Specific Causes Of Failure Research Articles

Technical Adequacy of Fully Automated Artificial Intelligence Body Composition Tools: Assessment in a Heterogeneous Sample of External CT Examinations.

BACKGROUND. Clinically usable artificial intelligence (AI) tools analyzing imaging studies should be robust to expected variations in study parameters. OBJECTIVE. The purposes of this study were to assess the technical adequacy of a set of automated AI abdominal CT body composition tools in a heterogeneous sample of external CT examinations performed outside of the authors' hospital system and to explore possible causes of tool failure. METHODS. This retrospective study included 8949 patients (4256 men, 4693 women; mean age, 55.5 ± 15.9 years) who underwent 11,699 abdominal CT examinations performed at 777 unique external institutions with 83 unique scanner models from six manufacturers with images subsequently transferred to the local PACS for clinical purposes. Three independent automated AI tools were deployed to assess body composition (bone attenuation, amount and attenuation of muscle, amount of visceral and sub-cutaneous fat). One axial series per examination was evaluated. Technical adequacy was defined as tool output values within empirically derived reference ranges. Failures (i.e., tool output outside of reference range) were reviewed to identify possible causes. RESULTS. All three tools were technically adequate in 11,431 of 11,699 (97.7%) examinations. At least one tool failed in 268 (2.3%) of the examinations. Individual adequacy rates were 97.8% for the bone tool, 99.1% for the muscle tool, and 98.9% for the fat tool. A single type of image processing error (anisometry error, due to incorrect DICOM header voxel dimension information) accounted for 81 of 92 (88.0%) examinations in which all three tools failed, and all three tools failed whenever this error occurred. Anisometry error was the most common specific cause of failure of all tools (bone, 31.6%; muscle, 81.0%; fat, 62.8%). A total of 79 of 81 (97.5%) anisometry errors occurred on scanners from a single manufacturer; 80 of 81 (98.8%) occurred on the same scanner model. No cause of failure was identified for 59.4% of failures of the bone tool, 16.0% of failures of the muscle tool, or 34.9% of failures of the fat tool. CONCLUSION. The automated AI body composition tools had high technical adequacy rates in a heterogeneous sample of external CT examinations, supporting the generalizability of the tools and their potential for broad use. CLINICAL IMPACT. Certain causes of AI tool failure related to technical factors may be largely preventable through use of proper acquisition and reconstruction protocols.

Doubly-robust estimator of the difference in restricted mean times lost with competing risks data.

In the context of competing risks data, the subdistribution hazard ratio has limited clinical interpretability to measure treatment effects. An alternative is the difference in restricted mean times lost (RMTL), which gives the mean time lost to a specific cause of failure between treatment groups. In non-randomized studies, the average causal effect is conventionally used for decision-making about treatment and public health policies. We show how the difference in RMTL can be estimated by contrasting the integrated cumulative incidence functions from a Fine-Gray model. We also show how the difference in RMTL can be estimated by using inverse probability of treatment weighting and contrasts between weighted non-parametric estimators of the area below the cumulative incidence. We use pseudo-observation approaches to estimate both component models and we integrate them into a doubly-robust estimator. We demonstrate that this estimator is consistent when either component is correctly specified. We conduct simulation studies to assess its finite-sample performance and demonstrate its inherited consistency property from its component models. We also examine the performance of this estimator under varying degrees of covariate overlap and under a model misspecification of nonlinearity. We apply the proposed method to assess biomarker-treatment interaction in subpopulations of the POPLAR and OAK randomized controlled trials of second-line therapy for advanced non-small-cell lung cancer.

Causes of failure among Malaysian female entrepreneurs

PurposeThis paper aims to explore the specific causes of failure among Malaysian female entrepreneurs who were provided with financial services by the microfinance institution: Amanah Ikhtiar Malaysia (AIM) to start up their own businesses.Design/methodology/approachThis paper adopts a qualitative-based case study design approach, with data collected from a total of 18 female entrepreneurs who had failed to develop their businesses. In-depth personal interviews were conducted, coupled with personal observation via purposive cum snowball sampling.FindingsThematic analysis revealed a pattern-based outcome which discloses a variety of causes affecting the failure of Malaysian female entrepreneurship. These causes ranged from inter-related external factors which were perceived as beyond their control, such as personal life events, intensive competition and loan inflexibility to internal causes, which were related to lack of resources, poor financial management and personal dissatisfaction with their own business performance.Research limitations/implicationsThe findings of this study provide valuable information for Malaysian economic policymakers in how to practically address the objectives of the National Women's Policy (NPW) and improve the innovative quality of their products and services. A thorough understanding of the specific obstacles facing female entrepreneurs in Malaysia is essential if policymakers are to improve opportunity exploitation efficiency and assist in mitigating the external and internal causes of business failure among Malaysian females.Originality/valueStudies in this field have demonstrated that most new “start-ups” fail within three years of their establishment. While determinist, emotive and voluntarist theories can often provide an adequate explanation for the causes of business failure, it is clear that no single factor is usually responsible. Rather, multiple interrelated factors are found to be at play. This study, therefore, provides an integrative model for causes of business failure among small-business female entrepreneurs. It also represents one of only a few such studies in the literature and, to the best of knowledge at the time of writing, is the first such study that used an integrative approach to explain the causes of business failure in the Malaysian context.

Analysis of the factors involved in procedural failure: Endoscopic retrograde cholangiopancreatography using a short-type single-balloon enteroscope for patients with surgically altered gastrointestinal anatomy.

To analyze factors involved in procedural failure and to discuss responses to procedural failure by using the outcomes of endoscopic retrograde cholangiopancreatography (ERCP) carried out using a short-type single-balloon enteroscope (short SBE) in patients with surgically altered gastrointestinal anatomy. The study sample included patients who underwent ERCP-related procedures using a short SBE between September 2011 and September 2018 at our hospital. Outcomes, including procedural success rate, were studied retrospectively to analyze the factors involved in procedural failure. Analysis included 191 procedures carried out in 121 patients. Procedural success rate was 85.9% with an adverse event rate of 8.4%. Causes of procedural failure included malignant biliary obstruction (odds ratio [OR] 2.89, 95% confidence interval [CI] 1.19-7.25, P=0.02), first ERCP attempt (OR: 5.32, 95% CI: 1.30-36.30, P=0.02), and Roux-en-Y reconstruction (OR: 0.08, 95% CI: 0.004-0.39, P<0.001). With regard to the response to failure, in cases of malignant biliary obstruction, reattempted short SBE-assisted ERCP was difficult because of invasion of the small intestine or papilla. A large number of these cases required alternative treatment (10 of 15 cases, 66.7%) using percutaneous transhepatic biliary drainage (PTBD) or endoscopic ultrasound-guided biliary drainage (EUS-BD). Endoscopic retrograde cholangiopancreatography using a short SBE is safe and effective, with malignant biliary obstruction being a specific cause of failure. Technical proficiency with different modalities, such as PTBD and EUS-BD, is necessary to respond to failure in these cases.

Firm age dynamics and causes of corporate bankruptcy: age dependent explanations for business failure

Theories of organizational failure predict that reasons for corporate demise may differ by firm age and life cycle stage. However, large-scale empirical studies that investigate the relationship between firm characteristics and specific causes of failure are scarce. This study therefore aims to shed light on firm mortality and firm age by analyzing a unique data set of bankrupt small and medium-sized enterprises. Separate statistical models for individual causes of failure are developed in which the liabilities of age are abstracted and disentangled from liabilities of size and industry specific variables on firm level. In this regard organizational ecology argumentation is integrated with resource-based view reasoning following the call for multi-theoretic approaches in organizational failure research. Results show that different failure causes dominate at specific stages of organizational life as defined by age quartiles. While young and adolescent firms predominantly fail due to internal shortcomings, mature small and medium-sized enterprises struggle more with increased competition and economic slowdowns.

Statistical Inference for Power-Law Process With Competing Risks

The focus of this article is on failure history of a repairable system for which the relevant data comprise successive event times for a recurrent phenomenon along with an event-count indicator. We undertake an investigation for analyzing failures from repairable systems that are subject to multiple failure modes. Failure data representing a cluster of recurrent events from a single system are studied under the parametric framework of a power-law process, a model that has found considerable attention in industrial applications. Some interesting and nonstandard asymptotic results ensue in this context that are discussed in detail. Extensive simulation has been carried out that supplements the theoretical findings. An extension to the case where the specific cause of failure may be missing is investigated in detail. The methodology has been implemented on recurrent failure data obtained from a warranty claim database for a fleet of automobiles. Supplementary material for this article is available online.

Brain protein oxidation: what does it reflect?

Antioxidant neuroprotection: Since the elaboration of the concept of oxidative stress in the 1980s, the idea that this phenomenon may be particularly involved in diseases of the brain has become widely accepted (Halliwell, 2006). Embedded in the framework of neuroprotection, the investigation of antioxidant strategies was fuelled by the repeated observation of redox dysregulation and outright oxidative damage on the molecular scale in many chronic and acute conditions involving neuronal dysfunction (Moosmann and Behl, 2002). In fact, different approaches of pharmacological antioxidant neuroprotection worked surprisingly well in animal studies; however, they have so far refused to work, almost without exception, in the clinic. The failure of NXY-059 in 2007, which was the latest candidate in a series of substances tested for ischemic stroke, was a disturbing setback in this respect (Shuaib et al., 2007). The very obvious discrepancy between success rates in mice, rats and humans had not been anticipated, as many drugs based neuronal receptor pharmacology had found their ready translation from animal studies into the clinic. What might have been the specific causes of failure when it comes to antioxidant neuroprotection?

Reliability Analysis of Pressure Meter Electronic System Based on Fault Tree

Pressure meter is an important testing and storage investment during oilfield hydraulic fracturing. The pressure meter electronic system mainly composed by the microcontroller module, battery module, temperature signal acquisition and processing module, the pressure signal acquisition and processing module and memory module. This paper briefly introduced the principle of pressure meter, and established fault tree based on schematic diagram of pressure meter electronic system and specific cause of failure; Aiming at solving traditional reliability analysis the limitation of long cycle and poor economy, the paper adopt reliability simulation by using MATLAB and combined with the theory of Monte Carlo. Ultimately,getting the reliability curve and life of pressure meter electronic system. The reliability of electronic systems gradually decreases with increasing time and obeyed exponentially distributed law; Electronic system simulation life of 2877.7 hours. In other words, the electronic system can work 2877.7 hours since down to underground of oil well. It has some guidance for engineering practice, as well as provides a measure of reliability analysis for pressure meter electronic system.

Principles and techniques in revision total knee arthroplasty

Description: This book describes the principles and modern operative techniques used in revision total knee arthroplasty, and builds on the excellent AAOS series. The authors are well published in the field of revision arthroplasty, and each contributes their wealth of knowledge to this amazing book. It consists of 119 pages and 132 pictures, is very well referenced and has an excellent literature base. The book starts with a chapter on the basic principles, establishing a very good evidence-based foundation that will enable surgeons and residents to make sound decisions and proceed with confidence. The following two chapters detail pre-operative planning and surgical exposures, and direct surgeons towards the best ways to plan their arthroplasty. The subsequent chapters go on to explain implant selection and the management of specific causes of failure. There is an abundance of pearls and recent literature to support the decision making processes and operative techniques.

An assessment of failure of building components in Nigeria

Building collapse is usually an outcome of progressive deterioration of the various components forming the building unit. This paper identified and assessed the nature and sources of both the generic and specific causes of failure of building components in Nigeria. Osun State was purposively sampled for the study. Data were obtained through use of a structured questionnaire, and results were analysed using a relative importance index. Analysis showed that building components tend to fail at different rates depending on the materials, designs, method of construction, environmental conditions and the use to which the building is put. Substandard materials and design errors were identified as major causes of component failure. The specific causes of failure of building components, apart from substandard materials and design errors, relate primarily to construction method and the use of the various components.

Nonparametric estimation of bivariate survivor function under masked causes of failure

Consider a system that consists of k components. Each component is subject to more than one cause of failure. Due to inadequacy in the diagnostic mechanism or reluctance to report any specific cause of failure (disease), the exact cause of failure cannot be identified easily. In such situations, where the cause of failure is masked, test procedures restrict the cause of failure to a set of possible types containing the true failure cause. In this paper, we develop a nonparametric estimator for the bivariate survivor function of competing risk models under masked causes of failure based on the vector hazard rate. Asymptotic properties of the estimator are established. A simulation study is carried out to assess the performance of the estimator. We also illustrate the method with a data set.

Factors affecting success and failure of trickle irrigation systems in Balochistan, Pakistan

An evaluation of performance of trickle irrigation systems installed in Balochistan, Pakistan during 1982–2002 was conducted by field surveys, physical verifications and interviews with farmers. Thirty systems were fully or partially operational and 76 had been abandoned. Successful systems required clean and reliable water supply, availability of spare components and accessories for replacements, skilled manpower, and a high level of interest and participation by the owner. The dominant species irrigated with these trickle systems were apples, grapes, and mixed orchards. Installations of trickle systems on old mature orchards were not generally successful due to lack of adaptation of the new system to limited and scheduled irrigation supplies. Many of the irrigators were not instructed on how to adjust the trickle system to meet changing needs of the plants. Consequently, growth of some of the trees was stunted and a few of them died. Lack of technical skill to repair and maintain the system and non-availability of replacement parts were general causes of failure of installed trickle irrigation systems. Clogging of the emitters was the primary specific cause of failure. Emitters with a larger opening that will not be clogged by most of the contaminants contained in the water available to these farmers and turbulent action screening systems to take out the other contaminants are proposed as solutions to this problem. Commercial shops, which sell the components, carry replacement parts and provide after-sales service are needed to keep trickle systems functioning in these isolated areas.

Misspecified regression model for the subdistribution hazard of a competing risk

We consider a competing risks setting, when evaluating the prognostic influence of an exposure on a specific cause of failure. Two main regression models are used in such analyses, the Cox cause-specific proportional hazards model and the subdistribution proportional hazards model. They are exemplified in a real data example focusing on relapse-free interval in acute leukaemia patients. We examine the properties of the estimator based on the latter model when the true model is the former. An explicit relationship between subdistribution hazards ratio and cause-specific hazards ratio is derived, assuming a flexible parametric distribution for latent failure times.

On the NBU ageing notion within the competing risks model

The classical competing risks model deals with failure times of items subject to multiple causes of failure. We propose a version of the well-known ‘new better than used’ and ‘new worse than used’ ageing notions for random lifetimes within a specific cause of failure in the competing risks set up. Various properties of these new notions are studied, including the closure under time-dependent scale changes, as well as their connection to the hazard rate functions of the competing risks model. A data analytic example is finally provided.

Clinical success of cast metal posts and cores

The topic of posts for endodontically treated teeth has received considerable attention in the literature, but there is sparse in vivo research and certain information from in vitro investigations is contradictory. A retrospective study of 1273 endodontically treated teeth in the practices of nine dentists in general practice indicated an inordinately high failure rate with cast posts and cores compared with alternate systems of coronoradicular stabilization. However, a closer evaluation of the data in this study indicated that almost half of the cast posts were half the desired length or less. The indications for the cast post and core are discussed and the specific causes of failure are reviewed. Additional research is needed to compare the success rate of securely seated cast posts and cores with alternate methods of coronoradicular stabilization.

Revision stapedectomy surgery.

Eighty-two revision stapedectomies were analyzed to determine causes of primary and revision stapedectomy failure. The specific cause of failure can often be anticipated preoperatively by analysis of the patient's audiogram, symptoms, type of prosthesis initially used, and the duration of time between initial surgery and the onset of symptoms. Guidelines for performance of revision stapedectomy are discussed.