How driving duration influences drivers' visual behaviors and fatigue awareness: a naturalistic truck driving test study

AbstractBackground: Commercial truck drivers stay behind the wheel for long hours. Fatigue is thus a major safety concern among such long distance travelling drivers.Objectives: Primarily, the study explored the effects of driving duration on commercial truck drivers’ visual features and fatigue awareness. It also examined the association between visual variables and subjective level of fatigue.Methods: Participants of the study were 36 commercial truck drivers. During the study, the participants were grouped into nine on the basis of the differences in their age and were made to participate in the naturalistic driving test. In the driving test, the participants were asked to finish 2h, 3h, and 4h continuous driving tasks. Ten visual indicators and self awareness of fatigue level of the drivers were recorded during the driving hours. One-way ANOVA and Pearson product-moment correlation were used to analyze each visual indicator’s variation by age groups over time, and its association with subjective level of fatigue.Results: The statistical analysis revealed that continuous driving duration had a significant effect on changes of visual indicators and self-reported fatigue level. After 2h of driving, both the average closure duration value and average subjective fatigue level changed significantly. After 4h of driving, other than the average number of saccades and average pupil diameter, all of the driver’s visual indicators had a significant change. In addition, the change of fatigue level is positively associated with the variation of pupil diameter, fixation duration, blink frequency, blink duration, and closure duration. On the other hand, the change of fatigue level was negatively related to number of fixations, search angle, number of saccade, saccade speed, and saccade amplitude.Conclusion: Driving duration has a significant effect on driver’s visual variation and fatigue level. For commercial truck drivers, traffic laws and regulations should strictly control the amount of their continuous driving time. Moreover, driving fatigue can also be evaluated through the change rate of driver’s visual indicators. Awareness of the rate of change in their driving fatigue level alerts drivers to the risk of fatigue and rest moment. [Ethiop. J. Health Dev. 2018;32(1):36-45

Arabidopsis Transcriptome Analysis Reveals Key Roles of Melatonin in Plant Defense Systems

Melatonin is a ubiquitous molecule and exists across kingdoms including plant species. Studies on melatonin in plants have mainly focused on its physiological influence on growth and development, and on its biosynthesis. Much less attention has been drawn to its affect on genome-wide gene expression. To comprehensively investigate the role(s) of melatonin at the genomics level, we utilized mRNA-seq technology to analyze Arabidopsis plants subjected to a 16-hour 100 pM (low) and 1 mM (high) melatonin treatment. The expression profiles were analyzed to identify differentially expressed genes. 100 pM melatonin treatment significantly affected the expression of only 81 genes with 51 down-regulated and 30 up-regulated. However, 1 mM melatonin significantly altered 1308 genes with 566 up-regulated and 742 down-regulated. Not all genes altered by low melatonin were affected by high melatonin, indicating different roles of melatonin in regulation of plant growth and development under low and high concentrations. Furthermore, a large number of genes altered by melatonin were involved in plant stress defense. Transcript levels for many stress receptors, kinases, and stress-associated calcium signals were up-regulated. The majority of transcription factors identified were also involved in plant stress defense. Additionally, most identified genes in ABA, ET, SA and JA pathways were up-regulated, while genes pertaining to auxin responses and signaling, peroxidases, and those associated with cell wall synthesis and modifications were mostly down-regulated. Our results indicate critical roles of melatonin in plant defense against various environmental stresses, and provide a framework for functional analysis of genes in melatonin-mediated signaling pathways

An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts

Damage Identification Method with Structural Frequency Data from Modal Test

Testing and analysis technology based on vibration mode is a common method to structural health monitoring and checking. This paper deduces the damage factor used for structural damage evaluation based on test frequency of structure, makes a finite element numerical simulation using ANSYS software and model test to a pressure pipe. Here a stiffness reduction method is utilized to reproduce the damage state of a single-point and multiple-point, damage identification is carried out with a FEM model of redundant pipe. Meanwhile, a model experiment system is designed to validate the efficiency of damage factor with cutting-groove to simulate damage states. Numerical and experimental results show the proposed damage factor is theoretically breviate, simple realization and high-accuracy performance, therefore, it has a good usage prospect in the implementation of structural damage monitoring and identification

Metacommunity Structure of Zooplankton in River Networks: Roles of Environmental and Spatial Factors

Zooplankton in river systems have seldom been studied in the context of metacommunity ecology. Spatial factors (e.g., river connectivity, directionality, and man-made dams) may play a key role in influencing the metacommunity structure of rotifers because of their small body size and weak mobility. In contrast, local environmental factors (e.g., physicochemical habitat) may be more important to crustaceans due to their larger body size and stronger mobility. We sampled zooplankton and environmental factors during wet and dry seasons from 47 sites along the Ying River in China to assess the roles of the spatial and environmental factors in structuring zooplankton metacommunities. We used Moran’s eigenvector map and asymmetric eigenvector map to model the influences of river connectivity, directionality, and man-made dams on zooplankton metacommunity structure. We then used partial redundancy analysis to identify individual and interactive effects of spatial and environmental factors on both the entire zooplankton assemblages and two zooplankton groups of different body sizes and mobility. A total of 101 taxa were identified and taxa richness was higher in the wet season (72) than in the dry season (58). Zooplankton assemblages were primarily dominated by rotifers. For the dry season, environmental factors such as total nitrogen, water temperature, and pH explained a significant portion of variation in zooplankton community; river connectivity was more important than river directionality to zooplankton metacommunity structure. For the wet season, spatial factors were more influential than environmental factors such as dissolved oxygen and water transparency; river directionality played an important role in influencing the spatial structures of both environmental condition and zooplankton metacommunity. We also found significant effects of man-made dams on zooplankton metacommunity structure. Spatial factors are more influential in structuring small body size and weak mobility rotifer communities, while environmental factors are more important in determining the variation of crustaceans due to their larger body size and stronger mobility. We concluded that river connectivity and directionality should be considered as key factors for better understanding the spatial processes of planktonic passive dispersers in river networks. Our study provides new insight on understanding riverine zooplankton metacommunity ecology and contributes to the knowledge of river ecosystem health monitoring and management

Characterization of Pseudomonas spp. and Associated Proteolytic Properties in Raw Milk Stored at Low Temperatures

Milk spoilage is caused by the presence of proteolytic enzymes produced by Pseudomonas spp. during storage at low temperatures. The aim of this study was to identify Pseudomonas spp. in raw milk and investigate their associated proteolytic properties at low temperatures. Raw milk samples (n = 87) were collected from 87 bulk tanks in Shaanxi Province in China. Pseudomonas spp. were identified using Pseudomonas specific 16S, universal 16S rRNA sequencing, and rpoB gene sequencing. The proteolytic properties of Pseudomonas spp. were examined using milk agar, quantitative trinitrobenzenesulfonic acid assay, and by the presence of alkaline metallopeptidase gene (aprX). A total 143 isolates from all 87 samples were confirmed as Pseudomonas, and were identified as belonging to 14 Pseudomonas species. Of these, 40 (28.0%) isolates revealed proteolysis on milk agar at 2°C, 74 (51.8%) at 4°C, 104 (72.7%) at 7°C, and 102 (71.3%) at 10°C. However, proteolytic activity of 45 (31.5%) isolates exceeded 2 μmol of glycine equivalents per mL at 7°C, followed by 43 (30.1%) at 10°C, 18 (12.6%) at 4°C, and 7 (4.9%) at 2°C. The results reveal proteolytic activity of Pseudomonas spp. present in milk and their spoilage potential at different temperatures

Effects of Drought Stress and Rehydration on Physiological and Biochemical Properties of Four Oak Species in China

Quercus fabri Hance, Quercus serrata Thunb, Quercus acutissima Carruth, and Quercus variabilis BL are four Chinese oak species commonly used for forestation. To ensure the survival of seedlings, we first need to understand the differences in drought resistance of the four oak species at the seedling stage, and comprehensively evaluate their drought resistance capabilities. The four oak seedlings were divided into drought-rewatering treatment group and well watered samples (control group). For the seedlings of the drought-rewatering treatment group, drought stress lasting 31 days was used, and then re-watering for 5 days. The water parameters, osmotic solutes content, antioxidant enzyme activity and photosynthesis parameters of the seedlings in the two groups were measured every 5 days. Compared with the control group, the relative water content, water potential, net photosynthetic rate, transpiration rate, and stomatal conductance levels of the four oaks all showed a downward trend under continuous drought stress, and showed an upward trend after rehydration. The soluble protein, soluble sugar, proline, peroxidase, superoxide dismutase and catalase content of the four oaks increased first and then decreased under drought stress, and then increased after rehydration. The content of glycine betaine and malondialdehyde continued to increase, and gradually decreased after rehydration. The weight of each index was calculated by principal component analysis, and then the comprehensive evaluation of each index was carried out through the membership function method. The drought resistance levels of the four oak species were as follows: Q. serrata > Q. fabri > Q. variabilis > Q. acutissima