NASA Accident Precursor Analysis Handbook, Version 1.0

Catastrophic accidents are usually preceded by precursory events that, although observable, are not recognized as harbingers of a tragedy until after the fact. In the nuclear industry, the Three Mile Island accident was preceded by at least two events portending the potential for severe consequences from an underappreciated causal mechanism. Anomalies whose failure mechanisms were integral to the losses of Space Transportation Systems (STS) Challenger and Columbia had been occurring within the STS fleet prior to those accidents. Both the Rogers Commission Report and the Columbia Accident Investigation Board report found that processes in place at the time did not respond to the prior anomalies in a way that shed light on their true risk implications. This includes the concern that, in the words of the NASA Aerospace Safety Advisory Panel (ASAP), "no process addresses the need to update a hazard analysis when anomalies occur" At a broader level, the ASAP noted in 2007 that NASA "could better gauge the likelihood of losses by developing leading indicators, rather than continue to depend on lagging indicators". These observations suggest a need to revalidate prior assumptions and conclusions of existing safety (and reliability) analyses, as well as to consider the potential for previously unrecognized accident scenarios, when unexpected or otherwise undesired behaviors of the system are observed. This need is also discussed in NASA's system safety handbook, which advocates a view of safety assurance as driving a program to take steps that are necessary to establish and maintain a valid and credible argument for the safety of its missions. It is the premise of this handbook that making cases for safety more experience-based allows NASA to be better informed about the safety performance of its systems, and will ultimately help it to manage safety in a more effective manner. The APA process described in this handbook provides a systematic means of analyzing candidate accident precursors by evaluating anomaly occurrences for their system safety implications and, through both analytical and deliberative methods used to project to other circumstances, identifying those that portend more serious consequences to come if effective corrective action is not taken. APA builds upon existing safety analysis processes currently in practice within NASA, leveraging their results to provide an improved understanding of overall system risk. As such, APA represents an important dimension of safety evaluation; as operational experience is acquired, precursor information is generated such that it can be fed back into system safety analyses to risk-inform safety improvements. Importantly, APA utilizes anomaly data to predict risk whereas standard reliability and PRA approaches utilize failure data which often is limited and rare

Comparison of outcomes in patients undergoing defibrillation threshold testing at the time of implantable cardioverter-defibrillator implantation versus no defibrillation threshold testing

Background: Inability to perform defibrillation threshold (DFT) testing during implantable cardioverter defibrillator (ICD) implantation due to co-morbidities may influence long-term survival. Methods: Retrospective review at The University of Michigan (1999-2004) identified 55 patients undergoing ICD implantation without DFT testing (“No-DFT group”). A randomly selected sample of patients (n = 57) undergoing standard DFT testing (“DFT group”) was compared in terms of appropriate shocks, clinical shock efficacy and all-cause mortality. Results: DFT testing was withheld due to hypotension, atrial fibrillation with inability to exclude left atrial thrombus, left ventricular thrombus, CHF and/or ischemia. The No-DFT group had a similar appropriate shock rate, but lower total survival (69.1% vs. 91.2%, p = 0.004) than the DFT group. The No-DFT group had a higher incidence of ventricular fibrillation (VF) episodes (9.1% vs. 3.1%, p = 0.037), and deaths attributable to VF (3 of 17 deaths vs. 0 of 5 deaths) compared to the DFT group. Multivariate analysis found a trend toward increased risk of death in the No-DFT group (HR 3.18, 95% CI 0.82-12.41, p = 0.095) after adjusting for baseline differences in gender distribution, NYHA class and prior CABG. Conclusions: In summary, overall mortality was higher in the No-DFT group. More deaths attributable to VF occurred in the No-DFT group. Thus, DFT testing should therefore remain the standard of care. Nevertheless, ICD therapy should not be withheld in patients who meet appropriate implant criteria simply on the basis of clinical scenarios that preclude routine DFT testing. (Cardiol J 2007; 14: 463-469

Using the affective priming paradigm to explore the attitudes underlying walking behaviour

Objectives. Walking is poorly represented in memory, making it difficult to measure using self-report and even harder to predict. To circumvent this, we used the affective priming paradigm (Fazio, Sanbonmatsu, Powell, & Kardes, 1986) to assess implicit attitudes towards walking. Methods. Royal Air Force trainee aircraftsmen (N ¼ 188) wore pedometers for 1 week prior to completing the affective priming paradigm, questionnaire and interview. The affective priming paradigm involved a computer-based response latency task containing physical activity words as primes followed by adjectives as targets to be evaluated. Targets were drawn from two bipolar dichotomies, good–bad (the original Fazio et al. items) and happy–sad (mood). Results. Priming for mood items was related to levels of physical activity with high frequency participants priming for the positive (happy) pole and low frequency participants priming for the negative (sad). Both groups primed for the negative element of the Fazio (good–bad) dichotomy. Regarding walking and running, there was no differentiation on the basis of participation level. Instead, facilitated responses to happy targets contrasted with inhibited responses to sad targets for both types of locomotion. There was weak evidence that intentions to run were associated with priming of positive target items, irrespective of category. Conclusions. The relationship between implicit attitudes and behaviour is complex. Whereas implicit attitudes were related to overall exercise participation, they were not related to the specific activity of walking, despite the behaviour being mainly under automatic control.</p

Porównanie wyników leczenia u pacjentów poddawanych lub niepoddawanych ocenie progu defibrylacji w czasie wszczepienia kardiowertera-defibrylatora

Wstęp: Brak możliwości przeprowadzenia oceny progu defibrylacji (DFT) podczas implantacji kardiowertera-defibrylatora (ICD) ze względu na występowanie współistniejących chorób może wpływać na przeżywalność w obserwacji odległej. Metody: W retrospektywnym przeglądzie przeprowadzonym na University of Michigan (1999-2004) zidentyfikowano 55 pacjentów, u których przeprowadzono implantację ICD bez oceny DFT. Grupę tą porównano pod względem występowania uzasadnionych wyładowań, ich klinicznej skuteczności oraz całkowitej śmiertelności z losowo wybraną grupą osób (n = 57), u których przeprowadzono standardową ocenę DFT. Wyniki: Oceny DFT nie dokonywano z powodu niskiej wartości ciśnienia tętniczego, migotania przedsionków z niemożnością wykluczenia skrzepliny w lewym przedsionku, skrzepliny w lewej komorze, zastoinowej niewydolności serca i/lub niedokrwienia. W grupie bez oceny DFT liczba uzasadnionych wyładowań była podobna, natomiast łączne przeżycie mniejsze (69,1% vs. 91,2%; p = 0,004) niż w grupie poddawanej ocenie DFT. W grupie bez oceny DFT stwierdzono większą częstość incydentów migotania komór (VF; 9,1% vs. 3,1%; p = 0,037) i zgonów z powodu VF (3 spośród 17 zgonów vs. 0 spośród 5 zgonów) ni&#191; w grupie poddawanej ocenie DFT. W analizie wielozmiennej wykazano trend w kierunku zwiększonego ryzyka zgonów w grupie bez oceny DFT [iloraz hazardu (HR) 3,18; 95% przedział ufności (CI) 0,82&#8211;12,41; p = 0,095] po uwzględnieniu początkowych różnic rozkładu płci, klasy czynnościowej według Nowojorskiego Towarzystwa Kardiologicznego (NYHA) oraz wcześniejszego pomostowania tętnic wieńcowych. Wnioski: Całkowita śmiertelność była większa w grupie bez oceny DFT, gdzie wystąpiło więcej zgonów, które można było przypisywać VF. Ocena DFT powinna więc pozostać standardem postępowania. Mimo to nie należy rezygnować z leczenia za pomocą ICD u pacjentów, którzy spełniają kryteria implantacji, jeżeli jedynym powodem tego miałoby być występowanie sytuacji klinicznych wykluczających ocenę DFT

A Population of X-ray Weak Quasars: PHL 1811 Analogs at High Redshift

We report the results from Chandra and XMM-Newton observations of a sample of 10 type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were identified by the Sloan Digital Sky Survey at high redshift (z~2.2); eight are radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811 analogs are notably X-ray weak by a mean factor of ~13. These sources lack broad absorption lines and have blue UV/optical continua, suggesting they are intrinsically X-ray weak. However, their average X-ray spectrum appears to be harder than those of typical quasars, which may indicate the presence of heavy intrinsic X-ray absorption. Our radio-quiet PHL 1811 analogs support a connection between an X-ray weak spectral energy distribution and PHL 1811-like UV emission lines; this connection provides an economical way to identify X-ray weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the radio-quiet quasar population is estimated to be < 1.2%. We have investigated correlations between relative X-ray brightness and UV emission-line properties for a sample combining radio-quiet PHL 1811 analogs, PHL 1811, and typical type 1 quasars. These correlation analyses suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions. Observationally, radio-quiet PHL 1811 analogs appear to be a subset (~30%) of radio-quiet weak-line quasars. The existence of a subset of quasars in which high-ionization "shielding gas" covers most of the BELR, but little more than the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two radio-intermediate PHL 1811 analogs are X-ray bright. One of them appears to have jet-dominated X-ray emission, while the nature of the other remains unclear.Comment: ApJ accepted; 25 pages, 11 figures and 8 table

Report of Third Annual Seminar on Estate Planning

Reports from the UK/CLE Third Annual Seminar on Estate Planning held July 23-24, 1976

A Profile Likelihood Analysis of the Constrained MSSM with Genetic Algorithms

The Constrained Minimal Supersymmetric Standard Model (CMSSM) is one of the simplest and most widely-studied supersymmetric extensions to the standard model of particle physics. Nevertheless, current data do not sufficiently constrain the model parameters in a way completely independent of priors, statistical measures and scanning techniques. We present a new technique for scanning supersymmetric parameter spaces, optimised for frequentist profile likelihood analyses and based on Genetic Algorithms. We apply this technique to the CMSSM, taking into account existing collider and cosmological data in our global fit. We compare our method to the MultiNest algorithm, an efficient Bayesian technique, paying particular attention to the best-fit points and implications for particle masses at the LHC and dark matter searches. Our global best-fit point lies in the focus point region. We find many high-likelihood points in both the stau co-annihilation and focus point regions, including a previously neglected section of the co-annihilation region at large m_0. We show that there are many high-likelihood points in the CMSSM parameter space commonly missed by existing scanning techniques, especially at high masses. This has a significant influence on the derived confidence regions for parameters and observables, and can dramatically change the entire statistical inference of such scans.Comment: 47 pages, 8 figures; Fig. 8, Table 7 and more discussions added to Sec. 3.4.2 in response to referee's comments; accepted for publication in JHE

Natural Knowledge, Inc.: The Royal Society as a Metropolitan Corporation

This article attempts to think through the logic and distinctiveness of the early Royal Society's position as a metropolitan knowledge community and chartered corporation, and the links between these aspects of its being. Among the knowledge communities of Restoration London it is one of the best known and most studied, but also one of the least typical and in many respects one of the least coherent. It was also quite unlike the chartered corporations of the City of London, exercising almost none of their ordinary functions and being granted very limited power and few responsibilities. I explore the society's imaginative and material engagements with longer-established corporate bodies, institutions and knowledge communities, and show how those encounters repeatedly reshaped the early society's internal organization, outward conduct and self-understanding. Building on fundamental work by Michael Hunter, Adrian Johns, Lisa Jardine and Jim Bennett, and new archival evidence, I examine the importance of the city to the society's foundational rhetoric and the shifting orientation of its search for patronage, the development of its charter, and how it learned to interpret the limits and possibilities of its privileges through its encounters with other chartered bodies, emphasizing the contingent nature of its early development