Higher Chance Of Failure Research Articles

Stochastic bilevel interdiction for fake news control in online social networks

Social media platforms attempt to mitigate and control fake news, using interventions such as flagging posts or adjusting newsfeed algorithms, to protect vulnerable individuals. In this paper, we consider performing intervention actions on specific source nodes or user–user edges in social networks, under uncertain effectiveness of different intervention strategies. We model misinformation from malicious users to vulnerable communities using stochastic network interdiction formulations. Specifically, we minimize the expected number of reachable vulnerable users via stochastic maximum flow, and develop an alternative formulation for handling large-scale social networks based on their topological structures. We derive theoretical results for path-based networks and develop an approximate algorithm for single-edge removal on paths. We test instances of a social network with 23,505 nodes, based on the IMDb actors dataset, to demonstrate the scalability of the approach and its effectiveness. Via numerical studies, we find that characteristics of removed edges change when intervention effectiveness is stochastic. Our results suggest that intervention should target on (i) a smaller set of centrally located edges with nodes that represent communities where regulatory actions are more effective, and (ii) dispersed edges with nodes where intervention has a high chance of failure.

Investigating the effect of autograft diameter for quadriceps and patellar tendons use in anterior cruciate ligament reconstruction: a biomechanical analysis using a simulated Lachman test.

Current clinical practice suggests using patellar and quadriceps tendon autografts with a 10 mm diameter for ACL reconstruction. This can be problematic for patients with smaller body frames. Our study objective was to determine the minimum diameter required for these grafts. We hypothesize that given the strength and stiffness of these respective tissues, they can withstand a significant decrease in diameter before demonstrating mechanical strength unviable for recreating the knee's stability. We created a finite element model of the human knee with boundary conditions characteristic of the Lachman test, a passive accessory movement test of the knee performed to identify the integrity of the anterior cruciate ligament (ACL). The Mechanical properties of the model's grafts were directly obtained from cadaveric testing and the literature. Our model estimated the forces required to displace the tibia from the femur with varying graft diameters. The 7 mm diameter patellar and quadriceps tendon grafts could withstand 55-60 N of force before induced tibial displacement. However, grafts of 5.34- and 3.76-mm diameters could only withstand upwards of 47 N and 40 N, respectively. Additionally, at a graft diameter of 3.76 mm, the patellar tendon experienced 234% greater stiffness than the quadriceps tendon, with similar excesses of stiffness demonstrated for the 5.34- and 7-mm diameter grafts. The patellar tendon provided a stronger graft for knee reconstruction at all diameter sizes. Additionally, it experienced higher maximum stress, meaning it dissociates force better across the graft than the quadriceps tendon. Significantly lower amounts of force were required to displace the tibia for the patellar and quadriceps tendon grafts at 3.76- and 5.34-mm graft diameters. Based on this point, we conclude that grafts below the 7 mm diameter have a higher chance of failure regardless of graft selection.

Pre-morbid frailty is associated with poor outcome after thrombolysis in older patients with ST-elevation Myocardial Infarction

Introduction: In recent years, the association of frailty has been established with a poor outcome after percutaneous intervention following an acute cardiovascular event. However, a larger proportion of the world population is unable to access the prohibitively expensive tertiary cardiac care and receives the more readily available, affordable and acceptable thrombolytic therapy in emergency situations. The current study was designed to explore the association of pre-morbid frailty with immediate and short-term outcome of thrombolysis in older subjects presenting with ST-elevation myocardial infarction to our hospital. Methods: This was an observational prospective cohort study completed between 2015 and 2017 at a tertiary care teaching hospital in Delhi. Patients older than 60 years who presented to the hospital with ST-elevation myocardial infarction and underwent successful thrombolysis were included for the study. Complications such as bleeding, reperfusion reactions and allergic reactions were recorded whenever these were observed. In addition, complications such as re-infarction, stroke, cardiac arrest, cardiogenic shock and death were also recorded. In addition, a short-term outcome in terms of discharge, death, recovery was noted. A pre-morbid frailty score was historically computed with inputs from the patients and their primary caretakers using a deficit count approach on a pre-defined list of fifty self-reported deficits. The descriptive statistical analysis comprised of calculating means (standard deviations) and proportions (frequencies and percentages). The association of premorbid deficit score with thrombolysis success and other variables was tested by calculating mean ranks, and Mann Whitney U test was used as a statistical test of significance. Spearman correlation coefficient was used to determine the association between frailty and complications and morbidity and mortality indicators. Univariable logistic regression models were used to evaluate independent variables associated with outcome of thrombolysis to further explore the association between frailty and outcome. Independent variables found significantly associated with poor outcome were entered into a multivariable logistic regression model (forward) in addition to those considered scientifically relevant. Results: In the present study, we found a significant association between a higher pre-morbid frailty status assessed by an interview-based deficit count score and poorer outcome of thrombolysis. Every unit increment in the frailty deficit count score on a scale of 50 points increased the odds of failed thrombolysis by 1.14 times. Frailty was also associated with an increased risk of reperfusion arrhythmias and cardiac arrest following thrombolysis. Additionally, we noted that higher the deficit score, lesser the resolution of ST segment on ECG, 90 minutes following thrombolysis. Conclusions: Our study indicates that frailty determined by a premorbid count of health deficits is associated with the outcome of thrombolysis following myocardial infarction in older patients. The patients with greater count of deficits have a higher chance of failure. Our findings will help informed decision-making while managing older patients presenting with myocardial infarction and in-turn improve morbidity and mortality.

Effect of soil anisotropy and variability on the stability of undrained soil slope

Soil is a naturally heterogeneous material and can show significant spatial variation in strength and other properties. For silty and clayey soils, these variations are often more pronounced. Despite such variation, many past studies considered these soils as homogeneous and only considered a single set of soil parameters. This may lead to underestimation of the failure potential of geo-structure such as natural slopes, water retaining dams, retaining walls, etc. A finite element method considering soil variability should be an ideal tool to investigate the behaviour of these soils. This study adopted a 2D random finite element method to evaluate the effect of such variability on slope stability. The spatial variability was implemented by using the coefficient of variation (COV) and the spatial correlation length (θ) for cohesion. It was found that the soil slope with higher COV would have a higher chance of failure, whereas the soil slope with less COV might not show any failure. In addition, the soil with a higher θ, in general, show less potential of failure. In the literature, most studies considered an isotropic condition for the soil, i.e., θ in x and y directions are the same θx = θy, which is not realistic. Therefore, the soil anisotropy (i.e., θx ≠ θy) was considered carefully in this study. It was found that the probability of failure for anisotropic soil might be significantly higher than the isotropic soil.

Peters anomaly: An overview.

Peters anomaly (PA) is a rare, often bilateral, congenital corneal opacity, usually with a sporadic inheritance pattern, characterized by corneal opacities and irido-corneal or lenticular-corneal adhesions with a defect in the Descemet's membrane, occurring due to anterior segment dysgenesis during fetal development. Due to other ocular and systemic comorbidities, a team comprising pediatric cornea, glaucoma, and strabismus specialists in addition to a pediatrician and geneticist is necessary for the appropriate management of these children. Since the outcome of pediatric penetrating keratoplasty is variable and has a higher chance of failure when accompanied by additional procedures, such as lensectomy and vitrectomy, minimally invasive alternatives are increasingly being offered to these patients. Of note is the recently reported novel procedure: selective endothelialectomy for PA, which avoids the need for a corneal transplant and results in gradual clearing of the corneal opacity over time. In this overview, we aimed to describe the etiology, classification, pathophysiology, histopathology, clinical features, and management of PA.

Evaluation of Slope Stability at Interface using Thin Soil Material Model in Finite Element Software

Cases of landslides on clay shale slopes have been an intriguing study in Indonesia. Most of the slopes failed due to the weathering of the clay shale rock. As studies focused on the properties of clay shale, several FEM analyses indicated a unique translational type of failure between the interface of clay shale and its overburden. However, the modeling of the interface in a case study was still limited. This study aims to evaluate a landslide using a thin-soil interface model using FEM software. The model used two conditions, extreme groundwater level conditions. There were several iterations of the shear strength parameters of the interface layer conducted. Results indicated that the thin-soil interface could portray the interface condition at the landslide. Compared to laboratory interface results, the interface would fail at a high degree of saturation due to water infiltration at the surface. Also, granular overburden with high permeability had a higher chance of failure than cohesive overburden. From the results, this study opened the path to incorporating the interface layer in clay shale slope analysis. However, further studies are needed using the thin-soil interface model in other clay shale landslide cases to synthesize its repeatability.

Root canal filling materials for endodontic treatment of necrotic primary teeth: a network meta-analysis.

To investigate the effect of different root canal filling materials on the change of failure of the endodontic treatment of necrotic primary teeth. A literature search was carried out in PubMed/MEDLINE, CENTRAL, Scopus databases, and grey literature up to July 2022 selecting randomised clinical trials related to research question. Two reviewers independently selected the studies, extracted the data, and assessed the bias risk. Root canal filling materials were grouped according to the main component [iodoform (IOD), calcium hydroxide (CAOH), zinc oxide (ZO) or mix (IOD plus CAOH plus ZO) pastes]. Pairwise and network meta-analyses using the mixed treatment comparisons method were performed to compare the number of events (failure) among treatments. Odds ratio and 95% confidence intervals (CI) for calculated. Post-probabilities among treatments were also calculated and interpreted. From 1186 potentially relevant studies, 17 were selected for full-text analysis, and 7 were included in the meta-analysis, totalizing 263 teeth. In the direct evidence, ZO pastes resulted in a higher chance of failure than IOD pastes (OR 7.07 95% CI 1.02, 62.59). In the indirect evidence, there was no difference between the materials. The IOD pastes presented a high probability (81%) of being the treatment associated to lowest number of failures among all treatments. The CAOH pastes presented the highest probability of being the worst option. Studies showed high bias risk. There is currently no scientific evidence of the superiority of any one root canal filling material for endodontic treatment of necrotic primary teeth.

Crashworthiness study of UCAV’s main landing gear using explicit dynamics

In the aircraft industry, the ultimate goal in any component’s design is to minimize its weight, maximize its durability, and increasing its life while keeping its overall life cycle costs low. As technology is progressing, UCAVs are gaining more and more prominence as jet powered UCAVs are already taking to skies presenting a myriad of challenges. This is especially true in the case of Landing gears as greater crashworthiness is required in high-speed high payload UCAVs. As jet powered UCAVs have a higher touchdown velocity and thus a higher chance of failure. In this research, a category of unmanned combat aerial vehicles was picked. In that category, a number of reference unmanned combat aerial vehicles were selected to extract the required parameters and dimensions of their main landing gears from literature review and analysis. The main landing gear was then modeled in CAD. Simultaneously loading conditions were defined and loads were determined. The equivalent von mises and maximum principal stresses were obtained from finite element analysis for multiple materials using the finite element package ANSYS. These results were then in turn used to calculate the factor of safety. Furthermore, an impact analysis was carried out in this crashworthiness study using Explicit Dynamics in LS DYNA for the same material. The stress formulations and deformations in impact were highly non-linear and more realistic and accurate than in static structural. The results were then validated.

Active learning with generalized sliced inverse regression for high-dimensional reliability analysis

It is computationally expensive to predict reliability using physical models at the design stage if many random input variables exist. This work introduces a dimension reduction technique based on generalized sliced inverse regression (GSIR) to mitigate the curse of dimensionality. The proposed high dimensional reliability method enables active learning to integrate GSIR, Gaussian Process (GP) modeling, and Importance Sampling (IS), resulting in an accurate reliability prediction at a reduced computational cost. The new method consists of three core steps, 1) identification of the importance sampling region, 2) dimension reduction by GSIR to produce a sufficient predictor, and 3) construction of a GP model for the true response with respect to the sufficient predictor in the reduced-dimension space. High accuracy and efficiency are achieved with active learning that is iteratively executed with the above three steps by adding new training points one by one in the region with a high chance of failure.

A Scoring Model to Evaluate Offshore Oil Projects

Offshore oil projects are defined as mega projects that are associated with larger project size, higher complexities with inherent risks, and higher chances of failure in the investment and decision-making processes. These characteristics require significant assessment and acquisition methods in order to reduce failure. Financial analysis is the most widely used method to evaluate offshore oil projects; however, there are several other internal and external factors that affect the overall success of offshore oil projects. A comprehensive approach and advanced tools are required to evaluate factors that can have a significant impact before any investment decisions are made. This paper evaluates the important factors that influence offshore oil project investment decisions as well as score their weight of impact using a multi criteria decision model. A comprehensive literature review was conducted to recognize the complexities of these factors. Four perspectives were identified in order to assess the attributes that are necessary for successful offshore projects. These perspectives are economical, technical, political and environmental and safety. A hierarchical decision model (HDM), along with desirability curves, was implemented to evaluate offshore oil projects in order to improve investment decisions and reduce failure.

Intergranular corrosion at a modified surface layer in a supermartensitic stainless steel for chemical injection mandrel

Supermartensitic stainless steels (SMSSs) are commonly employed as pipes and mandrels in off-shore oil and gas production. These materials are known to exhibit higher corrosion resistance than conventional martensitic stainless steels and also present a lower installation cost than duplex/superduplex steels and Ni alloys. After the occurrence of a certain number of failures of mandrels, manufacturers purchased samples of pipes and forged fittings in order to promote several stress corrosion tests. In this work, the specimens obtained from a grade UNS S41426 pipe steel failed at the four point test under milder conditions than the limit of NACE 0175/ISO 15156 standard. The metallurgical analysis revealed that the pipe purchased by a specific producer has been carburized at high temperature, probably as an attempt to improve superficial hardness and wear resistance. However, it resulted in an inadequate microstructure with sensitized austenitic grains, without significant increase of superficial hardness. Consequently, the material suffered severe corrosion attack during the four point tests, indicating high chances of failure at service conditions.

Design Failure Mode and Effect Analysis – Case Study

Design-Failure mode and effect analysis (D-FMEA) is very important tool used in industries to detect failure during design stage. D-FMEA is a technique to find out causes of failure and their effects on the performance of a system(parts) during design phase. In this paper, the D-FMEA of critical components of designed automatic tilting mechanism trolley is carried out. The critical components of automatic tilting mechanism trolley are identified and analyzed by the D-FMEA tool. This paper provides risk priority number of components of trolley. The component with higher risk priority number has higher chances of failure. The risk priority number of critical components is reduced by incorporating corrective actions. This paper provides probable causes of failure, effects of failure and corrective actions to be undertaken during design phase of Automatic tilting mechanism trolley. The D-FMEA tools helps in reducing accidents.

Microbiological Characterization and Antibiotic Susceptibility Pattern of Haemophilus Influenzae Isolates from a Tertiary Care Centre in South India

Haemophilus are fastidious Gram negative bacilli, which require factor X (hemin), factor V (NAD), or both for their growth. Haemophilus influenzae is the type species, and is considered to be the most pathogenic. They are associated with many invasive infections including meningitis, epiglottitis, pneumonia, and otitis media. Serotype b is most commonly associated with infections. Haemophilus species isolated from patients in a tertiary care centre in South India were studied. Identification, serotyping and biotyping were done and antibiotic susceptibility test was performed. The incidence of H. influenzae infections in our study was 65.3 cases/100,000 persons. Serotype b was the most common (66.67%), followed by non typeable H.influenzae (NTHi) (25%). Most isolates from adults were type b, while all isolates from pediatric population were non typeable. The most common biotype was type II, followed by type I and type III. Three of 24 isolates were β lactamase producers (12.5%). One isolate was β lactamase negative Ampicillin resistant (BLNAR). Resistance to ampicillin was 16.67%. Resistance to cephalosporins and fluoroquinolones was low (4-10%). Co-trimoxazole resistance was found to be very high (75%). All isolates were susceptible to azithromycin, tetracycline, chloramphenicol and meropenem. No isolates of H.influenzae type b were obtained from the paediatric population which may be due to the introduction of Hib vaccine. The increase in resistance to commonly used antibiotics is worrisome, especially penicillins and co-trimoxazole. Use of co-trimoxazole in empirical therapy of upper and lower respiratory tract infections has a high chance of failure in the current scenario.

Exchange Nailing for Aseptic Nonunion of the Femoral Shaft after Intramedullary Nailing

Purpose Although exchange nailing is a standard method of treating femoral shaft nonunion, various rates of healing, ranging from 72% to 100%, have been reported. The purpose of this study was to evaluate the efficacy of exchange nailing in femoral shaft nonunion. Methods We retrospectively reviewed 30 cases of aseptic femoral shaft nonunion after intramedullary nailing. The mean postsurgical period of nonunion was 66.8 weeks. A nail at least 2 mm larger in diameter was selected to replace the previous nail after reaming. Distal fixation was performed using at least two interlocking screws. The success of the procedure was determined by the finding of union on simple radiographs. Possible reasons for failure were analyzed, including the location of nonunion, the type of nonunion, and the number of screws used for distal fixation. Results Of the 30 cases, 27 achieved primary healing with the technique of exchange nailing. The average time to achieve union was 23.1 weeks (range, 13.7–36.9 weeks). The three failures involved nonunion at the isthmic level (three of 15 cases), not at the infraisthmic level (zero of 15 cases). Of eight cases of oligotrophic nonunion, two (25%) failed to heal, and of 22 cases of hypertrophic nonunion, one (4.5%) failed to heal. Of 11 cases involving two screws at the distal fixation, two (18.2%) failed to heal, and of 19 cases involving three or more screws, one (5.3%) failed to heal. None of these findings was statistically significant. Conclusions Exchange nailing may enable successful healing in cases of aseptic nonunion of the femoral shaft. Although nonunion at the isthmic level, oligotrophic nonunion, and weaker distal fixation seemed to be associated with a higher chance of failure, further study is needed to confirm those findings. Keywords: Femoral shaft nonunion; Exchange nailing; Risk factors; Distal interlocking

Reconstruction Using Free Flaps for Diabetic Heel Defects: Outcomes and Risk Factor Analysis.

Overall success rate after diabetic foot reconstruction using free flap has been acceptable, but certain parts of the foot like the heel remains more challenging. This retrospective study reviewed 37 patients reconstructed with free flaps for diabetic foot ulcer on the heel region from 2008 to 2017. Flap outcome in addition to various risk factors were analyzed; arterial status on heel, the American Society of Anesthesiologists (ASA) physical status, smoking, hypertension, hypercholesterolemia, chronic renal failure patient, hemoglobin A1c level, C-reactive protein, and osteomyelitis. Overall flap survival was 73% and resulted in limb salvage and functional ambulation. Total flap loss was 27% and the majority ended up with high-level amputation. Among the risk factors evaluated, the arterial status of the heel and ASA status significantly increased the odds for failure. When both arterial branches to the heel were impaired, the odds of failure were 80 times higher to fail (p< 0.05). The vascularity of the surrounding tissue of the defect plays a critical role in overall success of diabetic heel reconstruction. Aggressive debridement using the angiosome concept is necessary to assure surrounding tissue has a good circulation. Despite the high chance of failure, success will lead to limb salvage and to reasonable functional ambulation whereas failure to salvage the heel will lead to higher level amputation. This warrants microsurgeons to make an effort to perform reconstruction to the heel defect after obtaining maximal vascularity after angioplasty.

Surveillance of infection in fractures of extremities treated with internal fixation

Infection is a major problem in orthopaedics quite often leading to implant failure. The aim of the study is to determine the outcome of infection after internal fixation of fractures and the risk for non-union in infected fractures. We evaluated 34 patients with 34 fractures that were infected after internal fixation to be followed up in this study from August 2017 to December 2018. At final follow up the surveillance showed satisfactory results in 31 (91.2%) cases and the rest 03 (8.8%) had an unfavourable outcome in terms of Non Union and persistent infection. Of the 34 patients enrolled in the study, 22 had sound bony union at the time of presentation. Of the 12 fractures which had not progressed to union, 9 eventually united. Only 3 patients showed no clinical or radiological signs of union at the end of the study. Of the 3 patients who did not achieve union by the end of the study only 1 continued to be infected. Infection persisted in 2 patients in spite of achieving good union. Statistical analysis showed association of the surgery-infection interval and the type of microorganism identified. Late infections had a higher chance of failure in culture. Infection when intervened and adequately treated does not quite appear to interfere with the process of union.

The Use of Metal Sublaminar Wires in Modern Growth-Guidance Scoliosis Surgery: A Report of 4 Cases and Literature Review

To avoid early fusion and allow residual growth of the spine in early onset scoliosis (EOS) treatment, growth-guided scoliosis surgery can be performed. Four patients with EOS are presented in which a growth-guidance instrumentation is used with sliding titanium (Ti) sublaminar cables. Residual growth of the spine can be preserved using metal sublaminar wiring; however, several drawbacks of this technique and type of material are illustrated. Four patients with progressive neuromuscular scoliosis were treated with a posterior stabilization. A fusionless growth-guidance instrumentation was used consisting of a combination of lumbar pedicle screws and sliding Ti sublaminar cables along cobalt chrome rods. In 2 cases, the described growth-guidance technique provided sufficient stability and correction of the curvature with preservation of growth. In 2 patients, the instrumentation failed due to upper thoracic sublaminar wire breakage. The ongoing abrasion of the rod-wire interface caused severe metallosis. In these cases, a debridement and revision surgery was performed with partial fusion of the spine. Growth-guidance techniques with sliding metal sublaminar wires seem to be a valuable solution for the preservation of spinal growth in EOS surgery. High curvatures, however, have a higher chance of failure and demand for more corrective strength and support of the instrumentation. The use of metal sublaminar wires in a "sliding" instrumentation can lead to early breakage and metallosis. 4, case series. Surgeons should be aware of possible complications associated with the use of metal laminar wires in spinal fusion and growth-guidance scoliosis surgery. The implementation of materials containing higher fatigue strength and lower friction properties (eg, UHMWPE wires) may avoid these potential complication risks.

Predictive Factors of Graduation Delay in a Medical Program: a Retrospective Cohort Study in Brazil, 2010-2016

Abstract: Introduction: Medical training is a long and expensive process. Admission processes are highly competitive all over the world but being accepted is no guarantee of academic success. Medical school is demanding and stressful, and some students are not able to cope with this new scenario successfully. It is estimated that 10-15% of medical students experience difficulties in adapting to the course, which can lead to academic failure. The identification of predictive factors of failure supports the creation of mechanisms and strategies to avoid course dropout or graduation delay. To identify predictive factors of academic failure in a Brazilian medical program. Methods: A retrospective observational study was carried out with all medical students admitted to a private Brazilian medical school in 2010 and 2011. The main outcome was academic success. Academic failure was defined as graduation delay or course dropout (Group 1), and academic success was defined as graduating within 6 years (Group 2). Sociodemographic and academic data were collected, including grades obtained at the admission process and the first-semester courses. Freshman students and students with passing grades in the first semester (passed students) were analyzed separately. Descriptive and comparative analyses, logistic regression and ROC curve analysis were performed. The level of significance was 0.05. Results: A total of 312 students were admitted during the study period, but 10 were excluded due to lack of information. Of the 302 students included in the study, 105 were included in Group 1 and 197 were included in Group 2. Thirty-two students failed the first semester. The 270 students with passing grades in the first semester were divided into Group 1 (n=73) and Group 2 (n=197). Among the freshman students, lower admission grades were associated with a higher chance of failure (padjusted=0.012). Of the 270 students with passing grades, low academic performance (courses’ mean grades) was associated with graduation delay (padjusted&lt;0.001). Conclusions: Low grades at the admission process (freshman students) and low academic performance in the first semester (students with passing grades) were predictive factors of academic failure.

Left Hemifacial Lymphatic Malformation in a Nine-Year-Old Boy

Left Hemifacial Lymphatic Malformation in a Nine-Year-Old Boy

A directed failure causality network (DFCN) based method for function components risk prioritization under interval type-2 fuzzy environment

Failure risk prioritization of function components plays a key role in the process to redesign a mechanical product. However, the failure causality relationships (FCRs) among failure modes of components are often ignored in the existing design risk assessment methods, leading to inaccurate risk prioritization results. A failure mode in one component can be the cause of a failure mode in another component, and a failure mode with low chance of failure may result in another failure mode with high chance of failure through propagation among failure modes. Thus, the ultimate effects of each failure mode should be determined by considering the effects of failure propagations. In this research, a directed failure causality network (DFCN) model considering FCRs is proposed to describe the FCRs and to predict risks of the designed product. In addition, uncertainties of linguistic terms in evaluation are also considered in the developed model, because linguistic terms are more suitable and natural than quantitative numbers for design engineers to assess design risks based on their knowledge. To describe these uncertainties, interval type-2 fuzzy set is employed to model the designers’ subjective linguistic terms for determining the weights of edges and weights of vertices in the DFCN. A case study for failure risk prioritization of components in redesign of a large tonnage crawler crane (LTCC) is implemented to demonstrate the effectiveness of the proposed method.