Communication failures during clinical handovers lead to a poor patient outcome: Lessons from a case report.

PubMed

Manias, Elizabeth; Geddes, Fiona; Watson, Bernadette; Jones, Dorothy; Della, Phillip

2015-01-01

In the emergency department, communication failures occur in clinical handover due to the urgent, changing and unpredictable nature of care provision. We present a case report of a female patient who was assaulted, and identify how various factors interacted to produce communication failures at multiple clinical handovers, leading to a poor patient outcome. Several handovers created many communication failures at diverse time points. The bedside medical handover produced misunderstandings during verbal exchange of information between emergency department consultants and junior doctors, and there was miscommunication involving plastic registrars. There was a failure in adequately informing the general practitioner and the patient relating to follow-up care after discharge. Deficiencies of communication occurred with conveying changes in an investigative report. Communication could be improved by dividing the conduct of handover in a quiet room and at the bedside, ensuring multiple sources of information are used and encouraging role-modelling behaviours for junior clinicians.

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.

Failure analysis of braided U-shaped metal bellows flexible hoses

NASA Astrophysics Data System (ADS)

Pierce, Stephen O.

Most of the research performed extensively reviews the effects of non-reinforced metal bellows and their pressurized characteristics. However, the majority of flex hoses are manufactured with reinforcement by the means of interweaved wire braids. For this research, the outer braid reinforced metal bellows flex hoses will be examined for their failure at differing lengths. The relationship with the bellows expansion joints is such that as the length of the flex hoses increases, the pressure at which squirm occurs decreases. As such, for the testing being performed, the same approach to failure is expected. As the length of the flex hose increases, it is predicted that the hose will fail at a decreasing pressure. Since the braid is the only thing that prevents the squirm from occurring, more of the load will be displaced from the bellows and into the braid. This will ultimately cause failure of the braid to occur at a lower pressure as the length of the hoses increase due to more of the load being transmitted from the bellows and into the braid.

A diagnosis system using object-oriented fault tree models

NASA Technical Reports Server (NTRS)

Iverson, David L.; Patterson-Hine, F. A.

1990-01-01

Spaceborne computing systems must provide reliable, continuous operation for extended periods. Due to weight, power, and volume constraints, these systems must manage resources very effectively. A fault diagnosis algorithm is described which enables fast and flexible diagnoses in the dynamic distributed computing environments planned for future space missions. The algorithm uses a knowledge base that is easily changed and updated to reflect current system status. Augmented fault trees represented in an object-oriented form provide deep system knowledge that is easy to access and revise as a system changes. Given such a fault tree, a set of failure events that have occurred, and a set of failure events that have not occurred, this diagnosis system uses forward and backward chaining to propagate causal and temporal information about other failure events in the system being diagnosed. Once the system has established temporal and causal constraints, it reasons backward from heuristically selected failure events to find a set of basic failure events which are a likely cause of the occurrence of the top failure event in the fault tree. The diagnosis system has been implemented in common LISP using Flavors.

Lessons in Leadership...: How to Deal with Failure

ERIC Educational Resources Information Center

Lassiter, Wright

2008-01-01

So much of the good in the world is due to people who did not give up. Every wonderful invention, every positive belief turned into positive action is the direct result of someone who did not give up. Everyone is going to fail once in a while, no matter how hard they try not to. The important thing is how a person responds when failure occurs. In…

Effects of surface removal on rolling-element fatigue

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin V.

1987-01-01

The Lundberg-Palmgren equation was modified to show the effect on rolling-element fatigue life of removing by grinding a portion of the stressed volume of the raceways of a rolling-element bearing. Results of this analysis show that depending on the amount of material removed, and depending on the initial running time of the bearing when material removal occurs, the 10-percent life of the reground bearings ranges from 74 to 100 percent of the 10-percent life of a brand new bearing. Three bearing types were selected for testing. A total of 250 bearings were reground. Of this matter, 30 bearings from each type were endurance tested to 1600 hr. No bearing failure occurred related to material removal. Two bearing failures occurred due to defective rolling elements and were typical of those which may occur in new bearings.

Cost analysis of equipment failure of a radiology department and possible choices about maintenance.

PubMed

Grisi, Guido; Dalla Palma, Ludovico; Rimondini, Allesandra; Palmolungo, Chiara; Cuttin Zernich, Roberto; Pozzi Mucelli, Roberto

2002-01-01

Our aim was to evaluate the economic impact of equipment failures in a radiology department with a view to guiding maintenance policy decisions. We assessed the negative economic impact caused by the interruption of activity of a radiodiagnostics section due to equipment failure, taking into account: the effects occurring during the first day of equipment down-time (assuming that the equipment failure occurs in the middle of the shift) and the effects during the following days until the repair of the failure; the effects occurring in the short- and long-term. To exemplify the negative impact of inactivity due to equipment failure, we chose three radiology sections with different levels of technological and operational complexity (chest radiology, gastrointestinal radiology and remote-controlled diagnostics). For each, we evaluated the loss of contribution margin and the idle capacity costs (short- and long-term impact). The negative economic effects were: for thoracic radiology, 496,77 Euro in the first day, and 30,99 Euro from the second day onwards; for gastrointestinal radiology, 526,40 Euro for the first day, and 730,39 Euro from the second day onwards; for remote-controlled diagnostics, 786,25 Euro for the first day, and 927,67 Euro from the second days onwards. Our results indicate that the level of idle capacity costs (mainly equipment and staff) increases with the complexity of the equipment, whereas the contribution margin appears to fluctuate, because the charges are state-imposed and do not vary with the complexity of equipment. Moreover, our analysis shows that if the workload of a broken machine can easily be assigned to an additional shift using another machine, losses are considerably reduced from the second day onwards. Once the negative economic impact of equipment failures has been evaluated, the second step is to choose the best kind of maintenance. A sound calculation of the economic impact of equipment failures is very useful for guiding the head of department and the hospital manager in deciding whether to purchase maintenance services (or a long-term guarantee) from the equipment manufacturer, to set up an auxiliary centre for maintenance and repair, or to purchase a third-party maintenance contract.

Liver physiological polyploidization: MicroRNA-122 a key regulator.

PubMed

Celton-Morizur, Séverine; Desdouets, Chantal

2017-03-01

Polyploidy is defined as an increase in genome DNA content and is observed in all mammalian species. Polyploidy is a common characteristic of hepatocytes. Polyploidization occurs mainly during liver development, but also in adults with increasing age or due to cellular stress. During liver development, hepatocytes polyploidization occurs through cytokinesis failure leading to the genesis of binucleate hepatocytes. Recently, Hsu et al. demonstrated that miR-122 is a key regulator of hepatic binucleation. In fact, during liver development, miR-122 directly antagonizes procytokinesis targets and thus induces cytokinesis failure leading to the genesis of binucleate hepatocytes. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Failure of Non-Circular Composite Cylinders

NASA Technical Reports Server (NTRS)

Hyer, M. W.

2004-01-01

In this study, a progressive failure analysis is used to investigate leakage in internally pressurized non-circular composite cylinders. This type of approach accounts for the localized loss of stiffness when material failure occurs at some location in a structure by degrading the local material elastic properties by a certain factor. The manner in which this degradation of material properties takes place depends on the failure modes, which are determined by the application of a failure criterion. The finite-element code STAGS, which has the capability to perform progressive failure analysis using different degradation schemes and failure criteria, is utilized to analyze laboratory scale, graphite-epoxy, elliptical cylinders with quasi-isotropic, circumferentially-stiff, and axially-stiff material orthotropies. The results are divided into two parts. The first part shows that leakage, which is assumed to develop if there is material failure in every layer at some axial and circumferential location within the cylinder, does not occur without failure of fibers. Moreover before fibers begin to fail, only matrix tensile failures, or matrix cracking, takes place, and at least one layer in all three cylinders studied remain uncracked, preventing the formation of a leakage path. That determination is corroborated by the use of different degradation schemes and various failure criteria. Among the degradation schemes investigated are the degradation of different engineering properties, the use of various degradation factors, the recursive or non-recursive degradation of the engineering properties, and the degradation of material properties using different computational approaches. The failure criteria used in the analysis include the noninteractive maximum stress criterion and the interactive Hashin and Tsai-Wu criteria. The second part of the results shows that leakage occurs due to a combination of matrix tensile and compressive, fiber tensile and compressive, and inplane shear failure modes in all three cylinders. Leakage develops after a relatively low amount of fiber damage, at about the same pressure for three material orthotropies, and at approximately the same location.

Fission Limit And Surface Disruption Criteria For Asteroids: The Case Of Kleopatra

NASA Astrophysics Data System (ADS)

Hirabayashi, Masatoshi; Scheeres, D. J.

2012-05-01

Asteroid structural failure due to a rapid rotation may occur by two fundamentally different ways: by spinning so fast that surface particles are lofted off due to centripetal accelerations overcoming gravitational attractions or through fission of the body. We generalize these failure modes for real asteroid shapes. How a rubble pile asteroid will fail depends on which of these failure criterion occur first if its spin rate is increased due to the YORP effect, impacts, or planetary flybys. The spin rate at which the interior of an arbitrary uniformly rotating body will undergo tension (and conservatively be susceptible to fission) is computed by taking planar cuts through the shape model, computing the mutual gravitational attraction between the two segments, and determining the spin rate at which the centrifugal force between the two components equals the mutual gravitational attraction. The gravitational attraction computation uses an improved version of the algorithm presented in Werner et al. (2005). To determine the interior point that first undergoes tension, we consider this planar cut perpendicular to the axis of minimum moment of inertia at different cross-sections. On the other hand, we define the surface disruption as follows. For an arbitrary body uniformly rotating at a constant spin rate there are at least four synchronous orbits, which represent circular orbits with the same period as the asteroid spin rate. Surface disruption occurs when the body spins fast enough so that at least one of these synchronous orbits touches the asteroid surface. Kleopatra currently spins with a period of 5.38 hours. The spin period for surface disruption is computed to be 3.02 hours, while the spin period for the interior of the asteroid to go into tension is about 4.8 hours. Thus Kleopatra’s internal fission could occur at spin periods longer than when surface disruption occurs.

True Triaxial Failure of Granite: Implications for Deep Borehole Waste Disposal

NASA Astrophysics Data System (ADS)

Williams, M.; Ingraham, M. D.; Cheung, C.; Haimson, B. C.

2016-12-01

A series of tests have been completed to determine the failure of Sierra White Granite under a range of true triaxial stress conditions ranging from axisymmetric compression to axisymmetric extension. Tests were performed under constant mean stress conditions. Results show a significant difference in failure due to the intermediate principal stress. Borehole breakout, a significant issue for deep borehole disposal, occurs in line with the least principal stress, which in the United States at great depth is almost certainly a horizontal stress. This means that any attempt to dispose of waste in deep boreholes will have to overcome this phenomenon. This work seeks to determine the full 3D failure surface for granite such that it can be applied to determining the likelihood of borehole breakout occurring under different stress conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Inclusion Body Myositis: A Case Presenting with Respiratory Failure and Autopsy Findings Leading to the Hypothesis of a Paraneoplastic Cause.

PubMed

Dardis, Christopher; Antezana, Ariel; Tanji, Kurenai; Maccabee, Paul J

2017-06-23

BACKGROUND Sporadic inclusion body myositis (IBM) is the most common acquired myopathy seen in adults aged over 50 years, with a prevalence estimated at between 1 and 70 per million. Weakness of the diaphragm with loss of vital capacity is almost universal in IBM. This is almost always asymptomatic. When respiratory complications occur, they are most often due to aspiration. Respiratory failure due to diaphragmatic weakness is exceptionally rare, particularly as the presenting symptom of the disease. It is not currently considered to be a paraneoplastic syndrome. CASE REPORT Our patient presented with hypercarbic respiratory failure. This is the first such reported case without signs of weakness elsewhere of which we are aware. We suspected IBM based on her history of progressive weakness and findings on electromyography. There was a delay of 5 years in obtaining biopsy for confirmation, during which she presented with recurrent episodes of respiratory failure despite using non-invasive ventilation. An autopsy revealed the presence of papillary thyroid carcinoma with spread to local lymph nodes. On the basis that these co-morbidities are unlikely to have occurred by chance (we estimate 1×10-17), we hypothesize that IBM may be a paraneoplastic condition. We acknowledge that proof would require demonstrating a pathogenic antibody. CONCLUSIONS IBM should be considered in older patients (age >45) presenting with otherwise unexplained respiratory failure. A workup for possible malignancy in this setting appears reasonable.

Evaluation of ball and roller bearings restored by grinding

NASA Technical Reports Server (NTRS)

Parker, R. J.; Zaretsky, E. V.; Chen, S. M.

1976-01-01

A joint program was undertaken to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. Groups of each of these bearings were visually and dimensionally inspected for suitability for restoration. A total of 250 bearings were restored by grinding. Of this number, 30 bearings from each type were endurance tested to a TBO of 1600 hours. No bearing failures occurred related to the restoration by grinding process. The two bearing failures which occurred were due to defective rolling elements and were typical of those which may occur in new bearings. The restorable component yield to the three groups was in excess of 90 percent.

Evaluation of ball and roller bearings restored by grinding

NASA Technical Reports Server (NTRS)

Parker, R. J.; Zaretsky, E. V.; Chen, S. M.

1976-01-01

The restoration by grinding of those rolling element bearings which are currently being discarded at aircaft engine and transmission overhaul is considered. Three bearing types were selected from the UH-1 helicopter engine and transmission for the pilot program. Groups of each of these bearings were visually and dimensionally inspected for suitability for restoration. A total of 250 bearings were restored by grinding. Of this number, 30 bearings from each type were endurance tested to a TBO of 1600 hours. No bearing failures occurred related to the restoration by grinding process. The two bearing failures which occurred were due to defective rolling elements and were typical of those which may occur in new bearings. The restorable component yield to the three groups was in excess of 90 percent.

Relation of submarine landslide to hydrate occurrences in Baiyun Depression, South China Sea

NASA Astrophysics Data System (ADS)

Sun, Yunbao; Zhang, Xiaohua; Wu, Shiguo; Wang, Lei; Yang, Shengxiong

2018-02-01

Submarine landslides have been observed in the Baiyun Depression of the South China Sea. The occurrence of hydrates below these landslides indicates that these slope instabilities may be closely related to the massive release of methane. In this study, we used a simple Monte-Carlo model to determine the first-order deformation pattern of a gravitationally destabilizing slope. The results show that a stress concentration occurs due to hydrate dissociation on the nearby glide surface and on top of a gas chimney structure. Upon the dissolution of the gas hydrate, slope failure occurs due to the excess pore pressure generated by the dissociation of the gas hydrates. When gas hydrates dissociate at shallow depths, the excess pore pressure generated can be greater than the total stress acting at those points, along with the forces that resist sliding. Initially, the failure occurs at the toe of the slope, then extends to the interior. Although our investigation focused only on the contribution of hydrate decomposition to submarine landslide, this process is also affected by both the slope material properties and topography.

Simultaneous Bilateral Quadriceps Tendon Rupture in Patient with Chronic Renal Failure

PubMed Central

Lee, Yunseok; Kim, Byounggook; Chung, Ju-Hwan

2011-01-01

Simultaneous bilateral spontaneous rupture of the quadriceps tendon is a very rare condition and only a few cases have been reported in the literature. The etiology is not clear yet. But it occurs infrequently in patients with chronic metabolic disorders. A 30-year-old female patient with simultaneous bilateral spontaneous quadriceps tendon rupture visited our hospital. She had chronic renal failure and her parathyroid hormone level was elevated due to parathyroid adenoma. We report a surgical repair of both quadriceps tendons of a patient with chronic renal failure as well as management of hyperparathyroidism. PMID:22570843

7 CFR 760.611 - Qualifying losses, eligible causes and types of loss.

Code of Federal Regulations, 2010 CFR

2010-01-01

... final planting date; (4) The cause of loss was due to water contained or released by any governmental... containment or release of the water; (5) The cause of loss was due to conditions or events occurring outside...) Losses caused by a failure of power supply or brownout as defined in § 760.602; (2) Losses caused by the...

Instrument and spacecraft faults associated with nuclear radiation in space

NASA Technical Reports Server (NTRS)

Trainos, J. H.

1994-01-01

A review is given which surveys the variety of faults and failures which have occurred in space due both to the effects of single, energetic nuclear particles, as well as effects due to the accumulated ionizing dose or the fluence of nuclear particles. The review covers a variety of problems with sensors, electronics, instruments and spacecraft from several countries.

ANALYSIS OF LABOUR ACCIDENTS OCCURRING IN DISASTER RESTORATION WORK FOLLOWING THE NIIGATA CHUETSU EARTHQUAKE (2004) AND THE NIIGATA CHUETSU-OKI EARTHQUAKE (2007)

NASA Astrophysics Data System (ADS)

Itoh, Kazuya; Noda, Masashi; Kikkawa, Naotaka; Hori, Tomohito; Tamate, Satoshi; Toyosawa, Yasuo; Suemasa, Naoaki

Labour accidents in disaster-relief and disaster restoration work following the Niigata Chuetsu Earthquake (2004) and the Niigata Chuetsu-oki Earthquake (2007) were analysed and characterised in order to raise awareness of the risks and hazards in such work. The Niigata Chuetsu-oki Earthquake affected houses and buildings rather than roads and railways, which are generally disrupted due to landslides or slope failures caused by earthquakes. In this scenario, the predominant type of accident is a "fall to lower level," which increases mainly due to the fact that labourers are working to repair houses and buildings. On the other hand, landslides and slope failures were much more prevalent in the Niigata Chuetsu Earthquake, resulting in more accidents occurring in geotechnical works rather than in construction works. Therefore, care should be taken in preventing "fall to lower level" accidents associated with repair work on the roofs of low-rise houses, "cut or abrasion" accidents due to the demolition of damaged houses and "caught in or compressed by equipment" accidents in road works and water and sewage works.

Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

NASA Astrophysics Data System (ADS)

Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

2012-01-01

We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.

Failure mechanism of hollow tree trunks due to cross-sectional flattening

PubMed Central

Huang, Yan-San; Hsu, Fu-Lan; Lee, Chin-Mei

2017-01-01

Failure of hollow trees in urban areas is a worldwide concern, and it can be caused by different mechanisms, i.e. bending stresses or flattening-related failures. Here we derive a new analytical expression for predicting the bending moment for tangential cracking, and compare the breaking moment of various failure modes, including Brazier buckling, tangential cracking, shear failure and conventional bending failure, as a function of t/R ratio, where t and R are the trunk wall thickness and trunk radius, respectively, of a hollow tree. We use Taiwan red cypress as an example and show that its failure modes and the corresponding t/R ratios are: Brazier buckling (Mode I), tangential cracking followed by longitudinal splitting (Mode II) and conventional bending failure (Mode III) for 0 < t/R < 0.06, 0.06 < t/R < 0.27 and 0.27 < t/R < 1, respectively. The exact values of those ratios may vary within and among species, but the variation is much smaller than individual mechanical properties. Also, shear failure, another type of cracking due to maximum shear stress near the neutral axis of the tree trunk, is unlikely to occur since it requires much larger bending moments. Hence, we conclude that tangential cracking due to cross-sectional flattening, followed by longitudinal splitting, is dominant for hollow trunks. Our equations are applicable to analyse straight hollow tree trunks and plant stems, but are not applicable to those with side openings or those with only heart decay. Our findings provide insights for those managing trees in urban situations and those managing for conservation of hollow-dependent fauna in both urban and rural settings. PMID:28484616

Two-dimensional nonlinear finite element analysis of well damage due to reservoir compaction, well-to-well interactions, and localization on weak layers

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

Hilbert, L.B. Jr.; Fredrich, J.T.; Bruno, M.S.

1996-05-01

In this paper the authors present the results of a coupled nonlinear finite element geomechanics model for reservoir compaction and well-to-well interactions for the high-porosity, low strength diatomite reservoirs of the Belridge field near Bakersfield, California. They show that well damage and failures can occur under the action of two distinct mechanisms: shear deformations induced by pore compaction, and subsidence, and shear deformations due to well-to-well interactions during production or water injection. They show such casting damage or failure can be localized to weak layers that slide or slip under shear due to subsidence. The magnitude of shear displacements andmore » surface subsidence agree with field observations.« less

Rock-slope failure activity and geological crises in western Norway

NASA Astrophysics Data System (ADS)

Hilger, Paula; Hermanns, Reginald L.; Myhra, Kristin S.; Gosse, John C.; Ivy-Ochs, Susan; Etzelmüller, Bernd

2017-04-01

In Norway a compilation of terrestrial cosmogenic nuclide (TCN) ages of rock-avalanche deposits suggests a close link of rock-slope failures related to deglaciation. Although ages spread over several thousand years at the end of the Late Pleistocene, 50% of all documented events occurred within 1000 years after deglaciation. It is therefore likely that debuttressing triggered most of the events. The same data set suggests that 25% of the events occurred during a period stretching until the Holocene thermal maximum (HTM). These events might be interpreted as possible reactions to additional factors such as the thawing of high-altitude permafrost. An example of a geological crisis following deglaciation and before the HTM are seven lobate rock-avalanche deposits mapped under the slope of the Vora mountain (1450 m asl.) in the Nordfjord area of western Norway. Three events of this rock-slope failure cluster date within a short time period of 2000 years, where modelling studies indicate that high-altitude permafrost was present. After the HTM rock-slope failures are distributed temporally and spatially rather evenly throughout the Holocene and western Norway. But there are two independent local clusters with frequent rock slides during a short time span. (1) At the active Mannen rock-slope instability several rock-avalanche and rockslide deposits were mapped on the valley bottom. Stratigraphic relations combined with TCN dating suggest that at least one event occurred when the valley bottom was below the marine limit. TCN ages of further four lobes cluster around 5.2 ka BP, which does not coincide with any other rock-avalanche occurrence in the region. The top of the north facing 1295 m high unstable slope concurs with the currently estimated permafrost boundary. Preliminary TCN ages of the sliding surface indicate that larger parts of the mountain did not become active until the climate maximum. It is likely that due to structural complexity not allowing for any easy kinematic failure process, it required several thousand years of rock-slope deformation prior to the multiple failures. (2) The youngest independent rock-avalanche cluster is historic with 5 rock avalanches sourcing from Ramnefjellet in 1905, 1936 (three events), and 1950 entering into Loen lake in western Norway. Subsequent displacement waves killed 61 people in 1905 and 73 people due to the first failure in 1936. The back scarp does not exceed 850 m elevation and lies hence below the present day and Little Ice Age permafrost limit. It is therefore unlikely that permafrost dynamics contribute to this sequence of rock-slope failures. Local clusters or a geological crisis by rock-slope failures seems to be related to different main factors, such as glacial debutressing, influence of ground thermal regime changes (Mannen) and probably more disconnected to major climate variability (Loen). For an integrated risk management it is therefore important to understand that large rock-slope failures do not necessarily have to occur in single events but can occur over several decades or centuries and thus complicate severely land use management after catastrophic events.

Loeffler Endocarditis: A Unique Presentation of Right-Sided Heart Failure Due to Eosinophil-Induced Endomyocardial Fibrosis.

PubMed

Alam, Amit; Thampi, Shankar; Saba, Shahryar G; Jermyn, Rita

2017-01-01

Loeffler endocarditis is a rare restrictive cardiomyopathy caused by abnormal endomyocardial infiltration of eosinophils, with subsequent tissue damage from degranulation, eventually leading to fibrosis. Although an uncommon entity, it is still a disease with significant morbidity and mortality. Often identified only at late stages, treatment options are limited once fibrosis occurs, usually requiring heart failure medications or surgical intervention. We present a unique case of a woman with remote history of hypereosinophilic syndrome, attributed to treatment of rheumatoid arthritis with infliximab, who presented with symptoms of heart failure refractory to medical management and was found to have Loeffler endocarditis. The severe progression of the disease required surgical intervention with endocardial stripping to treat the right-sided diastolic heart failure.

Risk management.

PubMed

Chambers, David W

2010-01-01

Every plan contains risk. To proceed without planning some means of managing that risk is to court failure. The basic logic of risk is explained. It consists in identifying a threshold where some corrective action is necessary, the probability of exceeding that threshold, and the attendant cost should the undesired outcome occur. This is the probable cost of failure. Various risk categories in dentistry are identified, including lack of liquidity; poor quality; equipment or procedure failures; employee slips; competitive environments; new regulations; unreliable suppliers, partners, and patients; and threats to one's reputation. It is prudent to make investments in risk management to the extent that the cost of managing the risk is less than the probable loss due to risk failure and when risk management strategies can be matched to type of risk. Four risk management strategies are discussed: insurance, reducing the probability of failure, reducing the costs of failure, and learning. A risk management accounting of the financial meltdown of October 2008 is provided.

Complications with the MICRA TPS Pacemaker System: Persistent Complete Heart Block and Late Capture Failure.

PubMed

Holm, Niels; Müller, Andreas; Zbinden, Rainer

2017-04-01

A Medtronic MICRA transcatheter pacing system (Medtronic, Minneapolis, MN, USA) was implanted in an 86-year-old patient with sick sinus syndrome and left bundle branch block after transfemoral aortic valve implantation. During implantation she developed a persistent complete heart block due to manipulation with the large-bore delivery catheter. Two weeks later, acute pacemaker dysfunction occurred due to massive increase of pacing threshold and impedance without obvious pacemaker dislocation or myocardial perforation. Recurrent capture failure was seen with pacing output set at 5 V/1.0 ms. Hence, microdislocation or fixation of the tines in the right ventricular trabeculae has to be assumed. © 2016 Wiley Periodicals, Inc.

Continuous noninvasive ventilation delivered by a novel total face mask: a case series report.

PubMed

Belchior, Inês; Gonçalves, Miguel R; Winck, João Carlos

2012-03-01

Noninvasive ventilation (NIV) has been widely used to decrease the complications associated with tracheal intubation in mechanically ventilated patients. However, nasal ulcerations may occur when conventional masks are used for continuous ventilation. A total face mask, which has no contact with the more sensitive areas of the face, is a possible option. We describe 3 patients with acute respiratory failure due to amyotrophic lateral sclerosis, who developed nasal bridge skin necrosis during continuous NIV, and one patient with post-extubation respiratory failure due to a high spinal cord injury, who had facial trauma with contraindication for conventional mask use. The total face mask was very well tolerated by all the patients, and permitted safe and efficient continuous NIV for several days until the acute respiratory failure episode resolved. None of the patients required endotracheal intubation during the acute episode.

Root Cause Failure Analysis of Stator Winding Insulation failure on 6.2 MW hydropower generator

NASA Astrophysics Data System (ADS)

Adhi Nugroho, Agus; Widihastuti, Ida; Ary, As

2017-04-01

Insulation failure on generator winding insulation occurred in the Wonogiri Hydropower plant has caused stator damage since ase was short circuited to ground. The fault has made the generator stop to operate. Wonogiri Hydropower plant is one of the hydroelectric plants run by PT. Indonesia Power UBP Mrica with capacity 2 × 6.2 MW. To prevent damage to occur again on hydropower generators, an analysis is carried out using Root Cause Failure Analysis RCFA is a systematic approach to identify the root cause of the main orbasic root cause of a problem or a condition that is not wanted. There are several aspects to concerned such as: loading pattern and operations, protection systems, generator insulation resistance, vibration, the cleanliness of the air and the ambient air. Insulation damage caused by gradual inhomogeneous cooling at the surface of winding may lead in to partial discharge. In homogeneous cooling may present due to lattice hampered by dust and oil deposits. To avoid repetitive defects and unwanted condition above, it is necessary to perform major maintenance overhaul every 5000-6000 hours of operation.

Cardiorenal Syndrome in Acute Heart Failure: Revisiting Paradigms.

PubMed

Núñez, Julio; Miñana, Gema; Santas, Enrique; Bertomeu-González, Vicente

2015-05-01

Cardiorenal syndrome has been defined as the simultaneous dysfunction of both the heart and the kidney. Worsening renal function that occurs in patients with acute heart failure has been classified as cardiorenal syndrome type 1. In this setting, worsening renal function is a common finding and is due to complex, multifactorial, and not fully understood processes involving hemodynamic (renal arterial hypoperfusion and renal venous congestion) and nonhemodynamic factors. Traditionally, worsening renal function has been associated with worse outcomes, but recent findings have revealed mixed and heterogeneous results, perhaps suggesting that the same phenotype represents a diversity of pathophysiological and clinical situations. Interpreting the magnitude and chronology of renal changes together with baseline renal function, fluid overload status, and clinical response to therapy might help clinicians to unravel the clinical meaning of renal function changes that occur during an episode of heart failure decompensation. In this article, we critically review the contemporary evidence on the pathophysiology and clinical aspects of worsening renal function in acute heart failure. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Documenting Liquefaction Failures Using Satellite Remote Sensing and Artificial Intelligence Algorithms

NASA Astrophysics Data System (ADS)

Oommen, T.; Baise, L. G.; Gens, R.; Prakash, A.; Gupta, R. P.

2009-12-01

Historically, earthquake induced liquefaction is known to have caused extensive damage around the world. Therefore, there is a compelling need to characterize and map liquefaction after a seismic event. Currently, after an earthquake event, field-based mapping of liquefaction is sporadic and limited due to inaccessibility, short life of the failures, difficulties in mapping large aerial extents, and lack of resources. We hypothesize that as liquefaction occurs in saturated granular soils due to an increase in pore pressure, the liquefaction related terrain changes should have an associated increase in soil moisture with respect to the surrounding non-liquefied regions. The increase in soil moisture affects the thermal emittance and, hence, change detection using pre- and post-event thermal infrared (TIR) imagery is suitable for identifying areas that have undergone post-earthquake liquefaction. Though change detection using TIR images gives the first indication of areas of liquefaction, the spatial resolution of TIR images is typically coarser than the resolution of corresponding visible, near-infrared (NIR), and shortwave infrared (SWIR) images. We hypothesize that liquefaction induced changes in the soil and associated surface effects cause textural and spectral changes in images acquired in the visible, NIR, and SWIR. Although these changes can be from various factors, a synergistic approach taking advantage of the thermal signature variation due to changing soil moisture condition, together with the spectral information from high resolution visible, NIR, and SWIR bands can help to narrow down the locations of post-event liquefaction for regional documentation. In this study, we analyze the applicability of combining various spectral bands from different satellites (Landsat, Terra-MISR, IRS-1C, and IRS-1D) for documenting liquefaction failures associated with the magnitude 7.6 earthquake that occurred in Bhuj, India, in 2001. We combine the various spectral bands by neighborhood correlation image analysis using an artificial intelligence algorithm called support vector machine to remotely identify and document liquefaction failures across a region; and assess the reliability and accuracy of the thermal remote sensing approach in documenting regional liquefaction failures. Finally, we present the applicability of the satellite data analyzed and appropriateness of a multisensor and multispectral approach for documenting liquefaction related failures.

Cycle life test and failure model of nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.

1983-01-01

Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure.

Changes in electrical and thermal parameters of led packages under different current and heating stresses

NASA Astrophysics Data System (ADS)

Jayawardena, Adikaramge Asiri

The goal of this dissertation is to identify electrical and thermal parameters of an LED package that can be used to predict catastrophic failure real-time in an application. Through an experimental study the series electrical resistance and thermal resistance were identified as good indicators of contact failure of LED packages. This study investigated the long-term changes in series electrical resistance and thermal resistance of LED packages at three different current and junction temperature stress conditions. Experiment results showed that the series electrical resistance went through four phases of change; including periods of latency, rapid increase, saturation, and finally a sharp decline just before failure. Formation of voids in the contact metallization was identified as the underlying mechanism for series resistance increase. The rate of series resistance change was linked to void growth using the theory of electromigration. The rate of increase of series resistance is dependent on temperature and current density. The results indicate that void growth occurred in the cap (Au) layer, was constrained by the contact metal (Ni) layer, preventing open circuit failure of contact metal layer. Short circuit failure occurred due to electromigration induced metal diffusion along dislocations in GaN. The increase in ideality factor, and reverse leakage current with time provided further evidence to presence of metal in the semiconductor. An empirical model was derived for estimation of LED package failure time due to metal diffusion. The model is based on the experimental results and theories of electromigration and diffusion. Furthermore, the experimental results showed that the thermal resistance of LED packages increased with aging time. A relationship between thermal resistance change rate, with case temperature and temperature gradient within the LED package was developed. The results showed that dislocation creep is responsible for creep induced plastic deformation in the die-attach solder. The temperatures inside the LED package reached the melting point of die-attach solder due to delamination just before catastrophic open circuit failure. A combined model that could estimate life of LED packages based on catastrophic failure of thermal and electrical contacts is presented for the first time. This model can be used to make a-priori or real-time estimation of LED package life based on catastrophic failure. Finally, to illustrate the usefulness of the findings from this thesis, two different implementations of real-time life prediction using prognostics and health monitoring techniques are discussed.

14 CFR 25.981 - Fuel tank ignition prevention.

Code of Federal Regulations, 2010 CFR

2010-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.981 Fuel tank... system where catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by... established, as necessary, to prevent development of ignition sources within the fuel tank system pursuant to...

14 CFR 25.981 - Fuel tank ignition prevention.

Code of Federal Regulations, 2011 CFR

2011-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.981 Fuel tank... system where catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by... established, as necessary, to prevent development of ignition sources within the fuel tank system pursuant to...

14 CFR 25.981 - Fuel tank ignition prevention.

Code of Federal Regulations, 2012 CFR

2012-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.981 Fuel tank... system where catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by... established, as necessary, to prevent development of ignition sources within the fuel tank system pursuant to...

14 CFR 25.981 - Fuel tank ignition prevention.

Code of Federal Regulations, 2014 CFR

2014-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.981 Fuel tank... system where catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by... established, as necessary, to prevent development of ignition sources within the fuel tank system pursuant to...

14 CFR 25.981 - Fuel tank ignition prevention.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.981 Fuel tank... system where catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by... established, as necessary, to prevent development of ignition sources within the fuel tank system pursuant to...

The application of continuum damage mechanics to solve problems in geodynamics

NASA Astrophysics Data System (ADS)

Manaker, David Martin

Deformation within the Earth's lithosphere is largely controlled by the rheology of the rock. Ductile behavior in rocks is often associated with plasticity due to dislocation motion or diffusion under high pressures and temperatures. However, ductile behavior can also occur in brittle materials. An example would be cataclastic flow associated with folding at shallow crustal levels, steep subduction zones, and large-scale deformation at plate boundaries. Engineers utilize damage mechanics to model the continuum deformation of brittle materials. We utilize a modified form of damage mechanics where damage represents a reduction in frictional strength and includes a yield stress. We use this empirical approach to simulate the bending of the lithosphere. We use numerical simulations to obtain elastostatic solutions for plate bending and where the stress exceeds a yield stress, we apply damage to reduce the elastic moduli. Damage is calculated at each time step by a power-law relationship of the ratio of the yield stress to stress and the yield strain to the strain. To test our method, we apply our damage rheology to a plate deforming under applied shear, a constant bending moment, and a constant load. We simulate a wide range of behaviors from slow relaxation to instantaneous failure, over timescales that span six orders of magnitude. Stress relaxation produces elastic-perfectly plastic behavior in cases where failure does not occur. For cases of failure, we observe a rapid increase in damage leading to failure. The changes in the rate of damage accumulation in failure cases are similar to the changes in b-values of acoustic emissions observed in triaxial compression tests of fractured rock and b-value changes prior to some large earthquakes. Thus continuum damage mechanics can simulate ductile behavior due to brittle mechanisms as well as observations of laboratory experiments and seismicity.

Inclusion Body Myositis: A Case Presenting with Respiratory Failure and Autopsy Findings Leading to the Hypothesis of a Paraneoplastic Cause

PubMed Central

Dardis, Christopher; Antezana, Ariel; Tanji, Kurenai; Maccabee, Paul

2017-01-01

Patient: Female, 48 Final Diagnosis: Inclusion body myositis Symptoms: Shortness of breath • weakness Medication: — Clinical Procedure: Biopsy Specialty: Neurology Objective: Rare disease Background: Sporadic inclusion body myositis (IBM) is the most common acquired myopathy seen in adults aged over 50 years, with a prevalence estimated at between 1 and 70 per million. Weakness of the diaphragm with loss of vital capacity is almost universal in IBM. This is almost always asymptomatic. When respiratory complications occur, they are most often due to aspiration. Respiratory failure due to diaphragmatic weakness is exceptionally rare, particularly as the presenting symptom of the disease. It is not currently considered to be a paraneoplastic syndrome. Case Report: Our patient presented with hypercarbic respiratory failure. This is the first such reported case without signs of weakness elsewhere of which we are aware. We suspected IBM based on her history of progressive weakness and findings on electromyography. There was a delay of 5 years in obtaining biopsy for confirmation, during which she presented with recurrent episodes of respiratory failure despite using non-invasive ventilation. An autopsy revealed the presence of papillary thyroid carcinoma with spread to local lymph nodes. On the basis that these co-morbidities are unlikely to have occurred by chance (we estimate 1×10−17), we hypothesize that IBM may be a paraneoplastic condition. We acknowledge that proof would require demonstrating a pathogenic antibody. Conclusions: IBM should be considered in older patients (age >45) presenting with otherwise unexplained respiratory failure. A workup for possible malignancy in this setting appears reasonable. PMID:28642454

Biomechanical comparison of orthogonal versus parallel double plating systems in intraarticular distal humerus fractures.

PubMed

Atalar, Ata C; Tunalı, Onur; Erşen, Ali; Kapıcıoğlu, Mehmet; Sağlam, Yavuz; Demirhan, Mehmet S

2017-01-01

In intraarticular distal humerus fractures, internal fixation with double plates is the gold standard treatment. However the optimal plate configuration is not clear in the literature. The aim of this study was to compare the biomechanical stability of the parallel and the orthogonal anatomical locking plating systems in intraarticular distal humerus fractures in artificial humerus models. Intraarticular distal humerus fracture (AO13-C2) with 5 mm metaphyseal defect was created in sixteen artificial humeral models. Models were fixed with either orthogonal or parallel plating systems with locking screws (Acumed elbow plating systems). Both systems were tested for their stiffness with loads in axial compression, varus, valgus, anterior and posterior bending. Then plastic deformation after cyclic loading in posterior bending and load to failure in posterior bending were tested. The failure mechanisms of all the samples were observed. Stiffness values in every direction were not significantly different among the orthogonal and the parallel plating groups. There was no statistical difference between the two groups in plastic deformation values (0.31 mm-0.29 mm) and load to failure tests in posterior bending (372.4 N-379.7 N). In the orthogonal plating system most of the failures occurred due to the proximal shaft fracture, whereas in the parallel plating system failure occurred due to the shift of the most distal screw in proximal fragment. Our study showed that both plating systems had similar biomechanical stabilities when anatomic plates with distal locking screws were used in intraarticular distal humerus fractures in artificial humerus models. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

[Position of diuretics in the treatment of heart failure in light of current guidelines].

PubMed

Bury, Krzysztof; Nessler, Jadwiga

Diuretics are the longest-used drugs in heart failure after digoxin. This is due to their effect on the retention of sodium and an increase in the volume of fluid in the extracellular space secondary to neurohormonal and hemodynamic disorders occurs in heart failure, and their effectiveness in the treatment of symptomatic heart failure. Discontinuation of treatment with diuretics or use them in too small doses is one of the causes of exacerbation or acute heart failure.The effectiveness of most of diuretics does not confirm in the clinical trials, and the indications for their use are often based only on expert opinion. The effect of these drugs on morbidity and mortality in patients with HF was not examined. Diuretics reduce shortness of breath and swelling. For this reasons it is recom-mended to use them in patients with signs and symptoms of fluid retention regardless of the left ventricular ejection fraction.

Failure mechanisms of thermal barrier coatings exposed to elevated temperatures

NASA Technical Reports Server (NTRS)

Miller, R. A.; Lowell, C. E.

1982-01-01

The failure of a ZrO2-8%Y2O3/Ni-14% Al-0.1% Zr coating system on Rene 41 in Mach 0.3 burner rig tests was characterized. High flame and metal temperatures were employed in order to accelerate coating failure. Failure by delamination was shown to precede surface cracking or spalling. This type of failure could be duplicated by cooling down the specimen after a single long duration isothermal high temperature cycle in a burner rig or a furnace, but only if the atmosphere was oxidizing. Stresses due to thermal expansion mismatch on cooling coupled with the effects of plastic deformation of the bond coat and oxidation of the irregular bond coat are the probable life limiting factors. Heat up stresses alone could not fail the coating in the burner rig tests. Spalling eventually occurs on heat up but only after the coating has already failed through delamination.

Preventing Spacecraft Failures Due to Tribological Problems

NASA Technical Reports Server (NTRS)

Fusaro, Robert L.

2001-01-01

Many mechanical failures that occur on spacecraft are caused by tribological problems. This publication presents a study that was conducted by the author on various preventatives, analyses, controls and tests (PACTs) that could be used to prevent spacecraft mechanical system failure. A matrix is presented in the paper that plots tribology failure modes versus various PACTs that should be performed before a spacecraft is launched in order to insure success. A strawman matrix was constructed by the author and then was sent out to industry and government spacecraft designers, scientists and builders of spacecraft for their input. The final matrix is the result of their input. In addition to the matrix, this publication describes the various PACTs that can be performed and some fundamental knowledge on the correct usage of lubricants for spacecraft applications. Even though the work was done specifically to prevent spacecraft failures the basic methodology can be applied to other mechanical system areas.

Numerical investigation of contact stresses for fretting fatigue damage initiation

NASA Astrophysics Data System (ADS)

Bhatti, N. A.; Abdel Wahab, M.

2017-05-01

Fretting fatigue phenomena occurs due to interaction between contacting bodies under application of cyclic and normal loads. In addition to environmental conditions and material properties, the response at the contact interface highly depends on the combination of applied loads. High stress concentration is present at the contact interface, which can start the damage nucleation process. At the culmination of nucleation process several micro cracks are initiated, ultimately leading to the structural failure. In this study, effect of ratio of tangential to normal load on contact stresses, slip amplitude and damage initiation is studied using finite element analysis. The results are evaluated for Ruiz parameter as it involves the slip amplitude which in an important factor in fretting fatigue conditions. It is observed that tangential to normal load ratio influences the stick zone size and damage initiation life. Furthermore, it is observed that tensile stress is the most important factor that drives the damage initiation to failure for the cases where failure occurs predominantly in mode I manner.

Life expectancy for community-based patients with heart failure from time of diagnosis.

PubMed

James, Stephanie; Barton, David; O'Connell, Eoin; Voon, Victor; Murtagh, Gillian; Watson, Chris; Murphy, Theodore; Prendiville, Brian; Brennan, David; Hensey, Mark; O'Neill, Louisa; O'Hanlon, Rory; Waterhouse, Deirdre; Ledwidge, Mark; Gallagher, Joseph; McDonald, Kenneth

2015-01-15

Heart failure has been demonstrated in previous studies to have a dismal prognosis. However, the modern-day prognosis of patients with new onset heart failure diagnosed in the community managed within a disease management programme is not known. The purpose of this study is to report on prognosis of patients presenting with new onset heart failure in the community who are subsequently followed in a disease management program. A review of patients referred to a rapid access heart failure diagnostic clinic between 2002 and 2012 was undertaken. Details of diagnosis, demographics, medical history, medications, investigations and mortality data were analysed. A total of 733 patients were seen in Rapid Access Clinic for potential new diagnosis of incident of heart failure. 38.9% (n=285) were diagnosed with heart failure, 40.7% (n=116) with HF-REF and 59.3% (n=169) with HF-PEF. There were 84 (29.5%) deaths in the group of patients diagnosed with heart failure; 41 deaths (35.3%) occurred in patients with HF-REF and 43 deaths (25.4%) occurred in patients with HF-PEF. In patients with heart failure, 52.4% (n=44) died from cardiovascular causes. 63.8% of HF patients were alive after 5 years resulting on average in a month per year loss of life expectancy over that period compared with aged matched simulated population. In this community-based cohort, the prognosis of heart failure was better than reported in previous studies. This is likely due to the impact of prompt diagnosis, the improvement in therapies and care within a disease management structure. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Timing of Biochemical Failure and Distant Metastasis for Low, Intermediate, and High Risk Prostate Cancer after Radiotherapy

PubMed Central

Morgan, Peter B.; Hanlon, Alexandra L.; Horwitz, Eric M.; Buyyounouski, Mark K.; Uzzo, Robert G.; Pollack, Alan

2007-01-01

Condensed Abstract The timing of biochemical failure and distant metastasis after radiotherapy for low, intermediate and high-risk prostate cancer was determined. The patterns of failure suggest that the majority of early failures were due to subclinical micrometastases present at diagnosis, whereas a late wave of metastasis at 10–12 years in every risk group was consistent with tumor spread from local persistence of disease. Background The relationship of prostate cancer risk group stratification and the timing of biochemical failure (BF) and distant metastasis (DM) is not well defined. We sought to differentiate early failures due to subclinical micrometastasis at presentation from late failures due to local persistence. Methods A total of 1833 men with clinically localized prostate cancer treated with 3D-conformal radiotherapy with or without short-term androgen deprivation were retrospectively analyzed. The interval hazard rates of DM and BF, using ASTRO and Phoenix (Nadir+2) definitions, were determined for men with low, intermediate, and high risk disease. Results Median follow-up was 67 months. Multivariate analysis showed that increasing risk group was independently associated with higher ASTRO BF (P<.0001) and Nadir+2 BF (P<.0001). The preponderance (87%) of ASTRO BF occurred ≤4 years after RT, while Nadir+2 BF was more evenly spread over years 1–12, with 43% at >4 years. The hazard of Nadir+2 BF persisted in years 8–12 in all risk groups. The interval hazard function for DM appeared to be biphasic (early and late peaks) for intermediate and high risk patients, but no distinct early wave was evident for low risk patients. Conclusions ASTRO BF underestimates late BF due to backdating. Local persistence of disease is suggested by delayed Nadir+2 BF and subsequent late DM in every risk group. The paucity of early DM among those with low risk tumors supports the hypothesis that occult micrometastases contributed to the early wave. PMID:17520705

The role of shear and tensile failure in dynamically triggered landslides

USGS Publications Warehouse

Gipprich, T.L.; Snieder, R.K.; Jibson, R.W.; Kimman, W.

2008-01-01

Dynamic stresses generated by earthquakes can trigger landslides. Current methods of landslide analysis such as pseudo-static analysis and Newmark's method focus on the effects of earthquake accelerations on the landslide mass to characterize dynamic landslide behaviour. One limitation of these methods is their use Mohr-Coulomb failure criteria, which only accounts for shear failure, but the role of tensile failure is not accounted for. We develop a limit-equilibrium model to investigate the dynamic stresses generated by a given ground motion due to a plane wave and use this model to assess the role of shear and tensile failure in the initiation of slope instability. We do so by incorporating a modified Griffith failure envelope, which combines shear and tensile failure into a single criterion. Tests of dynamic stresses in both homogeneous and layered slopes demonstrate that two modes of failure exist, tensile failure in the uppermost meters of a slope and shear failure at greater depth. Further, we derive equations that express the dynamic stress in the near-surface in the acceleration measured at the surface. These equations are used to approximately define the depth range for each mechanism of failure. The depths at which these failure mechanisms occur suggest that shear and tensile failure might collaborate in generating slope failure. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

Precursory seismicity associated with frequent, large ice avalanches on Iliamna Volcano, Alaska, USA

USGS Publications Warehouse

Caplan-Auerbach, Jacqueline; Huggel, C.

2007-01-01

Since 1994, at least six major (volume>106 m3) ice and rock avalanches have occurred on Iliamna volcano, Alaska, USA. Each of the avalanches was preceded by up to 2 hours of seismicity believed to represent the initial stages of failure. Each seismic sequence begins with a series of repeating earthquakes thought to represent slip on an ice-rock interface, or between layers of ice. This stage is followed by a prolonged period of continuous ground-shaking that reflects constant slip accommodated by deformation at the glacier base. Finally the glacier fails in a large avalanche. Some of the events appear to have entrained large amounts of rock, while others comprise mostly snow and ice. Several avalanches initiated from the same source region, suggesting that this part of the volcano is particularly susceptible to failure, possibly due to the presence of nearby fumaroles. Although thermal conditions at the time of failure are not well constrained, it is likely that geothermal energy causes melting at the glacier base, promoting slip and culminating in failure. The frequent nature and predictable failure sequence of Iliamna avalanches makes the volcano an excellent laboratory for the study of ice avalanches. The prolonged nature of the seismic signal suggests that warning may one day be given for similar events occurring in populated regions.

Comparison of atazanavir/ritonavir and darunavir/ritonavir based antiretroviral therapy for antiretroviral naïve patients.

PubMed

Antoniou, Tony; Szadkowski, Leah; Walmsley, Sharon; Cooper, Curtis; Burchell, Ann N; Bayoumi, Ahmed M; Montaner, Julio S G; Loutfy, Mona; Klein, Marina B; Machouf, Nima; Tsoukas, Christos; Wong, Alexander; Hogg, Robert S; Raboud, Janet

2017-04-11

Atazanavir/ritonavir and darunavir/ritonavir are common protease inhibitor-based regimens for treating patients with HIV. Studies comparing these drugs in clinical practice are lacking. We conducted a retrospective cohort study of antiretroviral naïve participants in the Canadian Observational Cohort (CANOC) collaboration initiating atazanavir/ritonavir- or darunavir/ritonavir-based treatment. We used separate Fine and Gray competing risk regression models to compare times to regimen failure (composite of virologic failure or discontinuation for any reason). Additional endpoints included virologic failure, discontinuation due to virologic failure, discontinuation for other reasons, and virologic suppression. We studied 222 patients treated with darunavir/ritonavir and 1791 patients treated with atazanavir/ritonavir. Following multivariable adjustment, there was no difference between darunavir/ritonavir and atazanavir-ritonavir in the risk of regimen failure (adjusted hazard ratio 0.76, 95% CI 0.56 to 1.03) Darunavir/ritonavir-treated patients were at lower risk of virologic failure relative to atazanavir/ritonavir treated patients (aHR 0.50, 95% CI 0.28 to 0.91), findings driven largely by high rates of virologic failure among atazanavir/ritonavir-treated patients in the province of British Columbia. Of 108 discontinuations due to virologic failure, all occurred in patients starting atazanavir/ritonavir. There was no difference between regimens in time to discontinuation for reasons other than virologic failure (aHR 0.93; 95% CI 0.65 to 1.33) or virologic suppression (aHR 0.99, 95% CI 0.82 to 1.21). The risk of regimen failure was similar between patients treated with darunavir/ritonavir and atazanavir/ritonavir. Although darunavir/ritonavir was associated with a lower risk of virologic failure relative to atazanavir/ritonavir, this difference varied substantially by Canadian province and likely reflects regional variation in prescribing practices and patient characteristics.

[The Predictive Factors of Stent Failure in the Treatment of Malignant Extrinsc Ureteral Obstruction Using Internal Ureteral Stents].

PubMed

Matsuura, Hiroshi; Arase, Shigeki; Hori, Yasuhide; Tochigi, Hiromi

2017-12-01

In this study, we retrospectively reviewed the experiences at our single institute in the treatment of malignant extrinsic ureteral obstruction (MUO) using ureteral stents to investigate the clinical outcomes and the predictive factors of stent failure. In 52 ureters of 38 patients who had radiologically significant hydronephrosis due to MUO, internal ureteral stents (The BARD(R) INLAY(TM) ureteral stent set) were inserted. The median follow-up interval after the initial stent insertion was 124.5 days (4-1,120). Stent failure occurred in 8 ureters (15.4%) of the 7 patients. The median interval from the first stent insertion to stent failure was 88 days (1-468). A Cox regression multivariate analysis showed that the significant predictors of stent failure were bladder invasion. Based on the possibility of stent failure, the adaptation of the internal ureteral stent placement should be considered especially in a patient with MUO combined with bladder invasion.

A review of wiring system safety in space power systems

NASA Technical Reports Server (NTRS)

Stavnes, Mark W.; Hammoud, Ahmad N.

1993-01-01

Wiring system failures have resulted from arc propagation in the wiring harnesses of current aerospace vehicles. These failures occur when the insulation becomes conductive upon the initiation of an arc. In some cases, the conductive path of the carbon arc track displays a high enough resistance such that the current is limited, and therefore may be difficult to detect using conventional circuit protection. Often, such wiring failures are not simply the result of insulation failure, but are due to a combination of wiring system factors. Inadequate circuit protection, unforgiving system designs, and careless maintenance procedures can contribute to a wiring system failure. This paper approaches the problem with respect to the overall wiring system, in order to determine what steps can be taken to improve the reliability, maintainability, and safety of space power systems. Power system technologies, system designs, and maintenance procedures which have led to past wiring system failures will be discussed. New technologies, design processes, and management techniques which may lead to improved wiring system safety will be introduced.

Ultrasonic Spot Welding of a Rare-Earth Containing ZEK100 Magnesium Alloy: Effect of Welding Energy

NASA Astrophysics Data System (ADS)

Macwan, A.; Chen, D. L.

2016-04-01

Ultrasonic spot welding was used to join a low rare-earth containing ZEK100 Mg alloy at different levels of welding energy, and tensile lap shear tests were conducted to evaluate the failure strength in relation to the microstructural changes. It was observed that dynamic recrystallization occurred in the nugget zone; the grain size increased and microhardness decreased with increasing welding energy arising from the increasing interface temperature and strain rate. The weld interface experienced severe plastic deformation at a high strain rate from ~500 to ~2100 s-1 with increasing welding energy from 500 to 2000 J. A relationship between grain size and Zener-Hollomon parameter, and a Hall-Petch-type relationship between microhardness and grain size were established. The tensile lap shear strength and failure energy were observed to first increase with increasing welding energy, reach the maximum values at 1500 J, and then decrease with a further increase in the welding energy. The samples welded at a welding energy ≤1500 J exhibited an interfacial failure mode, while nugget pull-out occurred in the samples welded at a welding energy above 1500 J. The fracture surfaces showed typical shear failure. Low-temperature tests at 233 K (-40 °C) showed no significant effect on the strength and failure mode of joints welded at the optimal welding energy of 1500 J. Elevated temperature tests at 453 K (180 °C) revealed a lower failure load but a higher failure energy due to the increased deformability, and showed a mixed mode of partial interfacial failure and partial nugget pull-out.

The preparedness of hospital Health Information Services for system failures due to internal disasters.

PubMed

Lee, Cheens; Robinson, Kerin M; Wendt, Kate; Williamson, Dianne

The unimpeded functioning of hospital Health Information Services (HIS) is essential for patient care, clinical governance, organisational performance measurement, funding and research. In an investigation of hospital Health Information Services' preparedness for internal disasters, all hospitals in the state of Victoria with the following characteristics were surveyed: they have a Health Information Service/ Department; there is a Manager of the Health Information Service/Department; and their inpatient capacity is greater than 80 beds. Fifty percent of the respondents have experienced an internal disaster within the past decade, the majority affecting the Health Information Service. The most commonly occurring internal disasters were computer system failure and floods. Two-thirds of the hospitals have internal disaster plans; the most frequently occurring scenarios provided for are computer system failure, power failure and fire. More large hospitals have established back-up systems than medium- and small-size hospitals. Fifty-three percent of hospitals have a recovery plan for internal disasters. Hospitals typically self-rate as having a 'medium' level of internal disaster preparedness. Overall, large hospitals are better prepared for internal disasters than medium and small hospitals, and preparation for disruption of computer systems and medical record services is relatively high on their agendas.

Identification of Bearing Failure Using Signal Vibrations

NASA Astrophysics Data System (ADS)

Yani, Irsyadi; Resti, Yulia; Burlian, Firmansyah

2018-04-01

Vibration analysis can be used to identify damage to mechanical systems such as journal bearings. Identification of failure can be done by observing the resulting vibration spectrum by measuring the vibration signal occurring in a mechanical system Bearing is one of the engine elements commonly used in mechanical systems. The main purpose of this research is to monitor the bearing condition and to identify bearing failure on a mechanical system by observing the resulting vibration. Data collection techniques based on recordings of sound caused by the vibration of the mechanical system were used in this study, then created a database system based bearing failure due to vibration signal recording sounds on a mechanical system The next step is to group the bearing damage by type based on the databases obtained. The results show the percentage of success in identifying bearing damage is 98 %.

The role of tectonic damage and brittle rock fracture in the development of large rock slope failures

NASA Astrophysics Data System (ADS)

Brideau, Marc-André; Yan, Ming; Stead, Doug

2009-01-01

Rock slope failures are frequently controlled by a complex combination of discontinuities that facilitate kinematic release. These discontinuities are often associated with discrete folds, faults, and shear zones, and/or related tectonic damage. The authors, through detailed case studies, illustrate the importance of considering the influence of tectonic structures not only on three-dimensional kinematic release but also in the reduction of rock mass properties due to induced damage. The case studies selected reflect a wide range of rock mass conditions. In addition to active rock slope failures they include two major historic failures, the Hope Slide, which occurred in British Columbia in 1965 and the Randa rockslides which occurred in Switzerland in 1991. Detailed engineering geological mapping combined with rock testing, GIS data analysis and for selected case numerical modelling, have shown that specific rock slope failure mechanisms may be conveniently related to rock mass classifications such as the Geological Strength Index (GSI). The importance of brittle intact rock fracture in association with pre-existing rock mass damage is emphasized though a consideration of the processes involved in the progressive-time dependent development not only of though-going failure surfaces but also lateral and rear-release mechanisms. Preliminary modelling data are presented to illustrate the importance of intact rock fracture and step-path failure mechanisms; and the results are discussed with reference to selected field observations. The authors emphasize the importance of considering all forms of pre-existing rock mass damage when assessing potential or operative failure mechanisms. It is suggested that a rock slope rock mass damage assessment can provide an improved understanding of the potential failure mode, the likely hazard presented, and appropriate methods of both analysis and remedial treatment.

Modelling river bank erosion processes and mass failure mechanisms using 2-D depth averaged numerical model

NASA Astrophysics Data System (ADS)

Die Moran, Andres; El kadi Abderrezzak, Kamal; Tassi, Pablo; Herouvet, Jean-Michel

2014-05-01

Bank erosion is a key process that may cause a large number of economic and environmental problems (e.g. land loss, damage to structures and aquatic habitat). Stream bank erosion (toe erosion and mass failure) represents an important form of channel morphology changes and a significant source of sediment. With the advances made in computational techniques, two-dimensional (2-D) numerical models have become valuable tools for investigating flow and sediment transport in open channels at large temporal and spatial scales. However, the implementation of mass failure process in 2D numerical models is still a challenging task. In this paper, a simple, innovative algorithm is implemented in the Telemac-Mascaret modeling platform to handle bank failure: failure occurs whether the actual slope of one given bed element is higher than the internal friction angle. The unstable bed elements are rotated around an appropriate axis, ensuring mass conservation. Mass failure of a bank due to slope instability is applied at the end of each sediment transport evolution iteration, once the bed evolution due to bed load (and/or suspended load) has been computed, but before the global sediment mass balance is verified. This bank failure algorithm is successfully tested using two laboratory experimental cases. Then, bank failure in a 1:40 scale physical model of the Rhine River composed of non-uniform material is simulated. The main features of the bank erosion and failure are correctly reproduced in the numerical simulations, namely the mass wasting at the bank toe, followed by failure at the bank head, and subsequent transport of the mobilised material in an aggradation front. Volumes of eroded material obtained are of the same order of magnitude as the volumes measured during the laboratory tests.

Cognitive Awareness Prototype Development on User Interface Design

ERIC Educational Resources Information Center

Rosli, D'oria Islamiah

2015-01-01

Human error is a crucial problem in manufacturing industries. Due to the misinterpretation of information on interface system design, accidents or death may occur at workplace. Lack of human cognition criteria in interface system design is also one of the contributions to the failure in using the system effectively. Therefore, this paper describes…

49 CFR 230.22 - Accident reports.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Accident reports. 230.22 Section 230.22... Requirements § 230.22 Accident reports. In the case of an accident due to failure, from any cause, of a steam... persons, the railroad on whose line the accident occurred shall immediately make a telephone report of the...

49 CFR 230.22 - Accident reports.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Accident reports. 230.22 Section 230.22... Requirements § 230.22 Accident reports. In the case of an accident due to failure, from any cause, of a steam... persons, the railroad on whose line the accident occurred shall immediately make a telephone report of the...

7 CFR 457.133 - Prune crop insurance provisions.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Earthquake; (5) Volcanic eruption; (6) Failure of the irrigation water supply, if due to a cause specified in... fresh fruit. We will conduct an appraisal that will be used to determine your production to count for production that is sold by direct marketing or is sold as fresh fruit production. If damage occurs after this...

7 CFR 457.133 - Prune crop insurance provisions.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Earthquake; (5) Volcanic eruption; (6) Failure of the irrigation water supply, if due to a cause specified in... fresh fruit. We will conduct an appraisal that will be used to determine your production to count for production that is sold by direct marketing or is sold as fresh fruit production. If damage occurs after this...

76 FR 13539 - Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model ERJ 190 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-14

... de Aeronautica S.A. (EMBRAER) Model ERJ 190 Airplanes AGENCY: Federal Aviation Administration (FAA... the failure occurred due to hydrogen embrittlement. The ANAC [Ag[ecirc]ncia Nacional de Avia[ccedil.... For service information identified in this proposed AD, contact Empresa Brasileira de Aeronautica S.A...

Multisensor and Multispectral Approach in Documenting and Analyzing Liquefaction Hazard using Remote Sensing

NASA Astrophysics Data System (ADS)

Oommen, T.; Baise, L. G.; Gens, R.; Prakash, A.; Gupta, R. P.

2008-12-01

Seismic liquefaction is the loss of strength of soil due to shaking that leads to various ground failures such as lateral spreading, settlements, tilting, and sand boils. It is important to document these failures after earthquakes to advance our study of when and where liquefaction occurs. The current approach of mapping these failures by field investigation teams suffers due to the inaccessibility to some of the sites immediately after the event, short life of some of these failures, difficulties in mapping the aerial extent of the failure, incomplete coverage etc. After the 2001 Bhuj earthquake (India), researchers, using the Indian remote sensing satellite, illustrated that satellite remote sensing can provide a synoptic view of the terrain and offer unbiased estimates of liquefaction failures. However, a multisensor (data from different sensors onboard of the same or different satellites) and multispectral (data collected in different spectral regions) approach is needed to efficiently document liquefaction incidences and/or its potential of occurrence due to the possibility of a particular satellite being located inappropriately to image an area shortly after an earthquake. The use of SAR satellite imagery ensures the acquisition of data in all weather conditions at day and night as well as information complimentary to the optical data sets. In this study, we analyze the applicability of the various satellites (Landsat, RADARSAT, Terra-MISR, IRS-1C, IRS-1D) in mapping liquefaction failures after the 2001 Bhuj earthquake using Support Vector Data Description (SVDD). The SVDD is a kernel based nonparametric outlier detection algorithm inspired by the Support Vector Machines (SVMs), which is a new generation learning algorithm based on the statistical learning theory. We present the applicability of SVDD for unsupervised change-detection studies (i.e. to identify post-earthquake liquefaction failures). The liquefaction occurrences identified from the different satellites using SVDD have been compared to the ground truth in terms of documented liquefaction failures by other researchers. We present the applicability and appropriateness of the various satellites and spectral regions for documenting liquefaction related failures. Results illustrate that the SVDD is a promising unsupervised change-detection algorithm, which can help in automating the documentation of earthquake induced liquefaction failures.

Did a slump source cause the 1929 Grand Banks tsunami?

NASA Astrophysics Data System (ADS)

Løvholt, F.; Schulten, I.; Mosher, D.; Harbitz, C. B.; Krastel, S.

2017-12-01

On November 18, 1929, a Mw 7.2 earthquake occurred beneath the upper Laurentian Fan, south of Newfoundland. The earthquake displaced about 100 km3 of sediment volume that rapidly evolved into a turbidity current revealed by a series of successive telecommunication cable breaks. A tsunami with fatal consequences along the south coast of Newfoundland also resulted. This tsunami is attributed to sediment mass failure as no seafloor displacement due to the earthquake is observed or expected. Although sidescan sonar, sub-bottom profiler and modern multibeam data show surficial sediment slumping and translational slide activity in the upper part of the slope, no major headscarp, single evacuation area or large mass transport deposit are observed. Sediment mass failure has been interpreted as broadly distributed and shallow, likely occurring in a retrogressive fashion. The question remained, therefore, as to how such complex failure kinematics could generate a tsunami. The Grand Banks tsunami is the only landslide tsunami for which traces are found at transoceanic distances. Despite being a landmark event, only a couple of attempts to model the tsunami exist. None of these have been able to match tsunami observations. Recently acquired seismic reflection data suggest that rotational slumping of a thick sediment mass ( 500 m) on the St. Pierre Slope may have occurred, causing seafloor displacements (fault traces) up to 100 m in height. The previously mapped surficial failures were a consequence of slumping of the thicker mass. Here, we simulate tsunami generation using the new geophysical information to construct different tsunamigenic slump sources. In addition, we undertake simulations assuming a flowing surficial landslide. The numerical simulations shows that its large and rapid vertical displacements render the slump source more tsunamigenic than the alternative surficial landslide. The simulations using the slump source roughly complies with observations of large run-ups on the Burin Peninsula along the south coast of Newfoundland, in contrast to previous modelling attempts. As the source extensions complies with new observations of rotational failures at the slope, the simulations suggest that a slump source is the most likely explanation for the large tsunami observations due to the Grand Banks event.

The Study of the Relationship between Probabilistic Design and Axiomatic Design Methodology. Volume 3

NASA Technical Reports Server (NTRS)

Onwubiko, Chin-Yere; Onyebueke, Landon

1996-01-01

Structural failure is rarely a "sudden death" type of event, such sudden failures may occur only under abnormal loadings like bomb or gas explosions and very strong earthquakes. In most cases, structures fail due to damage accumulated under normal loadings such as wind loads, dead and live loads. The consequence of cumulative damage will affect the reliability of surviving components and finally causes collapse of the system. The cumulative damage effects on system reliability under time-invariant loadings are of practical interest in structural design and therefore will be investigated in this study. The scope of this study is, however, restricted to the consideration of damage accumulation as the increase in the number of failed components due to the violation of their strength limits.

Rotor fragment protection program: Statistics on aircraft gas turbine ngine rotor failures that occurred in U.S. commercial aviation during 1978

NASA Technical Reports Server (NTRS)

Delucia, R. A.; Salvino, J. T.

1981-01-01

This report presents statistical information relating to the number of gas turbine engine rotor failures which occurred in commercial aviation service use. The predominant failure involved blade fragments, 82.4 percent of which were contained. Although fewer rotor rim, disk, and seal failures occurred, 33.3%, 100% and 50% respectively were uncontained. Sixty-five percent of the 166 rotor failures occurred during the takeoff and climb stages of flight.

Investigation of rectangular concrete columns reinforced or prestressed with fiber reinforced polymer (FRP) bars or tendons

NASA Astrophysics Data System (ADS)

Choo, Ching Chiaw

Fiber reinforced polymer (FRP) composites have been increasingly used in concrete construction. This research focused on the behavior of concrete columns reinforced with FRP bars, or prestressed with FRP tendons. The methodology was based the ultimate strength approach where stress and strain compatibility conditions and material constitutive laws were applied. Axial strength-moment (P-M) interaction relations of reinforced or prestressed concrete columns with FRP, a linearly-elastic material, were examined. The analytical results identified the possibility of premature compression and/or brittle-tension failure occurring in FRP reinforced and prestressed concrete columns where sudden and explosive type failures were expected. These failures were related to the rupture of FRP rebars or tendons in compression and/or in tension prior to concrete reaching its ultimate strain and strength. The study also concluded that brittle-tension failure was more likely to occur due to the low ultimate tensile strain of FRP bars or tendons as compared to steel. In addition, the failures were more prevalent when long term effects such as creep and shrinkage of concrete, and creep rupture of FRP were considered. Barring FRP failure, concrete columns reinforced with FRP, in some instances, gained significant moment resistance. As expected the strength interaction of slender steel or FRP reinforced concrete columns were dependent more on column length rather than material differences between steel and FRP. Current ACI minimum reinforcement ratio for steel (rhomin) reinforced concrete columns may not be adequate for use in FRP reinforced concrete columns. Design aids were developed in this study to determine the minimum reinforcement ratio (rhof,min) required for rectangular reinforced concrete columns by averting brittle-tension failure to a failure controlled by concrete crushing which in nature was a less catastrophic and more gradual type failure. The proposed method using rhof,min enabled the analysis of FRP reinforced concrete columns to be carried out in a manner similar to steel reinforced concrete columns since similar provisions in ACI 318 were consistently used in developing these aids. The design aids produced accurate estimates of rhof,min. When creep and shrinkage effects of concrete were considered, conservative rhof,min values were obtained in order to preserve an adequate margin of safety due to their unpredictability.

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.

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

DiCostanzo, D; Ayan, A; Woollard, J

Purpose: To predict potential failures of hardware within the Varian TrueBeam linear accelerator in order to proactively replace parts and decrease machine downtime. Methods: Machine downtime is a problem for all radiation oncology departments and vendors. Most often it is the result of unexpected equipment failure, and increased due to lack of in-house clinical engineering support. Preventative maintenance attempts to assuage downtime, but often is ineffective at preemptively preventing many failure modes such as MLC motor failures, the need to tighten a gantry chain, or the replacement of a jaw motor, among other things. To attempt to alleviate downtime, softwaremore » was developed in house that determines the maximum value of each axis enumerated in the Truebeam trajectory log files. After patient treatments, this data is stored in a SQL database. Microsoft Power BI is used to plot the average maximum error of each day of each machine as a function of time. The results are then correlated with actual faults that occurred at the machine with the help of Varian service engineers. Results: Over the course of six months, 76,312 trajectory logs have been written into the database and plotted in Power BI. Throughout the course of analysis MLC motors have been replaced on three machines due to the early warning of the trajectory log analysis. The service engineers have also been alerted to possible gantry issues on one occasion due to the aforementioned analysis. Conclusion: Analyzing the trajectory log data is a viable and effective early warning system for potential failures of the TrueBeam linear accelerator. With further analysis and tightening of the tolerance values used to determine a possible imminent failure, it should be possible to pinpoint future issues more thoroughly and for more axes of motion.« less

Post-disaster victimization: how survivors of disasters can continue to suffer after the event is over.

PubMed

Phua, Kai-Lit

2008-01-01

When public health researchers study the health effects of disasters (whether "naturally-occurring," disasters due to failure of technology, or disasters due to terrorism), some aspects of the post-disaster situation of victims are often overlooked. Social science research has shown that the vast majority of people tend to behave altruistically during and after a disaster. Nevertheless, cases of victimization of survivors do occur. They can include post-disaster victimization of survivors by other individuals (including fellow survivors, opportunistic outsiders, and even unethical aid workers and rogue members of the police, armed forces or international organizations such as the United Nations), groups (such as organized criminal gangs) and institutions (through neglect, incompetence, bureaucratic inefficiency or through institutionalized discriminatory practices). In this article, various kinds of post-disaster victimization that can occur are discussed.

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.

Submarine landslides triggered by destabilization of high-saturation hydrate anomalies

NASA Astrophysics Data System (ADS)

Handwerger, Alexander L.; Rempel, Alan W.; Skarbek, Rob M.

2017-07-01

Submarine landslides occur along continental margins at depths that often intersect the gas hydrate stability zone, prompting suggestions that slope stability may be affected by perturbations that arise from changes in hydrate stability. Here we develop a numerical model to identify the conditions under which the destabilization of hydrates results in slope failure. Specifically, we focus on high-saturation hydrate anomalies at fine-grained to coarse-grained stratigraphic boundaries that can transmit bridging stresses that decrease the effective stress at sediment contacts and disrupt normal sediment consolidation. We evaluate slope stability before and after hydrate destabilization. Hydrate anomalies act to significantly increase the overall slope stability due to large increases in effective cohesion. However, when hydrate anomalies destabilize there is a loss of cohesion and increase in effective stress that causes the sediment grains to rapidly consolidate and generate pore pressures that can either trigger immediate slope failure or weaken the surrounding sediment until the pore pressure diffuses away. In cases where failure does not occur, the sediment can remain weakened for months. In cases where failure does occur, we quantify landslide dynamics using a rate and state frictional model and find that landslides can display either slow or dynamic (i.e., catastrophic) motion depending on the rate-dependent properties, size of the stress perturbation, and the size of the slip patch relative to a critical nucleation length scale. Our results illustrate the fundamental mechanisms through which the destabilization of gas hydrates can pose a significant geohazard.

National Transportation Safety Board Pipeline Special Investigation Report: Evaluation of Pipeline Failures During Flooding and of Spill Response Actions, San Jacinto River Near Houston Texas, October 1994

DOT National Transportation Integrated Search

1996-09-06

In mid-October 1994, major flooding occurred in the San Jacinto River flood plain near Houston, Texas. Due to the flooding, 8 pipelines ruptured and many others were undermined. Ignition of petroleum and petroleum products released into the river res...

Class and Home Problems. Modeling an Explosion: The Devil Is in the Details

ERIC Educational Resources Information Center

Hart, Peter W.; Rudie, Alan W.

2011-01-01

Within the past 15 years, three North American pulp mills experienced catastrophic equipment failures while using 50 wt% hydrogen peroxide. In two cases, explosions occurred when normal pulp flow was interrupted due to other process problems. To understand the accidents, a kinetic model of alkali-catalyzed decomposition of peroxide was developed.…

SVM-based tree-type neural networks as a critic in adaptive critic designs for control.

PubMed

Deb, Alok Kanti; Jayadeva; Gopal, Madan; Chandra, Suresh

2007-07-01

In this paper, we use the approach of adaptive critic design (ACD) for control, specifically, the action-dependent heuristic dynamic programming (ADHDP) method. A least squares support vector machine (SVM) regressor has been used for generating the control actions, while an SVM-based tree-type neural network (NN) is used as the critic. After a failure occurs, the critic and action are retrained in tandem using the failure data. Failure data is binary classification data, where the number of failure states are very few as compared to the number of no-failure states. The difficulty of conventional multilayer feedforward NNs in learning this type of classification data has been overcome by using the SVM-based tree-type NN, which due to its feature to add neurons to learn misclassified data, has the capability to learn any binary classification data without a priori choice of the number of neurons or the structure of the network. The capability of the trained controller to handle unforeseen situations is demonstrated.

Re‐estimated effects of deep episodic slip on the occurrence and probability of great earthquakes in Cascadia

USGS Publications Warehouse

Beeler, Nicholas M.; Roeloffs, Evelyn A.; McCausland, Wendy

2013-01-01

Mazzotti and Adams (2004) estimated that rapid deep slip during typically two week long episodes beneath northern Washington and southern British Columbia increases the probability of a great Cascadia earthquake by 30–100 times relative to the probability during the ∼58 weeks between slip events. Because the corresponding absolute probability remains very low at ∼0.03% per week, their conclusion is that though it is more likely that a great earthquake will occur during a rapid slip event than during other times, a great earthquake is unlikely to occur during any particular rapid slip event. This previous estimate used a failure model in which great earthquakes initiate instantaneously at a stress threshold. We refine the estimate, assuming a delayed failure model that is based on laboratory‐observed earthquake initiation. Laboratory tests show that failure of intact rock in shear and the onset of rapid slip on pre‐existing faults do not occur at a threshold stress. Instead, slip onset is gradual and shows a damped response to stress and loading rate changes. The characteristic time of failure depends on loading rate and effective normal stress. Using this model, the probability enhancement during the period of rapid slip in Cascadia is negligible (<10%) for effective normal stresses of 10 MPa or more and only increases by 1.5 times for an effective normal stress of 1 MPa. We present arguments that the hypocentral effective normal stress exceeds 1 MPa. In addition, the probability enhancement due to rapid slip extends into the interevent period. With this delayed failure model for effective normal stresses greater than or equal to 50 kPa, it is more likely that a great earthquake will occur between the periods of rapid deep slip than during them. Our conclusion is that great earthquake occurrence is not significantly enhanced by episodic deep slip events.

Treatment of Dialysis Catheter–Related Enterococcus Bacteremia With an Antibiotic Lock: A Quality Improvement Report

PubMed Central

Peterson, William J.; Maya, Ivan D.; Carlton, Donna; Estrada, Erin; Allon, Michael

2008-01-01

Background Catheter-related bacteremia (CRB) is a frequent complication of tunneled dialysis catheters, and Enterococcus is a common infecting organism. CRB may be treated by instilling an antibiotic lock into the catheter lumen, in conjunction with systemic antibiotics. The efficacy of this approach in Enterococcus bacteremia is unknown. Design Quality improvement report. Setting and participants 64 catheter-dependent hemodialysis outpatients with vancomycin-sensitive Enterococcus bacteremia treated with a uniform antibiotic lock protocol. Clinical outcomes were tracked prospectively. Quality improvement plans Patients received intravenous vancomycin for 3 weeks, in conjunction with a vancomycin lock instilled into both catheter lumens after each dialysis session. Measures Treatment failure was defined as persistent fever 48 hours after initiation of antibiotics or recurrent Enterococcus bacteremia within 90 days. A clinical cure was defined as fever resolution without recurrent bacteremia. Major infection-related complications within 6 months were documented. Results Treatment failure occurred in 25 patients (39%), due to persistent fever in 10, and recurrent bacteremia in 15. Treatment success occurred in 39 patients (61%). A serious complication of Enterococcus CRB occurred in 4 of 64 patients (6%), endocarditis in 1 and osteomyelitis in 3. The frequency of serious complications was 16% (4/25) in patients with treatment failure, as compared with 0% (0/39) in those with treatment success (P=0.01). Limitations This was a single-center study. We did not measure serum vancomycin levels. Conclusions An antibiotic lock protocol permits catheter salvage in 61% of hemodialysis patients with Enterococcus CRB. Serious complications occur in 6% of patients, and are more common in those with treatment failure. PMID:18848379

Progressive Derechos in the Presence of Closed Upper-level Subtropical Anticyclones

NASA Astrophysics Data System (ADS)

Guastini, C.; Bosart, L. F.

2013-12-01

Progressive derechos are a type of long-lived mesoscale convective system that produces large swaths of wind damage. In contrast to their serial derecho counterparts, which form in association with extratropical cyclones, progressive derechos often occur in the presence of benign synoptic conditions on the poleward side of closed upper-level subtropical anticyclones. Forecasters have been known to struggle predicting progressive derechos with any certainty due to the common lack of large-scale support for severe weather in regimes dominated by anticyclonic conditions. This study will classify a group of days on which there was a closed upper-level anticyclone over the United States and a progressive derecho did not occur and a group of days on which there was a closed upper-level anticyclone over the United States and a progressive derecho did occur, examine the synoptic environments of the two groups, and identify derecho null cases. By analyzing the null cases, derecho failure modes will be determined, which will help forecaster situational awareness and reveal the science behind the environmental conditions necessary for, and detrimental to, derecho development. This presentation will include climatologies of both derechos and closed upper-level anticyclones over the United States for June, July, and August of the years 1994-2013 (the modern radar era). The presentation will also include closed anticyclone-relative composites of both derecho cases and derecho null cases. The composites will elucidate which conditions are necessary for, and which are detrimental to, derecho development. The hypothesis is that derecho failure days occur due either to the lack of a triggering mechanism or other phenomena working against convective development such as a strong capping inversion or transverse ageostrophic circulations around an upper-level jet creating subsidence in an otherwise favorable environment. A representative case study will be included to highlight a common derecho failure mode.

Compress knee arthroplasty has 80% 10-year survivorship and novel forms of bone failure.

PubMed

Healey, John H; Morris, Carol D; Athanasian, Edward A; Boland, Patrick J

2013-03-01

Compliant, self-adjusting compression technology is a novel approach for durable prosthetic fixation of the knee. However, the long-term survival of these constructs is unknown. We therefore determined the survival of the Compress prosthesis (Biomet Inc, Warsaw, IN, USA) at 5 and 10 actuarial years and identified the failure modes for this form of prosthetic fixation. We retrospectively reviewed clinical and radiographic records for all 82 patients who underwent Compress knee arthroplasty from 1998 to 2008, as well as one patient who received the device elsewhere but was followed at our institution. Prosthesis survivorship and modes of failure were determined. Followup was for a minimum of 12 months or until implant removal (median, 43 months; range, 6-131 months); 28 patients were followed for more than 5 years. We found a survivorship of 85% at 5 years and 80% at 10 years. Eight patients required prosthetic revision after interface failure due to aseptic loosening alone (n = 3) or aseptic loosening with periprosthetic fracture (n = 5). Additionally, five periprosthetic bone failures occurred that did not require revision: three patients had periprosthetic bone failure without fixation compromise and two exhibited irregular prosthetic osteointegration patterns with concomitant fracture due to mechanical insufficiency. Compress prosthetic fixation after distal femoral tumor resection exhibits long-term survivorship. Implant failure was associated with patient nonadherence to the recommended weightbearing proscription or with bone necrosis and fracture. We conclude this is the most durable FDA-approved fixation method for distal femoral megaprostheses. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

[Delayed right hepatic artery haemorrhage after iatrogenic gallbladder by laparoscopic cholecystectomy that required a liver transplant due to acute liver failure: clinical case and review of the literature].

PubMed

Robles Campos, Ricardo; Marín Hernández, Caridad; Fernández Hernández, Juan Angel; Sanchez Bueno, Francisco; Ramirez Romero, Pablo; Pastor Perez, Patricia; Parrilla Paricio, Pascual

2011-12-01

Right hepatic artery (RHA) injury after laparoscopic cholecystectomy (LC) may go unnoticed clinically, but can sometimes cause necrosis of the right lobe. Exceptionally, when the necrosis spreads to segment IV, fulminant liver failure (FLF) may occur, and an urgent liver transplantation (LT) may be required. We provide a review of the literature on patients with indication for an LT due to vascular damage caused by bile duct injury following LC. The case reported herein is the fourth described in the specialized literature of LT due to RHA injury after LC and the second of FLF after RHA injury. LT due to RHA injury was performed in 3 of 13 patients reported in the literature: one LT was performed at 3 months due to FLF, after an extended right hepatectomy was performed, and the remaining two were performed due to secondary biliary cirrhosis. Our patient was transplanted due to FLF 15 days after the injury. RHA injury after LC may require LT due to FLF. Although exceptional, this possibility should be considered when there are RHA complications that may require occlusion. Copyright © 2011 AEC. Published by Elsevier Espana. All rights reserved.

Safe structures for future aircraft

NASA Technical Reports Server (NTRS)

Mccomb, H. G., Jr.

1983-01-01

The failure mechanisms, design lessons, and test equipment employed by NASA in establishing the airworthiness and crashworthiness of aircraft components for commercial applications are described. The composites test programs have progressed to medium primary structures such as stabilizers and a vertical fin. The failures encountered to date have been due to the nonyielding nature of composites, which do not diffuse loads like metals, and the presence of eccentricities, irregular shapes, stiffness changes, and discontinuities that cause tension and shear. Testing to failure, which always occurred in first tests before the design loads were reached, helped identify design changes and reinforcements that produced successful products. New materials and NDE techniques are identified, together with aircraft structural design changes that offer greater protection to the passengers, fuel antimisting agents, and landing gear systems.

Correlation of electrical reactor cable failure with materials degradation

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

Stuetzer, O.M.

1986-03-01

Complete circuit failure (shortout) of electrical cables typically used in nuclear power plant containments is investigated. Failure modes are correlated with the mechanical deterioration of the elastomeric cable materials. It is found that for normal reactor operation, electrical cables are reliable and safe over very long periods. During high temperature excursions, however, cables pulled across corners under high stress may short out due to conductor creep. Severe cracking will occur in short times during high temperatures (>150/sup 0/C) and in times of the order of years at elevated temperatures (100/sup 0/C to 140/sup 0/C). A theoretical treatment of stress distributionmore » responsible for creep and for cracking by J.E. Reaugh of Science Applications, Inc. is contained in the Appendix. 29 refs., 32 figs.« less

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).

Probabilistic modelling of overflow, surcharge and flooding in urban drainage using the first-order reliability method and parameterization of local rain series.

PubMed

Thorndahl, S; Willems, P

2008-01-01

Failure of urban drainage systems may occur due to surcharge or flooding at specific manholes in the system, or due to overflows from combined sewer systems to receiving waters. To quantify the probability or return period of failure, standard approaches make use of the simulation of design storms or long historical rainfall series in a hydrodynamic model of the urban drainage system. In this paper, an alternative probabilistic method is investigated: the first-order reliability method (FORM). To apply this method, a long rainfall time series was divided in rainstorms (rain events), and each rainstorm conceptualized to a synthetic rainfall hyetograph by a Gaussian shape with the parameters rainstorm depth, duration and peak intensity. Probability distributions were calibrated for these three parameters and used on the basis of the failure probability estimation, together with a hydrodynamic simulation model to determine the failure conditions for each set of parameters. The method takes into account the uncertainties involved in the rainstorm parameterization. Comparison is made between the failure probability results of the FORM method, the standard method using long-term simulations and alternative methods based on random sampling (Monte Carlo direct sampling and importance sampling). It is concluded that without crucial influence on the modelling accuracy, the FORM is very applicable as an alternative to traditional long-term simulations of urban drainage systems.

Successful treatment of inverted Takotsubo cardiomyopathy after severe traumatic brain injury with milrinone after dobutamine failure.

PubMed

Mrozek, Ségolène; Srairi, Mohamed; Marhar, Fouad; Delmas, Clément; Gaussiat, François; Abaziou, Timothée; Larcher, Claire; Atthar, Vincent; Menut, Rémi; Fourcade, Olivier; Geeraerts, Thomas

2016-01-01

Takotsubo cardiomyopathy can occur at the early phase of severe acute brain injuries. In the case of cardiac output decrease or shock, the optimal treatment is still a matter of debate. Due to massive stress hormone release, the infusion of catecholamines may have limited effects and may even aggravate cardiac failure. Other inotropic agents may be an option. Levosimendan has been shown to have potential beneficial effects in this setting, although milrinone has not been studied. We report a case of a young female presenting with inverted Takotsubo cardiomyopathy syndrome after severe traumatic brain injury. Due to hemodynamic instability and increasing levels of infused norepinephrine, dobutamine infusion was begun but rapidly stopped due to tachyarrhythmia. Milrinone infusion stabilized the patient's hemodynamic status and improved cardiac output without deleterious effects. Milrinone could be a good alternative when inotropes are required in Takotsubo cardiomyopathy and when dobutamine infusion is associated with tachyarrhythmia. Copyright © 2016 Elsevier Inc. All rights reserved.

Large Deformation Characteristics and Reinforcement Measures for a Rock Pillar in the Houziyan Underground Powerhouse

NASA Astrophysics Data System (ADS)

Xiao, Xin-hong; Xiao, Pei-wei; Dai, Feng; Li, Hai-bo; Zhang, Xue-bin; Zhou, Jia-wen

2018-02-01

The underground powerhouse of the Houziyan Hydropower Station is under the conditions of high geo-stress and a low strength/stress ratio, which leads to significant rock deformation and failures, especially for rock pillars due to bidirectional unloading during the excavation process. Damages occurred in thinner rock pillars after excavation due to unloading and stress concentration, which will reduce the surrounding rock integrity and threaten the safety of the underground powerhouse. By using field investigations and multi-source monitoring data, the deformation and failure characteristics of a rock pillar are analyzed from the tempo-spatial distribution features. These results indicate that significant deformation occurred in the rock pillar when the powerhouse was excavated to the fourth layer, and the maximum displacement reached 107.57 mm, which occurred on the main transformer chamber upstream sidewall at an elevation of 1721.20 m. The rock deformation surrounding the rock pillar is closely related to the excavation process and has significant time-related characteristics. To control large deformation of the rock pillar, thru-anchor cables were used to reinforce the rock pillar to ensure the stability of the powerhouse. The rock deformation surrounding the rock pillar decreases gradually and forms a convergent trend after reinforcement measures are installed based on the analysis of the temporal characteristics and the rock pillar deformation rate.

Observation of Failure and Domain Switching in Lead Zirconate Titanate Ceramics

NASA Astrophysics Data System (ADS)

Okayasu, Mitsuhiro; Sugiyama, Eriko; Sato, Kazuto; Mizuno, Mamoru

The mechanical and electrical properties (electromechanical coupling coefficient, piezoelectric constant and dielectric constant) of lead zirconate titanate (PZT) ceramics are investigated during mechanical static and cyclic loading. There are several failure characteristics which can alter the material properties of PZT ceramics. The elastic constant increases and electrical properties decrease with increasing the applied load. This is due to the internal strain arising from the domain switching. In this case, 90° domain switching occurs anywhere in the samples as the sample is loaded. It is also apparent that electrogenesis occurs several times during cyclic loading to the final fracture. This occurrence is related to the domain switching. The elastic constant and electrical properties can decrease because of crack generation in the PZT ceramics. Moreover, the elastic constant increases with increase of the mechanical load and decreases with decrease of the load. On the contrary, the opposite sense of change of the electrical properties is observed.

The SPS interference problem-electronic system effects and mitigation techniques

NASA Technical Reports Server (NTRS)

Juroshek, J. R.

1980-01-01

The potential for interference between solar power satellites (SPS) and other Earth satellite operations was examined along with interference problems involving specific electronic devices. Conclusions indicate that interference is likely in the 2500 MHz to 2690 MHz direct broadcast satellite band adjacent to SPS. Estimates of the adjacent channel noise from SPS in this band are as high as -124 dBc/4 kHz and -100 dBc/MHz, where dBc represents decibels relative to the total power in the fundamental. A second potential problem is the 7350 MHz, 3d harmonic from SPS that falls within the 7300 MHz to 7450 MHz space to Earth, government, satellite assignment. Catastrophic failures can be produced in integrated circuits when the microwave power levels coupled into inputs and power leads reach 1 to 100 watts. The failures are typically due to bonding wire melting, metallization failures, and junction shorting. Nondestructive interaction or interference, however, generally occurs with coupled power levels of the order of 10 milliwatts. This integration is due to the rectification of microwave energy by the numerous pn junctions within these circuits.

The Cassini project: Lessons learned through operations

NASA Astrophysics Data System (ADS)

McCormick, Egan D.

1998-01-01

The Cassini space probe requires 180 238Pu Light-weight Radioisotopic Heater Units (LWRHU) and 216 238Pu General Purpose Heat Source (GPHS) pellets. Additional LWRHU and GPHS pellets required for non-destructive (NDA) and destructive assay purposes were fabricated bringing the original pellet requirement to 224 LWRHU and 252 GPHS. Due to rejection of pellets resulting from chemical impurities in the fuel and/or failure to meet dimensional specifications a total of 320 GPHS pellets were fabricated for the mission. Initial plans called for LANL to process a total of 30 kg of oxide powder for pressing into monolithic ceramic pellets. The original 30 kg commitment was processed within the time frame allotted; an additional 8 kg were required to replace fuel lost due to failure to meet Quality Assurance specifications for impurities and dimensions. During the time frame allotted for pellet production, operations were impacted by equipment failure, unacceptable fuel impurities levels, and periods of extended down time, >30 working days during which little or no processing occurred. Throughout the production process, the reality of operations requirements varied from the theory upon which production schedules were based.

Testing and Failure Mechanisms of Ice Phase Change Material Heat Exchangers

NASA Technical Reports Server (NTRS)

Leimkuehler, Thomas O.; Stephan, Ryan A.; Hawkins-Reynolds, Ebony

2010-01-01

Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as Low Earth Orbit (LEO) and Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents the results of testing that occurred from March through September of 2010 and builds on testing that occurred during the previous year.

Testing and Failure Mechanisms of Ice Phase Change Material Heat Exchangers

NASA Technical Reports Server (NTRS)

Leimkuehler, Thomas O.; Stephan, Ryan A.; Hawkins-Reynolds, Ebony

2011-01-01

Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as specific spacecraft orientations in Low Earth Orbit (LEO) and low beta angle Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents the results of testing that occurred from March through September of 2010 and builds on testing that occurred during the previous year.

Porosity determination from 2-D resistivity method in studying the slope failures

NASA Astrophysics Data System (ADS)

Maslinda, Umi; Nordiana, M. M.; Bery, A. A.

2017-07-01

Slope failures have become the main focus for infrastructures development on hilly areas in Malaysia especially the development of tourism and residential. Lack of understanding and information of the subsoil conditions and geotechnical issues are the main cause of the slope failures. The failures happened are due to a combination of few factors such as topography, climate, geology and land use. 2-D resistivity method was conducted at the collapsed area in Selangor. The 2-D resistivity was done to study the instability of the area. The collapsed occurred because of the subsurface materials was unstable. Pole-dipole array was used with 5 m minimum electrode spacing for the 2-D resistivity method. The data was processed using Res2Dinv software and the porosity was calculated using Archie's law equation. The results show that the saturated zone (1-100 Ωm), alluvium or highly weathered rock (100-1000 Ωm), boulders (1600-7000 Ωm) and granitic bedrock (>7000 Ωm). Generally, the slope failures or landslides occur during the wet season or after rainfall. It is because of the water infiltrate to the slope and cause the saturation of the slope which can lead to landslides. Then, the porosity of saturated zone is usually high because of the water content. The area of alluvium or highly weathered rock and saturated zone have high porosity (>20%) and the high porosity also dominated at almost all the collapsed area which means that the materials with porosity >20% is potential to be saturated, unstable and might trigger slope failures.

Acoustic Emission Analysis of Prestressed Concrete Structures

NASA Astrophysics Data System (ADS)

Elfergani, H. A.; Pullin, R.; Holford, K. M.

2011-07-01

Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.

Continuous positive airway pressure with helmet versus mask in infants with bronchiolitis: an RCT.

PubMed

Chidini, Giovanna; Piastra, Marco; Marchesi, Tiziana; De Luca, Daniele; Napolitano, Luisa; Salvo, Ida; Wolfler, Andrea; Pelosi, Paolo; Damasco, Mirco; Conti, Giorgio; Calderini, Edoardo

2015-04-01

Noninvasive continuous positive airway pressure (CPAP) is usually applied with a nasal or facial mask to treat mild acute respiratory failure (ARF) in infants. A pediatric helmet has now been introduced in clinical practice to deliver CPAP. This study compared treatment failure rates during CPAP delivered by helmet or facial mask in infants with respiratory syncytial virus-induced ARF. In this multicenter randomized controlled trial, 30 infants with respiratory syncytial virus-induced ARF were randomized to receive CPAP by helmet (n = 17) or facial mask (n = 13). The primary endpoint was treatment failure rate (defined as due to intolerance or need for intubation). Secondary outcomes were CPAP application time, number of patients requiring sedation, and complications with each interface. Compared with the facial mask, CPAP by helmet had a lower treatment failure rate due to intolerance (3/17 [17%] vs 7/13 [54%], P = .009), and fewer infants required sedation (6/17 [35%] vs 13/13 [100%], P = .023); the intubation rates were similar. In successfully treated patients, CPAP resulted in better gas exchange and breathing pattern with both interfaces. No major complications due to the interfaces occurred, but CPAP by mask had higher rates of cutaneous sores and leaks. These findings confirm that CPAP delivered by helmet is better tolerated than CPAP delivered by facial mask and requires less sedation. In addition, it is safe to use and free from adverse events, even in a prolonged clinical setting. Copyright © 2015 by the American Academy of Pediatrics.

Characteristics of Volcanic Soils in Landslide during the 2016 Kumamoto Earthquake, Japan

NASA Astrophysics Data System (ADS)

Hazarika, H.; Fukuoka, H.; Kokusho, T.; Sumartini, O.; Bhoopendra, D.

2017-12-01

There were many seismic subsidence, debris flows, landslides and slope failures, which occurred in Aso area due to the 2016 Kumamoto earthquake, Japan. This research aims to determine the failure mechanism of many mild slopes, and elucidate the strength characteristics of volcanic soils collected from the sites. A series of undrained static and cyclic triaxial tests, ring shear tests and direct shear tests were performed. Also, for further understanding of volcanic soils' material strength, X-ray powder diffraction analysis (XRD), X-ray fluorescence analysis (XRF), and Scanning electron microscope analysis (SEM) were performed. In this paper, preliminary results of the experimental testing program are discussed.

[A case of fat embolism syndrome associated with pathological femoral fracture caused by metastatic adenocarcinoma of the lung].

PubMed

Sato, Takashi; Soejima, Kenzo; Nakayama, Sohei; Satomi, Ryosuke; Sayama, Koichi; Asano, Koichiro

2010-10-01

A 76-year-old woman with multiple bone metastases from lung adenocarcinoma was admitted due to a pathological femoral fracture. On the night after admission, her consciousness deteriorated rapidly and she developed progressive respiratory failure. Computed tomography of the chest revealed diffuse ground glass opacities in both lungs, and magnetic resonance imaging of the brain showed multiple acute infarctions. Her condition improved after several days of supportive treatment with oxygen, corticosteroids and diuretics. Fat embolism syndrome should be considered as a differential diagnosis if consciousness disturbance and respiratory failure occur in patients with metastatic bone carcinoma and pathological long bone fractures.

Diagnosis of renal disease in rabbits.

PubMed

Harcourt-Brown, Frances Margaret

2013-01-01

There are differences in renal anatomy and physiology between rabbits and other domestic species. Neurogenic renal ischemia occurs readily. Reversible prerenal azotemia may be seen in conjunction with gut stasis. Potentially fatal acute renal failure may be due to structural kidney damage or post-renal disease. Chronic renal failure is often associated with encephalitozoonosis. Affected rabbits cannot vomit and often eat well. Weight loss, lethargy, and cachexia are common clinical signs. Polydypsia/polyuria may be present. Derangements in calcium and phosphorus metabolism are features of renal disease. Radiography is always indicated. Urolithiasis, osteosclerosis, aortic and renal calcification are easily seen on radiographs. Copyright © 2013 Elsevier Inc. All rights reserved.

Severe tricuspid regurgitation in the aged: atrial remodeling associated with long-standing atrial fibrillation.

PubMed

Yamasaki, Naohito; Kondo, Fumiaki; Kubo, Toru; Okawa, Makoto; Matsumura, Yoshihisa; Kitaoka, Hiroaki; Yabe, Toshikazu; Furuno, Takashi; Doi, Yoshinori

2006-12-01

Severe idiopathic tricuspid regurgitation (TR) occurs in the aged, but the mechanism of TR is unclear and there is little information on atrial abnormalities associated with this condition. This study retrospectively analyzed patients with severe functional TR presenting with common clinical features suggesting a distinct syndrome. Eleven patients with severe functional TR were identified by reviewing the records of 16,235 consecutive patients. All patients had undergone clinical evaluation including echocardiography, electrocardiography and laboratory data. The median age of patients with severe functional TR was 78 years. All had a long-standing history of atrial fibrillation (median duration, 23 years). Clinical features are characterized by severe functional TR due to annular dilation, markedly dilated right atrium, episodes of right-sided heart failure, absent or diminished fibrillation waves on electrocardiogram, bradycardia probably due to partial atrial standstill, and decreased atrial natriuretic peptide secretion. During long-term follow up, right atrial size progressively increased in association with worsening TR. Severe functional TR occurs with long-standing atrial fibrillation and causes right-sided heart failure. The TR is caused by tricuspid valve systolic coaptation loss due to tricuspid annular dilation associated with atrial dilation. This condition is associated with atrial abnormalities, such as atrial standstill and impaired atrial natriuretic peptide secretion. We propose that atrial remodeling associated with atrial fibrillation is central to the occurrence of the syndrome.

Graphical Displays Assist In Analysis Of Failures

NASA Technical Reports Server (NTRS)

Pack, Ginger; Wadsworth, David; Razavipour, Reza

1995-01-01

Failure Environment Analysis Tool (FEAT) computer program enables people to see and better understand effects of failures in system. Uses digraph models to determine what will happen to system if set of failure events occurs and to identify possible causes of selected set of failures. Digraphs or engineering schematics used. Also used in operations to help identify causes of failures after they occur. Written in C language.

A servo-controlled canine model of stable severe ischemic left ventricular failure.

PubMed

Wagner, Richard L; Hood, William B; Howland, Peter A

2009-12-01

Reversible left ventricular failure was produced in conscious dogs by compromise of the coronary circulation. In animals with prior left anterior descending coronary artery occlusion, mean left atrial pressure (LAP) was incorporated into an automatic feedback control system used to inflate a balloon cuff on the circumflex (Cfx) coronary artery. The system could produce stable increases in LAP to 15-20 mm Hg. The dominating system transfer function was the ratio of LAP to balloon volume (BV), which was characterized by a fixed delay (5 s), with LAP/BV = (8e(-jomegatau ))/(0.02 + jomega). The system was stabilized by a phase lead network to reduce oscillations of LAP. A total of seven experiments were conducted in three dogs, and testing of inotropic agents was possible in three experiments under stable conditions with the pump off after an hour or more of operation. Problems encountered were 0.003-0.008 Hz oscillations in LAP in three experiments, which could usually be controlled by reducing the system gain. Late stage ventricular fibrillation occurred in all three animals, but defibrillation was easily accomplished after deflating the Cfx balloon. This system produces reversible left ventricular failure solely due to ischemia, thus closely simulating clinical heart failure due to coronary insufficiency.

AGR-5/6/7 Irradiation Test Predictions using PARFUME

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

Skerjanc, William F.

PARFUME, (PARticle FUel ModEl) a fuel performance modeling code used for high temperature gas-cooled reactors (HTGRs), was used to model the Advanced Gas Reactor (AGR)-5/6/7 irradiation test using predicted physics and thermal hydraulics data. The AGR-5/6/7 test consists of the combined fifth, sixth, and seventh planned irradiations of the AGR Fuel Development and Qualification Program. The AGR-5/6/7 test train is a multi-capsule, instrumented experiment that is designed for irradiation in the 133.4-mm diameter north east flux trap (NEFT) position of Advanced Test Reactor (ATR). Each capsule contains compacts filled with uranium oxycarbide (UCO) unaltered fuel particles. This report documents themore » calculations performed to predict the failure probability of tristructural isotropic (TRISO)-coated fuel particles during the AGR-5/6/7 experiment. In addition, this report documents the calculated source term from the driver fuel. The calculations include modeling of the AGR-5/6/7 irradiation that is scheduled to occur from October 2017 to April 2021 over a total of 13 ATR cycles, including nine normal cycles and four Power Axial Locator Mechanism (PALM) cycle for a total between 500 – 550 effective full power days (EFPD). The irradiation conditions and material properties of the AGR-5/6/7 test predicted zero fuel particle failures in Capsules 1, 2, and 4. Fuel particle failures were predicted in Capsule 3 due to internal particle pressure. These failures were predicted in the highest temperature compacts. Capsule 5 fuel particle failures were due to inner pyrolytic carbon (IPyC) cracking causing localized stresses concentrations in the SiC layer. This capsule predicted the highest particle failures due to the lower irradiation temperature. In addition, shrinkage of the buffer and IPyC layer during irradiation resulted in formation of a buffer-IPyC gap. The two capsules at the two ends of the test train, Capsules 1 and 5 experienced the smallest buffer-IPyC gap formation due to the lower irradiation fluences and temperatures. Capsule 3 experienced the largest buffer-IPyC gap formation of just under 24 µm. The release fraction of fission products Ag, Cs, and Sr silver (Ag), cesium (Cs), and strontium (Sr) vary depending on capsule location and irradiation temperature. The maximum release fraction of Ag occurs in Capsule 3, reaching up to 84.8% for the TRISO fuel particles. The release fraction of the other two fission products, Cs and Sr are much smaller and, in most cases, less than 1%. The notable exception is again in Capsule 3, where the release fraction for Cs and Sr reach up to 9.7% and 19.1%, respectively.« less

Sudden Bilateral Sensorineural Hearing Loss Following Postpartum Hemorrhage: A Case Report

PubMed Central

Mirzaeian, Sara; Ayati, Sedigheh; Maleki, Asieh

2017-01-01

The prevalence of bilateral sudden sensorineural hearing loss (SSNHL) is less than 5% and the etiology of most cases is unknown. Due to many structural and functional similarities between the kidney and inner ear, many conditions, diseases, and drugs have both renal and cochlear effects and toxicities. There are several reports of SSNHL in patients with CRF, uraemic patient, hemodialysis treatment, and ARF. Here, we report a rare manifestation of SSNHL following severe postpartum hemorrhage that has simultaneous renal failure and cochlear impairment. The patient was a 22-year-old primigravida woman with term pregnancy who after delivery and episiotomy hematoma and postpartum hemorrhage subsequently suffered from kidney failure, oliguria, and SSNHL that occurred after 3 days of delivery. In conditions such as severe postpartum bleeding leading to acute renal involvement, the possibility of simultaneous involvement of cochlea due to hypoxia or received drugs should be considered. PMID:28761208

Analysis and reduction of well failures in diatomite reservoirs

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

Meyer, L.; Jacobsen, J.; Horsman, J.

1995-12-31

Well damage induced by compactable formation deformation has occurred in oil fields in the Gulf of Mexico, the mid-continent region, the North Sea, on-shore Europe, Asia, and South America. The diatomite reservoirs of California are particularly susceptible to compaction due to the very high porosity of the diatomite. In these reservoirs well replacement, lost production and abandonment costs have exceeded $200 million to date. In 1994 alone about 40 wells were damaged. A study is currently underway involving data analysis and 3-D visualization, laboratory testing, and numerical modelling to improve understanding of casing damage due to reservoir compaction and tomore » develop tools and operating strategies to reduce casing damage. The study is focused on the South Belridge field. Results to date show a consistent correlation between failure and structural markers and apparent influence of local production and injection supporting the need for 3-D simulation.« less

Heroic Measures for an American Hero: Attempting to Save the Life of General Douglas MacArthur.

PubMed

Pappas, Theodore N

2017-12-01

General Douglas MacArthur was a towering public figure on an international stage for the first half of the 20th century. He was healthy throughout his life but developed a series of medical problems when he entered his 80s. This article reviews the General's medical care during two separate life-threatening medical crises that required surgical intervention. The first episode occurred in 1960 when MacArthur presented with renal failure due to an obstructed prostate. Four years later after his 84th birthday, MacArthur developed bile duct obstruction from common duct stones. He underwent an uncomplicated cholecystectomy and common duct exploration but developed variceal bleeding requiring an emergent splenorenal shunt. His terminal event was precipitated by strangulated bowel in long-ignored very large inguinal hernias. MacArthur died, despite state-of-the-art surgical intervention, due to renal failure and hepatic coma.

Modelling of catastrophic flashing releases.

PubMed

Deaves, D M; Gilham, S; Mitchell, B H; Woodburn, P; Shepherd, A M

2001-11-16

Several low boiling point materials are stored in closed vessels at ambient temperature, using their own vapour pressure to maintain a liquid state. These materials are often toxic, flammable, or both, and thus any uncontrolled release can have potentially disastrous consequences. There are many ways in which an accidental release can occur, the most severe being due to catastrophic vessel failure. Although not the most common, this mode of failure has the potential to result in an instantaneous loss of the entire vessel inventory in the form of a rapidly expanding, two-phase, vaporising cloud. This paper provides a comprehensive review of the physical processes of existing models and of available experimental and incident data to model such scenarios. Subsequently, this has enabled the development of an improved methodology for the characterisation of the source conditions following catastrophic vessel failures.

Helium vs. Proton Induced Displacement Damage in Electronic Materials

NASA Technical Reports Server (NTRS)

Ringo, Sawnese; Barghouty, A. F.

2010-01-01

In this project, the specific effects of displacement damage due to the passage of protons and helium nuclei on some typical electronic materials will be evaluated and contrasted. As the electronic material absorbs the energetic proton and helium momentum, degradation of performance occurs, eventually leading to overall failure. Helium nuclei traveling at the same speed as protons are expected to impart more to the material displacement damage; due to the larger mass, and thus momentum, of helium nuclei compared to protons. Damage due to displacement of atoms in their crystalline structure can change the physical properties and hence performance of the electronic materials.

Reliability Effects of Surge Current Testing of Solid Tantalum Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander

2007-01-01

Solid tantalum capacitors are widely used in space applications to filter low-frequency ripple currents in power supply circuits and stabilize DC voltages in the system. Tantalum capacitors manufactured per military specifications (MIL-PRF-55365) are established reliability components and have less than 0.001% of failures per 1000 hours (the failure rate is less than 10 FIT) for grades D or S, thus positioning these parts among electronic components with the highest reliability characteristics. Still, failures of tantalum capacitors do happen and when it occurs it might have catastrophic consequences for the system. This is due to a short-circuit failure mode, which might be damaging to a power supply, and also to the capability of tantalum capacitors with manganese cathodes to self-ignite when a failure occurs in low-impedance applications. During such a failure, a substantial amount of energy is released by exothermic reaction of the tantalum pellet with oxygen generated by the overheated manganese oxide cathode, resulting not only in destruction of the part, but also in damage of the board and surrounding components. A specific feature of tantalum capacitors, compared to ceramic parts, is a relatively large value of capacitance, which in contemporary low-size chip capacitors reaches dozens and hundreds of microfarads. This might result in so-called surge current or turn-on failures in the parts when the board is first powered up. Such a failure, which is considered as the most prevalent type of failures in tantalum capacitors [I], is due to fast changes of the voltage in the circuit, dV/dt, producing high surge current spikes, I(sub sp) = Cx(dV/dt), when current in the circuit is unrestricted. These spikes can reach hundreds of amperes and cause catastrophic failures in the system. The mechanism of surge current failures has not been understood completely yet, and different hypotheses were discussed in relevant literature. These include a sustained scintillation breakdown model [1-3]; electrical oscillations in circuits with a relatively high inductance [4-6]; local overheating of the cathode [5,7, 8]; mechanical damage to tantalum pentoxide dielectric caused by the impact of MnO2 crystals [2,9, 10]; or stress-induced-generation of electron traps caused by electromagnetic forces developed during current spikes [11]. A commonly accepted explanation of the surge current failures is that at unlimited current supply during surge current conditions, the self-healing mechanism in tantalum capacitors does not work, and what would be a minor scintillation spike if the current were limited, becomes a catastrophic failure of the part [l, 12]. However, our data show that the scintillation breakdown voltages are significantly greater that the surge current breakdown voltages, so it is still not clear why the part, which has no scintillations, would fail at the same voltage during surge current testing (SCT).

Compression failure mechanisms of composite structures

NASA Technical Reports Server (NTRS)

Hahn, H. T.; Sohi, M.; Moon, S.

1986-01-01

An experimental and analytical study was conducted to delineate the compression failure mechanisms of composite structures. The present report summarizes further results on kink band formation in unidirectional composites. In order to assess the compressive strengths and failure modes of fibers them selves, a fiber bundle was embedded in epoxy casting and tested in compression. A total of six different fibers were used together with two resins of different stiffnesses. The failure of highly anisotropic fibers such as Kevlar 49 and P-75 graphite was due to kinking of fibrils. However, the remaining fibers--T300 and T700 graphite, E-glass, and alumina--failed by localized microbuckling. Compressive strengths of the latter group of fibers were not fully utilized in their respective composite. In addition, acoustic emission monitoring revealed that fiber-matrix debonding did not occur gradually but suddenly at final failure. The kink band formation in unidirectional composites under compression was studied analytically and through microscopy. The material combinations selected include seven graphite/epoxy composites, two graphite/thermoplastic resin composites, one Kevlar 49/epoxy composite and one S-glass/epoxy composite.

Fatigue of the Resin-Enamel Bonded Interface and the Mechanisms of Failure

PubMed Central

Yahyazadehfar, Mobin; Mutluay, Mustafa Murat; Majd, Hessam; Ryou, Heonjune; Arola, Dwayne

2013-01-01

The durability of adhesive bonds to enamel and dentin and the mechanisms of degradation caused by cyclic loading are important to the survival of composite restorations. In this study a novel method of evaluation was used to determine the strength of resin-enamel bonded interfaces under both static and cyclic loading, and to identify the mechanisms of failure. Specimens with twin interfaces of enamel bonded to commercial resin composite were loaded in monotonic and cyclic 4-point flexure to failure within a hydrated environment. Results for the resin-enamel interface were compared with those for the resin composite (control) and values reported for resin-dentin adhesive bonds. Under both modes of loading the strength of the resin-enamel interface was significantly (p≤0.0001) lower than that of the resin composite and the resin-dentin bonded interface. Fatigue failure of the interface occurred predominately by fracture of enamel, adjacent to the interface, and not due to adhesive failures. In the absence of water aging or acid production of biofilms, the durability of adhesive bonds to enamel is lower than that achieved in dentin bonding. PMID:23571321

Self-Efficacy in Situation Background Assessment and Recommendation Communication Using Information Technology in Baccalaureate Nursing

ERIC Educational Resources Information Center

Espinoza, Kelly Etcheberry

2016-01-01

Strong communication skills are essential in establishing a foundation for safe delivery of care. A report from the Institute of Medicine (IOM) titled: "To Err is Human: Building a Safer Health System" estimated 44,000 to 98,000 deaths occur due to medical errors annually. Communication failure was found to be the root cause in 70% of…

26 CFR 1.367(a)-7T - Outbound transfers of property described in section 361(a) or (b).

Code of Federal Regulations, 2013 CFR

2013-04-01

... comply (temporary)—(i) Request for relief. A control group member's failure to timely comply with any requirement of this section shall be deemed not to have occurred if the control group member is able to... timely comply was due to reasonable cause and not willful neglect—(A) Time of submission. A control group...

26 CFR 1.367(a)-7T - Outbound transfers of property described in section 361(a) or (b).

Code of Federal Regulations, 2014 CFR

2014-04-01

... comply (temporary)—(i) Request for relief. A control group member's failure to timely comply with any requirement of this section shall be deemed not to have occurred if the control group member is able to... timely comply was due to reasonable cause and not willful neglect—(A) Time of submission. A control group...

Methodological issues in assessing changes in costs pre- and post-medication switch: a schizophrenia study example.

PubMed

Faries, Douglas E; Nyhuis, Allen W; Ascher-Svanum, Haya

2009-05-27

Schizophrenia is a severe, chronic, and costly illness that adversely impacts patients' lives and health care payer budgets. Cost comparisons of treatment regimens are, therefore, important to health care payers and researchers. Pre-Post analyses ("mirror-image"), where outcomes prior to a medication switch are compared to outcomes post-switch, are commonly used in such research. However, medication changes often occur during a costly crisis event. Patients may relapse, be hospitalized, have a medication change, and then spend a period of time with intense use of costly resources (post-medication switch). While many advantages and disadvantages of Pre-Post methodology have been discussed, issues regarding the attributability of costs incurred around the time of medication switching have not been fully investigated. Medical resource use data, including medications and acute-care services (hospitalizations, partial hospitalizations, emergency department) were collected for patients with schizophrenia who switched antipsychotics (n = 105) during a 1-year randomized, naturalistic, antipsychotic cost-effectiveness schizophrenia trial. Within-patient changes in total costs per day were computed during the pre- and post-medication change periods. In addition to the standard Pre-Post analysis comparing costs pre- and post-medication change, we investigated the sensitivity of results to varying assumptions regarding the attributability of acute care service costs occurring just after a medication switch that were likely due to initial medication failure. Fifty-six percent of all costs incurred during the first week on the newly initiated antipsychotic were likely due to treatment failure with the previous antipsychotic. Standard analyses suggested an average increase in cost-per-day for each patient of $2.40 after switching medications. However, sensitivity analyses removing costs incurred post-switch that were potentially due to the failure of the initial medication suggested decreases in costs in the range of $4.77 to $9.69 per day post-switch. Pre-Post cost analyses are sensitive to the approach used to handle acute-service costs occurring just after a medication change. Given the importance of quality economic research on the cost of switching treatments, thorough sensitivity analyses should be performed to identify the impact of crisis events around the time of medication change.

Fatigue evaluation of socket welded piping in nuclear power plant

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

Vecchio, R.S.

1996-12-01

Fatigue failures in piping systems occur, almost without exception, at the welded connections. In nuclear power plant systems, such failures occur predominantly at the socket welds of small diameter piping ad fillet attachment welds under high-cycle vibratory conditions. Nearly all socket weld fatigue failures are identified by leaks which, though not high in volume, generally are costly due to attendant radiological contamination. Such fatigue cracking was recently identified in the 3/4 in. diameter recirculation and relief piping socket welds from the reactor coolant system (RCS) charging pumps at a nuclear power plant. Consequently, a fatigue evaluation was performed to determinemore » the cause of cracking and provide an acceptable repair. Socket weld fatigue life was evaluated using S-N type fatigue life curves for welded structures developed by AASHTO and the assessment of an effective cyclic stress range adjacent to each socket weld. Based on the calculated effective tress ranges and assignment of the socket weld details to the appropriate AASHTO S-N curves, the socket weld fatigue lives were calculated and found to be in excellent agreement with the accumulated cyclic life to-date.« less

Chiasma failures and chromosome association in Rhoeo spathacea var. variegata.

PubMed

Lin, Y J

1982-01-01

In Rhoeo spathacea var. variegata (2n = 2x = 12), the most frequent meiotic configuration was the chain-of-12 chromosomes (36%) and the second most frequent was the ring-of-12 chromosomes (25.6%). All six possible two-chain situations and eleven of the twelve possible three-chain situations were observed. A maximum of five chains was observed in four cells. The size of chains ranged from on through twelve chromosomes. The mean number of chiasma failures was 1.36 +/- 0.07 per cell and 0.1133 per pair of chromosome arms. Because the observed frequencies of various configurations agree with the expected, which were calculated under the assumption that chiasma failure is equally likely at each of the twelve positions around the ring, it was concluded that chiasma failures occurred at random among the arm-positions. Due to the lengths of arm-pairs in the ring vary considerably, the randomness may mean that chiasma formation was restricted to small terminal regions on all chromosomes.

Common Cause Failures and Ultra Reliability

NASA Technical Reports Server (NTRS)

Jones, Harry W.

2012-01-01

A common cause failure occurs when several failures have the same origin. Common cause failures are either common event failures, where the cause is a single external event, or common mode failures, where two systems fail in the same way for the same reason. Common mode failures can occur at different times because of a design defect or a repeated external event. Common event failures reduce the reliability of on-line redundant systems but not of systems using off-line spare parts. Common mode failures reduce the dependability of systems using off-line spare parts and on-line redundancy.

Hardness and microstructure analysis of damaged gear caused by adhesive wear

NASA Astrophysics Data System (ADS)

Mahendra, Rizky Budi; Nugroho, Sri; Ismail, Rifky

2018-03-01

This study was a result from research on repairing project of damaged elevator gear box. The objective of this research is to analyze the failure part on elevator gearbox at flourmill factory. The equipment was damaged after one year installed and running on factory. Severe wear was occurred on high speed helical gear. These helical gear was one of main part of elevator gearbox in flour mill manufacture. Visually, plastic deformation didn't occurred and not visible on the failure helical gear shaft. Some test would be performed to check the chemical composition, microstructure and hardness of failure helical gear. The material of failure helical gear shaft was a medium carbon steel alloy. The microstructure was showed a martensitic phase formed on the surface to the center area of gear shaft. Otherwise, the depth of hardness layer slight formed on surface and lack depth of hardness layer was a main trigger of severe wear. It was not enough to resist wear due to friction caused by rolling and sliding on surface between high speed gear and low speed gear. Enhancement of hardness layer on surface and depth of hardness layer will make the component has more long life time. Furthermore, to perform next research is needed to analyze the reliability of enhanced hardness on layer and depth of hardness layer on helical gear shaft.

Forensic analysis of rockfall scars

NASA Astrophysics Data System (ADS)

de Vilder, Saskia J.; Rosser, Nick J.; Brain, Matthew J.

2017-10-01

We characterise and analyse the detachment (scar) surfaces of rockfalls to understand the mechanisms that underpin their failure. Rockfall scars are variously weathered and comprised of both discontinuity release surfaces and surfaces indicative of fracturing through zones of previously intact rock, known as rock bridges. The presence of rock bridges and pre-existing discontinuities is challenging to quantify due to the difficulty in determining discontinuity persistence below the surface of a rock slope. Rock bridges form an important control in holding blocks onto rockslopes, with their frequency, extent and location commonly modelled from the surface exposure of daylighting discontinuities. We explore an alternative approach to assessing their role, by characterising failure scars. We analyse a database of multiple rockfall scar surfaces detailing the areal extent, shape, and location of broken rock bridges and weathered surfaces. Terrestrial laser scanning and gigapixel imagery were combined to record the detailed texture and surface morphology. From this, scar surfaces were mapped via automated classification based on RGB pixel values. Our analysis of the resulting data from scars on the North Yorkshire coast (UK) indicates a wide variation in both weathering and rock bridge properties, controlled by lithology and associated rock mass structure. Importantly, the proportion of rock bridges in a rockfall failure surface does not increase with failure size. Rather larger failures display fracturing through multiple rock bridges, and in contrast smaller failures fracture occurs only through a single critical rock bridge. This holds implications for how failure mechanisms change with rockfall size and shape. Additionally, the location of rock bridges with respect to the geometry of an incipient rockfall is shown to determine failure mode. Weathering can occur both along discontinuity surfaces and previously broken rock bridges, indicating the sequential stages of progressively detaching rockfall. Our findings have wider implications for hazard assessment where rock slope stability is dependent on the nature of rock bridges, how this is accounted for in slope stability modelling, and the implications of rock bridges on long-term rock slope evolution.

Epidemiology of Pneumocystis carinii pneumonia in an era of effective prophylaxis: the relative contribution of non-adherence and drug failure.

PubMed

Lundberg, B E; Davidson, A J; Burman, W J

2000-11-10

To determine the relative contribution of patient non-adherence, provider failure to prescribe prophylaxis, and drug failure to the continued occurrence of Pneumocystis carinii pneumonia (PCP), and to determine correlates of non-adherence. Retrospective case-control study. Patients with confirmed or presumptive PCP from May 1995 to September 1997 who had at least 6 months of prior HIV care (cases) were compared to controls matched for initial CD4 cell count and date of initial HIV care. The incidence of PCP declined by 85% in the 28 months of the study. Of the 118 cases of PCP identified, 59 (50%) were in HIV care for > 6 months prior to PCP diagnosis. In a multivariate logistic regression model, risk factors for PCP among patients in HIV care were patient non-adherence [odds ratio (OR), 12.4; 95% confidence interval (CI), 6.4-23.5], use of prophylaxis other than trimethoprim-sulfamethoxazole (OR, 27.0; 95% CI, 13.8-52.9), and absence of antiretroviral use (OR, 7.5; 95% CI, 4.5-12.5). Provider non-adherence occurred in one out of 59 cases (2%), and five out of 106 controls (5%). Of the patients who developed PCP on prophylaxis, 18 cases (30%) appeared due to drug failure; there were no cases of apparent drug failure among patients on trimethoprim-sulfamethoxazole. In multivariate analysis, non-adherence was more common among patients of non-white race, those with a history of injecting drug use, and those with active substance abuse or psychiatric illness. Patient non-adherence was the most common reason for the occurrence of PCP among patients in HIV care; provider non-adherence was uncommon. Drug failure occurred only among patients on prophylaxis other than trimethoprim-sulfamethoxazole.

Spoil pile instabilities with reference to a strip coal mine in Turkey: mechanisms and assessment of deformations

NASA Astrophysics Data System (ADS)

Kasmer, Ozgu; Ulusay, Resat; Gokceoglu, Candan

2006-02-01

With the increasing adoption of the surface mining of coal, problems associated with spoil pile instability, which affects resource recovery, mining cost, and safety and presents environmental hazards, have become a matter of prime concern to mine planners and operators. The study of geotechnical aspects is thus very important in the rational planning for the disposal, reclamation, treatment and utilization of spoil material. A strip coal mine, one of the largest open pit mines in Turkey, is located in Central Anatolia and provides coal to a thermal power station. Coal production is carried out in two adjacent open pits, the Central Pit and South Pit. A large-scale spoil pile instability over an area of 0.3 km2 occurred within the dumping area of the Central pit. In addition, small-scale movement occurred in the outside dumping area. This paper outlines the results of field and laboratory investigations to describe the mechanisms of the spoil pile instabilities and to assess deformations monitored over a long period following the failure. Shear test results indicate that the interface between the floor and spoil material dumped by dragline has a negligible cohesion and is the most critical plane of weakness for spoil pile instability. Back analyses based on the method of limit equilibrium and the numerical modelling technique, and observations in the pit revealed that failure occurred along a combined sliding surface consisting of a circular surface through the spoil material itself and a planar surface passing along the interface between the spoil piles and floor. The analyses also indicated that pore water pressure ratios of about 0.25 satisfy limiting equilibrium condition and that rainfall about one month before the failure may be a contributing factor to the instability. Movement monitoring data obtained following the failure over a 1.5-year period suggested that the ongoing deformations were mainly due to compaction of the spoil material. Based on the monitoring data and the results of the analyses, the failure mode of the local instability occurring at the outside dumping area was considerably similar to that of the large instability.

Refeeding syndrome: a forgotten and potentially lethal entity.

PubMed

Aissaoui, Y; Hammi, S; Tagajdid, R; Chkoura, K; Boughalem, M

2016-05-01

Refeeding syndrome (RS) is defined as the fluid, electrolyte, metabolic, and clinical disturbances that occur after nutrition of patients who have been undernourished or fasting for a prolonged period. This syndrome has been recognized for several decades but is most often overlooked and underdiagnosed by health professionals. The authors report a RS in a patient subjected to prolonged fasting after being kidnapped by a criminal gang. Refeeding resulted in severe hypophosphatemia, neurological impairments, and hematologic disorders. The patient died due to septic shock with multiple organ failure secondary to aspiration pneumonia. In this case, the failure to recognize RS was decisive in the fatal outcome. Professionals must be aware of this disease to prevent and treat it properly.

Investigation and treatment for iron deficiency in heart failure: the unmet need in Lower and Middle Income Countries.

PubMed

Makubi, Abel; Roberts, David J

2017-06-01

Frank iron deficiency has been associated with a wide range of cardiac and pulmonary abnormalities including non-ischaemic cardiomyopathy. Iron deficiency anaemia and isolated iron deficiency are well-defined adverse prognostic factors in non-ischaemic cardiac failure. Furthermore, iron-deficient patients in chronic heart failure with a serum ferritin of <100 μg/l or <300 μg/l with reduced transferrin saturation of <20%, who were given intravenous iron showed improved clinical outcomes. Iron deficiency with or without anaemia affects over a quarter of the world's population, but the impact of iron deficiency in heart failure and the effective management of iron deficiency in heart failure in Lower and Middle Income Countries (LMICs) is not well described. Heart failure in African cohorts occurs at a younger age than in North America and Europe and is more likely to be due to hypertension. Recent studies suggest that iron deficiency anaemia, which is very common in heart failure patients in Africa, and iron deficiency are independently associated with a poor prognosis in heart failure. Preliminary data suggest that iron deficiency in patients with heart failure can be treated with oral iron, with significant beneficial effects on haematological and physiological variables. Cost may prohibit the use of intravenous iron on a large scale in LMICs and optimal regimes to treat iron deficiency in heart failure patients with oral iron therapy remain to be defined. © 2017 John Wiley & Sons Ltd.

The Impact of Thermocycling Process on the Dislodgement Force of Different Endodontic Cements

PubMed Central

Saghiri, Mohammad Ali; Asatourian, Armen; Garcia-Godoy, Franklin; Gutmann, James L.; Sheibani, Nader

2013-01-01

To evaluate the effects of thermocycling (500 cycles, 5°C/55°C) on the push-out bond strength of calcium silicate based cements including WMTA, Nano-WMTA, and Bioaggregate to root dentin. Forty-eight dentin slices were prepared and divided into 3 groups (n = 16) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate. After incubation, half of the samples were thermocycled while the other half remained untreated. Push-out bond strength was calculated, and the modes of the bond failures were determined by SEM. The highest bond strength was seen in nonthermocycled Nano-WMTA samples and the lowest in thermocycled Bioaggregate samples. The significant differences between nonthermocycled and thermocycled samples were only noticed in WMTA and Nano-WMTA groups (P < 0.001). The mode of failure for thermocycled samples of all three cements was mostly cohesive. Thermocycling process can drastically affect the push-out bond strength of calcium silicate based cements. The intrastructural damages occurred due to the thermal stresses, causing cohesive failures in set materials. Sealing property of endodontic cements which have experienced the thermal stresses can be jeopardized due to occlusal forces happening in furcation cites. PMID:24063004

Oblique impacts into low impedance layers

NASA Astrophysics Data System (ADS)

Stickle, A. M.; Schultz, P. H.

2009-12-01

Planetary impacts occur indiscriminately, in all locations and materials. Varied geologic settings can have significant effects on the impact process, including the coupling between the projectile and target, the final damage patterns and modes of deformation that occur. For example, marine impact craters are not identical to impacts directly into bedrock or into sedimentary materials, though many of the same fundamental processes occur. It is therefore important, especially when considering terrestrial impacts, to understand how a low impedance sedimentary layer over bedrock affects the deformation process during and after a hypervelocity impact. As a first step, detailed comparisons between impacts and hydrocode models were performed. Experiments performed at the NASA Ames Vertical Gun Range of oblique impacts into polymethylmethacrylate (PMMA) targets with low impedance layers were performed and compared to experiments of targets without low impedance layers, as well as to hydrocode models under identical conditions. Impact velocities ranged from 5 km/s to 5.6 km/s, with trajectories from 30 degrees to 90 degrees above the horizontal. High-speed imaging provided documentation of the sequence and location of failure due to impact, which was compared to theoretical models. Plasticine and ice were used to construct the low impedance layers. The combination of experiments and models reveals the modes of failure due to a hypervelocity impact. How such failure is manifested at large scales can present a challenge for hydrocodes. CTH models tend to overestimate the amount of damage occurring within the targets and have difficulties perfectly reproducing morphologies; nevertheless, they provide significant and useful information about the failure modes and style within the material. CTH models corresponding to the experiments allow interpretation of the underlying processes involved as well as provide a benchmark for the experimental analysis. The transparency of PMMA allows a clear view of failure patterns within the target, providing a 3D picture of the final damage, as well as damage formation and propagation. Secondly, PMMA has mechanical properties similar to those of brittle rocks in the upper crust, making it an appropriate material for comparison to geologic materials. An impact into a PMMA target with a one-projectile-diameter thick plasticine layer causes damage distinct from an impact into a PMMA target without a low impedance layer. The extent of the final damage is much less in the target with the low impedance layer and begins to form at later times, there is little to no crater visible on the surface, and the formation and propagation of the damage is completely different, creating distinct subsurface damage patterns. Three-dimensional CTH hydrocode models show that the pressure history of material around and underneath the impact point is also different when a low impedance layer is present, leading to the variations in damage forming within the targets.

Lubrication and failure mechanisms of molybdenum disulfide films. 1: Effect of atmosphere

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1978-01-01

Friction, wear, and wear lives of rubbed molybdenum disulfide (MoS2 films applied to sanded 440C HT steel surfaces were evaluated in moist air, dry air, and dry argon. Optical microscope observations were made as a function of sliding distance to determine the effect of moisture and oxygen on the lubricating and failure mechanisms of MoS2 films. In general, the lubrication process consisted of the formation of a thin, metallic colored, coalesced film of MoS2 that flowed between the surfaces in relative motion. In air, failure was due to the transformation of the metallic colored, coalesced films to a black, powdery material. Water in the air appeared to accelerate the transformation rate. In argon, no transformation of MoS2 was observed with the microscope, but cracking and spalling of the coalesced film occurred and resulted in the gradual depletion of the film.

Clavicle anatomical osteosynthesis plate breakage - failure analysis report based on patient morphological parameters.

PubMed

Marinescu, Rodica; Antoniac, Vasile Iulian; Stoia, Dan Ioan; Lăptoiu, Dan Constantin

2017-01-01

Clavicle fracture reported incidence is about 5% of fractures in adult; among them, those located in the middle third of the shaft represent more than 80% from the total of cases. Due to the special morphological and biomechanical constraints of the clavicle, several methods for restoring morphological integrity in these fractures are described, including conservative, non-surgical treatment. The last 10 years of clinical studies in the field have favored the surgical treatment for selected cases; several osteosynthesis implants are in use - mostly anatomical plates with specific advantages and documented complications. A failed anatomical clavicle plate was explanted and analyzed after a protocol using stereomicroscopy, scanning electron microscopy and energy dispersive spectrometry. Based on the computed tomography (CT) scan determination of patient morphological parameters, a finite elements analysis of the failure scenario was completed. The failure analysis has proved that the plate breakage had occurred in the point of maximal elastic stress and minor deformation. The clinical implication is that no hole should remain free of screw during clavicle plate fixation and the implant should be chosen based on patient morphological parameters. In comminuted clavicle fracture, anatomic bridging with locked plate technique may lead to implant failure due to increase of the stress in the midshaft area. Thorough knowledge of anatomy and morphology of complex bones like the clavicle is necessary. Modern osteosynthesis anatomical implants are still to be improved.

Mechanics of dual-mode dilative failure in subaqueous sediment deposits

NASA Astrophysics Data System (ADS)

You, Yao; Flemings, Peter; Mohrig, David

2014-07-01

We introduce dual-mode dilative failure with flume experiments. Dual-mode dilative failure combines slow and steady release of sediments by breaching with periodic sliding, which rapidly releases an internally coherent wedge of sediments. It occurs in dilative sandy deposits. This periodic slope failure results from cyclic evolution of the excess pore pressure in the deposit. Sliding generates large, transient, negative excess pore pressure that strengthens the deposit and allows breaching to occur. During breaching, negative excess pore pressure dissipates, the deposit weakens, and ultimately sliding occurs once again. We show that the sliding frequency is proportional to the coefficient of consolidation. We find that thicker deposits are more susceptible to dual-mode dilative failure. Discovery of dual-mode dilative failure provides a new mechanism to consider when interpreting the sedimentary deposits linked to submarine slope failures.

Complications and total care of a child with acute leukemia.

PubMed

Vietti, T J; Ragab, A H

1975-03-01

The complications which occur in a child with acute leukemia depend on the stage of the disease and the therapeutic regiman. Most children will present with some manifestation of marrow failure. An occasional child will have marked leukocytosis and disturbance of organ function due to massive leukemic infiltrates. Metabolic disturbances such as hyperuricemia and hyperphosphatemia-hypocalcemia may develop, expecially after therapy is initiated. The myelosuppression and immunosuppression due to drug toxicity may result in opportunistic infections. Other toxicities which can occur with a chemotherapeutic regimen are numerois and varied, and the physician must be cognizant of them in order to minimize damage. Therapy to the central nervous system, either for subclinical or clinical disease, has been associated with a variety of symptoms ranging from meningismus to paraplegia and death. To prevent the development of these complications, and to manage them effectively if they occur, the physician must be knowlegeable about their etiology, clinical and laboratory manifestations, and treatment.

Problematic protocols: An overview of medical research protocols not approved by the LUMC medical ethics review committee.

PubMed

Tersmette, Derek Gideon; Engberts, Dirk Peter

2017-01-01

The Committee for Medical Ethics (CME) of Leiden University Medical Center (LUMC) was established as the first medical ethics reviewing committee (MREC) in the Netherlands. In the period 2000-2010 the CME received 2,162 protocols for review. Some of these protocols were never approved. Until now, there has existed neither an overview of these failed protocols nor an overview of the reasons for their failure. This report draws on data from the digital database, the physical archives, and the minutes of the meetings of the CME. Additional information has been obtained from the Central Committee on Research involving Human Subjects (CCRH) and survey-based research. Protocols were itemized based on characteristic features and their reviewing procedures were analyzed. In total, 1,952 out of 2,162 research protocols submitted during 2000-2010 (90.3%) were approved by the CME; 210 of 2,162 protocols (9.7%) were not approved. Of these 210 protocols, 177 failed due to reasons not related to CME reviewing. In 15 cases CME reviewing led to protocol failure, while another 10 protocols were rejected outright. Eight of the 210 submitted protocols without approval had been conducted prior to submission. In the aforementioned period, little protocol failure occurred. For the most part, protocol failure was caused by problems that are not CME related. This type of failure has several identifiable factors, none of which have anything to do with the ethical reviewing procedure by the CME. A mere 1.2% of protocols failed due to ethical review. Unacceptable burden and risks to the subject and an inadequate methodology are the most common reasons for this CME-related protocol failure.

Comminuted olecranon fracture fixation with pre-contoured plate: Comparison of composite and cadaver bones

PubMed Central

Hamilton Jr, David A; Reilly, Danielle; Wipf, Felix; Kamineni, Srinath

2015-01-01

AIM: To determine whether use of a precontoured olecranon plate provides adequate fixation to withstand supraphysiologic force in a comminuted olecranon fracture model. METHODS: Five samples of fourth generation composite bones and five samples of fresh frozen human cadaveric left ulnae were utilized for this study. The cadaveric specimens underwent dual-energy X-ray absorptiometry (DEXA) scanning to quantify the bone quality. The composite and cadaveric bones were prepared by creating a comminuted olecranon fracture and fixed with a pre-contoured olecranon plate with locking screws. Construct stiffness and failure load were measured by subjecting specimens to cantilever bending moments until failure. Fracture site motion was measured with differential variable resistance transducer spanning the fracture. Statistical analysis was performed with two-tailed Mann-Whitney-U test with Monte Carlo Exact test. RESULTS: There was a significant difference in fixation stiffness and strength between the composite bones and human cadaver bones. Failure modes differed in cadaveric and composite specimens. The load to failure for the composite bones (n = 5) and human cadaver bones (n = 5) specimens were 10.67 nm (range 9.40-11.91 nm) and 13.05 nm (range 12.59-15.38 nm) respectively. This difference was statistically significant (P ˂ 0.007, 97% power). Median stiffness for composite bones and human cadaver bones specimens were 5.69 nm/mm (range 4.69-6.80 nm/mm) and 7.55 nm/mm (range 6.31-7.72 nm/mm). There was a significant difference for stiffness (P ˂ 0.033, 79% power) between composite bones and cadaveric bones. No correlation was found between the DEXA results and stiffness. All cadaveric specimens withstood the physiologic load anticipated postoperatively. Catastrophic failure occurred in all composite specimens. All failures resulted from composite bone failure at the distal screw site and not hardware failure. There were no catastrophic fracture failures in the cadaveric specimens. Failure of 4/5 cadaveric specimens was defined when a fracture gap of 2 mm was observed, but 1/5 cadaveric specimens failed due to a failure of the triceps mechanism. All failures occurred at forces greater than that expected in postoperative period prior to healing. CONCLUSION: The pre-contoured olecranon plate provides adequate fixation to withstand physiologic force in a composite bone and cadaveric comminuted olecranon fracture model. PMID:26495247

Submarine slope failures along the convergent continental margin of the Middle America Trench

NASA Astrophysics Data System (ADS)

Harders, Rieka; Ranero, CéSar R.; Weinrebe, Wilhelm; Behrmann, Jan H.

2011-06-01

We present the first comprehensive study of mass wasting processes in the continental slope of a convergent margin of a subduction zone where tectonic processes are dominated by subduction erosion. We have used multibeam bathymetry along ˜1300 km of the Middle America Trench of the Central America Subduction Zone and deep-towed side-scan sonar data. We found abundant evidence of large-scale slope failures that were mostly previously unmapped. The features are classified into a variety of slope failure types, creating an inventory of 147 slope failure structures. Their type distribution and abundance define a segmentation of the continental slope in six sectors. The segmentation in slope stability processes does not appear to be related to slope preconditioning due to changes in physical properties of sediment, presence/absence of gas hydrates, or apparent changes in the hydrogeological system. The segmentation appears to be better explained by changes in slope preconditioning due to variations in tectonic processes. The region is an optimal setting to study how tectonic processes related to variations in intensity of subduction erosion and changes in relief of the underthrusting plate affect mass wasting processes of the continental slope. The largest slope failures occur offshore Costa Rica. There, subducting ridges and seamounts produce failures with up to hundreds of meters high headwalls, with detachment planes that penetrate deep into the continental margin, in some cases reaching the plate boundary. Offshore northern Costa Rica a smooth oceanic seafloor underthrusts the least disturbed continental slope. Offshore Nicaragua, the ocean plate is ornamented with smaller seamounts and horst and graben topography of variable intensity. Here mass wasting structures are numerous and comparatively smaller, but when combined, they affect a large part of the margin segment. Farther north, offshore El Salvador and Guatemala the downgoing plate has no large seamounts but well-defined horst and graben topography. Off El Salvador slope failure is least developed and mainly occurs in the uppermost continental slope at canyon walls. Off Guatemala mass wasting is abundant and possibly related to normal faulting across the slope. Collapse in the wake of subducting ocean plate topography is a likely failure trigger of slumps. Rapid oversteepening above subducting relief may trigger translational slides in the middle Nicaraguan upper Costa Rican slope. Earthquake shaking may be a trigger, but we interpret that slope failure rate is lower than recurrence time of large earthquakes in the region. Generally, our analysis indicates that the importance of mass wasting processes in the evolution of margins dominated by subduction erosion and its role in sediment dynamics may have been previously underestimated.

Time-related patterns of ventricular shunt failure.

PubMed

Kast, J; Duong, D; Nowzari, F; Chadduck, W M; Schiff, S J

1994-11-01

Proximal obstruction is reported to be the most common cause of ventriculoperitoneal (VP) shunt failure, suggesting that imperfect ventricular catheter placement and inadequate valve mechanisms are major causes. This study retrospectively examined patterns of shunt failure in 128 consecutive patients with symptoms of shunt malfunction over a 2-year period. Factors analyzed included site of failure, time from shunt placement or last revision to failure, age of patient at time of failure, infections, and primary etiology of the hydrocephalus. One hundred of these patients required revisions; 14 revisions were due to infections. In this series there was a higher incidence of distal (43%) than of proximal (35%) failure. The difference was not statistically significant when the overall series was considered; however, when factoring time to failure as a variable, marked differences were noted regardless of the underlying cause of hydrocephalus or the age of the patient. Of the 49 patients needing a shunt revision or replacement within 2 years of the previous operation, 50% had proximal malfunction, 14% distal, and 10% had malfunctions attributable directly to the valve itself. Also, 12 of the 14 infections occurred during this time interval. In sharp contrast, of the 51 patients having shunt failure from 2 to more than 12 years after the previous procedure, 72% had distal malfunction, 21% proximal, and only 6% had a faulty valve or infection. This difference between time to failure for proximal versus distal failures was statistically significant (P < 0.00001 for both Student's t-test and non-parametric Mann-Whitney U-test).(ABSTRACT TRUNCATED AT 250 WORDS)

Early failure mechanisms of constrained tripolar acetabular sockets used in revision total hip arthroplasty.

PubMed

Cooke, Christopher C; Hozack, William; Lavernia, Carlos; Sharkey, Peter; Shastri, Shani; Rothman, Richard H

2003-10-01

Fifty-eight patients received an Osteonics constrained acetabular implant for recurrent instability (46), girdlestone reimplant (8), correction of leg lengthening (3), and periprosthetic fracture (1). The constrained liner was inserted into a cementless shell (49), cemented into a pre-existing cementless shell (6), cemented into a cage (2), and cemented directly into the acetabular bone (1). Eight patients (13.8%) required reoperation for failure of the constrained implant. Type I failure (bone-prosthesis interface) occurred in 3 cases. Two cementless shells became loose, and in 1 patient, the constrained liner was cemented into an acetabular cage, which then failed by pivoting laterally about the superior fixation screws. Type II failure (liner locking mechanism) occurred in 2 cases. Type III failure (femoral head locking mechanism) occurred in 3 patients. Seven of the 8 failures occurred in patients with recurrent instability. Constrained liners are an effective method for treatment during revision total hip arthroplasty but should be used in select cases only.

Comparison of the discontinuation rates and side-effect profiles of pilocarpine and cevimeline for xerostomia in primary Sjögren's syndrome.

PubMed

Noaiseh, Ghaith; Baker, Joshua F; Vivino, Frederick B

2014-01-01

There are currently no head-to-head comparisons of sialagogues for Primary Sjögren's syndrome (pSS). We compared the tolerability and side effect profile of pilocarpine and cevimeline in patients with pSS and determined clinical, laboratory and pathological variables associated with therapeutic failure. We retrospectively reviewed the use of pilocarpine and cevimeline in 118 patients with pSS who fulfilled the 2002 American European Consensus Group criteria in a University-based setting. Clinical, laboratory and pathological baseline variables were collected. Failure of therapy was defined as the clinician or patient's decision to stop treatment either due to lack of efficacy or side effects. Cevimeline was associated with lower failure rates compared to pilocarpine among first-time users: 27% vs. 47% (p=0.02), and all users: 32% vs. 61% (p<0.001). Severe sweating was the most frequent side effect leading to cessation of therapy and occurred more frequently in pilocarpine (25%) than cevimeline (11%) users (p=0.02). Patients who previously failed one secretagogue were less likely to discontinue treatment with the other agent, 52% of first-time users vs. 27% of second-time users (p=0.004). Only ANA positivity was associated with failure: [59% vs. 38%] (p=0.03). pSS patients were more likely to continue cevimeline than pilocarpine long-term due to fewer reported side effects with cevimeline. Therapeutic failure of one secretagogue did not predict similar results with the other since second time users were more likely to continue long-term treatment.

Seizure outcome after AED failure in pediatric focal epilepsy: impact of underlying etiology.

PubMed

Wirrell, Elaine C; Wong-Kisiel, Lily C; Nickels, Katherine C

2014-05-01

This study aimed to identify long-term seizure outcome in pediatric nonsyndromic focal epilepsy after failure of serial antiepileptic drugs (AEDs) due to lack of efficacy. Children (1 month-17 years) with new-onset focal epilepsy not meeting the criteria for a defined electroclinical syndrome diagnosed between 1980 and 2009 while residing in Olmsted County, MN, were retrospectively identified. Medical records of those followed for ≥2 years were reviewed to assess etiology, the number of AEDs that failed due to lack of efficacy, and seizure outcome at final follow-up. Etiology was classified into structural/metabolic, genetic, or unknown. Favorable outcome was defined as seizure freedom ≥1 year, on or off AEDs, without prior epilepsy surgery. Poor outcome was defined as ongoing seizures in the preceding year or having undergone prior epilepsy surgery. Nonsyndromic focal epilepsy accounted for 275/468 (59%) of all patients with newly diagnosed epilepsy--of these, 256 (93%) were followed for a minimum of two years and were included in the study. Median duration of follow-up was 10.0 years. At least one AED had failed due to lack of efficacy in 100 (39.1%) children. Favorable outcomes occurred in 149/156 (95.5%) children with no AED failure, 16/30 (53.3%) with one AED failure, 8/25 (32%) with two AED failures, and only 2/45 (4.4%) with three AED failures. After two AED failures, the seizures of nearly one-quarter of children who had epilepsy with an unknown cause responded favorably to the third AED compared with only 7.8% of the cohort that had epilepsy with a structural/metabolic cause. Children with a remote brain insult had a significantly higher likelihood of favorable outcome with serial AEDs than those with other structural abnormalities. Etiology is an important determinant of pharmacoresistance in nonsyndromic focal epilepsy. Surgical evaluation should be considered after failure of 1-2 AEDs in those who have epilepsy with structural causes, excluding remote brain insults. Conversely, as surgical success is lower with normal MRI or more diffuse brain insults, it appears reasonable to hold off surgical evaluation until 2-3 AEDs have failed in such children. Copyright © 2014 Elsevier Inc. All rights reserved.

NALP3-mediated inflammation is a principal cause of progressive renal failure in oxalate nephropathy

PubMed Central

Knauf, Felix; Asplin, John R.; Granja, Ignacio; Schmidt, Insa M.; Moeckel, Gilbert; David, Rachel; Flavell, Richard A.; Aronson, Peter S.

2013-01-01

Oxalate nephropathy with renal failure is caused by multiple disorders causing hyperoxaluria due to either overproduction of oxalate (primary hyperoxaluria) or excessive absorption of dietary oxalate (enteric hyperoxaluria). To study the etiology of renal failure in crystal-induced kidney disease, we created a model of progressive oxalate nephropathy by feeding mice a diet high in soluble oxalate (high oxalate in the absence of dietary calcium). Renal histology was characterized by intratubular calcium-oxalate crystal deposition with an inflammatory response in the surrounding interstitium. Oxalate nephropathy was not found in mice fed a high oxalate diet that also contained calcium. NALP3, also known as cryopyrin, has been implicated in crystal-associated diseases such as gout and silicosis. Mice fed the diet high in soluble oxalate demonstrated increased NALP3 expression in the kidney. Nalp3-null mice were completely protected from the progressive renal failure and death that occurred in wild-type mice fed the diet high in soluble oxalate. NALP3-deficiency did not affect oxalate homeostasis, thereby excluding differences in intestinal oxalate handling to explain the observed phenotype. Thus, progressive renal failure in oxalate nephropathy results primarily from NALP3-mediated inflammation. PMID:23739234

Elimination of Potential Electrical Stress During EMC (CS01) Testing

NASA Technical Reports Server (NTRS)

Erickson, Kenneth P.; Whittlesey, Albert C.; Vorperian, Vatche

2006-01-01

This viewgraph presentation reviews possible ways to eliminate electrical stress during Electromagneticic Compatibility (EMC) testing. The presentation reviews tests that have had problems due to electrical stress. On December 5, 1995 Cassini Radar instrument failed a functional test in preparation for EMC conducted susceptibility (CSO 1 ) testing. The instrument power supply did not turn on as required, and failure occurred prior to injection of CS test stimulus. A investigation of the failure was conducted. A PSPICE simulation of Cassini Radar 30V line using the EMC test setup was performed; the result of the simulation was an oscillation on the 30V input of the power supply. In another case: on December 28, 1999 an oscillation occurred on the input power line of the SlRTF Infrared Array Camera (IRAC) while preparing to perform CSOI testing, Resulted in damage to flight hardware. Subsequent to failure, JPL provided GSFC history and corrective action from Cassini Radar CSOI test failure GSFC implemented the same corrective action as JPL, except that the value of the resistor connected across the isolation transformer primary winding is 2.5 ohms instead of 50 ohms. Three recommendations are made: (1) Make EMC test community aware of the problem and potential solutions by presenting papers at major environmental test conferences (2) Include warnings and safeguards in EMC test requirements and procedures (3) Try to convince EMC test equipment suppliers to design a CSOl test fixture similar to fixture shown in the diagram

Comparison of retrievable stents and permanent stents for Budd-Chiari syndrome due to obstructive inferior vena cava.

PubMed

Bi, Yonghua; Chen, Hongmei; Ding, Penxu; Ren, Jianzhuang; Han, Xinwei

2018-05-30

To compare long-term outcomes of retrievable stents and permanent stents for BCS due to long-segment obstructive IVC. Between July 2000 and August 2016, 42 patients with BCS due to long-segment obstructive IVC were treated with retrievable stents (RS) and 41 patients were treated with permanent stents (PS). The retrievable stents was removed eventually after thrombus disappeared. Patients were subsequently followed-up by color Doppler sonography or CT scanning. All retrievable stent placements were successfully, and 37 retrievable stents were retrieved 8 to 29 days later. Forty-two stents were implanted in PS Group. One failure retrieval of retrievable stents occurred, and two failures of cannulations were found in PS Group. Two deaths may procedure-related and died from acute pulmonary thromboembolism perioperatively. One patient developed acute cerebral infarction and recovered after treatment. In PS Group, minor complications were found in 3 patients. The length of IVC lesion segment, length and thickness of IVC thrombus decreased significantly, and diameter of retrocaval IVC and diaphragm IVC increased significantly in both groups. During follow up, 3 patients died from liver failure in RS Group and 2 patients died in PS Group. RS Group showed a significantly higher primary patency rate than PS Group. Cumulative 1-, 3-, and 5-year secondary patency rates were 95.2%, 89.6%, 89.6% in RS Group, and 100%, 96.6%, 96.6% in PS Group (p= 0.7109). Retrievable stents is effective for BCS due to long-segment obstructive IVC, with a higher primary patency rate. This article is protected by copyright. All rights reserved.

Levofloxacin-induced hepatotoxicity and death.

PubMed

Gulen, Muge; Ay, Mehmet Oguzhan; Avci, Akkan; Acikalin, Ayca; Icme, Ferhat

2015-01-01

Drug-induced hepatotoxicity is a major cause of hepatocellular injury in patients admitting to emergency services with acute liver failure. Hepatic necrosis may be at varying degrees from mild elevations in transaminases to fulminant hepatitis, and even death. The case of a 53-year-old female patient with toxic hepatitis due to levofloxacin and multiple organ failure secondary to toxic hepatitis is presented. Patient suffered itching, redness, and rash after receiving a single dose of 750 mg of levofloxacin tablets for pulmonary infection 10 days ago. Skin lesions had regressed within 3 days, but desquamation formed all over the body. After the fifth day of drug intake, complaints of abdominal pain, vomiting, and yellowing in skin color had started. The patient was referred to our emergency department with these complaints 10 days after drug intake. Patient was thought as a candidate for liver transplant, but cardiopulmonary arrest occurred, and the patient died before she could be referred to a transplant center. This case is important because hepatotoxicity and death due to levofloxacin is uncommon in the literature.

Integrated Design Software Predicts the Creep Life of Monolithic Ceramic Components

NASA Technical Reports Server (NTRS)

1996-01-01

Significant improvements in propulsion and power generation for the next century will require revolutionary advances in high-temperature materials and structural design. Advanced ceramics are candidate materials for these elevated-temperature applications. As design protocols emerge for these material systems, designers must be aware of several innate features, including the degrading ability of ceramics to carry sustained load. Usually, time-dependent failure in ceramics occurs because of two different, delayedfailure mechanisms: slow crack growth and creep rupture. Slow crack growth initiates at a preexisting flaw and continues until a critical crack length is reached, causing catastrophic failure. Creep rupture, on the other hand, occurs because of bulk damage in the material: void nucleation and coalescence that eventually leads to macrocracks which then propagate to failure. Successful application of advanced ceramics depends on proper characterization of material behavior and the use of an appropriate design methodology. The life of a ceramic component can be predicted with the NASA Lewis Research Center's Ceramics Analysis and Reliability Evaluation of Structures (CARES) integrated design programs. CARES/CREEP determines the expected life of a component under creep conditions, and CARES/LIFE predicts the component life due to fast fracture and subcritical crack growth. The previously developed CARES/LIFE program has been used in numerous industrial and Government applications.

On 'large-scale' stable fiber displacement during interfacial failure in metal matrix composites

NASA Technical Reports Server (NTRS)

Petrich, R. R.; Koss, D. A.; Hellmann, J. R.; Kallas, M. N.

1993-01-01

Experimental results are presented to show that interfacial failure in sapphire-reinforced niobium is characterized by 'large-scale' (5-15 microns) plasticity-controlled fiber displacements occurring under increasing loads. The results are based on the responses during thin-slice fiber pushout tests wherein the fiber is supported over a hole twice the fiber diameter. The results describe an interfacial failure process that should also occur near fiber ends during pullout when a fiber is well-bonded to a soft, ductile matrix, such that eventual failure occurs by shear within the matrix near the interface.

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.

Failure Analysis of Fractured Poppet from Space Shuttle Orbiter Flow Control Valve

NASA Technical Reports Server (NTRS)

Russell, Richard

2010-01-01

This slide presentation reviews the failure analysis of a fractured poppet from a flow control valve (FCV) used on the space shuttle. This presentation has focused on the laboratory analysis of the failed hardware. The use of Scanning electron fractography during the investigation led to the conclusion that the poppet failed due to fatigue cracking that, most likely, occurred under changing loading conditions. The initial investigation led to a more thorough test of poppets that had been retired, this testing led to the conclusion that the thumbnail cracks in the flight hardware had existed for the life of the shuttle program. This led to a program to develop an eddy current technique that was capable of detecting small very tight cracks.

Development of design criteria for prevention of slope failures : design guide.

DOT National Transportation Integrated Search

1990-03-01

A total of 242 embankments were examined along a 122-mile transect of I-10 and I-20 highways in Louisiana. A total of 99 slope failures had occurred 8-15 years after construction (mean volume = 15,105 cu ft). Most of the failures occurred on slopes g...

A prospective randomized open-label crossover trial of regional citrate anticoagulation vs. anticoagulation free liver dialysis by the Molecular Adsorbents Recirculating System

PubMed Central

2012-01-01

Introduction The Molecular Adsorbent Recycling System (MARS) is used to treat patients with liver failure. Observational data suggest that citrate anticoagulation during MARS is feasible. Comparative studies on the optimal anticoagulation regimen during MARS are lacking. The aim of the current study was to evaluate two heparin-free anticoagulation regimens. Methods We performed a prospective randomized open-label crossover study of regional citrate anticoagulation against no anticoagulation. Ten patients (age 55 ± 11 years) with liver failure undergoing MARS treatment were included. The primary endpoint was completion of MARS sessions. Secondary endpoints included treatment efficacy and safety. Longevity of MARS treatment was plotted as a Kaplan-Meier estimate. Fisher's exact test was used for contingency table analysis. Results Of a total of 27 6-hour sessions, four sessions had to be terminated prematurely, three due to occlusive clotting of the extracorporeal circuit and one due to uncontrollable bleeding from the vascular access site. All four events occurred in the group without anticoagulation. Between group comparison demonstrated citrate anticoagulation to significantly increase the likelihood of completed MARS treatment (Fisher's exact test, P 0.04). This translates into higher bilirubin reduction ratios when citrate was applied (reduction ratio 0.25 vs. 0.15, P 0.02). Systemic ionized calcium concentrations were significantly reduced during citrate anticoagulation (P < 0.001) but remained within a safe range. We observed no major adverse events. Conclusions Regional citrate anticoagulation in patients with liver failure is feasible. Citrate anticoagulation provides superior patency of the extracorporeal circuit. Avoidance of anticoagulation during MARS results in significant loss of treatment efficacy, due to treatment downtime. Additional studies are required to identify the optimal anticoagulation regimen for extracorporeal circulation in patients with liver failure. PMID:22305273

Effects of pressure angle and tip relief on the life of speed increasing gearbox: a case study.

PubMed

Shanmugasundaram, Sankar; Kumaresan, Manivarma; Muthusamy, Nataraj

2014-01-01

This paper examines failure of helical gear in speed increasing gearbox used in the wind turbine generator (WTG). In addition, an attempt has been made to get suitable gear micro-geometry such as pressure angle and tip relief to minimize the gear failure in the wind turbines. As the gear trains in the wind turbine gearbox is prearranged with higher speed ratio and the gearboxes experience shock load due to atmospheric turbulence, gust wind speed, non-synchronization of pitching, frequent grid drops and failure of braking, the gear failure occurs either in the intermediate or high speed stage pinion. KISS soft gear calculation software was used to determine the gear specifications and analysis is carried out in ANSYS software version.11.0 for the existing and the proposed gear to evaluate the performance of bending stress tooth deflection and stiffness. The main objective of this research study is to propose suitable gear micro-geometry that is tip relief and pressure angle blend for increasing tooth strength of the helical gear used in the wind turbine for trouble free operation.

Clinical Management of Implant Prostheses in Patients with Bruxism

PubMed Central

Komiyama, Osamu; Lobbezoo, Frank; De Laat, Antoon; Iida, Takashi; Kitagawa, Tsuyoshi; Murakami, Hiroshi; Kato, Takao; Kawara, Misao

2012-01-01

There is general agreement that excessive stress to the bone-implant interface may result in implant overload and failure. Early failure of the implant due to excessive loading occurs shortly after uncovering the implant. Excess load on a final restoration after successful implant integration can result in physical failure of the implant structure. Many clinicians believe that overload of dental implants is a risk factor for vertical peri-implant bone loss and/or may be detrimental for the suprastructure in implant prostheses. It has been documented that occlusal parafunction, such as, bruxism (tooth grinding and clenching) affects the outcome of implant prostheses, but there is no evidence for a causal relation between the failures and overload of dental implants. In spite of this lack of evidence, often metal restorations are preferred instead of porcelain for patients in whom bruxism is presumed on the basis of tooth wear. The purpose of this paper is to discuss the importance of the occlusal scheme used in implant restorations for implant longevity and to suggest a clinical approach and occlusal materials for implant prostheses in order to prevent complications related to bruxism. PMID:22701484

Interventional Management of “Balloon-Uncrossable” Coronary Chronic Total Occlusion: Is There Any Way Out?

PubMed Central

2018-01-01

It has been estimated that coronary chronic total occlusion (CTO) is encountered in 15 to 20% patients referred for coronary angiography (CAG). The success of percutaneous coronary intervention (PCI) of CTO can be attributed to the vast array of hardware that has now become available and also to the vastly enhanced operator expertise. It is however realistic to state that despite the tremendous increase in the rate of success, there then comes a subset of CTO where PCI attempts fail. The reason for such failures given that other variables remain constant is the inability to cross the CTO lesion. This can be due to a failure to cross the lesion with a guide wire (despite guide wire escalation). The second cause of failure is the inability to cross the lesion with a balloon (balloon-uncrossable [BU] CTO). This can occur despite the successful placement of a guidewire in the distal true lumen. The BU lesions contribute 2% to 10% of CTO PCI failure cases. The author attempts to present a creative solution to assist crossing such lesions. PMID:29625510

Early warning indicators for process failure due to organic overloading by rapeseed oil in one-stage continuously stirred tank reactor, sewage sludge and waste digesters.

PubMed

Kleyböcker, A; Liebrich, M; Verstraete, W; Kraume, M; Würdemann, H

2012-11-01

Early warning indicators for process failures were investigated to develop a reliable method to increase the production efficiency of biogas plants. Organic overloads by the excessive addition of rapeseed oil were used to provoke the decrease in the gas production rate. Besides typical monitoring parameters, as pH, methane and hydrogen contents, biogas production rate and concentrations of fatty acids; carbon dioxide content, concentrations of calcium and phosphate were monitored. The concentration ratio of volatile fatty acids to calcium acted as an early warning indicator (EWI-VFA/Ca). The EWI-VFA/Ca always clearly and reliably indicated a process imbalance by exhibiting a 2- to 3-fold increase 3-7days before the process failure occurred. At this time, it was still possible to take countermeasures successfully. Furthermore, increases in phosphate concentration and in the concentration ratio of phosphate to calcium also indicated a process failure, in some cases, even earlier than the EWI-VFA/Ca. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

The initial flight anomalies of Skylab 1

NASA Astrophysics Data System (ADS)

At approximately 63 seconds into the flight of Skylab 1 on May 14, 1973, an anomaly occurred which resulted in the complete loss of the meteoroid shield around the orbital workshop. This was followed by the loss of one of the two solar array systems on the workshop and a failure of the inter stage adapter to separate from the S-II stage of the Saturn V launch vehicle. The investigation reported herein identified the most probable cause of this flight anomaly to be the breakup and loss of the meteoroid shield due to aerodynamic loads that were not accounted for in its design. The breakup of the meteoroid shield, in turn, broke the tie downs that secured one of the solar array systems to the workshop. Complete loss of this solar array system occurred at 593 seconds when the exhaust plume of the S-II stage retro-rockets impacted the partially deployed solar array system. Falling debris from the meteoroid shield also damaged the S-II inter stage adapter ordnance system in such a manner as to preclude separation. Of several possible failure modes of the meteoroid shield that were identified, the most probable in this particular flight was internal pressurization of its auxiliary tunnel which acted to force the forward end of the meteoroid shield away from the shell of the workshop and into the supersonic air stream. The pressurization of the auxiliary tunnel was due to the existence of several openings in the aft region of the tunnel. Another possible failure mode was the separation of the leading edge of the meteoroid shield from the shell of the workshop (particularly in the region of the folded ordnance panel) of sufficient extent to admit ram air pressures under the shield.

Sensitivity of the spiny dogfish (Squalus acanthias) to waterborne silver exposure.

PubMed

De Boeck, G; Grosell, M; Wood, C

2001-10-01

The physiological effects of waterborne silver exposure (added as AgNO(3)) on spiny dogfish, Squalus acanthias, were evaluated at 30, 200 and 685 microg silver per l in 30 per thousand seawater. These concentrations cover the toxic range observed for freshwater teleosts, where silver is extremely toxic, to seawater teleosts which tolerate higher silver concentrations. However, these levels are considerably higher than those that occur in the normal environment. At 685 microg l(-1), dogfish died within 24 h. Causes of death were respiratory as well as osmoregulatory failure. Arterial P(a)O(2) rapidly declined below 20 Torr, and blood acidosis (both respiratory and metabolic) occurred. Urea excretion increased dramatically and plasma urea dropped from 340 to 225 mM. There were pronounced increases in plasma Na(+), Cl(-), and Mg(2+), indicative of ionoregulatory failure due to increased diffusive permeability as well as inhibited NaCl excretion. At 200 microg l(-1), fish died between 24 and 72 h of silver exposure. The same physiological events occurred with a small time delay. At 30 microg l(-1), effects were much less severe, although slight mortality (12.5%) still occurred. Respiratory alkalosis occurred, together with moderate elevations in plasma Na(+) and Cl(-) levels. Silver accumulated to the highest concentrations on gills, with only low levels in the intestine, in accord with the virtual absence of drinking. Na(+)/K(+)-ATP-ase activities of gill and rectal gland tissue were impaired at the highest silver concentration. Normal gill function was impaired due to swelling and fusion of lamellae, lamellar aneurism and lifting of the lamellar epithelium. Our results clearly indicate that this elasmobranch is much more sensitive (about 10-fold) to silver than marine teleosts, with silver's toxic action exerted on the gill rather than on the intestine, in contrast to the latter.

Improving Self-Pierce Rivet Performance through Processing and Alloy Development

NASA Astrophysics Data System (ADS)

Van Hall, Stephen N.

Spot welding has been used to join steel sheet material in the past during automotive manufacturing. The increasing use of aluminum and mixed materials to achieve continually increasing fuel economy standards requires mechanical joining methods to provide adequate impact performance. One such mechanical joining process is self-pierce riveting (SPR). Self-pierce riveting has grown in popularity in recent years due to fast cycle times, high static strength and fatigue performance as well as the ability to join many different sheet material combinations. Self-pierce rivet utilization has become limited due to the material properties of the rivet in two main areas: the joining of high-strength sheet material and joining of multiple sheet material combinations using a single rivet geometry, referred to as commonization. Two specific case studies have been developed to assess the failures that occur and evaluate potential solutions: joining of press-hardened steel (PHS) to Al6111 and improved commonization ability using a two layer aluminum joint that is currently joined with a specialized rivet. Riveting trials have been performed on each of the two case studies using cold forged rivets produced from 10B37 steel that has been heat-treated through a quench and temper process to a range of hardness levels to evaluate the failures that occur within the rivet. The failures occur with two different modes: buckling of the rivet at hardness values below 550 HV when joining PHS and Al6111 and fractures that occur in the rivet tail at hardness values above 550 HV during joining in each of the case studies under evaluation. The fractures have been attributed to a high degree of hoop strain that forms when the rivets are flared beyond the design specifications. A method to replicate the rivet flaring procedure under laboratory conditions has been developed by flaring the rivets through various strain paths to induce a hoop strain and the resultant fractures. The flaring method shows the ability to replicate the types of fractures that were observed during joining attempts while monitoring applied force, crosshead displacement and strain at the point of fracture at the rivet tail using digital image correlation. Alternative alloys including 4130, 4340 and 5160 were evaluated alongside 10B37 for improved performance after quenching and tempering, austempering and after being intentionally decarburized to varying degrees. The heat-treatments were evaluated through microscopy, fractography, rivet flaring and joining attempts for each case study and alloy under investigation. All of the alternative alloys showed no significant performance gains after being quenched and tempered or austempered. However, hoop strain to failure during flaring was increased between 2-4x after the rivets had been intentionally decarburized. The intentionally decarburized rivets were evaluated through joining trials and provided successful joining for each of the case studies under investigation using 10B37 rivets. Rivets produced from 4340 and 5160 also showed instances of success during joining attempts. The Cockroft and Latham failure criterion was evaluated in regards to rivet flaring through the development of finite element simulations using Abaqus. The Cockroft and Latham failure criterion was able to successfully predict the location of riveting fractures through multiple strain paths, rivet geometries and microstructures. Cockroft and Latham values from tensile tests of 10B37 wire led to an underestimate of the strain to failure when compared to the rivet flaring process for quenched and tempered rivets but was very similar to the strain predicted for rivets that had been intentionally decarburized.

Failed awake craniotomy: a retrospective analysis in 424 patients undergoing craniotomy for brain tumor.

PubMed

Nossek, Erez; Matot, Idit; Shahar, Tal; Barzilai, Ori; Rapoport, Yoni; Gonen, Tal; Sela, Gal; Korn, Akiva; Hayat, Daniel; Ram, Zvi

2013-02-01

Awake craniotomy for removal of intraaxial tumors within or adjacent to eloquent brain regions is a well-established procedure. However, awake craniotomy failures have not been well characterized. In the present study, the authors aimed to analyze and assess the incidence and causes for failed awake craniotomy. The database of awake craniotomies performed at Tel Aviv Medical Center between 2003 and 2010 was reviewed. Awake craniotomy was considered a failure if conversion to general anesthesia was required, or if adequate mapping or monitoring could not have been achieved. Of 488 patients undergoing awake craniotomy, 424 were identified as having complete medical, operative, and anesthesiology records. The awake craniotomies performed in 27 (6.4%) of these 424 patients were considered failures. The main causes of failure were lack of intraoperative communication with the patient (n = 18 [4.2%]) and/or intraoperative seizures (n = 9 [2.1%]). Preoperative mixed dysphasia (p < 0.001) and treatment with phenytoin (p = 0.0019) were related to failure due to lack of communication. History of seizures (p = 0.03) and treatment with multiple antiepileptic drugs (p = 0.0012) were found to be related to failure due to intraoperative seizures. Compared with the successful awake craniotomy group, a significantly lower rate of gross-total resection was achieved (83% vs 54%, p = 0.008), there was a higher incidence of short-term speech deterioration postoperatively (6.1% vs 23.5%, p = 0.0017) as well as at 3 months postoperatively (2.3% vs 15.4%, p = 0.0002), and the hospitalization period was longer (4.9 ± 6.2 days vs 8.0 ± 10.1 days, p < 0.001). Significantly more major complications occurred in the failure group (4 [14.8%] of 27) than in the successful group (16 [4%] of 397) (p = 0.037). Failures of awake craniotomy were associated with a lower incidence of gross-total resection and increased postoperative morbidity. The majority of awake craniotomy failures were preventable by adequate patient selection and avoiding side effects of drugs administered during surgery.

Failure Mechanisms and Evolution Assessment of the Excavation Damaged Zones in a Large-Scale and Deeply Buried Underground Powerhouse

NASA Astrophysics Data System (ADS)

Li, Hai-bo; Liu, Ming-chang; Xing, Wan-bo; Shao, Shuai; Zhou, Jia-wen

2017-07-01

The Jinping I underground powerhouse is deeply buried and is one of the largest underground powerhouses in China. As a result of high levels of in situ stress, complex geological conditions and the effects of excavation in adjacent caverns, the surrounding rock mass has been severely deformed and broken, and excavation damaged zones (EDZs) have become major obstacles to the design of cavern excavation and support. Field investigations and monitoring data indicated that there are two main modes of failure: high tangential stress induced failure and progressive failure, which have occurred on the mountain side and the river valley side of the Jinping I underground powerhouse. These two main modes of failure were due to strong secondary principal stress forces in the sub-parallel directions and sub-vertical directions, acting on the axes of the main powerhouse on the mountain side and on the river valley side, respectively. Deformations and EDZs on the river valley side were generally larger than those found along the mountain side, and the distribution of deformations was consistent with the distribution of EDZs. The evolution of the EDZ on the river valley side has clearly been time dependent, especially along the downstream arch abutment, and the EDZ was considerably enlarged with further excavation. Additionally, the deformation of the surrounding rock mass was first initiated from the edge of the excavation area and gradually extended to deeper areas away from the opening. However, the EDZ on the mountain side was enlarged only during the first two phases of excavation. The extension of pre-existing cracks and the creation of new fractures has mainly occurred in the oldest EDZ section, and the HDZ has been visibly enlarged, whereas the EDZ has shown little change in other excavation phases.

Otolaryngology head and neck surgery: an integrative view of the larynx.

PubMed

McCulloch, Timothy M; Van Daele, Douglas; Ciucci, Michelle R

2011-10-01

The glottis is composed of muscular, cartilaginous, and other viscoelastic tissues which perform some of our most important, complex, coordinated, and life-sustaining functions. Dominated by the thyroarytenoid muscles and associated glottic closure muscles, the larynx is involved in respiration, swallowing, voicing, coughing, valsalva, vomiting, laughing, and crying. With respiration continuing in the background, all other "secondary" laryngeal events seamlessly occur. When the delicate balance of coordinating these events is disrupted by disease or disorder, many of these tasks are compromised. Due to the complex innervation of these volitional and reflexive tasks with brainstem central pattern generators, primary sensorimotor areas and importantly, limbic areas, failure can occur due to disease, anatomic compromise, and even emotional state. Understanding the level of sensorimotor control and interaction among systems that share these laryngeal neuromuscular substrates will improve the diagnostic and therapeutic skill of the clinician when treating compromise of laryngeal function. Copyright © 2011 Wiley Periodicals, Inc.

Methodological issues in assessing changes in costs pre- and post-medication switch: a schizophrenia study example

PubMed Central

Faries, Douglas E; Nyhuis, Allen W; Ascher-Svanum, Haya

2009-01-01

Background Schizophrenia is a severe, chronic, and costly illness that adversely impacts patients' lives and health care payer budgets. Cost comparisons of treatment regimens are, therefore, important to health care payers and researchers. Pre-Post analyses ("mirror-image"), where outcomes prior to a medication switch are compared to outcomes post-switch, are commonly used in such research. However, medication changes often occur during a costly crisis event. Patients may relapse, be hospitalized, have a medication change, and then spend a period of time with intense use of costly resources (post-medication switch). While many advantages and disadvantages of Pre-Post methodology have been discussed, issues regarding the attributability of costs incurred around the time of medication switching have not been fully investigated. Methods Medical resource use data, including medications and acute-care services (hospitalizations, partial hospitalizations, emergency department) were collected for patients with schizophrenia who switched antipsychotics (n = 105) during a 1-year randomized, naturalistic, antipsychotic cost-effectiveness schizophrenia trial. Within-patient changes in total costs per day were computed during the pre- and post-medication change periods. In addition to the standard Pre-Post analysis comparing costs pre- and post-medication change, we investigated the sensitivity of results to varying assumptions regarding the attributability of acute care service costs occurring just after a medication switch that were likely due to initial medication failure. Results Fifty-six percent of all costs incurred during the first week on the newly initiated antipsychotic were likely due to treatment failure with the previous antipsychotic. Standard analyses suggested an average increase in cost-per-day for each patient of $2.40 after switching medications. However, sensitivity analyses removing costs incurred post-switch that were potentially due to the failure of the initial medication suggested decreases in costs in the range of $4.77 to $9.69 per day post-switch. Conclusion Pre-Post cost analyses are sensitive to the approach used to handle acute-service costs occurring just after a medication change. Given the importance of quality economic research on the cost of switching treatments, thorough sensitivity analyses should be performed to identify the impact of crisis events around the time of medication change. PMID:19473545

Computational Simulation of Damage Progression of Composite Thin Shells Subjected to Mechanical Loads

NASA Technical Reports Server (NTRS)

Gotsis, P. K.; Chamis, C. C.; Minnetyan, L.

1996-01-01

Defect-free and defected composite thin shells with ply orientation (90/0/+/-75) made of graphite/epoxy are simulated for damage progression and fracture due to internal pressure and axial loading. The thin shells have a cylindrical geometry with one end fixed and the other free. The applied load consists of an internal pressure in conjunction with an axial load at the free end, the cure temperature was 177 C (350 F) and the operational temperature was 21 C (70 F). The residual stresses due to the processing are taken into account. Shells with defect and without defects were examined by using CODSTRAN an integrated computer code that couples composite mechanics, finite element and account for all possible failure modes inherent in composites. CODSTRAN traces damage initiation, growth, accumulation, damage propagation and the final fracture of the structure. The results show that damage initiation started with matrix failure while damage/fracture progression occurred due to additional matrix failure and fiber fracture. The burst pressure of the (90/0/+/- 75) defected shell was 0.092% of that of the free defect. Finally the results of the damage progression of the (90/0/+/- 75), defective composite shell was compared with the (90/0/+/- theta, where theta = 45 and 60, layup configurations. It was shown that the examined laminate (90/0/+/- 75) has the least damage tolerant of the two compared defective shells with the (90/0/+/- theta), theta = 45 and 60 laminates.

Axillofemoral Bypass Markedly Improved Acute Decompensated Heart Failure and Kidney Injury in a Patient with Severely Calcified Stenosis of Thoracoabdominal Aorta (Atypical Aortic Coarctation).

PubMed

Ishizuka, Masato; Yamada, Shintaro; Maemura, Sonoko; Yamamoto, Keisuke; Takizawa, Masataka; Uozumi, Hiroki; Minegishi, Sachito; Kobayashi, Jotaro; Ikenouchi, Hiroshi

2017-10-21

Atypical aortic coarctation (AAC) has been reported to occur anywhere along the aorta, except for the ascending aorta. The associated symptoms include hypotension in the lower half of the body, secondary hypertension in the upper half of the body, and heart failure. Here we present an 80-year-old Asian woman complaining of progressive exertional dyspnea. She was diagnosed with acute decompensated heart failure and kidney injury due to severely calcified stenosis of the thoracoabdominal aorta, the so called AAC. She received hemodiafiltration, and pulmonary congestion improved in part. Generally, surgical treatments are quite invasive in elderly patients. Endovascular stent graft placement is less invasive, however, fracture and rupture should be considered at severely calcified lesions like this case. Therefore, we selected extra-anatomical axillofemoral bypass. Her recovery after the surgery was remarkable. In a few days, she became free from hemodiafiltration, intravenous diuretics, and oxygen administration. We thought the contributive factors are the increase in kidney blood flow and the correction of afterload mismatch. The decrease in pulse pressure may reflect the reduction in systemic arterial compliance by axillofemoral bypass. The operative mortality of axillofemoral bypass was reported to be acceptable, although the patency of the axillofemoral bypass graft was not high enough. In conclusion, axillofemoral bypass is effective and feasible for elderly patients with acute decompensated heart failure and kidney injury due to AAC.

Cardiomyocyte binucleation is associated with aberrant mitotic microtubule distribution, mislocalization of RhoA and IQGAP3, as well as defective actomyosin ring anchorage and cleavage furrow ingression.

PubMed

Leone, Marina; Musa, Gentian; Engel, Felix Benedikt

2018-03-07

After birth mammalian cardiomyocytes initiate a last cell cycle which results in binucleation due to cytokinesis failure. Despite its importance for cardiac regenerative therapies, this process is poorly understood. Here, we aimed at a better understanding of the difference between cardiomyocyte proliferation and binucleation, and providing a new tool to distinguish these two processes. Monitoring of cell division by time-lapse imaging revealed that rat cardiomyocyte binucleation stems from a failure to properly ingress the cleavage furrow. Astral microtubule required for actomyosin ring anchorage and thus furrow ingression were not symmetrically distributed at the periphery of the equatorial region during anaphase in binucleating cardiomyocytes. Consequently, RhoA, the master regulator of actomyosin ring formation and constriction, non-muscle myosin IIB, a central component of the actomyosin ring, as well as IQGAP3 were abnormally localized during cytokinesis. In agreement with improper furrow ingression, binucleation in vitro as well as in vivo was associated with a failure of RhoA as well as IQGAP3 to localize to the stembody of the midbody. Taken together, these results indicate that naturally occurring cytokinesis failure in primary cardiomyocytes is due to an aberrant mitotic microtubule apparatus resulting in inefficient anchorage of the actomyosin ring to the plasma cell membrane. Thus, cardiomyocyte binucleation and division can be discriminated by the analysis of RhoA as well as IQGAP3 localization.

[Traumatology in hang-gliding accidents. Studies based on 100 cases].

PubMed

Reymond, M A; de Gottrau, P; Fournier, P E; Arnold, T; Jacomet, H; Rigo, M

1988-11-01

The number of paragliding accidents is growing up exponentially. We review in this study 39 paragliding accidents which occurred 1985-1987 in the Val d'Illiez (Switzerland). The REGA (Swiss air ambulance) rescued 1987 61 pilots, which are also included. Most of the accidents were related to a mistake of the pilot. None is due to a failure of the material. The most severe injuries occurred immediately after taking off. The most frequent injuries occurred during landing. There is a correlation between the altitude, the wind velocity and the severity of the injuries. The lower extremities and the backbone are often injured, which is explained through the axial trauma. The pilots need a better training programme, the performance of the material should be built up and the starting places should be equipped.

Study of fracture toughness and bend test morphologies of HVOF sprayed Cr3C2-25% NiCr coating after heat treatment

NASA Astrophysics Data System (ADS)

Shrivastava, Sharad; Upadhyaya, Rohit

2018-04-01

Majority of the industrial components are subjected to high temperature exposure, where crack propagation occurs due to shear failure. The paper involves the study of the fracture toughness of heat treated Cr3C2-NiCr coating at three different service temperatures (750°C, 850°C, and 950°C for 1-hour aging) using indentation techniques to measure the crack resistance of the coating. At 750°C and 850°C, the coating cracked at the bend area, but not spalled. At 950°C, the coating spalled and delaminated from the substrate indicating poor adhesion after prolonged exposure. The influence of heat treatment on the fracture toughness and adhesion properties of the Cr3C2-25%NiCr coating were also investigated. The high temperature exposure at 950°C, resulted in a shear failure of the coating due to the presence of splat contraction. The increase in temperature increases the fracture toughness KIC of the coating, with the decrease in hardness. It was observed that the oxidation levels enhanced on the top layer of the coating, which acted like a core region for crack initiation at 950°C resulting in shear failure during bend test.

Design, Analysis and Testing of a PRSEUS Pressure Cube to Investigate Assembly Joints

NASA Technical Reports Server (NTRS)

Yovanof, Nicolette; Lovejoy, Andrew E.; Baraja, Jaime; Gould, Kevin

2012-01-01

Due to its potential to significantly increase fuel efficiency, the current focus of NASA's Environmentally Responsible Aviation Program is the hybrid wing body (HWB) aircraft. Due to the complex load condition that exists in HWB structure, as compared to traditional aircraft configurations, light-weight, cost-effective and manufacturable structural concepts are required to enable the HWB. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept is one such structural concept. A building block approach for technology development of the PRSEUS concept is being conducted. As part of this approach, a PRSEUS pressure cube was developed as a risk reduction test article to examine a new integral cap joint concept. This paper describes the design, analysis and testing of the PRSEUS pressure cube test article. The pressure cube was required to withstand a 2P, 18.4 psi, overpressure load requirement. The pristine pressure cube was tested to 2.2P with no catastrophic failure. After the addition of barely visible impact damage, the cube was pressure loaded to 48 psi where catastrophic failure occurred, meeting the scale-up requirement. Comparison of pretest and posttest analyses with the cube test response agree well, and indicate that current analysis methods can be used to accurately analyze PRSEUS structure for initial failure response.

Degradation phenomena of magnetic attachments used clinically in the oral environment

NASA Astrophysics Data System (ADS)

Chung, Chae-Heon; Choe, Han-Cheol; Kwak, Jong-Ha

2006-08-01

The purpose of this study was to investigate the mechanisms involved in the failure of magnetic attachments used to retain dental prostheses. Dyna magnets were retrieved from dentures that had failed after 34 months of clinical use. These magnetic attachments were prepared and sectioned so as to observe the corrosion surface and layer in order to analyze the corrosion behaviors of the attachments. The corroded surface was observed under a field emission scanning electron microscope (FE-SEM) (JSM 840A, JEOL, Japan). An X-ray diffractometer (XRD) was used to analyze the corrosion product formed due to corrosion in the oral environment. Erosion-corrosion started in the uneven portion of the stainless steel cover in the magnetic attachments composed with Nd-Fe-B alloy. Corrosion was initiated on the worn stainless steel surface, followed by spalling of magnetic material due to corrosive solution. The corrosion rate increased drastically after the corrosion product caused spalling in Nd-Fe-B alloy. Corrosion initiated in the uneven stainless steel surface as well as in the welded zone. In conclusion, the failure of magnetic attachments may occur by either welding failure or breakdown of the encapsulating material. Thus, we believe that treating the surface of magnetic attachments would resolve the corrosion problem seen in magnetic attachments to some extent.

Lymphatic Regeneration Within Porous VEGF-C Hydrogels for Secondary Lymphedema

DTIC Science & Technology

2004-07-01

A Lymphedema, however, strictly occurs when A B C swelling is due to a failure of lymph drainage in circumstances in which capillary filtration is not...increased. Figure 1: Schematic representation of Secondary Lymphedema. A) Normal lymphatic flow from the hand to the Thoracic duct (arrow). B ...of in vitro Proliferation and migration Assays of LEC in a Bodin chamber at 7 days. A) Ang-2 concentration of 0.22 jig/ml, B ) Ang-2 concentration of

Deaths from occlusive arterial disease in renal allograft recipients.

PubMed

Ibels, L S; Stewart, J H; Mahony, J F; Sheil, A G

1974-08-31

In a series of 325 recipients of cadaveric renal transplants sudden occlusive arterial disease was found to be responsible for 12% of deaths. Acute myocardial infarction (9%) occurred 25 times more than expected in the normal population and cerebral thrombosis (3%) 300 times more. The greatest loss was in the initial three-month period after transplantation. Patients with renal failure due to essential hypertension were especially at risk, accounting for six of the 12 deaths.

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.

“Risk factors associated with virologic failure in HIV-infected patients receiving antiretroviral therapy at a public hospital in Peru”

PubMed Central

Jorge, Alave R; Jorge, Paz B; Elsa, Gonzalez L; Miguel, Campos S; Rodriguez, Martin; Willig, James; Juan, Echevarría Z

2013-01-01

OBJECTIVE To describe clinical and biological characteristics of subjects with virologic failure who participated in the sexually transmitted diseases HIV/AIDS National Program from a Peruvian public hospital. MATERIALS AND METHODS An exploratory descriptive study was performed with data from subjects older than 18 who started high activity antiretroviral therapy (HAART) between May 2004 and December 2009 and who had a viral load control after 24 weeks of HAART. Virologic failure was defined as a viral load value above 1000 copies/mL on follow up after 24 weeks on HAART. RESULTS Of 1 478 records of patients on HAART analized, the median age was 35 years [IQR, 29-41] and 69.6% were male. Also, virologic failure occurred in 24% and 3.7% died. Of subjects with virologic failure, 9.5% died. On multivariate analysis, age, history of antiretroviral use before starting HAART, change of antiretroviral therapy due to toxicity, opportunistic infections during HAART, level of CD4 + lymphocytes below 100 cells/ml at start of HAART, adherence and clinical stage were independently associated with virologic failure. In the group of patient with no history of antiretroviral use before starting HAART, age, opportunistic infections during HAART were associated with virologic failure. CONCLUSION This study identified factors associated with virologic failure. Further studies are needed to evaluate whether the use of these factors can help to identify prospectively patients at high risk of failure, and to design interventions aimed to reduce this risk. PMID:23450408

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.

Effect of Joule heating and current crowding on electromigration in mobile technology

NASA Astrophysics Data System (ADS)

Tu, K. N.; Liu, Yingxia; Li, Menglu

2017-03-01

In the present era of big data and internet of things, the use of microelectronic products in all aspects of our life is manifested by the ubiquitous presence of mobile devices as i-phones and wearable i-products. These devices are facing the need for higher power and greater functionality applications such as in i-health, yet they are limited by physical size. At the moment, software (Apps) is much ahead of hardware in mobile technology. To advance hardware, the end of Moore's law in two-dimensional integrated circuits can be extended by three-dimensional integrated circuits (3D ICs). The concept of 3D ICs has been with us for more than ten years. The challenge in 3D IC technology is dense packing by using both vertical and horizontal interconnections. Mass production of 3D IC devices is behind schedule due to cost because of low yield and uncertain reliability. Joule heating is serious in a dense structure because of heat generation and dissipation. A change of reliability paradigm has advanced from failure at a specific circuit component to failure at a system level weak-link. Currently, the electronic industry is introducing 3D IC devices in mainframe computers, where cost is not an issue, for the purpose of collecting field data of failure, especially the effect of Joule heating and current crowding on electromigration. This review will concentrate on the positive feedback between Joule heating and electromigration, resulting in an accelerated system level weak-link failure. A new driving force of electromigration, the electric potential gradient force due to current crowding, will be reviewed critically. The induced failure tends to occur in the low current density region.

Identification and Classification of Mass Transport Complexes in Offshore Trinidad/Venezuela and Their Potential Anthropogenic Impact as Tsunamigenic Hazards

NASA Astrophysics Data System (ADS)

Moscardelli, L.; Wood, L. J.

2006-12-01

Several late Pleistocene-age seafloor destabilization events have been identified in the continental margin of eastern offshore Trinidad, of sufficient scale to produce tsunamigenic forces. This area, situated along the obliquely-converging-boundary of the Caribbean/South American plates and proximal to the Orinoco Delta, is characterized by catastrophic shelf-margin processes, intrusive-extrusive mobile shales, and active tectonism. A mega-merged, 10,000km2, 3D seismic survey reveals several mass transport complexes that range in area from 11.3km2 to 2017km2. Historical records indicate that this region has experienced submarine landslide- generated tsunamigenic events, including tsunamis that affected Venezuela during the 1700's-1900's. This work concentrates on defining those ancient deep marine mass transport complexes whose occurrence could potentially triggered tsunamis. Three types of failures are identified; 1) source-attached failures that are fed by shelf edge deltas whose sediment input is controlled by sea-level fluctuations and sedimentation rates, 2) source-detached systems, which occur when upper slope sediments catastrophically fail due to gas hydrate disruptions and/or earthquakes, and 3) locally sourced failures, formed when local instabilities in the sea floor trigger relatively smaller collapses. Such classification of the relationship between slope mass failures and the sourcing regions enables a better understanding of the nature of initiation, length of development history and petrography of such mass transport deposits. Source-detached systems, generated due to sudden sediment remobilizations, are more likely to disrupt the overlying water column causing a rise in tsunamigenic risk. Unlike 2D seismic, 3D seismic enables scientists to calculate more accurate deposit volumes, improve deposit imaging and thus increase the accuracy of physical and computer simulations of mass failure processes.

Slope failures in municipal solid waste dumps and landfills: a review.

PubMed

Blight, Geoffrey

2008-10-01

Between 1977 and 2005 six large-scale failures of municipal solid waste dumps and landfills have been recorded in the technical literature. The volumes of waste mobilized in the failures varied from 10-12 000 m(3) in a failure that killed nearly 300 people to 1.5 million m(3) in a failure that caused no deaths or injuries. Of the six failures, four occurred in dumps that, as far as is known, had not been subjected to any prior technical investigation of their shear stability. The remaining two failures occurred in engineer-designed landfills, one of which practised leachate recirculation, and the other co-disposed of liquid waste along with solid waste. The paper reviews, describes and analyses the failures and summarizes their causes.

FEMA and RAM Analysis for the Multi Canister Overpack (MCO) Handling Machine

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

SWENSON, C.E.

2000-06-01

The Failure Modes and Effects Analysis and the Reliability, Availability, and Maintainability Analysis performed for the Multi-Canister Overpack Handling Machine (MHM) has shown that the current design provides for a safe system, but the reliability of the system (primarily due to the complexity of the interlocks and permissive controls) is relatively low. No specific failure modes were identified where significant consequences to the public occurred, or where significant impact to nearby workers should be expected. The overall reliability calculation for the MHM shows a 98.1 percent probability of operating for eight hours without failure, and an availability of the MHMmore » of 90 percent. The majority of the reliability issues are found in the interlocks and controls. The availability of appropriate spare parts and maintenance personnel, coupled with well written operating procedures, will play a more important role in successful mission completion for the MHM than other less complicated systems.« less

Progressive Fracture of Fiber Composite Thin Shell Structures Under Internal Pressure and Axial Loads

NASA Technical Reports Server (NTRS)

Gotsis, Pascal K.; Chamis, Christos C.; Minnetyan, Levon

1996-01-01

Graphite/epoxy composite thin shell structures were simulated to investigate damage and fracture progression due to internal pressure and axial loading. Defective and defect-free structures (thin cylinders) were examined. The three different laminates examined had fiber orientations of (90/0/+/-0)(sub s), where 0 is 45, 60, and 75 deg. CODSTRAN, an integrated computer code that scales up constituent level properties to the structural level and accounts for all possible failure modes, was used to simulate composite degradation under loading. Damage initiation, growth, accumulation, and propagation to fracture were included in the simulation. Burst pressures for defective and defect-free shells were compared to evaluate damage tolerance. The results showed that damage initiation began with matrix failure whereas damage and/or fracture progression occurred as a result of additional matrix failure and fiber fracture. In both thin cylinder cases examined (defective and defect-free), the optimum layup configuration was (90/0/+/-60)(sub s) because it had the best damage tolerance with respect to the burst pressure.

Endurance tests with large-bore tapered-roller bearings to 2.2 million DN

NASA Technical Reports Server (NTRS)

Parker, R. J.; Signer, H. R.; Pinel, S. I.

1981-01-01

Endurance life tests were run with standard design and optimized high-speed design 120.65-mm-(4.750-in.-) bore tapered-roller bearings at shaft speeds of 12,500 and 18,500 rpm, respectively. Standard design bearings of vacuum melted AISI 4320 and CBS-1000M, and high-speed design bearings of CBS-1000M and through-hardened AISI M-50 were run under heavy combined radial and thrust load until fatigue failure or until a preset cutoff time of 1100 hours was reached. Standard design bearings made from CBS 1000M material ran to a 10 percent life approximately six times rated catalog life. Twelve identical bearings of AISI 4320 material ran to ten times rated catalog life without failure. Cracking and fracture of the cones of AISI M-50 high-speed design bearings occurred at 18,500 rpm due to high tensile hoop stresses. Four CBS 1000M high-speed design bearings ran to twenty-four times rated catalog life without any spalling, cracking or fracture failures.

Biodegradable Magnesium (Mg) Implantation Does Not Impose Related Metabolic Disorders in Rats with Chronic Renal Failure

PubMed Central

Wang, Jiali; Xu, Jiankun; Liu, Waiching; Li, Yangde; Qin, Ling

2016-01-01

Mg and its alloys have been considered as one of the most promising biodegradable medical devices, but it was still unclear whether hypermagnesemia involved health risks would occur in persons with kidney disease due to their deteriorated kidney function for Mg ions excretion from their body. In this study, we established a chronic renal failure (CRF) model in rats induced by adenine administration prior to Mg implantation, aiming to predict if CRF patients are suitable for the use of Mg implants. The results showed that Mg levels in serum, urine, feces and internal organs had no significant changes after Mg implantation for both normal and CRF rats. Biochemical indices detection and histopathological analysis in kidney, liver and heart tissue confirmed that Mg implants did not induce any extra damage in animals even with renal failure. Our study indicates that Mg based orthopaedic medical device may be considered for use in CRF patients without biosafety concerns. PMID:27210744

Biodegradable Magnesium (Mg) Implantation Does Not Impose Related Metabolic Disorders in Rats with Chronic Renal Failure

NASA Astrophysics Data System (ADS)

Wang, Jiali; Xu, Jiankun; Liu, Waiching; Li, Yangde; Qin, Ling

2016-05-01

Mg and its alloys have been considered as one of the most promising biodegradable medical devices, but it was still unclear whether hypermagnesemia involved health risks would occur in persons with kidney disease due to their deteriorated kidney function for Mg ions excretion from their body. In this study, we established a chronic renal failure (CRF) model in rats induced by adenine administration prior to Mg implantation, aiming to predict if CRF patients are suitable for the use of Mg implants. The results showed that Mg levels in serum, urine, feces and internal organs had no significant changes after Mg implantation for both normal and CRF rats. Biochemical indices detection and histopathological analysis in kidney, liver and heart tissue confirmed that Mg implants did not induce any extra damage in animals even with renal failure. Our study indicates that Mg based orthopaedic medical device may be considered for use in CRF patients without biosafety concerns.

Failure Mechanisms of Ni-H2 and Li-Ion Batteries Under Hypervelocity Impacts

NASA Technical Reports Server (NTRS)

Miller, J. E.; Lyons, F.; Christiansen, E. L.; Lear, D. M.

2017-01-01

Lithium-Ion (Li-Ion) batteries have yielded significant performance advantages for many industries, including the aerospace industry, and have been selected to replace nickel hydrogen (Ni-H2) batteries for the International Space Station (ISS) program to meet the energy storage demands. As the ISS uses its vast solar arrays to generate its power, the solar arrays meet their sunlit power demands and supply excess power to battery packs for power delivery on the sun obscured phase of the approximate 90 minute low Earth orbit. These large battery packs are located on the exterior of the ISS, and as such, the battery packs are exposed to external environment threats like naturally occurring meteoroids and artificial orbital debris (MMOD). While the risks from these solid particle environments has been known and addressed to an acceptable risk of failure through shield design, it is not possible to completely eliminate the risk of loss of these assets on orbit due to MMOD, and as such, failure consequences to the ISS have been considered.

Stormwater Volume Control to Prevent Increases in Lake Flooding and Dam Failure Risk

NASA Astrophysics Data System (ADS)

Potter, K. W.

2017-12-01

Urban expansion is not often considered a major factor contributing to dam failure. But if urbanization occurs without mitigation of the hydrologic impacts, the risk of dam failure will increase. Of particular concern are increases in the volume of storm runoff resulting from increases in the extent of impervious surfaces. Storm runoff volumes are not regulated for much the U.S, and where they are, the required control is commonly less than 100%. Unmitigated increases in runoff volume due to urbanization can pose a risk to dams. A recent technical advisory committee of Dane County has recommended that the county require 100% control of stormwater volumes for new developments. The primary motivation was to prevent increases in the water levels in the Yahara Lakes, slowly draining lakes that are highly sensitive to runoff volume. The recommendations included the use of "volume trading" to achieve efficient compliance. Such recommendations should be considered for other slowly draining lakes, including those created by artificial structures.

[Primary systemic amyloidosis].

PubMed

Tanasilović, Srdan; Zivanović, Dubravka; Nikolić, Milos; Tomović, Maja; Elezović, Ivo; Medenica, Ljiljana

2007-12-01

Systemic amyloidosis is a rare disorder which usually occurs in aged persons and has a poor prognosis. Systemic amyloidosis can be primary, occasionally associated with multiple myeloma, or secondary, associated with another disease. We presented a 72-year-old male patient with periocular purpura ("racoon sign") and waxy papules, petechiae and ecchymoses on the neck and thoracic area. Purpuric macules were present also on the lips and tongue which was edematous (macroglossia). The skin lesions occurred two years earlier, the patient lost more than 15 kilograms of the body mass for less than a year. Immunoelectrophoresis of urine and serum demonstrated the presence of immunoglobulin light chains of the circulating monoclonal protein. Histopathological examination of skin lesions showed Congo red positive deposits in the derm. Cardiac evaluation revealed the signs of heart failure, and renal evaluation revealed nephrotic syndrome, with excessive protein lost. He was treated with oral melphalan and prednisolone, and died 7 days after starting the therapy due to heart failure. This patient considered as a rare case with systemic amyloidosis highlights the importance of histopathological and physical examination in any cases with periocular purpura, petechiae, ecchymoses and macroglossia.

Cost of a recall of a single-center experience managing the Riata defibrillator lead.

PubMed

Hussain, Sarah; Moorman, Liza; Moorman, J Randall; DiMarco, John P; Malhotra, Rohit; Darby, Andrew; Bilchick, Kenneth; Mangrum, J Michael; Ferguson, John D; Mason, Pamela K

2015-01-15

Riata and Riata ST defibrillator leads (St. Jude Medical, Sylmar, California) were recalled in 2011 due to increased risk of insulation failure leading to externalized cables. Fluoroscopic screening can identify insulation failure, although the relation between mechanical failure and electrical failure is unclear. At the time of the recall, the University of Virginia developed a screening program, including fluoroscopic evaluation, education sessions, device interrogation, and remote monitoring for patients with this defibrillator lead. The aim of this study was to review the outcomes of the screening program, including costs, which were absorbed by our institution. Costs were calculated using Medicare reimbursement estimates. Forty-eight patients participated in the screening program. At initial screening, 31% were found to have evidence of insulation failure but electrical function was normal in all leads. The cost of this program was $35,358.72. The cost per diagnosis of mechanical lead failure was $2,357.25. During 2 years of follow-up, 1 patient experienced Riata lead electrical failure without fluoroscopic evidence of insulation failure. Patients were more likely to have a lead revision if there was evidence of insulation failure. Lead revisions occurred at the time of generator change in 88% of patients with insulation failure but in only 14% of patients with a fluoroscopically normal lead (p = 0.04). The cost of recall-related defibrillator lead revisions was $81,704.55. In conclusion, our Riata screening program added expense without clear benefit to patients. In fact, patients may have been put at more risk by undergoing defibrillator lead revisions based solely on the results of the fluoroscopic screening. Copyright © 2015 Elsevier Inc. All rights reserved.

Orbiter Payload Bay Bucket Hoist Mishap...An Accident We Should Never Forget

NASA Technical Reports Server (NTRS)

Lytle, Bradford P.

2009-01-01

This slide presentation reviews the accident that occurred in 1985 when a bay bucket hoist fell from its stowed position. This accident damaged the orbiter, injured a technician, and delayed the launch. The accident was investigated, and the cause of the accident was determined to be the practice of two-blocking. Two-blocking is the result of hoisting beyond the intended safe upper limit of hook travel to the point of solid contact between the load block and the upper block or hoist/trolley structure. The usual result is immediate failure of the wire rope, due to the ropes being cut by the grooves of the drum or sheaves. The design of the hoist, the inspection, and the operator training were all in part responsible for this failure.

Reliability Analysis of Uniaxially Ground Brittle Materials

NASA Technical Reports Server (NTRS)

Salem, Jonathan A.; Nemeth, Noel N.; Powers, Lynn M.; Choi, Sung R.

1995-01-01

The fast fracture strength distribution of uniaxially ground, alpha silicon carbide was investigated as a function of grinding angle relative to the principal stress direction in flexure. Both as-ground and ground/annealed surfaces were investigated. The resulting flexural strength distributions were used to verify reliability models and predict the strength distribution of larger plate specimens tested in biaxial flexure. Complete fractography was done on the specimens. Failures occurred from agglomerates, machining cracks, or hybrid flaws that consisted of a machining crack located at a processing agglomerate. Annealing eliminated failures due to machining damage. Reliability analyses were performed using two and three parameter Weibull and Batdorf methodologies. The Weibull size effect was demonstrated for machining flaws. Mixed mode reliability models reasonably predicted the strength distributions of uniaxial flexure and biaxial plate specimens.

Giant and thrombosed left ventricular aneurysm

PubMed Central

de Agustin, Jose Alberto; de Diego, Jose Juan Gomez; Marcos-Alberca, Pedro; Rodrigo, Jose Luis; Almeria, Carlos; Mahia, Patricia; Luaces, Maria; Garcia-Fernandez, Miguel Angel; Macaya, Carlos; de Isla, Leopoldo Perez

2015-01-01

Left ventricular aneurysms are a frequent complication of acute extensive myocardial infarction and are most commonly located at the ventricular apex. A timely diagnosis is vital due to the serious complications that can occur, including heart failure, thromboembolism, or tachyarrhythmias. We report the case of a 78-year-old male with history of previous anterior myocardial infarction and currently under evaluation by chronic heart failure. Transthoracic echocardiogram revealed a huge thrombosed and calcified anteroapical left ventricular aneurysm. Coronary angiography demonstrated that the left anterior descending artery was chronically occluded, and revealed a big and spherical mass with calcified borders in the left hemithorax. Left ventriculogram confirmed that this spherical mass was a giant calcified left ventricular aneurysm, causing very severe left ventricular systolic dysfunction. The patient underwent cardioverter-defibrillator implantation for primary prevention. PMID:26225205

Treatment preferences and outcome in male hypogonadotropic hypogonadism: an Indian perspective.

PubMed

Sanyal, D; Chatterjee, S

2016-06-01

This retrospective study assessed treatment preferences and outcome with testosterone or HCG / HCG-FSH combination in Indian male idiopathic hypogonadotropic hypogonadism (IHH) subjects (n = 31) above 18 years of age. 38.7% of IHH study subjects had no fertility plans and chose 3 monthly intramuscular testosterone undecanoate. 73.7% of subjects with fertility plans chose human chorionic gonadotropin (HCG) alone due to cost considerations. Spermatogenesis occurred in 21.4% on HCG alone and 60% of subjects on HCG with follicle-stimulating hormone (FSH) combination. Treatment failure is higher than published Western rates. FSH and HCG combination regimen is costly but superior to HCG alone. However, treatment failure still persists, suggesting unknown testicular defect in IHH. © 2015 Blackwell Verlag GmbH.

Cellular alterations and enhanced induction of cleft palate after coadministration of retinoic acid and TCDD

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

Abbott, B.D.; Birnbaum, L.S.

1989-06-15

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and retinoic acid (RA) are both teratogenic in mice. TCDD is a highly toxic, stable environmental contaminant, while RA is a naturally occurring form of vitamin A. Exposure to TCDD induces hydronephrosis and cleft palate, and exposure to RA induces limb defects and cleft palate. Teratology studies previously have shown that the incidence of clefting is higher after exposure to RA + TCDD than would be observed for the same doses of either compound given alone. This study examines the cellular effects which result in cleft palate, after po administration on gestation Day (GD) 10 or 12 ofmore » RA + TCDD in corn oil (10 ml/kg total volume). Exposure on GD 10 to 6 micrograms TCDD + 40 mg RA/kg inhibited early growth of the shelves and clefting was due to a failure of shelves to meet and fuse. This effect on mesenchyme was observed in previous studies to occur after exposure on GD 10 to 40 mg/kg RA alone, but not after TCDD alone. After exposure on GD 12 to 6 micrograms TCDD + 80 mg RA/kg, clefting was due to a failure of shelves to fuse after making contact, because the medial cells differentiated into an oral-like epithelium. This response was observed in previous studies to occur after exposure to TCDD alone, but RA alone on GD 12 resulted in differentiation toward nasal-like cells. The interaction between TCDD and RA results in RA-like clefting after exposure on GD 10 and TCDD-like clefting after exposure on GD 12, and this clefting occurs at higher incidences than would occur after the same levels of either agent alone. After exposure on either GD 10 or 12 to RA + TCDD, the programmed cell death of the medial cells does not occur, and these cells continue to express EGF receptors and to bind 125I-EGF. The effects of RA and TCDD may involve modulation of the cells responses to embryonic growth and differentiation factors.« less

Characterization of interfacial failure in SiC reinforced Si3N4 matrix composite material by both fiber push-out testing and Auger electron spectroscopy

NASA Technical Reports Server (NTRS)

Eldridge, J. I.; Honecy, F. S.

1990-01-01

AES depth profiling and a fiber push-out test for interfacial shear-strength determination have been used to ascertain the mechanical/chemical properties of the fiber/matrix interface in SiC-reinforced reaction-bonded Si3N4, with attention to the weak point where interfacial failure occurs. In the cases of both composite fracture and fiber push-outs, the interfacial failure occurred either between the two C-rich coatings that are present on the double-coated SiC fibers, or between the inner C-rich coating and the SiC fiber. Interface failure occurs at points of very abrupt concentration changes.

Salmon as a food-poisoning vehicle--two successive Salmonella outbreaks.

PubMed Central

Cartwright, K. A.; Evans, B. G.

1988-01-01

Gastroenteritis due to Salmonella montevideo occurred amongst guests attending two social functions held within 24 h, food for both having been provided by the same catering firm. Salmon was the most likely vehicle of infection in each case, although cross-contamination of other foods occurred. There were no deaths; four patients were admitted to hospital, one of whom underwent appendicectomy. A review of salmon-associated food-poisoning outbreaks suggests that fresh salmon is an infrequent cause of food poisoning in the United Kingdom. The two outbreaks described here resulted from a failure of simple kitchen hygiene measures at a time of high ambient temperatures. Some current cooking instructions for salmon are inadequate. PMID:3181309

A New Approach to Fibrous Composite Laminate Strength Prediction

NASA Technical Reports Server (NTRS)

Hart-Smith, L. J.

1990-01-01

A method of predicting the strength of cross-plied fibrous composite laminates is based on expressing the classical maximum-shear-stress failure criterion for ductile metals in terms of strains. Starting with such a formulation for classical isotropic materials, the derivation is extended to orthotropic materials having a longitudinal axis of symmetry, to represent the fibers in a unidirectional composite lamina. The only modification needed to represent those same fibers with properties normalized to the lamina rather than fiber is a change in axial modulus. A mirror image is added to the strain-based lamina failure criterion for fiber-dominated failures to reflect the cutoffs due to the presence of orthogonal fibers. It is found that the combined failure envelope is now identical with the well-known maximum-strain failure model in the tension-tension and compression-compression quadrants but is truncated in the shear quadrants. The successive application of this simple failure model for fibers in the 0/90 degree and +/- 45 degree orientations, in turn, is shown to be the necessary and sufficient characterization of the fiber-dominated failures of laminates made from fibers having the same tensile and compressive strengths. When one such strength is greater than the other, the failure envelope is appropriately truncated for the lesser direct strain. The shear-failure cutoffs are now based on the higher axial strain to failure since they occur at lower strains than and are usually not affected by such mechanisms as microbuckling. Premature matrix failures can also be covered by appropriately truncating the fiber failure envelope. Matrix failures are excluded from consideration for conventional fiber/polymer composites but the additional features needed for a more rigorous analysis of exotic materials are covered. The new failure envelope is compared with published biaxial test data. The theory is developed for unnotched laminates but is easily shrunk to incorporate reductions to allow for bolt holes, cutouts, reduced compressive strength after impact, and the like.

Factors Influencing the Effectiveness of Glucagon for Preventing Hypoglycemia

PubMed Central

Castle, Jessica R; Engle, Julia M; El Youssef, Joseph; Massoud, Ryan G; Ward, W Kenneth

2010-01-01

Background Administration of small, intermittent doses of glucagon during closed-loop insulin delivery markedly reduces the frequency of hypoglycemia. However, in some cases, hypoglycemia occurs despite administration of glucagon in this setting. Methods Fourteen adult subjects with type 1 diabetes participated in 22 closed-loop studies, duration 21.5 ± 2.0 h. The majority of subjects completed two studies, one with insulin + glucagon, given subcutaneously by algorithm during impending hypoglycemia, and one with insulin + placebo. The more accurate of two subcutaneous glucose sensors was used as the controller input. To better understand reasons for success or failure of glucagon to prevent hypoglycemia, each response to a glucagon dose over 0.5 µg/kg was analyzed (n = 19 episodes). Results Hypoglycemia occurred in the hour after glucagon delivery in 37% of these episodes. In the failures, estimated insulin on board was significantly higher versus successes (5.8 ± 0.5 versus 2.9 ± 0.5 U, p < .001). Glucose at the time of glucagon delivery was significantly lower in failures versus successes (86 ± 3 versus 95 ± 3 mg/dl, p = .04). Sensor bias (glucose overestimation) was highly correlated with starting glucose (r = 0.65, p = .002). Prior cumulative glucagon dose was not associated with success or failure. Conclusion Glucagon may fail to prevent hypoglycemia when insulin on board is high or when glucagon delivery is delayed due to overestimation of glucose by the sensor. Improvements in sensor accuracy and delivery of larger or earlier glucagon doses when insulin on board is high may further reduce the frequency of hypoglycemia. PMID:21129324

Factors influencing the effectiveness of glucagon for preventing hypoglycemia.

PubMed

Castle, Jessica R; Engle, Julia M; El Youssef, Joseph; Massoud, Ryan G; Ward, W Kenneth

2010-11-01

Administration of small, intermittent doses of glucagon during closed-loop insulin delivery markedly reduces the frequency of hypoglycemia. However, in some cases, hypoglycemia occurs despite administration of glucagon in this setting. Fourteen adult subjects with type 1 diabetes participated in 22 closed-loop studies, duration 21.5±2.0 h. The majority of subjects completed two studies, one with insulin + glucagon, given subcutaneously by algorithm during impending hypoglycemia, and one with insulin+placebo. The more accurate of two subcutaneous glucose sensors was used as the controller input. To better understand reasons for success or failure of glucagon to prevent hypoglycemia, each response to a glucagon dose over 0.5 µg/kg was analyzed (n=19 episodes). Hypoglycemia occurred in the hour after glucagon delivery in 37% of these episodes. In the failures, estimated insulin on board was significantly higher versus successes (5.8±0.5 versus 2.9±0.5 U, p<.001). Glucose at the time of glucagon delivery was significantly lower in failures versus successes (86±3 versus 95±3 mg/dl, p=.04). Sensor bias (glucose overestimation) was highly correlated with starting glucose (r=0.65, p=.002). Prior cumulative glucagon dose was not associated with success or failure. Glucagon may fail to prevent hypoglycemia when insulin on board is high or when glucagon delivery is delayed due to overestimation of glucose by the sensor. Improvements in sensor accuracy and delivery of larger or earlier glucagon doses when insulin on board is high may further reduce the frequency of hypoglycemia. © 2010 Diabetes Technology Society.

Managing a Multisite Academic-Private Radiology Practice Reading Environment: Impact of IT Downtimes on Enterprise Efficiency.

PubMed

Becker, Murray; Goldszal, Alberto; Detal, Julie; Gronlund-Jacob, Judith; Epstein, Robert

2015-06-01

The aim of this study was to assess whether the complex radiology IT infrastructures needed for large, geographically diversified, radiology practices are inherently stable with respect to system downtimes, and to characterize the nature of the downtimes to better understand their impact on radiology department workflow. All radiology IT unplanned downtimes over a 12-month period in a hybrid academic-private practice that performs all interpretations in-house (no commercial "nighthawk" services) for approximately 900,000 studies per year, originating at 6 hospitals, 10 outpatient imaging centers, and multiple low-volume off-hours sites, were logged and characterized using 5 downtime metrics: duration, etiology, failure type, extent, and severity. In 12 consecutive months, 117 unplanned downtimes occurred with the following characteristics: duration: median time = 3.5 hours with 34% <1.5 hours and 30% >12 hours; etiology: 87% were due to software malfunctions, and 13% to hardware malfunctions; failure type: 88% were transient component failures, 12% were complete component failures; extent: all sites experienced downtimes, but downtimes were always localized to a subset of sites, and no system-wide downtimes occurred; severity (impact on radiologist workflow): 47% had minimal impact, 50% moderate impact, and 3% severe impact. In the complex radiology IT system that was studied, downtimes were common; they were usually a result of transient software malfunctions; the geographic extent was always localized rather than system wide; and most often, the impacts on radiologist workflow were modest. Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Removal of a broken trigen intertan intertrochanteric antegrade nail.

PubMed

Zheng, Xuan-Lin; Park, Young-Chang; Kim, Sungmin; An, Haemosu; Yang, Kyu-Hyun

2017-02-01

Implant breakage is a serious complication after cephalomedullary nailing for unstable intertrochanteric fracture. Failure usually occurs at the lag screw hole in the nail body. On the other hand, lag screw failure is extremely rare and occurs around the nail-lag screw junction. We experienced rare mechanical failure of the Intertan nail, which showed breakage at the lag screw hole and failure of the integrated compression screw underneath the main lag screw. Copyright © 2016 Elsevier Ltd. All rights reserved.

Program Helps In Analysis Of Failures

NASA Technical Reports Server (NTRS)

Stevenson, R. W.; Austin, M. E.; Miller, J. G.

1993-01-01

Failure Environment Analysis Tool (FEAT) computer program developed to enable people to see and better understand effects of failures in system. User selects failures from either engineering schematic diagrams or digraph-model graphics, and effects or potential causes of failures highlighted in color on same schematic-diagram or digraph representation. Uses digraph models to answer two questions: What will happen to system if set of failure events occurs? and What are possible causes of set of selected failures? Helps design reviewers understand exactly what redundancies built into system and where there is need to protect weak parts of system or remove them by redesign. Program also useful in operations, where it helps identify causes of failure after they occur. FEAT reduces costs of evaluation of designs, training, and learning how failures propagate through system. Written using Macintosh Programmers Workshop C v3.1. Can be linked with CLIPS 5.0 (MSC-21927, available from COSMIC).

Urban Landslides Induced by the 2004 Niigata-Chuetsu Earthquake

NASA Astrophysics Data System (ADS)

Kamai, T.; Trandafir, A. C.; Sidle, R. C.

2005-05-01

Landslides triggered by the Chuetsu earthquake occurred in artificial slopes of some new developments in suburban Nagaoka, the largest city in the affected area. The landslides occurred in hilly terrain of the eastern part of Nagaoka between the alluvial plain and Tertiary folded mountains of Yamakoshi. Although the extent of landslides in urban Nagaoka was small compared with landslides on natural slopes (especially near Yamakoshi), they represent an important case study for urban landslide disasters. Slope instabilities in urban residential areas were classified as: A) landslides in steep embankments; B) landslides in gently sloping artificial valley fills; C) re-activation of old landslides; and D) liquefaction in deep artificial valley fills. All these failures occurred in relatively uniform suburban landscapes, which were significantly modified from the original landforms. Recent destructive earthquakes in Japan caused similar types of slope failures in urban regions, suggesting that lessons from past earthquakes were not implemented. The greatest damage due to type-A failures occurred in the 25-yr old Takamachi residential area, where about 70 of 522 homes were judged to be uninhabitable. Before development, this area was an isolated hill (90 m elevation) with an adjacent terrace (60 m elevation) consisting of gravel, sand, and silt of the lower to middle Pleistocene deposits. Development earthworks removed the hill crest and created a wide plateau (70 m elevation); excavated soil was placed on the perimeter as an embankment. During the earthquake, the embankment slope collapsed, including retaining walls, perimeter road, and homes. The most serious damage occurred in five places around the margin of the plateau corresponding to shallow valley fills (5 to 8 m thick). Earthquake response analyses using an equivalent linear model indicated the amplification of seismic waves at the surface of embankment slopes, and the peak earthquake acceleration exceeded 1 G in the case of embankment thicknesses <8 m. The natural frequency at the shoulder of embankment slopes is inversely proportion to fill thickness; less than the predominant frequency of the earthquake (3 Hz). Shallow embankments were unstable compared to deeper embankments because their natural frequency was close to the predominant frequency of the earthquake. Thus, we expect widespread embankment failures in megacities during the next giant earthquake shaking with low predominant frequency originating offshore of the Pacific Ocean.

Flotation and Survival Equipment Studies

DTIC Science & Technology

1978-01-01

the hearing of Lhe latter ditching that he saw no reason to have expected any loss of life with the two exceptions that did occur: failure of life...jackets to inflate and loss of six infants. It is the purpose of this paper to examine the requirements of infant and small-child flotation devices and...surface area immersed, one may crudely estimate the heat loss due to Newtonian cooling at 3 kcal per °C. The total basal heat productivity of a 2

[Haemophilus influenzae type b meningitis in a vaccinated, immunocompetent infant with reactive arthritis].

PubMed

Nystrup, Kristin Brønnum; Wilms, Line Kønig

2015-01-26

Due to the excellent immunogenicity of the Haemophilus influenzae type b (Hib) conjugate vaccines, vaccine failures are rarely seen in patients following the recommended national immunization programmes. We present an infant with Hib meningitis despite relevant prophylaxis, without known risk factors such as medical co-morbidity, immunosuppression, immunoglobulin deficiency or prematurity. Later, a reactive arthritis developed. In conclusion, Hib-meningitis can occur in vaccinated, immunocompetent patients, and antibiotics covering Hib should be chosen in patients presenting with meningitis.

Assessment of the risk of failure of high voltage substations due to environmental conditions and pollution on insulators.

PubMed

Castillo Sierra, Rafael; Oviedo-Trespalacios, Oscar; Candelo, John E; Soto, Jose D

2015-07-01

Pollution on electrical insulators is one of the greatest causes of failure of substations subjected to high levels of salinity and environmental pollution. Considering leakage current as the main indicator of pollution on insulators, this paper focuses on establishing the effect of the environmental conditions on the risk of failure due to pollution on insulators and determining the significant change in the magnitude of the pollution on the insulators during dry and humid periods. Hierarchical segmentation analysis was used to establish the effect of environmental conditions on the risk of failure due to pollution on insulators. The Kruskal-Wallis test was utilized to determine the significant changes in the magnitude of the pollution due to climate periods. An important result was the discovery that leakage current was more common on insulators during dry periods than humid ones. There was also a higher risk of failure due to pollution during dry periods. During the humid period, various temperatures and wind directions produced a small change in the risk of failure. As a technical result, operators of electrical substations can now identify the cause of an increase in risk of failure due to pollution in the area. The research provides a contribution towards the behaviour of the leakage current under conditions similar to those of the Colombian Caribbean coast and how they affect the risk of failure of the substation due to pollution.

Accidental Water Pollution Risk Analysis of Mine Tailings Ponds in Guanting Reservoir Watershed, Zhangjiakou City, China.

PubMed

Liu, Renzhi; Liu, Jing; Zhang, Zhijiao; Borthwick, Alistair; Zhang, Ke

2015-12-02

Over the past half century, a surprising number of major pollution incidents occurred due to tailings dam failures. Most previous studies of such incidents comprised forensic analyses of environmental impacts after a tailings dam failure, with few considering the combined pollution risk before incidents occur at a watershed-scale. We therefore propose Watershed-scale Tailings-pond Pollution Risk Analysis (WTPRA), designed for multiple mine tailings ponds, stemming from previous watershed-scale accidental pollution risk assessments. Transferred and combined risk is embedded using risk rankings of multiple routes of the "source-pathway-target" in the WTPRA. The previous approach is modified using multi-criteria analysis, dam failure models, and instantaneous water quality models, which are modified for application to multiple tailings ponds. The study area covers the basin of Gutanting Reservoir (the largest backup drinking water source for Beijing) in Zhangjiakou City, where many mine tailings ponds are located. The resultant map shows that risk is higher downstream of Gutanting Reservoir and in its two tributary basins (i.e., Qingshui River and Longyang River). Conversely, risk is lower in the midstream and upstream reaches. The analysis also indicates that the most hazardous mine tailings ponds are located in Chongli and Xuanhua, and that Guanting Reservoir is the most vulnerable receptor. Sensitivity and uncertainty analyses are performed to validate the robustness of the WTPRA method.

Accidental Water Pollution Risk Analysis of Mine Tailings Ponds in Guanting Reservoir Watershed, Zhangjiakou City, China

PubMed Central

Liu, Renzhi; Liu, Jing; Zhang, Zhijiao; Borthwick, Alistair; Zhang, Ke

2015-01-01

Over the past half century, a surprising number of major pollution incidents occurred due to tailings dam failures. Most previous studies of such incidents comprised forensic analyses of environmental impacts after a tailings dam failure, with few considering the combined pollution risk before incidents occur at a watershed-scale. We therefore propose Watershed-scale Tailings-pond Pollution Risk Analysis (WTPRA), designed for multiple mine tailings ponds, stemming from previous watershed-scale accidental pollution risk assessments. Transferred and combined risk is embedded using risk rankings of multiple routes of the “source-pathway-target” in the WTPRA. The previous approach is modified using multi-criteria analysis, dam failure models, and instantaneous water quality models, which are modified for application to multiple tailings ponds. The study area covers the basin of Gutanting Reservoir (the largest backup drinking water source for Beijing) in Zhangjiakou City, where many mine tailings ponds are located. The resultant map shows that risk is higher downstream of Gutanting Reservoir and in its two tributary basins (i.e., Qingshui River and Longyang River). Conversely, risk is lower in the midstream and upstream reaches. The analysis also indicates that the most hazardous mine tailings ponds are located in Chongli and Xuanhua, and that Guanting Reservoir is the most vulnerable receptor. Sensitivity and uncertainty analyses are performed to validate the robustness of the WTPRA method. PMID:26633450

Spacecraft Electrical Connector Selection and Application Processes

NASA Technical Reports Server (NTRS)

Iannello, Chris; Davis, Mitchell I; Kichak, Robert A.; Slenski, George

2009-01-01

This assessment was initiated by the NASA Engineering & Safety Center (NESC) after a number of recent "high profile" connector problems, the most visible and publicized of these being the problem with the Space Shuttle's Engine Cut-Off System cryogenic feed-thru connector. The NESC commissioned a review of NASA's connector selection and application processes for space flight applications, including how lessons learned and past problem records are fed back into the processes to avoid recurring issues. Team members were primarily from the various NASA Centers and included connector and electrical parts specialists. The commissioned study was conducted on spacecraft connector selection and application processes at NASA Centers. The team also compared the NASA spacecraft connector selection and application process to the military process, identified recent high profile connector failures, and analyzed problem report data looking for trends and common occurrences. The team characterized NASA's connector problem experience into a list of top connector issues based on anecdotal evidence of a system's impact and commonality between Centers. These top issues are as follows, in no particular rank order: electrically shorted, bent and/or recessed contact pins, contact pin/socket contamination leading to electrically open or intermittencies, connector plating corrosion or corrosion of connector components, low or inadequate contact pin retention forces, contact crimp failures, unmated connectors and mis-wiring due to workmanship errors during installation or maintenance, loose connectors due to manufacturing defects such as wavy washer and worn bayonet retention, damaged connector elastomeric seals and cryogenic connector failure. A survey was also conducted of SAE Connector AE-8C1 committee members regarding their experience relative to the NASA concerns on connectors. The most common responses in order of occurrence were contact retention, plating issues, worn-out or damaged coupling mechanisms, bent pins, contact crimp barrel cracking and torn seals. In addition to these common themes, responses included issues with markings, dimensional errors on the build, contact/socket damage (handling), manufacturing defects and customer misapplication and mishandling. The NESC team concluded that considering the large quantity and wide variety of connectors successfully flown on human and robotic space applications, the number of failures is quite low. However, "high profile" failures with significant cost, schedule, safety, and/or mission success impacts continue to occur. It was also concluded that connector failures occur throughout a system's life-cycle with the majority of connector issues application related. A number of recommendations were identified for improving NASA connector selection processes and overall space connector reliability and performance.

Are Icelandic rock-slope failures paraglacial? Age evaluation of seventeen rock-slope failures in the Skagafjörður area, based on geomorphological stacking, radiocarbon dating and tephrochronology

NASA Astrophysics Data System (ADS)

Mercier, Denis; Coquin, Julien; Feuillet, Thierry; Decaulne, Armelle; Cossart, Etienne; Jónsson, Helgi Pall; Sæmundsson, Þorstein

2017-11-01

In Iceland there are numerous rock-slope failures, especially in the Tertiary basaltic formations of the northern, eastern and northwestern regions. The temporal pattern of rock-slope failures is fundamental for understanding post-glacial events. In the Skagafjörður district, central northern Iceland, 17 rock-slope failures were investigated to determine the age of their occurrence. A geomorphic survey was carried out to identify and characterize landform units, both on the rock-slope failures and in their immediate vicinity. In this coastal area, we used geomorphological stacking which included the relationship between rock-slope failures and raised beaches caused by glacial isostatic rebounds, the chronology of which was established in previous studies. We searched for depressions on the rock-slope failures to then excavate a series of pits and map the stratigraphy. The resulting stratigraphic framework was then validated using (i) radiocarbon dating of wood remains, and (ii) tephrochronology, both of which were complemented by age-depth model calibration. The results confirm that all the rock-slope failures potentially occurred before the Boreal (8 ka), while 94% occurred before the Preboreal (10 ka). They all potentially occurred after the glacial retreat following the maximal ice extent and the Preboreal. More precisely, 11 of them potentially occurred between the Preboreal and the first half of the Holocene. This study demonstrates the relationship between the deglaciation and destabilization of slopes during the paraglacial phase (debuttressing, decompression, glacial isostatic rebound, seismic activity, etc.), which are also controlling factors favouring landsliding, but are difficult to identify for each individual rock-slope failure.

Medical homicide and extreme negligence.

PubMed

Duncanson, Emily; Richards, Virginia; Luce, Kasey M; Gill, James R

2009-03-01

Deaths that occur during medical care for the treatment of a disease are rarely certified as homicides. Some "medical" deaths, however, have been criminally prosecuted for manslaughter, reckless endangerment, or reckless homicide. We describe 5 deaths due to medical complications that underwent criminal prosecution. Three of the deaths were certified as homicides. Deaths certified as homicides due to the actions (or inactions) of a caregiver occur in 3 circumstances. The first is when the medical caregiver intentionally causes the death of the patient. The second is a death due to treatment by an unlicensed fraud or quack. The final circumstance is due to extreme medical negligence that involves a gross and wanton disregard for the well-being of the patient and is the most controversial in the medical community. The law defines reckless endangerment as the conscious disregard of a known substantial likelihood of injury to the patient. Criminal neglect typically is defined as the failure to provide timely, safe, adequate, and appropriate services, treatment, and/or care to a patient. In instances of extreme medical negligence, a homicide manner of death is appropriate because the fatality is due to the criminal acts (or inactions) of another. It also furthers one of the major goals of the medicolegal death investigation system, which is to safeguard the public health.

Rupture testing for the quality control of electrodeposited copper interconnections in high-speed, high-density circuits

NASA Technical Reports Server (NTRS)

Zakraysek, Louis

1987-01-01

Printed Wiring Multilayer Board (PWMLB) structures for high speed, high density circuits are prone to failure due to the microcracking of electrolytic copper interconnections. The failure can occur in the foil that makes up the inner layer traces or in the plated through holes (PTH) deposit that forms the layer to layer interconnections. It is shown that there are some distinctive differences in the quality of Type E copper and that these differences can be detected before its use in a PWMLB. It is suggested that the strength of some Type E copper can be very low when the material is hot and that it is the use of this poor quality material in a PWMLB that results in PTH and inner layer microcracking. Since the PWMLB failure in question are induced by a thermal stress, and since the poorer grades of Type E materials used in these structures are susceptible to premature failure under thermal stress, the use of elevated temperature rupture and creep rupture testing is proposed as a means for screening copper foil, or its PTH equivalent, in order to eliminate the problem of Type E copper microcracking in advanced PWMLBs.

Recent advances in the epidemiology, pathogenesis and prognosis of acute heart failure and cardiomyopathy in Africa.

PubMed

Sliwa, Karen; Mayosi, Bongani M

2013-09-01

This review addresses recent advances in the epidemiology, pathogenesis and prognosis of acute heart failure and cardiomyopathy based on research conducted in Africa. We searched Medline/PubMed for publications on acute decompensated heart failure and cardiomyopathy in Africa for the past 5 years (ie, 1 January 2008 to 31 December 2012). This was supplemented with personal communications with colleagues from Africa working in the field. A large prospective registry has shown that acute decompensated heart failure is caused by hypertension, cardiomyopathy and rheumatic heart disease in 90% of cases, a pattern that is in contrast with the dominance of coronary artery disease in North America and Europe. Furthermore, acute heart failure is a disease of the young with a mean age of 52 years, occurs equally in men and women, and is associated with high mortality at 6 months (∼18%), which is, however, similar to that observed in non-African heart failure registries, suggesting that heart failure has a dire prognosis globally, regardless of aetiology. The molecular genetics of dilated cardiomyopathy, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy in Africans is consistent with observations elsewhere in the world; the unique founder effects in the Afrikaner provide an opportunity for the study of genotype-phenotype correlations in large numbers of individuals with cardiomyopathy due to the same mutation. Advances in the understanding of the molecular mechanisms of peripartum cardiomyopathy have led to promising clinical trials of bromocriptine in the treatment of peripartum heart failure. The key challenges of management of heart failure are the urgent need to increase the use of proven treatments by physicians, and the control of hypertension in primary care and at the population level.

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.

Reliability, Risk and Cost Trade-Offs for Composite Designs

NASA Technical Reports Server (NTRS)

Shiao, Michael C.; Singhal, Surendra N.; Chamis, Christos C.

1996-01-01

Risk and cost trade-offs have been simulated using a probabilistic method. The probabilistic method accounts for all naturally-occurring uncertainties including those in constituent material properties, fabrication variables, structure geometry and loading conditions. The probability density function of first buckling load for a set of uncertain variables is computed. The probabilistic sensitivity factors of uncertain variables to the first buckling load is calculated. The reliability-based cost for a composite fuselage panel is defined and minimized with respect to requisite design parameters. The optimization is achieved by solving a system of nonlinear algebraic equations whose coefficients are functions of probabilistic sensitivity factors. With optimum design parameters such as the mean and coefficient of variation (representing range of scatter) of uncertain variables, the most efficient and economical manufacturing procedure can be selected. In this paper, optimum values of the requisite design parameters for a predetermined cost due to failure occurrence are computationally determined. The results for the fuselage panel analysis show that the higher the cost due to failure occurrence, the smaller the optimum coefficient of variation of fiber modulus (design parameter) in longitudinal direction.

Evaluation of iron aluminide weld overlays for erosion - corrosion resistant boiler tube coatings in low NO{sub x} boilers

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

DuPont, J.N.; Banovic, S.W.; Marder, A.R.

1996-08-01

Low NOx burners are being installed in many fossil fired power plants in order to comply with new Clean Air Regulations. Due to the operating characteristics of these burners, boiler tube sulfidation corrosion is often enhanced and premature tube failures can occur. Failures due to oxidation and solid particle erosion are also a concern. A program was initiated in early 1996 to evaluate the use of iron aluminide weld overlays for erosion/corrosion protection of boiler tubes in Low NOx boilers. Composite iron/aluminum wires will be used with the Gas Metal Arc Welding (GMAW) process to prepare overlays on boiler tubesmore » steels with aluminum contents from 8 to 16wt%. The weldability of the composite wires will be evaluated as a function of chemical composition and welding parameters. The effect of overlay composition on corrosion (oxidation and sulfidation) and solid particle erosion will also be evaluated. The laboratory studies will be complemented by field exposures of both iron aluminide weld overlays and co-extruded tubing under actual boiler conditions.« less

Bleeding with the artificial heart: Gastrointestinal hemorrhage in CF-LVAD patients.

PubMed

Gurvits, Grigoriy E; Fradkov, Elena

2017-06-14

Continuous-flow left ventricular assist devices (CF-LVADs) have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or, more recently, as destination therapy. However, its implantations carries a risk of complications including infection, device malfunction, arrhythmias, right ventricular failure, thromboembolic disease, postoperative and nonsurgical bleeding. A significant number of left ventricular assist devices (LVAD) recipients may experience recurrent gastrointestinal hemorrhage, mainly due to combination of antiplatelet and vitamin K antagonist therapy, activation of fibrinolytic pathway, acquired von Willebrand factor deficiency, and tendency to develop small intestinal angiodysplasias due to increased rotary speed of the pump. Gastrointestinal bleeding in LVAD patients remains a source of increased morbidity including the need for blood transfusions, extended hospital stays, multiple readmissions, and overall mortality. Management of gastrointestinal bleeding in LVAD patients involves multidisciplinary approach in stabilizing the patients, addressing risk factors and performing structured endoluminal evaluation with focus on upper gastrointestinal tract including jejunum to find and eradicate culprit lesion. Medical and procedural intervention is largely successful and universal bleeding cessation occurs in transplanted patients.

Rotor burst protection program: Statistics on aircraft gas turbine engine rotor failures that occurred in US commercial aviation during 1975

NASA Technical Reports Server (NTRS)

Delucia, R. A.; Mangano, G. J.

1977-01-01

Statistics on gas turbine rotor failures that have occurred in U.S. commercial aviation during 1975 are presented. The compiled data were analyzed to establish: (1) The incidence of rotor failures and the number of contained and uncontained rotor bursts; (2) The distribution of rotor bursts with respect to engine rotor component; i.e., fan, compressor or turbine; (3) The type of rotor fragment (disk, rim or blade) typically generated at burst; (4) The cause of failure; (5) The type of engines involved; and (6) The flight condition at the time of failure.

Simulation Assisted Risk Assessment Applied to Launch Vehicle Conceptual Design

NASA Technical Reports Server (NTRS)

Mathias, Donovan L.; Go, Susie; Gee, Ken; Lawrence, Scott

2008-01-01

A simulation-based risk assessment approach is presented and is applied to the analysis of abort during the ascent phase of a space exploration mission. The approach utilizes groupings of launch vehicle failures, referred to as failure bins, which are mapped to corresponding failure environments. Physical models are used to characterize the failure environments in terms of the risk due to blast overpressure, resulting debris field, and the thermal radiation due to a fireball. The resulting risk to the crew is dynamically modeled by combining the likelihood of each failure, the severity of the failure environments as a function of initiator and time of the failure, the robustness of the crew module, and the warning time available due to early detection. The approach is shown to support the launch vehicle design process by characterizing the risk drivers and identifying regions where failure detection would significantly reduce the risk to the crew.

Malfunction and failure of robotic systems during general surgical procedures.

PubMed

Agcaoglu, Orhan; Aliyev, Shamil; Taskin, Halit Eren; Chalikonda, Sricharan; Walsh, Matthew; Costedio, Meagan M; Kroh, Matthew; Rogula, Tomasz; Chand, Bipan; Gorgun, Emre; Siperstein, Allan; Berber, Eren

2012-12-01

There has been recent interest in using robots for general surgical procedures. This shift in technique raises the issue of patient safety with automated instrumentation. Although the safety of robotics has been established for urologic procedures, there are scant data on its use in general surgical procedures. The aim of this study is to analyze the incidence of robotic malfunction and its consequences for general surgical procedures. All robotic general surgical procedures performed at a tertiary center between 2008 and 2011 were reviewed from institutional review board (IRB)-approved prospective databases. A total of 223 cases were done robotically, including 102 endocrine, 83 hepatopancreaticobiliary, 17 upper gastrointestinal, and 21 lower gastrointestinal colorectal procedures. There were 10 cases of robotic malfunction (4.5%). These failures were related to robotic instruments (n = 4), optical system (n = 3), robotic arms (n = 2), and robotic console (n = 1). None of these failures led to adverse patient consequences or conversion to open. Six (2.7%) cases were converted to open due to bleeding (n = 3), difficult dissection plane (n = 1), invasion of tumor to surrounding structures (n = 1), and intolerance of pneumoperitoneum due to CO(2) retention (n = 1). There was no mortality, and morbidity was 1% (n = 2). To our knowledge, this is the largest North American report to date on robotic general surgical procedures. Our results show that robotic malfunction occurs in a minority of cases, with no adverse consequences. We believe that awareness of these failures and knowing how to troubleshoot are important to maintain the efficiency of these procedures.

Acoustic emission and acousto-ultrasonic signature analysis of failure mechanisms in carbon fiber reinforced polymer materials

NASA Astrophysics Data System (ADS)

Carey, Shawn Allen

Fiber reinforced polymer composite materials, particularly carbon (CFRPs), are being used for primary structural applications, particularly in the aerospace and naval industries. Advantages of CFRP materials, compared to traditional materials such as steel and aluminum, include: light weight, high strength to weight ratio, corrosion resistance, and long life expectancy. A concern with CFRPs is that despite quality control during fabrication, the material can contain many hidden internal flaws. These flaws in combination with unseen damage due to fatigue and low velocity impact have led to catastrophic failure of structures and components. Therefore a large amount of research has been conducted regarding nondestructive testing (NDT) and structural health monitoring (SHM) of CFRP materials. The principal objective of this research program was to develop methods to characterize failure mechanisms in CFRP materials used by the U.S. Army using acoustic emission (AE) and/or acousto-ultrasonic (AU) data. Failure mechanisms addressed include fiber breakage, matrix cracking, and delamination due to shear between layers. CFRP specimens were fabricated and tested in uniaxial tension to obtain AE and AU data. The specimens were designed with carbon fibers in different orientations to produce the different failure mechanisms. Some specimens were impacted with a blunt indenter prior to testing to simulate low-velocity impact. A signature analysis program was developed to characterize the AE data based on data examination using visual pattern recognition techniques. It was determined that it was important to characterize the AE event , using the location of the event as a parameter, rather than just the AE hit (signal recorded by an AE sensor). A back propagation neural network was also trained based on the results of the signature analysis program. Damage observed on the specimens visually with the aid of a scanning electron microscope agreed with the damage type assigned by the signature analysis program. The load level at which significant damage occurred in the specimens was evaluated using ASME Boiler and Pressure Vessel criteria. AU testing proved inconclusive for characterization of the damage due to common problems associated with AU testing such as: reproducibility difficulties due to degradation of the attachment of the sensors, damage not detected unless in the line of sight between sensors, and large intrinsic variation of the data.

Deficiencies in the uterine environment and failure to support embryo development

USDA-ARS?s Scientific Manuscript database

Pregnancy failure in livestock can result from failure to fertilize the oocyte or embryonic loss during gestation. Although fertilization failure occurs, embryonic mortality has a greater contribution to pregnancy failure. The focus of this review is on cattle and factors affecting, and mechanisms r...

Fault detection and identification in missile system guidance and control: a filtering approach

NASA Astrophysics Data System (ADS)

Padgett, Mary Lou; Evers, Johnny; Karplus, Walter J.

1996-03-01

Real-world applications of computational intelligence can enhance the fault detection and identification capabilities of a missile guidance and control system. A simulation of a bank-to- turn missile demonstrates that actuator failure may cause the missile to roll and miss the target. Failure of one fin actuator can be detected using a filter and depicting the filter output as fuzzy numbers. The properties and limitations of artificial neural networks fed by these fuzzy numbers are explored. A suite of networks is constructed to (1) detect a fault and (2) determine which fin (if any) failed. Both the zero order moment term and the fin rate term show changes during actuator failure. Simulations address the following questions: (1) How bad does the actuator failure have to be for detection to occur, (2) How bad does the actuator failure have to be for fault detection and isolation to occur, (3) are both zero order moment and fine rate terms needed. A suite of target trajectories are simulated, and properties and limitations of the approach reported. In some cases, detection of the failed actuator occurs within 0.1 second, and isolation of the failure occurs 0.1 after that. Suggestions for further research are offered.

Novel insights into the development of chagasic cardiomyopathy: role of PI3Kinase/NO axis.

PubMed

Roman-Campos, Danilo; Sales-Junior, Policarpo; Duarte, Hugo L; Gomes, Enéas R; Lara, Aline; Campos, Paula; Rocha, Nazareth N; Resende, Rodrigo R; Ferreira, Anderson; Guatimosim, Sílvia; Gazzinelli, Ricardo T; Ropert, Catherine; Cruz, Jader S

2013-09-10

Chagas' disease is one of the leading causes of heart failure in Latin American countries. Despite its great social impact, there is no direct evidence in the literature explaining the development of heart failure in Chagas' disease. Therefore, the main objective of the study was to investigate the development of the Chagas' disease towards its chronic phase and correlate with modifications in the cellular electrophysiological characteristics of the infected heart. Using a murine model of Chagas' disease, we confirmed and extended previous findings of altered electrocardiogram and echocardiogram in this cardiomyopathy. The observed changes in the electrocardiogram were correlated with the prolonged action potential and reduced transient outward potassium current density. Reduced heart function was associated with remodeling of intracellular calcium handling, altered extracellular matrix content, and to a set of proteins involved in the control of cellular contractility in ventricular myocytes. Furthermore, disruption of calcium homeostasis was partially due to activation of the PI3Kinase/nitric oxide signaling pathway. Finally, we propose a causal link between the inflammatory mediators and heart remodeling during chagasic cardiomyopathy. Altogether our results demonstrate that heart failure in Chagas' disease may occur due to electrical and mechanical remodeling of cardiac myocytes, and suggest that AKT/PI3K/NO axis could be an important pharmacological target to improve the disease outcome. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Results of extracorporeal life support implementation in routine clinical practice: single center experience

PubMed Central

Biočina, Bojan; Petričević, Mate; Belina, Dražen; Gašparović, Hrvoje; Svetina, Lucija; Konosić, Sanja; White, Alexandra; Ivančan, Višnja; Kopjar, Tomislav; Miličić, Davor

2014-01-01

Aim To describe our experience in the clinical application of extracorporeal life support (ECLS) and analyze whether ECLS leads to acceptable clinical outcomes in patients with cardiac failure. Methods Data from clinical database of University Hospital Center Zagreb, Croatia, on 75 patients undergoing ECLS support from 2009 to 2014 due to cardiac failure were retrospectively analyzed. Outcomes were defined as procedural and clinical outcomes. ECLS as a primary procedure and ECLS as a postcardiotomy procedure due to inability to wean from cardiopulmonary bypass were analyzed. Results ECLS was used in 75 adult patients, and in 24 (32%) of those procedural success was noted. ECLS was implemented as a primary procedure in 36 patients and as a postcardiotomy procedure in 39 patients. Nine out of 39 (23.08%) patients had postcardiotomy ECLS after heart transplantation. Bleeding complications occurred in 30 (40%) patients, both in primary (11/36 patients) and postcardiotomy group (19/39 patients). ECLS was established by peripheral approach in 46 patients and by central cannulation in 27 patients. In 2 patients, combined cannulation was performed, with an inflow cannula placed into the right atrium and an outflow cannula placed into the femoral artery. Eleven patients treated with peripheral approach had ischemic complications. Conclusion ECLS is a useful tool in the treatment of patients with refractory cardiac failure and its results are encouraging in patients who otherwise have an unfavorable prognosis. PMID:25559831

Thyroid hormone levels in the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex.

PubMed Central

Tang, W W; Kaptein, E M

1989-01-01

Hypothalamic-pituitary dysfunction and thyroid gland cytomegalovirus inclusions have been described in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC). We evaluated 80 patients with AIDS or ARC for the frequency of hypothalamic-pituitary or thyroid gland failure and altered serum thyroid hormone levels due to nonthyroidal disorders. One patient had subclinical hypothyroidism. Of these patients, 60% had low free triiodothyronine (T3) index values and 4% had low free thyroxine (T4) indexes; none of the latter had hypothalamic-pituitary or thyroid gland failure, since all serum cortisol values were greater than or equal to 552 nmol per liter (greater than or equal to 20 micrograms per dl) and all thyrotropin levels were less than or equal to 3 mU per liter (less than or equal to 3 microU per ml), respectively. Those who died had lower total T4 and T3, free T3 index, and albumin levels than those discharged from hospital. Serum total T4 and T3 levels correlated with albumin levels and total T3 with serum sodium levels. Serum total T3 levels best predicted the outcome of the hospital stay (accuracy = 82%). Thus, abnormal serum thyroid hormone levels in AIDS or ARC patients are most frequently due to nonthyroidal disorders, but hypothalamic-pituitary or thyroid gland failure may occur. PMID:2618039

Sudden onset odontoid fracture caused by cervical instability in hypotonic cerebral palsy.

PubMed

Shiohama, Tadashi; Fujii, Katsunori; Kitazawa, Katsuhiko; Takahashi, Akiko; Maemoto, Tatsuo; Honda, Akihito

2013-11-01

Fractures of the upper cervical spine rarely occur but carry a high rate of mortality and neurological disabilities in children. Although odontoid fractures are commonly caused by high-impact injuries, cerebral palsy children with cervical instability have a risk of developing spinal fractures even from mild trauma. We herein present the first case of an odontoid fracture in a 4-year-old boy with cerebral palsy. He exhibited prominent cervical instability due to hypotonic cerebral palsy from infancy. He suddenly developed acute respiratory failure, which subsequently required mechanical ventilation. Neuroimaging clearly revealed a type-III odontoid fracture accompanied by anterior displacement with compression of the cervical spinal cord. Bone mineral density was prominently decreased probably due to his long-term bedridden status and poor nutritional condition. We subsequently performed posterior internal fixation surgically using an onlay bone graft, resulting in a dramatic improvement in his respiratory failure. To our knowledge, this is the first report of an odontoid fracture caused by cervical instability in hypotonic cerebral palsy. Since cervical instability and decreased bone mineral density are frequently associated with cerebral palsy, odontoid fractures should be cautiously examined in cases of sudden onset respiratory failure and aggravated weakness, especially in hypotonic cerebral palsy patients. Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Intermediate Temperature Stress Rupture of a Woven Hi-Nicalon, BN-Interphase, SiC Matric Composite in Air

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Hurst, Janet; Brewer, David

1999-01-01

Woven Hi-Nicalon (TM) reinforced melt-infiltrated SiC matrix composites were tested under tensile stress-rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage during the experiment. Extensive microscopy of the composite fracture surfaces and the individual fiber fracture surfaces was used to determine the mechanisms leading to ultimate failure. The rupture properties of these composites were significantly worse than expected compared to the fiber properties under similar conditions. This was due to the oxidation of the BN interphase. Oxidation occurred through the matrix cracks that intersected the surface or edge of a tensile bar. These oxidation reactions resulted in minor degradation to fiber strength and strong bonding of the fibers to one another at regions of near fiber-to-fiber contact. It was found that two regimes for rupture exist for this material: a high stress regime where rupture occurs at a fast rate and a low stress regime where rupture occurs at a slower rate. For the high stress regime, the matrix damage state consisted of through thickness cracks. The average fracture strength of fibers that were pulled-out (the final fibers to break before ultimate failure) was controlled by the slow-crack growth rupture criterion in the literature for individual Hi-Nicalon (TM) fibers. For the low stress regime, the matrix damage state consisted of microcracks which grew during the rupture test. The average fracture strength of fibers that were pulled-out in this regime was the same as the average fracture strength of individual fibers pulled out in as-produced composites tested at room temperature.

Influence of biofilm lubricity on shear-induced transmission of staphylococcal biofilms from stainless steel to silicone rubber.

PubMed

Gusnaniar, Niar; Sjollema, Jelmer; Jong, Ed D; Woudstra, Willem; de Vries, Joop; Nuryastuti, Titik; van der Mei, Henny C; Busscher, Henk J

2017-11-01

In real-life situations, bacteria are often transmitted from biofilms growing on donor surfaces to receiver ones. Bacterial transmission is more complex than adhesion, involving bacterial detachment from donor and subsequent adhesion to receiver surfaces. Here, we describe a new device to study shear-induced bacterial transmission from a (stainless steel) pipe to a (silicone rubber) tube and compare transmission of EPS-producing and non-EPS-producing staphylococci. Transmission of an entire biofilm from the donor to the receiver tube did not occur, indicative of cohesive failure in the biofilm rather than of adhesive failure at the donor-biofilm interface. Biofilm was gradually transmitted over an increasing length of receiver tube, occurring mostly to the first 50 cm of the receiver tube. Under high-shearing velocity, transmission of non-EPS-producing bacteria to the second half decreased non-linearly, likely due to rapid thinning of the lowly lubricious biofilm. Oppositely, transmission of EPS-producing strains to the second tube half was not affected by higher shearing velocity due to the high lubricity and stress relaxation of the EPS-rich biofilms, ensuring continued contact with the receiver. The non-linear decrease of ongoing bacterial transmission under high-shearing velocity is new and of relevance in for instance, high-speed food slicers and food packaging. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Severe tricuspid regurgitation and isolated right heart failure due to thyrotoxicosis

PubMed Central

Bonou, Maria; Lampropoulos, Konstantinos M.; Andriopoulou, Maria; Kotsas, Dimitrios; Lakoumentas, John; Barbetseas, John

2012-01-01

We describe the case of a patient presented with isolated right heart failure with atrial fibrillation and severe tricuspid regurgitation due to hyperthyroidism. Treatment of the thyroid disease resulted in the disappearance of signs of right heart failure and resolution of the valve incompetence and normalization of the heart rhythm. Although thyrotoxicosis may be associated with congestive heart failure, isolated right heart failure with marked tricuspid regurgitation is rarely seen. PMID:23253416

Methicillin-Resistant Staphylococcus aureus in Foot Osteomyelitis.

PubMed

Ashong, Chester N; Raheem, Shazia A; Hunter, Andrew S; Mindru, Cezarina; Barshes, Neal R

Conflicting studies exist regarding the impact of methicillin-resistant Staphylococcus aureus (MRSA) on increased time to wound healing, future need for surgical procedures, and likelihood of treatment failure in patients with diabetic foot osteomyelitis. The purpose of this study is to determine the overall significance of MRSA in predicting treatment failure in bone infections of the foot and to determine an appropriate pre-operative and empiric post-operative antibiotic regimen. Patients presenting with an initial episode of "probable" or "definite" foot osteomyelitis were included for review and analysis if the following criteria were met: (1) Osteomyelitis occurred in the foot (i.e., distal to the malleoli of the ankle); episodes occurring above the ankle were excluded. (2) Patients received either no antibiotics or only oral antibiotics for long-term treatment; episodes managed with long-term parenteral antibiotics were excluded. (3) The infection was managed initially with medical therapy or conservative surgical therapy; episodes managed with major (above-ankle) amputation as the initial treatment were excluded. The primary objective of this study was to assess whether episodes of foot osteomyelitis associated with MRSA resulted in treatment failure more frequently than not. Of 178 episodes included in the study, 50 (28.1%) episodes had treatment failure. Median time-to-treatment failure was 60 days (range 7-598 days). In 28.1% (9/32 episodes) in which treatment failure occurred and 39.0% (41/105) episodes in which no treatment failure occurred, MRSA was present. The presence of MRSA was not significantly associated with treatment failure (p = 0.99). The presence of MRSA in bone culture and whether antibiotic use had anti-MRSA activity was not associated with increased treatment failure of diabetic foot osteomyelitis in our institution. Empiric antibiotic coverage of MRSA may not be necessary for many patients presenting with foot osteomyelitis.

Biological and technical complications and failures with fixed partial dentures (FPD) on implants and teeth after four to five years of function.

PubMed

Brägger, U; Aeschlimann, S; Bürgin, W; Hämmerle, C H; Lang, N P

2001-02-01

The aim of this study was to compare the frequency of biological and technical complications with fixed partial dentures (FPDs) on implants, teeth and as mixed tooth-implant supported FPDs over 4 to 5 years of function. All implants belonged to the ITI Dental Implant System. Group I-I (implant FPD) included 33 patients with 40 FPDs, group T-T (tooth FPDs) 40 patients with 58 FPDs, group I-T (mixed tooth-implant FPDs) 15 with 18 FPD. Of the bridge abutments 144 were teeth and 105 were implants. The median number of units replaced by the FPDs was 3 (range 2-14). The mean age of the patients was 55.7 years (range 23-83). Complete failures resulted in the loss of one FPD in each group. Two implants were lost due to fracture secondarily to development of a bone defect. One tooth had a vertical fracture and 1 tooth was lost due to periodontitis. Biological complications (peri-implantitis, PPD > or = 5 mm and BOP+) occurred at 9.6% (10) of the implants. This number was, however, reduced to 5% if the threshold for definition of peri-implantitis was set at PPD > or = 6 mm and BOP+. Biological complications occurred in 11.8% (17) of the abutment teeth (NS compared to implants); 2.8% (4) had secondary caries, 4.9% (7) endodontic problems and 4.1% (6) had periodontitis (PPD > or = 5 mm, BOP+). Ten out of 32 patients with a general health problem indicated a biological complication, whereas 9 out of 53 patients with no general health problem had a biological complication (chi 2: NS). Statistically significantly more technical complications were found in FPDs on implants (chi 2, P < or = 0.05). The technical complications were associated with bruxism. Out of 10 bruxers 6 had a technical complication whereas 13 out of 75 non-bruxers had such a complication (chi 2 < or = 0.01). Extensions were associated with more technical complications (13 out of 35 with extensions versus 9 out of 81 without). In conclusion, favourable clinical conditions were found at tooth and implant abutments after 4-5 years of function. Loss of FPD over 4-5 years occurred at a similar rate with mixed, implant or tooth supported reconstructions. Significantly more porcelain fractures were found in FPDs on implants. Impaired general health status was not significantly associated with more biological failures but bruxism as well as extensions were associated with more technical failures.

Blueberry muffin rash, hyperbilirubinemia, and hypoglycemia: a case of hemolytic disease of the fetus and newborn due to anti-Kp(a).

PubMed

Brumbaugh, J E; Morgan, S; Beck, J C; Zantek, N; Kearney, S; Bendel, C M; Roberts, K D

2011-05-01

Hemolytic disease of the fetus and newborn occurs when maternal IgG antibodies cross the placenta and cause hemolysis of fetal red blood cells. Kp(a) is a low frequency red blood cell antigen that has rarely been implicated in hemolytic disease of the fetus and newborn. The few reported cases attributed to anti-Kp(a) have typically had minimal clinical consequences. We report a critically ill neonate who presented with purpura, respiratory failure, severe liver dysfunction, hyperbilirubinemia, hypoglycemia and anemia. This case report broadens the spectrum of neonatal disease associated with anti-Kp(a), addresses the evaluation of hemolysis with liver failure in a neonate, and emphasizes the importance of screening for antibodies to low frequency red blood cell antigens in suspected hemolytic disease of the fetus and newborn.

Pre-conditioning procedure suitable for internal-RF-antenna of J-PARC RF-driven H{sup −} ion source

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

Ueno, A., E-mail: akira.ueno@j-parc.jp; Ohkoshi, K.; Ikegami, K.

The Japan Proton Accelerator Research Complex (J-PARC) cesiated RF-driven H{sup −} ion source has been successfully operated for about 1 yr. By the world brightest level beam, the J-PARC design beam power of 1 MW was successfully demonstrated. Although no internal-RF-antenna failure, except for the once caused by an excess cesium due to a misoperation, occurred in the operation, many antennas failed in pre-conditionings for the first hundred days. The antenna failure rate was drastically decreased by using an antenna with coating thicker than a standard value and the pre-conditioning procedure repeating 15 min 25 kW RF-power operation and impurity-gasmore » evacuation a few times, before the full power (50 kW) operation.« less

Brain susceptibility to oxidative stress in the perinatal period.

PubMed

Perrone, Serafina; Tataranno, Luisa M; Stazzoni, Gemma; Ramenghi, Luca; Buonocore, Giuseppe

2015-11-01

Oxidative stress (OS) occurs at birth in all newborns as a consequence of the hyperoxic challenge due to the transition from the hypoxic intrauterine environment to extrauterine life. Free radical (FRs) sources such as inflammation, hyperoxia, hypoxia, ischaemia-reperfusion, neutrophil and macrophage activation, glutamate and free iron release, all increases the OS during the perinatal period. Newborns, and particularly preterm infants, have reduced antioxidant defences and are not able to counteract the harmful effects of FRs. Energy metabolism is central to life because cells cannot exist without an adequate supply of ATP. Due to its growth, the mammalian brain can be considered as a steady-state system in which ATP production matches ATP utilisation. The developing brain is particularly sensitive to any disturbances in energy generation, and even a short-term interruption can lead to long-lasting and irreversible damage. Whenever energy failure develops, brain damage can occur. Accumulating evidence indicates that OS is implicated in the pathogenesis of many neurological diseases, such as intraventricular haemorrhage, hypoxic-ischaemic encephalopathy and epilepsy.

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section.

PubMed

Bulusu, Kartik V; Plesniak, Michael W

2016-07-19

The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and tortuosity). Secondary flow structures are vortical flow patterns that occur in curved arteries due to the combined action of centrifugal forces, adverse pressure gradients and inflow characteristics. Such flow morphologies are greatly affected by pulsatility and multiple harmonics of physiological inflow conditions and vary greatly in size-strength-shape characteristics compared to non-physiological (steady and oscillatory) flows (1 - 7). Secondary flow structures may ultimately influence the wall shear stress and exposure time of blood-borne particles toward progression of atherosclerosis, restenosis, sensitization of platelets and thrombosis (4 - 6, 8 - 13). Therefore, the ability to detect and characterize these structures under laboratory-controlled conditions is precursor to further clinical investigations. A common surgical treatment to atherosclerosis is stent implantation, to open up stenosed arteries for unobstructed blood flow. But the concomitant flow perturbations due to stent installations result in multi-scale secondary flow morphologies (4 - 6). Progressively higher order complexities such as asymmetry and loss in coherence can be induced by ensuing stent failures vis-à-vis those under unperturbed flows (5). These stent failures have been classified as "Types I-to-IV" based on failure considerations and clinical severity (14). This study presents a protocol for the experimental investigation of the complex secondary flow structures due to complete transverse stent fracture and linear displacement of fractured parts ("Type IV") in a curved artery model. The experimental method involves the implementation of particle image velocimetry (2C-2D PIV) techniques with an archetypal carotid artery inflow waveform, a refractive index matched blood-analog working fluid for phase-averaged measurements (15 - 18). Quantitative identification of secondary flow structures was achieved using concepts of flow physics, critical point theory and a novel wavelet transform algorithm applied to experimental PIV data (5, 6, 19 - 26).

Influence of follicular characteristics at ovulation on early embryo survival

USDA-ARS?s Scientific Manuscript database

Reproductive failure in livestock can result from failure to fertilize the oocyte or embryonic loss during gestation. Although fertilization failure occurs, embryonic mortality represents a greater contribution to reproductive failure. Reproductive success varies between species and production goal...

Humboldt slide - A large shear-dominated retrogressive slope failure

USGS Publications Warehouse

Gardner, J.V.; Prior, D.B.; Field, M.E.

1999-01-01

Humboldt Slide is a large, complex slide zone located on the northern California continental margin. Its three-dimensional architecture has been imaged by a combination of multibeam bathymetry, Huntec Deep-Tow seismic profiling, and sidescan sonar. The slide is interpreted to be Late Pleistocene to early Holocene in age and was caused by a combination of factors. The area of the slide is a local depocenter with high accumulation rates of organic-rich sediment; there has been local steepening of slopes by tectonic uplifts; and the entire area is one of high seismicity. Overall, the failure occurred by retrogressive, shear-dominated, minimum movement apparently as a sequence of events. Failure initially occurred by subsidence extension at the middle of the feature, followed by upslope retrogressive failure and downslope compression, and finally by translational sliding at the top of the slide. Degassing, as evidenced by abundant pockmarks, may have inhibited downslope translation. The slide may still be active, as suggested by offsets in Holocene hemipelagic sediment draped over some of the shear surfaces. Crown cracks occur above the present head of the failure and may represent the next generation of failure.

Reward system and temporal pole contributions to affective evaluation during a first person shooter video game.

PubMed

Mathiak, Krystyna A; Klasen, Martin; Weber, René; Ackermann, Hermann; Shergill, Sukhwinder S; Mathiak, Klaus

2011-07-12

Violent content in video games evokes many concerns but there is little research concerning its rewarding aspects. It was demonstrated that playing a video game leads to striatal dopamine release. It is unclear, however, which aspects of the game cause this reward system activation and if violent content contributes to it. We combined functional Magnetic Resonance Imaging (fMRI) with individual affect measures to address the neuronal correlates of violence in a video game. Thirteen male German volunteers played a first-person shooter game (Tactical Ops: Assault on Terror) during fMRI measurement. We defined success as eliminating opponents, and failure as being eliminated themselves. Affect was measured directly before and after game play using the Positive and Negative Affect Schedule (PANAS). Failure and success events evoked increased activity in visual cortex but only failure decreased activity in orbitofrontal cortex and caudate nucleus. A negative correlation between negative affect and responses to failure was evident in the right temporal pole (rTP). The deactivation of the caudate nucleus during failure is in accordance with its role in reward-prediction error: it occurred whenever subject missed an expected reward (being eliminated rather than eliminating the opponent). We found no indication that violence events were directly rewarding for the players. We addressed subjective evaluations of affect change due to gameplay to study the reward system. Subjects reporting greater negative affect after playing the game had less rTP activity associated with failure. The rTP may therefore be involved in evaluating the failure events in a social context, to regulate the players' mood.

Initial use of echinocandins does not negatively influence outcome in Candida parapsilosis bloodstream infection: a propensity score analysis.

PubMed

Fernández-Ruiz, Mario; Aguado, José María; Almirante, Benito; Lora-Pablos, David; Padilla, Belén; Puig-Asensio, Mireia; Montejo, Miguel; García-Rodríguez, Julio; Pemán, Javier; Ruiz Pérez de Pipaón, Maite; Cuenca-Estrella, Manuel

2014-05-01

Concerns have arisen regarding the optimal antifungal regimen for Candida parapsilosis bloodstream infection (BSI) in view of its reduced susceptibility to echinocandins. The Prospective Population Study on Candidemia in Spain (CANDIPOP) is a prospective multicenter, population-based surveillance program on Candida BSI conducted through a 12-month period in 29 Spanish hospitals. Clinical isolates were identified by DNA sequencing, and antifungal susceptibility testing was performed by the European Committee on Antimicrobial Susceptibility Testing methodology. Predictors for clinical failure (all-cause mortality between days 3 to 30, or persistent candidemia for ≥72 hours after initiation of therapy) in episodes of C. parapsilosis species complex BSI were assessed by logistic regression analysis. We further analyzed the impact of echinocandin-based regimen as the initial antifungal therapy (within the first 72 hours) by using a propensity score approach. Among 752 episodes of Candida BSI identified, 200 (26.6%) were due to C. parapsilosis species complex. We finally analyzed 194 episodes occurring in 190 patients. Clinical failure occurred in 58 of 177 (32.8%) of evaluable episodes. Orotracheal intubation (adjusted odds ratio [AOR], 2.81; P = .018) and septic shock (AOR, 2.91; P = .081) emerged as risk factors for clinical failure, whereas early central venous catheter removal was protective (AOR, 0.43; P = .040). Neither univariate nor multivariate analysis revealed that the initial use of an echinocandin-based regimen had any impact on the risk of clinical failure. Incorporation of the propensity score into the model did not change this finding. The initial use of an echinocandin-based regimen does not seem to negatively influence outcome in C. parapsilosis BSI.

The pacemaker-twiddler's syndrome: an infrequent cause of pacemaker failure.

PubMed

Salahuddin, Mohammad; Cader, Fathima Aaysha; Nasrin, Sahela; Chowdhury, Mashhud Zia

2016-01-20

The pacemaker-twiddler's syndrome is an uncommon cause of pacemaker malfunction. It occurs due to unintentional or deliberate manipulation of the pacemaker pulse generator within its skin pocket by the patient. This causes coiling of the lead and its dislodgement, resulting in failure of ventricular pacing. More commonly reported among elderly females with impaired cognition, the phenomenon usually occurs in the first year following pacemaker implantation. Treatment involves repositioning of the dislodged leads and suture fixation of the lead and pulse generator within its pocket. An 87 year old Bangladeshi lady who underwent a single chamber ventricular pacemaker (VVI mode: i.e. ventricle paced, ventricle sensed, inhibitory mode) implantation with the indication of complete heart block, and presented to us again 7 weeks later, with syncopal attacks. She admitted to repeatedly manipulating the pacemaker generator in her left pectoral region. Physical examination revealed a heart rate of 42 beats/minute, blood pressure 140/80 mmHg and bilateral crackles on lung auscultation. She had no cognitive deficit. An immediate electrocardiogram showed complete heart block with pacemaker spikes and failure to capture. Chest X-ray showed coiled and retracted right ventricular lead and rotated pulse generator. An emergent temporary pace maker was set at a rate of 60 beats per minute. Subsequently, she underwent successful lead repositioning with strong counselling to avoid further twiddling. Twiddler's syndrome should be considered as a cause of pacemaker failure in elderly patients presenting with bradyarrythmias following pacemaker implantation. Chest X-ray and electrocardiograms are simple and easily-available first line investigations for its diagnosis. Lead repositioning is required, however proper patient education and counselling against further manipulation is paramount to long-term management.

Four faces of baroreflex failure: hypertensive crisis, volatile hypertension, orthostatic tachycardia, and malignant vagotonia

NASA Technical Reports Server (NTRS)

Ketch, Terry; Biaggioni, Italo; Robertson, RoseMarie; Robertson, David

2002-01-01

BACKGROUND: The baroreflex normally serves to buffer blood pressure against excessive rise or fall. Baroreflex failure occurs when afferent baroreceptive nerves or their central connections become impaired. In baroreflex failure, there is loss of buffering ability, and wide excursions of pressure and heart rate occur. Such excursions may derive from endogenous factors such as stress or drowsiness, which result in quite high and quite low pressures, respectively. They may also derive from exogenous factors such as drugs or environmental influences. METHODS AND RESULTS: Impairment of the baroreflex may produce an unusually broad spectrum of clinical presentations; with acute baroreflex failure, a hypertensive crisis is the most common presentation. Over succeeding days to weeks, or in the absence of an acute event, volatile hypertension with periods of hypotension occurs and may continue for many years, usually with some attenuation of pressor surges and greater prominence of depressor valleys during long-term follow-up. With incomplete loss of baroreflex afferents, a mild syndrome of orthostatic tachycardia or orthostatic intolerance may appear. Finally, if the baroreflex failure occurs without concomitant destruction of the parasympathetic efferent vagal fibers, a resting state may lead to malignant vagotonia with severe bradycardia and hypotension and episodes of sinus arrest. CONCLUSIONS: Although baroreflex failure is not the most common cause of the above conditions, correct differentiation from other cardiovascular disorders is important, because therapy of baroreflex failure requires specific strategies, which may lead to successful control.

A Numerical Solution Routine for Investigating Oxidation-Induced Strength Degradation Mechanisms in SiC/SiC Composites

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2015-01-01

The stress rupture strength of silicon carbide fiber-reinforced silicon carbide (SiCSiC) composites with a boron nitride (BN) fiber coating decreases with time within the intermediate temperature range of 700-950 C. Various theories have been proposed to explain the cause of the time dependent stress rupture strength. Some previous authors have suggested that the observed composite strength behavior is due to the inherent time dependent strength of the fibers, which is caused by the slow growth of flaws within the fibers. Flaw growth is supposedly enabled by oxidation of free carbon at the grain boundaries. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of SiCSiC composites. This is achieved through the development of a numerically-based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time dependent behavior.

A Brownian model for recurrent earthquakes

USGS Publications Warehouse

Matthews, M.V.; Ellsworth, W.L.; Reasenberg, P.A.

2002-01-01

We construct a probability model for rupture times on a recurrent earthquake source. Adding Brownian perturbations to steady tectonic loading produces a stochastic load-state process. Rupture is assumed to occur when this process reaches a critical-failure threshold. An earthquake relaxes the load state to a characteristic ground level and begins a new failure cycle. The load-state process is a Brownian relaxation oscillator. Intervals between events have a Brownian passage-time distribution that may serve as a temporal model for time-dependent, long-term seismic forecasting. This distribution has the following noteworthy properties: (1) the probability of immediate rerupture is zero; (2) the hazard rate increases steadily from zero at t = 0 to a finite maximum near the mean recurrence time and then decreases asymptotically to a quasi-stationary level, in which the conditional probability of an event becomes time independent; and (3) the quasi-stationary failure rate is greater than, equal to, or less than the mean failure rate because the coefficient of variation is less than, equal to, or greater than 1/???2 ??? 0.707. In addition, the model provides expressions for the hazard rate and probability of rupture on faults for which only a bound can be placed on the time of the last rupture. The Brownian relaxation oscillator provides a connection between observable event times and a formal state variable that reflects the macromechanics of stress and strain accumulation. Analysis of this process reveals that the quasi-stationary distance to failure has a gamma distribution, and residual life has a related exponential distribution. It also enables calculation of "interaction" effects due to external perturbations to the state, such as stress-transfer effects from earthquakes outside the target source. The influence of interaction effects on recurrence times is transient and strongly dependent on when in the loading cycle step pertubations occur. Transient effects may be much stronger than would be predicted by the "clock change" method and characteristically decay inversely with elapsed time after the perturbation.

Comparison of fracture strength and failure mode of different ceramic implant abutments.

PubMed

Elsayed, Adham; Wille, Sebastian; Al-Akhali, Majed; Kern, Matthias

2017-04-01

The whitish color of zirconia (ZrO 2 ) abutments offers favorable esthetics compared with the grayish color of titanium (Ti) abutments. Nonetheless, ZrO 2 has greater opacity, making it difficult to achieve natural tooth color. Therefore, lithium disilicate (LaT) abutments have been suggested to replace metal abutments. The purpose of this in vitro study was to evaluate the fracture strength and failure mode of single-tooth implant restorations using ZrO 2 and LaT abutments, and to compare them with titanium (Ti) abutments. Five different types of abutments, Ti; ZrO 2 with no metal base; ZrO 2 with a metal base (ZrT); LaT; and LaT combination abutment and crown (LcT) were assembled on 40 Ti implants and restored with LaT crowns. Specimens were subjected to quasistatic loading using a universal testing machine, until the implant-abutment connection failed. As bending of the metal would be considered a clinical failure, the values of force (N) at which the plastic deformation of the metal occurred were calculated, and the rate of deformation was analyzed. Statistical analysis was done using the Mann-Whitney U test (α=.05). Group ZrO 2 revealed the lowest resistance to failure with a mean of 202 ±33 N. Groups ZrT, LaT, and LaC withstood higher forces without fracture or debonding of the ceramic suprastructure, and failure was due to deformation of metal bases, with no statistically significant differences between these groups regarding the bending behavior. Within the limitations of this in vitro study, it was concluded that LaT abutments have the potential to withstand the physiological occlusal forces that occur in the anterior region and that ZrO 2 abutments combined with Ti inserts have much higher fracture strength than pure ZrO 2 abutments. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Phrenic nerve stimulation for the treatment of central sleep apnea.

PubMed

Abraham, William T; Jagielski, Dariusz; Oldenburg, Olaf; Augostini, Ralph; Krueger, Steven; Kolodziej, Adam; Gutleben, Klaus-Jürgen; Khayat, Rami; Merliss, Andrew; Harsch, Manya R; Holcomb, Richard G; Javaheri, Shahrokh; Ponikowski, Piotr

2015-05-01

The aim of this study was to evaluate chronic, transvenous, unilateral phrenic nerve stimulation to treat central sleep apnea (CSA) in a prospective, multicenter, nonrandomized study. CSA occurs predominantly in patients with heart failure and increases the risk for morbidity and mortality. Established therapies for CSA are lacking, and those available are limited by poor patient adherence. Fifty-seven patients with CSA underwent baseline polysomnography followed by transvenous phrenic nerve stimulation system implantation and follow-up. Feasibility was assessed by implantation success rate and therapy delivery. Safety was evaluated by monitoring of device- and procedure-related adverse events. Efficacy was evaluated by changes in the apnea-hypopnea index at 3 months. Quality of life at 6 months was evaluated using a sleepiness questionnaire, patient global assessment, and, in patients with heart failure at baseline, the Minnesota Living With Heart Failure Questionnaire. The study met its primary end point, demonstrating a 55% reduction in apnea-hypopnea index from baseline to 3 months (49.5 ± 14.6 episodes/h vs. 22.4 ± 13.6 episodes/h of sleep; p < 0.0001; 95% confidence interval for change: -32.3 to -21.9). Central apnea index, oxygenation, and arousals significantly improved. Favorable effects on quality of life and sleepiness were noted. In patients with heart failure, the Minnesota Living With Heart Failure Questionnaire score significantly improved. Device- or procedure-related serious adverse events occurred in 26% of patients through 6 months post therapy initiation, predominantly due to lead repositioning early in the study. Therapy was well tolerated. Efficacy was maintained at 6 months. Transvenous, unilateral phrenic nerve stimulation appears safe and effective for treating CSA. These findings should be confirmed in a prospective, randomized, controlled trial. (Chronic Evaluation of Respicardia Therapy; NCT01124370). Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Proposal for a functional classification system of heart failure in patients with end-stage renal disease: proceedings of the acute dialysis quality initiative (ADQI) XI workgroup.

PubMed

Chawla, Lakhmir S; Herzog, Charles A; Costanzo, Maria Rosa; Tumlin, James; Kellum, John A; McCullough, Peter A; Ronco, Claudio

2014-04-08

Structural heart disease is highly prevalent in patients with chronic kidney disease requiring dialysis. More than 80% of patients with end-stage renal disease (ESRD) are reported to have cardiovascular disease. This observation has enormous clinical relevance because the leading causes of death for patients with ESRD are of cardiovascular disease etiology, including heart failure, myocardial infarction, and sudden cardiac death. The 2 systems most commonly used to classify the severity of heart failure are the New York Heart Association (NYHA) functional classification and the American Heart Association (AHA)/American College of Cardiology (ACC) staging system. With rare exceptions, patients with ESRD who do not receive renal replacement therapy (RRT) develop signs and symptoms of heart failure, including dyspnea and edema due to inability of the severely diseased kidneys to excrete sodium and water. Thus, by definition, nearly all patients with ESRD develop a symptomatology consistent with heart failure if fluid removal by RRT is delayed. Neither the AHA/ACC heart failure staging nor the NYHA functional classification system identifies the variable symptomatology that patients with ESRD experience depending upon whether evaluation occurs before or after fluid removal by RRT. Consequently, the incidence, severity, and outcomes of heart failure in patients with ESRD are poorly characterized. The 11th Acute Dialysis Quality Initiative has identified this issue as a critical unmet need for the proper evaluation and treatment of heart failure in patients with ESRD. We propose a classification schema based on patient-reported dyspnea assessed both pre- and post-ultrafiltration, in conjunction with echocardiography. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Effects of unplanned treatment interruptions on HIV treatment failure - results from TAHOD.

PubMed

Jiamsakul, Awachana; Kerr, Stephen J; Ng, Oon Tek; Lee, Man Po; Chaiwarith, Romanee; Yunihastuti, Evy; Van Nguyen, Kinh; Pham, Thuy Thanh; Kiertiburanakul, Sasisopin; Ditangco, Rossana; Saphonn, Vonthanak; Sim, Benedict L H; Merati, Tuti Parwati; Wong, Wingwai; Kantipong, Pacharee; Zhang, Fujie; Choi, Jun Yong; Pujari, Sanjay; Kamarulzaman, Adeeba; Oka, Shinichi; Mustafa, Mahiran; Ratanasuwan, Winai; Petersen, Boondarika; Law, Matthew; Kumarasamy, Nagalingeswaran

2016-05-01

Treatment interruptions (TIs) of combination antiretroviral therapy (cART) are known to lead to unfavourable treatment outcomes but do still occur in resource-limited settings. We investigated the effects of TI associated with adverse events (AEs) and non-AE-related reasons, including their durations, on treatment failure after cART resumption in HIV-infected individuals in Asia. Patients initiating cART between 2006 and 2013 were included. TI was defined as stopping cART for >1 day. Treatment failure was defined as confirmed virological, immunological or clinical failure. Time to treatment failure during cART was analysed using Cox regression, not including periods off treatment. Covariables with P < 0.10 in univariable analyses were included in multivariable analyses, where P < 0.05 was considered statistically significant. Of 4549 patients from 13 countries in Asia, 3176 (69.8%) were male and the median age was 34 years. A total of 111 (2.4%) had TIs due to AEs and 135 (3.0%) had TIs for other reasons. Median interruption times were 22 days for AE and 148 days for non-AE TIs. In multivariable analyses, interruptions >30 days were associated with failure (31-180 days HR = 2.66, 95%CI (1.70-4.16); 181-365 days HR = 6.22, 95%CI (3.26-11.86); and >365 days HR = 9.10, 95% CI (4.27-19.38), all P < 0.001, compared to 0-14 days). Reasons for previous TI were not statistically significant (P = 0.158). Duration of interruptions of more than 30 days was the key factor associated with large increases in subsequent risk of treatment failure. If TI is unavoidable, its duration should be minimised to reduce the risk of failure after treatment resumption. © 2016 John Wiley & Sons Ltd.

Failure Analysis of Cracked FS-85 Tubing and ASTAR-811C End Caps

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

ME Petrichek

2006-02-09

Failure analyses were performed on cracked FS-85 tubing and ASTAR-811C and caps which had been fabricated as components of biaxial creep specimens meant to support materials testing for the NR Space program. During the failure analyses of cracked FS-85 tubing, it was determined that the failure potentially could be due to two effects: possible copper contamination from the EDM (electro-discharge machined) recast layer and/or an insufficient solution anneal. to prevent similar failures in the future, a more formal analysis should be done after each processing step to ensure the quality of the material before further processing. During machining of themore » ASTAR-811FC rod to form end caps for biaxial creep specimens, linear defects were observed along the center portion of the end caps. These defects were only found in material that was processed from the top portion of the ingot. The linear defects were attributed to a probable residual ingot pipe that was not removed from the ingot. During the subsequent processing of the ingot to rod, the processing temperatures were not high enough to allow self healing of the ingot's residual pipe defect. To prevent this from occurring in the future, it is necessary to ensure that complete removal of the as-melted ingot pipe is verified by suitable non-destructive evaluation (NDE).« less

Light water reactor lower head failure analysis

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

Rempe, J.L.; Chavez, S.A.; Thinnes, G.L.

1993-10-01

This document presents the results from a US Nuclear Regulatory Commission-sponsored research program to investigate the mode and timing of vessel lower head failure. Major objectives of the analysis were to identify plausible failure mechanisms and to develop a method for determining which failure mode would occur first in different light water reactor designs and accident conditions. Failure mechanisms, such as tube ejection, tube rupture, global vessel failure, and localized vessel creep rupture, were studied. Newly developed models and existing models were applied to predict which failure mechanism would occur first in various severe accident scenarios. So that a broadermore » range of conditions could be considered simultaneously, calculations relied heavily on models with closed-form or simplified numerical solution techniques. Finite element techniques-were employed for analytical model verification and examining more detailed phenomena. High-temperature creep and tensile data were obtained for predicting vessel and penetration structural response.« less

Clinical models of cardiovascular regulation after weightlessness

NASA Technical Reports Server (NTRS)

Robertson, D.; Jacob, G.; Ertl, A.; Shannon, J.; Mosqueda-Garcia, R.; Robertson, R. M.; Biaggioni, I.

1996-01-01

After several days in microgravity, return to earth is attended by alterations in cardiovascular function. The mechanisms underlying these effects are inadequately understood. Three clinical disorders of autonomic function represent possible models of this abnormal cardiovascular function after spaceflight. They are pure autonomic failure, baroreflex failure, and orthostatic intolerance. In pure autonomic failure, virtually complete loss of sympathetic and parasympathetic function occurs along with profound and immediate orthostatic hypotension. In baroreflex failure, various degrees of debuffering of blood pressure occur. In acute and complete baroreflex failure, there is usually severe hypertension and tachycardia, while with less complete and more chronic baroreflex impairment, orthostatic abnormalities may be more apparent. In orthostatic intolerance, blood pressure fall is minor, but orthostatic symptoms are prominent and tachycardia frequently occurs. Only careful autonomic studies of human subjects in the microgravity environment will permit us to determine which of these models most closely reflects the pathophysiology brought on by a period of time in the microgravity environment.

X-33 Tank Failure During Autoclave Fabrication

NASA Technical Reports Server (NTRS)

Nettles, Alan T.; Munafo, Paul (Technical Monitor)

2001-01-01

During a repair cure cycle on tank #1 of the X-33 liquid hydrogen tanks, a skin to core disbond occurred. Both the inner skin and outer skin of the lobe #1 sandwich panel was noted to have been disbonded and cracked- An investigation was undertaken to determine the cause of this failure. The investigation consisted of reviewing all of the processing data and performing testing on the failed lobe #1, as well as the other lobes, which did not fail during the cure cycle. The tests consisted of residual stress measurements in one of the intact lobes and "plug-pulls" to assess skin to core strength on all of the remaining lobes. Results showed an extremely low bondline strength due to lack of proper filleting of the adhesive, in addition, tests showed a very rapid decrease in strength with increasing temperature, as well as a further decrease in strength with a larger number of cycles. Also, the honeycomb used was not vented so pressure could build up within the cells. All of these factors appeared to be contributors to the failure.

Influenza A non-H1N1 associated with acute respiratory failure and acute renal failure in a previously vaccinated cystic fibrosis patient

PubMed Central

Penteado, Louise Piva; Osório, Cecília Susin; Balbinotto, Antônio; Dalcin, Paulo de Tarso Roth

2018-01-01

In the 2014 - 2015 season, most influenza infections were due to A (H3N2) viruses. More than two-thirds of circulating A (H3N2) viruses are antigenically and genetically different (drifted) from the A (H3N2) vaccine component of 2014 - 2015 northern and southern Hemisphere seasonal influenza vaccines. The purpose of this paper is to report a case of seasonal influenza A non-H1N1 infection that occurred in June 2015 in an adult cystic fibrosis patient with severe lung disease previously vaccinated with the anti-flu trivalent vaccine. The patient evolved to respiratory and renal failure (without rhabdomyolysis) and was placed under mechanical ventilation and hemodialysis. The clinical outcome was positive after 39 days of hospital stay. In addition, the patient was clinically stable after 18 months of follow-up. With the recent advances in critical care medicine and in cystic fibrosis treatment, survival with advanced pulmonary disease in cystic fibrosis presents new questions and potential problems, which are still being formulated. PMID:29742226

Micromechanical and in situ shear testing of Al–SiC nanolaminate composites in a transmission electron microscope (TEM)

DOE PAGES

Mayer, Carl; Li, Nan; Mara, Nathan Allan; ...

2014-11-07

Nanolaminate composites show promise as high strength and toughness materials. Still, due to the limited volume of these materials, micron scale mechanical testing methods must be used to determine the properties of these films. To this end, a novel approach combining a double notch shear testing geometry and compression with a flat punch in a nanoindenter was developed to determine the mechanical properties of these films under shear loading. To further elucidate the failure mechanisms under shear loading, in situ TEM experiments were performed using a double notch geometry cut into the TEM foil. Aluminum layer thicknesses of 50nm andmore » 100nm were used to show the effect of constraint on the deformation. Higher shear strength was observed in the 50 nm sample (690±54 MPa) compared to the 100 nm sample (423±28.7 MPa). Additionally, failure occurred along the Al-SiC interface in the 50 nm sample as opposed to failure within the Al layer in the 100 nm sample.« less

Failure Mechanisms of Ni-H2 and Li-Ion Batteries Under Hypervelocity Impacts

NASA Technical Reports Server (NTRS)

Miller, J. E.; Lyons, F.; Christiansen, E. L.; Lear, D. M.

2017-01-01

Lithium-Ion (Li-Ion) batteries have yielded significant performance advantages for many industries, including the aerospace industry, and have been selected to replace nickel hydrogen (Ni-H2) batteries for the International Space Station (ISS) program to meet the energy storage demands. As the ISS uses its vast solar arrays to generate its power, the solar ar-rays meet their sunlit power demands and supply excess power to battery packs for power de-livery on the sun obscured phase of the approximate 90 minute low Earth orbit. These large battery packs are located on the exterior of the ISS, and as such, the battery packs are ex-posed to external environment threats like naturally occurring meteoroids and artificial orbital debris (MMOD). While the risks from these solid particle environments has been known and addressed to an acceptable risk of failure through shield design, it is not possible to completely eliminate the risk of loss of these assets on orbit due to MMOD, and as such, failure consequences to the ISS have been considered.

High phenobarbital clearance during continuous renal replacement therapy: a case report and pharmacokinetic analysis.

PubMed

Rosenborg, Staffan; Saraste, Lars; Wide, Katarina

2014-08-01

Phenobarbital is an old antiepileptic drug used in severe epilepsy. Despite this, little is written about the need for dose adjustments in renal replacement therapy. Most sources recommend a moderately increased dose guided by therapeutic drug monitoring.A 14 year old boy with nonketotic hyperglycinemia, a rare inborn error of metabolism, characterized by high levels of glycine, epilepsy, spasticity, and cognitive impairment, was admitted to the emergency department with respiratory failure after a few days of fever and cough. The boy was unconscious at admittance and had acute renal and hepatic failure.Due to the acute respiratory infection, hypoxic hepatic and renal failure occurred and the patient had a status epilepticus.The patient was intubated and mechanically ventilated. Continuous renal replacement therapy was initiated. Despite increased phenobarbital doses, therapeutic levels were not reached until the dose was increased to 500 mg twice daily. Therapeutic drug monitoring was performed in plasma and dialysate. Calculations revealed that phenobarbital was almost freely dialyzed.Correct dosing of drugs in patients on renal replacement therapy may need a multidisciplinary approach and guidance by therapeutic drug monitoring.

High Phenobarbital Clearance During Continuous Renal Replacement Therapy

PubMed Central

Rosenborg, Staffan; Saraste, Lars; Wide, Katarina

2014-01-01

Abstract Phenobarbital is an old antiepileptic drug used in severe epilepsy. Despite this, little is written about the need for dose adjustments in renal replacement therapy. Most sources recommend a moderately increased dose guided by therapeutic drug monitoring. A 14 year old boy with nonketotic hyperglycinemia, a rare inborn error of metabolism, characterized by high levels of glycine, epilepsy, spasticity, and cognitive impairment, was admitted to the emergency department with respiratory failure after a few days of fever and cough. The boy was unconscious at admittance and had acute renal and hepatic failure. Due to the acute respiratory infection, hypoxic hepatic and renal failure occurred and the patient had a status epilepticus. The patient was intubated and mechanically ventilated. Continuous renal replacement therapy was initiated. Despite increased phenobarbital doses, therapeutic levels were not reached until the dose was increased to 500 mg twice daily. Therapeutic drug monitoring was performed in plasma and dialysate. Calculations revealed that phenobarbital was almost freely dialyzed. Correct dosing of drugs in patients on renal replacement therapy may need a multidisciplinary approach and guidance by therapeutic drug monitoring. PMID:25101986

Electricity Breakdown Management for Sarawak Energy: Use of Condition-Based Equipment for Detection of Defective Insulator

NASA Astrophysics Data System (ADS)

Tan, J. K.; Abas, N.

2017-07-01

Managing electricity breakdown is vital since an outage causes economic losses for customers and the utility companies. However, electricity breakdown is unavoidable due to some internal or external factors beyond our control. Electricity breakdown on overhead lines tend occur more frequently because it is prone to external disturbances such as animal, overgrown vegetation and defective pole top accessories. In Sarawak Energy Berhad (SEB), majority of the network are composed of overhead lines and hence, is more prone to failure. Conventional method of equipment inspection and fault finding are not effective to quickly identify the root cause of failure. SEB has engaged the use of corona discharge camera as condition-based monitoring equipment to carry out condition based inspection on the line in order to diagnose the condition of the lines prior to failure. Experimental testing has been carried out to determine the correlation between the corona discharge count and the level of defect on line insulator. The result shall be tabulated and will be used as reference for future scanning and diagnostic on any defect on the lines.

[The value of radial shock wave therapy in the management of extended crural ulceration. Case report].

PubMed

Fekete, László; Nagy, György Ádám; Diamant, Péter Kamilló; Halmy, Csaba; Zentai, Agnes

2014-11-09

The authors present the history of a 36-year-old woman who had crural ulceration in the ventral side of the left lower limb due to venous circulatory failure for 5 years. In addition to the application of dressing adapted to the actual status of the wound, the authors applied an extracorporal shock wave therapy two times per week. After this treatment the size of the ulcer significantly decreased and it became suitable for mesh-graft cover. The patient is currently asymptomatic. The authors draw attention to the fact that the number of patients having crural ulcer is increasing in developed countries including Hungary. Lower limb ulcers occur in 1-5% of the adult population. Predisposing factors include older age and civilization hazards such as obesity, diabetes and sedentary lifestyle. The main cause of the disease is circulatory failure; venous insufficiency occurs in about two-thirds of the patients, arterial ischemia in 15% and diabetic angiopathy in 15% of the cases. Infections, metabolic diseases and immunological disorders may be also an underlying cause in a small number of patients. In several patients the causative factors occur simultaneously making difficult to find and effective treatment. Despite the use of numerous preventive and therapeutic protocols, treatment is usually long and does not always match expectations of the patients.

Seasonal and Local Characteristics of Lightning Outages of Power Distribution Lines in Hokuriku Area

NASA Astrophysics Data System (ADS)

Sugimoto, Hitoshi; Shimasaki, Katsuhiko

The proportion of the lightning outages in all outages on Japanese 6.6kV distribution lines is high with approximately 20 percent, and then lightning protections are very important for supply reliability of 6.6kV lines. It is effective for the lightning performance to apply countermeasures in order of the area where a large number of the lightning outages occur. Winter lightning occurs in Hokuriku area, therefore it is also important to understand the seasonal characteristics of the lightning outages. In summer 70 percent of the lightning outages on distribution lines in Hokuriku area were due to sparkover, such as power wire breakings and failures of pole-mounted transformers. However, in winter almost half of lightning-damaged equipments were surge arrester failures. The number of the lightning outages per lightning strokes detected by the lightning location system (LLS) in winter was 4.4 times larger than that in summer. The authors have presumed the occurrence of lightning outages from lightning stroke density, 50% value of lightning current and installation rate of lightning protection equipments and overhead ground wire by multiple regression analysis. The presumed results suggest the local difference in the lightning outages.

Comparison of endoscopy and barium swallow with marshmallow in dysphagia.

PubMed

Somers, S; Stevenson, G W; Thompson, G

1986-06-01

Forty-four patients with dysphagia were examined both by endoscopy and by barium swallow with a marshmallow bolus. In these patients 36 stenoses were found: 34 by radiology and 30 by endoscopy. The radiologic criteria for stenosis included arrest of the marshmallow in a manner to support a column of barium and reproduction of the patient's symptoms at the time this occurred. Radiologic false negative findings were partly due to an inability by patients to swallow an adequate marshmallow bolus; endoscopic failures were associated with small endoscopes and mild stenoses.

Importance of technical preparation of intraarterial shunts to prevent iatrogenic arterial injury during urgent procedures.

PubMed

Awad, Nadia; Choudry, Rashad; Durinka, Joel; Prabhu, Aparna; Dissin, Jonathan

2013-02-01

Although intraarterial shunting during carotid endarterectomy is a well-defined practice, its use remains controversial. Complication rates associated with shunt placement remain low, but may be underreported. When complications secondary to routine intraarterial shunting occur, they can cause significant morbidity or even mortality, emphasizing the importance of meticulous technique to prevent adverse outcomes. We report a case of internal carotid artery dissection and pseuedoaneurysm due to the technical failure of a safety device of an intraarterial shunt used during carotid endarterectomy.

Heart Failure with Preserved Ejection Fraction - Concept, Pathophysiology, Diagnosis and Challenges for Treatment.

PubMed

Miljkovik, Lidija Veterovska; Spiroska, Vera

2015-09-15

Heart failure (HF) with preserved left ventricular (LV) ejection fraction (HFpEF) occurs in 40 to 60% of the patients with HF, with a prognosis which is similar to HF with reduced ejection fraction (HFrEF). HFpEF pathophysiology is different from that of HFrEF, and has been characterized with diastolic dysfunction. Diastolic dysfunction has been defined with elevated left ventricular stiffness, prolonged iso-volumetric LV relaxation, slow LV filing and elevated LV end-diastolic pressure. Arterial hypertension occurs in majority cases with HFpEF worldwide. Patients are mostly older and obese. Diabetes mellitus and atrial fibrillation appear proportionally in a high frequency of patients with HFpEF. The HFpEF diagnosis is based on existence of symptoms and signs of heart failure, normal or approximately normal ejection and diagnosing of LV diastolic dysfunction by means of heart catheterization or Doppler echocardiography and/or elevated concentration of plasma natriuretic peptide. The present recommendations for HFpEF treatment include blood pressure control, heart chamber frequency control when atrial fibrillation exists, in some situations even coronary revascularization and an attempt for sinus rhythm reestablishment. Up to now, it is considered that no medication or a group of medications improve the survival of HFpEF patients. Due to these causes and the bad prognosis of the disorder, rigorous control is recommended of the previously mentioned precipitating factors for this disorder. This paper presents a universal review of the most important parameters which determine this disorder.

14 CFR 25.367 - Unsymmetrical loads due to engine failure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the engine compressor from the turbine or from loss of the turbine blades are considered to be... § 25.367 Unsymmetrical loads due to engine failure. (a) The airplane must be designed for the unsymmetrical loads resulting from the failure of the critical engine. Turbopropeller airplanes must be designed...

14 CFR 25.367 - Unsymmetrical loads due to engine failure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the engine compressor from the turbine or from loss of the turbine blades are considered to be... § 25.367 Unsymmetrical loads due to engine failure. (a) The airplane must be designed for the unsymmetrical loads resulting from the failure of the critical engine. Turbopropeller airplanes must be designed...

14 CFR 25.367 - Unsymmetrical loads due to engine failure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the engine compressor from the turbine or from loss of the turbine blades are considered to be... § 25.367 Unsymmetrical loads due to engine failure. (a) The airplane must be designed for the unsymmetrical loads resulting from the failure of the critical engine. Turbopropeller airplanes must be designed...

Performance of Oil Infrastructure during Hurricane Harvey

NASA Astrophysics Data System (ADS)

Bernier, C.; Kameshwar, S.; Padgett, J.

2017-12-01

Three major refining centers - Corpus Christi, Houston, and Beaumont/Port Arthur - were affected during Hurricane Harvey. Damage to oil infrastructure, especially aboveground storage tanks (ASTs), caused the release of more than a million gallons of hazardous chemicals in the environment. The objective of this presentation is to identify and gain a better understanding of the different damage mechanisms that occurred during Harvey in order to avoid similar failures during future hurricane events. First, a qualitative description of the damage suffered by ASTs during Hurricane Harvey is presented. Analysis of aerial imagery and incident reports indicate that almost all spills were caused by rainfall and the associated flooding. The largest spill was caused by two large ASTs that floated due to flooding in the Houston Ship Channel releasing 500,000 gallons of gasoline. The vulnerability of ASTs subjected to flooding was already well known and documented from previous storm events. In addition to flooding, Harvey also exposed the vulnerability of ASTs with external floating roof to extreme rainfall; more than 15 floating roofs sank or tilted due to rain water accumulation on them, releasing pollutants in the atmosphere. Secondly, recent fragility models developed by the authors are presented which allow structural vulnerability assessment of floating roofs during rainfall events and ASTs during flood events. The fragility models are then coupled with Harvey rainfall and flood empirical data to identify the conditions (i.e.: internal liquid height or density, drainage system design and efficiency, etc.) that could have led to the observed failures during Hurricane Harvey. Finally, the conditions causing tank failures are studied to propose mitigation measures to prevent future AST failures during severe storm, flood, or rainfall events.

Slope Stability Analysis of Mountainous/Hilly regions of Nepal: A case study of Bhotekoshi Hydropower site

NASA Astrophysics Data System (ADS)

Acharya, A.; Gautam, S.; Kafle, K. R.

2017-12-01

Nepal is a mountainous, developing country that straddles the boundary between the Indian and Himalayan tectonic plates. In Nepal, landslides represent a major constraint on development, causing high levels of economic loss and substantial number of fatalities each year. There is a general consensus that the impacts of landslides in mountainous countries such as Nepal are increasing with time due to unstable slopes. The present study deals with the field investigation of slope stability in mountainous/hilly region of Nepal. Among the natural hazards that occur in regularly in Nepal, flood and landslides due to unstable slopes are by far the serious ones. They claim many human lives every year and cause other damages such as destruction and blockage of highway, destruction of hydropower, losses of livestock, crops and agricultural land. Slope Mass Rating system and stereographic projection has been carried out for analysis of slope stability using standard formats and parameters. It has been found that there are few major discontinuities that play the role for the rock/soil slides around the area. The major discontinuities are 235°/67°. These joint sets play the main role to the plane as well as wedge failures around the area. The rock mass rating of the slope has been found to be 27 and the slope mass rating has been found to be 37.8. The obtained slope mass rating value lies on IV class (Bad) that represents unstable slope having planner or big wedge failure and needs to be corrective measures in the slope. From stereographic projection, wedge failure of the slope has been seen according to the conditions of slope failure.

Crack propagation and coalescence due to dual non-penetrating surface flaws and their effect on the strength of rock-like material

NASA Astrophysics Data System (ADS)

Xu, Jun; Zheng, Zheyuan; Xiao, Xiaochun; Li, Zhaoxia

2018-06-01

Non-penetrating surface flaws play a key role in the fracture process of rock-like material, and could cause localized collapse and even failure of the materials. Until now, the mechanism and the effect of surface crack propagation have remained unclear. In this paper, compression tests on gypsum (a soft rock material) are conducted to investigate crack propagation and coalescence due to non-penetrating surface flaws and their effect on the material strength. Specimens are tested under dual pre-existing surface flaws with various combinations of depth and spacing. The results show that when the pre-existing flaws are non-penetrating, the d/t ratio (flaw depth ratio, d is the pre-existing flaw cutting depth and t is the specimen thickness) and the spacing (the distance between the two flaw internal tips) have a strong influence on surface crack patterns and specimen strength. Few cracks emanate from the pre-existing flaws when the flaw depth ratio is equal to 1/3, and more cracks occur with the increase of the flaw depth ratio. When the pre-existing flaw penetrates completely through the specimen, the spacing has a small effect on the specimen strength. A larger flaw depth ratio could advance the occurrence of the peak load (PL) and result in a smaller specimen residual strength. The failure process of the specimen is divided into several stages featured by a stepped decline of the load value after PL, which is closely related to the initiation and propagation of secondary cracks. In addition, the spalling (failure of a portion of the surface caused by coalescence of cracks) can be regarded as indicating the failure of the specimen, and two possible types of spalling formation are briefly discussed.

Stress analysis of irradiated human tooth enamel using finite element methods

PubMed Central

Thiagarajan, Ganesh; Vizcarra, Bruno; Bodapudi, Venkata; Reed, Rachel; Seyedmahmoud, Rasoul; Wang, Yong; Gorski, Jeffrey P.; Walker, Mary P.

2017-01-01

The objectives of this project were to use finite element methods to determine how changes in the elastic modulus due to oral cancer therapeutic radiation alter the distribution of mechanical stresses in teeth and to determine if observed failures in irradiated teeth correlate with changes in mechanical stresses. A thin slice section finite element (FE) model was constructed from micro CT sections of a molar tooth using MIMICS and 3-Matic software. This model divides the tooth into three enamel regions, the dentin-enamel junction (DEJ) and dentin. The enamel elastic modulus was determined in each region using nano indentation for three experimental groups namely – control (non-radiated), in vitro irradiated (simulated radiotherapy following tooth extraction) and in vivo irradiated (extracted subsequent to oral cancer patient radiotherapy) teeth. Physiological loads were applied to the tooth models at the buccal and lingual cusp regions for all three groups (control, in vitro and in vivo). The principal tensile stress and the maximum shear stress were used to compare the results from different groups since it has been observed in previous studies that delamination of enamel from the underlying dentin was one of the major reasons for the failure of teeth following therapeutic radiation. From the FE data, we observed an increase in the principal tensile stress within the inner enamel region of in vivo irradiated teeth (9.97 ± 1.32 MPa) as compared to control/non-irradiated teeth (8.44 ± 1.57 MPa). Our model predicts that failure occurs at the inner enamel/DEJ interface due to extremely high tensile and maximum shear stresses in in vivo irradiated teeth which could be a cause of enamel delamination due to radiotherapy. PMID:29063816

Stress analysis of irradiated human tooth enamel using finite element methods.

PubMed

Thiagarajan, Ganesh; Vizcarra, Bruno; Bodapudi, Venkata; Reed, Rachel; Seyedmahmoud, Rasoul; Wang, Yong; Gorski, Jeffrey P; Walker, Mary P

2017-11-01

The objectives of this project were to use finite element methods to determine how changes in the elastic modulus due to oral cancer therapeutic radiation alter the distribution of mechanical stresses in teeth and to determine if observed failures in irradiated teeth correlate with changes in mechanical stresses. A thin slice section finite element (FE) model was constructed from micro CT sections of a molar tooth using MIMICS and 3-Matic software. This model divides the tooth into three enamel regions, the dentin-enamel junction (DEJ) and dentin. The enamel elastic modulus was determined in each region using nano indentation for three experimental groups namely - control (non-radiated), in vitro irradiated (simulated radiotherapy following tooth extraction) and in vivo irradiated (extracted subsequent to oral cancer patient radiotherapy) teeth. Physiological loads were applied to the tooth models at the buccal and lingual cusp regions for all three groups (control, in vitro and in vivo). The principal tensile stress and the maximum shear stress were used to compare the results from different groups since it has been observed in previous studies that delamination of enamel from the underlying dentin was one of the major reasons for the failure of teeth following therapeutic radiation. From the FE data, we observed an increase in the principal tensile stress within the inner enamel region of in vivo irradiated teeth (9.97 ± 1.32 MPa) as compared to control/non-irradiated teeth (8.44 ± 1.57 MPa). Our model predicts that failure occurs at the inner enamel/DEJ interface due to extremely high tensile and maximum shear stresses in in vivo irradiated teeth which could be a cause of enamel delamination due to radiotherapy.

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.

[Analysis of the failures of a cemented constrained liner model in patients with a high dislocation risk].

PubMed

Gallart, X; Gomez, J C; Fernández-Valencia, J A; Combalía, A; Bori, G; García, S; Rios, J; Riba, J

2014-01-01

To evaluate the short-term results of an ultra high molecular weight polyethylene retentive cup in patients at high risk of dislocation, either primary or revision surgery. Retrospective review of 38 cases in order to determine the rate of survival and failure analysis of a constrained cemented cup, with a mean follow-up of 27 months. We studied demographic data, complications, especially re-dislocations of the prosthesis and, also the likely causes of system failure analyzed. In 21.05% (8 cases) were primary surgery and 78.95% were revision surgery (30 cases). The overall survival rate by Kaplan-Meier method was 70.7 months. During follow-up 3 patients died due to causes unrelated to surgery and 2 infections occurred. 12 hips had at least two previous surgeries done. It wasn't any case of aseptic loosening. Four patients presented dislocation, all with a 22 mm head (P=.008). Our statistical analysis didn't found relationship between the abduction cup angle and implant failure (P=.22). The ultra high molecular weight polyethylene retentive cup evaluated in this series has provided satisfactory short-term results in hip arthroplasty patients at high risk of dislocation. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

Representational constraints on the development of memory and metamemory: a developmental-representational theory.

PubMed

Ceci, Stephen J; Fitneva, Stanka A; Williams, Wendy M

2010-04-01

Traditional accounts of memory development suggest that maturation of prefrontal cortex (PFC) enables efficient metamemory, which enhances memory. An alternative theory is described, in which changes in early memory and metamemory are mediated by representational changes, independent of PFC maturation. In a pilot study and Experiment 1, younger children failed to recognize previously presented pictures, yet the children could identify the context in which they occurred, suggesting these failures resulted from inefficient metamemory. Older children seldom exhibited such failure. Experiment 2 established that this was not due to retrieval-time recoding. Experiment 3 suggested that young children's representation of a picture's attributes explained their metamemory failure. Experiment 4 demonstrated that metamemory is age-invariant when representational quality is controlled: When stimuli were equivalently represented, age differences in memory and metamemory declined. These findings do not support the traditional view that as children develop, neural maturation permits more efficient monitoring, which leads to improved memory. These findings support a theory based on developmental-representational synthesis, in which constraints on metamemory are independent of neurological development; representational features drive early memory to a greater extent than previously acknowledged, suggesting that neural maturation has been overimputed as a source of early metamemory and memory failure. PsycINFO Database Record (c) 2010 APA, all rights reserved.

Stability of leaning column at Devils Tower National Monument, Wyoming

USGS Publications Warehouse

Harp, Edwin L.; Lindsay, Charles R.

2006-01-01

In response to reports from climbers that an 8-meter section (referred to as the leaning column) of the most popular climbing route on Devils Tower in northeastern Wyoming is now moving when being climbed, scientists from the U.S. Geological Survey inspected the site to determine the stability of the column and the underlying column that serves as a support pedestal. Evidence of a recent tensile spalling failure was observed on the pedestal surface immediately beneath the contact with the overlying leaning column. The spalling of a flake-shaped piece of the pedestal, probably due to the high stress concentration exerted by the weight of the leaning column along a linear contact with the pedestal, is likely causing the present movement of the leaning column. Although it is unlikely that climbers will dislodge the leaning column by their weight alone, the possibility exists that additional spalling failures may occur from the pedestal surface and further reduce the stability of the leaning column and result in its toppling. To facilitate detection of further spalling failures from the pedestal, its surface has been coated with a layer of paint. Any new failures from the pedestal could result in the leaning column toppling onto the climbing route or onto the section of the Tower trail below.

A preliminary assessment of the effects of heat flux distribution and penetration on the creep rupture of a reactor vessel lower head

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

Chu, T.Y.; Bentz, J.; Simpson, R.

1997-02-01

The objective of the Lower Head Failure (LHF) Experiment Program is to experimentally investigate and characterize the failure of the reactor vessel lower head due to thermal and pressure loads under severe accident conditions. The experiment is performed using 1/5-scale models of a typical PWR pressure vessel. Experiments are performed for various internal pressure and imposed heat flux distributions with and without instrumentation guide tube penetrations. The experimental program is complemented by a modest modeling program based on the application of vessel creep rupture codes developed in the TMI Vessel Investigation Project. The first three experiments under the LHF programmore » investigated the creep rupture of simulated reactor pressure vessels without penetrations. The heat flux distributions for the three experiments are uniform (LHF-1), center-peaked (LHF-2), and side-peaked (LHF-3), respectively. For all the experiments, appreciable vessel deformation was observed to initiate at vessel wall temperatures above 900K and the vessel typically failed at approximately 1000K. The size of failure was always observed to be smaller than the heated region. For experiments with non-uniform heat flux distributions, failure typically occurs in the region of peak temperature. A brief discussion of the effect of penetration is also presented.« less

Notch strengthening or weakening governed by transition of shear failure to normal mode fracture

PubMed Central

Lei, Xianqi; Li, Congling; Shi, Xinghua; Xu, Xianghong; Wei, Yujie

2015-01-01

It is generally observed that the existence of geometrical discontinuity like notches in materials will lead to strength weakening, as a resultant of local stress concentration. By comparing the influence of notches to the strength of three typical materials, aluminum alloys with intermediate tensile ductility, metallic glasses with no tensile ductility, and brittle ceramics, we observed strengthening in aluminum alloys and metallic glasses: Tensile strength of the net section in circumferentially notched cylinders increases with the constraint quantified by the ratio of notch depth over notch root radius; in contrast, the ceramic exhibit notch weakening. The strengthening in the former two is due to resultant deformation transition: Shear failure occurs in intact samples while samples with deep notches break in normal mode fracture. No such deformation transition was observed in the ceramic, and stress concentration leads to its notch weakening. The experimental results are confirmed by theoretical analyses and numerical simulation. The results reported here suggest that the conventional criterion to use brittleness and/or ductility to differentiate notch strengthening or weakening is not physically sound. Notch strengthening or weakening relies on the existence of failure mode transition and materials exhibiting shear failure while subjected to tension will notch strengthen. PMID:26022892

An assessment of wind tunnel test data on flexible thermal protection materials and results of new fatigue tests of threads

NASA Technical Reports Server (NTRS)

Coe, Charles F.

1985-01-01

Advanced Flexible Reusable Surface Insulation (AFRSI) was developed as a replacement for the low-temperature (white) tiles on the Space Shuttle. The first use of the AFRSI for an Orbiter flight was on the OMS POD of Orbiter (OV-099) for STS-6. Post flight examination after STS-6 showed that damage had occurred to the AFRSI during flight. The failure anomaly between previous wind-tunnel tests and STS-6 prompted a series of additional wind tunnel tests to gain an insight as to the cause of the failure. An assessment of all the past STS-6 wind tunnel tests pointed out the sensitivity of the test results to scaling of dynamic loads due to the difference of boundary layer thickness, and the material properties as a result of exposure to heating. The thread component of the AFRSI was exposed to fatigue testing using an apparatus that applied pulsating aerodynamic loads on the threads similar to the loads caused by an oscillating shock. Comparison of the mean values of the number-of-cycles to failure showed that the history of the thread was the major factor in its performance. The thread and the wind tunnel data suggests a mechanism of failure for the AFRSI.

A numerical procedure for failure mode detection of masonry arches reinforced with fiber reinforced polymeric materials

NASA Astrophysics Data System (ADS)

Galassi, S.

2018-05-01

In this paper a mechanical model of masonry arches strengthened with fibre-reinforced composite materials and the relevant numerical procedure for the analysis are proposed. The arch is modelled by using an assemblage of rigid blocks that are connected together and, also to the supporting structures, by mortar joints. The presence of the reinforcement, usually a sheet placed at the intrados or the extrados, prevents the occurrence of cracks that could activate possible collapse mechanisms, due to tensile failure of the mortar joints. Therefore, in a reinforced arch failure generally occurs in a different way from the URM arch. The numerical procedure proposed checks, as a function of an external incremental load, the inner stress state in the arch, in the reinforcement and in the adhesive layer. In so doing, it then provides a prediction of failure modes. Results obtained from experimental tests, carried out on four in-scale models performed in a laboratory, have been compared with those provided by the numerical procedure, implemented in ArchiVAULT, a software developed by the author. In this regard, the numerical procedure is an extension of previous works. Although additional experimental investigations are necessary, these former results confirm that the proposed numerical procedure is promising.

Acute kidney failure

MedlinePlus

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

Predicting Failure Under Laboratory Conditions: Learning the Physics of Slow Frictional Slip and Dynamic Failure

NASA Astrophysics Data System (ADS)

Rouet-Leduc, B.; Hulbert, C.; Riviere, J.; Lubbers, N.; Barros, K.; Marone, C.; Johnson, P. A.

2016-12-01

Forecasting failure is a primary goal in diverse domains that include earthquake physics, materials science, nondestructive evaluation of materials and other engineering applications. Due to the highly complex physics of material failure and limitations on gathering data in the failure nucleation zone, this goal has often appeared out of reach; however, recent advances in instrumentation sensitivity, instrument density and data analysis show promise toward forecasting failure times. Here, we show that we can predict frictional failure times of both slow and fast stick slip failure events in the laboratory. This advance is made possible by applying a machine learning approach known as Random Forests1(RF) to the continuous acoustic emission (AE) time series recorded by detectors located on the fault blocks. The RF is trained using a large number of statistical features derived from the AE time series signal. The model is then applied to data not previously analyzed. Remarkably, we find that the RF method predicts upcoming failure time far in advance of a stick slip event, based only on a short time window of data. Further, the algorithm accurately predicts the time of the beginning and end of the next slip event. The predicted time improves as failure is approached, as other data features add to prediction. Our results show robust predictions of slow and dynamic failure based on acoustic emissions from the fault zone throughout the laboratory seismic cycle. The predictions are based on previously unidentified tremor-like acoustic signals that occur during stress build up and the onset of macroscopic frictional weakening. We suggest that the tremor-like signals carry information about fault zone processes and allow precise predictions of failure at any time in the slow slip or stick slip cycle2. If the laboratory experiments represent Earth frictional conditions, it could well be that signals are being missed that contain highly useful predictive information. 1Breiman, L. Random forests. Machine Learning 45, 5-32 (2001). 2Rouet-Leduc, B. C. Hulbert, N. Lubbers, K. Barros and P. A. Johnson, Learning the physics of failure, in review (2016).

Fatigue failure of regenerator screens in a high frequency Stirling engine

NASA Technical Reports Server (NTRS)

Hull, David R.; Alger, Donald L.; Moore, Thomas J.; Scheuermann, Coulson M.

1988-01-01

Failure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and on removing the regenator screens, debris of unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 micron thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected it to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.

Theoretical model of impact damage in structural ceramics

NASA Technical Reports Server (NTRS)

Liaw, B. M.; Kobayashi, A. S.; Emery, A. G.

1984-01-01

This paper presents a mechanistically consistent model of impact damage based on elastic failures due to tensile and shear overloading. An elastic axisymmetric finite element model is used to determine the dynamic stresses generated by a single particle impact. Local failures in a finite element are assumed to occur when the primary/secondary principal stresses or the maximum shear stress reach critical tensile or shear stresses, respectively. The succession of failed elements thus models macrocrack growth. Sliding motions of cracks, which closed during unloading, are resisted by friction and the unrecovered deformation represents the 'plastic deformation' reported in the literature. The predicted ring cracks on the contact surface, as well as the cone cracks, median cracks, radial cracks, lateral cracks, and damage-induced porous zones in the interior of hot-pressed silicon nitride plates, matched those observed experimentally. The finite element model also predicted the uplifting of the free surface surrounding the impact site.

ToF-SIMS characterization of robust window material for use in diode pumped alkali lasers

NASA Astrophysics Data System (ADS)

Fletcher, Aaron; Turner, David; Fairchild, Steven; Rice, Christopher; Pitz, Gregory

2018-03-01

Developments in diode pumped alkali laser (DPAL) systems have been impeded because of the catastrophic failure of laser windows. The window's failure is caused by localized laser-induced heating of window material. This heating is believed to occur due to increases in absorption on or near the surface of the window. This increase is believed to be caused by either adsorption of carbon-based soot from the collisional gas or by the diffusion of rubidium into the bulk material. The work presented here will focus on the diffusion of Rb into the bulk window materials and will strive to identify a superior material to use as windows. The results of this research indicate that aluminum oxynitride (ALON), sapphire, MgAl2O4 (spinel), and ZrO2 are resistant to alkali-induced changes in optical properties.

Increased Resistance to Flow and Ventilator Failure Secondary to Faulty CO2 Absorbent Insert Not Detected During Automated Anesthesia Machine Check: A Case Report.

PubMed

Moreno-Duarte, Ingrid; Montenegro, Julio; Balonov, Konstantin; Schumann, Roman

2017-04-15

Most modern anesthesia workstations provide automated checkout, which indicates the readiness of the anesthesia machine. In this case report, an anesthesia machine passed the automated machine checkout. Minutes after the induction of general anesthesia, we observed a mismatch between the selected and delivered tidal volumes in the volume auto flow mode with increased inspiratory resistance during manual ventilation. Endotracheal tube kinking, circuit obstruction, leaks, and patient-related factors were ruled out. Further investigation revealed a broken internal insert within the CO2 absorbent canister that allowed absorbent granules to cause a partial obstruction to inspiratory and expiratory flow triggering contradictory alarms. We concluded that even when the automated machine checkout indicates machine readiness, unforeseen equipment failure due to unexpected events can occur and require providers to remain vigilant.

Establishment of design criteria for acceptable failure modes and fail safe considerations for the space shuttle structural system

NASA Technical Reports Server (NTRS)

Westrup, R. W.

1972-01-01

Investigations of fatigue life, and safe-life and fail-safe design concepts as applied to space shuttle structure are summarized. The results are evaluated to select recommended structural design criteria to provide assurance that premature failure due to propagation of undetected crack-like defects will not occur during shuttle operational service. The space shuttle booster, GDC configuration B-9U, is selected as the reference vehicle. Structural elements used as basis of detail analyses include wing spar caps, vertical stabilizer skins, crew compartment skin, orbiter support frame, and propellant tank shell structure. Fatigue life analyses of structural elements are performed to define potential problem areas and establish upper limits of operating stresses. Flaw growth analyses are summarized in parametric form over a range of initial flaw types and sizes, operating stresses and service life requirements. Service life of 100 to 500 missions is considered.

Breeding biology and nesting success of palila

USGS Publications Warehouse

Pletschet, S.M.; Kelly, J.F.

1990-01-01

We studied the breeding biology of Palila (Loxioides bailleui ) at 85 nests from 20 April to 14 September 1988. Eggs were laid over a 139-day period and incubation averaged 16.6 days. The female incubated 85.2% of daylight hours and males fed incubating females. Modal clutch size was 2 (x super(-) = 2.0) and an average of 1.4 nestlings fledged per successful nest. Nestlings were in the nest an average of 25.3 days. Both females and males fed nestlings with the rate of feeding decreasing as the nestlings grew older. Palila nesting success was 25%, reduced primarily by hatching failure and depredation of nestlings. Hatching failure, due to inviable eggs or desertion, occurred in 41% of nests with eggs (55% of nest mortality). Egg depredation was rare (5% of nest mortality). Inbreeding and low food availability are postulated as the major causes for poor hatching success.

Colchicine triggered severe rhabdomyolysis after long-term low-dose simvastatin therapy: a case report.

PubMed

Frydrychowicz, Clara; Pasieka, Bastian; Pierer, Matthias; Mueller, Wolf; Petros, Sirak; Weidhase, Lorenz

2017-01-04

Rhabdomyolysis is a widely recognized yet rare complication in statin use. Rhabdomyolysis might be triggered by the prescription of high doses of statins or by statin accumulation due to interactions with concomitant medication. Muscle cell destruction as evidenced by myoglobin elevation can induce potentially life-threatening acute renal failure. We report a case of a 70-year-old obese white man with sudden onset of severe rhabdomyolysis with consecutive renal failure. His medication included low-dose simvastatin, which he had taken for 6 years up until the event. The statin was withdrawn immediately. After 3 days of veno-venous hemofiltration his renal function was completely restored. Clinicians in both primary and special care might be unaware that side effects of statins do occur even after a long uneventful statin medication; they should be advised not to exclude that possibility upfront, even if a patient has tolerated the medication for years.

Strength and failure of a damaged material

DOE PAGES

Cerreta, Ellen K.; Gray III, George T.; Trujillo, Carl P.; ...

2015-09-07

Under complex, dynamic loading conditions, damage can occur within a material. Should this damage not lead to catastrophic failure, the material can continue to sustain further loading. But, little is understood about how to represent the mechanical response of a material that has experienced dynamic loading leading to incipient damage. We examine this effect in copper. Copper is shock loaded to impart an incipient state of damage to the material. Thereafter compression and tensile specimens were sectioned from the dynamically damaged specimen to quantify the subsequent properties of the material in the region of intense incipient damage and in regionsmore » far from the damage. Finally, we observed that enhanced yield stresses result from the damaged material even over material, which has simply been shock loaded and not damaged. These results are rationalized in terms of stored plastic work due to the damage process.« less

Strength and failure of a damaged material

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

Cerreta, Ellen K.; Gray III, George T.; Trujillo, Carl P.

Under complex, dynamic loading conditions, damage can occur within a material. Should this damage not lead to catastrophic failure, the material can continue to sustain further loading. But, little is understood about how to represent the mechanical response of a material that has experienced dynamic loading leading to incipient damage. We examine this effect in copper. Copper is shock loaded to impart an incipient state of damage to the material. Thereafter compression and tensile specimens were sectioned from the dynamically damaged specimen to quantify the subsequent properties of the material in the region of intense incipient damage and in regionsmore » far from the damage. Finally, we observed that enhanced yield stresses result from the damaged material even over material, which has simply been shock loaded and not damaged. These results are rationalized in terms of stored plastic work due to the damage process.« less

A review on prognostics and health monitoring of Li-ion battery

NASA Astrophysics Data System (ADS)

Zhang, Jingliang; Lee, Jay

2011-08-01

The functionality and reliability of Li-ion batteries as major energy storage devices have received more and more attention from a wide spectrum of stakeholders, including federal/state policymakers, business leaders, technical researchers, environmental groups and the general public. Failures of Li-ion battery not only result in serious inconvenience and enormous replacement/repair costs, but also risk catastrophic consequences such as explosion due to overheating and short circuiting. In order to prevent severe failures from occurring, and to optimize Li-ion battery maintenance schedules, breakthroughs in prognostics and health monitoring of Li-ion batteries, with an emphasis on fault detection, correction and remaining-useful-life prediction, must be achieved. This paper reviews various aspects of recent research and developments in Li-ion battery prognostics and health monitoring, and summarizes the techniques, algorithms and models used for state-of-charge (SOC) estimation, current/voltage estimation, capacity estimation and remaining-useful-life (RUL) prediction.

Instrument Failures for the da Vinci Surgical System: a Food and Drug Administration MAUDE Database Study.

PubMed

Friedman, Diana C W; Lendvay, Thomas S; Hannaford, Blake

2013-05-01

Our goal was to analyze reported instances of the da Vinci robotic surgical system instrument failures using the FDA's MAUDE (Manufacturer and User Facility Device Experience) database. From these data we identified some root causes of failures as well as trends that may assist surgeons and users of the robotic technology. We conducted a survey of the MAUDE database and tallied robotic instrument failures that occurred between January 2009 and December 2010. We categorized failures into five main groups (cautery, shaft, wrist or tool tip, cable, and control housing) based on technical differences in instrument design and function. A total of 565 instrument failures were documented through 528 reports. The majority of failures (285) were of the instrument's wrist or tool tip. Cautery problems comprised 174 failures, 76 were shaft failures, 29 were cable failures, and 7 were control housing failures. Of the reports, 10 had no discernible failure mode and 49 exhibited multiple failures. The data show that a number of robotic instrument failures occurred in a short period of time. In reality, many instrument failures may go unreported, thus a true failure rate cannot be determined from these data. However, education of hospital administrators, operating room staff, surgeons, and patients should be incorporated into discussions regarding the introduction and utilization of robotic technology. We recommend institutions incorporate standard failure reporting policies so that the community of robotic surgery companies and surgeons can improve on existing technologies for optimal patient safety and outcomes.

A statistical overview of mass movement characteristics on the North American Atlantic outer continental margin

USGS Publications Warehouse

Booth, James S.; O'Leary, Dennis W.

1992-01-01

An analysis of 179 mass movements on the North American Atlantic continental slope and upper rise shows that slope failures have occurred throughout the geographic extent of the outer margin. Although the slope failures show no striking affinity for a particular depth as an origination level, there is a broad, primary mode centered at about 900 m. The resulting slides terminate at almost all depths and have a primary mode at 1100 m, but the slope/rise boundary (at 2200 m) also is an important mode. Slope failures have occurred at declivities ranging from 1° to 30° (typically, 4°); the resultant mass movement deposits vary in width from 0.2 to 50 km (typically, 1-2 km) and in length from 0.3 to 380 km (typically, 2–4 km), and they have been reported to be as thick as 650 m. On a numeric basis, mass movements are slightly more prevalent on open slopes than in other physiographic settings, and both translational and rotational failure surfaces are common. The typical mass movement is disintegrative in nature. Open slope slides tend to occur at lower slope angles and are larger than canyon slides. Further, large‐scale slides rather than small‐scale slides tend to originate on gentle slopes (≍ 3-4°). Rotational slope failures appear to have a slightly greater chance of occurring in canyons, but there is no analogous bias associated with translational failures. Similarly, disintegrative slides seem more likely to be associated with rotational slope failures than translational ones and are longer than their nondisintegrative counterparts. The occurrence of such a variety of mass movements at low declivities implies that a regional failure mechanism has prevailed. We suggest that earthquakes or, perhaps in some areas, gas hydrates are the most likely cause of the slope failures.

Acute liver failure in Cuban children.

PubMed

Silverio, César E; Smithen-Romany, Chleo Y; Hondal, Norma I; Díaz, Hetzel O; Castellanos, Marlen I; Sosa, Oramis

2015-01-01

Acute liver failure is rare in pediatric patients and is one of the most challenging medical emergencies due to its prognostic and therapeutic implications. The best scientific evidence worldwide comes from multicenter studies in developed countries. In Cuba, there are no prior studies of this disorder in children. Describe the main clinical features of Cuban children treated at a national referral center for acute liver failure, as defined by recognized diagnostic criteria for pediatric patients. A case series study was conducted comprising patients diagnosed with acute liver failure treated from 2005 to 2011 in the hepatology and liver transplant service at Havana's William Soler University Children's Hospital. Variables were age group, etiology of acute liver failure, grade of hepatic encephalopathy, blood chemistry variables, and clinical outcome (whether or not spontaneous recovery of liver function occurred). Associations between variables were assessed using contingency tables, and case fatality was calculated, as well as relative risk with its 95% confidence interval. The Mann-Whitney U test was used to compare means of laboratory test results. Median age of the 31 patients studied (14 boys and 17 girls) was 24 months (range 1-180). Time between symptom onset and diagnosis of acute liver failure was 25.1 days (SD 16.8). Infection was the most common etiology, present in 61.3% of cases (19/31); nonhepatotropic viruses, especially cytomegalovirus, predominated in infants. Spontaneous recovery occurred in 15 patients (48.4%), 3 (9.7%) received transplants, and 13 died, for a case fatality of 41.9%. Outcome was not associated with etiology (p = 0.106), but was statistically associated with degree of hepatic encephalopathy (p <0.01): 77.8% of patients (7/9) with grades III-IV encephalopathy died, for a relative risk of 4.0 (95% CI 1.15-13.8), versus 11.1% (1/9) with grade II or less encephalopathy. Cholesterol levels were significantly lower in patients who failed to recover spontaneously (p <0.01). Patients' clinical characteristics in this case series were similar to those described in developed countries.The fact that nonhepatotropic viruses (basically, cytomegalovirus in infants) are the main cause of acute liver failure in Cuban children calls for further epidemiologic study and identification of local underlying determinants of this phenomenon.

45 CFR 1355.36 - Withholding Federal funds due to failure to achieve substantial conformity or failure to...

Code of Federal Regulations, 2011 CFR

2011-10-01

... 45 Public Welfare 4 2011-10-01 2011-10-01 false Withholding Federal funds due to failure to... Section 1355.36 Public Welfare Regulations Relating to Public Welfare (Continued) OFFICE OF HUMAN... FAMILIES, FOSTER CARE MAINTENANCE PAYMENTS, ADOPTION ASSISTANCE, AND CHILD AND FAMILY SERVICES GENERAL...

45 CFR 1355.36 - Withholding Federal funds due to failure to achieve substantial conformity or failure to...

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 4 2012-10-01 2012-10-01 false Withholding Federal funds due to failure to... Section 1355.36 Public Welfare Regulations Relating to Public Welfare (Continued) OFFICE OF HUMAN... FAMILIES, FOSTER CARE MAINTENANCE PAYMENTS, ADOPTION ASSISTANCE, AND CHILD AND FAMILY SERVICES GENERAL...

45 CFR 1355.36 - Withholding Federal funds due to failure to achieve substantial conformity or failure to...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 4 2014-10-01 2014-10-01 false Withholding Federal funds due to failure to... Section 1355.36 Public Welfare Regulations Relating to Public Welfare (Continued) OFFICE OF HUMAN... FAMILIES, FOSTER CARE MAINTENANCE PAYMENTS, ADOPTION ASSISTANCE, AND CHILD AND FAMILY SERVICES GENERAL...

High-throughput sequencing: a failure mode analysis.

PubMed

Yang, George S; Stott, Jeffery M; Smailus, Duane; Barber, Sarah A; Balasundaram, Miruna; Marra, Marco A; Holt, Robert A

2005-01-04

Basic manufacturing principles are becoming increasingly important in high-throughput sequencing facilities where there is a constant drive to increase quality, increase efficiency, and decrease operating costs. While high-throughput centres report failure rates typically on the order of 10%, the causes of sporadic sequencing failures are seldom analyzed in detail and have not, in the past, been formally reported. Here we report the results of a failure mode analysis of our production sequencing facility based on detailed evaluation of 9,216 ESTs generated from two cDNA libraries. Two categories of failures are described; process-related failures (failures due to equipment or sample handling) and template-related failures (failures that are revealed by close inspection of electropherograms and are likely due to properties of the template DNA sequence itself). Preventative action based on a detailed understanding of failure modes is likely to improve the performance of other production sequencing pipelines.

Risk of Performance and Behavioral Health Decrements Due to Inadequate Cooperation, Coordination, Communication, and Psychosocial Adaptation within a Team

NASA Technical Reports Server (NTRS)

Landon, Lauren Blackwell; Vessey, William B.; Barrett, Jamie D.

2015-01-01

A team is defined as: "two or more individuals who interact socially and adaptively, have shared or common goals, and hold meaningful task interdependences; it is hierarchically structured and has a limited life span; in it expertise and roles are distributed; and it is embedded within an organization/environmental context that influences and is influenced by ongoing processes and performance outcomes" (Salas, Stagl, Burke, & Goodwin, 2007, p. 189). From the NASA perspective, a team is commonly understood to be a collection of individuals that is assigned to support and achieve a particular mission. Thus, depending on context, this definition can encompass both the spaceflight crew and the individuals and teams in the larger multi-team system who are assigned to support that crew during a mission. The Team Risk outcomes of interest are predominantly performance related, with a secondary emphasis on long-term health; this is somewhat unique in the NASA HRP in that most Risk areas are medically related and primarily focused on long-term health consequences. In many operational environments (e.g., aviation), performance is assessed as the avoidance of errors. However, the research on performance errors is ambiguous. It implies that actions may be dichotomized into "correct" or "incorrect" responses, where incorrect responses or errors are always undesirable. Researchers have argued that this dichotomy is a harmful oversimplification, and it would be more productive to focus on the variability of human performance and how organizations can manage that variability (Hollnagel, Woods, & Leveson, 2006) (Category III1). Two problems occur when focusing on performance errors: 1) the errors are infrequent and, therefore, difficult to observe and record; and 2) the errors do not directly correspond to failure. Research reveals that humans are fairly adept at correcting or compensating for performance errors before such errors result in recognizable or recordable failures. Astronauts are notably adept high performers. Most failures are recorded only when multiple, small errors occur and humans are unable to recognize and correct or compensate for these errors in time to prevent a failure (Dismukes, Berman, Loukopoulos, 2007) (Category III). More commonly, observers record variability in levels of performance. Some teams commit no observable errors but fail to achieve performance objectives or perform only adequately, while other teams commit some errors but perform spectacularly. Successful performance, therefore, cannot be viewed as simply the absence of errors or the avoidance of failure Johnson Space Center (JSC) Joint Leadership Team, 2008). While failure is commonly attributed to making a major error, focusing solely on the elimination of error(s) does not significantly reduce the risk of failure. Failure may also occur when performance is simply insufficient or an effort is incapable of adjusting sufficiently to a contextual change (e.g., changing levels of autonomy).

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.

Investigating the soil removal characteristics of flexible tube coring method for lunar exploration

NASA Astrophysics Data System (ADS)

Tang, Junyue; Quan, Qiquan; Jiang, Shengyuan; Liang, Jieneng; Lu, Xiangyong; Yuan, Fengpei

2018-02-01

Compared with other technical solutions, sampling the planetary soil and returning it back to Earth may be the most direct method to seek the evidence of extraterrestrial life. To keep sample's stratification for further analyzing, a novel sampling method called flexible tube coring has been adopted for China future lunar explorations. Given the uncertain physical properties of lunar regolith, proper drilling parameters should be adjusted immediately in piercing process. Otherwise, only a small amount of core could be sampled and overload drilling faults could occur correspondingly. Due to the fact that the removed soil is inevitably connected with the cored soil, soil removal characteristics may have a great influence on both drilling loads and coring results. To comprehend the soil removal characteristics, a non-contact measurement was proposed and verified to acquire the coring and removal results accurately. Herein, further more experiments in one homogenous lunar regolith simulant were conducted, revealing that there exists a sudden core failure during the sampling process and the final coring results are determined by the penetration per revolution index. Due to the core failure, both drilling loads and soil's removal states are also affected thereby.

Structural Properties of EB-Welded AlSi10Mg Thin-Walled Pressure Vessels Produced by AM-SLM Technology

NASA Astrophysics Data System (ADS)

Nahmany, Moshe; Stern, Adin; Aghion, Eli; Frage, Nachum

2017-10-01

Additive manufacturing of metals by selective laser melting (AM-SLM) is hampered by significant limitations in product size due to the limited dimensions of printing trays. Electron beam welding (EBW) is a well-established process that results in relatively minor metallurgical modifications in workpieces due to the ability of EBW to pass high-density energy to the related substance. The present study aims to evaluate structural properties of EB-welded AlSi10Mg thin-walled pressure vessels produced from components prepared by SLM technology. Following the EB welding process, leak and burst tests were conducted, as was fractography analysis. The welded vessels showed an acceptable holding pressure of 30 MPa, with a reasonable residual deformation up to 2.3% and a leak rate better than 1 × 10-8 std-cc s-1 helium. The failures that occurred under longitudinal stresses reflected the presence of two weak locations in the vessels, i.e., the welded joint region and the transition zone between the vessel base and wall. Fractographic analysis of the fracture surfaces of broken vessels displayed the ductile mode of the rupture, with dimples of various sizes, depending on the failure location.

Effects of unplanned treatment interruptions on HIV treatment failure– results from TAHOD

PubMed Central

Jiamsakul, Awachana; Kerr, Stephen J.; Ng, Oon Tek; Lee, Man Po; Chaiwarith, Romanee; Yunihastuti, Evy; Van Nguyen, Kinh; Pham, Thuy Thanh; Kiertiburanakul, Sasisopin; Ditangco, Rossana; Saphonn, Vonthanak; Sim, Benedict L. H.; Merati, Tuti Parwati; Wong, Wingwai; Kantipong, Pacharee; Zhang, Fujie; Choi, Jun Yong; Pujari, Sanjay; Kamarulzaman, Adeeba; Oka, Shinichi; Mustafa, Mahiran; Ratanasuwan, Winai; Petersen, Boondarika; Law, Matthew; Kumarasamy, Nagalingeswaran

2016-01-01

Objectives Treatment interruptions (TI) of combination antiretroviral therapy (cART) are known to lead to unfavourable treatment outcomes but do still occur in resource-limited settings. We investigated the effects of TI associated with adverse events (AEs) and non-AE-related reasons, including their durations, on treatment failure after cART resumption in HIV-infected individuals in Asia. Methods Patients initiating cART between 2006-2013 were included. TI was defined as stopping cART for >1 day. Treatment failure was defined as confirmed virological, immunological or clinical failure. Time to treatment failure during cART was analysed using Cox regression, not including periods off treatment. Co-variables with p<0.10 in univariable analyses were included in multivariable analyses, where p<0.05 was considered statistically significant. Results Of 4549 patients from 13 countries in Asia, 3176 (69.8%) were male and the median age was 34 years. A total of 111 (2.4%) had TIs due to AEs and 135 (3.0%) had TIs for other reasons. Median interruption times were 22 days for AE and 148 days for non-AE TIs. In multivariable analyses, interruptions >30 days were associated with failure (31-180 days HR=2.66, 95%CI (1.70-4.16); 181-365 days HR=6.22, 95%CI (3.26-11.86); and >365 days HR=9.10, 95% CI (4.27-19.38), all p<0.001, compared to 0-14 days). Reasons for previous TI were not statistically significant (p=0.158). Conclusions Duration of interruptions of more than 30 days was the key factor associated with large increases in subsequent risk of treatment failure. If TI is unavoidable, its duration should be minimised to reduce the risk of failure after treatment resumption. PMID:26950901

Reward system and temporal pole contributions to affective evaluation during a first person shooter video game

PubMed Central

2011-01-01

Background Violent content in video games evokes many concerns but there is little research concerning its rewarding aspects. It was demonstrated that playing a video game leads to striatal dopamine release. It is unclear, however, which aspects of the game cause this reward system activation and if violent content contributes to it. We combined functional Magnetic Resonance Imaging (fMRI) with individual affect measures to address the neuronal correlates of violence in a video game. Results Thirteen male German volunteers played a first-person shooter game (Tactical Ops: Assault on Terror) during fMRI measurement. We defined success as eliminating opponents, and failure as being eliminated themselves. Affect was measured directly before and after game play using the Positive and Negative Affect Schedule (PANAS). Failure and success events evoked increased activity in visual cortex but only failure decreased activity in orbitofrontal cortex and caudate nucleus. A negative correlation between negative affect and responses to failure was evident in the right temporal pole (rTP). Conclusions The deactivation of the caudate nucleus during failure is in accordance with its role in reward-prediction error: it occurred whenever subject missed an expected reward (being eliminated rather than eliminating the opponent). We found no indication that violence events were directly rewarding for the players. We addressed subjective evaluations of affect change due to gameplay to study the reward system. Subjects reporting greater negative affect after playing the game had less rTP activity associated with failure. The rTP may therefore be involved in evaluating the failure events in a social context, to regulate the players' mood. PMID:21749711

Destructive Single-Event Failures in Diodes

NASA Technical Reports Server (NTRS)

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

2013-01-01

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

Epidemiology of central sleep apnoea in heart failure.

PubMed

Naughton, Matthew T

2016-03-01

Central sleep apnoea occurs in about a third of patients with reduced systolic heart failure and is a marker of increased mortality. Such patients usually are older males with advanced heart failure (i.e., high pulmonary wedge pressure), often in atrial fibrillation, with evidence of hyperventilation (i.e., low PaCO2) in the absence of hypoxemia. Characteristically, ventilation waxes and wanes in a sinusoidal pattern, with mild hypoxemia, occurring in the lighter levels of sleep usually when supine. Snoring may also occur in central sleep apnoea, often at the peak of hyperventilation, sometimes contributing to the confusion or overlap with obstructive sleep apnoea. Central sleep apnoea is associated with orthopnoea, paroxysmal nocturnal dyspnoea and an oscillatory respiratory pattern with an incremental cardiopulmonary exercise study. Importantly, heart failure therapies (e.g., afterload reduction, diuresis, pacemakers, transplantation) attenuate central sleep apnoea. Night to night variability in severity of central sleep apnoea may occur with changes in patients' posture during sleep (less severe when sleeping on-side or upright). Crown Copyright © 2016. Published by Elsevier Ireland Ltd. All rights reserved.

Impact of tachycardia and sympathetic stimulation by cold pressor test on cardiac diastology and arterial function in elderly females.

PubMed

Johnson, Jonas; Håkansson, Felicia; Shahgaldi, Kambiz; Manouras, Aristomenis; Norman, Mikael; Sahlén, Anders

2013-04-01

Abnormal vascular-ventricular coupling has been suggested to contribute to heart failure with preserved ejection fraction in elderly females. Failure to increase stroke volume (SV) during exercise occurs in parallel with dynamic changes in arterial physiology leading to increased afterload. Such adverse vascular reactivity during stress may reflect either sympathoexcitation or be due to tachycardia. We hypothesized that afterload elevation induces SV failure by transiently attenuating left ventricular relaxation, a phenomenon described in animal research. The respective roles of tachycardia and sympathoexcitation were investigated in n = 28 elderly females (70 ± 4 yr) carrying permanent pacemakers. At rest, during atrial tachycardia pacing (ATP; 100 min(-1)) and during cold pressor test (hand immersed in ice water), we performed Doppler echocardiography (maximal untwist rate analyzed by speckle tracking imaging of rotational mechanics) and arterial tonometry (arterial stiffness estimated as augmentation index). Estimation of arterial compliance was based on an exponential relationship between arterial pressure and volume. We found that ATP produced central hypovolemia and a reduction in SV which was larger in patients with stiffer arteries (higher augmentation index). There was an associated adverse response of arterial compliance and vascular resistance during ATP and cold pressor test, causing an overall increase in afterload, but nonetheless enhanced maximal rate of untwist and no evidence of afterload-dependent failure of relaxation. In conclusion, tachycardia and cold provocation in elderly females produces greater vascular reactivity and SV failure in the presence of arterial stiffening, but SV failure does not arise secondary to afterload-dependent attenuation of relaxation.

Sleep in heart failure.

PubMed

Naughton, Matthew T; Lorenzi-Filho, Geraldo

2009-01-01

Sleep plays a large role in patients with heart failure. In normal subjects, sleep is usually in a supine position with reduced sympathetic drive, elevated vagal tone and as such a relatively lower cardiac output and minute ventilation, allowing for recuperation. Patients with heart failure may not experience the same degree of autonomic activity change and the supine position may place a large strain on the pulmonary system. More than half of all heart failure patients have one of two types of sleep apnea: either obstructive or central sleep apnea. Some patients have both types. Obstructive sleep apnea is likely to be a cause of heart failure due to large negative intrathoracic pressures, apnea related hypoxemia and hypercapnia, terminated by an arousal and surge in systemic blood pressure associated with endothelial damage and resultant premature atherosclerosis. Reversal of obstructive sleep apnea improves blood pressure, systolic contraction and autonomic dysfunction however mortality studies are lacking. Central sleep apnea with Cheyne Stokes pattern of respiration (CSA-CSR) occurs as a result of increased central controller (brainstem driving ventilation) and plant (ventilation driving CO2) gain in the setting of a delayed feed back (i.e., low cardiac output). It is thought this type of apnea is a result of moderately to severely impaired cardiac function and is possibly indicative of high mortality. Treatment of CSA-CSR is best undertaken by treating the underlying cardiac condition which may include with medications, pacemakers, transplantation or continuous positive airway pressure (CPAP). In such patients CPAP exerts unique effects to assist cardiac function and reduce pulmonary edema. Whether CPAP improves survival in this heart failure population remains to be determined.

Predicting failure: acoustic emission of berlinite under compression.

PubMed

Nataf, Guillaume F; Castillo-Villa, Pedro O; Sellappan, Pathikumar; Kriven, Waltraud M; Vives, Eduard; Planes, Antoni; Salje, Ekhard K H

2014-07-09

Acoustic emission has been measured and statistical characteristics analyzed during the stress-induced collapse of porous berlinite, AlPO4, containing up to 50 vol% porosity. Stress collapse occurs in a series of individual events (avalanches), and each avalanche leads to a jerk in sample compression with corresponding acoustic emission (AE) signals. The distribution of AE avalanche energies can be approximately described by a power law p(E)dE = E(-ε)dE (ε ~ 1.8) over a large stress interval. We observed several collapse mechanisms whereby less porous minerals show the superposition of independent jerks, which were not related to the major collapse at the failure stress. In highly porous berlinite (40% and 50%) an increase of energy emission occurred near the failure point. In contrast, the less porous samples did not show such an increase in energy emission. Instead, in the near vicinity of the main failure point they showed a reduction in the energy exponent to ~ 1.4, which is consistent with the value reported for compressed porous systems displaying critical behavior. This suggests that a critical avalanche regime with a lack of precursor events occurs. In this case, all preceding large events were 'false alarms' and unrelated to the main failure event. Our results identify a method to use pico-seismicity detection of foreshocks to warn of mine collapse before the main failure (the collapse) occurs, which can be applied to highly porous materials only.

Micromechanical investigation of ductile failure in Al 5083-H116 via 3D unit cell modeling

NASA Astrophysics Data System (ADS)

Bomarito, G. F.; Warner, D. H.

2015-01-01

Ductile failure is governed by the evolution of micro-voids within a material. The micro-voids, which commonly initiate at second phase particles within metal alloys, grow and interact with each other until failure occurs. The evolution of the micro-voids, and therefore ductile failure, depends on many parameters (e.g., stress state, temperature, strain rate, void and particle volume fraction, etc.). In this study, the stress state dependence of the ductile failure of Al 5083-H116 is investigated by means of 3-D Finite Element (FE) periodic cell models. The cell models require only two pieces of information as inputs: (1) the initial particle volume fraction of the alloy and (2) the constitutive behavior of the matrix material. Based on this information, cell models are subjected to a given stress state, defined by the stress triaxiality and the Lode parameter. For each stress state, the cells are loaded in many loading orientations until failure. Material failure is assumed to occur in the weakest orientation, and so the orientation in which failure occurs first is considered as the critical orientation. The result is a description of material failure that is derived from basic principles and requires no fitting parameters. Subsequently, the results of the simulations are used to construct a homogenized material model, which is used in a component-scale FE model. The component-scale FE model is compared to experiments and is shown to over predict ductility. By excluding smaller nucleation events and load path non-proportionality, it is concluded that accuracy could be gained by including more information about the true microstructure in the model; emphasizing that its incorporation into micromechanical models is critical to developing quantitatively accurate physics-based ductile failure models.

Risk factors for oral methotrexate failure in patients with inflammatory polyarthritis: results from a UK prospective cohort study.

PubMed

Bluett, James; Sergeant, Jamie C; MacGregor, Alex J; Chipping, Jacqueline R; Marshall, Tarnya; Symmons, Deborah P M; Verstappen, Suzanne M M

2018-03-20

Oral methotrexate (MTX) is the first-line therapy for patients with rheumatoid arthritis (RA). However, approximately one quarter of patients discontinue MTX within 12 months. MTX failure, defined as MTX cessation or the addition of another anti-rheumatic drug, is usually due adverse event(s) and/or inefficacy. The aims of this study were to evaluate the rate and predictors of oral MTX failure. Subjects were recruited from the Norfolk Arthritis Register (NOAR), a primary care-based inception cohort of patients with early inflammatory polyarthritis (IP). Subjects were eligible if they commenced MTX as their first DMARD and were recruited between 2000 and 2008. Patient-reported reasons for MTX failure were recorded and categorised as adverse event, inefficacy or other. The addition of a second DMARD during the study period was categorised as failure due to inefficacy. Cox proportional hazards regression models were used to assess potential predictors of MTX failure, accounting for competing risks. A total of 431 patients were eligible. The probability of patients remaining on MTX at 2 years was 82%. Competing risk analysis revealed that earlier MTX failure due to inefficacy was associated with rheumatoid factor (RF) positivity, younger age at symptom onset and higher baseline disease activity (DAS-28). MTX cessation due to an adverse event was less likely in the RF-positive cohort. RF-positive inflammatory polyarthritis patients who are younger with higher baseline disease activity have an increased risk of MTX failure due to inefficacy. Such patients may require combination therapy as a first-line treatment.

On-Orbit Engineering and Vehicle Integration Poster Presentation

NASA Technical Reports Server (NTRS)

Heimerdinger, Madison

2014-01-01

One of the duties of the MER Managers is getting the consoles to review and sign Electronic Flight Notes (EFN) and Mission Action Requests (Chit) before they are due. Chits and EFNs and are accessible through the Mission Control Center - Houston (MCC-H) Gateway. Chits are the official means of documenting questions and answers, technical direction, real-time changes to Flight Rules (FR) and procedures, request for analysis, etc. between various consoles concerning on-orbit operations. EFNs are documents used by the Flight Control Team (FCT) to communicate precise details between console positions and manage real time changes to FR and Systems Operation Data File (SODF) procedures. On GMT 2013/345 the External Active Thermal Control System (EATCS) on the Columbus (COL) Moderate Temperature Loop (MTL) Interface Heat Exchanger (IFHX) shut down due to low temperatures. Over the next couple of days, the core temperature of COL MT IFHX dropped due to the failure of the Flow Control Valve (FCV). After the temperature drop was discovered, heaters were turned on to bring the temperatures back to nominal. After the incident occurred, a possible freeze threat was discovered that could have ruptured the heat exchanger. The COL MT IFHX rupturing would be considered a catastrophic failure and potentially result in a loss of the vehicle and/or the lives of the International Space Station (ISS) crew members

How Pore-Fluid Pressure due to Heavy Rainfall Influences Volcanic Eruptions, Example of 1998 and 2008 Eruptions of Cerro Azul (Galapagos)

NASA Astrophysics Data System (ADS)

Albino, F.; Amelung, F.; Gregg, P. M.

2016-12-01

About 30 worldwide seismic studies have shown a strong correlation between rainfall and earthquakes in the past 22 years (e.g. Costain and Bollinger, 2010). Such correlation has been explained by the phenomenon of hydro-seismicity via pore pressure diffusion: an increase of pore-fluid in the upper crust reduces the normal stress on faults, which can trigger shear failure. Although this pore pressure effect is widely known for earthquakes, this phenomenon and more broadly poro-elasticity process are not widely studied on volcanoes. However, we know from our previous works that tensile failures that open to propagate magma through the surface are also pore pressure dependent. We have demonstrated that an increase of pore pressure largely reduces the overpressure required to rupture the magma reservoir. We have shown that the pore pressure has more influence on reservoir stability than other parameters such as the reservoir depth or the edifice loading. Here, we investigate how small pore-fluid changes due to hydrothermal or aquifer refill during heavy rainfall may perturb the conditions of failure around magma reservoirs and, what is more, if these perturbations are enough to trigger magma intrusions. We quantify the pore pressure effect on magmatic system by combining 1) 1D pore pressure diffusion model to quantify how pore pressure changes from surface to depth after heavy rainfall events and 2) 2D poro-elastic numerical model to provide the evolution of failure conditions of the reservoir as a consequence of these pore pressure changes. Sensitivity analysis is also performed to characterize the influence on our results of the poro-elastic parameters (hydraulic diffusivity, permeability and porosity) and the geometry of the magma reservoir and the aquifer (depth, size, shape). Finally, we apply our methodology to Cerro Azul volcano (Galapagos) where both last eruptions (1998 and 2008) occurred just after heavy rainfall events, without any pre-eruptive inflation. In the event eruptions can be triggered by pore pressure changes in the crust, meteorological records and water table measurements are required to improve eruption's forecast, especially in regions where heavy rainfall events (typhoons, monsoons or hurricanes) frequently occur, such as in Indonesia, Philippines or Central America.

A Study of Failure Characteristics in Thermoplastic Composite Laminates Due to an Eccentric Circular Discontinuity

DTIC Science & Technology

1989-12-01

Bose, Ohio Appni’-sd for puauc t&cw 189 12 29 023 I [ AFIT /GAE /ENY/ 89D-06 A STUDY OF FAILURE CHARACTERISTICS IN THERMOPLASTIC COMPOSITE LAMINATES DUE...distribution unlimited I ,I AFIT / GAE / ENY /89D-06 A STUDY OF FAILURE CHARACTERISTICS IN THERMOPLASTIC COMPOSITE LAMINATES DUE TO AN ECCENTRIC CIRCULAR...the Flight Dynamics Laboratory. Dr. Sandhu provided me with an insight into composite materials, and testing techniques, that will benefit me for a

Structural health monitoring and damage evaluation for steel confined reinforced concrete column using the acoustic emission technique

NASA Astrophysics Data System (ADS)

Du, Fangzhu; Li, Dongsheng

2018-03-01

As a new kind of composite structures, the using of steel confined reinforced concrete column attract increasing attention in civil engineer. During the damage process, this new structure offers highly complex and invisible failure mechanism due to the combination effects of steel tubes, concrete, and steel rebar. Acoustic emission (AE) technique has been extensively studied in nondestructive testing (NDT) and is currently applied in civil engineering for structural health monitoring (SHM) and damage evaluation. In the present study, damage property and failure evolution of steel confined and unconfined reinforced concrete (RC) columns are investigated under quasi-static loading through (AE) signal. Significantly improved loading capacity and excellent energy dissipation characteristic demonstrated the practicality of that proposed structure. AE monitoring results indicated that the progressive deformation of the test specimens occur in three stages representing different damage conditions. Sentry function compares the logarithm ratio between the stored strain energy (Es) and the released acoustic energy (Ea); explicitly disclose the damage growth and failure mechanism of the test specimens. Other extended AE features including index of damage (ID), and relax ratio are calculated to quantitatively evaluate the damage severity and critical point. Complicated temporal evolution of different AE features confirms the potential importance of integrated analysis of two or more parameters. The proposed multi-indicators analysis is capable of revealing the damage growth and failure mechanism for steel confined RC columns, and providing critical warning information for structure failure.

Influence of implant location on the clinical outcomes of implant abutments: a systematic review and meta-analysis

PubMed Central

ElHoussiney, Amr G; Zhang, He; Song, Jinlin; Ji, Ping; Wang, Lu; Yang, Sheng

2018-01-01

Purpose To compare the failure events and incidence of complications of different abutment materials in anterior and posterior regions. Failure was defined as complete loss of the abutment requiring replacement by a new abutment. Materials and methods Electronic searches using PubMed/Medline and Google Scholar complemented with manual searches were performed with specific search terms. Searches were restricted to publications in English between January 2006 and March 2016. Results A total of 863 and 1,264 implants were inserted in the anterior and posterior regions, respectively, in a total of 1,529 patients. No titanium abutments failed in anterior or posterior regions. On the other hand, 1.6% of zirconia abutments failed in the anterior region and 1.5% failed in the posterior region. Technical complications occurred mostly in the posterior region and mostly involved zirconia abutment. Meta-analysis was possible only for zirconia-abutment failure, due to considerable heterogeneity of studies and outcome variables. No significant difference in failure rate was found between anterior and posterior zirconia abutments (risk ratio 1.53, 95% CI 0.49–4.77; P=0.47). Conclusion This systematic review and meta-analysis showed similar outcomes of different abutment materials when used in anterior and posterior regions in terms of failure events and biological and aesthetic complications. The only significant finding was the increased incidence of technical complications in the posterior region, mostly involving zirconia abutments. Abutment-screw loosening was the most common technical complication. PMID:29520162

Left atrial function in heart failure with impaired and preserved ejection fraction.

PubMed

Fang, Fang; Lee, Alex Pui-Wai; Yu, Cheuk-Man

2014-09-01

Left atrial structural and functional changes in heart failure are relatively ignored parts of cardiac assessment. This review illustrates the pathophysiological and functional changes in left atrium in heart failure as well as their prognostic value. Heart failure can be divided into those with systolic dysfunction and heart failure with preserved ejection fraction (HFPEF). Left atrial enlargement and dysfunction commonly occur in systolic heart failure, in particular, in idiopathic dilated cardiomyopathy. Atrial enlargement and dysfunction also carry important prognostic value in systolic heart failure, independently of known parameters such as left ventricular ejection fraction. In HFPEF, there is evidence of left atrial enlargement, impaired atrial compliance, and reduction of atrial pump function. This occurs not only at rest but also during exercise, indicating significant impairment of atrial contractile reserve. Furthermore, atrial dyssynchrony is common in HFPEF. These factors further contribute to the development of new onset or progression of atrial arrhythmias, in particular, atrial fibrillation. Left atrial function is an integral part of cardiac function and its structural and functional changes in heart failure are common. As changes of left atrial structure and function have different clinical implications in systolic heart failure and HFPEF, routine assessment is warranted.

PDC Bit Testing at Sandia Reveals Influence of Chatter in Hard-Rock Drilling

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

RAYMOND,DAVID W.

1999-10-14

Polycrystalline diamond compact (PDC) bits have yet to be routinely applied to drilling the hard-rock formations characteristic of geothermal reservoirs. Most geothermal production wells are currently drilled with tungsten-carbide-insert roller-cone bits. PDC bits have significantly improved penetration rates and bit life beyond roller-cone bits in the oil and gas industry where soft to medium-hard rock types are encountered. If PDC bits could be used to double current penetration rates in hard rock geothermal well-drilling costs could be reduced by 15 percent or more. PDC bits exhibit reasonable life in hard-rock wear testing using the relatively rigid setups typical of laboratorymore » testing. Unfortunately, field experience indicates otherwise. The prevailing mode of failure encountered by PDC bits returning from hard-rock formations in the field is catastrophic, presumably due to impact loading. These failures usually occur in advance of any appreciable wear that might dictate cutter replacement. Self-induced bit vibration, or ''chatter'', is one of the mechanisms that may be responsible for impact damage to PDC cutters in hard-rock drilling. Chatter is more severe in hard-rock formations since they induce significant dynamic loading on the cutter elements. Chatter is a phenomenon whereby the drillstring becomes dynamically unstable and excessive sustained vibrations occur. Unlike forced vibration, the force (i.e., weight on bit) that drives self-induced vibration is coupled with the response it produces. Many of the chatter principles derived in the machine tool industry are applicable to drilling. It is a simple matter to make changes to a machine tool to study the chatter phenomenon. This is not the case with drilling. Chatter occurs in field drilling due to the flexibility of the drillstring. Hence, laboratory setups must be made compliant to observe chatter.« less

Service Recovery in Marketing Education: It's What We Do that Counts

ERIC Educational Resources Information Center

Iyer, Rajesh; Muncy, James A.

2008-01-01

One thing that higher education has in common with other service providers is that service failures occur. There are times when students are negatively impacted by mistakes made in the classroom. An extensive body of literature has developed in the area of services marketing about what to do when such service failures occur. The current study…

Life prediction and mechanical reliability of NT551 silicon nitride

NASA Astrophysics Data System (ADS)

Andrews, Mark Jay

The inert strength and fatigue performance of a diesel engine exhaust valve made from silicon nitride (Si3N4) ceramic were assessed. The Si3N4 characterized in this study was manufactured by Saint Gobain/Norton Industrial Ceramics and was designated as NT551. The evaluation was made utilizing a probabilistic life prediction algorithm that combined censored test specimen strength data with a Weibull distribution function and the stress field of the ceramic valve obtained from finite element analysis. The major assumptions of the life prediction algorithm are that the bulk ceramic material is isotropic and homogeneous and that the strength-limiting flaws are uniformly distributed. The results from mechanical testing indicated that NT551 was not a homogeneous ceramic and that its strength were functions of temperature, loading rate, and machining orientation. Fractographic analysis identified four different failure modes; 2 were identified as inhomogeneities that were located throughout the bulk of NT551 and were due to processing operations. The fractographic analysis concluded that the strength degradation of NT551 observed from the temperature and loading rate test parameters was due to a change of state that occurred in its secondary phase. Pristine and engine-tested valves made from NT551 were loaded to failure and the inert strengths were obtained. Fractographic analysis of the valves identified the same four failure mechanisms as found with the test specimens. The fatigue performance and the inert strength of the Si3N 4 valves were assessed from censored and uncensored test specimen strength data, respectively. The inert strength failure probability predictions were compared to the inert strength of the Si3N4 valves. The inert strength failure probability predictions were more conservative than the strength of the valves. The lack of correlation between predicted and actual valve strength was due to the nonuniform distribution of inhomogeneities present in NT551. For the same reasons, the predicted and actual fatigue performance did not correlate well. The results of this study should not be considered a limitation of the life prediction algorithm but emphasize the requirement that ceramics be homogeneous and strength-limiting flaws uniformly distributed as a perquisite for accurate life prediction and reliability analyses.

Translation failure and medical reversal: Two sides to the same coin.

PubMed

Prasad, Vinay

2016-01-01

Translation failure occurs when the results of preclinical, observational and/or early phase studies fail to predict the results of well done (i.e. appropriately controlled, adequately powered, and properly conducted) phase III or randomised clinical trials. Some failures occur when promising basic science findings fail to replicate in human studies, while others happen when promising uncontrolled trial data show an exaggerated effect that vanishes in the setting of a randomised trial. Medical reversals occur when the results of preclinical, observational and/or early phase studies fail to predict the results of subsequent randomized clinical trials, but the practice has already gained widespread acceptance. Oncologic examples include bevacizumab and the use of autologous stem cell transplant in metastatic breast cancer. In a well-intentioned effort to reduce the rate of translation failure, oncologists must be careful that changes to regulatory processes and clinical trial design do not actually work to increase the approval of ineffective compounds. By trying to cure translation failure, we should be careful to avoid medical reversal. The rise of surrogate end-points and role of hard-wired bias in oncology trials suggest that we may be currently ignoring the simple fact that translation failure and medical reversal are two sides to the same coin. Published by Elsevier Ltd.

Fatigue failure of regenerator screens in a high frequency Stirling engine

NASA Technical Reports Server (NTRS)

Hull, David R.; Alger, Donald L.; Moore, Thomas J.; Scheuermann, Coulson M.

1987-01-01

Failure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and on removing the regenerator screens, debris of unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 micron thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain a 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected it to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.

Deformation and failure mechanism of secondary cell wall in Spruce late wood

NASA Astrophysics Data System (ADS)

Adusumalli, Ramesh-Babu; Raghavan, Rejin; Ghisleni, Rudy; Zimmermann, Tanja; Michler, Johann

2010-08-01

The deformation and failure of the secondary cell wall of Spruce wood was studied by in-situ SEM compression of micropillars machined by the focused ion beam technique. The cell wall exhibited yield strength values of approximately 160 MPa and large scale plasticity. High resolution SEM imaging post compression revealed bulging of the pillars followed by shear failure. With additional aid of cross-sectional analysis of the micropillars post compression, a model for deformation and failure mechanism of the cell wall has been proposed. The cell wall consists of oriented cellulose microfibrils with high aspect ratio embedded in a hemicellulose-lignin matrix. The deformation of the secondary wall occurs by asymmetric out of plane bulging because of buckling of the microfibrils. Failure of the cell wall following the deformation occurs by the formation of a shear or kink band.

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

Method to Determine the Stress-Strain Response of As-Formed Thin-Walled Tubular Structures Using a Flaring Apparatus

NASA Astrophysics Data System (ADS)

Jurendic, S.; Anderson, D.

2017-09-01

Finite element simulations are used extensively to refine the forming steps of draw and wall iron (DWI) aluminum bottles; therefore, accurate material data is required Unfortunately, the material properties of the base sheet cannot presently be used for simulation of the later forming stages due to preceding significant deformation (ironing) and thermal treatments. Measuring the stress-strain response using traditional methods (e.g. tensile test) becomes increasingly difficult at later stages of the bottle forming process due to a significant diameter reduction of the bottle neck from successive die-necking stages. Moreover, failure during forming tends to occur in the final deformation stages when the bottle opening is rolled over, creating a brim roll, at which point brim roll splits may occur. Knowledge of the stress-strain response prior to the roll over may lead to improved product design, reduced waste, and an optimized product. Therefore, this work details a flaring apparatus and data analysis method to determine the stress-strain response in the die-necked region of thin-walled aluminum bottles fabricated from AA3104 sheet metal.

Reliability and cost: A sensitivity analysis

NASA Technical Reports Server (NTRS)

Suich, Ronald C.; Patterson, Richard L.

1991-01-01

In the design phase of a system, how a design engineer or manager choose between a subsystem with .990 reliability and a more costly subsystem with .995 reliability is examined, along with the justification of the increased cost. High reliability is not necessarily an end in itself but may be desirable in order to reduce the expected cost due to subsystem failure. However, this may not be the wisest use of funds since the expected cost due to subsystem failure is not the only cost involved. The subsystem itself may be very costly. The cost of the subsystem nor the expected cost due to subsystem failure should not be considered separately but the total of the two costs should be maximized, i.e., the total of the cost of the subsystem plus the expected cost due to subsystem failure.

Exploratory Investigation of Failure Mechanisms in Transition Regions between Solid Laminates and X-cor(registered tm) Truss Sandwich

NASA Technical Reports Server (NTRS)

OBrien, T. Kevin; Paris, Isabelle L.

2004-01-01

Small sub-component specimens consisting of solid laminates at the ends that transition to X-cor(R) truss sandwich in the center, were tested in a combination of three point bending, uni-axial tension, and combined tension and bending. The failure process in the transition region was documented for each loading using digital video and high-resolution cameras. For the 3-point bending tests, most of the deformation occurred in the solid laminate regions on either end of the specimen. Some pin debonding from the skin of the X-cor(R) truss sandwich was observed in the transition region and was accompanied by audible "pings" throughout the loading. Tension loaded specimens failed in the sandwich skin in the middle of the gage length, accompanied by separation of the sandwich core from the back skin and by delamination between the top skin and bottom skin at the transition region. The pinging associated with pin debonding occurred as the load was increased. However, the frequency of the pinging exceeded any visual observations of pin debonding in the video of the transition region. For specimens tested in combined tension and bending, the greatest amount of pinging occurred during initial application of the axial load. High-resolution images in the transition region indicated that the pinging corresponded to pins debonding and buckling due to the through-thickness Poisson contraction of the specimen. This buckling continued to a much smaller extent as the transverse load was applied.

SAMe prevents the induction of the immunoproteasome and preserves the 26S proteasome in the DDC-induced MDB mouse model.

PubMed

Bardag-Gorce, Fawzia; Oliva, Joan; Li, Jun; French, Barbara A; French, Samuel W

2010-06-01

Mallory-Denk bodies (MDBs) form in the liver of alcoholic patients. This occurs because of the accumulation and aggregation of ubiquitinated cytokeratins, which hypothetically is due to the ubiquitin-proteasome pathway's (UPP) failure to degrade the cytokeratins. The experimental model of MDB formation was used in which MDBs were induced by refeeding DDC to drug-primed mice. The gene expression and protein levels of LMP2, LMP7 and MECL-1, the catalytic subunits in the immunoproteasome, as well as FAT10, were increased in the liver cells forming MDBs but not in the intervening normal hepatocytes. Chymotrypsin-like activity of the UPP was decreased by DDC refeeding, indicating that a switch from the UPP to the immunoproteasome had occurred at the expense of the 26S proteasome. The failure of the UPP to digest cytokeratins would explain MDB aggregate formation. SAMe prevented the decrease in UPP activity, the increase in LMP2, LMP7, and MECL-1 protein levels and MDB formation induced by DDC. DDC refeeding also induced the TNFalpha and IFNgamma receptors. SAMe prevented the increase in the TNFalpha and IFNgamma receptors, supporting the idea that TNFalpha and IFNgamma were responsible for the up regulation of LMP2, LPM7, and FAT10. These results support the conclusion that MDBs form in FAT10 over-expressing hepatocytes where the up regulation of the immunoproteasome occurs at the expense of the 26S proteasome. Copyright 2010 Elsevier Inc. All rights reserved.

Air ingression calculations for selected plant transients using MELCOR

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

Kmetyk, L.N.

1994-01-01

Two sets of MELCOR calculations have been completed studying the effects of air ingression on the consequences of various severe accident scenarios. One set of calculations analyzed a station blackout with surge line failure prior to vessel breach, starting from nominal operating conditions; the other set of calculations analyzed a station blackout occurring during shutdown (refueling) conditions. Both sets of analyses were for the Surry plant, a three-loop Westinghouse PWR. For both accident scenarios, a basecase calculation was done, and then repeated with air ingression from containment into the core region following core degradation and vessel failure. In addition tomore » the two sets of analyses done for this program, a similar air-ingression sensitivity study was done as part of a low-power/shutdown PRA, with results summarized here; that PRA study also analyzed a station blackout occurring during shutdown (refueling) conditions, but for the Grand Gulf plant, a BWR/6 with Mark III containment. These studies help quantify the amount of air that would have to enter the core region to have a significant impact on the severe accident scenario, and demonstrate that one effect, of air ingression is substantial enhancement of ruthenium release. These calculations also show that, while the core clad temperatures rise more quickly due to oxidation with air rather than steam, the core also degrades and relocates more quickly, so that no sustained, enhanced core heatup is predicted to occur with air ingression.« less

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.

Simulation Experiment and Acoustic Emission Study on Coal and Gas Outburst

NASA Astrophysics Data System (ADS)

Li, Hui; Feng, Zengchao; Zhao, Dong; Duan, Dong

2017-08-01

A coal and gas outburst is an extreme hazard in underground mining. The present paper conducts a laboratory simulation of a coal and gas outburst combined with acoustic emission analysis. The experiment uses a three-dimensional stress loading system and a PCI-2 acoustic emission monitoring system. Furthermore, the development of a coal and gas outburst is numerically studied. The results demonstrate that the deformation and failure of a coal sample containing methane under three-dimensional stress involves four stages: initial compression, elastic deformation, plastic deformation and failure. The development of internal microscale fractures within a coal sample containing methane is reflected by the distribution of acoustic emission events. We observed that the deformation and failure zone for a coal sample under three-dimensional stress has an ellipsoid shape. Primary acoustic emission events are generated at the weak structural surface that compresses with ease due to the external ellipsoid-shaped stress. The number of events gradually increases until an outburst occurs. A mathematical model of the internal gas pressure and bulk stress is established through an analysis of the internal gas pressure and bulk stress of a coal sample, and it is useful for reproducing experimental results. The occurrence of a coal and gas outburst depends not only on the in situ stress, gas pressure and physical and mechanical characteristics of the coal mass but also on the free weak surface of the outburst outlet of the coal mass. It is more difficult for an outburst to occur from a stronger free surface.

Outcomes of Modified Harrington Reconstructions for Nonprimary Periacetabular Tumors: An Effective and Inexpensive Technique.

PubMed

Bernthal, Nicholas M; Price, Shawn L; Monument, Michael J; Wilkinson, Brandon; Jones, Kevin B; Randall, R Lor

2015-11-01

Metastatic disease to the acetabulum presents a difficult technical and philosophical challenge: complicated surgeries in patients with often short life expectancies force us to examine both the outcome and cost of these operations. Therefore, we studied the durability of a cement-screw rebar reconstruction technique and risk factors for failure, and we compare the results to other reconstruction options. This is a retrospective review of 52 acetabular reconstructions in 50 patients for nonprimary disease using a retrograde screw-rebar-cement all-polyethylene technique. Mean age was 57 years (range 25-81 years). Twenty-four lesions were classified as Harrington class II; 28 were Harrington class III. Mean follow-up was 17.7 months (range 1-92 months). Outcomes included patient survival, prosthesis survival, and complications. Forty-eight of 50 (96 %) patients ambulated after surgery. Five of 52 (9.6 %) of prostheses failed, three from loosening due to tumor progression, one from aseptic loosening, and one from soft tissue instability (dislocation). The three cases of tumor progression failure occurred in patients with massive preoperative ischial tumor burden. Mean surgical time was 198 min, and hospital stay was 5.2 days. The screw-cement-rebar all-polyethylene cup reconstruction technique is a comparatively successful and inexpensive reconstruction option for treating nonprimary oncologic disease in the acetabulum. All cases of loosening occurred beyond the median patient survival. Surgeons should be wary of massive ischial tumor burden in patients with projected longevity, as it may be associated with implant failure. Surgical time and hospital stay are consistent with historical data for alternative implants, and implant cost is lower.

Treatment of renal failure in idiopathic membranous nephropathy with azathioprine and prednisolone.

PubMed

Brown, J H; Douglas, A F; Murphy, B G; Hill, C M; McNamee, P T; Nelson, W E; Doherty, C C

1998-02-01

Progressive deterioration in renal function occurs in 20-50% of patients with idiopathic membranous nephropathy (IMN). Several treatment regimens have been used to reverse this with varying effect and toxicity. Thirteen patients (10 males, 3 females, median age 56 years) with IMN and progressive renal failure were treated with oral prednisolone 20-60 mg/day and azathioprine 1.3-2.7 mg/kgBW/day. All patients were followed up for a minimum of 2 years with a median follow-up of 73 months (range 24-103 months). Ten patients responded to treatment with a fall in serum creatinine and renal function stabilized in the remainder. Two patients relapsed, one of whom responded to an increase in immunosuppression, the other is now on dialysis. Proteinuria has significantly reduced in 10 patients, and only four patients still have nephrotic-range proteinuria. Mean (+/- SE) peak pretreatment serum creatinine of 229 (+/- 161) mumol/l and urinary protein of 11.8 (+/- 1.8) g/24 have fallen to 163 (+/- 65) mumol/l and 3.25 (+/- 1.0) g/24 h after 12 months treatment (P < 0.005, Wilcoxon matched pairs test). Immunosuppressive treatment has been successfully withdrawn in four patients after intervals ranging from 12 to 60 months. Adverse effects, which occurred in 10 patients, have been mild and have not led to treatment withdrawal though dose reductions have been necessary in some patients. Oral prednisolone and low-dose azathioprine is an effective therapy for progressing renal failure due to IMN, and induces remission of nephrotic syndrome. Side-effects are less than other immunosuppressive regimens.

Ventricular assist device implantation in a young patient with non-compaction cardiomyopathy and hereditary spherocytosis.

PubMed

Huenges, Katharina; Panholzer, Bernd; Cremer, Jochen; Haneya, Assad

2018-04-01

A case of a 15-year-old female patient with acute heart failure due to non-compaction cardiomyopathy and hereditary anaemia (hereditary spherocytic elliptocytosis) requiring ventricular assist device implantation as a bridge to transplantation is presented. The possible effects of mechanical stress on erythrocytes potentially induced by mechanical circulatory support remains unclear, but it may lead to haemolytic crisis in patients suffering from hereditary anaemia. In our case, ventricular assist device therapy was feasible, and haematological complications did not occur within 6 weeks of bridging our patient to heart transplantation.

Ion beam sputter-etched ventricular catheter for hydrocephalus shunt

NASA Technical Reports Server (NTRS)

Banks, B. A. (Inventor)

1983-01-01

A cerebrospinal fluid shunt in the form of a ventricular catheter for controlling the condition of hydrocephalus by relieving the excessive cerebrospinal fluid pressure is described. A method for fabrication of the catheter and shunting the cerebral fluid from the cerebral ventricles to other areas of the body is also considered. Shunt flow failure occurs if the ventricle collapse due to improper valve function causing overdrainage. The ventricular catheter comprises a multiplicity of inlet microtubules. Each microtubule has both a large openings at its inlet end and a multiplicity of microscopic openings along its lateral surfaces.

Early detection of congenital syphilis.

PubMed

Chowdhary, Nagalakshmi; Rani, Bs Kavya; Mukunda, K S; Kiran, N K

2014-01-01

Late congenital syphilis is a very rare clinical entity, and its early diagnosis and treatment is essential. Dental findings often provide valuable evidence for the diagnosis of late congenital syphilis. It occurs due to the transmission of the disease from an infected mother to her fetus through placenta. This long forgotten disease continues to effect pregnant women resulting in perinatal morbidity and mortality. Congenital syphilis is a preventable disease, and its presence reflects a failure of prenatal care delivery system, as well as syphilis control programs. We are reporting a case of late congenital syphilis with only Hutchinson's teeth.

Acute Sheehan's syndrome presenting as central diabetes insipidus.

PubMed

Robalo, Raquel; Pedroso, Célia; Agapito, Ana; Borges, Augusta

2012-11-06

Sheehan's syndrome occurs as a result of ischaemic pituitary necrosis due to severe postpartum haemorrhage. Improvements in obstetrical care have significantly reduced its incidence in developed countries, but postpartum pituitary infarction remains a common cause of hypopituitarism in developing countries. We report a case of severe postpartum haemorrhage followed by headache, central diabetes insipidus and failure to lactate, which prompted us to investigate and identify both anterior and posterior pituitary deficiency compatible with Sheehan's syndrome. A timely diagnosis allowed us to implement an adequate treatment and follow-up plan, which are known to improve clinical status and patient outcome.

Management of Coronary Sinus Ostial Atresia during a Staged Operation of a Functional Single Ventricle.

PubMed

Kang, Seung Ri; Park, Won Kyoun; Kwon, Bo Sang; Ko, Jae Kon; Goo, Hyun Woo; Park, Jeong-Jun

2018-04-01

Coronary sinus ostial atresia (CSOA) with persistent left superior vena cava (LSVC) in the absence of an unroofed coronary sinus is a benign and rare anomaly that may be taken lightly in most instances. However, if overlooked in patients undergoing univentricular heart repair such as bidirectional Glenn or Fontan-type surgery, fatal surgical outcomes may occur due to coronary venous drainage failure. We report a case of CSOA with a persistent LSVC that was managed through coronary sinus rerouting during a total cavopulmonary connection, and provide a review of the literature regarding this rare anomaly.

Paralysis Episodes in Carbonic Anhydrase II Deficiency.

PubMed

Al-Ibrahim, Alia; Al-Harbi, Mosa; Al-Musallam, Sulaiman

2003-01-01

Carbonic anhydrase II (CAII) deficiency is an autosomal recessive disorder manifest by osteopetrosis, renal tubular acidosis, and cerebral calcification. Other features include growth failure and mental retardation. Complications of the osteopetrosis include frequent bone fractures, cranial nerve compression, and dental mal-occlusion. A hyper-chloremic metabolic acidosis, sometimes with hypokalemia, occurs due to renal tubular acidosis that may be proximal, distal, or more commonly, the combined type. Such patients may present with global hypotonia, muscle weakness or paralysis. We report a case of CA II deficiency with recurrent attacks of acute paralysis which was misdiagnosed initially as Guillian-Barre syndrome.

History of significant earthquakes in the Parkfield area

USGS Publications Warehouse

Bakun, W.H.

1988-01-01

Seismicity on the San Andreas fault near Parkfield occurs in a tectonic section that differs markedly from neighboring sections along the San Andreas to the northwest and to the southeast. Northwest of the Parkfield section, small shocks (magnitudes of less than 4) do occur frequently, but San Andreas movement occurs predominantly as aseismic fault creep; shocks of magnitude 6 and larger are unknown, and little, if any, strain is accumulating. In contrast, very few small earthquakes and no aseismic slip have been observed on the adjacent section to the southeast, the Cholame section, which is considered to be locked, in as much as it apparently ruptures exclusively in large earthquakes (magnitudes greater than 7), most recently during the great Fort Tejon earthquake of 1857. The Parkfield section is thus a transition zone between two sections having different modes of fault failure. In fact, the regularity of significant earthquakes at Parkfield since 1857 may be due to the nearly constant slip rate pattern on the adjoining fault sections. Until the magnitude 6.7 Coalinga earthquake on May 2, 1983, 40 kilmoeters northeast of Parkfield, the Parkfield section had been relatively free of stress changes due to nearby shocks; the effect of the Coalinga shock on the timing of the next Parkfield shock is not known. 

[Percutaneous stented pulmonary valve implantation].

PubMed

Ersbøll, Mads; Søndergaard, Lars

2010-03-29

A number of congenital cardiac malformations involve the right ventricular outflow tract and are often treated with a biological valved conduit. The longevity of these valves is limited due to graft degeneration, which causes progressive valvular dysfunction and subsequently right ventricular failure. Due to the young age of these patients, repeat surgery can be expected and this has motivated the invention of the percutaneous stented valve implantation (PPVR). We retrospectively examined 13 patients (mean age 26 +/- 10 years) treated with PPVR between 2006 and 2008 at our institution. Indications for PPVR were conduit dysfunction with severe stenosis and/or regurgitation, reduced exercise capacity and right ventricular dilatation. In all patients, immediate haemodynamic improvement occurred with full valvular competence after PPVR. The pressure gradient was reduced from 43 (+/- 15) mmHg to 12 (+/- 7) mmHg (p = 0,05) in patients with combined regurgitation and stenosis and 47 (+/- 14) mmHg to 12 (+/- 2) mmHg (p = 0,05) in patients with isolated stenosis. At mean follow-up after 141 (+/- 140) days, no reintervention had been required. Significant haemodynamic and clinical improvement occurred after PPVR in all patients and no major complications occurred. PPVR remains a safe and minimally invasive treatment modality, and our study demonstrates that PPVR can be safely performed in a low volume setting.

Why Lumbar Artificial Disk Replacements (LADRs) Fail.

PubMed

Pettine, Kenneth; Ryu, Robert; Techy, Fernando

2017-07-01

A retrospective review of prospectively collected data. To determine why artificial disk replacements (ADRs) fail by examining results of 91 patients in FDA studies performed at a single investigational device exemption (IDE) site with minimum 2-year follow-up. Patients following lumbar ADR generally achieve their 24-month follow-up results at 3 months postoperatively. Every patient undergoing ADR at 1 IDE site by 2 surgeons was evaluated for clinical success. Failure was defined as <50% improvement in ODI and VAS or any additional surgery at index or adjacent spine motion segment. Three ADRs were evaluated: Maverick, 25 patients; Charité, 31 patients; and Kineflex, 35 patients. All procedures were 1-level operations performed at L4-L5 or L5-S1. Demographics and inclusion/exclusion criteria were similar and will be discussed. Overall clinical failure occurred in 26% (24 of 91 patients) at 2-year follow-up. Clinical failure occurred in: 28% (Maverick) (7 of 25 patients), 39% (Charité) (12 of 31 patients), and 14% (Kineflex) (5 of 35 patients). Causes of failure included facet pathology, 50% of failure patients (12 of 24). Implant complications occurred in 5% of total patients and 21% of failure patients (5 of 24). Only 5 patients went from a success to failure after 3 months. Only 1 patient went from a failure to success after a facet rhizotomy 1 year after ADR. Seventy-four percent of patients after ADR met strict clinical success after 2-year follow-up. The clinical success versus failure rate did not change from their 3-month follow-up in 85 of the 91 patients (93%). Overall clinical success may be improved most by patient selection and implant type.

Postbuckling failure of composite plates with central holes. Interim Report, Feb. 1990 - Dec. 1991 Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Lee, H. H.; Hyer, M. W.

1992-01-01

The postbuckling failure of square composite plates with central holes is analyzed numerically and experimentally. The particular plates studies have stacking sequences of: (+ and - 45/0/90)(sub 2S); (+ and - 45/0(sub 2))(sub 2S); (+ and - 45/0(sub 6))(sub S); and (+ and - 45)(sub 4S). A simple plate geometry, one with a hole diameter to plate width ratio of 0.3 is compared. Failure load, failure mode, and failure location are predicted numerically by using the finite element method. Predictions are compared with experimental results. In numerical failure analysis the interlaminar shear stresses, as well as the inplane stresses are taken into account. An issue addressed in this study is the possible mode shape change of the plate during loading. It is predicted that the first three laminates fail due to excessive stresses in the fiber direction, and more importantly, that the load level is independent of whether the laminate is deformed in a one-half or two-half wave configuration. It is predicted that the fourth laminate fails due to excessive inplane shear stress. Interlaminar shear failure is not predicted for any laminates. For the first two laminates the experimental observations correlated well with the predictions. Experimentally, the third laminate failed along the side support due to interlaminar shear strength S(sub 23). The fourth experimental laminate failed due to inplane shear in the location predicted, however material softening resulted in a different failure load from predictions.

Acute-on-Chronic Liver Failure: Getting ready for prime-time.

PubMed

Bajaj, Jasmohan S; Moreau, Richard; Kamath, Patrick S; Vargas, Hugo E; Arroyo, Vicente; Reddy, K Rajender; Szabo, Gyongyi; Tandon, Puneeta; Olson, Jody; Karvellas, Constantine; Gustot, Thierry; Lai, Jennifer C; Wong, Florence

2018-04-24

Acute on chronic liver failure (ACLF) is a culmination of chronic liver disease and extra-hepatic organ failures, which is associated with a high short-term mortality and immense healthcare expenditure. There are varying definitions for organ failures and ACLF in Europe, North America and Asia. These differing definitions need to be reconciled to enhance progress in the field. The pathogenesis of ACLF is multi-factorial and related to interactions between the immuno-inflammatory system, microbiota and the precipitating factors. Individual organ failures related to the kidney, brain, lungs and circulation have cumulative adverse effects on mortality and are often complicated or precipitated by infections. Strategies to prevent and rapidly treat these organ failures are paramount in improving survival. With the aging population and paucity of organs for liver transplant, the prognosis of ACLF patients is poor, highlighting the need for novel therapeutic strategies. The role of liver transplant in ACLF is evolving and needs further investigation across large consortia. A role for early palliative care and management of frailty as approaches to alleviate disease burden and improve patient-reported outcomes is being increasingly recognized. ACLF is a clinically relevant syndrome that is epidemic worldwide and which requires a dedicated multi-national approach focused on prognostication and management. Investigations are underway worldwide to get ACLF ready for prime time. Compensated cirrhosis with >90% 1-year survival can transition into the decompensated stage with the onset of jaundice, ascites, variceal bleeding and hepatic encephalopathy (HE) (1)Acute on chronic liver failure (ACLF) is associated with rapid deterioration of liver function leading to liver failure, multiple extra-hepatic organ failures and high short-term mortality (2). Even if patients survive the acute insult, they may never return to their pre-episode functional state (3). The term "acute decompensation" has been used to characterize ascites, gastrointestinal bleeding, hepatic encephalopathy or infections without organ failure(4). There are several gaps in knowledge surrounding ACLF, which will be highlighted in this review. The prevalence of ACLF is difficult to assess due to varying regional definitions (5). ACLF, once thought to occur only in decompensated cirrhosis, has been recognized even in chronic liver disease without cirrhosis (5). ACLF occurs in approximately 10-30% of hospitalized cirrhotic patients (6-8). Because of its acuity, patients are frequently admitted into the intensive care unit (ICU), and every effort is made to stabilize these patients for liver transplantation (LT). This drives healthcare costs(9). Despite this intensive management, ACLF is associated with substantial morbidity and mortality. Because curative LT is only available to <10% of cirrhotic patients each year and ACLF patients are often delisted, the morbidity and mortality rates remain high, especially with an increasing number of organ failures (10). This article is protected by copyright. All rights reserved. © 2018 by the American Association for the Study of Liver Diseases.

Early childhood growth failure and the developmental origins of adult disease: Do enteric infections and malnutrition increase risk for the metabolic syndrome?

PubMed Central

DeBoer, Mark D.; Lima, Aldo A. M.; Oría, Reinaldo B.; Scharf, Rebecca J.; Moore, Sean R.; Luna, Max A.; Guerrant, Richard L.

2012-01-01

Hypotheses regarding the developmental origins of health and disease postulate that developing fetuses–and potentially young children—undergo adaptive epigenetic changes with longstanding effects on metabolism and other processes. Ongoing research explores whether these adaptations occur during early life following malnutrition. In the developing world there remains a high degree of nutritional stunting—linear growth failure due to inadequate calories that may be exacerbated by inflammation from ongoing infections. In areas with poor sanitation children experience vicious cycles of enteric infections and malnutrition, resulting in poor nutrient absorption from intestinal mucosa changes now termed “environmental enteropathy.” Emerging evidence links early childhood diarrhea and/or growth failure with increased CVD risk factors in later life, including dyslipidemia, hypertension and glucose intolerance. The mechanisms for these associations remain poorly understood and may relate to epigenetic responses to poor nutrition, increased inflammation or both. Given increases in CVD in developing areas of the world, associations between childhood malnutrition, early life infections and increased CVD risk factors underscore further reasons to improve nutrition and infection-related outcomes for young children worldwide. PMID:23110643

Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/Epoxy Tows and Implications for Composite Structures

NASA Technical Reports Server (NTRS)

Waller, Jess M.; Saulsberry, Regor L.; Nichols, Charles T.; Wentzel, Daniel J.

2010-01-01

This slide presentation reviews the use of Modal Acoustic Emission to monitor damage progression to carbon fiber/epoxy tows. There is a risk for catastrophic failure of composite overwrapped pressure vessels (COPVs) due to burst-before-leak (BBL) stress rupture (SR) failure of carbon-epoxy (C/Ep) COPVs. A lack of quantitative nondestructive evaluation (NDE) is causing problems in current and future spacecraft designs. It is therefore important to develop and demonstrate critical NDE that can be implemented during stages of the design process since the observed rupture can occur with little of no advanced warning. Therefore a program was required to develop quantitative acoustic emission (AE) procedures specific to C/Ep overwraps, but which also have utility for monitoring damage accumulation in composite structure in general, and to lay the groundwork for establishing critical thresholds for accumulated damage in composite structures, such as COPVs, so that precautionary or preemptive engineering steps can be implemented to minimize of obviate the risk of catastrophic failure. A computed Felicity Ratio (FR) coupled with fast Fourier Transform (FFT) frequency analysis shows promise as an analytical pass/fail criterion. The FR analysis and waveform and FFT analysis are reviewed

rpsftm: An R Package for Rank Preserving Structural Failure Time Models

PubMed Central

Allison, Annabel; White, Ian R; Bond, Simon

2018-01-01

Treatment switching in a randomised controlled trial occurs when participants change from their randomised treatment to the other trial treatment during the study. Failure to account for treatment switching in the analysis (i.e. by performing a standard intention-to-treat analysis) can lead to biased estimates of treatment efficacy. The rank preserving structural failure time model (RPSFTM) is a method used to adjust for treatment switching in trials with survival outcomes. The RPSFTM is due to Robins and Tsiatis (1991) and has been developed by White et al. (1997, 1999). The method is randomisation based and uses only the randomised treatment group, observed event times, and treatment history in order to estimate a causal treatment effect. The treatment effect, ψ, is estimated by balancing counter-factual event times (that would be observed if no treatment were received) between treatment groups. G-estimation is used to find the value of ψ such that a test statistic Z(ψ) = 0. This is usually the test statistic used in the intention-to-treat analysis, for example, the log rank test statistic. We present an R package that implements the method of rpsftm. PMID:29564164

rpsftm: An R Package for Rank Preserving Structural Failure Time Models.

PubMed

Allison, Annabel; White, Ian R; Bond, Simon

2017-12-04

Treatment switching in a randomised controlled trial occurs when participants change from their randomised treatment to the other trial treatment during the study. Failure to account for treatment switching in the analysis (i.e. by performing a standard intention-to-treat analysis) can lead to biased estimates of treatment efficacy. The rank preserving structural failure time model (RPSFTM) is a method used to adjust for treatment switching in trials with survival outcomes. The RPSFTM is due to Robins and Tsiatis (1991) and has been developed by White et al. (1997, 1999). The method is randomisation based and uses only the randomised treatment group, observed event times, and treatment history in order to estimate a causal treatment effect. The treatment effect, ψ , is estimated by balancing counter-factual event times (that would be observed if no treatment were received) between treatment groups. G-estimation is used to find the value of ψ such that a test statistic Z ( ψ ) = 0. This is usually the test statistic used in the intention-to-treat analysis, for example, the log rank test statistic. We present an R package that implements the method of rpsftm.

Detecting Solenoid Valve Deterioration in In-Use Electronic Diesel Fuel Injection Control Systems

PubMed Central

Tsai, Hsun-Heng; Tseng, Chyuan-Yow

2010-01-01

The diesel engine is the main power source for most agricultural vehicles. The control of diesel engine emissions is an important global issue. Fuel injection control systems directly affect fuel efficiency and emissions of diesel engines. Deterioration faults, such as rack deformation, solenoid valve failure, and rack-travel sensor malfunction, are possibly in the fuel injection module of electronic diesel control (EDC) systems. Among these faults, solenoid valve failure is most likely to occur for in-use diesel engines. According to the previous studies, this failure is a result of the wear of the plunger and sleeve, based on a long period of usage, lubricant degradation, or engine overheating. Due to the difficulty in identifying solenoid valve deterioration, this study focuses on developing a sensor identification algorithm that can clearly classify the usability of the solenoid valve, without disassembling the fuel pump of an EDC system for in-use agricultural vehicles. A diagnostic algorithm is proposed, including a feedback controller, a parameter identifier, a linear variable differential transformer (LVDT) sensor, and a neural network classifier. Experimental results show that the proposed algorithm can accurately identify the usability of solenoid valves. PMID:22163597

Hepatitis C virus resistance to the new direct-acting antivirals.

PubMed

Esposito, Isabella; Trinks, Julieta; Soriano, Vicente

2016-10-01

The treatment of hepatitis C virus (HCV) infection has dramatically improved in recent years with the widespread use of interferon-free combination regimens. Despite the high sustained virological response (SVR) rates (over 90%) obtained with direct-acting antivirals (DAAs), drug resistance has emerged as a potential challenge. The high replication rate of HCV and the low fidelity of its RNA polymerase result in a high degree of genetic variability in the HCV population, which ultimately explains the rapid selection of drug resistance associated variants (RAVs). Results from clinical trials and real-world experience have both provided important information on the rate and clinical significance of RAVs. They can be present in treatment-naive patients as natural polymorphisms although more frequently they are selected upon treatment failure. In patients engaged in high-risk behaviors, RAVs can be transmitted. Although DAA failures generally occur in less than 10% of treated chronic hepatitis C patients, selection of drug resistance is the rule in most cases. HCV re-treatment options are available, but first-line therapeutic strategies should be optimized to efficiently prevent DAA failure due to baseline HCV resistance. Considerable progress is being made and next-generation DAAs are coming with pangenotypic activity and higher resistance barrier.

Detecting solenoid valve deterioration in in-use electronic diesel fuel injection control systems.

PubMed

Tsai, Hsun-Heng; Tseng, Chyuan-Yow

2010-01-01

The diesel engine is the main power source for most agricultural vehicles. The control of diesel engine emissions is an important global issue. Fuel injection control systems directly affect fuel efficiency and emissions of diesel engines. Deterioration faults, such as rack deformation, solenoid valve failure, and rack-travel sensor malfunction, are possibly in the fuel injection module of electronic diesel control (EDC) systems. Among these faults, solenoid valve failure is most likely to occur for in-use diesel engines. According to the previous studies, this failure is a result of the wear of the plunger and sleeve, based on a long period of usage, lubricant degradation, or engine overheating. Due to the difficulty in identifying solenoid valve deterioration, this study focuses on developing a sensor identification algorithm that can clearly classify the usability of the solenoid valve, without disassembling the fuel pump of an EDC system for in-use agricultural vehicles. A diagnostic algorithm is proposed, including a feedback controller, a parameter identifier, a linear variable differential transformer (LVDT) sensor, and a neural network classifier. Experimental results show that the proposed algorithm can accurately identify the usability of solenoid valves.

Strength criteria for composite materials (a literature survey)

NASA Technical Reports Server (NTRS)

Roode, F.

1982-01-01

Literature concerning strength (failure) criteria for composite materials is reviewed with emphasis on phenomenological failure criteria. These criteria are primarily intended to give a good estimation of the safety margin with respect to failure for arbitrary multiaxial stress states. The failure criteria do not indicate the types of fracture that will occur in the material. The collection of failure criteria is evaluated for applicability for the glass reinforced plastics used in mine detectors. Material tests necessary to determine the parameters in the failure criteria are discussed.

Pulmonary hypertension and predominant right heart failure in thyrotoxicosis.

PubMed

Paran, Yael; Nimrod, Adi; Goldin, Yelena; Justo, Dan

2006-05-01

In this report we discuss a patient with predominant right heart failure and pulmonary hypertension, caused by thyrotoxicosis due to Graves disease, which deteriorated to asystole, due to amiodarone administration for rapid atrial fibrillation.

How much of a problem is resistance in treating hepatitis C?

PubMed

Forton, Daniel M

2016-12-01

Directly acting antiviral drug (DAA) treatments represent a major advance in hepatitis C management, achieving virological cures in excess of 90%. When treatment failure occurs, it is mostly due to relapse with the emergence of resistance-associated variants. Data from in-vitro studies and clinical trials have enabled characterization of the amino acid substitutions in antiviral drug targets that confer reduced susceptibility to DAAs. These resistance-associated substitutions (RASs) may exist prior to treatment, and are associated with, but do not inevitably result in, treatment failure. The most important RASs with current regimens occur in the NS5A protein of viral variants, which may persist for years after treatment. The optimal strategy is to prevent resistance through administering the best treatment, appropriately matched to patient and virological characteristics, for example the presence of cirrhosis, prior exposure to interferon and so on. International treatment guidelines have been developed to select treatments, which may vary in duration and coadministration with ribavirin. Routine resistance testing prior to treatment of naive patients is not generally recommended. Next-generation DAAs will further reduce the emergence of RASs and, because of activity against RASs to currently used DAAs, will be used as rescue therapies for patients who have failed treatment.

Anterior longitudinal ligament injuries in whiplash may lead to cervical instability.

PubMed

Stemper, Brian D; Yoganandan, Narayan; Pintar, Frank A; Rao, Raj D

2006-07-01

Although whiplash injuries account for a significant annual cost to society, the exact mechanism of injury and affected tissues remain unknown. Previous investigations documented injuries to the cervical anterior longitudinal ligament in whiplash. The present investigation implemented a comprehensively validated computational model to quantify level-dependent distraction magnitudes of this structure in whiplash. Maximum ligament distractions approached failure levels, particularly in middle to lower cervical levels, and occurred during the initial phase of head-neck kinematics. In particular, the C5-C6 anterior longitudinal ligament sustained distraction magnitudes as high as 2.6mm during the retraction phase, corresponding to 56% of distraction necessary to result in ligament failure. Present results demonstrated that anterior structures in the lower cervical spine may be susceptible to injury through excess distraction during the retraction phase of whiplash, which likely occurs prior to head restraint contact. Susceptibility of these structures is likely due to non-physiologic loading placed on the cervical spinal column as the head translates posteriorly relative to the thorax. Injury to anterior spinal structures can result in clinical indications including cervical instability in extension, axial rotation, and lateral bending modes. Mitigation of whiplash injury may be achieved by minimizing head retraction during initial stages of whiplash.

Sparse reconstruction localization of multiple acoustic emissions in large diameter pipelines

NASA Astrophysics Data System (ADS)

Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

2017-04-01

A sparse reconstruction localization method is proposed, which is capable of localizing multiple acoustic emission events occurring closely in time. The events may be due to a number of sources, such as the growth of corrosion patches or cracks. Such acoustic emissions may yield localization failure if a triangulation method is used. The proposed method is implemented both theoretically and experimentally on large diameter thin-walled pipes. Experimental examples are presented, which demonstrate the failure of a triangulation method when multiple sources are present in this structure, while highlighting the capabilities of the proposed method. The examples are generated from experimental data of simulated acoustic emission events. The data corresponds to helical guided ultrasonic waves generated in a 3 m long large diameter pipe by pencil lead breaks on its outer surface. Acoustic emission waveforms are recorded by six sparsely distributed low-profile piezoelectric transducers instrumented on the outer surface of the pipe. The same array of transducers is used for both the proposed and the triangulation method. It is demonstrated that the proposed method is able to localize multiple events occurring closely in time. Furthermore, the matching pursuit algorithm and the basis pursuit densoising approach are each evaluated as potential numerical tools in the proposed sparse reconstruction method.

Respiratory failure presenting in H1N1 influenza with Legionnaires disease: two case reports

PubMed Central

2011-01-01

Introduction Media sensationalism on the H1N1 outbreak may have influenced decisional processes and clinical diagnosis. Case Presentation We report two cases of patients who presented in 2009 with coexisting H1N1 virus and Legionella infections: a 69-year-old Caucasian man and a 71-year-old Caucasian woman. In our cases all the signs and symptoms, including vomiting, progressive respiratory disease leading to respiratory failure, refractory hypoxemia, leukopenia, lymphopenia, thrombocytopenia, and elevated levels of creatine kinase and hepatic aminotransferases, were consistent with critical illness due to 2009 H1N1 virus infection. Other infectious disorders may mimic H1N1 viral infection especially Legionnaires' disease. Because the swine flu H1N1 pandemic occurred in Autumn in Italy, Legionnaires disease was to be highly suspected since the peak incidence usually occurs in early fall. We do think that our immediate suspicion of Legionella infection based on clinical history and X-ray abnormalities was fundamental for a successful resolution. Conclusion Our two case reports suggest that patients with H1N1 should be screened for Legionella, which is not currently common practice. This is particularly important since the signs and symptoms of both infections are similar. PMID:22018019

Forward Skirt Structural Testing on the Space Launch System (SLS) Program

NASA Technical Reports Server (NTRS)

Lohrer, J. D.; Wright, R. D.

2016-01-01

Structural testing was performed to evaluate heritage forward skirts from the Space Shuttle program for use on the Space Launch System (SLS) program. One forward skirt is located in each solid rocket booster. Heritage forward skirts are aluminum 2219 welded structures. Loads are applied at the forward skirt thrust post and ball assembly. Testing was needed because SLS ascent loads are roughly 40% higher than Space Shuttle loads. Testing objectives were to determine margins of safety, demonstrate reliability, and validate analytical models. Two forward skirts were structurally tested using the test configuration. The test stand applied loads to the thrust post. Four hydraulic actuators were used to apply axial load and two hydraulic actuators were used to apply radial and tangential loads. The first test was referred to as FSTA-1 (Forward Skirt Structural Test Article) and was performed in April/May 2014. The purpose of FSTA-1 was to verify the ultimate capability of the forward skirt subjected to ascent ultimate loads. Testing consisted of two liftoff load cases taken to 100% limit load followed by an ascent load case taken to 110% limit load. The forward skirt was unloaded to no load after each test case. Lastly, the forward skirt was tested to 140% limit and then to failure using the ascent loads. The second test was referred to as FSTA-2 and performed in July/August of 2014. The purpose of FSTA-2 was to verify the ultimate capability of the forward skirt subjected to liftoff ultimate loads. Testing consisted of six liftoff load cases taken to 100% limit load followed by the six liftoff cases taken to 140% limit load. Two ascent load cases were then tested to 100% limit load. The forward skirt was unloaded to no load after each test case. Lastly, the forward skirt was tested to 140% limit and then to failure using the ascent loads. The forward skirts on FSTA-1 and FSTA-2 successfully carried all applied liftoff and ascent load cases. Both FSTA-1 and FSTA-2 were tested to failure by increasing the ascent loads. Failure occurred in the forward skirt thrust post radius. The forward skirts on FSTA-1 and FSTA-2 had nearly identical failure modes. FSTA-1 failed at 1.72 times limit load and FSTA-2 failed at 1.62 times limit load. This difference is primarily attributed to variation in material properties in the thrust post region. Test data were obtained from strain gages, deflection gages, ARAMIS digital strain measurement, acoustic emissions, and high-speed video. Strain gage data and ARAMIS strain were compared to finite element (FE) analysis predictions. Both the forward skirt and tooling were modeled. This allows the analysis to simulate the loading as close as possible to actual test configuration. FSTA-1 and FSTA-2 were instrumented with over 200 strain gages to ensure all possible failure modes could be captured. However, it turned out that three gages provided critical strain data. One was located in the post bore and two on the post radius. More gages were not specified due to space limitations and the desire to not interfere with the use of the ARAMIS system on the post radius. Measured strains were compared to analysis results for the load cycle to failure. Note that FSTA-1 gages were lost before failure was reached. FSTA-2 gages made it to the failure load but one of the radius gages was lost before testing began. This gage was not replaced because of the time and cost associated with disassembly of the test structure. Correlation to analysis was excellent for FSTA-1. FSTA-2 was not quite as good because there was more residual strain from previous load cycles. FSTA-2 was loaded and unloaded with 12 liftoff cases and two ascent cases before taking the skirt to failure. FSTA-1 only had two liftoff cases and one ascent case before taking the skirt to failure. The ARAMIS system was used to determine strain at the post radius by processing digital images of a speckled paint pattern. Digital cameras recorded images of the speckled paint pattern. ARAMIS strain results for FSTA-2 just prior to failure. Note a high strain location develops near the left side. This high strain compares well to analysis prediction for both FSTA-1 and FSTA-2. The strain at this location was also plotted versus limit load. Both FSTA-1 and FSTA-2 had excellent correlation between ARAMIS and analysis strains. Acoustic emission (AE) sensors were used to monitor for damage formation that may occur during testing (e.g., crack formation and growth or propagation). AE was very important because after disassembly of FSTA-1, a crack was observed in the ball fitting radius. The ball fitting did not crack on FSTA-2. AE data was used to reconstruct when the crack occurred. The AE energy versus time plot for FSTA. The energy increased considerably at 850 seconds (152% limit load), indicating a crack could have formed at this point. The only visual evidence found that could have corresponded to this was the crack that initiated in the ball fitting. The cracks in the forward skirt aluminum structures would likely have been lower energy due to a lower modulus and all that were found after failure correlated to occurring after the initial crack in the post radius. This was verified by high-speed cameras used to record the failure.

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.

Co-occurring anxiety influences patterns of brain activity in depression.

PubMed

Engels, Anna S; Heller, Wendy; Spielberg, Jeffrey M; Warren, Stacie L; Sutton, Bradley P; Banich, Marie T; Miller, Gregory A

2010-03-01

Brain activation associated with anhedonic depression and co-occurring anxious arousal and anxious apprehension was measured by fMRI during performance of an emotion word Stroop task. Consistent with EEG findings, depression was associated with rightward frontal lateralization in the dorsolateral prefrontal cortex (DLPFC), but only when anxious arousal was elevated and anxious apprehension was low. Activity in the right inferior frontal gyrus (IFG) was also reduced for depression under the same conditions. In contrast, depression was associated with more activity in the anterior cingulate cortex (dorsal ACC and rostral ACC) and the bilateral amygdala. Results imply that depression, particularly when accompanied by anxious arousal, may result in a failure to implement top-down processing by appropriate brain regions (left DLPFC, right IFG) due to increased activation in regions associated with responding to emotionally salient information (right DLPFC, amygdala).

Co-occurring Anxiety Influences Patterns of Brain Activity in Depression

PubMed Central

Engels, Anna S.; Heller, Wendy; Spielberg, Jeffrey M.; Warren, Stacie L.; Sutton, Bradley P.; Banich, Marie T.; Miller, Gregory A.

2011-01-01

Brain activation associated with anhedonic depression and co-occurring anxious arousal and anxious apprehension was measured by fMRI during performance of an emotion-word Stroop task. Consistent with EEG findings, depression was associated with rightward frontal lateralization in dorsolateral prefrontal cortex (DLPFC), but only when anxious arousal was elevated and anxious apprehension was low. Activity in right inferior frontal gyrus (IFG) was also reduced for depression under the same conditions. In contrast, depression was associated with more activity in anterior cingulate cortex (dACC and rACC) and bilateral amygdala. Results imply that depression, particularly when accompanied by anxious arousal, may result in a failure to implement top-down processing by appropriate brain regions (left DLPFC, right IFG) due to increased activation in regions associated with responding to emotionally salient information (right DLPFC, amygdala). PMID:20233962

Results from extrapleural clipping of a patent ductus arteriosus in seriously ill preterm infants.

PubMed

Demirturk, Orhan; Güvener, Murat; Coşkun, Isa; Tünel, Hüseyin Ali

2011-12-01

Minithoracotomy for extrapleural closure of the patent ductus arteriosus (PDA) in seriously ill patients offers a fast and less invasive alternative to conventional transpleural ductal closure. This study reports the immediate postoperative clinical outcomes for 24 extrapleurally clipped premature infants presenting with congestive heart failure in high-risk comorbidity status between March 2007 and November 2010. The demographics, preoperative clinical characteristics, and postoperative outcomes of the patients, including echocardiographic assessments, were evaluated. No surgery-related mortalities occurred. Four mortalities occurred after surgery due to sepsis and bleeding diathesis. All 20 surviving patients exhibited normal left ventricular dimensions and systolic function in the immediate follow-up period. The study shows that extrapleural clip closure in seriously ill premature infants has an acceptable overall short-term mortality and complication rate with a high rate of ductal closure.

STS-51 pad abort. OV103-engine 2033 (ME-2) fuel flowmeter sensor open circuit

NASA Technical Reports Server (NTRS)

1993-01-01

The STS-51 initial launch attempt of Discovery (OV-103) was terminated on KSC launch pad 39B on 12 Aug. 1993 at 9:12 AM E.S.T. due to a sensor redundancy failure in the liquid hydrogen system of ME-2 (Engine 2033). The event description and time line are summarized. Propellant loading was initiated on 12 Aug. 1993 at 12:00 AM EST. All space shuttle main engine (SSME) chill parameters and Launch Commit Criteria (LCC) were nominal. At engine start plus 1.34 seconds a Failure Identification (FID) was posted against Engine 2033 for exceeding the 1800 spin intra-channel (A1-A2) Fuel Flowrate sensor channel qualification limit. The engine was shut down at 1.50 seconds followed by Engines 2032 and 2030. All shut down sequences were nominal and the mission was safely aborted. SSME Avionics hardware and software performed nominally during the incident. A review of vehicle data table (VDT) data and controller software logic revealed no failure indications other than the single FID 111-101, Fuel Flowrate Intra-Channel Test Channel A disqualification. Software logic was executed according to requirements and there was no anomalous controller software operation. Immediately following the abort, a Rocketdyne/NASA failure investigation team was assembled. The team successfully isolated the failure cause to an open circuit in a Fuel Flowrate Sensor. This type of failure has occurred eight previous times in ground testing. The sensor had performed acceptably on three previous flights of the engine and SSME flight history shows 684 combined fuel flow rate sensor channel flights without failure. The disqualification of an Engine 2 (SSME No. 2033) Fuel Flowrate sensor channel was a result of an instrumentation failure and not engine performance. All other engine operations were nominal. This disqualification resulted in an engine shutdown and safe sequential shutdown of all three engines prior to ignition of the solid boosters.

Effectiveness of infliximab after adalimumab failure in Crohn's disease.

PubMed

Chaparro, María; Andreu, Montserrat; Barreiro-de Acosta, Manuel; García-Planella, Esther; Ricart, Elena; Domènech, Eugeni; Esteve, María; Merino, Olga; Nos, Pilar; Peñalva, Mireia; Gisbert, Javier P

2012-10-07

To evaluate the effectiveness of infliximab as a second-line therapy in Crohn's disease patients after adalimumab failure. A historical cohort study in a community-based gastroenterology practice evaluated Crohn's disease patients treated with infliximab (induction plus maintenance) after adalimumab failure. Patients were identified using a large Spanish database (ENEIDA). We included 15 Crohn's disease patients who received infliximab after adalimumab failure. Five patients discontinued adalimumab due to loss of response, 3 due to adverse events and 7 due to partial response. After infliximab therapy was started, all patients who had interrupted adalimumab due to loss of efficacy regained response. All patients who discontinued adalimumab due to adverse events responded to infliximab and maintained this response; one of these patients had an uneventful course on infliximab, but 2 developed adverse events. None of the 7 patients who interrupted adalimumab due to partial response reached remission with infliximab. Switching from adalimumab to infliximab may be useful in patients who develop adverse effects or loss of response, however, the benefit of infliximab in primary nonresponders was not established.

Effectiveness of infliximab after adalimumab failure in Crohn's disease

PubMed Central

Chaparro, María; Andreu, Montserrat; Barreiro-de Acosta, Manuel; García-Planella, Esther; Ricart, Elena; Domènech, Eugeni; Esteve, María; Merino, Olga; Nos, Pilar; Peñalva, Mireia; Gisbert, Javier P

2012-01-01

AIM: To evaluate the effectiveness of infliximab as a second-line therapy in Crohn’s disease patients after adalimumab failure. METHODS: A historical cohort study in a community-based gastroenterology practice evaluated Crohn’s disease patients treated with infliximab (induction plus maintenance) after adalimumab failure. Patients were identified using a large Spanish database (ENEIDA). RESULTS: We included 15 Crohn’s disease patients who received infliximab after adalimumab failure. Five patients discontinued adalimumab due to loss of response, 3 due to adverse events and 7 due to partial response. After infliximab therapy was started, all patients who had interrupted adalimumab due to loss of efficacy regained response. All patients who discontinued adalimumab due to adverse events responded to infliximab and maintained this response; one of these patients had an uneventful course on infliximab, but 2 developed adverse events. None of the 7 patients who interrupted adalimumab due to partial response reached remission with infliximab. CONCLUSION: Switching from adalimumab to infliximab may be useful in patients who develop adverse effects or loss of response, however, the benefit of infliximab in primary nonresponders was not established. PMID:23066316

The catastrophic landfill flowslide at Hongao dumpsite on 20 December 2015 in Shenzhen, China

NASA Astrophysics Data System (ADS)

Xu, Qiang; Peng, Dalei; Li, Weile; Dong, Xiujun; Hu, Wei; Tang, Minggao; Liu, Fangzhou

2017-02-01

A catastrophic flowslide occurred at the Hongao dumpsite on 20 December 2015 in the Guangming New District of Shenzhen, China. The flowslide caused 77 causalities and damaged 33 buildings. In the absence of extreme weather conditions and seismic activity, the causes of the failure were analyzed on the basis of multi-temporal remote-sensing images, site investigation, in situ tests, laboratory tests, and numerical analyses. Site investigations showed that the volume of the displaced material was 2.32 × 106 m3 and the volume of the pre-failure waste filling was 6.27 × 106 m3. The flowslide was characterized by high travel velocity and long runout distance. The displaced material was primarily a mixture of silty soil and construction and demolition waste with water content of 17.3-42.4 %. The primary causes of the failure were concluded to be the following: (1) groundwater flow had stagnated in the dumpsite due to drainage system failure and the underlying impermeable granite stratum; (2) the accumulation rate and total volume of the waste filling was in exceedance of the design capacity. The flowslide may be ascribed to the development of excess pore-water pressure as evidence of liquefaction was observed at several locations, and it is postulated that such phenomena were related to the surcharge loads imposed by the unregulated disposal activities.

Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization

NASA Astrophysics Data System (ADS)

Choi, W. J.; Yeh, E. C. C.; Tu, K. N.

2003-11-01

Electromigration of eutectic SnPb flip chip solder joints and their mean-time-to-failure (MTTF) have been studied in the temperature range of 100 to 140 °C with current densities of 1.9 to 2.75×104 A/cm2. In these joints, the under-bump-metallization (UBM) on the chip side is a multilayer thin film of Al/Ni(V)/Cu, and the metallic bond-pad on the substrate side is a very thick, electroless Ni layer covered with 30 nm of Au. When stressed at the higher current densities, the MTTF was found to decrease much faster than what is expected from the published Black's equation. The failure occurred by interfacial void propagation at the cathode side, and it is due to current crowding near the contact interface between the solder bump and the thin-film UBM. The current crowding is confirmed by a simulation of current distribution in the solder joint. Besides the interfacial void formation, the intermetallic compounds formed on the UBM as well as the Ni(V) film in the UBM have been found to dissolve completely into the solder bump during electromigration. Therefore, the electromigation failure is a combination of the interfacial void formation and the loss of UBM. Similar findings in eutectic SnAgCu flip chip solder joints have also been obtained and compared.

Evidence of an emerging levee failure mechanism causing disastrous floods in Italy

NASA Astrophysics Data System (ADS)

Orlandini, Stefano; Moretti, Giovanni; Albertson, John D.

2015-10-01

A levee failure occurred along the Secchia River, Northern Italy, on 19 January 2014, resulting in flood damage in excess of $500 million. In response to this failure, immediate surveillance of other levees in the region led to the identification of a second breach developing on the neighboring Panaro River, where rapid mitigation efforts were successful in averting a full levee failure. The paired breach events that occurred along the Secchia and Panaro Rivers provided an excellent window on an emerging levee failure mechanism. In the Secchia River, by combining the information content of photographs taken from helicopters in the early stage of breach development and 10 cm resolution aerial photographs taken in 2010 and 2012, animal burrows were found to exist in the precise levee location where the breach originated. In the Panaro River, internal erosion was observed to occur at a location where a crested porcupine den was known to exist and this erosion led to the collapse of the levee top. This paper uses detailed numerical modeling of rainfall, river flow, and variably saturated flow in the levee to explore the hydraulic and geotechnical mechanisms that were triggered along the Secchia and Panaro Rivers by activities of burrowing animals leading to levee failures. As habitats become more fragmented and constrained along river corridors, it is possible that this failure mechanism could become more prevalent and, therefore, will demand greater attention in both the design and maintenance of earthen hydraulic structures as well as in wildlife management.

Evidence of an emerging levee failure mechanism causing disastrous floods in Italy

NASA Astrophysics Data System (ADS)

Orlandini, Stefano; Moretti, Giovanni; Albertson, John

2017-04-01

A levee failure occurred along the Secchia River, Northern Italy, on January 19, 2014, resulting in flood damage in excess of 500 Million. In response to this failure, immediate surveillance of other levees in the region led to the identification of a second breach developing on the neighboring Panaro River, where rapid mitigation efforts were successful in averting a full levee failure. The paired breach events that occurred along the Secchia and Panaro Rivers provided an excellent window on an emerging levee failure mechanism. In the Secchia River, by combining the information content of photographs taken from helicopters in the early stage of breach development and 10-cm resolution aerial photographs taken in 2010 and 2012, animal burrows were found to exist in the precise levee location where the breach originated. In the Panaro River, internal erosion was observed to occur at a location where a crested porcupine den was known to exist and this erosion led to the collapse of the levee top. This paper uses detailed numerical modeling of rainfall, river flow, and variably saturated flow in the levee to explore the hydraulic and geotechnical mechanisms that were triggered along the Secchia and Panaro Rivers by activities of burrowing animals leading to levee failures. As habitats become more fragmented and constrained along river corridors it is possible that this failure mechanism could become more prevalent and, therefore, will demand greater attention in both the design and maintenance of earthen hydraulic structures as well as in wildlife management.

Thermal cycling reliability of Cu/SnAg double-bump flip chip assemblies for 100 μm pitch applications

NASA Astrophysics Data System (ADS)

Son, Ho-Young; Kim, Ilho; Lee, Soon-Bok; Jung, Gi-Jo; Park, Byung-Jin; Paik, Kyung-Wook

2009-01-01

A thick Cu column based double-bump flip chip structure is one of the promising alternatives for fine pitch flip chip applications. In this study, the thermal cycling (T/C) reliability of Cu/SnAg double-bump flip chip assemblies was investigated, and the failure mechanism was analyzed through the correlation of T/C test and the finite element analysis (FEA) results. After 1000 thermal cycles, T/C failures occurred at some Cu/SnAg bumps located at the edge and corner of chips. Scanning acoustic microscope analysis and scanning electron microscope observations indicated that the failure site was the Cu column/Si chip interface. It was identified by a FEA where the maximum stress concentration was located during T/C. During T/C, the Al pad between the Si chip and a Cu column bump was displaced due to thermomechanical stress. Based on the low cycle fatigue model, the accumulation of equivalent plastic strain resulted in thermal fatigue deformation of the Cu column bumps and ultimately reduced the thermal cycling lifetime. The maximum equivalent plastic strains of some bumps at the chip edge increased with an increased number of thermal cycles. However, equivalent plastic strains of the inner bumps did not increase regardless of the number of thermal cycles. In addition, the z-directional normal plastic strain ɛ22 was determined to be compressive and was a dominant component causing the plastic deformation of Cu/SnAg double bumps. As the number of thermal cycles increased, normal plastic strains in the perpendicular direction to the Si chip and shear strains were accumulated on the Cu column bumps at the chip edge at low temperature region. Thus it was found that the Al pad at the Si chip/Cu column interface underwent thermal fatigue deformation by compressive normal strain and the contact loss by displacement failure of the Al pad, the main T/C failure mode of the Cu/SnAg flip chip assembly, then occurred at the Si chip/Cu column interface shear strain deformation during T/C.

Intermediate Temperature Stress Rupture of Woven SiC Fiber, BN Interphase, SiC Matrix Composites in Air

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Levine, Stanley (Technical Monitor)

2000-01-01

Tensile stress-rupture experiments were performed on woven Hi-Nicalon reinforced SiC matrix composites with BN interphases in air. Modal acoustic emission (AE) was used to monitor the damage accumulation in the composites during the tests and microstructural analysis was performed to determine the amount of matrix cracking that occurred for each sample. Fiber fractograph), was also performed for individual fiber failures at the specimen fracture surface to determine the strengths at which fibers failed. The rupture strengths were significantly worse than what would have been expected front the inherent degradation of the fibers themselves when subjected to similar rupture conditions. At higher applied stresses the rate of rupture "?as larger than at lower applied stresses. It was observed that the change in rupture rate corresponded to the onset of through-thickness cracking in the composites themselves. The primary cause of the sen,ere degradation was the ease with which fibers would bond to one another at their closest separation distances, less than 100 nanometers, when exposed to the environment. The near fiber-to-fiber contact in the woven tows enabled premature fiber failure over large areas of matrix cracks due to the stress-concentrations created b), fibers bonded to one another after one or a few fibers fail. i.e. the loss of global load sharing. An@, improvement in fiber-to-fiber separation of this composite system should result in improved stress- rupture properties. A model was den,eloped in order to predict the rupture life-time for these composites based on the probabilistic nature of indin,idual fiber failure at temperature. the matrix cracking state during the rupture test, and the rate of oxidation into a matrix crack. Also incorporated into the model were estimates of the stress-concentration that would occur between the outer rim of fibers in a load-bearing bundle and the unbridged region of a matrix crack after Xia et al. For the lower stresses, this source of stress-concentration was the likely cause for initial fiber failure that would trigger catastrophic failure of the composite.

Effect of Clopidogrel on Early Failure of Arteriovenous Fistulas for Hemodialysis

PubMed Central

Dember, Laura M.; Beck, Gerald J.; Allon, Michael; Delmez, James A.; Dixon, Bradley S.; Greenberg, Arthur; Himmelfarb, Jonathan; Vazquez, Miguel A.; Gassman, Jennifer J.; Greene, Tom; Radeva, Milena K.; Braden, Gregory L.; Ikizler, T. Alp; Rocco, Michael V.; Davidson, Ingemar J.; Kaufman, James S.; Meyers, Catherine M.; Kusek, John W.; Feldman, Harold I.

2016-01-01

Context The arteriovenous fistula is the preferred type of vascular access for hemodialysis because of lower thrombosis and infection rates and lower health care expenditures compared with synthetic grafts or central venous catheters. Early failure of fistulas due to thrombosis or inadequate maturation is a barrier to increasing the prevalence of fistulas among patients treated with hemodialysis. Small, inconclusive trials have suggested that antiplatelet agents may reduce thrombosis of new fistulas. Objective To determine whether clopidogrel reduces early failure of hemodialysis fistulas. Design, Setting, and Participants Randomized, double-blind, placebo-controlled trial conducted at 9 US centers composed of academic and community nephrology practices in 2003–2007. Eight hundred seventy-seven participants with end-stage renal disease or advanced chronic kidney disease were followed up until 150 to 180 days after fistula creation or 30 days after initiation of dialysis, whichever occurred later. Intervention Participants were randomly assigned to receive clopidogrel (300-mg loading dose followed by daily dose of 75 mg; n = 441) or placebo (n = 436) for 6 weeks starting within 1 day after fistula creation. Main Outcome Measures The primary outcome was fistula thrombosis, determined by physical examination at 6 weeks. The secondary outcome was failure of the fistula to become suitable for dialysis. Suitability was defined as use of the fistula at a dialysis machine blood pump rate of 300 mL/min or more during 8 of 12 dialysis sessions. Results Enrollment was stopped after 877 participants were randomized based on a stopping rule for intervention efficacy. Fistula thrombosis occurred in 53 (12.2%) participants assigned to clopidogrel compared with 84 (19.5%) participants assigned to placebo (relative risk, 0.63; 95% confidence interval, 0.46–0.97; P = .018). Failure to attain suitability for dialysis did not differ between the clopidogrel and placebo groups (61.8% vs 59.5%, respectively; relative risk, 1.05; 95% confidence interval, 0.94–1.17; P = .40). Conclusion Clopidogrel reduces the frequency of early thrombosis of new arteriovenous fistulas but does not increase the proportion of fistulas that become suitable for dialysis. Trial Registration clinicaltrials.gov Identifier: NCT00067119 PMID:18477783

Molecular epidemiology of recurrent clinical mastitis due to Streptococcus uberis: evidence of both an environmental source and recurring infection with the same strain.

PubMed

Abureema, Salem; Smooker, Peter; Malmo, Jakob; Deighton, Margaret

2014-01-01

This study was undertaken because clinicians and farmers have observed that a considerable number of cows diagnosed with Streptococcus uberis mastitis have recurrences of mastitis in the same or a different quarter. The study was an attempt to answer whether these recurring cases were due to treatment failure (in which case a search would have begun for a better treatment for Strep. uberis mastitis) or due to reinfection with a different strain of Strep. uberis. Using pulsed-field gel electrophoresis (PFGE), we determined that the majority of recurrences (20 of 27) were caused by a new strain of Strep. uberis, indicating that treatment of the initial infection had been successful. A small number of recurrences (5 of 27) were caused by the initial strain, indicating persistence. The remaining 2 recurrences occurred in a new quarter but with the initial strain of Strep. uberis, indicating either spread between quarters or reactivation of a previous subclinical infection. Analysis of the PFGE profiles failed to reveal any strain-specific propensity to persist, because strains causing recurrences occurred in most of the major clusters. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Annotated bibliography of safety-related occurrences in boiling-water nuclear power plants as reported in 1976

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

Scott, R.L.; Gallaher, R.B.

1977-08-02

This bibliography contains 100-word abstracts of reports to the U.S. Nuclear Regulatory Commission concerning operational events that occurred at boiling-water reactor nuclear power plants in 1976. The report includes 1,253 abstracts that describe incidents, failures, and design or construction deficiencies that were experienced at the facilities. They are arranged alphabetically by reactor name and then chronologically for each reactor. Key-word and permuted-title indexes are provided to facilitate location of the subjects of interest, and tables that summarize the information contained in the bibliography are provided. The information listed in the tables includes instrument failures, equipment failures, system failures, causes ofmore » failures, deficiencies noted, and the time of occurrence (i.e., during refueling, operation, testing, or construction). Three of the unique events that occurred during the year are reviewed in detail.« less

Annotated bibliography of safety-related occurrences in boiling-water nuclear power plants as reported in 1975

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

Scott, R.L.; Gallaher, R.B.

1976-07-01

The bibliography presented contains 100-word abstracts of reports to the U.S. Nuclear Regulatory Commission concerning operational events that occurred at boiling-water reactor nuclear power plants in 1975. The report includes 1169 abstracts, arranged alphabetically by reactor name and then chronologically for each reactor, that describe incidents, failures, and design or construction deficiencies that were experienced at the facilities. Key-word and permuted-title indexes are provided to facilitate location of the subjects of interest, and tables that summarize the information contained in the bibliography are provided. The information listed in the tables includes instrument failures, equipment failures, system failures, causes of failures,more » deficiencies noted, and the time of occurrence (i.e., during refueling, operation, testing, or construction). Seven of the unique events that occurred during the year are reviewed in detail.« less

Annotated bibliography of safety-related occurrences in pressurized-water nuclear power plants as reported in 1975

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

Scott, R.L.; Gallaher, R.B.

1976-07-01

The bibliography presented contains 100-word abstracts of reports to the U.S. Nuclear Regulatory Commission concerning operational events that occurred at pressurized-water reactor nuclear power plants in 1975. The report includes 1097 abstracts, arranged alphabetically by reactor name and then chronologically for each reactor, that describe incidents, failures, and design or construction deficiencies experienced at the facilities. Key-word and permuted-title indexes are provided to facilitate location of the subjects of interest, and tables summarizing the information contained in the bibliography are presented. The information listed in the tables includes instrument failures, equipment failures, system failures, causes of failures, deficiencies noted, andmore » the time of occurrence (i.e., during refueling, operation, testing, or construction). A few of the unique events that occurred during the year are reviewed in detail.« less

Annotated bibliography of safety-related occurrences in pressurized-water nuclear power plants as reported in 1976

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

Scott, R.L.; Gallaher, R.B.

1977-08-01

The bibliography contains 100-word abstracts of reports to the U.S. Nuclear Regulatory Commission concerning operational events that occurred at pressurized-water reactor nuclear power plants in 1976. Included are 1264 abstracts that describe incidents, failures, and design construction deficiencies experienced at the facilities. They are arranged alphabetically by reactor name and then chronologically for each reactor. Key-word and permuted-title indexes are provided to facilitate location of the subjects of interest, and tables summarizing the information contained in the bibliography are presented. The information listed in the tables includes instrument failures, equipment failures, system failures, causes of failures, deficiencies noted, and themore » time of occurrence (i.e., during refueling, operation, testing, or construction). A few of the unique events that occurred during the year are reviewed in detail.« less

Layered clustering multi-fault diagnosis for hydraulic piston pump

NASA Astrophysics Data System (ADS)

Du, Jun; Wang, Shaoping; Zhang, Haiyan

2013-04-01

Efficient diagnosis is very important for improving reliability and performance of aircraft hydraulic piston pump, and it is one of the key technologies in prognostic and health management system. In practice, due to harsh working environment and heavy working loads, multiple faults of an aircraft hydraulic pump may occur simultaneously after long time operations. However, most existing diagnosis methods can only distinguish pump faults that occur individually. Therefore, new method needs to be developed to realize effective diagnosis of simultaneous multiple faults on aircraft hydraulic pump. In this paper, a new method based on the layered clustering algorithm is proposed to diagnose multiple faults of an aircraft hydraulic pump that occur simultaneously. The intensive failure mechanism analyses of the five main types of faults are carried out, and based on these analyses the optimal combination and layout of diagnostic sensors is attained. The three layered diagnosis reasoning engine is designed according to the faults' risk priority number and the characteristics of different fault feature extraction methods. The most serious failures are first distinguished with the individual signal processing. To the desultory faults, i.e., swash plate eccentricity and incremental clearance increases between piston and slipper, the clustering diagnosis algorithm based on the statistical average relative power difference (ARPD) is proposed. By effectively enhancing the fault features of these two faults, the ARPDs calculated from vibration signals are employed to complete the hypothesis testing. The ARPDs of the different faults follow different probability distributions. Compared with the classical fast Fourier transform-based spectrum diagnosis method, the experimental results demonstrate that the proposed algorithm can diagnose the multiple faults, which occur synchronously, with higher precision and reliability.

Is saltmarsh restoration success constrained by matching natural environments or altered succession? A test using niche models.

PubMed

Sullivan, Martin J P; Davy, Anthony J; Grant, Alastair; Mossman, Hannah L

2018-05-01

Restored habitats, such as saltmarsh created through managed realignment, sometimes fail to meet targets for biological equivalence with natural reference sites. Understanding why this happens is important in order to improve restoration outcomes.Elevation in the tidal frame and sediment redox potential are major controls on the distribution of saltmarsh plants. We use niche models to characterize 10 species' responses to these, and test whether differences in species occurrence between restored and natural saltmarshes in the UK result from failure to recreate adequate environmental conditions.Six species occurred less frequently in recently restored marshes than natural marshes. Failure of restored marshes to achieve the elevation and redox conditions of natural marshes partially explained the underrepresentation of five of these species, but did not explain patterns of occurrence on older (>50 years) restored marshes.For all species, an effect of marsh age remained after controlling for differences in environmental conditions. This could be due to differences in successional mechanism between restored and natural marshes. In recently restored marshes, high-marsh species occurred lower in the tidal frame and low-marsh species occurred higher in the tidal frame than in natural marshes. This supports the hypothesis that competition is initially weaker in restored marshes, because of the availability of bare sediment across the whole tidal frame. Species that establish outside their normal realized niche, such as Atriplex portulacoides , may inhibit subsequent colonization of other species that occurred less frequently than expected on older restored marshes. Synthesis and applications . Niche models can be used to test whether abiotic differences between restored sites and their natural counterparts are responsible for discrepancies in species occurrence. In saltmarshes, simply replicating environmental conditions will not result in equivalent species occurrence.

Ultrastructural and cellular basis for the development of abnormal myocardial mechanics during the transition from hypertension to heart failure.

PubMed

Shah, Sanjiv J; Aistrup, Gary L; Gupta, Deepak K; O'Toole, Matthew J; Nahhas, Amanda F; Schuster, Daniel; Chirayil, Nimi; Bassi, Nikhil; Ramakrishna, Satvik; Beussink, Lauren; Misener, Sol; Kane, Bonnie; Wang, David; Randolph, Blake; Ito, Aiko; Wu, Megan; Akintilo, Lisa; Mongkolrattanothai, Thitipong; Reddy, Mahendra; Kumar, Manvinder; Arora, Rishi; Ng, Jason; Wasserstrom, J Andrew

2014-01-01

Although the development of abnormal myocardial mechanics represents a key step during the transition from hypertension to overt heart failure (HF), the underlying ultrastructural and cellular basis of abnormal myocardial mechanics remains unclear. We therefore investigated how changes in transverse (T)-tubule organization and the resulting altered intracellular Ca(2+) cycling in large cell populations underlie the development of abnormal myocardial mechanics in a model of chronic hypertension. Hearts from spontaneously hypertensive rats (SHRs; n = 72) were studied at different ages and stages of hypertensive heart disease and early HF and were compared with age-matched control (Wistar-Kyoto) rats (n = 34). Echocardiography, including tissue Doppler and speckle-tracking analysis, was performed just before euthanization, after which T-tubule organization and Ca(2+) transients were studied using confocal microscopy. In SHRs, abnormalities in myocardial mechanics occurred early in response to hypertension, before the development of overt systolic dysfunction and HF. Reduced longitudinal, circumferential, and radial strain as well as reduced tissue Doppler early diastolic tissue velocities occurred in concert with T-tubule disorganization and impaired Ca(2+) cycling, all of which preceded the development of cardiac fibrosis. The time to peak of intracellular Ca(2+) transients was slowed due to T-tubule disruption, providing a link between declining cell ultrastructure and abnormal myocardial mechanics. In conclusion, subclinical abnormalities in myocardial mechanics occur early in response to hypertension and coincide with the development of T-tubule disorganization and impaired intracellular Ca(2+) cycling. These changes occur before the development of significant cardiac fibrosis and precede the development of overt cardiac dysfunction and HF.

Adjusting survival estimates for premature transmitter failure: A case study from the Sacramento-San Joaquin Delta

USGS Publications Warehouse

Holbrook, Christopher M.; Perry, Russell W.; Brandes, Patricia L.; Adams, Noah S.

2013-01-01

In telemetry studies, premature tag failure causes negative bias in fish survival estimates because tag failure is interpreted as fish mortality. We used mark-recapture modeling to adjust estimates of fish survival for a previous study where premature tag failure was documented. High rates of tag failure occurred during the Vernalis Adaptive Management Plan’s (VAMP) 2008 study to estimate survival of fall-run Chinook salmon (Oncorhynchus tshawytscha) during migration through the San Joaquin River and Sacramento-San Joaquin Delta, California. Due to a high rate of tag failure, the observed travel time distribution was likely negatively biased, resulting in an underestimate of tag survival probability in this study. Consequently, the bias-adjustment method resulted in only a small increase in estimated fish survival when the observed travel time distribution was used to estimate the probability of tag survival. Since the bias-adjustment failed to remove bias, we used historical travel time data and conducted a sensitivity analysis to examine how fish survival might have varied across a range of tag survival probabilities. Our analysis suggested that fish survival estimates were low (95% confidence bounds range from 0.052 to 0.227) over a wide range of plausible tag survival probabilities (0.48–1.00), and this finding is consistent with other studies in this system. When tags fail at a high rate, available methods to adjust for the bias may perform poorly. Our example highlights the importance of evaluating the tag life assumption during survival studies, and presents a simple framework for evaluating adjusted survival estimates when auxiliary travel time data are available.

Severe Respiratory Acidosis in Status Epilepticus as a Possible Etiology of Sudden Death in Lesch-Nyhan Disease: A Case Report and Review of the Literature.

PubMed

Christy, Alison; Nyhan, William; Wilson, Jenny

2017-01-01

Lesch-Nyhan disease (LND) is an X-linked disorder of purine metabolism, associated with self-mutilation, dystonia, and chorea. Seizures are uncommon in LND. Patients with LND are at risk for sudden and unexpected death. The etiology of this is unknown, but appears to occur from a respiratory process. We propose that respiratory failure secondary to subclinical seizure may lead to sudden death in these patients. We report a case of an 11-year-old boy with LND who had two episodes of nocturnal gasping. The second event was immediately followed by a 10 min generalized seizure. Upon arrival at the hospital, an arterial blood gas test revealed a severe respiratory acidosis. Following aggressive treatment of his seizures, this patient did well, and was discharged home on oxcarbazepine with rectal diazepam. No further seizures have been noted in 1 year of follow-up. In this case report and review, we hypothesize that sudden death from respiratory failure in Lesch-Nyhan disease may in some cases be due to seizure-induced respiratory failure, akin to sudden unexpected death in epilepsy (SUDEP). We suggest screening for paroxysmal respiratory events; consideration of electroencephalography for patients with LND presenting in respiratory distress or failure; and consideration of more aggressive treatment of seizures in these patients. Brief Summary:We present an 11-year-old boy with Lesch-Nyhan disease (LND) who developed respiratory failure and severe respiratory acidosis from his first known seizure, which evolved to subclinical status epilepticus. We propose that patients with LND have a predisposition to respiratory failure and sudden death, which in some cases may be provoked by seizure (sudden unexpected death in epilepsy, or SUDEP).

On the indentation failure of carbon-epoxy cross-ply laminates, and its suppression by elasto-plastic interleaves

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

Joergensen, O.; Horsewell, A.

1997-08-01

Elastic and elasto-plastic modelling of indentation in CFRP cross-ply laminates has been performed. Detailed knowledge of the field solutions in the volume below the indentor forms the basis for the reported micromechanical interpretation of the observed damage in test specimens. The analysis shows that matrix cracks originate at sites of maximum tensile stress perpendicular to fibers. The predicted stress fields due to indentation show that stress concentrations occur in the interface between alternating plies. It is found that microcracking in this zone is a precursor to the observed failure. This analysis is supported by in-situ scanning electron microscopy during loadingmore » by a cylindrical indentor onto the laminate supported on a rigid substrate. The microscopy reveals microdamage in the region of interfacial tensile stress concentrations. The onset of indentation failure in these layered composites suggests that plastic interleaves would delay failure. It is shown numerically that plastic deformation of the interleaves redistributes stresses and thereby weakens the tensile stress concentrations which arise during indentation. Experimentally it is shown that aluminium interleaves affect the formation of indentation failure. In a cross-ply laminate, where alternating ply groups are separated by aluminium sheets, matrix cracking and delamination failures are suppressed by the occurrence of plastic deformation. Since the aluminium is likely to be weakly bonded to the plies, it is seen that weak interlaminar fracture toughness does not necessarily cause delaminations, nor lead to a lower indentation strength. High indentation strength and delamination resistance are complex qualities which, among others, seem to be achieved in laminate geometries which have a minimum of stress concentration at interfaces between ply groups of different orientation.« less

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

14 CFR 417.309 - Flight safety system analysis.

Code of Federal Regulations, 2012 CFR

2012-01-01

... system anomaly occurring and all of its effects as determined by the single failure point analysis and... termination system. (c) Single failure point. A command control system must undergo an analysis that... fault tree analysis or a failure modes effects and criticality analysis; (2) Identify all possible...

14 CFR 417.309 - Flight safety system analysis.

Code of Federal Regulations, 2010 CFR

2010-01-01

... system anomaly occurring and all of its effects as determined by the single failure point analysis and... termination system. (c) Single failure point. A command control system must undergo an analysis that... fault tree analysis or a failure modes effects and criticality analysis; (2) Identify all possible...

14 CFR 417.309 - Flight safety system analysis.

Code of Federal Regulations, 2013 CFR

2013-01-01

... system anomaly occurring and all of its effects as determined by the single failure point analysis and... termination system. (c) Single failure point. A command control system must undergo an analysis that... fault tree analysis or a failure modes effects and criticality analysis; (2) Identify all possible...

14 CFR 417.309 - Flight safety system analysis.

Code of Federal Regulations, 2014 CFR

2014-01-01

... system anomaly occurring and all of its effects as determined by the single failure point analysis and... termination system. (c) Single failure point. A command control system must undergo an analysis that... fault tree analysis or a failure modes effects and criticality analysis; (2) Identify all possible...

14 CFR 417.309 - Flight safety system analysis.

Code of Federal Regulations, 2011 CFR

2011-01-01

... system anomaly occurring and all of its effects as determined by the single failure point analysis and... termination system. (c) Single failure point. A command control system must undergo an analysis that... fault tree analysis or a failure modes effects and criticality analysis; (2) Identify all possible...

Applicability of out-of-pile fretting wear tests to in-reactor fretting wear-induced failure time prediction

NASA Astrophysics Data System (ADS)

Kim, Kyu-Tae

2013-02-01

In order to investigate whether or not the grid-to-rod fretting wear-induced fuel failure will occur for newly developed spacer grid spring designs for the fuel lifetime, out-of-pile fretting wear tests with one or two fuel assemblies are to be performed. In this study, the out-of-pile fretting wear tests were performed in order to compare the potential for wear-induced fuel failure in two newly-developed, Korean PWR spacer grid designs. Lasting 20 days, the tests simulated maximum grid-to-rod gap conditions and the worst flow induced vibration effects that might take place over the fuel life time. The fuel rod perforation times calculated from the out-of-pile tests are greater than 1933 days for 2 μm oxidized fuel rods with a 100 μm grid-to-rod gap, whereas those estimated from in-reactor fretting wear failure database may be about in the range of between 60 and 100 days. This large discrepancy in fuel rod perforation may occur due to irradiation-induced cladding oxide microstructure changes on the one hand and a temperature gradient-induced hydrogen content profile across the cladding metal region on the other hand, which may accelerate brittleness in the grid-contacting cladding oxide and metal regions during the reactor operation. A three-phase grid-to-rod fretting wear model is proposed to simulate in-reactor fretting wear progress into the cladding, considering the microstructure changes of the cladding oxide and the hydrogen content profile across the cladding metal region combined with the temperature gradient. The out-of-pile tests cannot be directly applicable to the prediction of in-reactor fretting wear-induced cladding perforations but they can be used only for evaluating a relative wear resistance of one grid design against the other grid design.

A perfect storm: multiple stressors interact to drive postfire regeneration failure of lodgepole pine and Douglas-fir forests in Yellowstone

NASA Astrophysics Data System (ADS)

Hansen, W. D.; Braziunas, K. H.; Rammer, W.; Seidl, R.; Turner, M. G.

2017-12-01

Twenty-first century forests will experience increased stress as environmental conditions and disturbance regimes change. Whether forests retain their structure or transitions to alternate states, particularly when affected by multiple stressors, remains unresolved. Subalpine forests in Yellowstone National Park, WY experience large severe wildfires, and postfire-tree regeneration is necessary to assure resilience. Drying is projected, causing frequent larger wildfires that could reduce seed supply and drought that could constrain postfire-seedling establishment. We asked what combinations of warming-drying conditions, increased fire frequency, and increased burned-patch size cause postfire tree-regeneration failure in Yellowstone? We conducted a simulation experiment to identify combinations of fire frequency, fire size, postfire climate, substrate type, and elevation where lodgepole-pine and Douglas-fir regeneration failed. We expected postfire densities to be reduced if burned-patch sizes exceeded effective dispersal distance, sequential fires burned before trees reached reproductive maturity, or drought occurred after fire. We also expected regeneration failure only where multiple stressors occurred simultaneously at low elevation or on poor substrates.Douglas-fir stands were most vulnerable to regeneration failure. 98% of simulated Douglas-fir stands located in the middle of large burned patches failed to regenerate 30 years post fire. Lodgepole-pine stands in the middle of large burned patches failed to regenerate if they were also located at low elevations (93%) or at higher elevations on soils with poor water retention (73%). Stands of serotinous lodgepole (i.e., trees with closed cones that open when heated) also failed to regenerate if fire recurred before trees were reproductively mature (82%). Drought constrained postfire regeneration, yet, enhanced establishment due to release from cold-temperatures during mid-to-late 21st century often outweighed drought effects. Postfire tree regeneration arises from the interplay between multiple factors; some constraining establishment and others enhancing it. To understand 21st-century climate and fire effects on postfire tree regeneration and forest resilience, a reductionist approach is insufficient.

Innovation Implementation in the Context of Hospital QI: Lessons Learned and Strategies for Success.

PubMed

Rangachari, Pavani

2018-01-01

In 1999, the Institute of Medicine reported that 98,000 people die each year due to medical errors. In the following years, the focus on hospital quality was intensified nationally, with policymakers providing evidence-based practice guidelines for improving health care quality. However, these innovations (evidence-based guidelines) that were being produced at policy levels were not translating to clinical practice at the hospital organizational level easily, and stark variations continued to persist, in the quality of health care. Circa 2009, nearly a decade after the release of the IOM report, the health care organizational literature began referring to this challenge as "innovation implementation failure" in health care organizations (HCOs), ie, failure to implement an evidence-based practice that is new to a HCO. This stream of literature drew upon management research to explain why innovation implementation failure occurs in HCOs and what could be done to prevent it. This paper conducts an integrative review of the literature on "innovation implementation" in hospitals and health systems over the last decade, since the spotlight was cast on "innovation implementation failure" in HCOs. The review reveals that while some studies have retrospectively sought to identify the key drivers of innovation implementation, through surveys and interviews of practitioners (the "what"), other studies have prospectively sought to understand how innovation implementation occurs in hospitals and health systems (the "how"). Both make distinctive contributions to identifying strategies for success in innovation implementation. While retrospective studies have helped identify the key drivers of innovation implementation, prospective studies have shed light on how these drivers could be attained, thereby helping to develop context-sensitive management strategies for success. The literature has called for more prospective research on the implementation and sustainability of health care innovations. This paper summarizes the lessons learned from the literature, discusses the relevance of management research on innovation implementation in HCOs, and identifies future research avenues.

Subfailure injury of the rabbit anterior cruciate ligament.

PubMed

Panjabi, M M; Yoldas, E; Oxland, T R; Crisco, J J

1996-03-01

Ligamentous injuries range in severity from a simple sprain to a complete rupture. Although sprains occur more frequently than complete failures, only a few studies have investigated the phenomena of these subfailure injuries. The purpose of our study was to document the changes in the load-deformation curve until the failure point, after the ligament has been subjected to an 80% subfailure stretch. Thirteen paired fresh rabbit bone-anterior cruciate ligament-bone preparations were used. One of the pairs (control) was stretched until failure; the other (experimental) was first stretched to 80% of the failure deformation of the control and then stretched to failure. Comparisons were made between the load-deformation curves of the experimental and control specimens. The nonlinear load-deformation curves were characterized by eight parameters: failure load (Ffail), failure deformation (Dfail), energy until failure (Efail), deformations measured at 5, 10, 25, and 50% of the failure load (D5, D10, D25, and D50, respectively), and stiffness measured at 50% of the failure force (K50). There were no significant differences in the values for Ffail, Dfail, and Efail between the experimental and control ligaments (p > 0.33). In contrast, the deformation values were all larger for the experimental than the control ligaments (p > 0.01). The deformations D5, D10, D25, and D50 (mean +/- SD) for the control were 0.36 +/- 0.13, 0.49 +/- 0.23, 0.81 +/- 0.35, and 1.23 +/- 0.41 mm. The corresponding deformations for the experimental ligaments were, respectively, 209, 186, 153, and 130% of the control values. K50 was also greater for the experimental ligament (125.0 +/- 41.7 N/mm compared with 108.7 +/- 31.4 N/mm, p < 0.03). These findings indicate that even though the strength of the ligament did not change due to a subfailure injury, the shape of the load-displacement curve, especially at low loads, was significantly altered. Under the dynamic in vivo loading conditions of daily living, this may result in increased joint laxity, additional loads being applied to other joint structures, and, with time, to joint problems.

Mitochondrial fatty acid oxidation alterations in heart failure, ischaemic heart disease and diabetic cardiomyopathy

PubMed Central

Fillmore, N; Mori, J; Lopaschuk, G D

2014-01-01

Heart disease is a leading cause of death worldwide. In many forms of heart disease, including heart failure, ischaemic heart disease and diabetic cardiomyopathies, changes in cardiac mitochondrial energy metabolism contribute to contractile dysfunction and to a decrease in cardiac efficiency. Specific metabolic changes include a relative increase in cardiac fatty acid oxidation rates and an uncoupling of glycolysis from glucose oxidation. In heart failure, overall mitochondrial oxidative metabolism can be impaired while, in ischaemic heart disease, energy production is impaired due to a limitation of oxygen supply. In both of these conditions, residual mitochondrial fatty acid oxidation dominates over mitochondrial glucose oxidation. In diabetes, the ratio of cardiac fatty acid oxidation to glucose oxidation also increases, although primarily due to an increase in fatty acid oxidation and an inhibition of glucose oxidation. Recent evidence suggests that therapeutically regulating cardiac energy metabolism by reducing fatty acid oxidation and/or increasing glucose oxidation can improve cardiac function of the ischaemic heart, the failing heart and in diabetic cardiomyopathies. In this article, we review the cardiac mitochondrial energy metabolic changes that occur in these forms of heart disease, what role alterations in mitochondrial fatty acid oxidation have in contributing to cardiac dysfunction and the potential for targeting fatty acid oxidation to treat these forms of heart disease. LINKED ARTICLES This article is part of a themed issue on Mitochondrial Pharmacology: Energy, Injury & Beyond. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2014.171.issue-8 PMID:24147975

Risk assessment of Giardia from a full scale MBR sewage treatment plant caused by membrane integrity failure.

PubMed

Zhang, Yu; Chen, Zhimin; An, Wei; Xiao, Shumin; Yuan, Hongying; Zhang, Dongqing; Yang, Min

2015-04-01

Membrane bioreactors (MBR) are highly efficient at intercepting particles and microbes and have become an important technology for wastewater reclamation. However, many pathogens can accumulate in activated sludge due to the long residence time usually adopted in MBR, and thus may pose health risks when membrane integrity problems occur. This study presents data from a survey on the occurrence of water-borne Giardia pathogens in reclaimed water from a full-scale wastewater treatment plant with MBR experiencing membrane integrity failure, and assessed the associated risk for green space irrigation. Due to membrane integrity failure, the MBR effluent turbidity varied between 0.23 and 1.90 NTU over a period of eight months. Though this turbidity level still met reclaimed water quality standards (≤5 NTU), Giardia were detected at concentrations of 0.3 to 95 cysts/10 L, with a close correlation between effluent turbidity and Giardia concentration. All β-giardin gene sequences of Giardia in the WWTP influents were genotyped as Assemblages A and B, both of which are known to infect humans. An exponential dose-response model was applied to assess the risk of infection by Giardia. The risk in the MBR effluent with chlorination was 9.83×10(-3), higher than the acceptable annual risk of 1.0×10(-4). This study suggested that membrane integrity is very important for keeping a low pathogen level, and multiple barriers are needed to ensure the biological safety of MBR effluent. Copyright © 2015. Published by Elsevier B.V.

Ground-based LiDAR application to characterize sea cliff instability processes along a densely populated coastline in Southern Italy

NASA Astrophysics Data System (ADS)

Esposito, Giuseppe; Semaan, Fouad; Salvini, Riccardo; Troise, Claudia; Somma, Renato; Matano, Fabio; Sacchi, Marco

2017-04-01

Sea cliff retreatment along the coastline of the Campi Flegrei volcanic area (Southern Italy) is becoming a threat for public and private structures due to the massive urbanization occurred in the last few decades. In this area, geological features of the outcropping rocks represent one of the most important factors conditioning the sea cliff retreatment. In fact, pyroclastic deposits formed by pumices, scoria, ashes and lapilli are arranged in weakly to moderately welded layers of variable thicknesses, resulting very erodible and prone to landslide processes. Available methods to evaluate topographic changes and retreat rates of sea cliffs include a variety of geomatic techniques, like terrestrial and aerial photogrammetry and LiDAR (Light Detection And Ranging). By means of such techniques, it is in fact possible to obtain high resolution topography of sea cliffs and perform multi-temporal change detection analysis. In this contribution, we present an application of Terrestrial Laser Scanning (TLS or ground-based LiDAR) aimed to identify and quantify instability processes acting along the Torrefumo coastal cliff, in the Campi Flegrei area. Specifically, we acquired a series of 3D point clouds on the years 2013 and 2016, and compared them through a cloud-to-cloud distance computation. Furthermore, a statistical analysis was applied to the change detection results. In this way, an inventory of the cliff failures occurred along the Torrefumo cliff in the 2013-2016 time span was created, as well as the spatial and volumetric distribution of these failures was evaluated. The volumetric analysis shows that large collapses occurred rarely, whereas the spatial analysis shows that the majority of failures occurred in the middle and upper parts of the cliff face. Results also show that both rock fall and surficial erosion processes contribute to the cliff retreatment, acting in turn according to the geological properties of the involved pyroclastic deposits. The presented TLS approach proves to be a cost and time efficient method for characterizing the geomorphic changes involving the sea cliff surfaces over a short-time period (i.e. monthly or yearly). The accuracy of the acquired data allows the characterization of a full range of failures to be located and quantified with a level of detail not reachable using traditional techniques. Results obtained in this research will be used in future applications to assess hazard conditions affecting the anthropic structures built close to the cliff top.

Enhancing the Cassini Mission Through FP Applications After Launch

NASA Technical Reports Server (NTRS)

Morgan, Paula S.

2016-01-01

Although rigorous pre-emptive measures are taken to preclude failures and anomalous conditions from occurring in JPL spacecraft missions prior to launch, unforeseeable problems can still surface after liftoff. In the case of the Cassini/Huygens Mission-to-Saturn spacecraft, several problems were observed post-launch: 1) immediately after takeoff, the collected engineering/science data stored on the Solid State Recorders (SSR) contained a significantly higher number of corrupted bits than was expected (considerably over spec) due to human error in the memory mapping of these devices, 2) numerous Solid State Power Switches (SSPS) sporadically tripped off throughout the mission due to cosmic ray bombardment from the unique space environment, and 3) false assumptions in the pressure regulator design in combination with missing heritage test data led to inaccurate design conclusions, causing the issuance of two waivers for the regulator to close properly (a potentially mission catastrophic single-point failure which occurred 24 days after launch) - amongst other problems. For Cassini, some of these anomalies led to arduous work-arounds or required continuous monitoring of telemetry variables by the ground-based Spacecraft Operations Flight Support (SOFS) team in order to detect and fix fault occurrences as they happened. Fortunately, sufficient funding and schedule margin allowed several Fault Protection (FP) solutions to be implemented into post-launch Flight Software (FSW) uploads to help resolve these issues autonomously, reducing SOFS ground support efforts while improving anomaly recovery time in order to preserve maximum science capture. This paper details the FP applications used to resolve the above issues as well as to optimize solutions for several other problems experienced by the Cassini spacecraft during its fight, in order to enhance the spacecraft's overall mission success throughout the 18 years of its 20 year expedition to and within the Saturnian system.

Rapid-onset plasma leakage of extracorporeal oxygenation membranes possibly due to hyperbilirubinemia.

PubMed

Kida, Yoshiko; Ohshimo, Shinichiro; Kyo, Michihito; Tanabe, Yuko; Suzuki, Kei; Hosokawa, Koji; Shime, Nobuaki

2018-06-02

Extracorporeal membrane oxygenation (ECMO) is an emerging tool for supporting cardiopulmonary function in patients with cardiorespiratory failure or arrest. The oxygenator of the ECMO circuit requires effective oxygenation and removal of carbon dioxide from the blood. Major problems that can occur with the oxygenator include plasma leakage, one of the late-onset serious complications necessitating device replacement. However, the rapid onset of plasma leakage is rare. We present a 1-year-old boy with acute respiratory failure due to Pneumocystis and Aspergillus pneumonia. He presented with tachypnea, tachycardia, and hypoxemia despite the ventilatory support, and was therefore placed on venoarterial ECMO with a drainage catheter from the right internal jugular vein (12 Fr) and a return catheter to the right internal carotid artery (10 Fr). Extracorporeal circulation was initiated at a blood flow of 1 L/min (145 mL/kg/min) and a sweep gas flow of 1 L/min with FiO 2 of 0.7. Although he was successfully weaned from the venoarterial ECMO on day 15 with an improvement of cardiopulmonary function, he was later placed on venoarterial ECMO again because of the progression of pulmonary hypertension. Laboratory tests showed increased concentrations of hepatic enzymes and hyperbilirubinemia (total bilirubin 31.6 mg/dL). Six hours after starting ECMO circulation, plasma leakage from the oxygenator occurred. Although we replaced the oxygenator with a new one, the replacement showed plasma leakage after 6 h. Disassembly of the oxygenator revealed congestion from bilirubin in the membrane fibers. We described a case of repeated, rapid-onset plasma leakage after implementation of ECMO. Hyperbilirubinemia was likely associated with the plasma leakage of this patient.

Anesthetic cartridge system under evaluation.

PubMed

Cooley, R L; Lubow, R M

1981-01-01

The problem of glass breakage in the local anesthetic cartridge system was evaluated under laboratory conditions with a mechanical testing machine. The anticipated breakage of the glass did not occur with any frequency, as the rubber stopper produced more uniform failures of the system. The glass cartridge appeared to be quite reliable and resistant to breakage.Local anesthetics have been used for many years to provide patients temporary freedom from pain. Local anesthetic solutions are in wide use in both dentistry and medicine and are the most frequently used drugs in dentistry. Various estimates place the number of injections at approximately one half million daily or 125 million injections per year.These drugs and the armamentarium necessary to administer them have proven to be safe and reliable. Only rarely are there reports of sensitivity to the anesthetic solution or breakage of needles.. Sterility of the solutions has not been a problem as they are carefully processed and evaluated at the factory. Although there are sporadic reports of loss of sterility, this has been attributed to the reuse of the anesthetic cartridges on more than one patient. Monheim states "The success of the cartridge system in dentistry has been due to the sincerity, honesty, and high standards of the manufacturers in giving the profession a near-perfect product." However, on occassion a glass cartridge will break or shatter when inserting the harpoon into the rubber stopper or even during injection. Cooley et al reported on eye injuries occurring in the dental office, one of which was due to glass from a local anesthetic cartridge that exploded and propelled particles into the patient's eye. Forrest evaluated syringes, needles, and cartridges and reported that one brand (made in Britain) fractured more often than any other, but that the fracture rate was too low to be of any consequence.It is apparent that glass cartridges will fracture or burst from time to time. This study evaluates the cartridge system with carefully controlled laboratory procedures. The cartridges were tested under various pressures and conditions in an attempt to determine the causes of failure and when such failure may be anticipated.

Coupling between the spinal cord and cervical vertebral column under tensile loading.

PubMed

Kroeker, Shannon G; Ching, Randal P

2013-02-22

Current neck injury criteria are based on structural failure of the spinal (vertebral) column without consideration of injury to the spinal cord. Since one of the primary functions of the vertebral column is to protect the cord, it stands to reason that a more refined measure of neck injury threshold would be the onset of spinal cord injury (SCI). This study investigated the relationship between axial strains in the cervical vertebral column and the spinal cord using an in vitro primate model (n=10) under continuous tensile loading. Mean failure loads occurred at 1951.5±396N with failure strains in the vertebral column of 16±5% at the level of failure. Average tensile strains in the spinal cord at failure were 11±5% resulting in a mean coupling ratio of 0.54±0.17 between C1 and C7. The level of peak strain measured in the spinal cord did not always occur at the location of vertebral column failure. Spinal cord strains were less than spine strains and coupling ratios were not significantly different along the length of the spine. The largest coupling ratio was measured in the atlanto-occipital joint whereas the smallest coupling ratio occurred at the adjacent C1-C2 joint. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bootstrap imputation with a disease probability model minimized bias from misclassification due to administrative database codes.

PubMed

van Walraven, Carl

2017-04-01

Diagnostic codes used in administrative databases cause bias due to misclassification of patient disease status. It is unclear which methods minimize this bias. Serum creatinine measures were used to determine severe renal failure status in 50,074 hospitalized patients. The true prevalence of severe renal failure and its association with covariates were measured. These were compared to results for which renal failure status was determined using surrogate measures including the following: (1) diagnostic codes; (2) categorization of probability estimates of renal failure determined from a previously validated model; or (3) bootstrap methods imputation of disease status using model-derived probability estimates. Bias in estimates of severe renal failure prevalence and its association with covariates were minimal when bootstrap methods were used to impute renal failure status from model-based probability estimates. In contrast, biases were extensive when renal failure status was determined using codes or methods in which model-based condition probability was categorized. Bias due to misclassification from inaccurate diagnostic codes can be minimized using bootstrap methods to impute condition status using multivariable model-derived probability estimates. Copyright © 2017 Elsevier Inc. All rights reserved.

Role of failure-mechanism identification in accelerated testing

NASA Technical Reports Server (NTRS)

Hu, J. M.; Barker, D.; Dasgupta, A.; Arora, A.

1993-01-01

Accelerated life testing techniques provide a short-cut method to investigate the reliability of electronic devices with respect to certain dominant failure mechanisms that occur under normal operating conditions. However, accelerated tests have often been conducted without knowledge of the failure mechanisms and without ensuring that the test accelerated the same mechanism as that observed under normal operating conditions. This paper summarizes common failure mechanisms in electronic devices and packages and investigates possible failure mechanism shifting during accelerated testing.

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

NASA Technical Reports Server (NTRS)

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

1972-01-01

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

No Trespassing: What Every Alien Needs to Know.

ERIC Educational Resources Information Center

Hyde, Sheila A.; Carpenter, D. Stanley

1992-01-01

Examines what might occur when staff members change positions and offers suggestions for the "alien" venturing into unfamiliar territory. Discusses ways in which an alien may trespass: inappropriate enthusiasm for the new place; failure to fit into the system; inappropriate comparisons; failure to define success; failure to deal with failing; and…

Nonacetaminophen Drug-Induced Acute Liver Failure.

PubMed

Thomas, Arul M; Lewis, James H

2018-05-01

Acute liver failure of all causes is diagnosed in between 2000 and 2500 patients annually in the United States. Drug-induced acute liver failure is the leading cause of acute liver failure, accounting for more than 50% of cases. Nonacetaminophen drug injury represents 11% of all cases in the latest registry from the US Acute Liver Failure Study Group. Although rare, acute liver failure is clinically dramatic when it occurs, and requires a multidisciplinary approach to management. In contrast with acetaminophen-induced acute liver failure, non-acetaminophen-induced acute liver failure has a more ominous prognosis with a lower liver transplant-free survival. Copyright © 2018 Elsevier Inc. All rights reserved.

Hypokalemic muscular paralysis causing acute respiratory failure due to rhabdomyolysis with renal tubular acidosis in a chronic glue sniffer.

PubMed

Kao, K C; Tsai, Y H; Lin, M C; Huang, C C; Tsao, C Y; Chen, Y C

2000-01-01

A 34-year-old male was admitted to the emergency department with the development of quadriparesis and respiratory failure due to hypokalemia after prolonged glue sniffing. The patient was subsequently given mechanical ventilatory support for respiratory failure. He was weaned from the ventilator 4 days later after potassium replacement. Toluene is an aromatic hydrocarbon found in glues, cements, and solvents. It is known to be toxic to the nervous system, hematopoietic system, and causes acid-base and electrolyte disorders. Acute respiratory failure with hypokalemia and rhabdomyolysis with acute renal failure should be considered as potential events in a protracted glue sniffing.

Catastrophic failures of freezing bags for cellular therapy products: description, cause, and consequences.

PubMed

Khuu, H M; Cowley, H; David-Ocampo, V; Carter, C S; Kasten-Sportes, C; Wayne, A S; Solomon, S R; Bishop, M R; Childs, R M; Read, E J

2002-01-01

Container integrity is critical for maintaining sterility of cryopreserved cellular therapy products. We investigated a series of catastrophic bag failures, first noticed in early 2001. Process records were reviewed for all PBPC and lymphocyte products cryopreserved in bags from January 2000 through April 2002. Patient charts were also reviewed. One thousand two hundred and four bags were removed from storage for infusion to 261 patients. All products had been cryopreserved in Cryocyte poly(ethylene co-vinyl acetate) (EVA) bags in either 10% DMSO or 5% DMSO and 6% pentastarch. Product volumes were 25-75 mL, and bags were stored with overwrap bags in a liquid nitrogen tank. From January 2000 to April 2001, failure occurred in 10 of 599 (1.7%) bags. From May 2001 to April 2002, 58 of 605 (9.6%) bags failed, typically with extensive fractures that were visible before thaw. Of the 58 that failed, 24 were salvaged by aseptic methods and infused to patients under antibiotic coverage; 10 of those 24 (42%) had positive bacterial cultures. Bag failures were not related to product type, cryoprotectant solution, liquid versus vapor storage, or freezer location. Failures were linked to use of four Cryocyte bag lots manufactured in 2000 and 2001. After replacing these lots with a 1999 Cryocyte lot and with KryoSafe polyfluoroethylene polyfluoropropylene (FEP) bags, no more failures occurred in 75 and 102 bags, respectively, thawed through April 2002. High rates of bag failure were associated with four Cryocyte bag lots. No serious adverse patient effects occurred, but bag failures led to microbial contamination, increased product preparation time, increased antibiotic use, and increased resource expenditure to replace products.

A two-stage model of fracture of rocks

USGS Publications Warehouse

Kuksenko, V.; Tomilin, N.; Damaskinskaya, E.; Lockner, D.

1996-01-01

In this paper we propose a two-stage model of rock fracture. In the first stage, cracks or local regions of failure are uncorrelated occur randomly throughout the rock in response to loading of pre-existing flaws. As damage accumulates in the rock, there is a gradual increase in the probability that large clusters of closely spaced cracks or local failure sites will develop. Based on statistical arguments, a critical density of damage will occur where clusters of flaws become large enough to lead to larger-scale failure of the rock (stage two). While crack interaction and cooperative failure is expected to occur within clusters of closely spaced cracks, the initial development of clusters is predicted based on the random variation in pre-existing Saw populations. Thus the onset of the unstable second stage in the model can be computed from the generation of random, uncorrelated damage. The proposed model incorporates notions of the kinetic (and therefore time-dependent) nature of the strength of solids as well as the discrete hierarchic structure of rocks and the flaw populations that lead to damage accumulation. The advantage offered by this model is that its salient features are valid for fracture processes occurring over a wide range of scales including earthquake processes. A notion of the rank of fracture (fracture size) is introduced, and criteria are presented for both fracture nucleation and the transition of the failure process from one scale to another.

Testicular failure

MedlinePlus

... Testicular failure occurs when the testicles cannot produce sperm or male hormones, such as testosterone. Causes Testicular ... semen analysis to examine the number of healthy sperm you are producing. Sometimes, an ultrasound of the ...

Neonatal circulatory failure due to acute hypertensive crisis: clinical and echocardiographic clues.

PubMed

Louw, Jacoba; Brown, Stephen; Thewissen, Liesbeth; Smits, Anne; Eyskens, Benedicte; Heying, Ruth; Cools, Bjorn; Levtchenko, Elena; Allegaert, Karel; Gewillig, Marc

2013-04-01

Circulatory failure due to acute arterial hypertension in the neonatal period is rare. This study was undertaken to assess the clinical and echocardiographic manifestations of circulatory failure resulting from acute neonatal hypertensive crisis. Neonatal and cardiology databases from 2007 to 2010 were reviewed. An established diagnosis of circulatory failure due to neonatal hypertension before the age of 14 days was required for inclusion. Six patients were identified. Five patients presented with circulatory failure due to an acute hypertensive crisis. The median age at presentation was 8.5 days (range: 6.0-11.0) with a median body weight of 3.58 kg (range: 0.86-4.70). Echocardiography demonstrated mild left ventricular dysfunction [median shortening fraction (SF) 25%, range 10-30] and mild aortic regurgitation in 83% (5/6) of patients. One patient with left ventricular dysfunction (SF = 17%) had a large apical thrombus. Two patients were hypotensive, and hypertension only became evident after restoration of cardiac output. Administration of intravenous milrinone was successful, with rapid improvement of the clinical condition. Left ventricular function normalised in all survivors. Early neonatal circulatory collapse due to arterial hypertension is a rare but potentially life-threatening condition. At presentation, hypotension, especially in the presence of a dysfunctional left ventricle, does not exclude a hypertensive crisis being the cause of circulatory failure. The echocardiographic presence of mild aortic regurgitation combined with left ventricular hypocontractility in a structurally normal heart should alert the physician to the presence of underlying hypertension.

Preventing Precipitation in the ISS Urine Processor

NASA Technical Reports Server (NTRS)

Muirhead, Dean; Carter, Layne; Williamson, Jill; Chambers, Antja

2017-01-01

The ISS Urine Processor Assembly (UPA) was initially designed to achieve 85% recovery of water from pretreated urine on ISS. Pretreated urine is comprised of crew urine treated with flush water, an oxidant (chromium trioxide), and an inorganic acid (sulfuric acid) to control microbial growth and inhibit precipitation. Unfortunately, initial operation of the UPA on ISS resulted in the precipitation of calcium sulfate at 85% recovery. This occurred because the calcium concentration in the crew urine was elevated in microgravity due to bone loss. The higher calcium concentration precipitated with sulfate from the pretreatment acid, resulting in a failure of the UPA due to the accumulation of solids in the Distillation Assembly. Since this failure, the UPA has been limited to a reduced recovery of water from urine to prevent calcium sulfate from reaching the solubility limit. NASA personnel have worked to identify a solution that would allow the UPA to return to a nominal recovery rate of 85%. This effort has culminated with the development of a pretreatment based on phosphoric acid instead of sulfuric acid. By eliminating the sulfate associated with the pretreatment, the brine can be concentrated to a much higher concentration before calcium sulfate reach the solubility limit. This paper summarizes the development of this pretreatment and the testing performed to verify its implementation on ISS.

Does chlorination of seawater reverse osmosis membranes control biofouling?

PubMed

Khan, Muhammad Tariq; Hong, Pei-Ying; Nada, Nabil; Croue, Jean Philippe

2015-07-01

Biofouling is the major problem of reverse osmosis (RO) membranes used for desalting seawater (SW). The use of chlorine is a conventional and common practice to control/prevent biofouling. Unlike polyamide RO membranes, cellulose triacetate (CTA) RO membranes display a high chlorine tolerance. Due to this characteristic, CTA membranes are used in most of the RO plants located in the Middle East region where the elevated seawater temperature and water quality promote the risk of membrane biofouling. However, there is no detailed study on the investigation/characterization of CTA-RO membrane fouling. In this investigation, the fouling profile of a full-scale SWRO desalination plant operating with not only continuous chlorination of raw seawater but also intermittent chlorination of CTA-RO membranes was studied. Detailed water quality and membrane fouling analyses were conducted. Profiles of microbiological, inorganic, and organic constituents of analysed fouling layers were extensively discussed. Our results clearly identified biofilm development on these membranes. The incapability of chlorination on preventing biofilm formation on SWRO membranes could be assigned to its failure in effectively reaching throughout the different regions of the permeators. This failure could have occurred due to three main factors: plugging of membrane fibers, chlorine consumption by organics accumulated on the front side fibers, or chlorine adaptation of certain bacterial populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Septic shock due to community-acquired complicated intra-abdominal infection treated with ertapenem: outcome in 25 cases].

PubMed

Maseda, E; Lillo, M; Fernández, L; Villagrán, M J; Gómez-Rice, A; Ramasco, F

2008-04-01

To assess the effectiveness of ertapenem in patients admitted to a surgical intensive care unit with septic shock due to community-acquired complicated intra-abdominal infection. Patients undergoing emergency surgery for community-acquired complicated intra-abdominal infection were enrolled prospectively. All patients were given intravenous ertapenem at a rate of 1 g/24 h and the guidelines of the Surviving Sepsis Campaign were applied. Outcome measures were duration of antibiotic therapy, mean length of stay in the surgical intensive care unit (ICU), antibiotic failure, and death while in the surgical ICU. Twenty-five patients with a mean (SD) age of 74 (14) years were enrolled. The origin of infection was the colon in 56% of the cases; most patients (76%) had generalized peritonitis. The mean stay in the surgical ICU was 10 (7) days. The mean duration of antibiotic therapy was 5.8 (1.26) days. Antibiotic failure occurred in 12%. Mortality in the surgical ICU was 28%. Our findings suggest that patients with community-acquired intra-abdominal infection and septic shock have a good chance of survival when treated according to the guidelines of the Surviving Sepsis Campaign. Ertapenem seems to give good results when used in this setting.

Patients with 47, XXX karyotype who experienced premature ovarian failure (POF): two case reports.

PubMed

Sugawara, Nobuo; Maeda, Machiko; Manome, Tomomi; Nagai, Rie; Araki, Yasuhisa

2013-10-01

Pubertal onset and sexual development are usually normal in 47, XXX individuals; however, we report two cases of premature ovarian failure (POF) in infertile women with trisomy X. Chromosome analysis was conducted with G-banding and fluorescence in situ hybridization using X- and Y-bearing probe. Hormonal administration was primarily Kaufmann's treatment or long-term estradiol treatment, followed by withdrawal bleeding from estrogen and progesterone. Two patients with trisomy X, aged 31 (patient 1) and 27 years (patient 2), were diagnosed with POF due to hypergonadotropic hypogonadism. Their ovaries were small. Patient 1 had a FSH level of 44.6 mIU/ml and patient 2 had a FSH level of 74.6 mIU/ml. In patient 1, with Kaufmann's treatment, the FSH decreased to 13.5 mIU/ml; however, follicle growth did not occur following HMG stimulation. In patient 2, FSH did not decrease despite Kaufmann's treatment; therefore, she was given a GnRH agonist and her FSH level decreased to 7.1 mIU/ml. However, her ovaries never responded to HMG stimulation. We report on two patients with a 47, XXX karyotype who became infertile due to POF. We recommend that when a patient is diagnosed with trisomy X, the possibility of POF must be strongly considered.

Infant botulism due to consumption of contaminated commercially prepared honey. First report from the Arabian Gulf States.

PubMed

van der Vorst, Maria M J; Jamal, Wafaa; Rotimi, Vincent O; Moosa, Alie

2006-01-01

To report the first case of infant botulism in Arabian Gulf States. A 6-week-old infant, presenting with signs of sepsis, was intubated and ventilated due to progressive weakness. Infant botulism was suspected with acute flaccid paralysis and a history of honey consumption. An electromyogram showed decreased amplitude of compound muscle action potential in all motor nerves, preserved sensory responses; the motor terminal latencies and motor conduction velocities were normal. Blood, stool and honey samples were sent for culture. Stool and honey cultures showed two identical strains of Clostridium botulinum. This case shows that the infant botulism occurred from the ingested contaminated honey. Hence vigilance should be maintained when a baby is fed honey and shows signs of progressive weakness because the disease can quickly progress to respiratory failure.

Decellularized Allografts for Right Ventricular Outflow Tract Reconstruction in Children.

PubMed

da Costa, Francisco Diniz Affonso; Etnel, Jonathan R G; Torres, Renato; Balbi Filho, Eduardo M; Torres, Rafael; Calixto, Allyson; Mulinari, Leonardo A

2017-09-01

Determine the midterm outcomes of decellularized allografts for right ventricular outflow tract (RVOT) reconstruction in children less than 12 years of age. The study included all consecutive patients submitted to RVOT reconstruction with decellularized allografts between June 2006 and June 2016. Besides clinical and echocardiographic control, 20 patients with more than five years of follow-up were evaluated with computed tomography (CT) scans to determine allograft diameters and calcium scores. Structural valve deterioration was defined as any peak gradient above 40 mm Hg and/or insufficiency of moderate or severe degree. Conduit failure was defined as the need for allograft reintervention. There were 59 patients with a median age of six years (range = 0.01-12 years). The most common operation was the Ross procedure (34%). Mean clinical follow-up was 5.4 (2.8) years and was 94% complete. At eight years, only two patients needed a reintervention, with a 90.9% freedom from this event. Structural valve deterioration occurred in 13 patients, 5 due to stenosis and 8 due to insufficiency, with a freedom from structural valve deterioration due to any cause of 64.9% at eight years. Late CT scans demonstrated the absence or minimal calcification of the conduits. Decellularized allografts for RVOT reconstruction in children were associated with a low incidence of structural valve deterioration and conduit failure. Although these results still need to be confirmed in larger series and with longer follow-up, our data suggest favorable outcomes, at least in the first decade after the operation.

Ultrasonic Evaluation of Fatigue Damage

NASA Astrophysics Data System (ADS)

Bayer, P.; Singher, L.; Notea, A.

2004-02-01

Despite the fact that most engineers and designers are aware of fatigue, many severe breakdowns of industrial plant and machinery still occur due to fatigue. In effect, it's been estimated that fatigue causes at least 80% of the failures in modern engineering components. From an operational point of view, the detection of fatigue damage, preferably at a very early stage, is a critically important consideration in order to prevent possible catastrophic equipment failure and associated losses. This paper describes the investigation involving the use of ultrasonic waves as a potential tool for early detection of fatigue damage. The parameters investigated were the ultrasonic wave velocities (longitudinal and transverse waves) and attenuation coefficient before fatigue damage and after progressive stages of fatigue. Although comparatively small uncertainties were observed, the feasibility of utilizing the velocity of ultrasonic waves as a fatigue monitor was barely substantiated within actual research conditions. However, careful measurements of the ultrasonic attenuation parameter had demonstrated its potential to provide an early assessment of damage during fatigue.

Modeling and characterization of partially inserted electrical connector faults

NASA Astrophysics Data System (ADS)

Tokgöz, ćaǧatay; Dardona, Sameh; Soldner, Nicholas C.; Wheeler, Kevin R.

2016-03-01

Faults within electrical connectors are prominent in avionics systems due to improper installation, corrosion, aging, and strained harnesses. These faults usually start off as undetectable with existing inspection techniques and increase in magnitude during the component lifetime. Detection and modeling of these faults are significantly more challenging than hard failures such as open and short circuits. Hence, enabling the capability to locate and characterize the precursors of these faults is critical for timely preventive maintenance and mitigation well before hard failures occur. In this paper, an electrical connector model based on a two-level nonlinear least squares approach is proposed. The connector is first characterized as a transmission line, broken into key components such as the pin, socket, and connector halves. Then, the fact that the resonance frequencies of the connector shift as insertion depth changes from a fully inserted to a barely touching contact is exploited. The model precisely captures these shifts by varying only two length parameters. It is demonstrated that the model accurately characterizes a partially inserted connector.

The discovery of the pressor effect of DOPS and its blunting by decarboxylase inhibitors.

PubMed

Kaufmann, H

2006-01-01

In the 1950s it was found that an artificial aminoacid, 3,4-threo-dihydroxyphenylserine (DOPS), was converted to norepinephrine (NE) in a single step by the enzyme L-aromatic amino acid decarboxylase (AADC), bypassing the need for the rate limiting enzyme dopamine beta hydroxylase. Trying to replicate the success of dihydroxyphenylalanine (DOPA) in the treatment of Parkinson disease, treatment with DOPS was attempted in patients with autonomic failure who have impaired NE release. DOPS improved orthostatic hypotension in patients with familial amyloid polyneuropathy, congenital deficiency of dopamine beta hydroxylase, pure autonomic failure and multiple system atrophy. DOPS pressor effect is due to its conversion to NE outside the central nervous system because concomitant administration of carbidopa, an inhibitor of AADC that does not cross the blood-brain barrier, blunted both the increase in plasma NE and the pressor response. DOPS pressor response is not dependent on intact sympathetic terminals because its conversion to NE also occurs in non-neuronal tissues.

Inattentional blindness reflects limitations on perception, not memory: Evidence from repeated failures of awareness.

PubMed

Ward, Emily J; Scholl, Brian J

2015-06-01

Perhaps the most striking phenomenon of visual awareness is inattentional blindness (IB), in which a surprisingly salient event right in front of you may go completely unseen when unattended. Does IB reflect a failure of perception, or only of subsequent memory? Previous work has been unable to answer this question, due to a seemingly intractable dilemma: ruling out memory requires immediate perceptual reports, but soliciting such reports fuels an expectation that eliminates IB. Here we introduce a way of evoking repeated IB in the same subjects and the same session: we show that observers fail to report seeing salient events' not only when they have no expectation, but also when they have the wrong expectations about the events nature. This occurs when observers must immediately report seeing anything unexpected, even mid-event. Repeated IB thus demonstrates that IB is aptly named: it reflects a genuine deficit in moment-by-moment conscious perception, rather than a form of inattentional amnesia.

Fatal course of takotsubo cardiomyopathy in a female with recurrent Clostridium difficile infection.

PubMed

Elikowski, Waldemar; Małek-Elikowska, Małgorzata; Lisiecka, Monika; Mozer-Lisewska, Iwona

2017-06-23

Among diverse triggering factors of stress-induced takotsubo cardiomyopathy (TC), a viral or bacterial infection is rarely observed. Sepsis is an exception, regardless of the etiologic pathogen, in which case an excess of catecholamines may result in acute left ventricular dysfunction. TC precipitated by Clostridium difficile infection (CDI) has been reported only in two patients so far. The authors describe another case of TC triggered this time by recurrent C. difficile colitis which occurred in a 72-yearold female. Severe heart failure developed on the second day of a new episode of diarrhea. Echocardiography revealed apical ballooning, a typical form of TC, while the coronary arteries in coronary angiography were normal. Despite proper treatment of CDI, the course of the disease was fatal due to heart failure progression. In considerations of TC pathogenesis in the case presented, the impact of C. difficile toxins should be taken into account. One should remember about the potential extraintestinal complications of CDI, including sudden myocardial depression.

An Examination of Commercial Aviation Accidents and Incidents Related to Integrated Vehicle Health Management

NASA Technical Reports Server (NTRS)

Reveley, Mary S.; Briggs, Jeffrey L.; Thomas, Megan A.; Evans, Joni K.; Jones, Sharon M.

2011-01-01

The Integrated Vehicle Health Management (IVHM) Project is one of the four projects within the National Aeronautics and Space Administration's (NASA) Aviation Safety Program (AvSafe). The IVHM Project conducts research to develop validated tools and technologies for automated detection, diagnosis, and prognosis that enable mitigation of adverse events during flight. Adverse events include those that arise from system, subsystem, or component failure, faults, and malfunctions due to damage, degradation, or environmental hazards that occur during flight. Determining the causal factors and adverse events related to IVHM technologies will help in the formulation of research requirements and establish a list of example adverse conditions against which IVHM technologies can be evaluated. This paper documents the results of an examination of the most recent statistical/prognostic accident and incident data that is available from the Aviation Safety Information Analysis and Sharing (ASIAS) System to determine the causal factors of system/component failures and/or malfunctions in U.S. commercial aviation accidents and incidents.

Ductile Crack Initiation Criterion with Mismatched Weld Joints Under Dynamic Loading Conditions.

PubMed

An, Gyubaek; Jeong, Se-Min; Park, Jeongung

2018-03-01

Brittle failure of high toughness steel structures tends to occur after ductile crack initiation/propagation. Damages to steel structures were reported in the Hanshin Great Earthquake. Several brittle failures were observed in beam-to-column connection zones with geometrical discontinuity. It is widely known that triaxial stresses accelerate the ductile fracture of steels. The study examined the effects of geometrical heterogeneity and strength mismatches (both of which elevate plastic constraints due to heterogeneous plastic straining) and loading rate on critical conditions initiating ductile fracture. This involved applying the two-parameter criterion (involving equivalent plastic strain and stress triaxiality) to estimate ductile cracking for strength mismatched specimens under static and dynamic tensile loading conditions. Ductile crack initiation testing was conducted under static and dynamic loading conditions using circumferentially notched specimens (Charpy type) with/without strength mismatches. The results indicated that the condition for ductile crack initiation using the two parameter criterion was a transferable criterion to evaluate ductile crack initiation independent of the existence of strength mismatches and loading rates.

The Measurement Of Total Joint Loosening By X-Ray Photogrammetry

NASA Astrophysics Data System (ADS)

Lippert, Frederick G.; Veress, Sandor A.; Tiwari, Rama S.; Harrington, Richard M.

1980-07-01

Failure of total joint replacement due to loosening of the composents either between the implant and cement or between the cement and bone is emerging as a late complication with an incidence as high as 20 percent. Loosening may not only cause pain but progressive loss of support for the prosthesis with eventual structural failure. Early diagnosis is important so that revision may be carried when deterioration or pain occurs. No method is currently available which clearly establishes loosening at an early stage except surgical exploration. We have devised a method based on our in vivo photogrammetry studies of patellar tracking patterns using metallic markers placed in bone near both components of the total joint. Stereo x-rays taken with the joint loaded and unloaded are measured for relative motion between the implant and the metallic markers. Laboratory studies using prosthetic hip components mounted in plastic bone have revealed the ability of this method to detect pistoning movements as small as 80 microns. These findings were confirmed by physical measurements.

Design of High Altitude Long Endurance UAV: Structural Analysis of Composite Wing using Finite Element Method

NASA Astrophysics Data System (ADS)

Kholish Rumayshah, Khodijah; Prayoga, Aditya; Mochammad Agoes Moelyadi, Ing., Dr.

2018-04-01

Research on a High Altitude Long Endurance (HALE) Unmanned Aerial Vehicle (UAV) is currently being conducted at Bandung Institute of Technology (ITB). Previously, the 1st generation of HALE UAV ITB used balsa wood for most of its structure. Flight test gave the result of broken wings due to extreme side-wind that causes large bending to its high aspect ratio wing. This paper conducted a study on designing the 2nd generation of HALE UAV ITB which used composite materials in order to substitute balsa wood at some critical parts of the wing’s structure. Finite element software ABAQUS/CAE is used to predict the stress and deformation that occurred. Tsai-Wu and Von-Mises failure criteria were applied to check whether the structure failed or not. The initial configuration gave the results that the structure experienced material failure. A second iteration was done by proposing a new configuration and it was proven safe against the load given.

Increased anion gap metabolic acidosis as a result of 5-oxoproline (pyroglutamic acid): a role for acetaminophen.

PubMed

Fenves, Andrew Z; Kirkpatrick, Haskell M; Patel, Viralkumar V; Sweetman, Lawrence; Emmett, Michael

2006-05-01

The endogenous organic acid metabolic acidoses that occur commonly in adults include lactic acidosis; ketoacidosis; acidosis that results from the ingestion of toxic substances such as methanol, ethylene glycol, or paraldehyde; and a component of the acidosis of kidney failure. Another rare but underdiagnosed cause of severe, high anion gap metabolic acidosis in adults is that due to accumulation of 5-oxoproline (pyroglutamic acid). Reported are four patients with this syndrome, and reviewed are 18 adult patients who were reported previously in the literature. Twenty-one patients had major exposure to acetaminophen (one only acute exposure). Eighteen (82%) of the 22 patients were women. Most of the patients were malnourished as a result of multiple medical comorbidities, and most had some degree of kidney dysfunction or overt failure. The chronic ingestion of acetaminophen, especially by malnourished women, may generate high anion gap metabolic acidosis. This undoubtedly is an underdiagnosed condition because measurements of serum and/or urinary 5-oxoproline levels are not readily available.

Molecular dynamics simulation analysis of the effect of T790M mutation on epidermal growth factor receptor protein architecture in non-small cell lung carcinoma.

PubMed

Peng, Xiao-Nu; Wang, Jing; Zhang, Wei

2017-08-01

Non-small cell lung cancer etiology and its treatment failure are due to epidermal growth factor receptor (EGFR) kinase domain mutations at amino acid position 790. The mutational change from threonine to methionine at position 790 (T790M) is responsible for tyrosine kinase inhibition failure. Using molecular dynamic simulation, the present study investigated the architectural changes occurring at the atomic scale. The 50-nsec runs using a GROMOS force field for wild-type and mutant EGFR's kinase domains were investigated for contrasting variations using Gromacs inbuilt tools. The adenosine triphosphate binding domain and the active site of EGFR were studied extensively in order to understand the structural changes. All the parameters investigated in the present study revealed considerable changes in the studied structures, and the knowledge gained from this may be used to develop novel kinase inhibitors that will be effective irrespective of the structural alterations in kinase domain.

Reliability and Qualification of Hardware to Enhance the Mission Assurance of JPL/NASA Projects

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni

2010-01-01

Packaging Qualification and Verification (PQV) and life testing of advanced electronic packaging, mechanical assemblies (motors/actuators), and interconnect technologies (flip-chip), platinum temperature thermometer attachment processes, and various other types of hardware for Mars Exploration Rover (MER)/Mars Science Laboratory (MSL), and JUNO flight projects was performed to enhance the mission assurance. The qualification of hardware under extreme cold to hot temperatures was performed with reference to various project requirements. The flight like packages, assemblies, test coupons, and subassemblies were selected for the study to survive three times the total number of expected temperature cycles resulting from all environmental and operational exposures occurring over the life of the flight hardware including all relevant manufacturing, ground operations, and mission phases. Qualification/life testing was performed by subjecting flight-like qualification hardware to the environmental temperature extremes and assessing any structural failures, mechanical failures or degradation in electrical performance due to either overstress or thermal cycle fatigue. Experimental flight qualification test results will be described in this presentation.

Investigating an API for resilient exascale computing.

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

Stearley, Jon R.; Tomkins, James; VanDyke, John P.

2013-05-01

Increased HPC capability comes with increased complexity, part counts, and fault occurrences. In- creasing the resilience of systems and applications to faults is a critical requirement facing the viability of exascale systems, as the overhead of traditional checkpoint/restart is projected to outweigh its bene ts due to fault rates outpacing I/O bandwidths. As faults occur and propagate throughout hardware and software layers, pervasive noti cation and handling mechanisms are necessary. This report describes an initial investigation of fault types and programming interfaces to mitigate them. Proof-of-concept APIs are presented for the frequent and important cases of memory errors and nodemore » failures, and a strategy proposed for lesystem failures. These involve changes to the operating system, runtime, I/O library, and application layers. While a single API for fault handling among hardware and OS and application system-wide remains elusive, the e ort increased our understanding of both the mountainous challenges and the promising trailheads. 3« less

Effect of the amount of Na2SO4 on the high temperature corrosion of Udimet-700

NASA Technical Reports Server (NTRS)

Misra, A. K.; Kohl, F. J.

1983-01-01

The corrosion of Udimet-700, coated with different doses of Na2SO4, was studied in an isothermal thermogravimetric test in the temperature range 900 to 950 C. The weight gain curve is characterized by five distinct stages: an initial period of linear corrosion; an induction period; a period of accelerated corrosion; a period of decelerating corrosion; and a period of parabolic oxidation. The time required for the failure of the alloy increases with an increase in the amount of Na2SO4, reaches a peak and then decreases with further increase in the amount of Na2SO4. For low and intermediate doses (0.3 to 2.0 mg/sq cm), the catastrophic failure of the material occurs by the formation of Na2MoO4 and interaction of the liquid Na2MoO4 with the alloy. For heavy doses, the degradation of the material is due to the formation of large amounts of sulfides.

Slow softening of Kanzi apples (Malus×domestica L.) is associated with preservation of pectin integrity in middle lamella.

PubMed

Gwanpua, Sunny George; Verlinden, Bert E; Hertog, Maarten L A T M; Nicolai, Bart M; Hendrickx, Marc; Geeraerd, Annemie

2016-11-15

Kanzi is a recently developed apple cultivar that has an extremely low ethylene production, and maintains its crispiness during ripening. To identify key determinants of the slow softening behaviour of Kanzi apples, a comparative analysis of pectin biochemistry and tissue fracture pattern during different ripening stages of Kanzi apples was performed against Golden Delicious, a rapid softening cultivar. While substantial pectin depolymerisation and solubilisation was observed during softening in Golden Delicious apples, no depolymerisation or increased solubilisation was observed in Kanzi apples. Moreover, tissue failure during ripening was mainly by cell breakage in Kanzi apples and, in contrast, by cell separation in Golden Delicious apples. Kanzi apples had lower activity of beta-galactosidase, with no decline in the extent of branching of the pectin chain. A sudden decrease in firmness observed during senescence in Kanzi apples was not due to middle lamella dissolution, as tissue failure still occurred by cell breakage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanism of electromigration failure in Damascene processed copper interconnects

NASA Astrophysics Data System (ADS)

Michael, Nancy Lyn

2002-11-01

A major unresolved issue in Cu interconnect reliability is the interface role in the failure mechanism of real structures. The present study investigates failure in single-level damascene Cu interconnects with variations in interface condition, passivation and barrier, and linewidth. In the first phase, accelerated electromigration testing of 0.25mum Cu interconnects capped with SiN or SiCN, shows that lifetime and failure mode vary with capping layer. The first mode, seen primarily in SiN samples, is characterized by gradual resistance increase and extensive interface damage, believed to result from failure led by interface electromigration. The competing failure mode, found in SiCN capped samples, is characterized by abrupt resistance increase and localized voiding. The second phase fixes SiCN as the capping material and varies barrier material and line width. The three barrier materials, Ta, TaN, and Ta/TaN, produce similar lifetime statistics and failure is abrupt. Line width, however, does have a strong influence on failure time. The line width/grain size ratio ranged from 0.53 to 2.2 but does not correlate with mean time to failure (MTF). The strong dependence on interface fraction, combined with the conclusion from phase one that interface electromigration is not rate controlling, suggests another mechanism related to the interface is a controlling factor. The possibility that contamination and defects at the interface are key to this failure mode was investigated using electro-thermal fatigue (ETF). In ETF, where lines are simultaneously subjected to thermal cycling and constant current, damage caused by thermal stress is accelerated. Tests reveal that in 80 nm lines, transient failure occurs at times far below MTF in electromigration tests at higher temperatures. Failure found in ETF is clearly a result of damage growth due to thermal/mechanical stress rather than electromigration. At the stress levels created by the moderate ETF test conditions, the only place voids are likely to nucleate and grow is at pre-existing defects and impurities. In narrower lines, where smaller voids can cause catastrophic damage, defects have a greater effect on MTF. Results from this investigation suggest that impurities and defects in the Cu and at the interface, must be carefully controlled to make reliable narrow Cu interconnects.

[Acute renal failure due to obstructive ureteral stone associated with norovirus gastroenteritis in an infant with congenital solitary kidney].

PubMed

Kato, Taiki; Hamano, Atsushi; Kawamura, Hideki

2014-10-01

We report a 35 month-old boy with acute renal failure caused by an obstructive ureteral stone associated with norovirus gastroenteritis. He visited his family physician because of fever, abdominal pain and vomiting. He was diagnosed as acute gastroenteritis. The symptoms relieved once, but abdominal pain and vomiting recurred two days after the visit and the volume of urine decreased. He was diagnosed as norovirus gastoenteritis and acute renal failure which was unresponsive to fluid replacement. Ultrasound study of the abdomen showed a solitary kidney with mild hydronephrosis. He was then admitted to our hospital. He was finally diagnosed as acute postrenal failure due to obstructive ureteral stone with left solitary kidney by abdominal computer tomography (CT). We performed transurethral catheterization immediately. The creatinine and blood urea nitrogen returned to normal level in 2 days. The CT performed on the 28th day post operation showed disappearance of the stone after uric alkalization. Recently, some cases of postrenal failure due to bilateral obstructive ureteral stones, mainly ammonium acid urate stones, associated with viral gastroenteritis were reported. As clinical features, they are common in boys three years or younger after an episode of rotavirus gastroenteritis with high uric acid concentration. By far, the most common cause of acute renal failure in patients with severe gastroenteritis is prerenal failure resulting from hypovolemia. But postrenal cause due to bilateral obstructive stones should be taken in a consideration.

Computational hydraulics of a cascade of experimental-scale landside dam failures

NASA Astrophysics Data System (ADS)

Wright, N.; Guan, M.

2015-12-01

Abstract: Landslide dams typically comprise unconsolidated and poorly sorted material, and are vulnerable to rapid failure and breaching, particularly in mountainous areas during high intense rainfalls. A large flash flood with high-concentrated sediment can be formed in a short period, and the magnitude is likely to be amplified along the flow direction due to the inclusion of a large amount of sediment. This can result in significant and sudden flood risk downstream for human life and property. Numerous field evidence has indicated the various risks of landslide dam failures. In general, cascading landslide dams can be formed along the sloping channel due to the randomness and unpredictability of landslides, which complexes the hydraulics of landslide dam failures. The failure process of a single dam and subsequent floods has attracted attention in multidisciplinary studies. However, the dynamic failure process of cascading landslide dams has been poorly understood. From a viewpoint of simulation, this study evaluates the formation and development of rapid sediment-charged floods due to cascading failure of landslide dams through detailed hydro-morphodynamic modelling. The model used is based on shallow water theory and it has been successful in predicting the flow and morphological process during sudden dam-break, as well as full and partial dyke-breach. Various experimental-scale scenarios are modelled, including: (1) failure of a single full dam in a sloping channel, (2) failure of two dams in a sloping channel, (3) failure of multiple landslide dams (four) in a sloping channel. For each scenario, different failure modes (sudden/gradual) and bed boundary (fixed /mobile) are assumed and simulated. The study systematically explores the tempo-spatial evolution of landslide-induced floods (discharge, flow velocity, and flow concentration) and geomorphic properties along the sloping channel. The effects of in-channel erosion and flow-driven sediment from dams on the development of flood process are investigated. The results improve the understanding of the formation and development mechanism of flash floods due to cascading landslide dam failures. The findings are beneficial for downstream flood risk assessment and developing control strategies for landslide-induced floods.

A huge bladder calculus causing acute renal failure.

PubMed

Komeya, Mitsuru; Sahoda, Tamami; Sugiura, Shinpei; Sawada, Takuto; Kitami, Kazuo

2013-02-01

A 81-year-old male was referred to our emergency outpatient unit due to acute renal failure. The level of serum creatinine was 276 μmol/l. A CT scan showed bilateral hydronephroureter, large bladder stone (7 cm × 6 cm × 6 cm) and bladder wall thickness. He was diagnosed as post renal failure due to bilateral hydronephroureter. Large bladder stone is thought to be the cause of bilateral hydronephroureter and renal failure. To improve renal failure, we performed open cystolithotomy and urethral catheterization. Three days after the surgery, the level of serum creatinine decreased to 224 μmol/l. He was discharged from our hospital with uneventful course. Bladder calculus is thought to be a rare cause of renal failure. We summarize the characteristics of bladder calculus causing renal failure. We should keep that long-term pyuria and urinary symptom, and repeated urinary tract infection can cause huge bladder calculus and renal failure in mind.

The Loss of GSTM1 Associates with Kidney Failure and Heart Failure.

PubMed

Tin, Adrienne; Scharpf, Robert; Estrella, Michelle M; Yu, Bing; Grove, Megan L; Chang, Patricia P; Matsushita, Kunihiro; Köttgen, Anna; Arking, Dan E; Boerwinkle, Eric; Le, Thu H; Coresh, Josef; Grams, Morgan E

2017-11-01

Glutathione S-transferase mu 1 ( GSTM1) encodes an enzyme that catalyzes the conjugation of electrophilic compounds with glutathione to facilitate their degradation or excretion. The loss of one or both copies of GSTM1 is common in many populations and has been associated with CKD progression. With the hypothesis that the loss of GSTM1 is also associated with incident kidney failure and heart failure, we estimated GSTM1 copy number using exome sequencing reads in the Atherosclerosis Risk in Communities (ARIC) Study, a community-based prospective cohort of white and black participants. Overall, 51.2% and 39.8% of white participants and 25.6% and 48.5% of black participants had zero or one copy of GSTM1 , respectively. Over a median follow-up of 24.6 years, 256 kidney failure events occurred in 5715 participants without prevalent kidney failure, and 1028 heart failure events occurred in 5368 participants without prevalent heart failure. In analysis adjusted for demographics, diabetes, and hypertension, having zero or one copy of GSTM1 associated with higher risk of kidney failure and heart failure (adjusted hazard ratio [95% confidence interval] for zero or one versus two copies of GSTM1 : kidney failure, 1.66 [1.27 to 2.17]; heart failure, 1.16 [1.04 to 1.29]). Risk did not differ significantly between participants with zero and one copy of GSTM1 ( P >0.10). In summary, the loss of GSTM1 was significantly associated with incident kidney and heart failure, independent of traditional risk factors. These results suggest GSTM1 function is a potential treatment target for the prevention of kidney and heart failure. Copyright © 2017 by the American Society of Nephrology.

Radiotherapy for esthesioneuroblastoma: is elective nodal irradiation warranted in the multimodality treatment approach?

PubMed

Noh, O Kyu; Lee, Sang-wook; Yoon, Sang Min; Kim, Sung Bae; Kim, Sang Yoon; Kim, Chang Jin; Jo, Kyung Ja; Choi, Eun Kyung; Song, Si Yeol; Kim, Jong Hoon; Ahn, Seung Do

2011-02-01

The role of elective nodal irradiation (ENI) in radiotherapy for esthesioneuroblastoma (ENB) has not been clearly defined. We analyzed treatment outcomes of patients with ENB and the frequency of cervical nodal failure in the absence of ENI. Between August 1996 and December 2007, we consulted with 19 patients with ENB regarding radiotherapy. Initial treatment consisted of surgery alone in 2 patients; surgery and postoperative radiotherapy in 4; surgery and adjuvant chemotherapy in 1; surgery, postoperative radiotherapy, and chemotherapy in 3; and chemotherapy followed by radiotherapy or concurrent chemoradiotherapy in 5. Five patients did not receive planned radiotherapy because of disease progression. Including 2 patients who received salvage radiotherapy, 14 patients were treated with radiotherapy. Elective nodal irradiation was performed in 4 patients with high-risk factors, including 3 with cervical lymph node metastasis at presentation. Fourteen patients were analyzable, with a median follow-up of 27 months (range, 7-64 months). The overall 3-year survival rate was 73.4%. Local failure occurred in 3 patients (21.4%), regional cervical failure in 3 (21.4%), and distant failure in 2 (14.3%). No cervical nodal failure occurred in patients treated with combined systemic chemotherapy regardless of ENI. Three cervical failures occurred in the 4 patients treated with ENI or neck dissection (75%), none of whom received systemic chemotherapy. ENI during radiotherapy for ENB seems to play a limited role in preventing cervical nodal failure. Omitting ENI may be an option if patients are treated with a combination of radiotherapy and chemotherapy. Copyright © 2011 Elsevier Inc. All rights reserved.

A case study of a real-time evaluation of the risk of disease transmission associated with a failure to follow recommended sterilization procedures

PubMed Central

2014-01-01

Background Failures to follow recommendations for reprocessing of surgical instruments may place patients at risk for exposure to pathogenic microorganisms. When such failures occur, medical facilities often face considerable uncertainty and challenges in assessing the actual risks of disease transmission. Methods In 2011, staff at an Ohio hospital determined that surgical instruments inside a Steriset Container had inadvertently been autoclaved on a gravity cycle rather than on the recommended pre-vacuum cycle, potentially exposing 72 patients who underwent surgery with the instruments to risk of infection. To provide an assessment of the level of risk, we tested the effectiveness of the machine washer/disinfector step and of the sterilization process inside the Steriset Container on the gravity cycle for killing of Geobacillus stearothermophilus spores, Clostridium difficile spores, and methicillin-resistant Staphylococcus aureus (MRSA). Based on the test results, the risk of transmission of MRSA by the instruments was calculated and the risk of transmission of hepatitis B virus was estimated. Results The machine washer/disinfector consistently reduced MRSA recovery by a factor of 1:100,000. The sterilization process inside the Steriset Container consistently reduced MRSA concentrations by a factor of >1:10,000,000 and killed 105C. difficile spores and 105G. stearothermophilus spores. The risk of MRSA transmission due to the incident was calculated to be 1 in 100 trillion. Conclusions The risk for transmission of infection due to the failure to follow recommended sterilization processes was negligible based upon complete killing of G. stearothermophilus biological indicator spores, C. difficile spores, and MRSA under conditions that replicated the incident where proper procedures were not followed. Such real-time assessments of the risks associated with specific incidents may provide evidence-based information that can be used to inform decisions regarding disclosure of the incident to patients. PMID:24447336

A case study of a real-time evaluation of the risk of disease transmission associated with a failure to follow recommended sterilization procedures.

PubMed

Donskey, Curtis J; Yowler, Marian; Falck-Ytter, Yngve; Kundrapu, Sirisha; Salata, Robert A; Rutala, William A

2014-01-21

Failures to follow recommendations for reprocessing of surgical instruments may place patients at risk for exposure to pathogenic microorganisms. When such failures occur, medical facilities often face considerable uncertainty and challenges in assessing the actual risks of disease transmission. In 2011, staff at an Ohio hospital determined that surgical instruments inside a Steriset Container had inadvertently been autoclaved on a gravity cycle rather than on the recommended pre-vacuum cycle, potentially exposing 72 patients who underwent surgery with the instruments to risk of infection. To provide an assessment of the level of risk, we tested the effectiveness of the machine washer/disinfector step and of the sterilization process inside the Steriset Container on the gravity cycle for killing of Geobacillus stearothermophilus spores, Clostridium difficile spores, and methicillin-resistant Staphylococcus aureus (MRSA). Based on the test results, the risk of transmission of MRSA by the instruments was calculated and the risk of transmission of hepatitis B virus was estimated. The machine washer/disinfector consistently reduced MRSA recovery by a factor of 1:100,000. The sterilization process inside the Steriset Container consistently reduced MRSA concentrations by a factor of >1:10,000,000 and killed 105C. difficile spores and 105G. stearothermophilus spores. The risk of MRSA transmission due to the incident was calculated to be 1 in 100 trillion. The risk for transmission of infection due to the failure to follow recommended sterilization processes was negligible based upon complete killing of G. stearothermophilus biological indicator spores, C. difficile spores, and MRSA under conditions that replicated the incident where proper procedures were not followed. Such real-time assessments of the risks associated with specific incidents may provide evidence-based information that can be used to inform decisions regarding disclosure of the incident to patients.

Multi-physics modeling of multifunctional composite materials for damage detection

NASA Astrophysics Data System (ADS)

Sujidkul, Thanyawalai

This study presents a modeling of multifunction composite materials for damage detection with its verification and validation to mechanical behavior predictions of Carbon Fibre Reinforced Polymer composites (CFRPs), CFRPs laminated composites, and woven SiC/SiC matrix composites that are subjected to fracture damage. Advantages of those materials are low cost, low density, high strength-to-weight ratio, and comparable specific tensile properties, the special of SiC/SiC is good environmental stability at high temperature. Resulting in, the composite has been used for many important structures such as helicopter rotors, aerojet engines, gas turbines, hot control surfaces, sporting goods, and windmill blades. Damage or material defect detection in a mechanical component can provide vital information for the prediction of remaining useful life, which will result in the prevention of catastrophic failures. Thus the understanding of the mechanical behavior have been challenge to the prevent damage and failure of composites in different scales. The damage detection methods in composites have been investigated widely in recent years. Non-destructive techniques are the traditional methods to detect the damage such as X-ray, acoustic emission and thermography. However, due to the invisible damage in composite can be occurred, to prevent the failure in composites. The developments of damage detection methods have been considered. Due to carbon fibers are conductive materials, in resulting CFRPs can be self-sensing to detect damage. As is well known, the electrical resistance has been shown to be a sensitive measure of internal damage, and also this work study in thermal resistance can detect damage in composites. However, there is a few number of different micromechanical modeling schemes has been proposed in the published literature for various types of composites. This works will provide with a numerical, analytical, and theoretical failure models in different damages to predict the mechanical damage behavior with electrical properties and thermal properties.

Complex ruptures during hydraulic fracturing of the Marcellus Shale

NASA Astrophysics Data System (ADS)

Viegas, G. F.; Urbancic, T.; Bosman, K.; Baig, A. M.

2016-12-01

Complex rupture patterns were observed on several M0+ events recorded during a hydraulic stimulation of the Marcellus shale. Although M>0 events associated with hydraulic fracturing have now been commonly recorded and may cause concern in terms of public and infrastructure safety, the vast majority of these events are smaller than M3 and are not felt at the surface. We investigate the rupture characteristics of one such multi-rupture event with 3 sub-events, by examining the failure dynamics of the overall fracture itself and of each individual sub-event, and the growth of the overall fracture from rupture initiation to arrest. This analysis is only possible due to the wide frequency range of the seismic monitoring system put in place which spanned from 0.1 Hz to 1000 Hz. The monitoring system consists of: high-frequency sensor-arrays of geophones deployed downhole close to the reservoir and thus to the rupture initiation point; and low to intermediate frequency accelerometers and geophones deployed at intermediate and shallow depths, allowing for the investigation of overall rupture characteristics. We aim to gain an understanding of the role of asperities, fracture roughness, and fluids on the different aspects of the rupture processes and of the failure mechanisms (shearing versus tensile dominance of behavior) associated with these complex events. Our results show that the overall event is characterized by the failure of multiple asperities and the distance between the 3 sub-events is less than 20 m. We observe decreasing stress drop and increasing Mw over time for the successive sub-events which suggest decreasing frictional resistance due to the presence of fluids over an increasingly large rupture surface akin to increased slip over a larger and less resistant contact area such as an asperity. The overall failure shows a dominant shearing mode mechanism whereas the sub-events failures show strong tensile components. The ruptures of the 1st and 2nd sub-events are indicative of shear-compaction of an asperity and the one of the 3rd sub-event is suggestive of a rupture riding over several surface patches. Additional analysis of other complex events will improve the characterization of the rupture processes of these larger-magnitude events and allow for the assessment of conditions under which the failures occur.

Second allogeneic hematopoietic cell transplantation for Patients with Fanconi anemia and Bone Marrow Failure

PubMed Central

Ayas, Mouhab; Eapen, Mary; Le-Rademacher, Jennifer; Carreras, Jeanette; Abdel-Azim, Hisham; Alter, Blanche P.; Anderlini, Paolo; Battiwalla, Minoo; Bierings, Marc; Buchbinder, David K.; Bonfim, Carmem; Camitta, Bruce M.; Fasth, Anders L.; Gale, Robert Peter; Lee, Michelle A.; Lund, Troy C.; Myers, Kasiani C.; Olsson, Richard F.; Page, Kristin M.; Prestidge, Tim D.; Radhi, Mohamed; Shah, Ami J.; Schultz, Kirk R.; Wirk, Baldeep; Wagner, John E.; Deeg, H. Joachim

2015-01-01

Second allogeneic hematopoietic cell transplantation (HCT) is the only salvage option for those for develop graft failure after their first HCT. Data on outcomes after second HCT in Fanconi anemia (FA) are scarce. We report outcomes after second allogeneic HCT for FA (n=81). The indication for second HCT was graft failure after the first HCT. Transplants occurred between 1990 and 2012. The timing of second transplantation predicted subsequent graft failure and survival. Graft failure was high when the second transplant occurred less than 3 months from the first. The 3-month probability of graft failure was 69% when the interval between first and second transplant was less than 3 months compared to 23% when the interval was longer (p<0.001). Consequently, survival rates were substantially lower when the interval between first and second transplant was less than 3 months, 23% at 1-year compared to 58%, when the interval was longer (p=0.001). The corresponding 5-year probabilities of survival were 16% and 45%, respectively (p=0.006). Taken together, these data suggest that fewer than half of FA patients undergoing a second HCT for graft failure are long-term survivors. There is an urgent need to develop strategies to lower graft failure after first HCT. PMID:26116087

Submarine landslides of San Pedro Escarpment, southwest of Long Beach, California

USGS Publications Warehouse

Bohannon, R.G.; Gardner, J.V.

2004-01-01

The coastal infrastructure of the southern greater Los Angeles metropolitan area would be profoundly affected by a large tsunami. Submarine slope failures and active faults, either of which could have generated a tsunami, are known on the shelf and slope near Long Beach. Large slope failures are present on the San Pedro Escarpment and on the basin slope adjacent to the San Pedro shelf. The southeastern part of the escarpment has had a long history of slope failure. The most recent failure, the Palos Verdes slide, is over 4.5 km long, has been dated as 7500 years old, and involved over 0.34 km 3 of material, which now litters the adjacent basin floor. Other, smaller, deposits from nearby failures are also present, as are buried wedges of debris that indicate slope failures have occurred locally throughout the Holocene and much of the late Pleistocene. Slope failures have occurred in response to continual Quaternary uplift of the Palos Verdes anticlinorium. The Palos Verdes slide could potentially have generated a failure-related tsunami with an amplitude in the range of 8-12 m because it apparently failed catastrophically, started in shallow water, evolved on low-drag bedding planes, had a long slide path, and involved high-strength lithified material. ?? 2003 Elsevier B.V. All rights reserved.

Modes of failure of Osteonics constrained tripolar implants: a retrospective analysis of forty-three failed implants.

PubMed

Guyen, Olivier; Lewallen, David G; Cabanela, Miguel E

2008-07-01

The Osteonics constrained tripolar implant has been one of the most commonly used options to manage recurrent instability after total hip arthroplasty. Mechanical failures were expected and have been reported. The purpose of this retrospective review was to identify the observed modes of failure of this device. Forty-three failed Osteonics constrained tripolar implants were revised at our institution between September 1997 and April 2005. All revisions related to the constrained acetabular component only were considered as failures. All of the devices had been inserted for recurrent or intraoperative instability during revision procedures. Seven different methods of implantation were used. Operative reports and radiographs were reviewed to identify the modes of failure. The average time to failure of the forty-three implants was 28.4 months. A total of five modes of failure were observed: failure at the bone-implant interface (type I), which occurred in eleven hips; failure at the mechanisms holding the constrained liner to the metal shell (type II), in six hips; failure of the retaining mechanism of the bipolar component (type III), in ten hips; dislocation of the prosthetic head at the inner bearing of the bipolar component (type IV), in three hips; and infection (type V), in twelve hips. The mode of failure remained unknown in one hip that had been revised at another institution. The Osteonics constrained tripolar total hip arthroplasty implant is a complex device involving many parts. We showed that failure of this device can occur at most of its interfaces. It would therefore appear logical to limit its application to salvage situations.

Ballistic Impact of Braided Composites with a Soft Projectile

NASA Technical Reports Server (NTRS)

Roberts, Gary D.; Pereira, J. Michael; Revilock, Duane M., Jr.; Binienda, Wieslaw K.; Xie, Ming; Braley, Mike

2002-01-01

Impact tests using a soft gelatin projectile were performed to identify failure modes that occur at high strain energy density during impact loading. Failure modes were identified for aluminum plates and for composites plates and half-rings made from triaxial carbon fiber braid having a 0/+/- 60deg architecture. For aluminum plates, a large hole formed as a result of crack propagation from the initiation site at the center of the plate. For composite plates, fiber tensile failure occurred in the back ply at the center of the plate. Cracks then propagated from this site along the +/-60deg fiber directions until triangular flaps opened to form a hole. For composite half-rings fabricated with 0deg fibers aligned circumferentially, fiber tensile failure also occurred in the back ply. Cracks first propagated from this site perpendicular the 0deg fibers. The cracks then turned to follow the +/-60deg fibers and 0deg fibers until rectangular flaps opened to form a hole. Damage in the composites was localized near the impact site, while cracks in the aluminum extended to the boundaries.

[Comorbidities of heart failure: sleep apnea].

PubMed

Woehrle, H; Oldenburg, O; Stadler, S; Arzt, M

2018-05-01

Since sleep apnea often occurs in heart failure, physicians regularly need to decide whether further diagnostic procedures and/or treatment are required. Which types of sleep apnea occur in heart failure patients? When is treatment needed? Which treatments and treatment goals are appropriate? Clinical trials and guidelines as well as their implementation in clinical practice are discussed. At least 40% of patients with heart failure, both with reduced and preserved left ventricular ejection fraction (HFrEF and HFpEF, respectively), suffer from relevant sleep apnea. In heart failure patients both obstructive and central sleep apnea are associated with increased mortality. In HFrEF as well as in HFpEF patients with obstructive sleep apnea, treatment with continuous positive airway pressure (CPAP) achieves symptomatic and functional improvements. In patients with HFpEF, positive airway pressure treatment of central sleep apnea may be beneficial. In patients with HFrEF and left ventricular ejection fraction ≤45%, adaptive servoventilation is contraindicated. Sleep apnea is highly prevalent in heart failure patients and its treatment in specific patient groups can improve symptoms and functional outcomes. Thus, testing for sleep apnea is recommended.

Injury pattern as an indication of seat belt failure in ejected vehicle occupants.

PubMed

Freeman, Michael D; Eriksson, Anders; Leith, Wendy

2014-09-01

Prior authors have suggested that when occupant ejection occurs in association with a seat belt failure, entanglement of the outboard upper extremity (OUE) with the retracting shoulder belt will invariably occur, leaving injury pattern evidence of belt use. In the present investigation, the authors assessed this theory using data accessed from the NASS-CDS for ejected front seat occupants of passenger vehicles. Logistic regression models were used to assess the associations between seat belt failure status and injuries. Injury types associated with seat belt failure were significant OUE and head injuries (OR = 3.87, [95% CI 1.2, 13.0] and 3.1, [95% CI 1.0, 9.7], respectively). The two injury types were found to be a predictor of seat belt use and subsequent failure only if combined with a high (≥0.8) precrash probability of belt use. The injury pattern associated with a seat belt failure-related ejection has limited use in the forensic investigation of crash-related ejections. © 2014 American Academy of Forensic Sciences.

Passive seismic monitoring of natural and induced earthquakes: case studies, future directions and socio-economic relevance

USGS Publications Warehouse

Bohnhoff, Marco; Dresen, Georg; Ellsworth, William L.; Ito, Hisao; Cloetingh, Sierd; Negendank, Jörg

2010-01-01

An important discovery in crustal mechanics has been that the Earth’s crust is commonly stressed close to failure, even in tectonically quiet areas. As a result, small natural or man-made perturbations to the local stress field may trigger earthquakes. To understand these processes, Passive Seismic Monitoring (PSM) with seismometer arrays is a widely used technique that has been successfully applied to study seismicity at different magnitude levels ranging from acoustic emissions generated in the laboratory under controlled conditions, to seismicity induced by hydraulic stimulations in geological reservoirs, and up to great earthquakes occurring along plate boundaries. In all these environments the appropriate deployment of seismic sensors, i.e., directly on the rock sample, at the earth’s surface or in boreholes close to the seismic sources allows for the detection and location of brittle failure processes at sufficiently low magnitude-detection threshold and with adequate spatial resolution for further analysis. One principal aim is to develop an improved understanding of the physical processes occurring at the seismic source and their relationship to the host geologic environment. In this paper we review selected case studies and future directions of PSM efforts across a wide range of scales and environments. These include induced failure within small rock samples, hydrocarbon reservoirs, and natural seismicity at convergent and transform plate boundaries. Each example represents a milestone with regard to bridging the gap between laboratory-scale experiments under controlled boundary conditions and large-scale field studies. The common motivation for all studies is to refine the understanding of how earthquakes nucleate, how they proceed and how they interact in space and time. This is of special relevance at the larger end of the magnitude scale, i.e., for large devastating earthquakes due to their severe socio-economic impact.

Recovery free of heart failure after acute coronary syndrome and coronary revascularization.

PubMed

Falkenham, Alec; Saraswat, Manoj K; Wong, Chloe; Gawdat, Kareem; Myers, Tanya; Begum, Jahanara; Buth, Karen J; Haidl, Ian; Marshall, Jean; Légaré, Jean-Francois

2018-02-01

Previous studies have examined risk factors for the development of heart failure (HF) subsequent to acute coronary syndrome (ACS). Our study seeks to clarify the clinical variables that best characterize patients who remain free from HF after coronary artery bypass grafting (CABG) surgery for ACS to determine novel biological factors favouring freedom from HF in prospective translational studies. Nova Scotia residents (1995-2012) undergoing CABG within 3 weeks of ACS were included. The primary outcome was freedom from readmission to hospital due to HF. Descriptive statistics were generated, and a Cox proportional hazards model assessed outcome with adjustment for clinical characteristics. Of 11 936 Nova Scotians who underwent isolated CABG, 3264 (27%) had a recent ACS and were included. Deaths occurred in 210 (6%) of subjects prior to discharge. A total of 3054 patients were included in the long-term analysis. During follow-up, HF necessitating readmission occurred in 688 (21%) subjects with a hazard ratio of 12% at 2 years. The adjusted Cox model demonstrated significantly better freedom from HF for younger, male subjects without metabolic syndrome and no history of chronic obstructive pulmonary disease, renal insufficiency, atrial fibrillation, or HF. Our findings have outlined important clinical variables that predict freedom from HF. Furthermore, we have shown that 12% of patients undergoing CABG after ACS develop HF (2 years). Our findings support our next phase in which we plan to prospectively collect blood and tissue specimens from ACS patients undergoing CABG in order to determine novel biological mechanism(s) that favour resolution of post-ACS inflammation. © 2017 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

Experimental Study of Slabbing and Rockburst Induced by True-Triaxial Unloading and Local Dynamic Disturbance

NASA Astrophysics Data System (ADS)

Du, Kun; Tao, Ming; Li, Xi-bing; Zhou, Jian

2016-09-01

Slabbing/spalling and rockburst are unconventional types of failure of hard rocks under conditions of unloading and various dynamic loads in environments with high and complex initial stresses. In this study, the failure behaviors of different rock types (granite, red sandstone, and cement mortar) were investigated using a novel testing system coupled to true-triaxial static loads and local dynamic disturbances. An acoustic emission system and a high-speed camera were used to record the real-time fracturing processes. The true-triaxial unloading test results indicate that slabbing occurred in the granite and sandstone, whereas the cement mortar underwent shear failure. Under local dynamically disturbed loading, none of the specimens displayed obvious fracturing at low-amplitude local dynamic loading; however, the degree of rock failure increased as the local dynamic loading amplitude increased. The cement mortar displayed no failure during testing, showing a considerable load-carrying capacity after testing. The sandstone underwent a relatively stable fracturing process, whereas violent rockbursts occurred in the granite specimen. The fracturing process does not appear to depend on the direction of local dynamic loading, and the acoustic emission count rate during rock fragmentation shows that similar crack evolution occurred under the two test scenarios (true-triaxial unloading and local dynamically disturbed loading).

Reliability analysis of the F-8 digital fly-by-wire system

NASA Technical Reports Server (NTRS)

Brock, L. D.; Goodman, H. A.

1981-01-01

The F-8 Digital Fly-by-Wire (DFBW) flight test program intended to provide the technology for advanced control systems, giving aircraft enhanced performance and operational capability is addressed. A detailed analysis of the experimental system was performed to estimated the probabilities of two significant safety critical events: (1) loss of primary flight control function, causing reversion to the analog bypass system; and (2) loss of the aircraft due to failure of the electronic flight control system. The analysis covers appraisal of risks due to random equipment failure, generic faults in design of the system or its software, and induced failure due to external events. A unique diagrammatic technique was developed which details the combinatorial reliability equations for the entire system, promotes understanding of system failure characteristics, and identifies the most likely failure modes. The technique provides a systematic method of applying basic probability equations and is augmented by a computer program written in a modular fashion that duplicates the structure of these equations.

Aerodynamic Tests of a Full-scale TBF-1 Aileron Installation in the Langley 16-foot High-Speed Tunnel

NASA Technical Reports Server (NTRS)

Becker, John V; Korycinski, Peter F

1944-01-01

The failure of wing panels on a number of TBF-1 and TBM-1 airplanes in flight has prompted several investigations of the possible causes of failure. This report describes tests in the Langley 16-foot high-speed tunnel to determine whether these failures could be attributed to changes in the aerodynamic characteristics of the ailerons at high speeds. The tests were made of a 12-foot-span section including the tip and aileron of the right wing of a TBF-1 airplane. Hinge moments, control-link stresses due to aerodynamic buffeting, and fabric-deflection photographs were obtained at true airspeeds ranging from 110 to 365 miles per hour. The aileron hinge-moment coefficients were found to vary only slightly with airspeed in spite of the large fabric deflections that developed as the speed was increased. An analysis of these results indicated that the resultant hinge moment of the ailerons as installed in the airplane would tend to restore the ailerons to their neutral position for all the high-speed flight conditions covered in the tests. Serious aerodynamic buffeting occurred at up aileron angles of -10 degrees or greater because of stalling of the sharp projecting lip of the Frise aileron. The peak stresses set up in the aileron control linkages in the buffeting condition were as high as three times the mean stress. During the hinge-moment investigation, flutter of the test installation occurred at airspeeds of about 150 miles per hour. This flutter condition was investigated in some detail and slow-motion pictures were made of the motion of the wing tip and aileron. The flutter was found to involve simultaneous normal bending and chordwise oscillation of the wing and flapping of the aileron. The aileron motion appeared to be coupled with this flutter condition and was investigated in some detail and slow-motion pictures were made of the motion of the wing tip and aileron. The flutter was found to involve simultaneous normal bending and chordwise oscillation of the wing and flapping of the aileron. The aileron motion appeared to be coupled with the motion of the wing through the mass unbalance of the aileron in the normal-to-chord plane due to location of the hinge line 2.17 inches below the center of gravity of the aileron. Flutter did not occur when the installation was stiffened to prevent chordwise motion or when the bending frequency of the aileron system was appreciably higher than that of the wing as in the complete airplane installation.

Nemaline myopathy and heart failure: role of ivabradine; a case report.

PubMed

Sarullo, Filippo M; Vitale, Giuseppe; Di Franco, Antonino; Sarullo, Silvia; Salerno, Ylenia; Vassallo, Laura; Baviera, Emanuela Petrona; Marazia, Stefania; Mandalà, Giorgio; Lanza, Gaetano A

2015-01-19

Nemaline myopathy (NM) is a rare congenital myopathy characterized by muscle weakness, hypotonia and the presence in muscle fibers of inclusions known as nemaline bodies and a wide spectrum of clinical phenotypes, ranging from severe forms with neonatal onset to asymptomatic forms. The adult-onset form is heterogeneous in terms of clinical presentation and disease progression. Cardiac involvement occurs in the minority of cases and little is known about medical management in this subgroup of NM patients. We report a rare case of heart failure (HF) in a patient with adult-onset NM in whom ivabradine proved to be able to dramatically improve the clinical picture. We report a case of a 37-year-old man with adult-onset NM, presenting with weakness and hypotonia of the proximal limb muscles and shoulder girdle, severely limiting daily activities. He developed progressive HF over a period of 6 months while attending a rehabilitation program, with reduced left ventricular ejection fraction (LVEF = 20%), manifested by dyspnea and signs of systemic congestion. The patient was started HF therapy with enalapril, carvedilol, spironolactone and loop diuretics. Target HF doses of these drugs (including carvedilol) were not reached because of symptomatic hypotension causing a high resting heart rate (HR) ≥70 beats per minute (bpm). Further deterioration of the clinical picture occurred with several life-threatening arrhythmic episodes requiring external defibrillation. An implantable cardioverter defibrillator (ICD) was then implanted. Persistent high resting HR was successfully treated with ivabradine with HR lowering from 90 bpm to 55 bpm at 1 month follow up, LVEF rising to 50% at 3 month follow up and to 54% at 2,5 year follow up. To date no more hospitalizations for heart failure occurred. A single hospitalization due to aspiration pneumonia required insertion of a tracheostomy tube to protect airways from further aspiration. At present, the patient is attending a regular rehabilitation program with net improvement in neuromotor control and less limitations in daily activities. HF is a rare feature of NM, but it can negatively influence prognosis. Conventional HF therapy and/or heart transplant are the only reasonable strategy in these patients. Ivabradine is a useful, effective and safe drug for therapy in NM patients with HF and should be considered when resting HR remains high despite beta-blockers' full titration or beta-blockers' underdosing due to intolerance or side effects.

A Reliable Data Transmission Model for IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi Interference.

PubMed

Sahoo, Prasan Kumar; Pattanaik, Sudhir Ranjan; Wu, Shih-Lin

2017-06-07

The IEEE 802.15.4e standard proposes Medium Access Control (MAC) to support collision-free wireless channel access mechanisms for industrial, commercial and healthcare applications. However, unnecessary wastage of energy and bandwidth consumption occur due to inefficient backoff management and collisions. In this paper, a new channel access mechanism is designed for the buffer constraint sensor devices to reduce the packet drop rate, energy consumption and collisions. In order to avoid collision due to the hidden terminal problem, a new frame structure is designed for the data transmission. A new superframe structure is proposed to mitigate the problems due to WiFi and ZigBee interference. A modified superframe structure with a new retransmission opportunity for failure devices is proposed to reduce the collisions and retransmission delay with high reliability. Performance evaluation and validation of our scheme indicate that the packet drop rate, throughput, reliability, energy consumption and average delay of the nodes can be improved significantly.

The application of a piezo-resistive cardiorespiratory sensor system in an automobile safety belt.

PubMed

Hamdani, Syed Talha Ali; Fernando, Anura

2015-03-30

Respiratory and heart failure are conditions that can occur with little warning and may also be difficult to predict. Therefore continuous monitoring of these bio-signals is advantageous for ensuring human health. The car safety belt is mainly designed to secure the occupants of the vehicle in the event of an accident. In the current research a prototype safety belt is developed, which is used to acquire respiratory and heart signals, under laboratory conditions. The current safety belt is constructed using a copper ink based nonwoven material, which works based on the piezo-resistive effect due to the pressure exerted on the sensor as a result of expansion of the thorax/abdomen area of the body for respiration and due to the principle of ballistocardiography (BCG) in heart signal sensing. In this research, the development of a theoretical model to qualitatively describe the piezo-resistive material is also presented in order to predict the relative change in the resistance of the piezo-resistive material due to the pressure applied.

A Reliable Data Transmission Model for IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi Interference

PubMed Central

Sahoo, Prasan Kumar; Pattanaik, Sudhir Ranjan; Wu, Shih-Lin

2017-01-01

The IEEE 802.15.4e standard proposes Medium Access Control (MAC) to support collision-free wireless channel access mechanisms for industrial, commercial and healthcare applications. However, unnecessary wastage of energy and bandwidth consumption occur due to inefficient backoff management and collisions. In this paper, a new channel access mechanism is designed for the buffer constraint sensor devices to reduce the packet drop rate, energy consumption and collisions. In order to avoid collision due to the hidden terminal problem, a new frame structure is designed for the data transmission. A new superframe structure is proposed to mitigate the problems due to WiFi and ZigBee interference. A modified superframe structure with a new retransmission opportunity for failure devices is proposed to reduce the collisions and retransmission delay with high reliability. Performance evaluation and validation of our scheme indicate that the packet drop rate, throughput, reliability, energy consumption and average delay of the nodes can be improved significantly. PMID:28590434

In-Flight Calibration of the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory

NASA Technical Reports Server (NTRS)

Esposito, J. A.; Bertsch, D. L.; Chen, A. W.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.;

Apparatus for storing hydrogen isotopes

DOEpatents

McMullen, John W.; Wheeler, Michael G.; Cullingford, Hatice S.; Sherman, Robert H.

1985-01-01

An improved method and apparatus for storing isotopes of hydrogen (especially tritium) are provided. The hydrogen gas(es) is (are) stored as hydrides of material (for example uranium) within boreholes in a block of copper. The mass of the block is critically important to the operation, as is the selection of copper, because no cooling pipes are used. Because no cooling pipes are used, there can be no failure due to cooling pipes. And because copper is used instead of stainless steel, a significantly higher temperature can be reached before the eutectic formation of uranium with copper occurs, (the eutectic of uranium with the iron in stainless steel forming at a significantly lower temperature).

[Epidural aspergillosis secondary to lung aspergilloma despite long-term itraconazole treatment].

PubMed

Jeanrot, C; Guigui, P; Groussard, O; Deburge, A

2001-10-01

A 58-year-old man developed spinal cord compression at the T2-T3 level due to an Aspergillus epidural abscess. This presumably immunocompetent patient had been treated for two years by oral itraconazole (200 mg/day) for a lung aspergilloma that occurred seven years after removal of a lung adenocarcinoma. Surgical debridement was performed via a wide posterior approach associated with high-dose amphotericin B. Five months later, the patient's neurological deficit had not improved and the patient died from respiratory failure. Despite a long-term treatment with itraconazole, the infection spread locally from a lung aspergilloma to the epidural space.

Case Report of a Pressure Ulcer Occurring Over the Nasal Bridge Due to a Non-Invasive Ventilation Facial Mask.

PubMed

Rathore, Farooq A; Ahmad, Faria; Zahoor, Muhammad Umar U

2016-10-03

Non-invasive ventilation (NIV) is used in patients with respiratory failure, sleep apnoea, and dyspnoea related to pulmonary oedema. NIV is provided through a facial mask. Many complications of NIV facial masks have been reported, including the breakdown of facial skin. We report a case of an elderly male admitted with multiple co-morbidities. The facial mask was applied continuously for NIV, without any relief or formal monitoring of the underlying skin. It resulted in a Grade II pressure ulcer. We discuss the possible mechanism and offer advice for prevention of such device-related pressure ulcers.

Retention and application of Skylab experiment experiences to future programs

NASA Technical Reports Server (NTRS)

Milly, N.; Gillespie, V. G.

1974-01-01

Problems encountered on Skylab Experiments are listed in order that these experiences and associated recommendations might help to prevent similar problems on future programs. The criteria for selection of the data to be utilized was to identify the problem areas within the Skylab Program which would be of major significance with respect to future programs. Also, the problem had to be unique in that it would help identify to a designer/manufacturer an unforeseen or unanticipated occurrence which could cause failures, delays, or additional cost. Only those unexpected problems that may occur due to the nature of aerospace experiment environmental and operational requirements are included.

Characterising weak layers that accommodate submarine landslides on the Northwest African continental slope

NASA Astrophysics Data System (ADS)

Urlaub, M.; Krastel, S.; Geersen, J.; Schwenk, T.

2017-12-01

Numerous studies invoke weak layers to explain the occurrence of large submarine landslides (>100 km³), in particular those on very gentle slopes (<3°). Failure conditions are thought to be met only within this layer, which is embedded between stable sediments. Although key to understanding failure mechanisms, little is known about the nature and composition of such weak layers, mainly because they are (1) often destroyed with the landslide and (2) difficult to reach with ship-based gravity and piston coring. The Northwest African continental slope hosts numerous large submarine landslides that are translational, such that failure takes place along bedding-parallel surfaces at different stratigraphic depths. This suggests that failure occurs along weak layers, which are deposited repeatedly over time. Using high resolution seismic reflection data we trace several failure surfaces of the Cap Blanc Slide complex offshore Northwest Africa to ODP-Site 658. Core-seismic integration shows that the failure surfaces coincide with diatom oozes that are topped by clay. Along Northwest Africa diatom-rich sediments are typically deposited at the end of glacial periods. In the seismic data these oozes show up as distinct high amplitude reflectors due to their characteristic low densities. Similar high-amplitude reflectors embedded into low-reflective seismic units are commonly observed in shallow sediments (<100 m below seafloor) along the entire Northwest African continental slope. The failure surfaces of at least three large landslides coincide with such reflectors. As the most recent Pleistocene glacial periods likely influenced sediment deposition along the entire Northwest African margin in a similar manner we hypothesize that diatom oozes play a critical role for the generation of submarine landslides off Northwest Africa as well as globally within subtropical regions. An initiative to drill the Northwest African continental slope with IODP is ongoing, within which this hypothesis shall be tested.

A multi-sensor approach to landslide monitoring of rainfall-induced failures in Scotland.

NASA Astrophysics Data System (ADS)

Gilles, Charlie; Hoey, Trevor; Williams, Richard

2017-04-01

Landslides are of significant interest in upland areas of the United Kingdom due to their: complex mechanics, potential to channelize into hazardous debris flows and their costly potential impacts on infrastructure. The British Geological Survey National Landslide Database contains an average of 367 landslides per year (from 1970). Slope failures in the UK are typically triggered by extended periods of intense rainfall, and can occur at any time of year. In any given rainfall event that triggers landslides, most potentially vulnerable slopes remain stable. Accurate warning systems would be facilitated by identifying landslide precursors prior to failure events. This project tests whether such precursors can be identified in the valley of Glen Ogle, Scotland (87 km north-west of Edinburgh), where in summer 2004 two debris flows blocked the main road (A85), trapping fifty-seven people. Two adjacent sites have been selected on a west facing slope in Glen Ogle, one of which (the control) has been stable since at least 2004 and the other failed in 2004 and remains unstable. Understanding the immediate causes and antecedent conditions responsible for landslides requires a multi-scale approach. This project uses multiple sensors to assess failure mechanisms of landslides in Glen Ogle: (1) 3-monthly, high (1.8 arcsec) resolution terrestrial laser scanning of topography to detect changes and identify patterns of movement prior to major failure, using the Riegl VZ-1000 (NERC Geophysical Equipment Fund); (2) rainfall and soil moisture data to monitor pore pressure of landslide failure prior to and after hydrologically triggered events; (3) monitoring ground motion using grain-scale sensors which are becoming lower cost, more efficient in terms of power, and can be wirelessly networked these will be used to detect small scale movement of the landslide. Comparative data from the control and test sites will be presented, from which patterns of surface deformation between failure events will be derived.

Identification of priorities for medication safety in neonatal intensive care.

PubMed

Kunac, Desireé L; Reith, David M

2005-01-01

Although neonates are reported to be at greater risk of medication error than infants and older children, little is known about the causes and characteristics of error in this patient group. Failure mode and effects analysis (FMEA) is a technique used in industry to evaluate system safety and identify potential hazards in advance. The aim of this study was to identify and prioritize potential failures in the neonatal intensive care unit (NICU) medication use process through application of FMEA. Using the FMEA framework and a systems-based approach, an eight-member multidisciplinary panel worked as a team to create a flow diagram of the neonatal unit medication use process. Then by brainstorming, the panel identified all potential failures, their causes and their effects at each step in the process. Each panel member independently rated failures based on occurrence, severity and likelihood of detection to allow calculation of a risk priority score (RPS). The panel identified 72 failures, with 193 associated causes and effects. Vulnerabilities were found to be distributed across the entire process, but multiple failures and associated causes were possible when prescribing the medication and when preparing the drug for administration. The top ranking issue was a perceived lack of awareness of medication safety issues (RPS score 273), due to a lack of medication safety training. The next highest ranking issues were found to occur at the administration stage. Common potential failures related to errors in the dose, timing of administration, infusion pump settings and route of administration. Perceived causes were multiple, but were largely associated with unsafe systems for medication preparation and storage in the unit, variable staff skill level and lack of computerised technology. Interventions to decrease medication-related adverse events in the NICU should aim to increase staff awareness of medication safety issues and focus on medication administration processes.

Three dimensional contact/impact methodology

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

Kulak, R.F.

1987-01-01

The simulation of three-dimensional interface mechanics between reactor components and structures during static contact or dynamic impact is necessary to realistically evaluate their structural integrity to off-normal loads. In our studies of postulated core energy release events, we have found that significant structure-structure interactions occur in some reactor vessel head closure designs and that fluid-structure interactions occur within the reactor vessel. Other examples in which three-dimensional interface mechanics play an important role are: (1) impact response of shipping casks containing spent fuel, (2) whipping pipe impact on reinforced concrete panels or pipe-to-pipe impact after a pipe break, (3) aircraft crashmore » on secondary containment structures, (4) missiles generated by turbine failures or tornados, and (5) drops of heavy components due to lifting accidents. The above is a partial list of reactor safety problems that require adequate treatment of interface mechanics and are discussed in this paper.« less

Retrieval Failure Contributes to Gist-Based False Recognition

PubMed Central

Guerin, Scott A.; Robbins, Clifford A.; Gilmore, Adrian W.; Schacter, Daniel L.

2011-01-01

People often falsely recognize items that are similar to previously encountered items. This robust memory error is referred to as gist-based false recognition. A widely held view is that this error occurs because the details fade rapidly from our memory. Contrary to this view, an initial experiment revealed that, following the same encoding conditions that produce high rates of gist-based false recognition, participants overwhelmingly chose the correct target rather than its related foil when given the option to do so. A second experiment showed that this result is due to increased access to stored details provided by reinstatement of the originally encoded photograph, rather than to increased attention to the details. Collectively, these results suggest that details needed for accurate recognition are, to a large extent, still stored in memory and that a critical factor determining whether false recognition will occur is whether these details can be accessed during retrieval. PMID:22125357

Measurement of the residual stress in hot rolled strip using strain gauge method

NASA Astrophysics Data System (ADS)

Kumar, Lokendra; Majumdar, Shrabani; Sahu, Raj Kumar

2017-07-01

Measurement of the surface residual stress in a flat hot rolled steel strip using strain gauge method is considered in this paper. Residual stresses arise in the flat strips when the shear cut and laser cut is applied. Bending, twisting, central buckled and edge waviness is the common defects occur during the cutting and uncoiling process. These defects arise due to the non-uniform elastic-plastic deformation, phase transformation occurring during cooling and coiling-uncoiling process. The residual stress analysis is very important because with early detection it is possible to prevent an object from failure. The goal of this paper is to measure the surface residual stress in flat hot rolled strip using strain gauge method. The residual stress was measured in the head and tail end of hot rolled strip considering as a critical part of the strip.

Molasses as an external carbon source for anaerobic treatment of sulphite evaporator condensate.

PubMed

Silva, Flávio; Nadais, Helena; Prates, António; Arroja, Luís; Capela, Isabel

2009-03-01

Failures in stability and COD removal performance often occurred in full-scale anaerobic reactors treating the evaporator condensate from a sulphite pulp mill due to substrate inhibition and occasional contaminations with red liquor (wood cooking liquor). With this work, the beneficial effect provided by the continuous addition of an external carbon source (sugarcane molasses) on the overall performance and stability of the biological process was evaluated. With a moderate addition of molasses the inhibition was mitigated which led to an increase of the COD removal rate from 52% to 77% and a methane production increase from 460 to 1650mld(-1) at an organic loading rate of 2.61g CODl(-1)d(-1). A similar conclusion can be drawn for the case when contamination with red liquor occurs. These results suggest that sugarcane molasses addition may be regarded as a low-cost operational strategy for the anaerobic treatment of sulphite evaporator condensate.

Debonding characteristics of adhesively bonded woven Kevlar composites

NASA Technical Reports Server (NTRS)

Mall, S.; Johnson, W. S.

1988-01-01

The fatigue damage mechanism of an adhesively bonded joint between fabric reinforced composite adherends was investigated with cracked-lap-shear specimens. Two bonded systems were studied: fabric Kevlar 49/5208 epoxy adherends bonded together with either EC 3445 or FM-300 adhesive. For each bonded system, two specimen geometries were tested. In all specimens tested, fatigue damage occurred in the form of cyclic debonding; however, the woven Kevlar specimens gave significantly slower debond growth rates and higher fracture toughness than previously found in the nonwoven adherend specimens. The surfaces for the woven adherends were not smooth; rather, they had regular crests (high spots) and troughs (low spots) due to the weave pattern. Radiographs of the specimens and examination of their failure surfaces revealed that fiber bridging occurred between the crests of the two adherends in the debonded region. The observed improvements in debond growth resistance and static fracture toughness are attributed to this bridging.

Work-related fatalities among youth ages 11-17 in North Carolina, 1990-2008.

PubMed

Rauscher, Kimberly J; Runyan, Carol W; Radisch, Deborah

2011-02-01

Local and national surveillance systems are in place that identify occupational deaths. However, due to certain restrictions, they are limited in their ability to accurately count these deaths among adolescent workers. In this population-based study, we relied on primary data from the North Carolina medical examiner system to identify and describe all work-related fatalities among North Carolina youth under age 18 between 1990 and 2008. We identified 31 work-related deaths among youth ages 11-17. The majority occurred between 1990 and 1999. Most occurred in construction and agriculture. Vehicles and guns were responsible for the majority of deaths. Although the prevalence of adolescent work-related fatalities has seen a decline in North Carolina, the 31 deaths we detected signal a failure of the systems in place to prevent young worker fatalities. More remains to be done to protect the lives of adolescent workers. Copyright © 2010 Wiley-Liss, Inc.

Failure mechanisms of uni-ply composite plates with a circular hole under static compressive loading

NASA Technical Reports Server (NTRS)

Khamseh, A. R.; Waas, A. M.

1992-01-01

The objective of the study was to identify and study the failure mechanisms associated with compressive-loaded uniply graphite/epoxy square plates with a central circular hole. It is found that the type of compressive failure depends on the hole size. For large holes with the diameter/width ratio exceeding 0.062, fiber buckling/kinking initiated at the hole is found to be the dominant failure mechanism. In plates with smaller hole sizes, failure initiates away from the hole edge or complete global failure occurs. Critical buckle wavelengths at failure are presented as a function of the normalized hole diameter.

Low-Stress Upper Plate Near Subduction Zones and Implications for Temporal Changes in Loading Forces

NASA Astrophysics Data System (ADS)

Wang, K.; Hu, Y.; Yoshida, K.

2016-12-01

Subduction megathrusts are weak, often with effective friction coefficients as low as 0.03. Consequently, differential stress (S1 - S3) in the nearby upper plate is low. Compression due to plate coupling and tension due to gravity are in a subtle balance that can be tipped by small perturbations. For example, the 2011 M=9 Tohoku-oki earthquake, which has a rupture-zone-average stress drop of only a few MPa, switched offshore margin-normal stress from compression to tension and affected seismicity pattern and stress directions of various parts of the land area. The low differential stress is also reflected in spatial variations of stresses, such as with changes in topography. In the Andes, crustal earthquake focal mechanisms change from thrust-faulting in low-elevation areas to normal-faulting in high-elevation areas. Given the lack of evidence for a pervasively weak crust, the low differential stress may indicate that in general the crust near subduction zones is not critically stressed. If so, crustal earthquakes do not represent pervasive failure but only local failure due to stress, material, and fluid pressure heterogeneity. If distributed permanent deformation that creates topography is not the norm, it either happens in brief episodes or took place in the past. The outer wedge may enter a compressively or extensionally critical state due to coseismic strengthening or weakening, respectively, of the shallow megathrust in largest interplate earthquakes. Temporal changes in loading forces must occur also at much larger temporal and spatial scales in response to changes in the nature of the subducting plate and other tectonic conditions. We propose that submarine wedges and high topography in the upper plate attain their geometry in geologically brief episodes of high differential stress. They normally stay in a low-stress stable state, but their geometry often reflects high-stress episodes of critical states in the past. In other words, rocks have a sustained memory for the most traumatic moments. Except for the weaker outer wedge, the upper plate does not switch from one critical state to another in megathrust earthquake cycles, such as from compressional failure to gravitational collapse.

Clinical features and predictors of outcome in acute hepatitis A and hepatitis E virus hepatitis on cirrhosis.

PubMed

Radha Krishna, Yellapu; Saraswat, Vivek Anand; Das, Khaunish; Himanshu, Goel; Yachha, Surender Kumar; Aggarwal, Rakesh; Choudhuri, Gour

2009-03-01

Acute hepatitis A and E are recognized triggers of hepatic decompensation in patients with cirrhosis, particularly from the Indian subcontinent. However, the resulting acute-on-chronic liver failure (ACLF) has not been well characterized and no large studies are available. Our study aimed to evaluate the clinical profile and predictors of 3-month mortality in patients with this distinctive form of liver failure. ACLF was diagnosed in patients with acute hepatitis A or E [abrupt rise in serum bilirubin and/or alanine aminotransferase with positive immunoglobulin M anti-hepatitis A virus (HAV)/anti-hepatitis E virus (HEV)] presenting with clinical evidence of liver failure (significant ascites and/or hepatic encephalopathy) and clinical, biochemical, endoscopic (oesophageal varices at least grade II in size), ultrasonographical (presence of nodular irregular liver with porto-systemic collaterals) or histological evidence of cirrhosis. Clinical and laboratory profile were evaluated, predictors of 3-month mortality were determined using univariate and multivariate logistic regression and a prognostic model was constructed. Receiver-operating curves were plotted to measure performance of the present prognostic model, model for end-stage liver disease (MELD) score and Child-Turcotte-Pugh (CTP) score. ACLF occurred in 121 (3.75%) of 3220 patients (mean age 36.3+/-18.0 years; M:F 85:36) with liver cirrhosis admitted from January 2000 to June 2006. It was due to HEV in 80 (61.1%), HAV in 33 (27.2%) and both in 8 (6.1%). The underlying liver cirrhosis was due to HBV (37), alcohol (17), Wilson's disease (8), HCV (5), autoimmune (6), Budd-Chiari syndrome (2), haemochromatosis (2) and was cryptogenic in the rest (42). Common presentations were jaundice (100%), ascites (78%) and hepatic encephalopathy (55%). Mean (SD) CTP score was 11.4+/-1.6 and mean MELD score was 28.6+/-9.06. Three-month mortality was 54 (44.6%). Complications seen were sepsis in 42 (31.8%), renal failure in 45 (34%), spontaneous bacterial peritonitis in 27 (20.5%), UGI bleeding in 15(11%) and hyponatraemia in 50 (41.3%). On univariate analysis, ascites, hepatic encephalopathy, renal failure, GI bleeding, total bilirubin, hyponatraemia and coagulopathy were significant predictors of mortality. Multivariate analysis revealed grades 3 and 4 HE [odds ratio (OR 32.1)], hyponatraemia (OR 9.2) and renal failure (OR 16.8) as significant predictors of 3-month mortality and a prognostic model using these predictors was constructed. Areas under the curve for the present predicted prognostic model, MELD, and CTP were 0.952, 0.941 and 0.636 respectively. ACLF due to hepatitis A or E super infection results in significant short-term mortality. The predictors of ominous outcome include grades 3 and 4 encephalopathy, hyponatraemia and renal failure. Present prognostic model and MELD scoring system were better predictors of 3-month outcome than CTP score in these patients. Early recognition of those with dismal prognosis may permit timely use of liver replacement/supportive therapies.

Geological hazards associated with intense rain and flooding in Natal

NASA Astrophysics Data System (ADS)

Thomas, M. A.; van Schalkwyk, A.

1993-02-01

The combination of rugged topography and climate predisposes the province of Natal to severe floods. Information available since 1856 shows that bridge and slope failures have been recorded in twenty out of twenty-five flood episodes. Bridge failures are caused mostly by geological factors. The mechanism of failure can be classified broadly into foundation failures and changes of river course. Scour and debris build-up have led to failures of foundations located in rock and alluvial sediments. In preparing and replacing bridges the aims have been to increase the area of waterway, increase foundation depths to reach more competent strata and lay protection along banks and abutments to counteract scour. Historically, slope failures have not been well documented but following the 1987/88 storms 223 slope failures were recorded. The classification of the failures allowed the mechanisms of failure to be ascertained, and general design considerations to be reviewed. In areas adjacent to the Drakensberg Mountains slope failures are part of a natural erosion cycle which may be accelerated in periods of heavy rain. Throughout Natal, hummocky ground adjacent to dolerite intrusions reveals the on-going history of failure caused by water ingress and the generation of high pore water pressures on the slip planes. Classic flows occurred throughout the Greater Durban area where residual sandy soils of the Natal Group sandstone became supersaturated. Slumping was common on steep terrain underlain by granite-gneiss in the Kwa-Zulu area. Shales of the Pietermaritzburg Formation are notoriously unstable, yet few failures occurred during the summer storms of 1987/88. Inadequate drainage was responsible for many failures, this was particularly so along the railways.

[Renal failure in patients with liver transplant: incidence and predisposing factors].

PubMed

Gerona, S; Laudano, O; Macías, S; San Román, E; Galdame, O; Torres, O; Sorkin, E; Ciardullo, M; de Santibañes, E; Mastai, R

1997-01-01

Renal failure is a common finding in patients undergoing orthotopic liver transplantation. The aim of the present study was to evaluate the incidence, prognostic value of pre, intra and postoperative factors and severity of renal dysfunction in patients who undergo liver transplantation. Therefore, the records of 38 consecutive adult patients were reviewed. Renal failure was defined arbitrarily as an increase in creatinine (> 1.5 mg/dl) and/or blood urea (> 80 mg/dl). Three patients were excluded of the final analysis (1 acute liver failure and 2 with a survival lower than 72 hs.) Twenty one of the 35 patients has renal failure after orthotopic liver transplantation. Six of these episodes developed early, having occurred within the first 6 days. Late renal impairment occurred in 15 patients within the hospitalization (40 +/- 10 days) (Mean +/- SD). In he overall series, liver function, evaluated by Child-Pugh classification, a higher blood-related requirements and cyclosporine levels were observed more in those who experienced renal failure than those who did not (p < 0.05). Early renal failure was related with preoperative (liver function) and intraoperative (blood requirements) factors and several causes (nephrotoxic drugs and graft failure) other than cyclosporine were present in patients who developed late renal impairment. No mortality. No mortality was associated with renal failure. We conclude that renal failure a) is a common finding after liver transplantation, b) the pathogenesis of this complication is multifactorial and, c) in not related with a poor outcome.

Premonitory slip and tidal triggering of earthquakes

USGS Publications Warehouse

Lockner, D.A.; Beeler, N.M.

1999-01-01

We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10-4 and 10-6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sources. The period of the modulating signal ranged from 10 to 10,000 s. For each combination of amplitude and period of the modulating signal, multiple stick-slip events were recorded to determine the degree of correlation between the timing of simulated earthquakes and the imposed periodic loading function. Over the range of parameters studied, the degree of correlation of earthquakes was most sensitive to the amplitude of the periodic loading, with weaker dependence on the period of oscillations and the average loading rate. Accelerating premonitory slip was observed in these experiments and is a controlling factor in determining the conditions under which correlated events occur. In fact, some form of delayed failure is necessary to produce the observed correlations between simulated earthquake timing and characteristics of the periodic loading function. The transition from strongly correlated to weakly correlated model earthquake populations occurred when the amplitude of the periodic loading was approximately 0.05 to 0.1 MPa shear stress (0.03 to 0.06 MPa Coulomb failure function). Lower-amplitude oscillations produced progressively lower correlation levels. Correlations between static stress increases and earthquake aftershocks are found to degrade at similar stress levels. Typical stress variations due to Earth tides are only 0.001 to 0.004 MPa, so that the lack of correlation between Earth tides and earthquakes is also consistent with our findings. A simple extrapolation of our results suggests that approximately 1% of midcrustal earthquakes should be correlated with Earth tides. Triggered seismicity has been reported resulting from the passage of surface waves excited by the Landers earthquake. These transient waves had measured amplitudes in excess of 0.1 MPa at frequencies of 0.05 to 0.2 Hz in regions of notable seismicity increase. Similar stress oscillations in our laboratory experiments produced strongly correlated stick-slip events. We suggest that seemingly inconsistent natural observations of triggered seismicity and absence of tidal triggering indicate that failure is amplitude and frequency dependent. This is the expected result if, as in our laboratory experiments, the rheology of the Earth's crust permits delayed failure.

Design Against Propagating Shear Failure in Pipelines

NASA Astrophysics Data System (ADS)

Leis, B. N.; Gray, J. Malcolm

Propagating shear failure can occur in gas and certain hazardous liquid transmission pipelines, potentially leading to a large long-burning fire and/or widespread pollution, depending on the transported product. Such consequences require that the design of the pipeline and specification of the steel effectively preclude the chance of propagating shear failure. Because the phenomenology of such failures is complex, design against such occurrences historically has relied on full-scale demonstration experiments coupled with empirically calibrated analytical models. However, as economic drivers have pushed toward larger diameter higher pressure pipelines made of tough higher-strength grades, the design basis to ensure arrest has been severely compromised. Accordingly, for applications where the design basis becomes less certain, as has occurred increasing as steel grade and toughness has increased, it has become necessary to place greater reliance on the use and role of full-scale testing.

An improved ant colony optimization algorithm with fault tolerance for job scheduling in grid computing systems

PubMed Central

Idris, Hajara; Junaidu, Sahalu B.; Adewumi, Aderemi O.

2017-01-01

The Grid scheduler, schedules user jobs on the best available resource in terms of resource characteristics by optimizing job execution time. Resource failure in Grid is no longer an exception but a regular occurring event as resources are increasingly being used by the scientific community to solve computationally intensive problems which typically run for days or even months. It is therefore absolutely essential that these long-running applications are able to tolerate failures and avoid re-computations from scratch after resource failure has occurred, to satisfy the user’s Quality of Service (QoS) requirement. Job Scheduling with Fault Tolerance in Grid Computing using Ant Colony Optimization is proposed to ensure that jobs are executed successfully even when resource failure has occurred. The technique employed in this paper, is the use of resource failure rate, as well as checkpoint-based roll back recovery strategy. Check-pointing aims at reducing the amount of work that is lost upon failure of the system by immediately saving the state of the system. A comparison of the proposed approach with an existing Ant Colony Optimization (ACO) algorithm is discussed. The experimental results of the implemented Fault Tolerance scheduling algorithm show that there is an improvement in the user’s QoS requirement over the existing ACO algorithm, which has no fault tolerance integrated in it. The performance evaluation of the two algorithms was measured in terms of the three main scheduling performance metrics: makespan, throughput and average turnaround time. PMID:28545075

Investigation of a Modified 9Cr-1Mo (P91) Pipe Failure

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

Klueh, Ronald L; Shingledecker, John P

2006-04-01

A modified 9Cr-1Mo feedwater (condensate) line at an Eastman Chemical Company plant failed in January 2005. The line was in continuous service since start-up December 2001 until failure. The Plant Superintendent estimated there were three thermal cycles since start-up, although there may have been as many as 25 thermal cycles during commissioning. Normal operating temperature was 325 F (163 C) and pressure was 1762 psig. The line was steam traced with the tracing activated only when ambient outdoor temperature dropped to 40 F (5 C). A modified 9Cr-1Mo steel (P91) pipe failure in a feedwater line in a chemical plantmore » was investigated. The failure occurred in the vicinity of an elbow produced with socket welds of the pipe to the elbow. Based on metallography and hardness measurements, it was concluded that failure occurred because of an improper post-weld heat treatment of the socket weldment.« less

Compression Fracture of CFRP Laminates Containing Stress Intensifications.

PubMed

Leopold, Christian; Schütt, Martin; Liebig, Wilfried V; Philipkowski, Timo; Kürten, Jonas; Schulte, Karl; Fiedler, Bodo

2017-09-05

For brittle fracture behaviour of carbon fibre reinforced plastics (CFRP) under compression, several approaches exist, which describe different mechanisms during failure, especially at stress intensifications. The failure process is not only initiated by the buckling fibres, but a shear driven fibre compressive failure beneficiaries or initiates the formation of fibres into a kink-band. Starting from this kink-band further damage can be detected, which leads to the final failure. The subject of this work is an experimental investigation on the influence of ply thickness and stacking sequence in quasi-isotropic CFRP laminates containing stress intensifications under compression loading. Different effects that influence the compression failure and the role the stacking sequence has on damage development and the resulting compressive strength are identified and discussed. The influence of stress intensifications is investigated in detail at a hole in open hole compression (OHC) tests. A proposed interrupted test approach allows identifying the mechanisms of damage initiation and propagation from the free edge of the hole by causing a distinct damage state and examine it at a precise instant of time during fracture process. Compression after impact (CAI) tests are executed in order to compare the OHC results to a different type of stress intensifications. Unnotched compression tests are carried out for comparison as a reference. With this approach, a more detailed description of the failure mechanisms during the sudden compression failure of CFRP is achieved. By microscopic examination of single plies from various specimens, the different effects that influence the compression failure are identified. First damage of fibres occurs always in 0°-ply. Fibre shear failure leads to local microbuckling and the formation and growth of a kink-band as final failure mechanisms. The formation of a kink-band and finally steady state kinking is shifted to higher compressive strains with decreasing ply thickness. Final failure mode in laminates with stress intensification depends on ply thickness. In thick or inner plies, damage initiates as shear failure and fibre buckling into the drilled hole. The kink-band orientation angle is changing with increasing strain. In outer or thin plies shear failure of single fibres is observed as first damage and the kink-band orientation angle is constant until final failure. Decreasing ply thickness increases the unnotched compressive strength. When stress intensifications are present, the position of the 0°-layer is critical for stability under compression and is thus more important than the ply thickness. Central 0°-layers show best results for OHC and CAI strength due to higher bending stiffness and better supporting effect of the adjacent layers.

Compression Fracture of CFRP Laminates Containing Stress Intensifications

PubMed Central

Schütt, Martin; Philipkowski, Timo; Kürten, Jonas; Schulte, Karl

2017-01-01

For brittle fracture behaviour of carbon fibre reinforced plastics (CFRP) under compression, several approaches exist, which describe different mechanisms during failure, especially at stress intensifications. The failure process is not only initiated by the buckling fibres, but a shear driven fibre compressive failure beneficiaries or initiates the formation of fibres into a kink-band. Starting from this kink-band further damage can be detected, which leads to the final failure. The subject of this work is an experimental investigation on the influence of ply thickness and stacking sequence in quasi-isotropic CFRP laminates containing stress intensifications under compression loading. Different effects that influence the compression failure and the role the stacking sequence has on damage development and the resulting compressive strength are identified and discussed. The influence of stress intensifications is investigated in detail at a hole in open hole compression (OHC) tests. A proposed interrupted test approach allows identifying the mechanisms of damage initiation and propagation from the free edge of the hole by causing a distinct damage state and examine it at a precise instant of time during fracture process. Compression after impact (CAI) tests are executed in order to compare the OHC results to a different type of stress intensifications. Unnotched compression tests are carried out for comparison as a reference. With this approach, a more detailed description of the failure mechanisms during the sudden compression failure of CFRP is achieved. By microscopic examination of single plies from various specimens, the different effects that influence the compression failure are identified. First damage of fibres occurs always in 0°-ply. Fibre shear failure leads to local microbuckling and the formation and growth of a kink-band as final failure mechanisms. The formation of a kink-band and finally steady state kinking is shifted to higher compressive strains with decreasing ply thickness. Final failure mode in laminates with stress intensification depends on ply thickness. In thick or inner plies, damage initiates as shear failure and fibre buckling into the drilled hole. The kink-band orientation angle is changing with increasing strain. In outer or thin plies shear failure of single fibres is observed as first damage and the kink-band orientation angle is constant until final failure. Decreasing ply thickness increases the unnotched compressive strength. When stress intensifications are present, the position of the 0°-layer is critical for stability under compression and is thus more important than the ply thickness. Central 0°-layers show best results for OHC and CAI strength due to higher bending stiffness and better supporting effect of the adjacent layers. PMID:28872623

International Space Station (ISS) Environmental Control and Life Support (ECLS) System Overview of Events: February 2002 - 2004

NASA Technical Reports Server (NTRS)

Gentry, Gregory J.; Reysa, Richard P.; Williams, Dave E.

2004-01-01

The International Space Station continues to build up its life support equipment capability. Several ECLS equipment failures have occurred since Lab activation in February 2001. Major problems occurring between February 2001 and February 2002 were discussed in other works. Major problems occurring between February 2002 and February 2003 are discussed in this paper, as are updates from previously ongoing unresolved problems. This paper addresses failures, and root cause, with particular emphasis on likely micro-gravity causes. Impact to overall station operations and proposed and accomplished fixes will also be discussed.

A multiscale structural investigation of the annulus-endplate anchorage system and its mechanisms of failure.

PubMed

Rodrigues, Samantha A; Thambyah, Ashvin; Broom, Neil D

2015-03-01

The annulus-endplate anchorage system performs a critical role in the disc, creating a strong structural link between the compliant annulus and the rigid vertebrae. Endplate failure is thought to be associated with disc herniation, a recent study indicating that this failure mode occurs more frequently than annular rupture. The aim was to investigate the structural principles governing annulus-endplate anchorage and the basis of its strength and mechanisms of failure. Loading experiments were performed on ovine lumbar motion segments designed to induce annulus-endplate failure, followed by macro- to micro- to fibril-level structural analyses. The study was funded by a doctoral scholarship from our institution. Samples were loaded to failure in three modes: torsion using intact motion segments, in-plane tension of the anterior annulus-endplate along one of the oblique fiber angles, and axial tension of the anterior annulus-endplate. The anterior region was chosen for its ease of access. Decalcification was used to investigate the mechanical influence of the mineralized component. Structural analysis was conducted on both the intact and failed samples using differential interference contrast optical microscopy and scanning electron microscopy. Two main modes of anchorage failure were observed--failure at the tidemark or at the cement line. Samples subjected to axial tension contained more tidemark failures compared with those subjected to torsion and in-plane tension. Samples decalcified before testing frequently contained damage at the cement line, this being more extensive than in fresh samples. Analysis of the intact samples at their anchorage sites revealed that annular subbundle fibrils penetrate beyond the cement line to a limited depth and appear to merge with those in the vertebral and cartilaginous endplates. Annulus-endplate anchorage is more vulnerable to failure in axial tension compared with both torsion and in-plane tension and is probably due to acute fiber bending at the soft-hard interface of the tidemark. This finding is consistent with evidence showing that flexion, which induces a similar pattern of axial tension, increases the risk of herniation involving endplate failure. The study also highlights the important strengthening role of calcification at this junction and provides new evidence of a fibril-based form of structural integration across the cement line. Copyright © 2015 Elsevier Inc. All rights reserved.

Investigating compression failure mechanisms in composite laminates with a transparent fiberglass-epoxy birefringent materials

NASA Technical Reports Server (NTRS)

Shuart, M. J.; Williams, J. G.

1984-01-01

The response and failure of a + or - 45s class laminate was studied by transparent fiberglass epoxy composite birefringent material. The birefringency property allows the laminate stress distribution to be observed during the test and also after the test if permanent residual stresses occur. The location of initial laminate failure and of the subsequent failure propagation are observed through its transparency characteristics. Experimental results are presented.

Operational Design of Campaigns. A Hedge against Operational Failures.

DTIC Science & Technology

1990-05-07

must be accomplished to ensure 7 guccegg. When minfortunes occur, they can be traced to the inability of the military organization to: learn the lessons...of Campaigns What can be learned from the British experience in the early years of the Mesopotamia Campaign? First, it is vitally important for policy...roots in one of three organizational failurea. They are the failure to learn , the failure to anticipate and the failure to adapt." Military

Neuropathologic Studies of the Baltimore Longitudinal Study of Aging (BLSA)

PubMed Central

O’Brien, Richard J.; Resnick, Susan M.; Zonderman, Alan B.; Ferrucci, Luigi; Crain, Barbara J.; Pletnikova, Olga; Rudow, Gay; Iacono, Diego; Riudavets, Miguel A.; Driscoll, Ira; Price, Donald L.; Martin, Lee J.; Troncoso, Juan C.

2010-01-01

The Baltimore Longitudinal Study of Aging (BLSA) was established in 1958 and is one the oldest prospective studies of aging in the USA and the world. The BLSA is supported by the National Institute of Aging (NIA) and its mission is to learn what happens to people as they get old and how to sort out changes due to aging and from those due to disease or other causes. In 1986, an autopsy program combined with comprehensive neurologic and cognitive evaluations was established in collaboration with the Johns Hopkins University Alzheimer’s Disease Research Center (ADRC). Since then, 211 subjects have undergone autopsy. Here we review the key clinical neuropathological correlations from this autopsy series. The focus is on the morphological and biochemical changes that occur in normal aging, and the early neuropathological changes of neurodegenerative diseases, especially Alzheimer’s disease (AD). We highlight the combined clinical, pathologic, morphometric, and biochemical evidence of asymptomatic AD, a state characterized by normal clinical evaluations in subjects with abundant AD pathology. We conclude that in some individuals, successful cognitive aging results from compensatory mechanisms that occur at the neuronal level (i.e., neuronal hypertrophy and synaptic plasticity) whereas a failure of compensation may culminate in disease. PMID:19661626

A comparison of successful and unsuccessful attempts in maximal bench pressing.

PubMed

van den Tillaar, Roland; Ettema, Gertjan

2009-11-01

This study was designed to compare the differences in EMG and kinematics between successful and unsuccessful attempts in bench pressing at one repetition maximum (1RM) in recreational weight-trained subjects. We hypothesized that failure occurs during the sticking period (the period during which there is a temporary reduction in movement velocity). Eleven male subjects (age = 21.9 +/- 1.8 yr, mass = 80.0 +/- 11.2 kg, height = 1.79 +/- 0.08 m) with at least 1 yr of bench press training experience participated in this study. They performed attempts at 1RM and 1RM + 2.5 kg in bench press during which kinematics and muscle activity were recorded. One successful attempt and one unsuccessful attempt were used for further analysis. Both attempts showed the same sticking period, but only half of the failures occurred during that period. The main differences in the kinematics occurred during the sticking period. Muscle activity, in contrast, showed the same pattern in both attempts and only differed during the downward and the start of the upward movement of the lift. The sticking period occurs in both successful and unsuccessful attempts in maximal bench press. However, failure does not always occur during the sticking period.

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