Redundancy technique is used to improve performance and achieving to increase the lifetime of a system. Nowadays, the redundancy method is applied in many industries. One of the common methods of redundancy is its utilization in the switching systems. In switching systems, one or more components are considered active mode and the others in the standby state to be used by switch if necessary. In order to be fully utilized all the components in the redundant device, the switch unit must perform its function, such as switching, perfectly. Successful Coverage by switch unit is expressed with a Probability. In this paper, a new approach to the likelihood of switch success is proposed, and showing that as increases switching in the system, the efficiency and performance of the switch gradually decreases. The analysis of this method was based on the stress-strength method. Finally, a few numerical examples for the validation of results were applied.

Since the binomial distribution is discrete‎, ‎finding accurate confidence intervals for its parameters is not easily achievable‎. ‎Many approximate confidence intervals have been suggested for the binomial distribution's ratio parameter thus far‎. ‎As we know‎, ‎these confidence intervals have not been compared based on the maximum Coverage probabilities‎. ‎This article aims to evaluate six widely used confidence intervals for the binomial distribution's ratio parameter‎, ‎focusing on their accurate maximum Coverage probabilities criterion.

Background and Aims: Metal-free and fiber-reinforced composite (FRC) restorations have drawn considerable attention and interest in recent years for restoring in the posterior area due to their improved esthetics. Fracture resistance is one of the most important mechanical properties of materials because of 500-600 N load of occlusion. The restorations should tolerate this load. The purpose of this in vitro study was to compare the fracture resistance of FRC with that of zirconia all-ceramic for posterior partial dentures.Materials and Methods: Forty extracted human intact teeth (20 first premolars and 20 first molars) selected for fabricating 10 pairs of fiber-reinforced composite and 10 pairs of zirconia all-ceramic bridges. After receiving standard tooth preparation, the teeth were mounted with 7.5 mm distance between each other. The bridges were made and cemented on the teeth. Then the restorations were stored in 37oC water for 30 days. The fracture resistance was measured using mechanical testing machine with cross-head speed of 1mm/min. Data were evaluated by Independent sample t test.Results: The mean fracture resistance in the ceramic group was 1329.41 N and for the F.R.C group was 1118.528 N with significant differences between them (P=0.034). The failure modes were mainly cohesive at pontic area for ceramic samples, but adhesive for FRC samples at pontic area.Conclusion: Both systems showed sufficient fracture resistance for using in posterior area.

Background & Aims: Different scoring systems are used in order to assess the functional quality of intensive care units (ICU) and to predict the required costs and facilities of intensive cares. Variety of scoring systems has been explained that each has advantages and disadvantages. In this study Simplified Acute Physiology Score-III (SAPS-III) and Mortality Probability Model-III (MPM-III) were compared. Materials & Methods: The current cross-sectional study was conducted on 240 non-traumatic patients admitted at ICU of Al-Zahra Hospital in 2016-17. Patients' information including demographics, mean of systolic, diastolic and arterial pressure, pulse rate, respiratory rate, temperature, Glasgow Coma Scale(GCS), WBC, hematocrit, bilirubin, creatinine, arterial blood gas, and the presence of underlying diseases was gathered from the records for measurement of MPM-III and SAPS-III scores and then they were compared. Results: This study was conducted on 240 non-traumatic patients. Discrimination of MPM-III in cutoff point of 0. 17 was 0. 83(P<0. 001; 95%CI: 0. 765-0. 898), sensitivity and specificity of this test in prediction of non-traumatic mortality was 82% and 73%, respectively. Discrimination of SAPS-III in cut-off of 48. 5 was 0. 78(P<0. 001; 95%CI: 0. 72-0. 84), while its sensitivity and specificity was 83% and 70%, respectively. Duration of ICU hospitalization (P=0. 028 and 0. 002) and duration of intubation (P=0. 001 and <0. 001) had direct association with mortality based on both scoring systems while total duration of hospitalization was only significant in SAPSIII (P=0. 002). Conclusion: Comparison of SAPS-III and MPM-III in non-traumatic patients presented a higher discrimination ability for MPM-III. In addition, findings showed that mortality in MPM-III was in association with duration of ICU admission and intubation while for SAPS-III, in addition to previous factors, total duration of hospitalization was associated as well.

Background: Intensive care unit (ICU) is among the most important hospital wards. Variety of scoring systems for evaluation of patients' status and prediction of hospitalization outcomes in ICU has been raised that each has strong and weak points; assessment of these characteristics tends to promote new scoring systems. The current study compared scoring systems of Mortality Probability Model-III (MPM-III) and Simplified Acute Physiology Score-III (SAPS-III) in trauma patients in ICU. Methods: This randomized cross-sectional study was conducted on 200 patients admitted in ICU because of trauma in years 2016-17. Patients' information including demographics, mean of systolic, diastolic, and arterial blood pressure, pulse, respiratory rate, temperature, Glasgow coma scale (GCS), arterial gas analysis, white blood cell (WBC) counts, hematocrit, bilirubin, creatinine, type of admission, and presence of underlying diseases were extracted from records; MPM-III and SAPS-III were measured for these patients and compared. Findings: MPM-III scoring system had discrimination of 0. 935 [95% confidence interval (95%CI): 0. 89-0. 97; P < 0. 001) in cut-off point of 0. 13, and its sensitivity and specificity was 87% and 84%, respectively. For SAPS-III system, in cut-off point of 0. 13, the discrimination was 0. 77 (95%CI: 0. 69-0. 85; P < 0. 001), with the sensitivity of 80% and specificity of 68%. Based on both MPM-III and SAPS-III systems, mortality was in correlation with duration of ICU admission (P = 0. 001 for both systems) and duration of intubation (P < 0. 001 for both systems), while only for SAPS-III, total duration of hospitalization was in correlation with mortality (P < 0. 001). Conclusion: MPM-III scoring system was superior to SAPS-III regarding discrimination power in trauma patients. In addition, based on both systems, mortality rate was in direct association with days of ICU admission and intubation duration.