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This paper presents a series of investigative studies, mainly parametric and numerical, into various issues related to the practical application of the wave propagation (WP) technique in monitoring of concrete curing using smart material (PZT). This paper is an extension of a range of experimental studies presented in the authors’ recent publication. Coupled field finite element (FE) simulation of the PZT-structure interaction in WP technique is conducted on mortar and concrete specimens. Identification of the pressure wave (P-wave) and the surface wave (R-wave) velocities simulated in the FE model is attempted. Results are found to be matching closely with the experiment. The verified FE model, together with the theoretical model are then used to perform parametric study on selected factors related to the practical application of the technique, in particular those uncontrollable in the experiment, including the dynamic modulus of elasticity, the Poisson’s ratio and the damping coefficient. Further experimental and analytical studies on the effect of varying temperature and humidity are also presented. A semi-analytical model previously proposed by the authors is finally adopted to generate a strength calibration chart for concrete with different coarse aggregates. The theoretical and FE models are proven to be useful alternatives to the experiment, which can be used in future design and optimization of the PZT based WP technique in monitoring of concrete curing. [ABSTRACT FROM AUTHOR]

Rapid economic growth and high urbanization rates create an urgent need for more space in major cities in China. Further development of underground spaces (UGS) is a viable solution that the Chinese government is promoting. For instance, the 13th 5-year Plan for Urban Underground Space Planning suggests that a comprehensive system for UGS planning and management should be established in at least 50% of Chinese cities by 2020. It is thus imperative to better understand how the architectural and engineering aspects of UGS affect human worker’s performance, well-being, health, and preferences. The present study reports a comprehensive examination of spaces and occupants of UGS in four major Chinese cities (Beijing, Shanghai, Nanjing and Fuzhou). We investigated thermal comfort conditions in UGS without heating and cooling, and estimated the potential of energy saving during transitional seasons. The results indicate that local climate – and especially the humidity level - is a key factor affecting the thermal behaviour of underground structures. In-depth interviews with workers in UGS indicated that immediate access to above ground greenery, indoor plants, and individual control over the environment compensate for a windowless workspace, and those working in UGS did not perceive to have any sleep disturbances. Previous experience with UGS improved the perception of current underground environments. UGS might even be appreciated as working environments with a good acoustic quality. Overall, the present study challenges the uniformity of standards for the construction of UGS, as it suggests that both climatic conditions as well as user preferences should be taken into account. [ABSTRACT FROM AUTHOR]

Smart piezoelectric material, namely, the Lead Zirconate Titanate (PZT) has recently found its application in concrete curing and strength development monitoring using the wave propagation (WP) technique. Real-life application of this technique is sometimes questioned as various practical issues have not been attended. In this paper, a series of experimental studies are performed to investigate a range of practical issues related to the application of this technique, in an attempt to reduce the gap between laboratory studies and real-life applications. Issues such as the consistency of wave velocities and repeatability of the sensor’s electrical signatures, the optimum frequency of actuation, the effect of PZT transducer’s spacing and sizes, the waveform of actuation signatures, the effect of input voltage amplification, the effect of different surface roughness, the environmental effect and the effect of different types of coarse aggregates are experimentally studied. Results showed that 5-peaks sinusoidal tone burst actuated at 30 kHz or 120 kHz are preferred input voltage. Spacing of transducers should be approximately 90 mm. Smooth and even surface of the host structure is preferred for bonding. The WP technique is found to be reliable and its performance is consistent across different specimens up to a period of 365 days. It is also capable of differentiating the strength concrete with different types of coarse aggregate. Studies conducted in this paper provide basic understanding into various practical issues, which is expected to serve as guidelines to future development, design, optimization and commercialization of a more effective PZT based WP technique in monitoring of concrete curing. [ABSTRACT FROM AUTHOR]

Working in underground spaces appears to be a possible solution for urban areas with lack of space or areas characterised by extremes of temperature. Besides pure engineering questions, it is also critical to understand the relationship between the architectural specificities of underground spaces and human behaviour and performance. Research to date has provided preliminary evidence on this question. Yet, during the last decade, contemporary cognitive neuroscience, experimental psychology and behavioural science have made impressive progress in the measurement, monitoring and understanding of human cognition and behaviour. These novel approaches offer advanced tools to study the human brain, body and mind; other disciplines (economics, political science, ergonomics and, recently, architecture) have successfully adopted these methods. The aim of the present paper is to introduce these concepts to the research community who studies the effects of underground work and offer practical examples of how these methods can be employed to understand crucial problems related to “underground psychology”. These new conceptual tools enable reliable isolation of various cognitive functions in a quantifiable way; identification of individual differences in responses to the environment; uncovering of underlying motivational factors; and establishment of a more mechanistic explanation of human behaviour. Cognitive neuroscience inspired methods offer a new exciting, comprehensive, more objective, and systematic examination of human behaviour in underground spaces and open new possibilities for identification of effective interventional strategies to improve the design of modern underground environments. [ABSTRACT FROM AUTHOR]

With growing population in urban areas, the problem of lacking space is becoming more prominent. Thus, the development of underground space has increasingly gained attention as a viable solution. Social aspects, such as social behavior and attitudes toward underground spaces could act as both facilitators and inhibitors toward the adoption of underground spaces. Here we review, present and discuss the major social parameters associated with working in underground spaces. Our research overview identified three major themes that pervade existing literature: attitudes and perception; social behavior; and the impact of environmental attributes of underground spaces. Yet, we also notice that the social and cultural elements associated with underground spaces have remained largely unexplored, with previous research being of more of a qualitative character and, to some extent, outdated. We thus subsequently identified the major unexplored themes and present an organized, systematic research program for a more holistic and quantifiable understanding of the interaction between social behavior and underground spaces. We end by discussing how this research program can be integrated with other disciplines, including engineering, design and health. [ABSTRACT FROM AUTHOR]

• We examine active white- (WCW) and blue-collar (BCW) workers in underground (UG) and aboveground (AG) spaces. • Job satisfaction of both WCW and BCW was mostly unaffected by being UG or AG. • Perceived confinement in UG spaces decreased with age. • Underground workspaces can be considered for both manual and office work. Modern technologies have enabled the development of high quality work environments in underground spaces (UGS).Yet, the fundamental issue of whether UGS are suitable for people intensive functions, such as office or manual work, is largely not well understood. Here, we examine whether full-time white collar (office [WCW]) and blue collar (mostly manual [BCW]) workers of UGS have different responses to critical organizational variables when compared to similar workers of aboveground spaces (AGS). Location (underground vs. aboveground) affected neither job satisfaction (overall) nor satisfaction with physical environment (overall, lighting, air quality, temperature, humidity, noise or surrounding greenery). BCW, regardless of location, reported lower satisfaction with temperature, humidity and noise but scored higher in overall job satisfaction. BCW perceived the UGS as more safe and calm; moreover, perceived confinement decreased with age, suggesting that older (or more experienced) workers are less negatively oriented towards working in UGS. These results suggest that assigning UGS to people-intensive functions (manual or office) might be a viable opportunity. [ABSTRACT FROM AUTHOR]

Objectives: We examined the combined effects of behavioural inhibition and behavioural activation, on one hand, and locus of control, on the other hand, on different categories of smoking behaviour (non-smoking, ex-smoking, occasional smoking, daily smoking)., Design: This study adopted a cross-sectional design. Participants completed questionnaires regarding demographics, smoking patterns, behavioural inhibition/behavioural activation systems and locus of control., Setting: The study was conducted across four companies from the transportation, cooling plant and education sectors in Singapore., Participants: Three hundred sixty-nine male working adults were included in the final sample., Results: Corroborating previous research, a logistic regression model examining behavioural inhibition/behavioural activation systems revealed that the fun-seeking aspect of behavioural activation was a unique predictor in distinguishing non-smokers from daily smokers (OR=1.24, p=0.012). By contrast, in a separate model examining locus of control, external locus of control was found to be a unique predictor in distinguishing non-smokers from daily smokers (OR=1.13, p<0.001). In addition, a third model combining both behavioural inhibition/behavioural activation systems and locus of control found that only external locus of control remained a significant predictor (OR=1.12, p<0.001). Further analyses revealed a mediating effect of external locus of control on the relationship between fun-seeking and smoking behaviour. That is, the increase in the odds of daily smoking due to fun-seeking was explained by external locus of control (direct pathway OR=1.20, p=0.058; indirect pathway OR=1.04, p<0.050)., Conclusions: Overall, fun-seeking through its influence on external locus of control indirectly affects daily smoking behaviour, suggesting a more complex relationship than shown in previous research., Competing Interests: Competing interests: All authors have read and agreed to the published version of the manuscript., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

To compare the prevalence of and risk factors associated with overweight or obesity between the international (body mass index [BMI] ≥25 kg/m 2 ) and Asian (BMI ≥23 kg/m 2 ) criteria in a working population in Singapore. This was a cross-sectional analysis of a cohort study of 464 employees (aged ≥21 years) conducted at 4 workplaces in Singapore. The prevalence of overweight or obesity was 47.4% and 67.0% with the international and Asian criteria, respectively. With both the criteria, higher age, male sex, Malay ethnicity (vs Chinese), lower white rice intake, and consumption of sugar-sweetened beverages were positively associated with overweight or obesity. Participants with poorer mental health and higher levels of thermal comfort in the workplace were positively associated with overweight or obesity only with the Asian criteria. The use of international criteria alone in this population could have overlooked these risk factors that are highly relevant to the Singapore context.

Underground workplaces (UWS) are increasingly being recognised as a sustainable solution to concerns regarding lack of space facing megacities. UWS can multiply available space by reducing urban sprawl thereby improving quality of life in cities. However, developing workplaces that respond to the needs and preferences of occupants will be a crucial factor in determining the success of this concept. We examine the experiences of existing full-time employees of a large underground facility in North America and analyse how these are related to company policies and other organisational factors. From in-depth interviews of 73 participants, three predominant themes emerged from the analyses: environmental effects (e.g. lack of sunlight), design (e.g. the unique working environment), and organisational factors and social dynamics (e.g. policies regarding breaks). We discuss these themes in relation with interventions that may improve employee comfort and retention and suggest that many factors are within organisational control. Practitioner Summary: Underground workplaces are a sustainable solution to lack of urban space. However, developing effective workplaces is crucial to their success. We examine the experiences of existing employees of an underground facility in North America. We suggest that most negative attitudes towards underground spaces can be mitigated through simple organisational interventions. Abbreviations: UWS: underground workplaces; IRB: institutional review board.

Objectives: We aimed to examine the prevalence of poor sleep quality and short sleep and their associated factors in a working population in Singapore., Design: This is a cross-sectional analysis., Setting: Four companies in Singapore were included in this study., Participants: Participants included 464 full-time employees (aged ≥21 years)., Measurements: Self-reported sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Self-administered questionnaires were used to collect data on sociodemographic characteristics, health behaviours, medical history, chronotype, psychosocial factors, health-related quality of life (HRQoL) and occupational factors. Clinical measurements were performed using standard tools and protocols. Multivariate logistic regression was used to examine the factors associated with poor sleep quality (PSQI global score >5) and short sleep (<7 hours/night)., Results: The mean age was 39.0 (SD: 11.4) years, and 79.5% were men. The prevalence of poor sleep quality was 42.5%, and 66.2% were short sleepers. Nearly three-fourths (71.3%) had at least one of these two conditions. Age, Malay ethnicity (vs. Chinese), chronic conditions, poorer mental health, stress at home or work and shift work were positively associated, and mental component summary of the HRQoL scale and work years in the current company were negatively associated with poor sleep quality. Age, Malay and Indian ethnicities (vs. Chinese), longer dinner-to-bed time, snacking between dinner and bed time, and poorer mental health were positively associated with short sleep., Conclusions: Poor sleep quality and short sleep were highly common in this working population in Singapore. Workplace policies should include education and intervention programmes to promote better sleep hygiene., (Copyright © 2019 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Greater adoption of wearable devices with multiple sensors may enhance personalized health monitoring, facilitate early detection of some diseases, and further scale up population health screening. However, few studies have explored the utility of data from wearable fitness trackers in cardiovascular and metabolic disease risk prediction., Objective: This study aimed to investigate the associations between a range of activity metrics derived from a wearable consumer-grade fitness tracker and major modifiable biomarkers of cardiometabolic disease in a working-age population., Methods: This was a cross-sectional study of 83 working adults. Participants wore Fitbit Charge 2 for 21 consecutive days and went through a health assessment, including fasting blood tests. The following clinical biomarkers were collected: BMI, waist circumference, waist-to-hip ratio, blood pressure, triglycerides (TGs), high-density lipoprotein (HDL) and low-density lipoprotein cholesterol, and blood glucose. We used a range of wearable-derived metrics based on steps, heart rate (HR), and energy expenditure, including measures of stability of circadian activity rhythms, sedentary time, and time spent at various intensities of physical activity. Spearman rank correlation was used for preliminary analysis. Multiple linear regression adjusted for potential confounders was used to determine the extent to which each metric of activity was associated with continuous clinical biomarkers. In addition, pairwise multiple regression was used to investigate the significance and mutual dependence of activity metrics when two or more of them had significant association with the same outcome from the previous step of the analysis., Results: The participants were predominantly middle aged (mean age 44.3 years, SD 12), Chinese (62/83, 75%), and male (64/83, 77%). Blood biomarkers of cardiometabolic disease (HDL cholesterol and TGs) were significantly associated with steps-based activity metrics independent of age, gender, ethnicity, education, and shift work, whereas body composition biomarkers (BMI, waist circumference, and waist-to-hip ratio) were significantly associated with energy expenditure-based and HR-based metrics when adjusted for the same confounders. Steps-based interdaily stability of circadian activity rhythm was strongly associated with HDL (beta=5.4 per 10% change; 95% CI 1.8 to 9.0; P=.005) and TG (beta=-27.7 per 10% change; 95% CI -48.4 to -7.0; P=.01). Average daily steps were negatively associated with TG (beta=-6.8 per 1000 steps; 95% CI -13.0 to -0.6; P=.04). The difference between average HR and resting HR was significantly associated with BMI (beta=-.5; 95% CI -1.0 to -0.1; P=.01) and waist circumference (beta=-1.3; 95% CI -2.4 to -0.2; P=.03)., Conclusions: Wearable consumer-grade fitness trackers can provide acceptably accurate and meaningful information, which might be used in the risk prediction of cardiometabolic disease. Our results showed the beneficial effects of stable daily patterns of locomotor activity for cardiometabolic health. Study findings should be further replicated with larger population studies., (©Yuri Rykov, Thuan-Quoc Thach, Gerard Dunleavy, Adam Charles Roberts, George Christopoulos, Chee-Kiong Soh, Josip Car. Originally published in JMIR mHealth and uHealth (http://mhealth.jmir.org), 31.01.2020.)

Little is known about the effect of working conditions on vitamin D status in Southeast Asia, where vitamin D deficiency is common despite the presence of sunlight all year round in most places. We examined the prevalence of vitamin D deficiency and its associated work-related factors among indoor workers using the data of 213 participants (aged ≥21 years) from a workplace cohort study in Singapore. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D (25(OH)D) concentration <50 nmol/L. Data on work-related factors, socio-demographic characteristics, and lifestyle habits were collected using standardized questionnaires. Clinical and biochemical measurements were performed using standard tools and protocols. Multivariate Poisson regression was used to examine the independent association of work-related factors with vitamin D deficiency. Mean serum 25(OH)D concentration was 59.6 nmol/L. The prevalence of vitamin D deficiency was 32.9% (95% confidence interval (CI): 26.6-39.6%). In the multivariate analysis, office workers (prevalence ratio (PR): 2.16, 95% CI: 1.12-4.16 versus control room workers), workshop workers (PR: 2.25, 95% CI: 1.05-4.81 versus control room workers), and night shift workers (PR: 1.31, 95% CI: 1.03-1.67) were at a greater risk for vitamin D deficiency. Workplace policies and wellness programs should encourage workers to take regular breaks to go outdoors for sunlight exposure and to consume adequate amounts of vitamin D-rich foods to maintain optimal vitamin D levels.

The development of underground workspaces is a strategic effort towards healthy urban growth in cities with ever-increasing land scarcity. Despite the growth in underground workspaces, there is limited information regarding the impact of this environment on workers' health. The Health Effects of Underground Workspaces (HEUW) study is a cohort study that was set up to examine the health effects of working in underground workspaces. In this paper, we describe the rationale for the study, study design, data collection, and baseline characteristics of participants. The HEUW study recruited 464 participants at baseline, of whom 424 (91.4%) were followed-up at 3 months and 334 (72.0%) at 12 months from baseline. We used standardized and validated questionnaires to collect information on socio-demographic and lifestyle characteristics, medical history, family history of chronic diseases, sleep quality, health-related quality of life, chronotype, psychological distress, occupational factors, and comfort levels with indoor environmental quality parameters. Clinical and anthropometric parameters including blood pressure, spirometry, height, weight, and waist and hip circumference were also measured. Biochemical tests of participants' blood and urine samples were conducted to measure levels of glucose, lipids, and melatonin. We also conducted objective measurements of individuals' workplace environment, assessing air quality, light intensity, temperature, thermal comfort, and bacterial and fungal counts. The findings this study will help to identify modifiable lifestyle and environmental parameters that are negatively affecting workers' health. The findings may be used to guide the development of more health-promoting workspaces that attempt to negate any potential deleterious health effects from working in underground workspaces.

With a growing need for usable land in urban areas, subterranean development has been gaining attention. While construction of large underground complexes is not a new concept, our understanding of various socio-cultural aspects of staying underground is still at a premature stage. With projected emergence of underground built environments, future populations may spend much more of their working, transit, and recreational time in underground spaces. Therefore, it is essential to understand the challenges and advantages that such environments have to improve the future welfare of users of underground spaces. The current paper discusses various psycho-social aspects of underground spaces, the impact they can have on the culture shared among the occupants, and possible solutions to overcome some of these challenges.