Strain gage system evaluation program

A program was conducted to determine the reliability of various strain gage systems when applied to rotating compressor blades in an aircraft gas turbine engine. A survey of current technology strain gage systems was conducted to provide a basis for selecting candidate systems for evaluation. Testing and evaluation was conducted in an F 100 engine. Sixty strain gage systems of seven different designs were installed on the first and third stages of an F 100 engine fan. Nineteen strain gage failures occurred during 62 hours of engine operation, for a survival rate of 68 percent. Of the failures, 16 occurred at blade-to-disk leadwire jumps (84 percent), two at a leadwire splice (11 percent), and one at a gage splice (5 percent). Effects of erosion, temperature, G-loading, and stress levels are discussed. Results of a post-test analysis of the individual components of each strain gage system are presented

Uncovering predictability in the evolution of the WTI oil futures curve

Accurately forecasting the price of oil, the world's most actively traded commodity, is of great importance to both academics and practitioners. We contribute by proposing a functional time series based method to model and forecast oil futures. Our approach boasts a number of theoretical and practical advantages including effectively exploiting underlying process dynamics missed by classical discrete approaches. We evaluate the finite-sample performance against established benchmarks using a model confidence set test. A realistic out-of-sample exercise provides strong support for the adoption of our approach with it residing in the superior set of models in all considered instances.Comment: 28 pages, 4 figures, to appear in European Financial Managemen

The bidirectional longitudinal association between depressive symptoms and HbA 1c : a systematic review and meta‐analysis

Aim To investigate whether there is a bidirectional longitudinal association of depression with HbA1c. Methods We conducted a systematic literature search in PubMed, PsycINFO, CINAHL and EMBASE for observational, longitudinal studies published from January 2000 to September 2020, assessing the association between depression and HbA1c in adults. We assessed study quality with the Newcastle-Ottawa-Scale. Pooled effect estimates were reported as partial correlation coefficients (rp) or odds ratios (OR). Results We retrieved 1,642 studies; 26 studies were included in the systematic review and eleven in the meta-analysis. Most studies (16/26) focused on type 2 diabetes. Study quality was rated as good (n=19), fair (n=2) and poor (n=5). Of the meta-analysed studies, six investigated the longitudinal association between self-reported depressive symptoms and HbA1c and five the reverse longitudinal association, with a combined sample size of n=48,793 and a mean follow-up of 2 years. Higher levels of baseline depressive symptoms were associated with subsequent higher levels of HbA1c (partial r=0.07;[95%CI0.03,0.12]; I238%). Higher baseline HbA1c values were also associated with 18% increased risk of (probable) depression (OR=1.18;[95%CI1.12,1.25]; I20.0%). Conclusions Our findings support a bidirectional longitudinal association between depressive symptoms and HbA1c. However, the observed effect sizes were small and future research in large-scale longitudinal studies is needed to confirm this association. Future studies should investigate the role of type of diabetes and depression, diabetes distress and diabetes self-management behaviours. Our results may have clinical implications, as depressive symptoms and HbA1c levels could be targeted concurrently in the prevention and treatment of diabetes and depression

Short-form measures of diabetes-related emotional distress: The Problem Areas in Diabetes Scale (PAID)-5 and PAID-1

Aims/hypothesis: We wanted to identify a five-item short form of the Problem Areas in Diabetes Scale and a single-item measure for rapid screening of diabetes-related emotional distress. Methods: Using an existing database of 1,153 patients with diabetes, we conducted a principal-components analysis to identify a set of five items and then conducted a reliability analysis and validity checks. From those five items, we identified the item with the strongest psychometric properties as a one-item screening tool. Results: We identified a reliable and valid short version of the Problem Areas in Diabetes Scale (PAID) comprising five of the emotional-distress questions of the full PAID items (PAID-5, with items 3, 6, 12, 16, 19). The PAID-5 has satisfactory sensitivity (94%) and specificity (89%) for recognition of diabetes-related emotional distress. We also identified a one-item screening tool, the PAID-1 (Question 12: Worrying about the future and the possibility of serious complications), which has concurrent sensitivity and specificity of about 80% for the recognition of diabetes-related emotional distress. Conclusions/ interpretation: The PAID-5 and PAID-1 appear to be psychometrically robust short-form measures of diabetes-related emotional distress.Centro de Endocrinología Experimental y Aplicad

AR and MA representation of partial autocorrelation functions, with applications

We prove a representation of the partial autocorrelation function (PACF), or the Verblunsky coefficients, of a stationary process in terms of the AR and MA coefficients. We apply it to show the asymptotic behaviour of the PACF. We also propose a new definition of short and long memory in terms of the PACF.Comment: Published in Probability Theory and Related Field

The Suppressor of AAC2 Lethality SAL1 Modulates Sensitivity of Heterologously Expressed Artemia ADP/ATP Carrier to Bongkrekate in Yeast

The ADP/ATP carrier protein (AAC) expressed in Artemia franciscana is refractory to bongkrekate. We generated two strains of Saccharomyces cerevisiae where AAC1 and AAC3 were inactivated and the AAC2 isoform was replaced with Artemia AAC containing a hemagglutinin tag (ArAAC-HA). In one of the strains the suppressor of ΔAAC2 lethality, SAL1, was also inactivated but a plasmid coding for yeast AAC2 was included, because the ArAACΔsal1Δ strain was lethal. In both strains ArAAC-HA was expressed and correctly localized to the mitochondria. Peptide sequencing of ArAAC expressed in Artemia and that expressed in the modified yeasts revealed identical amino acid sequences. The isolated mitochondria from both modified strains developed 85% of the membrane potential attained by mitochondria of control strains, and addition of ADP yielded bongkrekate-sensitive depolarizations implying acquired sensitivity of ArAAC-mediated adenine nucleotide exchange to this poison, independent from SAL1. However, growth of ArAAC-expressing yeasts in glycerol-containing media was arrested by bongkrekate only in the presence of SAL1. We conclude that the mitochondrial environment of yeasts relying on respiratory growth conferred sensitivity of ArAAC to bongkrekate in a SAL1-dependent manner. © 2013 Wysocka-Kapcinska et al

Not all mitochondrial carrier proteins support permeability transition pore formation: no involvement of uncoupling protein 1

The mPTP (mitochondrial permeability transition pore) is a non-specific channel that is formed in the mitochondrial inner membrane in response to several stimuli, including elevated levels of matrix calcium. The pore is proposed to be composed of the ANT (adenine nucleotide translocase), voltage-dependent anion channel and cyclophilin D. Knockout studies, however, have demonstrated that ANT is not essential for permeability transition, which has led to the proposal that other members of the mitochondrial carrier protein family may be able to play a similar function to ANT in pore formation. To investigate this possibility, we have studied the permeability transition properties of BAT (brown adipose tissue) mitochondria in which levels of the mitochondrial carrier protein, UCP1 (uncoupling protein 1), can exceed those of ANT. Using an improved spectroscopic assay, we have quantified mPTP formation in de-energized mitochondria from wild-type and Ucp1KO (Ucp1-knockout) mice and assessed the dependence of pore formation on UCP1. When correctly normalized for differences in mitochondrial morphology, we find that calcium-induced mPTP activity is the same in both types of mitochondria, with similar sensitivity to GDP (approximately 50% inhibited), although the portion sensitive to cyclosporin A is higher in mitochondria lacking UCP1 (approximately 80% inhibited, compared with approximately 60% in mitochondria containing UCP1). We conclude that UCP1 is not a component of the cyclosporin A-sensitive mPTP in BAT and that playing a role in mPTP formation is not a general characteristic of the mitochondrial carrier protein family but is, more likely, restricted to specific members including ANT

Short-form measures of diabetes-related emotional distress: The Problem Areas in Diabetes Scale (PAID)-5 and PAID-1

Aims/hypothesis: We wanted to identify a five-item short form of the Problem Areas in Diabetes Scale and a single-item measure for rapid screening of diabetes-related emotional distress. Methods: Using an existing database of 1,153 patients with diabetes, we conducted a principal-components analysis to identify a set of five items and then conducted a reliability analysis and validity checks. From those five items, we identified the item with the strongest psychometric properties as a one-item screening tool. Results: We identified a reliable and valid short version of the Problem Areas in Diabetes Scale (PAID) comprising five of the emotional-distress questions of the full PAID items (PAID-5, with items 3, 6, 12, 16, 19). The PAID-5 has satisfactory sensitivity (94%) and specificity (89%) for recognition of diabetes-related emotional distress. We also identified a one-item screening tool, the PAID-1 (Question 12: Worrying about the future and the possibility of serious complications), which has concurrent sensitivity and specificity of about 80% for the recognition of diabetes-related emotional distress. Conclusions/ interpretation: The PAID-5 and PAID-1 appear to be psychometrically robust short-form measures of diabetes-related emotional distress.Centro de Endocrinología Experimental y Aplicad

A study of data-driven momentum and disposition effects in the Chinese stock market by functional data analysis

We apply a functional data analysis approach to decompose the cross-sectional Fama–French three-factor model residuals in the Chinese stock market. Our results indicate that other than Fama–French three factors, there are two orthonormal asset pricing factors describing the behavioral biases in their historical performances: between winner and loser stocks, and extreme and mediocre-performing stocks, respectively. We explain these two factors through investors’ overreaction, overconfidence and the lead-lag effect. These findings empirically show the existence of momentum and disposition effects in the Chinese stock market. A buy-and-hold mean-variance optimized portfolio incorporating these two market anomalies boosts the Sharpe ratio to 1.27