stations such as these installed in the TA Alaska array, we also show that noise analyses can capture a failed emplaced sensor and reveal improved station performance after sensor replacement, and that these are key elements in assessing whether or not a sensor should be replaced in the field.

Hospital Variation in Utilization of Life-Sustaining Treatments among Patients with Do Not Resuscitate Orders.

PubMed

Walkey, Allan J; Weinberg, Janice; Wiener, Renda Soylemez; Cooke, Colin R; Lindenauer, Peter K

2018-06-01

To determine between-hospital variation in interventions provided to patients with do not resuscitate (DNR) orders. United States Agency of Healthcare Research and Quality, Healthcare Cost and Utilization Project, California State Inpatient Database. Retrospective cohort study including hospitalized patients aged 40 and older with potential indications for invasive treatments: in-hospital cardiac arrest (indication for CPR), acute respiratory failure (mechanical ventilation), acute renal failure (hemodialysis), septic shock (central venous catheterization), and palliative care. Hierarchical logistic regression to determine associations of hospital "early" DNR rates (DNR order placed within 24 hours of admission) with utilization of invasive interventions. California State Inpatient Database, year 2011. Patients with DNR orders at high-DNR-rate hospitals were less likely to receive invasive mechanical ventilation for acute respiratory failure or hemodialysis for acute renal failure, but more likely to receive palliative care than DNR patients at low-DNR-rate hospitals. Patients without DNR orders experienced similar rates of invasive interventions regardless of hospital DNR rates. Hospitals vary widely in the scope of invasive or organ-supporting treatments provided to patients with DNR orders. © Health Research and Educational Trust.

Specificity rates for non-clinical, bilingual, Mexican Americans on three popular performance validity measures.

PubMed

Gasquoine, Philip G; Weimer, Amy A; Amador, Arnoldo

2017-04-01

To measure specificity as failure rates for non-clinical, bilingual, Mexican Americans on three popular performance validity measures: (a) the language format Reliable Digit Span; (b) visual-perceptual format Test of Memory Malingering; and (c) visual-perceptual format Dot Counting, using optimal/suboptimal effort cut scores developed for monolingual, English-speakers. Participants were 61 consecutive referrals, aged between 18 and 65 years, with <16 years of education who were subjectively bilingual (confirmed via formal assessment) and chose the language of assessment, Spanish or English, for the performance validity tests. Failure rates were 38% for Reliable Digit Span, 3% for the Test of Memory Malingering, and 7% for Dot Counting. For Reliable Digit Span, the failure rates for Spanish (46%) and English (31%) languages of administration did not differ significantly. Optimal/suboptimal effort cut scores derived for monolingual English-speakers can be used with Spanish/English bilinguals when using the visual-perceptual format Test of Memory Malingering and Dot Counting. The high failure rate for Reliable Digit Span suggests it should not be used as a performance validity measure with Spanish/English bilinguals, irrespective of the language of test administration, Spanish or English.

Rainfall-induced slope failures near Los Angeles detected by time series of high-resolution satellite imagery

NASA Astrophysics Data System (ADS)

McKinney, E.; Moon, S.

2017-12-01

Tectonically active, soil mantled, and often fire-scorched landscapes of the Los Angeles region are susceptible to slope failures, such as mudflow and landslides, during high-intensity precipitation events. During 2016-2017, this area received a precipitation rate that was 90 mm higher than the long-term precipitation rates averaged over 30 years. These precipitation rates were 24 % higher than the long-term averages and 245 % higher than those over the 2011-2016 period of drought. In this study, we examined the occurrences of slopes failures near Los Angeles in response to high rainfall rates over 2016-2017. We composited time series of high-resolution Planetscope satellite images with resolutions of 3 - 4 m/pixel for 4 selected locations after reviewing 190,000 km2 area in total. We mapped the surface changes by comparing satellite images before and after the winter 2016-2017. Preliminary analysis using spectral bands highlighted the surface changes made by mudflows, landslides, lake levels and land developments. We compared these changes across 2016-2017 with those over a period of recent drought (2011-2016) to assess the influence of high rainfall rates on slope failures.

Declining Risk of Sudden Death in Heart Failure.

PubMed

Shen, Li; Jhund, Pardeep S; Petrie, Mark C; Claggett, Brian L; Barlera, Simona; Cleland, John G F; Dargie, Henry J; Granger, Christopher B; Kjekshus, John; Køber, Lars; Latini, Roberto; Maggioni, Aldo P; Packer, Milton; Pitt, Bertram; Solomon, Scott D; Swedberg, Karl; Tavazzi, Luigi; Wikstrand, John; Zannad, Faiez; Zile, Michael R; McMurray, John J V

2017-07-06

The risk of sudden death has changed over time among patients with symptomatic heart failure and reduced ejection fraction with the sequential introduction of medications including angiotensin-converting-enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, and mineralocorticoid-receptor antagonists. We sought to examine this trend in detail. We analyzed data from 40,195 patients who had heart failure with reduced ejection fraction and were enrolled in any of 12 clinical trials spanning the period from 1995 through 2014. Patients who had an implantable cardioverter-defibrillator at the time of trial enrollment were excluded. Weighted multivariable regression was used to examine trends in rates of sudden death over time. Adjusted hazard ratios for sudden death in each trial group were calculated with the use of Cox regression models. The cumulative incidence rates of sudden death were assessed at different time points after randomization and according to the length of time between the diagnosis of heart failure and randomization. Sudden death was reported in 3583 patients. Such patients were older and were more often male, with an ischemic cause of heart failure and worse cardiac function, than those in whom sudden death did not occur. There was a 44% decline in the rate of sudden death across the trials (P=0.03). The cumulative incidence of sudden death at 90 days after randomization was 2.4% in the earliest trial and 1.0% in the most recent trial. The rate of sudden death was not higher among patients with a recent diagnosis of heart failure than among those with a longer-standing diagnosis. Rates of sudden death declined substantially over time among ambulatory patients with heart failure with reduced ejection fraction who were enrolled in clinical trials, a finding that is consistent with a cumulative benefit of evidence-based medications on this cause of death. (Funded by the China Scholarship Council and the University of Glasgow.).

The Remote Detection of Incipient Catastrophic Failure in Large Landslides

NASA Astrophysics Data System (ADS)

Petley, D.; Bulmer, M. H.; Murphy, W.; Mantovani, F.

2001-12-01

Landslide movement is commonly associated with brittle failure and ductile deformation. Kilburn and Petley (2001) proposed that cracking in landslides occurs due to downslope stress acting on the deforming horizon. If the assumption that a given crack event breaks a fixed distance of unbroken rock or soil the rate of cracking becomes equivalent to the number of crack events per unit time. Where crack growth (not nucleation) is occurring, the inverse rate of displacement changes linearly with time. Failure can be assumed to be the time at which displacement rates become infinitely large. Thus, for a slope heading towards catastrophic failure due to the development of a failure plane, this relationship would be linear, with the point at which failure will occur being the time when the line intercepts the x-axis. Increasing rates of deformation associated with ductile processes of crack nucleation would yield a curve with a negative gradient asymptopic to the x-axis. This hypothesis is being examined. In the 1960 movement of the Vaiont slide, Italy, although the rate of movement was accelerating, the plot of 1/deformation against time shows that it was increasing towards a steady state deformation. This movement has been associated with a low accumulated strain ductile phase of movement. In the 1963 movement event, the trend is linear. This was associated with a brittle phase of movement. A plot of 1/deformation against time for movement of the debris flow portion of the Tessina landslide (1998) shows a curve with a negative gradient asymptopic to the x-axis. This indicates that the debris flow moved as a result of ductile deformation processes. Plots of movement data for the Black Ven landslide over 1999 and 2001 also show curves that correlate with known deformation and catastrophic phases. The model results suggest there is a definable deformation pattern that is diagnostic of landslides approaching catastrophic failure. This pattern can be differentiated from landslides that are undergoing ductile deformation and those that are suffering crack nucleation.

Estimation of lifetime distributions on 1550-nm DFB laser diodes using Monte-Carlo statistic computations

NASA Astrophysics Data System (ADS)

Deshayes, Yannick; Verdier, Frederic; Bechou, Laurent; Tregon, Bernard; Danto, Yves; Laffitte, Dominique; Goudard, Jean Luc

2004-09-01

High performance and high reliability are two of the most important goals driving the penetration of optical transmission into telecommunication systems ranging from 880 nm to 1550 nm. Lifetime prediction defined as the time at which a parameter reaches its maximum acceptable shirt still stays the main result in terms of reliability estimation for a technology. For optoelectronic emissive components, selection tests and life testing are specifically used for reliability evaluation according to Telcordia GR-468 CORE requirements. This approach is based on extrapolation of degradation laws, based on physics of failure and electrical or optical parameters, allowing both strong test time reduction and long-term reliability prediction. Unfortunately, in the case of mature technology, there is a growing complexity to calculate average lifetime and failure rates (FITs) using ageing tests in particular due to extremely low failure rates. For present laser diode technologies, time to failure tend to be 106 hours aged under typical conditions (Popt=10 mW and T=80°C). These ageing tests must be performed on more than 100 components aged during 10000 hours mixing different temperatures and drive current conditions conducting to acceleration factors above 300-400. These conditions are high-cost, time consuming and cannot give a complete distribution of times to failure. A new approach consists in use statistic computations to extrapolate lifetime distribution and failure rates in operating conditions from physical parameters of experimental degradation laws. In this paper, Distributed Feedback single mode laser diodes (DFB-LD) used for 1550 nm telecommunication network working at 2.5 Gbit/s transfer rate are studied. Electrical and optical parameters have been measured before and after ageing tests, performed at constant current, according to Telcordia GR-468 requirements. Cumulative failure rates and lifetime distributions are computed using statistic calculations and equations of drift mechanisms versus time fitted from experimental measurements.

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

PubMed

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

2016-04-01

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

Ultrasound-guided axillary brachial plexus block versus local infiltration anesthesia for arteriovenous fistula creation at the forearm for hemodialysis in patients with chronic renal failure.

PubMed

Nofal, W H; El Fawal, S M; Shoukry, A A; Sabek, Eas; Malak, Wfa

2017-01-01

The primary failure rate for arteriovenous fistula (AVF) creation under local anesthesia for hemodialysis is about 30%. Axillary brachial plexus block (BPB) may improve blood flow through blood vessels used in fistula creation; it may improve the AVF blood flow and thus may reduce the primary failure rate after 3 months. Hundred and forty patients with chronic renal failure scheduled for AVF creation for hemodialysis were divided into two equal groups; Group 1 (AxBP-G) received ultrasound (US) guided axillary BPB, and Group 2 (LI-G) received local infiltration. We recorded the measurements of the brachial and radial arteries before and after anesthesia and the AVF blood flow in both groups at three different time points. Furthermore, the primary failure rate was recorded in each group and compared. After anesthesia, the mean radial artery blood flow in the AxBP-group was 3.52 ml/min more than the LI-group, and the brachial artery diameter was also 0.68 mm more than in the LI-group, both differences were statistically significant ( P < 0.05). There were significant increases ( P < 0.05) in the AVF blood flow in the AxBP-group more than the LI-group with mean differences of 29.6, 69.8, and 27.2 ml/min at 4 h, 1 week, and 3 months, respectively. The overall mean of AVF blood flow was 42.21 ml/min more in the AxBP group than the LI-group a difference which is statistically significant ( P < 0.001). The primary failure rate was 17% in the AxBP group versus 30% in the LI-group; however, this difference is not significant statistically ( P = 0.110). The US-guided axillary block increases AVF blood flow significantly more than local infiltration and nonsignificantly decreases the primary failure rate of the AVF after 3 months.

Constitutive behavior and progressive mechanical failure of electrodes in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Chao; Xu, Jun; Cao, Lei; Wu, Zenan; Santhanagopalan, Shriram

2017-07-01

The electrodes of lithium-ion batteries (LIB) are known to be brittle and to fail earlier than the separators during an external crush event. Thus, the understanding of mechanical failure mechanism for LIB electrodes (anode and cathode) is critical for the safety design of LIB cells. In this paper, we present experimental and numerical studies on the constitutive behavior and progression of failure in LIB electrodes. Mechanical tests were designed and conducted to evaluate the constitutive properties of porous electrodes. Constitutive models were developed to describe the stress-strain response of electrodes under uniaxial tensile and compressive loads. The failure criterion and a damage model were introduced to model their unique tensile and compressive failure behavior. The failure mechanism of LIB electrodes was studied using the blunt rod test on dry electrodes, and numerical models were built to simulate progressive failure. The different failure processes were examined and analyzed in detail numerically, and correlated with experimentally observed failure phenomena. The test results and models improve our understanding of failure behavior in LIB electrodes, and provide constructive insights on future development of physics-based safety design tools for battery structures under mechanical abuse.

Constitutive behavior and progressive mechanical failure of electrodes in lithium-ion batteries

DOE PAGES

Zhang, Chao; Xu, Jun; Cao, Lei; ...

2017-05-05

The electrodes of lithium-ion batteries (LIB) are known to be brittle and to fail earlier than the separators during an external crush event. Thus, the understanding of mechanical failure mechanism for LIB electrodes (anode and cathode) is critical for the safety design of LIB cells. In this paper, we present experimental and numerical studies on the constitutive behavior and progression of failure in LIB electrodes. Mechanical tests were designed and conducted to evaluate the constitutive properties of porous electrodes. Constitutive models were developed to describe the stress-strain response of electrodes under uniaxial tensile and compressive loads. The failure criterion andmore » a damage model were introduced to model their unique tensile and compressive failure behavior. The failure mechanism of LIB electrodes was studied using the blunt rod test on dry electrodes, and numerical models were built to simulate progressive failure. The different failure processes were examined and analyzed in detail numerically, and correlated with experimentally observed failure phenomena. Finally, the test results and models improve our understanding of failure behavior in LIB electrodes, and provide constructive insights on future development of physics-based safety design tools for battery structures under mechanical abuse.« less

Getting Comfortable with Failure and Vulnerability to Facilitate Learning and Innovation in the Game of School

ERIC Educational Resources Information Center

Machajewski, Szymon

2017-01-01

Schools are to prepare students for success. However, they often villainize failure. Instead, schools should teach students how to fail fast and safely in order to learn and to allow innovation through vulnerability. The lessons that the gaming culture has for learning will define future strategies of teaching and learning. Games are sometimes…

Planning & Priority Setting for Basic Research

DTIC Science & Technology

2010-05-05

Integrated into numerous commercial codes in aerospace, automotive , semiconductor, and chemical industries Fast Multipole Methods (ONR 31) Applications... Use knowledge (even failures) to reduce risk in acquisition Provide the basis for future Navy and arine Corps syste s Ensure research...relevancy to Naval S&T strategy Transition pro ising Basic Research to applications Use kno ledge (even failures) to reduce risk in acquisition Maintain

Comparing two survey methods for estimating maternal and perinatal mortality in rural Cambodia.

PubMed

Chandy, Hoeuy; Heng, Yang Van; Samol, Ha; Husum, Hans

2008-03-01

We need solid estimates of maternal mortality rates (MMR) to monitor the impact of maternal care programs. Cambodian health authorities and WHO report the MMR in Cambodia at 450 per 100,000 live births. The figure is drawn from surveys where information is obtained by interviewing respondents about the survival of all their adult sisters (sisterhood method). The estimate is statistically imprecise, 95% confidence intervals ranging from 260 to 620/100,000. The MMR estimate is also uncertain due to under-reporting; where 80-90% of women deliver at home maternal fatalities may go undetected especially where mortality is highest, in remote rural areas. The aim of this study was to attain more reliable MMR estimates by using survey methods other than the sisterhood method prior to an intervention targeting obstetric rural emergencies. The study was carried out in rural Northwestern Cambodia where access to health services is poor and poverty, endemic diseases, and land mines are endemic. Two survey methods were applied in two separate sectors: a community-based survey gathering data from public sources and a household survey gathering data direct from primary sources. There was no statistically significant difference between the two survey results for maternal deaths, both types of survey reported mortality rates around the public figure. The household survey reported a significantly higher perinatal mortality rate as compared to the community-based survey, 8.6% versus 5.0%. Also the household survey gave qualitative data important for a better understanding of the many problems faced by mothers giving birth in the remote villages. There are detection failures in both surveys; the failure rate may be as high as 30-40%. PRINCIPLE CONCLUSION: Both survey methods are inaccurate, therefore inappropriate for evaluation of short-term changes of mortality rates. Surveys based on primary informants yield qualitative information about mothers' hardships important for the design of future maternal care interventions.

Influence of Unloading Rate on the Strainburst Characteristics of Beishan Granite Under True-Triaxial Unloading Conditions

NASA Astrophysics Data System (ADS)

Zhao, X. G.; Wang, J.; Cai, M.; Cheng, C.; Ma, L. K.; Su, R.; Zhao, F.; Li, D. J.

2014-03-01

Rockburst is a sudden and violent failure of rocks and it often occurs in hard rocks in highly stressed ground. Strainburst is classified as one type of rockburst and it often occurs in rocks near or at the excavation boundary. Deep insight into the strainburst phenomenon is essential for safe underground construction at depth. In this paper, an experimental laboratory study on the strainburst behavior of Beishan granite is presented. Based on in-situ stress measurement data from the Beishan area in China, a series of tests under different unloading rates were performed to investigate the strainburst process using a true-triaxial strainburst test system which was equipped with an acoustic emission (AE) monitoring system. In addition, a high-speed video camera was used to record and visualize the initiation and ejection of rock fragments as well as the sudden dynamic failure (strainburst) of the test samples. AE characteristics associated with the cumulative energy and frequency-amplitude distributions were analyzed. Characteristics of the microscopic structure of a fragment generated from one test were observed using a scanning electron microscope. The experimental results indicate that the degree of violence during failure and the associated AE energy release in the strainburst process are dependent on the unloading rate. When the unloading rate is high, the rock is prone to strainburst. On the other hand, as the unloading rate decreases, the failure mode changes from strainburst to spalling. In addition, the cumulative AE energy is not sensitive to unloading rates greater than 0.05 MPa/s. When the unloading rate is less than 0.05 MPa/s, the cumulative AE energy shows a marked decreasing trend during rock failure.

Meta-analysis of Timing for Microsurgical Free-Flap Reconstruction for Lower Limb Injury: Evaluation of the Godina Principles.

PubMed

Haykal, Siba; Roy, Mélissa; Patel, Ashit

2018-05-01

 In 1986, Marko Godina published his seminal work regarding the timing of free-flap reconstruction for traumatic extremity defects. Early reconstruction, compared with delayed and late reconstruction resulted in significant decreases in free-flap failure rate, post-operative infections, hospitalization time, bone healing time, and number of additional anesthesias. The objective of this manuscript was to evaluate whether these principles continue to apply.  A meta-analysis was performed analyzing articles from Medline, Embase, and Pubmed. Four hundred and ninety-two articles were screened, and 134 articles were assessed for eligibility. Following full-text review, 43 articles were included in this study.  The exact timing for free-flap reconstruction, free-flap failure rate, infection rate, and follow-up was defined in all 43 articles. Early free-flap reconstruction was found to have significantly lower rates of free-flap failure and infection in comparison to delayed reconstruction ( p  = 0.008; p  = 0.0004). Compared with late reconstruction, early reconstruction was found to have significantly lower infection rates only ( p  = 0.01) with no difference in free-flap failures rates. Early reconstruction was found to lead to fewer additional procedures ( p  = 0.03). No statistical significance was found for bone healing time or hospitalization time.  Early free-flap reconstruction performed within the first 72 hours resulted in a decreased rate of free-flap failures, infection, and additional procedures with no difference in other parameters. The largest majority of free flaps continue to be performed in a delayed time frame. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Comparison of three methods to identify the anaerobic threshold during maximal exercise testing in patients with chronic heart failure.

PubMed

Beckers, Paul J; Possemiers, Nadine M; Van Craenenbroeck, Emeline M; Van Berendoncks, An M; Wuyts, Kurt; Vrints, Christiaan J; Conraads, Viviane M

2012-02-01

Exercise training efficiently improves peak oxygen uptake (V˙O2peak) in patients with chronic heart failure. To optimize training-derived benefit, higher exercise intensities are being explored. The correct identification of anaerobic threshold is important to allow safe and effective exercise prescription. During 48 cardiopulmonary exercise tests obtained in patients with chronic heart failure (59.6 ± 11 yrs; left ventricular ejection fraction, 27.9% ± 9%), ventilatory gas analysis findings and lactate measurements were collected. Three technicians independently determined the respiratory compensation point (RCP), the heart rate turning point (HRTP) and the second lactate turning point (LTP2). Thereafter, exercise intensity (target heart rate and workload) was calculated and compared between the three methods applied. Patients had significantly reduced maximal exercise capacity (68% ± 21% of predicted V˙O2peak) and chronotropic incompetence (74% ± 7% of predicted peak heart rate). Heart rate, workload, and V˙O2 at HRTP and at RCP were not different, but at LTP2, these parameters were significantly (P < 0.0001) higher. Mean target heart rate and target workload calculated using the LTP2 were 5% and 12% higher compared with those calculated using HRTP and RCP, respectively. The calculation of target heart rate based on LTP2 was 5% and 10% higher in 12 of 48 (25%) and 6 of 48 (12.5%) patients, respectively, compared with the other two methods. In patients with chronic heart failure, RCP and HRTP, determined during cardiopulmonary exercise tests, precede the occurrence of LTP2. Target heart rates and workloads used to prescribe tailored exercise training in patients with chronic heart failure based on LTP2 are significantly higher than those derived from HRTP and RCP.