SSFT: selective software fault tolerance

Cataloged from PDF version of article.As technology advances, the processors are shrunk in size and manufactured using higher density transistors which makes them cheaper, more power efficient and more powerful. While this progress is most beneficial to end-users, these advances make processors more vulnerable to outside radiation causing soft errors which occur mostly in the form of single bit flips on data. For protection against soft errors, hardware techniques like ECC (Error Correcting Code) and Ram Parity Memory are proposed to provide error detection and even error correction capabilities. While hardware techniques provide effective solutions, software only techniques may offer cheaper and more flexible alternatives where additional hardware is not available or cannot be introduced to existing architectures. Software fault detection techniques -while powerful- rely mostly on redundancy which causes significant amount of performance overhead and increase in the number of bits susceptible to soft errors. In most cases, where reliability is a concern, the availability and performance of the system is even a bigger concern, which actually requires a multi objective optimization approach. In applications where a certain margin of error is acceptable and availability is important, the existing software fault tolerance techniques may not be applied directly because of the unacceptable performance overheads they introduce to the system. Our technique Selective Software Fault Tolerance (SSFT) aims at providing availability and reliability simultaneously, by providing only required amount of protection while preserving the quality of the program output. SSFT uses software profiling information to understand application’s vulnerabilities against transient faults. Transient faults are more likely to occur in instructions that have higher execution counts. Additionally, the instructions that cause greater damage in program output when hit by transient faults, should be considered as application weaknesses in terms of reliability. SSFT combines these information to eliminate the instructions from fault tolerance, that are less likely to be hit by transient errors or cause errors in program output. This approach reduces power consumption and redundancy (therefore less data bits susceptible to soft errors), while improving performance and providing acceptable reliability. This technique can easily be adapted to existing software fault tolerance techniques in order to achieve a more suitable form of protection that will satisfy different concerns of the application. Similarly, hybrid and hardware only approaches may also take advantage of the optimizations provided by our technique.Turhan, TuncerM.S

Vancomycin versus Linezolid in the Treatment of Methicillin-Resistant Staphylococcus aureus Meningitis

Abstract Background: Vancomycin is the mainstay of treatment for methicillin-resistant Staphylococcus aureus (MRSA) meningitis. However, successful outcomes with linezolid have not been reported in a large series of patients. We conducted a single-center retrospective cohort study to compare vancomycin with linezolid in the treatment of MRSA meningitis. Methods: We extracted data and outcomes for all adult patients (age > 18 years) with culture-proved MRSA meningitis who received vancomycin or linezolid between January 2006 and June 2011. A definite diagnosis of meningitis was based on the isolation of MRSA in at least one cerebrospinal fluid (CSF) culture and findings in CSF that are typical of the infection. Linezolid was given intravenously (IV) at a dosage of 600 mg q12h and vancomycin IV at 500 mg q6h. Results: A total of 8 patients with MRSA meningitis (5 male, 3 female; age [mean -SD] 61.6 -13.2 years) received vancomycin and 9 patients (7 male, 2 female; age 59.1 -15.6 years) received linezolid. All isolated strains of MRSA were susceptible to both vancomycin and linezolid. The rates of microbiologic success with linezolid or vancomycin, in terms of clearance of MRSA from CSF on day 5, were 7/9 and 2/8 (p = 0.044, Fisher exact test). No severe adverse events occurred in either treatment arm of the study. One-month survival of the patients in whom treatment was successful microbiologically was 2/2 in the vancomycin-treated group and 4/7 in the linezolidtreated group. Minimum inhibitory concentration (MIC) data for vancomycin were available for 5/6 treatment failures with vancomycin, and vancomycin MIC values of these five strains were 2 mg/L. Conclusion: Analysis of the findings in the limited cohorts in our study suggests that linezolid is superior to vancomycin for treating MRSA meningitis, especially in cases in which there is a high MIC (2 mg/L) for vancomycin. A clinical study involving larger cohorts may increase the evidence available in relation to this question

Dry-field maneuver for controlling the massive intraventricular bleeding during neuroendoscopic procedures

WOS: 000424707300026PubMed ID: 29124389Massive hemorrhages pose a significant problem in intraventricular endoscopic surgeries. These hemorrhages have the potential to cause mortality and morbidity, particularly in excisional surgeries. Often, the bleeding can be controlled only by cauterization and liquid irrigation, due to the incongruity of the use of antihemorrhagic agents in the fluid. The final option to stop the massive bleeding is the dry-field maneuver. In this study, the effects and clinical results of the dry-field maneuver in bleeding control of a massive bleeding were investigated. Dry-field maneuver was retrospectively studied in a patient population that had massive bleeding during intraventricular endoscopic procedures. Dry-field maneuver was used in seven patients. Four of these patients underwent some excisional surgery. The other two patients were operated for an endoscopic third ventriculostomy and one for intraventricular hemorrhage evacuation. It was observed that the hemorrhage in patients stopped rapidly after the dry-field maneuver. Moreover, there was no need for an antihemorrhagic material. Dry-field maneuver is an option for providing hemostasis, particularly, for a massive hemorrhage. It also has the potential to be used in elective surgeries because it improves the visual quality

Prof. Dr. Yusuf ERŞAHİN

Dr. Yusuf Erşahin, Professor of Neurosurgery at the Agean University has been passed away at very early and most productive age of his life. He was a worldwide famous Turkish Neurosurgeon and also was a serious contributor and international pioneer surgeon of paediatric spinal surgery.Ege Üniversitesi Beyin ve Sinir Cerrahisi öğretim üyesi Prof. Dr. Yusuf Erşahin erken yaşta, en verimli çağında aramızdan ayrıldı. Türkiye’de nöroşirurjinin dünya çapındaki isimlerinden olan Yusuf Erşahin, aynı zamanda pediatrik spinal cerrahiye uluslararası ve ulusal büyük katkıları olan bir öncü bilim insanı idi

Indirect Bypass Procedures for Moyamoya Disease in Pediatric Patients

WOS: 000290371700007PubMed ID: 21534196AIM: Many direct and indirect surgical intervention methods have been defined for the treatment of moyamoya disease. Indirect surgical procedures have been increasingly used. In this study, indirect surgical intervention methods especially used in combination with pial synangiosis were assessed together with other indirect methods. MATERIAL and METHODS: 11 patients who were treated with an indirect bypass procedures at our clinic and followed for at least three years were retrospectively examined. 19 surgical interventions were performed for 18 patient hemispheres pertaining to these patients. 4 indirect surgical revascularization methods were used for three patient hemispheres. On the other hand, indirect procedures combined with pial synangiosis were applied in 11 operations. In addition, the "multiple burr-hole surgery" method was used in 4 four operations performed for two patients. RESULTS: The clinical success rate was 66.6% for patients where the techniques were applied with pial synangiosis. No new ischemic or hemorrhagic attack was observed during the follow-up period in any of these patients in this series. CONCLUSION: Pial synangiosis is a modification that Increases the success rate of indirect surgical methods. In addition, high success rates have been reported in recent publications related to multiple burr-hole surgery. This method is a candidate choice of surgical intervention for selected patients

Refusal strategies of Turkish pre-service teachers of English: A focus on gender and status of the interlocutor*

In today’s world, the great demand for using English entails language users to be pragmatically competent so that they could adapt themselves to differing requirements of various contexts. Within those contexts, some factors such as the culture of the target language, the speech act used in the interaction, status and gender of the interlocutors are accepted as essential components. Refusals, one of the most difficult speech acts to perform based on their face threatening nature, were chosen as the main concern of the present study. In an attempt to find out what kind of refusal strategies are employed by Turkish pre-service teachers of English, 27 first year students (14 males and 13 females) at Çukurova University were randomly chosen. Data for the study were collected via a Written Discourse Completion Test (WDCT) in which the participants were to respond nine scenarios (three lower, three equal and three higher interlocutors). Data analysis concentrated on two main variables: gender of the participants and the status of the interlocutors. In addition to those, refusal combinations utilized by the participants was another focal point of the study. The whole qualitative data were discussed through descriptive statistics and chi-square analyses, and “excuse, reason, explanation” was found to be the most frequent refusal strategy used by the participants. Another important finding is that males were found to prefer directly uttering “no” more frequently than females. It was also found that the number of the strategy combinations increases as the status of the interlocutor rises. © 2019 JLLS and the Authors - Published by JLLS.SED-2017-9083The researchers appreciate the support provided by Çukurova University Scientific Research Projects Coordination Center (Project no: SED-2017-9083)