Childhood Trajectories of Hyperactivity/Inattention Symptoms and Diurnal Cortisol in Middle Adolescence: Results from a UK Birth Cohort

Objective Children with attention-deficit/hyperactivity disorder (ADHD) show hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Whether the association between hyperactivity/inattention symptoms with HPA axis dysfunction holds in the general child population too is not clear. Method We assessed associations between longitudinal trajectories of hyperactivity/inattention symptoms during ages 4 to 13 years and basal cortisol profiles at age 15 in a British general population cohort. Results Adolescents with persistently high levels of hyperactivity/inattention symptoms since childhood showed lower total morning cortisol and a smaller diurnal decline, even after adjusting for confounders. No associations were found between any of the symptom trajectories and cortisol awakening response, diurnal slope or daily output of cortisol. Conclusion This study provides evidence for hypocortisolism among adolescents with chronic hyperactivity/inattention symptoms in the general population.

Prediction of the Potential Daily Output of a Shearer-Loader

Economic analysis allows for determining the required daily output under certain natural and mining conditions based on the costs of the production process in a particular mine infrastructure. Therefore, there is a need to determine the potential daily output of a longwall using the technical equipment at the disposal of the mine. In the case of mines, when exploiting a few longwalls simultaneously in the conditions of bumping hazards, it is indispensable to ensure safety. Due to a necessity of keeping a safe distance among the longwall fronts, when planning their exploitation, developing a prediction of the longwalls in advance during the planning period is needed. To predict the daily production from a longwall and daily advance of the longwall in the analyzed period, it is necessary to know the current operating time of machines and the capacity of the shearer under given conditions. The current working time of machines results from the available time and the degree of its utilization, which is determined by the sum of unplanned breaks in the production process. The shearer productivity is determined by its haulage speed. Both factors mentioned above are random. Hence, a calculation module has been developed, whose task is to estimate the distribution parameters of these indicators based on empirical data. The algorithm for estimating the parameters of one of the distributions: normal, steady or gamma and its special case of the exponential distribution and Poisson for the obtained input empirical data, constituting a sample from the population, is proposed. The input data are a sequence of numbers obtained from the measurement of the current operating time of machines. These data can be obtained from the longwall shearer memory card, on which its operating parameters are recorded in each longwall. On this basis, it is possible to generate random values of both parameters for individual days of operation. The possibility of determining the haulage speed, based on the longwall shearer’s characteristics obtained from the computer simulation of the mining process, is also discussed. The simulation of the mining process is carried out using the GeneSiSv.3.1 software, developed for designing a picks layout on the drum. The characteristics of the shearer production potential also take into account the capacity of loading the cutting drum. It results from the presented characteristics that, when mining coal with a compressive strength of 27 MPa, the haulage speed is limited by the loading capacity of the cutting drum and, with greater cuttability, by the power of the electric motor driving the drum. The paper presents algorithms describing the procedure of generating random values necessary for determining the longwall production potential and the daily advance during the assumed period. The subject matter presented in the paper is part of a bigger project which concerns planning of a mine operation and developing a few longwalls in the conditions of bumping hazards.

Assessment of the effective working time on the mining output of the mechanized longwall (coal seam 11) in Ha Lam coal mine

The mechanizetion of Ha Lam coal seam 11 was designed with mining output of 600.000 tous per year. In fact, due to the negative impact of geological conditions as well as the irrationality of the initial production organization, the mining output of the longwall is not reached according to the designed capacity. The paper proposes a method to determine the effective working time of the actual longwall based on each component stage. For specific conditions at coal seam 11 in Ha Lam coal mine. The mean flow rate of the mining stream is considered as a directional factor of the linear function describing the relation between the daily output and the effective mining in the longwall face. This relation is also considered as motivation in particular for supervisory personnel, as it shows advantages resulting from elongation of this time, as well as it shows possible losses of the daily output in a case when the effective working time is given longwall face was shortened.

Emotional Status and Productivity: Evidence from the Special Economic Zone in Laos

Employee productivity is a well-studied area, which has been explained in various dimensions. However, there is insufficient research on how workers’ on-job emotional status relates to productivity. This study examined the relationship between workers’ emotional states and productivity by assessing on-job emotionality recorded using a specially designed wearable biometric device. The experiment was conducted at KP Beau Lao Co. Ltd., a Japanese plastic toys and cosmetic products company in Savannakhet province in Southwestern Laos. Participants were 15 plastic toy painters. Mental status, daily output, and other issues were recorded for three consecutive working days. Using random effects panel regression models, we examined how productivity, operationalized as the log of daily output, was related to workers’ emotional states, including the amount of time workers reported being happy, angry, relaxed, and sad. We controlled for conversation time, heart rate, and other demographic features. The results revealed that happiness, and no other emotional state, was significantly and positively related to productivity. Such findings suggested that workers’ emotional states must be addressed as part of an organization’s operational strategy to ensure higher productivity.

Construction and demolition waste applications and maximum daily output in Spanish recycling plants

The pursuit of construction sustainability has driven the use of partially or wholly waste-based eco-materials. New applications are being sought for recycled aggregate (RA) to further the use of this material and ensure the survival of the construction and demolition waste (C&DW) industry. RA, currently used in the construction of pavements, fills and embankments and only incipiently to manufacture structural or non-structural concrete, is a mere 8.99% of the total aggregate extracted in EU countries where RA is produced. Against this backdrop, the utility of this study lies in the overview afforded of RA typology, the application of the product in bound or unbound materials, the pursuit of new applications, structural or otherwise, and the assessment of daily maximum output by C&DW recycling facilities in Spain. The findings show that irrespective of its origin, RA most commonly adopts the form of wet mix macadam, gravel or sand used primarily in unbound applications with only dubious quality standards. Plant managers contend that RA from clean waste can feasibly be used in bound applications that require higher-performance materials. Maximum daily output varies widely, with capacity under 200 t d-1 in 30% of the plants. One of the conclusions drawn is that the current business model is in need of revision, with an emphasis on aggregate quality control (certification) and the adoption of technology for separating out impurities, pollutants and undesirable materials to improve the quality of RA.

The Effect of Pollution on Worker Productivity: Evidence from Call Center Workers in China

We investigate the effect of pollution on worker productivity in the service sector by focusing on two call centers in China. Using precise measures of each worker’s daily output linked to daily measures of pollution and meteorology, we find that higher levels of air pollution decrease worker productivity. These results manifest themselves at levels of pollution commonly found in large cities throughout the developing and developed world. (JEL J24, L84, O13, P23, P28, Q51, Q53)