Implementing Multi-Periodic Critical Systems: from Design to Code Generation

This article presents a complete scheme for the development of Critical Embedded Systems with Multiple Real-Time Constraints. The system is programmed with a language that extends the synchronous approach with high-level real-time primitives. It enables to assemble in a modular and hierarchical manner several locally mono-periodic synchronous systems into a globally multi-periodic synchronous system. It also allows to specify flow latency constraints. A program is translated into a set of real-time tasks. The generated code (\C\ code) can be executed on a simple real-time platform with a dynamic-priority scheduler (EDF). The compilation process (each algorithm of the process, not the compiler itself) is formally proved correct, meaning that the generated code respects the real-time semantics of the original program (respect of periods, deadlines, release dates and precedences) as well as its functional semantics (respect of variable consumption).Comment: 15 pages, published in Workshop on Formal Methods for Aerospace (FMA'09), part of Formal Methods Week 2009

Physical activity, hormone replacement therapy and breast cancer risk : a meta-analysis of prospective studies

Lower risk of breast cancer has been reported among physically active women, but the risk in women using hormone replacement therapy (HRT) appears to be higher. We quantified the association between physical activity and breast cancer, and we examined the influence that HRT use and other risk factors had on this association. After a systematic literature search, prospective studies were meta-analysed using random-effect models applied on highest versus lowest level of physical activity. Dose-response analyses were conducted with studies reporting physical activity either in hours per week or in hours of metabolic equivalent per week (MET-h/week). The literature search identified 38 independent prospective studies published between 1987 and 2014 that included 116,304 breast cancer cases. Compared to the lowest level of physical activity, the highest level was associated with a summary relative risk (SRR) of 0.88 (95% confidence interval [CI] 0.85, 0.90) for all breast cancer, 0.89 (95% CI 0.83, 0.95) for ER+/PR+ breast cancer and 0.80 (95% CI 0.69, 0.92) for ER-/PR- breast cancer. Risk reductions were not influenced by the type of physical activity (occupational or non-occupational), adiposity, and menopausal status. Risk reductions increased with increasing amounts of physical activity without threshold effect. In six studies, the SRR was 0.78 (95% CI 0.70, 0.87) in women who never used HRT and 0.97 (95% CI 0.88, 1.07) in women who ever used HRT, without heterogeneity in results. Findings indicate that a physically inactive women engaging in at least 150 min per week of vigorous physical activity would reduce their lifetime risk of breast cancer by 9%, a reduction that might be two times greater in women who never used HRT. Increasing physical activity is associated with meaningful reductions in the risk of breast cancer, but in women who ever used HRT, the preventative effect of physical activity seems to be cancelled out

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We thank Raimondi et al. for their alternative interpretation of our results on the prognostic value of 25-hydroxyvitamin D3 (25[OH]D3) serum level in melanoma patients. With the observation that standardized value of 25(OH)D3 at diagnosis was not a prognostic factor, our major finding was that a change of 25(OH)D3 serum level upon time in both directions was associated with worse disease-free and overall survivals, with U-shaped curves. We postulated that this latter result was unlikely to be a direct consequence of vitamin D biological actions but rather reflected a global instability in patients’ metabolisms, which finally impact 25(OH)D3 serum level by any

Melanoma mortality following skin cancer screening in Germany

In 2003, a skin cancer screening campaign based on total body skin examination was launched in the federal state of Schleswig-Holstein, Germany. 20% of adults aged 20 and over were screened. In 2008, a 48% decline in melanoma mortality was reported. In the same year, skin screening was extended to the rest of Germany. We evaluated whether melanoma mortality trends decreased in Germany as compared with surrounding countries where skin screening is uncommon. We also evaluated whether the initial decreasing mortality trend observed in Schleswig-Holstein was maintained with a longer follow-up.  Regional and national melanoma mortality data from 1995 to 2013 were extracted from the GEKID database and the Federal Statistical Office. Mortality data for Germany and surrounding countries from 1980 to 2012 were extracted from the WHO mortality database.  Age-adjusted (European Standard Population) mortality rates were computed and joinpoint analysis performed for Schleswig-Holstein, Germany and surrounding countries.  In Schleswig-Holstein, melanoma mortality rates declined by 48% from 2003 to 2008, and from 2009 to 2013 returned to levels observed before screening initiation. During the 5 years of the national programme (2008-2012), melanoma mortality rates increased by 2.6% (95% CI -0.1 to 5.2) in men and 0.02% (95% CI -1.8 to 1.8) in women. No inflexion point in trends was identified after 2008 that could have suggested a decreasing melanoma mortality. Trends of cutaneous melanoma mortality in Germany from 1980 to 2012 did not differ from those observed in surrounding countries.  The transient decrease mortality in Schleswig-Holstein followed by return to pre-screening levels could reflect a temporal modification in the reporting of death causes. An in-depth evaluation of the screening programme is required

Study on potato consumption will increase confusion regarding food and the risk of gestational diabetes

Using data from the Nurses’ Health Study II, Bao and colleagues found a higher prevalence of gestational diabetes mellitus (GDM) with increasing potato consumption.1 The authors stated that the high glycaemic index of potatoes, which causes a sharp postprandial rise in blood glucose concentrations and a risk of associated pancreatic β cells exhaustion, could explain this association

Stable incidence of advanced breast cancer argues against screening effectiveness

Swedish trials on mammography screening of women aged 40-74 years indicated that two to four rounds of screening could significantly reduce the risk of being diagnosed with and dying from advanced breast cancer.1 Because stage at diagnosis is independent of treatment efficacy, the trials concluded that the introduction of screening in general populations would be reflected by a reduced incidence of advanced breast cancer and mortality from breast cancer

Experiences in using model checking to verify real time properties of a landing gear control system

International audienceThis paper presents experiences in using several model checking tools to verify properties of a critical real time embedded system. The tools we tested are Lesar, SMV, Prover Plug In for SCADE and Uppaal. The application is the landing gear control system of a military aircraft, developed by Dassault Aviation. The property to be verified states that the gear must be down in at most 14 seconds. Results (success and verification time) depend a lot on the way time is handled by the verification tools

TPAP An algebra of preemptive processes for verifying real-time systems with shared resources

AbstractThis paper describes a timed process algebra called TPAP. The aim of this algebra is to allow the modelisation of real time embedded processes sharing common resources, and which are sensitive to communication delays and scheduling strategies. Timed broadcasting and process preemption by interruption events are the two main fundamental notions of the algebra. They allow description of schedulers and asynchronous communication mediums, thus which can be taken into account when verifying the real time behaviour of the global system. We first present the process algebra and discuss its properties. A case study from the avionics area is then developed using TPAP, and formally verified by translation into the UPPAAL model checker

The forthcoming inexorable decline of cutaneous melanoma mortality in light-skinned populations

Reasons underlying time changes in cutaneous melanoma mortality in light-skinned populations are not well understood. An analysis of long-term time trends in melanoma mortality was carried out after regrouping countries in homogeneous regions.  Using the World Health Organisation (WHO) mortality database, age-period-cohort models were fitted for seven regions where the majority of population is light-skinned. Cohort effects are denoted as changes in rates occurring at different times in steadily older age groups. Period effects are denoted as changes in rates occurring simultaneously in several age groups.  Cohort effects better explained changes in melanoma mortality over time than period effects. Lifetime risk to die from melanoma increased in successive generations from 1875 until a peak year. Peak years were for subjects born in 1936-1940 in Oceania, 1937-1943 in North America, 1941-1942 in Northern Europe, 1945-1953 in the United Kingdom (UK) and Ireland, 1948 in Western Europe and 1957 in Central Europe. After peak years, lifetime risk of melanoma death gradually decreased in successive generations and risks of subjects born in 1990-1995 were back to risk levels observed for subjects born before 1900-1905. In Southern Europe, birth years with highest lifetime risk of melanoma death have not yet been attained. As time passes, melanoma deaths will steadily rarefy in younger age groups and concentrate in older age groups, for ultimately fade away after 2040-2050.  Independently from screening or treatment, over next decades, death from melanoma is likely to become an increasingly rare event. The temporary epidemic of fatal melanoma was most probably due to excessive UV-exposure of children that prevailed in 1900-1960, and mortality decreases would be due to progressive reductions in UV-exposure of children over the last decades

End-to-end latency and temporal consistency analysis in networked real-time systems

International audienceCritical embedded systems are often designed as a set of real-time tasks, running on shared computing modules, and communicating through networks. Because of their critical nature, such systems have to meet strict timing properties. To help the designers to prove the correctness of their system, the real-time systems community has developed numerous approaches for analysing the worst case scenarios either on the processors (e.g., worst case response time of a task) or on the networks (e.g., worst case traversal time of a message). These approaches provide results only for local components behaviours. However, there is a growing need for having a global view of the system, in order to determine end-to-end properties. Such a property applies to functional chains which describe the behaviour of sequences of tasks. We propose an approach to analyse worst case behaviour along functional chains in critical embedded systems. It is based on mixed integer linear programming (MILP) and is general in the sense that it can be applied to a variety of end-to-end properties. This paper focuses on two essential properties: end-to-end latency and temporal consistency. This work was supported by the French National Research Agency within the SATRIMMAP project