| 1. |
- Arlat, Jean, et al.
(författare)
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MEFISTO: A Series of Prototype Tools for Fault Injection into VHDL Models
- 2003
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Ingår i: Fault Injection Techniques and Tools for Embedded Systems Reliability Evaluation, Kluwer Academic Publishing. - 1402075898 ; , s. 177-193
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The early assessment of the fault tolerance mechanisms is an essential task in the design of dependable computing systems. Simulation languages offer the necessary support to carry out such a task. Due to its wide spectrum of application and hierarchical features, VHDL is a powerful simulation language. This chapter summarizes the main results of a pioneering effort aimed at developing and experimenting supporting tools for fault injection into VHDL models. The chapter first identifies the possible means to inject faults into a VHDL model. Then, we describe two prototype tools that were developed using each of the main injection strategies previously identified. Finally, some general insights and perspectives are briefly discussed.
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| 2. |
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| 3. |
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| 4. |
- Aidemark, Joakim, 1965, et al.
(författare)
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Experimental Dependability Evaluation of the Artk68-FT Real-time Kernel
- 2004
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Ingår i: Proc. of the International Conference on Real-Time and Embedded Computer Systems and Applications. ; , s. 625-645
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Konferensbidrag (refereegranskat)abstract
- This paper presents an experimental dependability evaluation of a small real-time kernel called Artk68-FT intended for distributed fault-tolerant real-time systems. A main goal of this research is to improve the dependabilityof such systems by using a two-level approach for tolerating transient faults. By providing mechanisms in the kernel for tolerating transient faults at the node level, the overall reliability is improved since the recovery time is much shorter at the node level than at the system level. Permanent faults and transient faults that cannot be handled at the node level have to be handled at the system level. The experimental evaluation was performed using fault injection experiments on the MC68340 microcontroller executing the kernel and three application tasks. The experimental results show that no wrong results were produced when faults were injected during execution of a critical task protected by Artk68-FT. Moreover, no application crashes were observed in the fault injection experiments with Artk68-FT compared to experiments with a version of the kernel without fault handling mechanisms.
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| 5. |
- Aidemark, Joakim, 1965, et al.
(författare)
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Experimental evaluation of time-redundant execution for a brake-by-wire application
- 2002
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Ingår i: International Conference on Dependable Systems and Networks, 2002. DSN 2002. Proceedings. - 0769511015 ; , s. 210-215
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Konferensbidrag (refereegranskat)abstract
- This paper presents an experimental evaluation of a brake-by-wire application that tolerates transient faults by temporal error masking. A specially designed real-time kernel that masks errors by triple time-redundant execution and voting executes the application on a fail-stop computer node. The objective is to reduce the number of node failures by masking errors at the computer node level. The real-time kernel always executes the application twice to detect errors, and ensures that a fail-stop failure occurs if there is not enough CPU-time available for a third execution and voting. Fault injection experiments show that temporal error masking reduced the number of fail-stop failures by 42% compared to executing the brake-by-wire task without time redundancy.
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| 6. |
- Aidemark, Joakim, 1965, et al.
(författare)
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On the probability of detecting data errors generated by permanent faults using time redundancy
- 2003
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Ingår i: Proceedings of the 9th IEEE International On-Line Testing Symposium, Kos, 7-9 July 2003. - 0769519687 ; , s. 68-74
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Konferensbidrag (refereegranskat)abstract
- Time redundant execution of tasks and comparison of results is a well-known technique for detecting transient faults in computer systems. However, time redundancy is also capable of detecting permanent faults that occur during or between the executions of two task replicas, provided the faults affect the results of the two tasks in different ways. In this paper, we derive an expression for estimating the probability of detecting data errors generated by permanent faults with time redundant execution. The expression is validated experimentally by injecting permanent stuck-at faults into a multiplier unit of a microprocessor. We use the derived expression to show how tasks can be scheduled to improve the detection probability of errors generated by permanent faults. We also show that the detection capability of permanent faults is low for the Temporal Error Masking (TEM) technique (i.e. triplicated execution and voting to mask transient faults) and may not be increased by scheduling. Thus, we propose complementing TEM with special test tasks.
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| 7. |
- Aidemark, Joakim, 1965, et al.
(författare)
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Path-Based Error Coverage Prediction
- 2002
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Ingår i: Journal of Electronic Testing: Theory and Applications (JETTA). - 1573-0727 .- 0923-8174. ; 18:3, s. 343-349
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Tidskriftsartikel (refereegranskat)abstract
- We present an analytical technique that uses fault injection data for estimating the coverage of concurrent error detection mechanisms in microprocessors. A major problem in such estimations is that the coverage depends on the program executed by the microprocessor as well as the input sequence to the program. We propose a method that predicts the error coverage for a specified input sequence based on fault injection data obtained for another input sequence. Our results show that post-injection analysis is a promising approach for reducing the cost of coverage estimation.
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| 8. |
- Azhar, Najia, et al.
(författare)
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Laparoscopic Lavage vs Primary Resection for Acute Perforated Diverticulitis: Long-term Outcomes From the Scandinavian Diverticulitis (SCANDIV) Randomized Clinical Trial
- 2021
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Ingår i: JAMA Surgery. - Chicago, IL, United States : American Medical Association. - 2168-6254 .- 2168-6262. ; 156:2, s. 121-127
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Perforated colonic diverticulitis usually requires surgical resection, with significant morbidity. Short-term results from randomized clinical trials have indicated that laparoscopic lavage is a feasible alternative to resection. However, it appears that no long-term results are available.OBJECTIVE To compare long-term (5-year) outcomes of laparoscopic peritoneal lavage and primary resection as treatments of perforated purulent diverticulitis.DESIGN, SETTING, AND PARTICIPANTS This international multicenter randomized clinical trial was conducted in 21 hospitals in Sweden and Norway, which enrolled patients between February 2010 and June 2014. Long-term follow-upwas conducted between March 2018 and November 2019. Patients with symptoms of left-sided acute perforated diverticulitis, indicating urgent surgical need and computed tomography-verified free air, were eligible. Those available for trial intervention (Hinchey stagesINTERVENTIONS Patients were assigned to undergo laparoscopic peritoneal lavage or colon resection based on computer-generated, center-stratified block randomization.MAIN OUTCOMES AND MEASURES The primary outcome was severe complications within 5 years. Secondary outcomes included mortality, secondary operations, recurrences, stomas, functional outcomes, and quality of life.RESULTS Of 199 randomized patients, 101were assigned to undergo laparoscopic peritoneal lavage and 98were assigned to colon resection. At the time of surgery, perforated purulent diverticulitiswas confirmed in 145 patients randomized to lavage (n = 74) and resection (n = 71). The median follow-upwas 59 (interquartile range, 51-78; full range, 0-110) months, and 3 patientswere lost to follow-up, leaving a final analysis of 73 patients who had had laparoscopic lavage (mean [SD] age, 66.4 [13] years; 39 men [53%]) and 69 who had received a resection (mean [SD] age, 63.5 [14] years; 36 men [52%]). Severe complications occurred in 36%(n = 26) in the laparoscopic lavage group and 35%(n = 24) in the resection group (P = .92). Overall mortalitywas 32%(n = 23) in the laparoscopic lavage group and 25%(n = 17) in the resection group (P = .36). The stoma prevalencewas 8%(n = 4) in the laparoscopic lavage group vs 33% (n = 17; P =.002) in the resection group among patients who remained alive, and secondary operations, including stoma reversal, were performed in 36%(n = 26) vs 35%(n = 24; P = .92), respectively. Recurrence of diverticulitiswas higher following laparoscopic lavage (21% [n = 15] vs 4%[n = 3]; P = .004). In the laparoscopic lavage group, 30%(n = 21) underwent a sigmoid resection. Therewere no significant differences in the EuroQoL-5Dquestionnaire or Cleveland Global Quality of Life scores between the groups.CONCLUSIONS AND RELEVANCE Long-term follow-up showed no differences in severe complications. Recurrence of diverticulitis after laparoscopic lavage was more common, often leading to sigmoid resection. This must be weighed against the lower stoma prevalence in this group. Shared decision-making considering both short-term and long-term consequences is encouraged.
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| 9. |
- Collin, Åsa
(författare)
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Colorectal cancer : Aspects of staging, treatment, recurrence and survival
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Colorectal cancer is the third most common malignancy in the world, and major breakthroughs have been made regarding both surgical and oncological treatment. Still, postoperative complications, such as perineal infections after abdominoperineal resection (APR), are a major cause of morbidity, and distant recurrence rate is nearly 20%. In this thesis, means to improve postoperative infection rates, nodal staging in rectal cancer (and resulting overtreatment through (chemo)radiotherapy), cancer recurrence rates and survival, were investigated. In Paper I, the effects on complication rates, recurrence rates and survival of antibiotics applied locally after an APR, by means of a gentamicin-collagen sponge in the perineal wound, were analysed in a randomized setting. No difference was seen regarding any of the endpoints. The results suggest that local antibiotics can safely be omitted in APRs. Paper II investigated the effects of mechanical bowel preparation (MBP) on cancer recurrence and survival, among colon cancer patients undergoing a colon resection. Data from the Swedish randomized MBP trial were used. After follow-up, no improvement in recurrence rates or overall survival was seen, but cancer-specific survival was improved in the MBP group. In conclusion, MBP might be a prognostic favourable factor for outcome in colon cancer patients. In Paper III, the effect of new national guideline criteria for MRI nodal staging in rectal cancer was assessed, regarding the proportion of clinically positive nodes and staging accuracy, and resulting effects on preoperative (chemo)radiotherapy use. Comparing the two years prior to guideline implementation with the two years after implementation revealed a significant decrease in the proportion clinically positive nodes, but staging accuracy remained low, and (chemo)radiotherapy rates decreased with seemingly no correlation to guidelines. Thus, new guidelines decreased the rate of clinically positive nodes, but nodal accuracy remained poor and nodal staging should perhaps not be a criterion in preoperative treatment decisions. Paper IV investigated the impact of the total mesorectal excision quality, by means of the three Quirke grades, mesorectal (best quality), intramesorectal and muscularis propria (worst quality), on recurrence and survival, and assessed risk factors for intramesorectal or muscularis propria resection. Muscularis propria grade was associated with a higher local recurrence rate, but not with distant recurrence or survival. Several factors were associated with intramesorectal and muscularis propria grade, and more caution is warranted in these patients. In conclusion, this thesis provides insight into treatment choice, and the association of day-to-day treatment details with postoperative complications, recurrence and survival rates, as well as the challenges of nodal staging.
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| 10. |
- Collin, Åsa, et al.
(författare)
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Impact of mechanical bowel preparation on survival after colonic cancer resection
- 2014
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Ingår i: British Journal of Surgery. - : Wiley: 12 months. - 0007-1323 .- 1365-2168. ; 101:12, s. 1594-
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Tidskriftsartikel (refereegranskat)abstract
- Background: A randomized study in 1999-2005 of mechanical bowel preparation (MBP) preceding colonic resection found no decrease in postoperative complications. The aim of the present study was to evaluate the long-term effect of MBP regarding cancer recurrence and survival after colonic resections. Methods: The cohort of patients with colonic cancer in the MBP study was followed up for 10 years. Data were collected from registers run by the National Board of Health and Welfare. Register data were validated against information in patient charts. Cox proportional hazards model was used for multivariable analysis of factors predictive of cancer-specific survival. Results: Register analysis showed significantly fewer recurrences, and better cancer-specific and overall survival in the MBP group. After validation, 839 of 1343 patients remained for analysis (448 MBP, 391 no MBP). Eighty (17.9 per cent) of 448 patients in the MBP group and 88 (22.5 per cent) of 391 in the no-MBP group developed a cancer recurrence (P = 0.093). The 10-year cancer-specific survival rate was 84.1 per cent in the MBP group and 78.0 per cent in the no-MBP group (P = 0.019). Overall survival rates were 58.8 and 56.0 per cent respectively (P = 0.186). Conclusion: Patients receiving MBP before elective colonic cancer surgery had significantly better cancer-specific survival after 10 years.
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