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.
The goal of this paper is to analyse the innovation activity convergence process across European regions from 2002 to 2012. A novel methodology that allows either detection of overall convergence or ...endogenous identification of groups of regions was applied. The results support the club convergence hypothesis for explaining the convergence process of Europe's regions during the period analysed and seven innovation convergence clubs were identified. In addition, the research results indicate that initial regional R&D expenditure is the most relevant factor driving the formation of the convergence clubs after controlling for the effects of regional structural characteristics.
Resumen
El objetivo de este artículo es analizar el proceso de convergencia de las actividades de innovación en las regiones europeas desde 2002 a 2012. Se aplicó una metodología novedosa que permite la detección de la convergencia total o la identificación endógena de grupos de regiones. Los resultados apoyan la hipótesis de clubes de convergencia para explicar el proceso de convergencia de las regiones de Europa durante el período analizado y se identificaron siete clubes de convergencia en cuanto a innovación. Además, los resultados de la investigación indican que el gasto inicial en I+D regional es el factor más importante a la hora de impulsar la formación de los clubes de convergencia, una vez que se han controlado los efectos de las características estructurales regionales.
抄録:
本稿の目的は、2002~2012年のヨーロッパの地域全体における、イノベーション活動の収束の過程を分析することである。全体的収束の検出または地域の内因性同定のいずれかが可能な新しい方法を適用した。結果から、解析の対象期間におけるヨーロッパの地域の収束仮定を説明するクラブ収束仮設が支持され、7つのイノベーション収束クラブが確認された。さらに、結果から、地域の構造的特徴の影響を調整した後では、収束クラブの形成を促す最も重要な要因は、地域のはじめの研究開発資金であることが示された。
The present study has been undertaken with the purpose of investigating the critical success factors for the implementation of product lifecycle management (PLM) systems in manufacturing companies. ...Two exploratory case-based studies were conducted followed by a generalised study to establish the critical success factors for PLM systems' implementation in manufacturing firms. Hybrid multi-criteria decision-making methods were employed to identify the causal factors and prioritise them for the implementation of PLM systems in an automotive and aerospace firm. The priority of the factors has also been confirmed by executives from broader PLM domain through a confirmatory t-test. The identified critical success factors can be utilised as directive guidelines by manufacturing organisations for the successful implementation of PLM systems. Most researchers have studied only the technological aspects of PLM, while very few have discussed the success factors to PLM implementation. The present study is highlighting PLM as a management concept, supporting PLM systems implementation in organisations, and discussing the critical success factors for effective PLM systems implementation.
Transparent reporting is essential for the critical evaluation of studies. However, the reporting of statistical methods for studies in the biomedical sciences is often limited. This systematic ...review examines the quality of reporting for two statistical tests, t-tests and ANOVA, for papers published in a selection of physiology journals in June 2017. Of the 328 original research articles examined, 277 (84.5%) included an ANOVA or t-test or both. However, papers in our sample were routinely missing essential information about both types of tests: 213 papers (95% of the papers that used ANOVA) did not contain the information needed to determine what type of ANOVA was performed, and 26.7% of papers did not specify what post-hoc test was performed. Most papers also omitted the information needed to verify ANOVA results. Essential information about t-tests was also missing in many papers. We conclude by discussing measures that could be taken to improve the quality of reporting.
The objective of the current study was to assess the relative agility T-test as a measure of change of direction speed and establish normative data specifically for children aged 10-11. A sample of ...350 boys and 220 girls within the specified age range, with no medical history of disease, was randomly recruited from various schools. The mean and standard deviation, as well as the range of values, were determined for several variables including age, body mass, height, and BMI for both boys (n=350, age=10.83±0.38 years, body mass=34.42±5.61 kg, height=1.44±0.06 m, BMI=16.59±2.13 kg/m²) and girls (n=220, age=10.79±0.41 years, body mass=34.85±6.36 kg, height=1.44±0.07 m, BMI=16.61±2.15 kg/m²). The T-test, along with the FCMJ and 30mSS tests, were performed at least three times with a three-minute recovery period between trials and a five-minute recovery period between tests. Test-retest reliability of the T-test was evaluated using the intraclass correlation coefficient (ICC), which yielded values of 0.95 for girls and 0.97 for boys. Significant correlations were observed between the T-test and FCMJ as well as the 30mSS for girls (r=-0.384, p<0.0001 and r=0.416, p<0.0001, respectively) and for boys (r=-0.344, p<0.0001 and r=0.440, p<0.0001, respectively). The study provides percentile values that can be utilized to monitor the physical fitness levels of both girls and boys.
A practical solution based on the method of variance estimates recovery is proposed for the Behrens-Fisher problem. Unlike the classical solution, the proposed test is not based on the central limit ...theorem and, therefore, it can control Type I error well for small or moderate sample sizes. In this sense, it performs better than the most commonly used Welch's approximate t-test, which may be liberal for small or moderate sample sizes. On the other hand, the powers of the proposed test appears to be close to that of the Welch's approximate t-test and better than those of the Fisher's solution and the generalized p-value solution; the latter two have no fixed p-value and need to simulate. The proposed test has a meaningful interpretation within and not just across experiments. It can be a competitive alternative solution.
In some situations, for example in agriculture, biology, hydrology, and psychology, researchers wish to determine whether the relationship between response variable and predictor variables differs in ...two populations. In other words, we are interested in comparing two regression models for two independent datasets. In this work, we will use the parametric and nonparametric methods to establish hypothesis testing for the equality of two independent regression models. Then the simulation study is provided to investigate the performance of the proposed method.
Temperature and relative humidity are the most important factors affecting on human comfort. This Research test the monthly average temperature and relative humidity for some selected stations in ...Iraq, three stations (Baghdad - Mosul - Basra) to find the pattern covariance of the annual average of temperatures and relative humidity for the period of time (2000-2014) By using the Welch T-test or paired T- test, We find that the calculated value is greater than the tabular value in both stations (Baghdad - Mosul) and (Baghdad - Basra) for both temperatures and relative humidity, and this indicates an increasing trend in the average of temperature and relative humidity in two stations (Baghdad - Mosul) and (Baghdad - Basra), and since the main hypothesis is that there is a relationship between the two racists and the calculations prove that, so we reject the null hypothesis, which proves the validity of the main hypothesis, i.e. there is a relationship between temperature and humidity in these selected stations.
The present study is envisaged with an aim to highlight a novel approach of applying the statistical factorial design analysis (FDA) technique in radiation shielding design. In FDA, the estimated ...total dose rate (TDR) and concentration of elements in shielding material are termed as "Response" and "Factors." The impact on the response due to the change in the level of factors is defined as "Effects." Monte Carlo simulation (MCS) is performed using the MCNP4A code to compute the surface TDRs due to the coupled neutron-gamma field arising from the 740-GBq
241
Am-Be source housed inside a shielding container made of composite polymer (CP). The composition of CP is hydrogen, carbon, and oxygen with lead and natural boron as fillers. In the present work, the weight percent of hydrogen, carbon, and lead is optimized in the CP by minimizing the surface TDR at the exit of the shield, and a proposed CP (PCP) is obtained. For the first time, a detailed regression analysis is performed to develop a model linking TDR and the three factors, namely, hydrogen weight percent, carbon weight percent, and lead weight percent. Three levels of each factor are considered, and the impact due to the linear, quadratic, and interaction effects of the factors that influences the TDR is investigated using Student's t-test analysis. The results from the statistical analysis indicate that the weight percent of hydrogen and lead have a greater influence on TDR. The interaction effects arising out of the combination of hydrogen, carbon, and lead are observed to be negligible. Hence, the regression model is modified by dropping the statistically insignificant terms from the equation, and the new model has shown excellent correlation within ±1% of the estimated TDRs using MCS. The R
2
and R
2
Adj
values are found to be 0.99970 and 0.99966, which explains the computation power of the model. The model can be applied to compute the TDRs for any combinations of factors within the range of variability as studied in the present work. The shielding container made of PCP obtained from the present study provides a minimum of 20% reduction in volume and mass compared to the conventional high-density polyethylene and other polymer-based materials.
Recently, a mix of traditional and modern approaches have been proposed to detect brain abnormalities using bio‐signal/bio‐image‐assisted methods. In hospitals, most of the initial/scheduled ...assessments consider the bio‐signal‐based appraisal, due to its non‐invasive nature and low cost. Further, brain bio‐signal scans can be recorded using a single/multi‐channel electrode setup, which is further evaluated by an experienced doctor, as well as computer software, to identify the nature and severity of abnormality. In this paper, we describe the development of a system for computer supported detection (CSD) of schizophrenia using the electroencephalogram (EEG) signal collected with a 19‐channel electrode array. Schizophrenia is a mental illness that interferes with the way an individual thinks and behaves. It is characterised by psychotic symptoms such as hallucinations or delusions, negative symptoms such as decreased motivation or a lack of interest in daily activities and cognitive symptoms such challenges in processing information to make informed decisions or staying focused. This research has utilized 1142 EEGs (516 normal and 626 schizophrenia) with a frame length of 25 s (6250 samples) for investigation. The work initially converts the EEG signals to images using a spectrogram. Local configuration pattern features were extracted from the images thereafter, and 10‐fold validation technique was used wherein Student's t‐test and z‐score standardization were computed per fold. The highest accuracy of 97.20% was achieved with the K‐nearest neighbour (KNN) classifier. The results obtained confirm that the KNN classifier is helpful in the rapid detection of schizophrenia. This work is one of the first studies to extract local configuration pattern features from spectrogram images, yielding a high accuracy of 97.20%, with reduced computational complexity.
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