Analysis of microstate features for Parkinson's disease based on reliability validation

BACKGROUND

Parkinson's disease (PD) is a disorder with abnormal changes in brain activity. The lack of objective indicators makes the assessment of PD progression difficult. Assessment of brain activity changes in PD may offer a potential solution.

NEW METHOD

Electroencephalogram (EEG) microstates reflect global dynamic changes in the brain. Therefore, we utilized microstates to assess changes in PD brain activity. However, the effect of epoch duration on the reliability of microstate analyses in PD is unclear. Thus, we first assessed the effect of data duration on the reliability of microstate topography and temporal features in PD and older healthy individuals. According to the reliability assessment, EEG epochs with high reliability were selected for microstate analysis in PD. Finally, we investigated the correlation between microstate features and clinical scales to determine whether these features could serve as objective indicators to evaluate PD progression.

RESULTS

Microstate analysis features that show high reliability for 3 min and above epoch durations. The topology of microstate D was significantly changed in PD compared to healthy controls, as well as the temporal features of microstates C and D. Additionally, the occurrence of C was negatively correlated with MoCA, and the duration of D was positively correlated with UPDRS.

COMPARISON WITH EXISTING METHOD(S)

High reliability of PD microstate features obtained by our approach.

CONCLUSION

EEG for PD microstate analysis should be at least 3 min. Microstate analysis is expected to provide new ideas and objective indicators for assessing Parkinson's disease progression in the clinical setting.

Metamodeling-based reliability analysis framework for activated sludge processes

The reliability of activated sludge processes will be adversely affected by alterations in wastewater production and pollutant loading foreseen due to population growth, urbanization, and climate change, as well as the tendency to amend environmental regulations to mandate stricter effluent quality standards to alleviate water pollution. Until now, there was no framework capable of effectively managing these multifaceted challenges in reliability analysis. Previous attempts conducted a low number of simulations leading to insufficient statistical significance to properly validate reliability quantification. A metamodeling-based reliability analysis framework for the activated sludge process is introduced to cope with alterations in wastewater production and pollutant loading, assesses the reliability under different effluent regulations, and leverages metamodels to conduct extensive simulation work, to estimate the reliability. All metamodels produced high-resolution results, enabling reliability estimation after 100 000 simulations. The framework effectively assessed the annual failure rates of various activated sludge facility designs under four regulations, demonstrating the impact of stricter effluent quality standards. Integrating metamodels for reliability analysis greatly lowers computational costs, making the framework a time and resource-efficient choice for quick decision-making in facility design.

Reliability-based analysis of horizontal curve design by evaluating the impact of vehicle automation on roadway departure crashes and safety performance

Roadway departure (RwD) crashes are significant safety concerns, especially at horizontal curves. The design of these curves plays a crucial role in mitigating RwD crashes. Thus, a thorough understanding of the interaction between driver behavior, vehicle automation, and geometric design is vital. Substantive safety, which emphasizes the inherent safety in a road's design and function, serves as the foundation of our approach. Building on this, the study employs a safe system approach to investigate the performance of horizontal curves under both non-automated and partially automated conditions, using a reliability-based analysis focusing on Stopping Sight Distance as the primary driver demand. Factors including Perception-Brake Time and Take-Over Time for automated vehicles are examined. The analysis covers horizontal curves, characterized by their geometric design and crash data. Our findings highlight a shift in the performance of horizontal curves under automation, emphasizing the need to consider automation in roadway design within the safe system approach. This study demonstrates how a reliability-based analysis can guide designers in making informed decisions regarding the geometric design of horizontal curves to reduce RwD crashes. To enhance transportation safety in the era of increasing automation, ongoing exploration of the relationships between driver behavior, automation, and road design is indispensable.

Identification of potential invasive alien species in Spain through horizon scanning

Invasive alien species have widespread impacts on native biodiversity and ecosystem services. Since the number of introductions worldwide is continuously rising, it is essential to prevent the entry, establishment and spread of new alien species through a systematic examination of future potential threats. Applying a three-step horizon scanning consensus method, we evaluated non-established alien species that could potentially arrive, establish and cause major ecological impact in Spain within the next 10 years. Overall, we identified 47 species with a very high risk (e.g. Oreochromis niloticus, Popillia japonica, Hemidactylus frenatus, Crassula helmsii or Halophila stipulacea), 61 with high risk, 93 with moderate risk, and 732 species with low risk. Many of the species categorized as very high or high risk to Spanish biodiversity are either already present in Europe and neighbouring countries or have a long invasive history elsewhere. This study provides an updated list of potential invasive alien species useful for prioritizing efforts and resources against their introduction. Compared to previous horizon scanning exercises in Spain, the current study screens potential invaders from a wider range of terrestrial, freshwater, and marine organisms, and can serve as a basis for more comprehensive risk analyses to improve management and increase the efficiency of the early warning and rapid response framework for invasive alien species. We also stress the usefulness of measuring agreement and consistency as two different properties of the reliability of expert scores, in order to more easily elaborate consensus ranked lists of potential invasive alien species.

Quantitative law and scenario-based forecasting of different land use expansion, based on reliability analysis in mountainous areas

The continuous high-intensity and disorderly expansion of construction land in mountainous areas threatens city development; consequently, the scientific guidance of its sustainable development has become a research hotspot. This work aimed to develop a new theoretical framework for predicting land expansion. Based on DMSP/OLS-Landsat 7 data correction from 2000 to 2019, to ensure data reliability, this study quantitatively analysed the expansion law of land-use and land-cover (LULC) in Huayuan, a typical mountainous area in China. Based on the land expansion law, the patch-generating land use simulation (PLUS) model was used to predict various types of LULCs in different scenarios. The results showed that (1) the reliability of LULC under multi-source spatio-temporal data correction reached more than 0.97. (2) The expansion law of industrial and mining land, urban living land, and traffic land is sprawl, while rural living land is enclaved and the expansion direction and intensity are obviously different. (3) The scale of land expansion in the natural-oriented scenario was significantly higher than that in the humanism-oriented scenario, with a higher value of 199.33 hm2. This study expands the case study of land use analysis and prediction, and provides scientific guidance for different land expansion planning, which can avoid the mismatch and waste of land resources. Furthermore, it also deepens the exploration of LULC identification reliability method and enriches the theory of different land use prediction in mountainous areas.

Reliability analysis of body sensor networks with correlated isolation groups

Body sensor networks (BSNs) are playing a crucial role in tackling arising challenges during the COVID-19 pandemic. This work contributes by modeling and analyzing the BSN reliability considering the effects of correlated functional dependence (FDEP) and random isolation time behavior. Particularly, the FDEP exists in BSNs where a relay is utilized to assist the communication between some biosensors and the sink device. When the relay malfunctions, the dependent biosensors may communicate directly with the sink for a limited, uncertain time. These biosensors then become isolated from the rest of the BSN when their remaining power depletes to the level insufficient to support the direct communication. Moreover, multiple biosensors sharing the same relay and a biosensor communicating with the sink via several alternative relays create correlations among different FDEP groups. In addition, the competition in the time domain exists between the local failure of the relay and the propagated failures of dependent biosensors. Both the correlation and competition complicate the reliability modeling and analysis of BSNs. This work proposes a combinatorial and analytical methodology to address both effects in the BSN reliability analysis. The proposed method is demonstrated using a detailed case study and verified using a continuous-time Markov chain method.

Study on potential energy curves and ro-vibrational energies of DT, HT and T2 molecules

Accurately monitoring and effectively controlling the tritium compounds based on their ro-vibrational energy structure are important issues in various nuclear systems. Because of their radioactivity, it is difficult to obtain the corresponding energies directly through experiments. In this paper, the potential energy curves and the corresponding ro-vibrational full spectrum of DT, HT and T₂ systems are derived by ab initio methods. However, it is difficult to verify the reliability of the calculated results due to the lack of direct experimental support. Therefore, a data-driven reliability analysis method is proposed, which can confirm the reliability by extracting information from the relevant calculations and multiple experimental data (the vibrational level, rotational level, and molar heat capacity) of similar systems (HD, H₂, D₂). The results show that: 1) The potential energy curves obtained by the ab initio method can provide the full ro-vibrational energy spectrum with an accuracy of approximately 10 cm^-1; 2) Macroscopic heat capacity information can be used to distinguish and calibrate the overall reliability of microscopic ro-vibrational energies; 3) For the isotopic energy level structure of hydrogen, the influence of isotopes is mainly mass effect.

Development of a new method to evaluate critical flux and system reliability based on particle properties in a membrane bioreactor

Membrane fouling occurs when the operating flux exceeds a certain point (i.e., critical flux). Critical flux has therefore been widely adopted to determine the initial operating flux in membrane bioreactor (MBR) processes. The flux steeping method currently used to measure the critical flux is time-consuming and uneconomical. This study was conducted to develop a novel approach for the evaluation of critical flux. Given that particle fouling is dominant during the initial fouling stage, we hypothesized that particle properties may be closely related to critical flux. A critical flux prediction model with an R² of 0.9 was therefore derived, which indicates that particle properties regulate critical flux. The results imply that most of the fouling potential during the early stages of operation is caused by SS, and that the formation of cakes that comprise large particles is the dominant fouling mechanism. The new method proposed in this study reduced the measurement cost and time to evaluate critical flux by 3.5-and 8 times, respectively, compared to the flux-stepping method. In terms of practical application, the applicability of the model equation was identified by system reliability analysis, which indicates that the system failure increases significantly as the standard deviation of the variables increases. This study demonstrated that the prediction of critical flux and system reliability can be achieved through particle characteristic measurement. A similar approach is expected to be employed in real MBR plants as an economical and convenient fouling control strategy to solve problems involving resource shortages.

Reliability analysis for the fractional-order circuit system subject to the uncertain random fractional-order model with Caputo type

•

We investigate the independent competing failure process of a RC system in an uncertain random environment.

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Continuous degradation of the system is subject to an uncertain fractional process.

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External shocks obey a random distribution given by real data.

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Two shock models that lead to hard failure are considered.

•

Analytical express the system reliability and perform numerical simulations.

Introduction

According to the competing failure theorem, the fractional-order Resistor Capacitance (RC) circuit system suffers not only from internal degradation but also from external shocks. However, due to the general differences of each failure type in the data availability and cognitive uncertainty, a better model is needed to describe the degradation process within the system. Also, a new reliability analysis method is needed for the circuit system under internal degradation and external shocks.

Objectives

To demonstrate this problem, this paper proposes a novel class of Caputo-type uncertain random fractional-order model that focuses on the reliability analysis of a fractional-order RC circuit system.

Methods

First, an uncertain Liu process is used to describe the internal degradation of soft faults and a stochastic process is used to describe the external random shocks of hard faults. Secondly, taking into account the correlation and competition among the fault types, an extreme shock model and a cumulative shock model are constructed, and chance theory is introduced to further explore the fault mechanisms, from which the corresponding reliability indices are derived. Finally, the predictor–corrector method is applied and numerical examples are given.

Results

This paper presents a reliability analysis of a fractional-order RC circuit system with internal failure obeying an uncertain process and external failure obeying a stochastic process, and gives the calculation of the reliability indexes for different cases and the corresponding numerical simulations.

Conclusion

A new competing failure model for a fractional-order RC circuit system is presented and analyzed for reliability, which is proved to be of practical importance by numerical simulations.

Reliability-based design and implementation of crow search algorithm for longitudinal dispersion coefficient estimation in rivers

The longitudinal dispersion coefficient (LDC) of river pollutants is considered as one of the prominent water quality parameters. In this regard, numerous research studies have been conducted in recent years, and various equations have been extracted based on hydrodynamic and geometric elements. LDC's estimated values obtained using different equations reveal a significant uncertainty due to this phenomenon's complexity. In the present study, the crow search algorithm (CSA) is applied to increase the equation's precision by employing evolutionary polynomial regression (EPR) to model an extensive amount of geometrical and hydraulic data. The results indicate that the CSA improves the performance of EPR in terms of R² (0.8), Willmott's index of agreement (0.93), Nash-Sutcliffe efficiency (0.77), and overall index (0.84). In addition, the reliability analysis of the proposed equation (i.e., CSA) reduced the failure probability (P_f) when the value of the failure state containing 50 to 600 m²/s is increasing for the P_f determination using the Monte Carlo simulation. The best-fitted function for correct failure probability prediction was the power with R² = 0.98 compared with linear and exponential functions.

OWAS inter-rater reliability

The Ovako Working posture Assessment System (OWAS) is a commonly used observational assessment method for determining the risk of work-related musculoskeletal disorders. OWAS claims to be suitable in the application for untrained persons but there is not enough evidence for this assumption. In this paper, inter-rater (inter-observer) reliability (agreement) is examined down to the level of individual postures and categories. For this purpose, the postures of 20 volunteers have been observed by 3 varying human raters in a laboratory setting and the inter-rater agreement against reference values was determined. A high agreement of over 98%(κ=0.98) was found for the postures of the arms but lower agreements were found for posture classification of the legs (66-97%,κ=0.85) and the upper body (80-96%,κ=0.85). No significant difference was found between raters with and without intense prior training in physical therapy. Consequently, the results confirm the general reliability of the OWAS method especially for raters with non-specialized background but suggests weaknesses in the reliable detection of a few particular postures.

Reliability of multi-purpose offshore-facilities: Present status and future direction in Australia

Sustainable use of the ocean for food and energy production is an emerging area of research in different countries around the world. This goal is pursued by the Australian aquaculture, offshore engineering and renewable energy industries, research organisations and the government through the "Blue Economy Cooperative Research Centre". To address the challenges of offshore food and energy production, leveraging the benefits of co-location, vertical integration, infrastructure and shared services, will be enabled through the development of novel Multi-Purpose Offshore-Platforms (MPOP). The structural integrity of the designed systems when being deployed in the harsh offshore environment is one of the main challenges in developing the MPOPs. Employing structural reliability analysis methods for assessing the structural safety of the novel aquaculture-MPOPs comes with different limitations. This review aims at shedding light on these limitations and discusses the current status and future directions for structural reliability analysis of a novel aquaculture-MPOP considering Australia's unique environment. To achieve this aim, challenges which exist at different stages of reliability assessment, from data collection and uncertainty quantification to load and structural modelling and reliability analysis implementation, are discussed. Furthermore, several solutions to these challenges are proposed based on the existing knowledge in other sectors, and particularly from the offshore oil and gas industry. Based on the identified gaps in the review process, potential areas for future research are introduced to enable a safer and more reliable operation of the MPOPs.

Towards a more inclusive and safe design of horizontal curves: Exploring the association between curve features, reliability measures, and safety

Reliability analysis has been advocated as a robust methodology to quantify the risk (known as the probability of non-compliance, P_nc) associated with design limitations such as insufficient sight distance on horizontal curves. This risk represents the probability that the current design (e.g., available sight distance) would fail to meet the requirements of the driving population (e.g., required sight distance). Although previous work has quantified the risk and established links between P_nc and safety, P_nc remains a statistical measure that is not informative enough to roadway designers. To overcome this limitation, the impacts of geometric design attributes on the P_nc as well as the direct and indirect (through the impacts on P_nc) impacts of those attributes on safety need to be modelled and understood. To achieve the aforementioned objective, this paper proposes the adoption of Structural Equation Modelling (SEM) to simultaneously model the relationships mentioned above using data collected on horizontal curves in Alberta, Canada. Light Detection And Ranging (LiDAR) data was first used to extract curve information and assess the 3D available sight distance on 244 curved highway segments. Reliability analysis was then used to quantify the P_nc associated with each curved segment. SEM was then used to test the impacts of curve geometric and traffic attributes on P_nc as well as the direct and indirect impacts those variables have on collision frequency. The results showed that P_nc, curve length, and traffic volume all had statistically significant effects on collision frequency. Curve attributes such as the curve's deflection angle and chord length had statistically significant impacts on P_nc. Both curve deflection angle and the chord length were also found to have an indirect influence on collisions, which was mediated through P_nc. The findings emphasize the importance of considering other curve attributes when designing horizontal curves instead of focusing entirely on the curve radius. The findings of this research provide insights into the indirect impacts of curve attributes of horizontal curves on safety. This could help designers consider curve features that have the highest impacts on non-compliance and safety levels.

Reliability analysis for multiple-stage solid waste management systems

Solid waste management (SWM) is a key issue for sustainable development and environment protection, and waste collection and transportation (WCT) is one of the most important steps in managing solid waste. A well-designed SWM system with optimised location and capacity of waste transfer stations (WTSs) and final disposal facilities (FDFs) plays a critical role in waste management. However, uncertainties are inevitable in a general SWM system, which could involve in any stage of the waste management. In this paper, we propose to use the reliability analysis method to manage the uncertainties for the multiple-stage SWM system. Furthermore, an optimisation model is developed to maximise the reliability of SWM systems by optimising the allocation of waste treatment demand between facilities. We also generated an event-tree to analyse the failure mode of the whole system. Finally, a case study was undertaken in Hong Kong to demonstrate the effectiveness of the methodology. The case study results indicate that the proposed method can: (i) estate the risk level of a SWM system, (ii) provide a solution to improve the system reliability or reduce the risk level, (iii) analyse the potential contributions of different policies on the reliability index, (iv) identify the critical facilities in a SWM system.

Multivariate models to investigate the relationship between collision risk and reliability outcomes on horizontal curves

This paper proposes a reliability-based framework to address the risk associated with limitations in the Available Sight Distance (ASD) on curved highway segments considering a three-dimensional (3D) sight distance computation approach. To facilitate this assessment, the ASD on horizontal curves was evaluated and an accurate inventory of curve attribute information was generated using LiDAR (Light Detection and Ranging) data in an automated and efficient manner. These datasets were then used to estimate the risk (probability of noncompliance, P_nc) associated with sight distance insufficiencies. Full Bayes multivariate Poisson log-normal safety performance functions were developed to relate the P_nc to the expected number of collisions. The results show that there was a statistically significant relationship between P_nc and collision frequency. There was also a significant correlation of 0.444 to 0.452 across collision severity levels indicating that curves with high Property-Damage-Only (PDO) collisions could be associated with higher injury and fatal (I + F) collisions. It was also found that P_nc had a greater impact on increasing PDO collisions than I + F collisions, suggesting that collisions associated with insufficient sight distance are likely to be less severe. The results of this analysis are expected to improve our understanding of the risks associated with deviations from design guidelines and quantitatively assess the safety margins due to these variations. The framework presented in this paper can be used to compare different design alternatives and investigate the influence of design deficiencies on collision occurrence across various severity levels.

Scale validation for the identification of falsified hand sanitizer: public and regulatory authorities perspectives from United Arab Emirates

Background

Since the time of declaration of global pandemic of COVID-19 by World Health Organization (WHO), falsified hand sanitizers surfaced regularly in markets, posing possible harm to public due to unlisted inclusion of methanol. The current research is an attempt to develop and validate a tool to document falsified hand sanitizer in the UAE community.

Method

A descriptive cross-sectional community-based study was conducted among 1280 randomly selected participants. Respondents were sent a web-based electronic link to the survey via email. Content validity, factor analyses and known group validity were used to develop and validate a new scale to identify falsified hand sanitizer. Test-retest reliability, internal consistency, item internal consistency (IIC), and intraclass correlation coefficients (ICCs) were used to assess the reliability of the scale. SPSS version 24 was used to conduct data analysis.

Results

A total of 1280 participants were enrolled in the study. The content validity index (CVI) was 0.83 with the final scale of 12 items. The Kaiser-Meyer-Olkin (KMO) value was 0.788, with the Bartlett test of sphericity achieving statistical significance (p < 0.001). Our factor analysis revealed a 3-component model. The 3-factor solution was confirmed by PCFA analysis and had associations with good fit values. The PCFA for NFI was 0.970, CFI 0.978, and TLI 0.967. All values were in excess of 0.95, with RMSEA values below 0.06 at 0.03; all of these values indicated a good model fit. The Cronbach’s alpha was good overall (0.867). All factors had a Cronbach’s alpha value in excess of 0.70. The instrument demonstrated that every item met the IIC correlation standard ≥0.40. The scale displayed good overall ICC statistics of 0.867 (95% CI 0.856–0.877) with statistical significance (p < 0.001). The scale’s test-retest reliability was assessed through correlation of the falsified hand sanitizer identification score of respondents at the two time points. The test-retest correlation coefficient was 0.770 (p value < 0.01). Participants with post-graduate education were more likely to identify the falsified hand sanitizer compared to those with high school education. (p < 0.001).

Conclusions

This study developed and validated a new scale for the measurement of falsified hand sanitizer. This is expected to improve and promote collaboration between the health regulators and the public and hereby encourage customer satisfaction and participation.

Assessing knee anatomy using Makoplasty software a case series of 99 knees

Background

Role of MAKOplasty software in determining femoral neck version, distal-femoral resection angle, tibial axis difference, distal-femoral rotation, medial/lateral tibial slope, and tibial tubercle alignment has yet to be fully explored.

Methods

Preoperative CT scans and plain films of 99 patients were obtained for each patient according to predetermined MAKO-protocol by four observers. Reliability analyses (Cronbach's Alpha-test) was performed to determine agreement between raters for angle measures.

Results

Anatomic measurements were similar to previously published literature, and cronbachs'alpha analysis demonstrated agreement amidst all observers.

Conclusion

MAKOplasty software produces similar results to anatomic measurements in planning for TKA with good reproducibility.

Amygdalar nuclei and hippocampal subfields on MRI: Test-retest reliability of automated volumetry across different MRI sites and vendors

BACKGROUND

The amygdala and the hippocampus are two limbic structures that play a critical role in cognition and behavior, however their manual segmentation and that of their smaller nuclei/subfields in multicenter datasets is time consuming and difficult due to the low contrast of standard MRI. Here, we assessed the reliability of the automated segmentation of amygdalar nuclei and hippocampal subfields across sites and vendors using FreeSurfer in two independent cohorts of older and younger healthy adults.

METHODS

Sixty-five healthy older (cohort 1) and 68 younger subjects (cohort 2), from the PharmaCog and CoRR consortia, underwent repeated 3D-T1 MRI (interval 1-90 days). Segmentation was performed using FreeSurfer v6.0. Reliability was assessed using volume reproducibility error (ε) and spatial overlapping coefficient (DICE) between test and retest session.

RESULTS

Significant MRI site and vendor effects (p ​< ​.05) were found in a few subfields/nuclei for the ε, while extensive effects were found for the DICE score of most subfields/nuclei. Reliability was strongly influenced by volume, as ε correlated negatively and DICE correlated positively with volume size of structures (absolute value of Spearman's r correlations >0.43, p ​< ​1.39E-36). In particular, volumes larger than 200 ​mm³ (for amygdalar nuclei) and 300 ​mm³ (for hippocampal subfields, except for molecular layer) had the best test-retest reproducibility (ε ​< ​5% and DICE ​> ​0.80).

CONCLUSION

Our results support the use of volumetric measures of larger amygdalar nuclei and hippocampal subfields in multisite MRI studies. These measures could be useful for disease tracking and assessment of efficacy in drug trials.

Nitrogen removal performance and needed area estimation of surface-flow constructed wetlands using a probabilistic approach

Pollutant concentrations in influents into constructed wetlands (CWs) are highly fluctuating and may vary over several orders of magnitude, leading to large uncertainties in removal performance assessment when using pollutant concentrations in the influent and effluent directly. Incorporating a probabilistic approach into removal performance assessment and needed area estimation of CWs could advantage decision making regarding wastewater treatment and engineering applications. A series of three-stage surface-flow CWs (SFCWs) were constructed for treating ammonium-rich swine wastewater. The surface removal rate and removal efficiency of ammonium nitrogen in the SFCWs using the probabilistic approach were 0.27-3.23 g m^-2 d^-1 and 43.0-99.9% (95% confidence interval (CI)), which were consistent with the deterministic approach (95% CI: 0.24-3.18 g m^-2 d^-1 and 70.4-99.9%). The needed SFCW area was estimated as 6.6 (95% CI: 1.4-17.8) to 29.7 (95% CI: 6.4-80.1) m² for required removal efficiency from 40% to 90% for 0.18 m³ d^-1 swine wastewater with different strengthens. For specific removal efficiency of 90%, the needed CW areas was 13.9 (95%CI: 4.9-42.7), 25.1 (95%CI: 5.9-66.0), 33.5 (95%CI: 13.5-87.1), and 40.8 (95%CI: 16.2-89.4) m² for influent ammonium loading rate of 0.18-2.7, 2.7-14.4, 14.4-36, and 36-60 g d^-1, respectively. The first-order removal constant of ammonium nitrogen decreased logarithmically with increasing influent and effluent concentration/loading rate in the SFCW units (p < 0.001), which was responsible for the needed SFCW areas covering a wide range. The reliability analysis confirmed the results from the probabilistic approach were appropriate. The present study shed new lights on the performance evaluation and design of CWs for treating wastewater with highly-fluctuating concentrations using a probabilistic approach.

Probabilistic, safety-explicit design of horizontal curves on two-lane rural highways based on reliability analysis of naturalistic driving data

The high collision rates on horizontal curves compared to other roadway elements make them one of the most critical elements in a transportation network. In this regard, it is important to develop models to predict the safety performance of the horizontal curves. A considerable number of studies have been conducted to develop safety performance functions based on several concepts such as geometric characteristics, design consistency, reliability analysis, and comfort threshold. However, these models do not account for all horizontal curve design criteria or consider several cases such as driving in adverse weather conditions or on pavement of low available friction. This paper develops a probabilistic, safety explicit approach of horizontal curve design using reliability analysis of four design criteria: vehicle stability, driver comfort, sight distance, and vehicle rollover. Two situations were considered in the analysis: driving in clear weather (dry pavement) and raining weather (wet pavement) to develop safety performance functions for annual and five-year collision frequency. Four types of regression models, Poisson, negative binomial, zero-inflated Poisson, and zero-inflated negative binomial, were used in the analysis. The AIC, BIC, and Vuong test were used in evaluating the developed models.

Load balanced scheduling and reliability modeling of grid transaction processing system using colored Petri nets

On-demand computing is a popular enterprise model in which the computing resources are made available to the users as needed. On-demand computing based transaction processing system which has grown rapidly in recent years is an information processing system with the stringent requirements of resources to meet the fluctuating demands. Concepts such as grid computing, utility computing, autonomic computing, and adaptive management seem very similar to the concept of on-demand computing. When demands of resources fluctuate, the system needs load balancing for the efficient utilization of the computational resources. Furthermore, scheduling is needed to assign the transactions to the appropriate resources. Thus, modeling of load balanced scheduling along with reliability analysis for this system is a challenging task. This paper presents the load balanced scheduling and reliability modeling in such an environment by using colored Petri nets (CPNs). CPNs which combine Petri nets with programming languages is a powerful modeling technique. The proposed CPN-based modeling pattern formally describes the process of transaction distribution and execution within the on-demand computing environment. Moreover, the CPN-based model uses the hierarchical modeling capability of CPNs, including different levels of abstraction (sub-modules). This helps easily handling and extending the model. Since, on-demand computing based transaction processing system executes a number of concurrent transactions. The CPN-based model is extended to express the concurrency, thus improving the reliability results. This paper takes the example of grid transaction processing (GTP) system with the problem of load balanced scheduling modeling and reliability evaluation.

Mechanical properties of experimental composites containing bioactive glass after artificial aging in water and ethanol

OBJECTIVES

To evaluate the effect of bioactive glass 45S5 (BG) in experimental composites on flexural strength (FS), flexural modulus (FM), modulus of resilience (MR), and material reliability after artificial aging in water for 1, 7, and 30 days, and an additional accelerated aging for 3 days in a 75 vol% ethanol-water solution.

MATERIALS AND METHODS

Five experimental light-curable composites were prepared with 0-40 wt% of BG and a total filler load of 70 wt%. The resinous matrix was Bis-GMA/TEGDMA in 60:40 by weight. Mechanical properties were evaluated using a three-point bending test (ISO/DIN 4049:1998) with n = 20. Weibull statistics were used to assess material reliability. Additionally, the degree of conversion (DC) was assessed 24 h post-cure using FT-Raman spectroscopy.

RESULTS

FS and FM decreased linearly as the amount of BG was increased. The ISO 4049 requirement for a minimum FS of 80 MPa was fulfilled in experimental composites with up to 20 wt% of BG. Degradation of FS and FM with artificial aging was more extensive in materials with higher BG amounts. MR decreased as a function of BG amount and artificial aging. Material reliability (Weibull modulus) was stable through aging for composites with up to 10 wt% of BG. DC was negatively influenced by the BG amount and ranged from 64 to 81%.

CONCLUSION

Increasing the amount of unsilanized BG fillers from 0 to 40 wt% resulted in a progressive decline in mechanical properties and a more extensive degradation during artificial aging.

CLINICAL RELEVANCE

Bioactive fillers diminished the mechanical properties in a dose-dependent manner.

A short, robust brain activation control task optimised for pharmacological fMRI studies

BACKGROUND

Functional magnetic resonance imaging (fMRI) is a popular method for examining pharmacological effects on the brain; however, the BOLD response is dependent on intact neurovascular coupling, and potentially modulated by a number of physiological factors. Pharmacological fMRI is therefore vulnerable to confounding effects of pharmacological probes on general physiology or neurovascular coupling. Controlling for such non-specific effects in pharmacological fMRI studies is therefore an important consideration, and there is an additional need for well-validated fMRI task paradigms that could be used to control for such effects, or for general testing purposes.

METHODS

We have developed two variants of a standardized control task that are short (5 minutes duration) simple (for both the subject and experimenter), widely applicable, and yield a number of readouts in a spatially diverse set of brain networks. The tasks consist of four functionally discrete three-second trial types (plus additional null trials) and contain visual, auditory, motor and cognitive (eye-movements, and working memory tasks in the two task variants) stimuli. Performance of the tasks was assessed in a group of 15 subjects scanned on two separate occasions, with test-retest reliability explicitly assessed using intra-class correlation coefficients.

RESULTS

Both tasks produced robust patterns of brain activation in the expected brain regions, and region of interest-derived reliability coefficients for the tasks were generally high, with four out of eight task conditions rated as 'excellent' or 'good', and only one out of eight rated as 'poor'. Median values in the voxel-wise reliability measures were also >0.7 for all task conditions, and therefore classed as 'excellent' or 'good'. The spatial concordance between the most highly activated voxels and those with the highest reliability coefficients was greater for the sensory (auditory, visual) conditions than the other (motor, cognitive) conditions.

DISCUSSION

Either of the two task variants would be suitable for use as a control task in future pharmacological fMRI studies or for any other investigation where a short, reliable, basic task paradigm is required. Stimulus code is available online for re-use by the scientific community.

An innovative solution to reduce muscle deformation during ultrasonography data collection

BACKGROUND

3D freehand ultrasound enables the creation of volumetric data. The acquisition of morphological features, such as muscle volume, is influenced by the variations in force applied to the skin with the ultrasound probe. To minimise the deformations, a concave-shaped plastic mount combined with a custom-shaped gel pad was developed for the ultrasound head, named Portico. This study analyses to what extent the Portico reduces muscle deformation and corresponding errors in estimating muscle volume.

METHOD

Twenty medial gastrocnemius (MG) muscles were assessed (10 from typically developing children; 10 from children with spastic cerebral palsy). Two repetitions were acquired in each of the following approaches: (1) with the lower leg submerged in a water tank as a non-deformed reference; (2) probe-on-skin (PoS) as the conventional approach and (3) the newly introduced Portico. PoS and Portico data were registered with respect to the ones corresponding in a water tank. An in-house software package (Py3DFreeHandUS) was used to process the data and MG volume was estimated using MeVisLab. The minimal detectable change (MDC) was calculated.

RESULTS

With respect to the PoS approach, the Portico reduced muscle deformation by 46%. For both the typically developing and spastic cerebral palsy cohorts, lower MDCs were found when using the Portico.

DISCUSSION

Despite the improvements, the Portico did not yield statistically more reliable MG volume estimations than the traditional PoS approach. Further improvement can be attained by optimising the fit between the gel pad and the curvature of the limb, using a larger choice of Portico geometries.

Evaluation of the palliative symptom burden score (PSBS) in a specialised palliative care unit of a university medical centre - a longitudinal study

Background

The implementation of standardised, valid and reliable measurements in palliative care is subject to practical and methodological challenges. One aspect of ongoing discussion is the value of systematic proxy-based assessment of symptom burden in palliative care. In 2011, an expert-developed proxy-based instrument for the assessment of symptom burden in palliative patients, the Palliative Symptom Burden Score (PSBS), was implemented at the Specialised Palliative Care Unit of the University Medical Centre in Dusseldorf, Germany. The present study investigated its feasibility, acceptance and psychometric properties.

Methods

The PSBS was rated by nursing staff three times a day over 5 years (N = 820 patients). Feasibility and nurses’ acceptance of PSBS were analysed. Structural validity was investigated by principal component analysis. Construct validity was examined via cross-validation with the Hospice and Palliative Care Evaluation checklist. Discriminative validity of the PSBS was analysed by means of Kruskal-Wallis test of patients’ performance score. Reliability of the PSBS was evaluated by internal consistency analysis, test-retest and split-half-reliability. Inter-rater reliability was investigated by observer agreement of nurses’ ratings of symptom burden within a day. Sensitivity to change was analysed by Wilcoxon test with repeated measures of the PSBS before and after palliative complex treatment.

Results

A high degree of acceptance and the feasibility of a high-frequency proxy-based symptom burden assessment approach were demonstrated. There were low rates of missing values and no indications of the adoption of prior ratings. PSBS in its present form demonstrates good structural and construct validity (r_s = .27–.79, p’s < .001) and high sensitivity to changes in symptom burden (p’s < .01, except sweating), but unsatisfactory reliability (α = .41–.67; test-retest: r_{s =} .30–.88; p’s < .001; split-half: r_s = .69; p < .001; inter-rater: n.s.).

Conclusions

The study presents a framework for the post hoc validation of an already existing documentation tool in palliative care. This study supports the notion that PSBS might not be reflective of an overall construct and will therefore require further development and critical comparison to other already established symptom burden instruments in palliative care.

Reliability and validity analysis of the open-source Chinese Foot and Ankle Outcome Score (FAOS)

AIM

Develop the first reliable and validated open-source outcome scoring system in the Chinese language for foot and ankle problems.

METHODS

Translation of the English FAOS into Chinese following regular protocols. First, two forward-translations were created separately, these were then combined into a preliminary version by an expert committee, and was subsequently back-translated into English. The process was repeated until the original and back translations were congruent. This version was then field tested on actual patients who provided feedback for modification. The final Chinese FAOS version was then tested for reliability and validity. Reliability analysis was performed on 20 subjects while validity analysis was performed on 50 subjects. Tools used to validate the Chinese FAOS were the SF36 and Pain Numeric Rating Scale (NRS). Internal consistency between the FAOS subgroups was measured using Cronbach's alpha. Spearman's correlation was calculated between each subgroup in the FAOS, SF36 and NRS.

RESULTS

The Chinese FAOS passed both reliability and validity testing; meaning it is reliable, internally consistent and correlates positively with the SF36 and the NRS.

DISCUSSION AND CONCLUSIONS

The Chinese FAOS is a free, open-source scoring system that can be used to provide a relatively standardised outcome measure for foot and ankle studies.

A computational study of global optimization solvers on two trust region subproblems

One of the relevant research topics to which Chris Floudas contributed was quadratically constrained quadratic programming (QCQP). This paper considers one of the simplest hard cases of QCQP, the two trust region subproblem (TTRS). In this case, one needs to minimize a quadratic function constrained by the intersection of two ellipsoids. The Lagrangian dual of the TTRS is a semidefinite program (SDP) and this result has been extensively used to solve the problem efficiently. We focus on numerical aspects of branch-and-bound solvers with three goals in mind. We provide (i) a detailed analysis of the ability of state-of-the-art solvers to complete the global search for a solution, (ii) a quantitative approach for measuring the cluster effect on each solver and (iii) a comparison between the branch-and-bound and the SDP approaches. We perform the numerical experiments on a set of 212 challenging problems provided by Kurt Anstreicher. Our findings indicate that SDP relaxations and branch-and-bound have orthogonal difficulties, thus pointing to a possible benefit of a combined method. The following solvers were selected for the experiments: Antigone 1.1, Baron 16.12.7, Lindo Global 10.0, Couenne 0.5 and SCIP 3.2.

Reliability of a clinical 3D freehand ultrasound technique: Analyses on healthy and pathological muscles

BACKGROUND AND OBJECTIVE

3D freehand Ultrasonography is a medical imaging technique that can be used to measure muscle and tendon morphological and structural properties, including volume, lengths and echo-intensity. These properties are clinically relevant in neurological disorders such as spastic cerebral palsy to monitor disease progression and evaluate the effect of treatment. This study presents a methodology for extracting these parameters along with a clinical reliability analysis for the data acquisition and processing.

METHODS

The medial gastrocnemius muscles and Achilles tendon of 10 typically developing children and 10 children with spastic cerebral palsy were assessed. An open-source in-house software library developed in Python (Py3DFreeHandUS) was used to reconstruct, into one 3D data set, the data simultaneously acquired from an US machine and a motion tracking system. US images were manually segmented and linearly interpolated by means of a new simplified approach which involved sequentially decreasing the total number of images used for muscle border segmentation from 100% to 5%. Acquisition and processing reliability was defined based on repeated measures from different data processers and from different data acquirers, respectively.

RESULTS

When only 10% of the US images were outlined, there was an average underestimation of muscle volume of 1.1% and 1.6% with respect the computation of all the available images, for the typically developing and spastic cerebral palsy groups, respectively. For both groups, the reliability was higher for data processing than for data acquisition. High inter-class correlation coefficient values were found for processing and acquisition reliability, with worst case values of 0.89 and 0.61, respectively. The standard error of measurement, expressed as a percentage of the average volumes, was smaller than 2.6 ml (4.8%) in all cases.

CONCLUSIONS

The present analysis demonstrates the effectiveness of applying 3D freehand ultrasonography in a clinical setting for analysing healthy and pathological paediatric muscle.

Multi-mode reliability-based design of horizontal curves

Recently, reliability analysis has been advocated as an effective approach to account for uncertainty in the geometric design process and to evaluate the risk associated with a particular design. In this approach, a risk measure (e.g. probability of noncompliance) is calculated to represent the probability that a specific design would not meet standard requirements. The majority of previous applications of reliability analysis in geometric design focused on evaluating the probability of noncompliance for only one mode of noncompliance such as insufficient sight distance. However, in many design situations, more than one mode of noncompliance may be present (e.g. insufficient sight distance and vehicle skidding at horizontal curves). In these situations, utilizing a multi-mode reliability approach that considers more than one failure (noncompliance) mode is required. The main objective of this paper is to demonstrate the application of multi-mode (system) reliability analysis to the design of horizontal curves. The process is demonstrated by a case study of Sea-to-Sky Highway located between Vancouver and Whistler, in southern British Columbia, Canada. Two noncompliance modes were considered: insufficient sight distance and vehicle skidding. The results show the importance of accounting for several noncompliance modes in the reliability model. The system reliability concept could be used in future studies to calibrate the design of various design elements in order to achieve consistent safety levels based on all possible modes of noncompliance.

Evaluating the safety risk of roadside features for rural two-lane roads using reliability analysis

The severity of roadway departure crashes mainly depends on the roadside features, including the sideslope, fixed-object density, offset from fixed objects, and shoulder width. Common engineering countermeasures to improve roadside safety include: cross section improvements, hazard removal or modification, and delineation. It is not always feasible to maintain an object-free and smooth roadside clear zone as recommended in design guidelines. Currently, clear zone width and sideslope are used to determine roadside hazard ratings (RHRs) to quantify the roadside safety of rural two-lane roadways on a seven-point pictorial scale. Since these two variables are continuous and can be treated as random, probabilistic analysis can be applied as an alternative method to address existing uncertainties. Specifically, using reliability analysis, it is possible to quantify roadside safety levels by treating the clear zone width and sideslope as two continuous, rather than discrete, variables. The objective of this manuscript is to present a new approach for defining the reliability index for measuring roadside safety on rural two-lane roads. To evaluate the proposed approach, we gathered five years (2009-2013) of Illinois run-off-road (ROR) crash data and identified the roadside features (i.e., clear zone widths and sideslopes) of 4500 300ft roadway segments. Based on the obtained results, we confirm that reliability indices can serve as indicators to gauge safety levels, such that the greater the reliability index value, the lower the ROR crash rate.

Assessing the stochastic variability of the Benefit-Cost ratio in roadway safety management

Road Agencies set quantitative targets and adopt related road safety strategies within the priorities and the available resources at the time of an economic crisis. In this framework, benefit-cost analyses (BCA) are carried out to support the decision making process and alternative measures are ranked according to their expected benefit and benefit-cost ratio calculated using a Safety Performance Function (SPF) and Crash Modification Factors (CMFs) as predictors of future safety performances. Due to the variance of CMFs and crash frequency we are uncertain what the benefits of some future actions will be. The chance of making wrong decisions depends on the size of the standard deviation of the probability distribution of the considered stochastic variables. To deal with the uncertainty inherent in the decision making process, a reliability based assessment of benefits must be performed introducing a stochastic approach. In the paper the variability of the CMFs, the predicted number of crashes and the crash costs are taken into account in a reliability based BCA to address improvements and issues of an accurate probabilistic approach when compared to the deterministic results or other approximated procedures. A case study is presented comparing different safety countermeasures selected to reduce crash frequency and severity on sharp curves in motorways. These measures include retrofitting of old safety barriers, delineation systems and shoulder rumble strips. The methodology was applied using the Monte Carlo simulations to calculate the probability of failure of BCA statements. Results and comparisons with alternative approaches, like the one proposed in the HSM, are presented showing remarkable differences in the evaluation of outcomes which can be achieved.

Spine Instability Neoplastic Score: agreement across different medical and surgical specialties

BACKGROUND CONTEXT

Spinal instability is an acknowledged complication of spinal metastases; in spite of recent suggested criteria, it is not clearly defined in the literature.

PURPOSE

This study aimed to assess intra and interobserver agreement when using the Spine Instability Neoplastic Score (SINS) by all physicians involved in its management.

STUDY DESIGN

Independent multicenter reliability study for the recently created SINS, undertaken with a panel of medical oncologists, neurosurgeons, radiologists, orthopedic surgeons, and radiation oncologists, was carried out.

PATIENT SAMPLE

Ninety patients with biopsy-proven spinal metastases and magnetic resonance imaging, reviewed at the multidisciplinary tumor board of our institution, were included.

OUTCOME MEASURES

Intraclass correlation coefficient (ICC) was used for SINS score agreement. Fleiss kappa statistic was used to assess agreement on the location of the most affected vertebral level; agreement on the SINS category ("stable," "potentially stable," or "unstable"); and overall agreement with the classification established by tumor board.

METHODS

Clinical data and imaging were provided to 83 specialists in 44 hospitals across 14 Spanish regions. No assessment criteria were pre-established. Each clinician assessed the SINS score twice, with a minimum 6-week interval. Clinicians were blinded to assessments made by other specialists and to their own previous assessment. Subgroup analyses were performed by clinicians' specialty, experience (≤7, 8-13, ≥14 years), and hospital category (four levels according to size and complexity). This study was supported by Kovacs Foundation.

RESULTS

Intra and interobserver agreement on the location of the most affected levels was "almost perfect" (κ>0.94). Intra-observer agreement on the SINS score was "excellent" (ICC=0.77), whereas interobserver agreement was "moderate" (ICC=0.55). Intra-observer agreement in SINS category was "substantial" (k=0.61), whereas interobserver agreement was "moderate" (k=0.42). Overall agreement with the tumor board classification was "substantial" (κ=0.61). Results were similar across specialties, years of experience, and hospital category.

CONCLUSIONS

Agreement on the assessment of metastatic spine instability is moderate. The SINS can help improve communication among clinicians in oncology care.

Reliability analysis of nutrient removal from stormwater runoff with green sorption media under varying influent conditions

To support nutrient removal, various stormwater treatment technologies have been developed via the use of green materials, such as sawdust, tire crumbs, sand, clay, sulfur, and limestone, as typical constituents of filter media mixes. These materials aid in the physiochemical sorption and precipitation of orthophosphates as well as in the biological transformation of ammonia, nitrates and nitrites. However, these processes are dependent upon influent conditions such as hydraulic residence time, influent orthophosphate concentrations, and other chemical species present in the inflow. This study aims to compare the physiochemical removal of orthophosphate by isotherm and column tests under differing influent conditions to realize the reliability of orthophosphate removal process with the aid of green sorption media. The green sorption media of interest in this study is composed of a 5:2:2:1 (by volume) mixture of cement sand, tire crumb, fine expanded clay, and limestone. Scenarios of manipulating the hydraulic residence time of the water from 18 min and 60 min, the influent dissolved phosphorus concentrations of 1.0 mg·L(-1) and 0.5 mg·L(-1), and influent water types of distilled and pond water, were all investigated in the column tests. Experimental data were compared with the outputs from the Thomas Model based on orthophosphate removal to shed light on the equilibrium condition versus kinetic situation. With ANOVA tests, significant differences were confirmed between the experimental data sets of the breakthrough curves in the column tests. SEM imaging analysis helps to deepen the understanding of pore structures and pore networks of meta-materials being used in the green sorption media. Life expectancy curves derived from the output of Thomas Model may be applicable for future system design of engineering processes.

The Spine Instability Neoplastic Score: an independent reliability and reproducibility analysis

BACKGROUND

Metastatic vertebral instability has not yet been clearly defined in the literature; there still exists a paucity of reliable criteria to assess the risk of vertebral collapse.

PURPOSE

We performed an independent interobserver and intraobserver agreement evaluation of the Spine Instability Neoplastic Score (SINS) and correlated the score with selected clinical cases and the treatment they received.

STUDY DESIGN

Independent reliability study for the newly created SINS.

PATIENT SAMPLE

Thirty patients who underwent either radiotherapy alone or surgery followed by radiotherapy were randomly selected from the orthopedic surgery and radiotherapy department's databases.

OUTCOME MEASURES

Patients were rated and classified for spinal stability using SINS. Intraclass correlation coefficient (ICC) and Fleiss's kappa measures were occupied for reliability analysis.

METHODS

Patients who underwent either radiotherapy alone or surgery followed by radiotherapy were randomly selected and classified for spinal stability using the SINS by orthopedic surgeons and nonorthopedic oncology specialists. ICC and Fleiss's kappa were calculated for inter- and intraobserver agreement. A comparative analysis of SINS and the actual management was also conducted.

RESULTS

Interobserver ICC reliability for the SINS was 0.79; κ values for location, pain, bone quality, alignment, vertebral body collapse, and posterolateral involvement were 0.81, 0.58, 0.21, 0.45, 0.42, and 0.29 respectively. Intraobserver ICC for the SINS scores was 0.96; ICC values for the same components were 0.98, 0.98, 0.87, 0.88, 0.92, and 0.86, respectively. Potentially unstable lesions (SINS score≥7) were operated on in 62.5%.

CONCLUSIONS

SINS seem to be a reproducible tool that could be used equally by multiple specialists to estimate metastatic vertebral stability; however, prospective clinical validation is still pending.