| 1. |
- Marto, João Pedro, et al.
(författare)
-
Safety and Outcome of Revascularization Treatment in Patients With Acute Ischemic Stroke and COVID-19: The Global COVID-19 Stroke Registry.
- 2023
-
Ingår i: Neurology. - 1526-632X. ; 100:7
-
Tidskriftsartikel (refereegranskat)abstract
- COVID-19-related inflammation, endothelial dysfunction, and coagulopathy may increase the bleeding risk and lower the efficacy of revascularization treatments in patients with acute ischemic stroke (AIS). We aimed to evaluate the safety and outcomes of revascularization treatments in patients with AIS and COVID-19.This was a retrospective multicenter cohort study of consecutive patients with AIS receiving intravenous thrombolysis (IVT) and/or endovascular treatment (EVT) between March 2020 and June 2021 tested for severe acute respiratory syndrome coronavirus 2 infection. With a doubly robust model combining propensity score weighting and multivariate regression, we studied the association of COVID-19 with intracranial bleeding complications and clinical outcomes. Subgroup analyses were performed according to treatment groups (IVT-only and EVT).Of a total of 15,128 included patients from 105 centers, 853 (5.6%) were diagnosed with COVID-19; of those, 5,848 (38.7%) patients received IVT-only and 9,280 (61.3%) EVT (with or without IVT). Patients with COVID-19 had a higher rate of symptomatic intracerebral hemorrhage (SICH) (adjusted OR 1.53; 95% CI 1.16-2.01), symptomatic subarachnoid hemorrhage (SSAH) (OR 1.80; 95% CI 1.20-2.69), SICH and/or SSAH combined (OR 1.56; 95% CI 1.23-1.99), 24-hour mortality (OR 2.47; 95% CI 1.58-3.86), and 3-month mortality (OR 1.88; 95% CI 1.52-2.33). Patients with COVID-19 also had an unfavorable shift in the distribution of the modified Rankin score at 3 months (OR 1.42; 95% CI 1.26-1.60).Patients with AIS and COVID-19 showed higher rates of intracranial bleeding complications and worse clinical outcomes after revascularization treatments than contemporaneous non-COVID-19 patients receiving treatment. Current available data do not allow direct conclusions to be drawn on the effectiveness of revascularization treatments in patients with COVID-19 or to establish different treatment recommendations in this subgroup of patients with ischemic stroke. Our findings can be taken into consideration for treatment decisions, patient monitoring, and establishing prognosis.The study was registered under ClinicalTrials.gov identifier NCT04895462.
|
|
| 2. |
- Nguyen, Thanh N, et al.
(författare)
-
Global Impact of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events: A 1-Year Follow-up.
- 2023
-
Ingår i: Neurology. - 1526-632X. ; 100:4
-
Tidskriftsartikel (refereegranskat)abstract
- Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020).We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, IVT treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.There were 148,895 stroke admissions in the 1 year immediately before compared with 138,453 admissions during the 1-year pandemic, representing a 7% decline (95% CI [95% CI 7.1-6.9]; p < 0.0001). ICH volumes declined from 29,585 to 28,156 (4.8% [5.1-4.6]; p < 0.0001) and IVT volume from 24,584 to 23,077 (6.1% [6.4-5.8]; p < 0.0001). Larger declines were observed at high-volume compared with low-volume centers (all p < 0.0001). There was no significant change in mechanical thrombectomy volumes (0.7% [0.6-0.9]; p = 0.49). Stroke was diagnosed in 1.3% [1.31-1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82-2.97], 5,656/195,539) of all stroke hospitalizations.There was a global decline and shift to lower-volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared with the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year.This study is registered under NCT04934020.
|
|
| 3. |
- Lindgren, Per, et al.
(författare)
-
A Formal Perspective on IEC 61499 Execution Control Chart Semantics
- 2015
-
Ingår i: 2015 IEEE Trustcom/BigDataSE/ISPA. - Piscataway, NJ : IEEE Communications Society. - 9781467379519 ; , s. 293-300
-
Konferensbidrag (refereegranskat)abstract
- The IEC 61499 standard proposes an event driven execution model for distributed control applications for which an informal execution semantics is provided. Consequently, run-time implementations are not rigorously described and therefore their behavior relies on the interpretation made by the tool provider. In this paper, as a step towards a formal semantics, we focus on the Execution Control Chart semantics, which is fundamental to the dynamic behavior of Basic Function Block elements. In particular we develop a well-formedness criterion that ensures a finite number of Execution Control Chart transitions for each triggering event. We also describe the first step towards the mechanization of the well-formedness checking algorithm in the Coq proof-assistant so that, ultimately, we are able to show, once andforall,thatthisalgorithmiseffectivelycorrectwithrespectto our proposed execution semantics. The algorithm is extractable from the mechanization in a correct-by-construction way, and can be directly incorporated in certified toolchain for analysis, compilation and execution of IEC 61499 models. As a proof of concept a prototype tool RTFM-4FUN has been developed. It performs well-formedness checks on Basic Function Blocks using the extracted algorithm’s code.
|
|
| 4. |
- Lindgren, Per, et al.
(författare)
-
A Real-Time Semantics for the IEC 61499 standard
- 2015
-
Ingår i: Proceedings of 2015 IEEE 20th International Conference on Emerging Technologies & Factory Automation (ETFA 2015). - Piscataway, NJ : IEEE Communications Society. - 9781467379298
-
Konferensbidrag (refereegranskat)abstract
- The IEC 61499 standard provides an executable model for distributed control systems in terms of interacting function blocks. However, the current IEC 61499 standard lacks appropriate timing semantics for the specification of timing requirements, reasoning on timing properties at the model level, and for the timing verification of a specific deployment. In this paper we address this fundamental shortcoming by proposing Real-Time-4-FUN, a real-time semantics for IEC 61499. The key property is the preservation of non-determinism, allowing us to reason on (and verify) timing properties at the model level without assuming any specific scheduling policy or stipulating specific order of execution for the deployment. This provides for a clear separation of concerns, where the designer can focus on properties of the application prior to, and separately from, deployment verification. The proposed timing semantics is backwards compatible to the current standard, thus allow for reuse of existing designs. The transitional property allows timing requirements to propagate to downstream sub-systems, and can be utilized for scheduling both at device and network level. Based on a translation to RTFM-tasks and resources, IEC 61499 the models can be analyzed, compiled and executed. As a proof of concept the timing semantics has been experimentally implemented in the RTFM-core language and the accompanying (thread based) RTFM-RT run-time system.
|
|
| 5. |
- Lindgren, Per, et al.
(författare)
-
Abstract Timers and their Implementation onto the ARM Cortex-M family of MCUs
- 2016
-
Ingår i: SIGBED Review. - : Association for Computing Machinery (ACM). - 1551-3688. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Real-Time For the Masses (RTFM) is a set of languages andtools being developed to facilitate embedded software developmentand provide highly ecient implementations gearedto static verication. The RTFM-kernel is an architecturedesigned to provide highly ecient and predicable Stack ResourcePolicy based scheduling, targeting bare metal (singlecore)platforms.We contribute by introducing a platform independent timerabstraction that relies on existing RTFM-kernel primitives.We develop two alternative implementations for the ARMCortex-M family of MCUs: a generic implementation, usingthe ARM dened SysTick/DWT hardware; and a targetspecic implementation, using the match compare/free runningtimers. While sacricing generality, the latter is moreexible and may reduce overall overhead. Invariants for correctnessare presented, and methods to static and run-timeverication are discussed. Overhead is bound and characterized.In both cases the critical section from release timeto dispatch is less than 2us on a 100MHz MCU. Queue andtimer mechanisms are directly implemented in the RTFMcorelanguage (-core in the following) and can be includedin system-wide scheduling analysis.
|
|
| 6. |
- Lindgren, Per, et al.
(författare)
-
Contract Based Verification of IEC 61499
- 2017
-
Ingår i: IEEE International Conference on Industrial Informatics (INDIN). - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781509028702 ; , s. 132-141
-
Konferensbidrag (refereegranskat)abstract
- The IEC 61499 standard proposes an event drivenexecution model for component based (in terms of FunctionBlocks), distributed industrial automation applications. However,the standard provides only an informal execution semantics, thusin consequence behavior and correctness relies on the designdecisions made by the tool vendor. In this paper we presentthe formalization of a subset of the IEC 61499 standard inorder to provide an underpinning for the static verification ofFunction Block models by means of deductive reasoning. Specifically,we contribute by addressing verification at the component,algorithm, and ECC levels. From Function Block descriptions, enrichedwith formal contracts, we show that correctness of componentcompositions, as well as functional and transitional behaviorcan be ensured. Feasibility of the approach is demonstrated bymanually encoding a set of representative use-cases in WhyML,for which the verification conditions are automatically derived(through the Why3 platform) and discharged (using automaticSMT-based solvers). Furthermore, we discuss opportunities andchallenges towards deriving certified executables for IEC 61499models.
|
|
| 7. |
- Lindgren, Per, et al.
(författare)
-
End-to-End Response Time of 61499 Distributed Applications over Switched Ethernet
- 2017
-
Ingår i: IEEE Transactions on Industrial Informatics. - : IEEE. - 1551-3203 .- 1941-0050. ; 13:1, s. 287-297
-
Tidskriftsartikel (refereegranskat)abstract
- The IEC 61499 standard provides means to specify distributed control systems in terms of function blocks. For the deployment, each device may hold one or many logical resources, each consisting of a function block network with service interface blocks at the edges. The execution model is event driven (asynchronous), where triggering events may be associated with data (and seen as messages). In this paper, we propose a low complexity implementation technique allowing to assess end-to-end response times of event chains spanning over a set of networked devices. Based on a translation of IEC 61499 to RTFM1-tasks and resources, the response time for each task in the system at device-level can be derived using established scheduling techniques. In this paper, we develop a holistic method to provide safe end-to-end response times taking both intra- and inter-device delivery delays into account. The novelty of our approach is the accuracy of the system scheduling overhead characterization. While the device-level (RTFM) scheduling overhead was discussed in previous works, the network-level scheduling overhead for switched Ethernets is discussed in this paper. The approach is generally applicable to a wide range of COTS Ethernet switches without a need for expensive custom solutions to provide hard real-time performance. A behavior characterization of the utilized switch determines the guaranteed response times. As a use case, we study the implementation onto (single-core) ARMcortex based devices communicating over a switched Ethernet network. For the analysis, we define a generic switch model and an experimental setup allowing us to study the impact of network topology as well as 802.1Q quality of service in a mixed critical setting. Our results indicate that safe sub millisecond end-to-end response times can be obtained using the proposed approach.
|
|
| 8. |
- Lindgren, Per, et al.
(författare)
-
Response Time for IEC 61499 over Ethernet
- 2015
-
Ingår i: IEEE International Conference on Industrial Informatics. - Piscataway, NJ : IEEE Communications Society. - 9781479966493 ; , s. 1206-1212
-
Konferensbidrag (refereegranskat)abstract
- The IEC 61499 standard provides means to specify distributed control systems in terms of function blocks. For the deployment, each device may hold one or many logical resources, each consisting of a function block network with service interface blocks at the edges. The execution model is event driven (asynchronous), where triggering events may be associated with data (and seen as a message). In this paper we propose a low complexity implementation technique allowing to asses end-to-end response time of event chains spanning a networked devices. Based on a translation of IEC 61499 to RTFM-tasks and resources, the response time for each task in the system can be derived using established scheduling techniques. In this paper we develop a method to provide safe end-to-end response time taking both intra- and inter-device delivery delays into account. As a use case we study the implementation onto (single-core) ARMcortex based devices communicating over a switched Ethernet network. For the analysis we define a generic switch model, and an experimental setup allowing us to study the impact of network topology as well as 802.1Q quality of service in a mixed critical setting. Our results indicate that safe sub milli-second end-to-end response times can be obtained using the proposed approach.
|
|
| 9. |
- Lindgren, Per, et al.
(författare)
-
RTFM-core : Language and Implementation
- 2014
-
Konferensbidrag (refereegranskat)abstract
- Robustness, real-time properties and resource eciency arekey properties to embedded devices of the CPS/IoT era. Inthis paper we propose a language approach RTFM-core,and show its potential to facilitate the development processand provide highly ecient implementations amendablefor static verication. Our programming model is reactive,based on the familiar notions of concurrent tasksand (single-unit) resources. The language is kept minimalistic,capturing the static task, communication and resourcestructure of the system. Whereas C-source can be arbitrarilyembedded in the model, and/or externally referenced,the instep to mainstream development is minimal, and asmooth transition of legacy code is possible. A prototypecompiler implementation for RTFM-core is presented. Thecompiler generates C-code output that compiled togetherwith the RTFM-kernel primitives runs on bare metal. TheRTFM-kernel guarantees deadlock-lock free execution andeciently exploits the underlying interrupt hardware forstatic priority scheduling and resource management underthe Stack Resource Policy. This allows a plethora of wellknownmethods to static verication (response time analysis,stack memory analysis, etc.) to be readily applied. The proposedlanguage and supporting tool-chain is demonstratedby showing the complete process from RTFM-core sourcecode into bare metal executables for a light-weight ARMCortexM3 target.
|
|
| 10. |
- Lindgren, Per, et al.
(författare)
-
RTFM-core : Language and Implementation
- 2015
-
Ingår i: 2015 IEEE 10th Conference on Industrial Electronics and Applications (ICIEA). - Piscataway, NJ : IEEE Communications Society. - 9781479983896 ; , s. 990-995
-
Konferensbidrag (refereegranskat)abstract
- Robustness, real-time properties and resource efficiency are key properties to embedded devices of the CPS/IoT era. In this paper we propose a language approach RTFMcore, and show its potential to facilitate the development process and provide highly efficient and statically verifiable implementations. Our programming model is reactive, based on the familiar notions of concurrent tasks and (single-unit) resources. The language is kept minimalistic, capturing the static task, communication and resource structure of the system. Whereas C-source can be arbitrarily embedded in the model, and/or externally referenced, the instep to mainstream development is minimal, and a smooth transition of legacy code is possible. A prototype compiler implementation for RTFM-core is presented. The compiler generates C-code output that compiled together withtheRTFM-kernelprimitivesrunsonbaremetal.TheRTFMkernel guarantees deadlock-lock free execution and efficiently exploits the underlying interrupt hardware for static priority scheduling and resource management under the Stack Resource Policy. This allows a plethora of well-known methods to static verification (response time analysis, stack memory analysis, etc.) to be readily applied. The proposed language and supporting tool-chain is demonstrated by showing the complete process from RTFM-core source code into bare metal executables for a lightweight ARM-Cortex M3 target.
|
|
