Modelling labour productivity of reinforcement bar using polynomial regression : a study on a tropical country's weather

For many years, the issue of environmental influence on labour productivity has received considerable attention. One of the most significant contemporary discussions in economics and construction management disciplines is about determining how weather factors influence labour productivity. While extant literature is replete with formulas and models applicable to the cold and hot climatic regions, there appears to be a paucity of useful models within the context of tropical countries such as Malaysia. With the increasing concern for climate changes and global warming, predicting how tropical weather factors may impact labour productivity is becoming an important research topic. This study developed a new model using polynomial regression based on actual data collected from a residential project in Kuala Lumpur, Malaysia. The study examined how rebar work is influenced by five weather factors: temperature, relative humidity, solar radiation, wind speed, and rainfall. The results show a 43% productivity variance due to weather factors. Further, the developed model shows how the interaction between weather factors can change the variability of productivity. The proposed model is useful for providing more accurate productivity predictions for construction management. This is useful to project planning and resolving disputes regarding progress claims

Prevalence of screen time use and its relationship with obesity, sleep quality, and parental knowledge of related guidelines: A study on children and adolescents attending Primary Healthcare Centers in the Makkah Region

BACKGROUND: Since the use of handheld electronic devises is prevalent among people of all ages, health organizations have specified appropriate screen times for the different age groups. The aim of this study was to investigate the prevalence of screen use and its association with sleep quality and obesity. MATERIALS AND METHODS: This cross-sectional study was conducted on people attending three Primary Healthcare Centers in the Makkah region between January and October 2019. The three-part questionnaire filled by parents collected data on sociodemographics, parental knowledge of guidelines, and asleep quality. Data were analyzed using STATA 14.2. For continuous variables, groups were compared using t-test; Pearson Chi-squared test or Fisher's exact test, as appropriate, was employed for categorical variables. RESULTS: A total of 450 individuals completed the questionnaire. Children 2–12 years old spent more time and used phones, tablets, and television (TV) more frequently, while those younger than 2 or older than 12 used phones and TVs more than other devices. High body mass index was associated with the daily usage of electronic devices. Fewer hours of sleep, longer time to fall sleep, and longer hours in bed were associated with the usage of all electronic devices. Furthermore, a good knowledge of the maximum time allowed for children and teenagers and content scoring system was associated with hours slept per night, and low knowledge was associated with higher frequency of using electronic devices. CONCLUSION: Children spent long periods using electronic devices, and despite knowing the guidelines, parents still allowed their children to exceed the time acceptable for the use of electronic devices, which could lead to future social problems