Aging effect and test-retest reliability of the sinusoidal harmonic acceleration test and velocity step test using nanotorque rotatory chair

Introduction:Rotatory chair testing has been used to evaluate horizontal canal function.Frequently used tests include sinusoidal harmonic acceleration test(SHAT)and velocity step test(VST).Objectives:Assessment of age effect on the SHAT and VST and assessment of test-retest reliability of the parameters of those two tests.Methods:A prospective study was performed on 100 subjects with no ear or vestibular complaints and normal vestibular evaluation.They were divided into two groups;Group A:below 50 years of age and Group B:50 years of age or above.SHAT was presented at frequencies 0.02,0.04,0.08,0.16,0.32,0.64 Hz with a peak velocity of 60°/s.VST was performed using a maximum velocity of 100°/s with acceleration and deceleration of 200°/s2.Thirty subjects were tested twice to assess reliability.Results:Study participants ranged in age from 20 to 67 years.Regarding group A,the mean age was30.92±7.31 and 55.36±4.61 for group B.No significant differences were found in SHAT parameters between the two groups.As well,there was no significant difference in VST per-rotatory time constant,however,post-rotatory time constant was significantly longer for Group B(P value<0.05).Intraclass correlation coefficient(ICC)values showed moderate to good reliability(ICC 0.5800.818)for SHAT parameters for the lower frequencies and indicated moderate reliability for VST time constant(ICC 0.5090.652).Conclusions:Age has no significant effect on the parameters of SHAT and VST.Test-retest reliability is generally good for both tests.

Parameter Estimation Based on Censored Data under Partially Accelerated Life Testing for Hybrid Systems due to Unknown Failure Causes

In general,simple subsystems like series or parallel are integrated to produce a complex hybrid system.The reliability of a system is determined by the reliability of its constituent components.It is often extremely difficult or impossible to get specific information about the component that caused the system to fail.Unknown failure causes are instances in which the actual cause of systemfailure is unknown.On the other side,thanks to current advanced technology based on computers,automation,and simulation,products have become incredibly dependable and trustworthy,and as a result,obtaining failure data for testing such exceptionally reliable items have become a very costly and time-consuming procedure.Therefore,because of its capacity to produce rapid and adequate failure data in a short period of time,accelerated life testing(ALT)is the most utilized approach in the field of product reliability and life testing.Based on progressively hybrid censored(PrHC)data froma three-component parallel series hybrid system that failed to owe to unknown causes,this paper investigates a challenging problem of parameter estimation and reliability assessment under a step stress partially accelerated life-test(SSPALT).Failures of components are considered to follow a power linear hazard rate(PLHR),which can be used when the failure rate displays linear,decreasing,increasing or bathtub failure patterns.The Tempered random variable(TRV)model is considered to reflect the effect of the high stress level used to induce early failure data.The maximum likelihood estimation(MLE)approach is used to estimate the parameters of the PLHR distribution and the acceleration factor.A variance covariance matrix(VCM)is then obtained to construct the approximate confidence intervals(ACIs).In addition,studentized bootstrap confidence intervals(ST-B CIs)are also constructed and compared with ACIs in terms of their respective interval lengths(ILs).Moreover,a simulation study is conducted to demonstrate the performance of the estimation procedures and the methodology discussed in this paper.Finally,real failure data from the air conditioning systems of an airplane is used to illustrate further the performance of the suggested estimation technique.

Performance of Comparative Cervical Tuberculin Test and Serological Methods with Culturing of Nasal Swab in Diagnosis of Bovine Tuberculosis in Cross Breed Cattle Baghdad Iraq: A Comparative Evaluation

This study was designed to assess the diagnostic value of Rapid Antigen bovine TB antibody test kit (RAT) and any association with cervical comparative tuberculin test (CCTT), (iELISA) and nasal swabs culturing, among based detection of M. bovis infection. A herd of 21 animals aged 1 - 8 years cross bread cattle of college of veterinary medicine. 19 (90.47%) animals had good body condition scores, two bulls included, and 2 (9.52%) cows were fair. Serum samples were collected, analyzed for anti-bovine TB antibody using RAT and iELISA. Also the herd was screened by CCTT. The tests were carried out twice, more than ten month interval, and twelve nasal swabs were taken within second survey. The first survey results revealed prevalence rate: 4 (19.04%) animals considered positive results (one positive and 3 suspected results) for CCTT, while the prevalence rate according to RAT was 10 (47.61%). The difference between the two prevalence rate was significant (McNemar chi-statistic = 4.50, p-value = 0.03) Kappa = 0.215 95% confidence interval: from -0.128 to 0.558;the strength of agreement is considered to be “fair”. The study interprets: sensitivity 30%;specificity 99%. The second survey results revealed prevalence rate according to CCTT was 4 (36.36%), while prevalence rate according to RAT was 5 (45.45%). The difference between the two prevalence was not significant (McNemar chi-statistic = 0.33, p-value = 0.56). Kappa = 0.441 95% confidence interval: from -0.087 to 0.968;the strength of agreement is considered to be “moderate”;sensitivity: 60%;specificity: 83%. All serum samples and nasal swabs gave negative results for iELISA and culturing respectively. The study concluded that RAT was highly specific, easy, labor and time saving, suggesting its use as screening test in bovine tuberculosis, and CCTT could be used to confirm positive animals screened by RAT, while there was no association between RAT, CCTT with body condition scores, iELISA and nasal swabs culture results.

High-field-induced electron detrapping in an AlGaN/GaN high electron mobility transistor

A step stress test is carried out to study the reliability characteristics of an AlGaN/GaN high electron mobility transistor（HEMT）.An anomalous critical drain-to-gate voltage with a negative temperature coefficient is observed in the stress sequence,beyond which the HEMT device starts to recover from degradation induced by early lower voltage stress.While the performance degradation featuring the drain current slump stems from electron trapping in the surface or bulk states during low-to-medium bias stress,the recovery is attributed to high field induced electron detrapping.The carrier detrapping mechanism could be helpful for lessening the trapping-related performance degradation of a GaN-based HEMT.

Normative Values of Cardio-Respiratory Endurance in Adults in Benin

Cardiorespiratory endurance is a determining factor in the assessment of the state of health of a person. Objective: To determine the reference values for cardiorespiratory endurance in Beninese adults. Methods: Prospective transversal study, with a descriptive and analytical aim. It was carried out on healthy adult subjects (18 to 50 years old), of Cotonou and Abomey cities, from October 2017 to May 2018, without clinically identifiable orthopedic, cardiorespiratory, osteoarticular or neuromotor impairment. These subjects performed three different cardio-respiratory endurance tests: The six-minute walk test (WT6), cycloergometer test (CT) and the step test (ST). Data processing and analysis were done using SPSS version 22 software. A linear regression model was used to establish the prediction equation of maximal oxygen uptake (VO2 max) with the WT6 data. The significance level chosen was 5%. Results: Subjects average age was 30.0 ± 9.8 years. It was especially men (54.20%), students (42.13%), with a normal corpulence (69.91%). At WT6, they walked 365 m to 798 m (557.1 ± 93.6 m) with extreme heart rates (EHR) of 67 to 189 (136.7 ± 19.0) beats per minute. At ST, the extreme powers developed were 2.7 watts/kg and 11.8 watts/kg (6.4 ± 1.8 watts/kg), with EHR of 99 to 204 (168.4 ± 15.4) beats per minute. The predictor equation of VO2 max by WT6 was function of the subject’s weight, age and sex (R = 0.73). Conclusion- Discussion: These normative values of cardio-respiratory endurance of Beninese subjects seem to be specific to them. An extension of the present study to a larger sample nevertheless seems desirable.