Reuse of safety certification artefacts across standards and domains: A systematic approach

Reuse of systems and subsystem is a common practice in safety-critical systems engineering. Reuse can improve system development and assurance, and there are recommendations on reuse for some domains. Cross-domain reuse, in which a previously certified product typically needs to be assessed against different safety standards, has however received little attention. No guidance exists for this reuse scenario despite its relevance in industry, thus practitioners need new means to tackle it. This paper aims to fill this gap by presenting a systematic approach for reuse of safety certification artefacts across standards and domains. The approach is based on the analysis of the similarities and on the specification of maps between standards. These maps are used to determine the safety certification artefacts that can be reused from one domain to another and reuse consequences. The approach has been validated with practitioners in a case study on the reuse of an execution platform from railway to avionics. The results show that the approach can be effectively applied and that it can reduce the cost of safety certification across standards and domains. Therefore, the approach is a promising way of making cross-domain reuse more cost-effective in industry.European Commission's FP7 programm

Matched cohort study on the efficacy of tocilizumab in patients with COVID-19

Background: Tocilizumab has been proposed as a treatment for the new disease COVID-19, however, there is not enough scientific evidence to support this treatment. The objective of this study is to analyze whether the use of tocilizumab is associated with respiratory improvement and a shorter time to discharge in patients with COVID-19 and lung involvement. Methods: Observational study on a cohort of 418 patients, admitted to three county hospitals in Catalonia (Spain). Patients admitted consecutively were included and followed until discharge or up to 30 days of admission. A sub-cohort of patients treated with tocilizumab and a sub-cohort of control patients were identified, matched by a large number of risk factors and clinical variables. Sub-cohorts were also matched by the number of other treatments for COVID-19 that patients received. Increment in SAFI (inspired oxygen fraction / saturation) 48 h after the start of treatment, and time to discharge, were the primary outcomes. Mortality, which was a secondary outcome, was analyzed in the total cohort, by using logistic regression models, adjusted by confounders. Results: There were 96 patients treated with tocilizumab. Of them, 22 patients could be matched with an equivalent number of control patients. The increment in SAFI from baseline to 48 h of treatment, was not significantly different between groups (tocilizumab: −0.04; control: 0.09; p = 0.636). Also, no difference in time to discharge was found between the two sub-cohorts (logrank test: p = 0.472). The logistic regression models, did not show an effect of tocilizumab on mortality (OR 0.99; p = 0.990). Conclusions: We did not find a clinical benefit associated with the use tocilizumab, in terms of respiratory function at 48 h of treatment, or time to discharge

Choice of mode of transport for long-distance trips: Solving the problem of sparse data

Transport planning is usually based on models’ forecasts, but the reliability of their outputs depends so much on the quality of input-data they are fed with. Discrete-choice models are used to characterise travellers’ behaviour in choosing their transport mode. Their calibration process is usually based on data stemming from household survey campaigns. However, the modelling in multimodal and intermodal transport on an interurban level is far more complicated and costly than in the case of an urban area. An alternative way to reduce costs is achieved by designing a choice-based sampling strategy where household surveys are replaced by specific surveys for each transport mode. This strategy generates a non-random sample that has to be treated correctly during the estimation process. In principle, the sample does not represent population market quotas for each different transport option. Moreover, as a result of both physical and functional constraints, the survey period cannot cover all origin–destination pairs (O–D pairs) in an optimal way and, consequently, the above-mentioned bias also affects each different individual O–D pair or, at least, group of pairs. In order to overcome this problem, this study presents a new procedure derived from the introduction of maximum likelihood estimators. These estimators assume the original mode options in terms of population quotas and in terms of O–D groups of pairs. The procedure is based on the optimisation of an objective-function to correct the above-mentioned bias in a way similar to the estimators of samples based on different choice options. The method named DWELT estimates the parameters corresponding to each explanatory variable using mode shares for each O–D pair or group of pairs. DWELT has been successfully validated in the case study of the Madrid–Barcelona interurban corridor in Spain. This result allows to achieve a more flexible cheaper survey procedure for interurban transport planning activities. Therefore transport policy strategies could be better designed and tested with lower costs

Choice of mode of transport for long-distance trips: Solving the problem of sparse data

Transport planning is usually based on models' forecasts, but the reliability of their outputs depends so much on the quality of input-data they are fed with. Discrete-choice models are used to characterise travellers' behaviour in choosing their transport mode. Their calibration process is usually based on data stemming from household survey campaigns. However, the modelling in multimodal and intermodal transport on an interurban level is far more complicated and costly than in the case of an urban area. An alternative way to reduce costs is achieved by designing a choice-based sampling strategy where household surveys are replaced by specific surveys for each transport mode. This strategy generates a non-random sample that has to be treated correctly during the estimation process. In principle, the sample does not represent population market quotas for each different transport option. Moreover, as a result of both physical and functional constraints, the survey period cannot cover all origin-destination pairs (O-D pairs) in an optimal way and, consequently, the above-mentioned bias also affects each different individual O-D pair or, at least, group of pairs. In order to overcome this problem, this study presents a new procedure derived from the introduction of maximum likelihood estimators. These estimators assume the original mode options in terms of population quotas and in terms of O-D groups of pairs. The procedure is based on the optimisation of an objective-function to correct the above-mentioned bias in a way similar to the estimators of samples based on different choice options. The method named DWELT estimates the parameters corresponding to each explanatory variable using mode shares for each O-D pair or group of pairs. DWELT has been successfully validated in the case study of the Madrid-Barcelona interurban corridor in Spain. This result allows to achieve a more flexible cheaper survey procedure for interurban transport planning activities. Therefore transport policy strategies could be better designed and tested with lower costs.

4th Workshop on Systems Testing and Validation 2006: 30th March 2006, Potsdam, Germany; Proceedings; In conjunction with 13th Annual IEEE International Conference and Workshop on the Engineering of Computer Based Systems (ECBS)

The need to count on trusted systems is growing day by day. Together with traditional domains such as medical devices, automotive, railway, aeronautical, space and telecommunications, new applications and services are coming up everyday. Terms such as ubiquitous, pervasive, or autonomic computing, products under the general umbrella of smart devices or the use of large wireless sensors networks indicate a clear trend in the increase of application complexity and dependency. Our daily life dependability on computers and computer systems is growing at a high rate, and validation is gaining importance at the same rate. To perform a proper validation process encounters a number of problems both from a technical and from a managerial point of view, also considering that the complexity of the underlying software is growing as well. As a consequence inputs from research contributions and experience from industry are required in order to enable innovative, and often more rigorous, approaches. The System Testing and Validation Workshop is a series of events initiated in the year 2002 and seeks to provide answers to the many open issues related to validation

Circumferential skin creases, cleft palate, typical face, intellectual disability and growth delay: "Circumferential skin creases Kunze type"

Congenital symmetrical circumferential skin creases are a rare feature, often described as the "Michelin Tire Baby" syndrome and in general having a good prognosis. In some patients however, the circumferential skin creases are associated with other congenital malformations. We describe 2 unrelated patients presenting with multiple circumferential skin creases, growth retardation, developmental delay, a typical facial appearance and cleft palate. In literature, 6 patients with an almost identical clinical phenotype have been described. This well recognizable syndrome should be distinguished from the "Michelin Tire Baby" syndrome and we therefore propose the term "circumferential skin creases Kunze type".status: publishe

Two-Year Refractive Outcomes After Descemet Membrane Endothelial Keratoplasty

Ophthalmic researc