Planning the Unplanned Experiment: Towards Assessing the Efficacy of Standards for Safety-Critical Software

While software in industries such as aviation has a good safety record, little is known about whether standards for software in other safety-critical applications “work” — or even what that means. Safe use of software in safety-critical applications requires well-founded means of determining whether the software is fit for such use. It is often implicitly argued that software is fit for safety-critical use because it conforms to an appropriate standard. Without knowing whether a standard “works,” such reliance is an experiment and without carefully collecting assessment data, that experiment is unplanned. To help “plan” the experiment, we organized a workshop to develop practical ideas for assessing software safety standards. In this paper, we relate and elaborate on our workshop discussion, which revealed subtle, but important, study design considerations and practical barriers to collecting appropriate historical data and recruiting appropriate experimental subjects. We discuss assessing standards as written and as applied, several candidate definitions for what it means for a standard to “work,” and key assessment strategies and study techniques. Finally, we conclude with a discussion of the kinds of research that will be required and how academia, industry and regulators might collaborate to overcome these noted barriers

“How could this happen to us?” French Community and Sault Ste. Marie’s English Resolution

In January, 1990 Sault Ste. Marie, Canada, a northern city with over 200 hundred years of French settlement, passed a resolution declaring its city government would operate in English-only. Accounts of how this language specific resolution came about are often, even inescapably overshadowed by the character and actions of the city’s brash, defiant Mayor, Joe Fratesi. This paper presents an expanded account of events, wherein Mayor Fratesi is one of many actors, albeit one ready to maximize a political opportunity. To existing accounts, this paper adds the voices and experiences of those within the French community, ones largely absent in the published record. While those outside the Sault saw the resolution as threatening to Canada’s linguistic and cultural aspirations, within the Sault it was clearly a local matter

An Investigation of Proposed Techniques for Quantifying Confidence in Assurance Arguments

The use of safety cases in certification raises the question of assurance argument sufficiency and the issue of confidence (or uncertainty) in the argument's claims. Some researchers propose to model confidence quantitatively and to calculate confidence in argument conclusions. We know of little evidence to suggest that any proposed technique would deliver trustworthy results when implemented by system safety practitioners. Proponents do not usually assess the efficacy of their techniques through controlled experiment or historical study. Instead, they present an illustrative example where the calculation delivers a plausible result. In this paper, we review current proposals, claims made about them, and evidence advanced in favor of them. We then show that proposed techniques can deliver implausible results in some cases. We conclude that quantitative confidence techniques require further validation before they should be recommended as part of the basis for deciding whether an assurance argument justifies fielding a critical system

Planning the Unplanned Experiment: Assessing the Efficacy of Standards for Safety Critical Software

We need well-founded means of determining whether software is t for use in safety-critical applications. While software in industries such as aviation has an excellent safety record, the fact that software aws have contributed to deaths illustrates the need for justi ably high con dence in software. It is often argued that software is t for safety-critical use because it conforms to a standard for software in safety-critical systems. But little is known about whether such standards `work.' Reliance upon a standard without knowing whether it works is an experiment; without collecting data to assess the standard, this experiment is unplanned. This paper reports on a workshop intended to explore how standards could practicably be assessed. Planning the Unplanned Experiment: Assessing the Ecacy of Standards for Safety Critical Software (AESSCS) was held on 13 May 2014 in conjunction with the European Dependable Computing Conference (EDCC). We summarize and elaborate on the workshop's discussion of the topic, including both the presented positions and the dialogue that ensued

A Drosophila melanogaster model of spinal muscular atrophy reveals a function for SMN in striated muscle

Mutations in human survival motor neurons 1 (SMN1) cause spinal muscular atrophy (SMA) and are associated with defects in assembly of small nuclear ribonucleoproteins (snRNPs) in vitro. However, the etiological link between snRNPs and SMA is unclear. We have developed a Drosophila melanogaster system to model SMA in vivo. Larval-lethal Smn-null mutations show no detectable snRNP reduction, making it unlikely that these animals die from global snRNP deprivation. Hypomorphic mutations in Smn reduce dSMN protein levels in the adult thorax, causing flightlessness and acute muscular atrophy. Mutant flight muscle motoneurons display pronounced axon routing and arborization defects. Moreover, Smn mutant myofibers fail to form thin filaments and phenocopy null mutations in Act88F, which is the flight muscle–specific actin isoform. In wild-type muscles, dSMN colocalizes with sarcomeric actin and forms a complex with α-actinin, the thin filament crosslinker. The sarcomeric localization of Smn is conserved in mouse myofibrils. These observations suggest a muscle-specific function for SMN and underline the importance of this tissue in modulating SMA severity

Transcatheter or surgical aortic-valve replacement in intermediate-risk patients

BACKGROUND: Previous trials have shown that among high-risk patients with aortic stenosis, survival rates are similar with transcatheter aortic-valve replacement (TAVR) and surgical aorticvalve replacement. We evaluated the two procedures in a randomized trial involving intermediate-risk patients. METHODS: We randomly assigned 2032 intermediate-risk patients with severe aortic stenosis, at 57 centers, to undergo either TAVR or surgical replacement. The primary end point was death from any cause or disabling stroke at 2 years. The primary hypothesis was that TAVR would not be inferior to surgical replacement. Before randomization, patients were entered into one of two cohorts on the basis of clinical and imaging findings; 76.3% of the patients were included in the transfemoral-access cohort and 23.7% in the transthoracic-access cohort. RESULTS: The rate of death from any cause or disabling stroke was similar in the TAVR group and the surgery group (P=0.001 for noninferiority). At 2 years, the Kaplan–Meier event rates were 19.3% in the TAVR group and 21.1% in the surgery group (hazard ratio in the TAVR group, 0.89; 95% confidence interval [CI], 0.73 to 1.09; P=0.25). In the transfemoralaccess cohort, TAVR resulted in a lower rate of death or disabling stroke than surgery (hazard ratio, 0.79; 95% CI, 0.62 to 1.00; P=0.05), whereas in the transthoracic-access cohort, outcomes were similar in the two groups. TAVR resulted in larger aortic-valve areas than did surgery and also resulted in lower rates of acute kidney injury, severe bleeding, and new-onset atrial fibrillation; surgery resulted in fewer major vascular complications and less paravalvular aortic regurgitation. CONCLUSIONS: In intermediate-risk patients, TAVR was similar to surgical aortic-valve replacement with respect to the primary end point of death or disabling stroke. (Funded by Edwards Lifesciences; PARTNER 2 ClinicalTrials.gov number, NCT01314313

Sources of resiliency among successful foster youth

In this study, 44 young adults who were removed from their biological parents as children responded to survey questions about the internal and external resources that helped them to "beat the odds" and, unlike most foster youth, complete a post-secondary educational program or achieve at least junior standing in a four-year institution. The results indicated that the majority of these youth acknowledge the presence of a variety of protective factors, including a sense of competence, goals for the future, social support, and involvement in community service activities. Implications for the improvement of foster youth services include the enhancement of programs that nourish supportive relationships with caring adults and enable youth to positively contribute by helping others.Foster youth Resiliency

Hiding in plain sight: combining field-naturalist observations and herbarium records to reveal phenological change

As the climate warms, northern ecosystems are experiencing warmer winters and seasonal climatic shifts. Vascular plants are expected to respond to climate change by adjusting flowering or seeding periods. To determine how a native mixed-wood boreal floral assemblage has responded to warming temperatures over the 20th century, we collated historical observations made by field-naturalists as well as voucher data from the Thunder Bay region of Ontario, Canada. Combining these datasets, we performed regression analyses on 11 species of spring-flowering vascular plants to evaluate temporal trends and used spring cumulative growing degree day (sGDD0) to determine the influence of climate on flowering times. Four species showed consistent positive temporal trends (i.e., flowered later with time), while four species (three of which also demonstrated temporal trends) showed negative trends with sGDD0 (i.e., flowered earlier with an increased number of degree days above 0°C). The unexpected observation of later flowering times but predicted observation of earlier blooming with increased sGDD0 indicates that the inclusion of climate metrics may be necessary to determine the response of native vascular plants to the onset of changes in their environment. These observations were not statistically significant when field-naturalist or herbarium voucher data were analyzed separately, possibly due to low statistical power. Combining data from both sources, however, revealed common responses to climate warming among species within an ecoregion

Applying Augmented Reality Technology To Improve Lunar Extravehicular Activity Operations

Embry-Riddle Aeronautical University’s Spacesuit Utilization of Innovative Technology Laboratory (ERAU S.U.I.T. Lab) has developed an augmented reality (AR) heads up display, Augmented Lunar Exploration and Extravehicular Interface (ALEXEI), for lunar astronauts as part of the 2021 NASA SUITS challenge. The challenge encourages students to explore and develop potential interfaces to aid astronauts as NASA’s Artemis Program prepares for the return to the lunar surface. The system runs on the Magic Leap One AR headset, and uses a tactile controller combined with head tracking for the primary form of input. ALEXEI organizes EVA information into two screens located on the periphery of the user and separates the EVA core features into separate applications that satisfy the challenge’s requirements. These applications include Vitals, Tasks, Navigation, Science, Settings, and Media. The ALEXEI system underwent limited human in the loop testing at ERAU and was accepted to be tested at NASA’s Johnson Space Center. EVA experts demoed, evaluated, and provided positive feedback of the overall system. Standout features included the multiple navigational aids, user customization, and tactile control input system. To sum-up ALEXEI’s core design has been approved as an exceptional proof of concept to help improve situational awareness for future EVAs