To improve the competitiveness of air transport, this study proposed a method for devising a differentiated comfort enhancement strategy and compared the comfort of aircraft and high‐speed trains ...(HST). Structural equation modeling (SEM) was used to analyze the similarities and differences in the factors influencing comfort in aircraft cabins and HST compartments. The results showed that comfort in wide‐body aircraft cabins was mainly influenced by “food & beverage” and “personal in‐flight entertainment” (personal IFE), whereas comfort in narrow‐body aircraft and HSTs was mainly influenced by the “passenger interface.” The results also showed no significant difference in the overall comfort evaluation of the passenger interface between narrow‐body aircraft and HSTs. Furthermore, aircraft passenger ratings were significantly lower than those of HST passengers with regard to “spaciousness,” “seat comfort,” and “seat and cabin and compartment aesthetics.” The study results suggest that given competition from HSTs, airlines should use different comfort enhancement strategies for wide‐body and narrow‐body aircraft cabins.
The Savage-Dickey density ratio is a specific expression of the Bayes factor when testing a precise (equality constrained) hypothesis against an unrestricted alternative. The expression greatly ...simplifies the computation of the Bayes factor at the cost of assuming a specific form of the prior under the precise hypothesis as a function of the unrestricted prior. A generalization was proposed by Verdinelli and Wasserman such that the priors can be freely specified under both hypotheses while keeping the computational advantage. This article presents an extension of this generalization when the hypothesis has equality as well as order constraints on the parameters of interest. The methodology is used for a constrained multivariate t-test using the JZS Bayes factor and a constrained hypothesis test under the multinomial model.
•We introduce a moderated t-statistic for performing group-level fMRI analysis.•The approach helps alleviate problems related to small sample sizes.•The approach outperforms several standard ...approaches.•An R-package is introduced for application of the method to fMRI data.
In recent years, there has been significant criticism of functional magnetic resonance imaging (fMRI) studies with small sample sizes. The argument is that such studies have low statistical power, as well as reduced likelihood for statistically significant results to be true effects. The prevalence of these studies has led to a situation where a large number of published results are not replicable and likely false. Despite this growing body of evidence, small sample fMRI studies continue to be regularly performed; likely due to the high cost of scanning. In this report we investigate the use of a moderated t-statistic for performing group-level fMRI analysis to help alleviate problems related to small sample sizes. The proposed approach, implemented in the popular R-package LIMMA (linear models for microarray data), has found wide usage in the genomics literature for dealing with similar issues. Utilizing task-based fMRI data from the Human Connectome Project (HCP), we compare the performance of the moderated t-statistic with the standard t-statistic, as well as the pseudo t-statistic commonly used in non-parametric fMRI analysis. We find that the moderated t-test significantly outperforms both alternative approaches for studies with sample sizes less than 40 subjects. Further, we find that the results were consistent both when using voxel-based and cluster-based thresholding. We also introduce an R-package, LIMMI (linear models for medical images), that provides a quick and convenient way to apply the method to fMRI data.
Bayesian estimation for 2 groups provides complete distributions of credible values for the effect size, group means and their difference, standard deviations and their difference, and the normality ...of the data. The method handles outliers. The decision rule can accept the null value (unlike traditional "t" tests) when certainty in the estimate is high (unlike Bayesian model comparison using Bayes factors). The method also yields precise estimates of statistical power for various research goals. The software and programs are free and run on Macintosh, Windows, and Linux platforms. (Contains 2 tables, 14 figures, and 1 footnote.)
We study the solar flare index (SFI) for the Solar Cycles 18 – 24. We find that SFI has deeper Gnevyshev gap (GG) in its first principal component than other atmospheric parameters. The GG is ...extremely clear especially in the even cycles.
The GG of the SFI appears about a half year later as a drop in the interplanetary magnetic field near the Earth and in the geomagnetic Ap-index. The instantaneous response of the magnetic field to solar flares, however, shows about two to three days after the eruption as a high, sharp peak in the cross-correlation of the SFI and Ap-index and as a lower peak in SFI vs. IMF B cross-correlation. We confirm these rapid responses using superposed-epoch analysis.
The most active flare cycles during 1944 – 2020 are Cycles 19 and 21. Cycle 18 has very strong SFI days as many as Cycle 22, but it has the least nonzero SFI days in the whole interval. Interestingly, Cycle 20 can be compared to Cycles 23 and 24 in its low flare activity, although it is located between the most active SFI cycles.
For gene expression data analysis, an important task is to identify genes that are differentially expressed between two or more groups. Nevertheless, as biological experiments are often measured with ...a relatively small number of samples, how to accurately estimate the variances of gene expression becomes a challenging issue. To tackle this problem, we introduce a regularized t$$ t $$ distribution and derive its statistical properties including the probability density function and the moment generating function. The noncentral regularized t$$ t $$ distribution is also introduced for computing the statistical power of hypothesis testing. For practical applications, we apply the regularized t$$ t $$ distribution to establish the null distribution of the regularized t$$ t $$ statistic, and then formulate it as a regularized t$$ t $$‐test for detecting the differentially expressed genes. Simulation studies and real data analysis show that our regularized t$$ t $$‐test performs much better than the Bayesian t$$ t $$‐test in the “limma” package, in particular when the sample sizes are small.
In recent years, concerns over some per- and polyfluorinated alkyl substances (PFAS) have grown steadily. PFAS are a large group of chemical substances with widely differing properties. While one ...class of PFAS, fluoropolymers, have been demonstrated to meet the OECD criteria for polymers of low concern during the in use phase of their lifecycle, questions remain regarding waste handling at the end of useful life for products containing fluoropolymers. To show that polytetrafluoroethylene (PTFE) can be almost fully transformed into fluorine (F) (as hydrofluoric acid (HF)) and to study the possible generation of low molecular weight per- and polyfluorinated alkyl substances (PFAS), PTFE combustion under typical waste incineration conditions at the BRENDA (German acronym for “Brennkammer mit Dampfkessel”) pilot plant at Karlsruhe Institute of Technology (KIT) was investigated. Results indicate that, within procedural quantitation limits, no statistically significant evidence was found that the PFAS studied were created during the incineration of PTFE. Therefore, municipal incineration of PTFE using best available technologies (BAT) is not a significant source of the studied PFAS and should be considered an acceptable form of waste treatment.
•Municipal incineration of PTFE shows no significant generation of studied PFAS.•Using pilot scale equipment and paired t-testing minimizes background interference.•PTFE produced mainly hydrofluoric acid and carbon dioxide during incineration.
This study aims 1) to compare repeated change of direction ability (rCODA) and bench press (BP) between low (A category, ≤2.5) and high (B category, ≥3.0) sport classes and 2) to analyse the ...relationships between rCODA and BP performance in a sample of wheelchair basketball (WB) players. Seventeen world-class WB players volunteered participated in this study. All the players undertook two tests: the repeated (x12) Modified Agility T-test (rMAT) to measure the rCODA and the movement velocity in a BP test. No significant differences were observed between categories in the rMAT and BP. For the total sample, BP variables with a mean propulsive velocity of 1 m·s
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) largely correlated with all the full rMAT outcomes (r>-0.625; p< 0.05). Having a better BP could be favourable to perform repeated efforts and this seems particularly relevant in fatigue conditions, and especially for the B category players.
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