Working Time Schedules Research Articles

Robust Energy Management for a Corporate Energy System With Shift-Working V2G

The penetration of plug-in electric vehicles (PEVs) has greatly increased over the past few years. By using vehicle-to-grid (V2G) technology, PEVs can be used as “mobile batteries” in a microgrid. Here, we aim to coordinate the V2G dispatch with traditional energy management in a corporate energy system (CES). To do so, a two-stage robust optimization (RO) model is built with respect to uncertainties in the CES, e.g., photovoltaic (PV) power. Particularly, relationships between the working time schedule and PEVs are investigated and analyzed for the first time, and a novel PEV aggregator model, i.e., shift-working V2G, is presented. The shift-working V2G model provides beneficial characteristics, like weakened randomness and stable storage capacity. A quantitative method to evaluate the V2G capacity is then presented. An analytical solution methodology is also proposed, which can equivalently convert the robust “min-max-min” model to a single-level mixed-integer linear programming (MILP) model. Case studies are conducted for an iron and steel company in Shanghai, China, with almost 40 000 PEVs. The results show that V2G integration can significantly improve the load-tracking ability of CES and help reduce the energy cost, although the V2G cost is considered. The computational efficiency is also improved compared with the existing methods. Note to Practitioners-This article is motivated by the problem of using the battery storage capacities of plug-in electric vehicles (PEVs) in a corporate energy system (CES) such as an iron and steel plant, aiming at minimizing the energy cost. In existing studies, behaviors of PEVs (e.g., arriving or leaving time) have usually been elusive since they are directly decided by drivers, and thus, it is difficult to determine how much storage capacity PEVs can provide. However, in a CES where a shift-work regulation is implemented, employees should arrive or leave punctually during each shift, and the same is true of their PEVs. Based on this fact, PEVs within one shift could show weakened randomness and stable storage capacities. In this article, the influences of the shift-work regulation on the PEVs are fully analyzed, and the shift-working V2G provides an easy way to integrate PEVs into the CES. In practice, the shift-working V2G model can be applied to any energy system that also implements a shift-work regulation, such as a fire station.

Work-life balance among athletes

The application of the work-life balance conception has become increasingly popular in recent years. This conception draws not only from legal solutions, but from psychological sciences and those related to human resources management. In the field of labour law, the instruments used may be, inter alia, rights related to parenthood (maternity, paternity, parental and extended parental leave), the use of fixed-term contracts or part-time employment, the use of individual working time schedules, the use of task-based schedules, equivalent or intermittent working time, telework regulations, variable work start and end times. However, employment in professional sports is atypical. The very essence of providing sports work is different from the essence of performing both office and industrial work. It consists in the provision of a special type of work of a multiple nature aimed at maximising the performance of athletes, carried out for profit. The athlete’s ability to achieve success results from the effect of actions taken as part of the employment relationship with the club as well as from leisure activities. Such activities include preparing appropriate meals, keeping a balanced diet, refraining from an unhealthy lifestyle and from the use of unauthorised substances, not using drugs that could be considered doping, taking care of proper regeneration and rest, and refraining from betting on matches in the practiced sport discipline. Herein, firstly, the characteristics of sports work was presented and, secondly, the possibilities of using work-life balance tools in shaping everyday sports work were analysed. The paper analyses the phenomenon of blurring personal and professional lives among athletes. The main conclusion of the paper is the inability to effectively guarantee a work-life balance among athletes, and that athletes can effectively use legal tools of WLB only if they simultaneously perform services or work elsewhere. The paper uses a dogmatic and legal method (analysis of the literature on the subject, analysis of normative acts) and the results of research carried out by the author, i.e. a survey addressed at professional athletes

Optimization of Cost and Time of Repair and Rounding of Roads With Way Pavement Design Manual Method 2013

Smoothness, safety, and comfort of traffic depend on road pavement conditions. If the width of the road is narrow, damaged, hollow, the traffic will disrupted; the travel time will increase, fuel consumption increases, the risk of damage to high vehicles and so on, if there is no immediate improvement in the form of an increase, the damage will increase. To deal with this problem, it is necessary to research and plan road improvements with widening, an increase in existing pavements with overlays, the need for cost and time of implementation. The Mojokerto - Ploso road segment is an alternative route connecting the cities of Mojokerto - Jombang, and Lamongan. Based on the status of the road is the provincial road, and based on the function is the Collector’s road. Furthermore, for the planning of improvement and widening required subgrade CBR data, for overlay planning, a Test Pit data is needed to determine the existing pavement structure and traffic data. In determining the road widening plan, the 2015 revised Road Pavement Design Manual (MDP) method for overlaying was used with the Planning Guidelines for Pt-T-01-2002-B Bending Pavement Thickness and calculating the Budget using Work Unit Price Analysis (AHSP ) 2013, creating a Schedule of Work (Time Schedule), as well as calculating the critical path to find out the critical path in carrying out the work. To planning data analysis is needed - traffic data, land investigation, layer thickness calculation on widening, overlay layer thickness, cost requirements, execution time and critical track path. From the calculation results, the road widening obtained AC = 5 cm pavement arrangement, ATB = 14 cm, CTB = 30 cm, Class B Aggregate = 20 cm, the optional load support layer = 85 cm, using geogrid as the selected urine separator with subgrade, in the old pavement repair (overlay) with an overlay, the AC = 5 cm arrangement, ATB = 14 cm, at a cost of Rp. 19,200,000,000.00 (Nineteen billion two hundred million rupiahs) with a 20-year plan life, as well as a 6-month implementation time.

Association between irregular menstrual cycles and occupational characteristics among female workers in Korea

ObjectiveTo examine the association between irregular menstrual cycles and occupational characteristics among Korean female workers. Study designWe analyzed data on paid female workers from the Korea National Health and Nutrition Examination Survey (KNHANES) V (2010–2012). Main outcome measuresWe evaluated the possible associations between irregular menstrual cycles and work variables (occupational classification, working hours, and shift work) using univariate and multivariate logistic regression analyses. Weighted prevalence was calculated according to each work variable to approximate the Korean population. ResultsIrregular menstrual cycles were the most common in women in the ‘pink collar’ group (16.61%). The frequency of irregular menstrual cycles was 2-fold higher in women working >60 h per week (25.64%) than in those working 20–60 h per week (11.09%). Irregular menstrual cycles were more prevalent in shift workers (15.85%) than in non-shift workers (11.06%). A significantly high risk of irregular menstrual cycles was found for pink-collar occupations (adjusted odds ratio [OR] = 1.687, 95% confidence interval [CI] = 1.044–2.710, reference: white-collar occupation group) and in women with long working hours (adjusted OR = 2.139, 95% CI = 1.243–3.559, reference: 20–60 working hours group) and shift work (adjusted OR = 1.487, 95% CI = 1.028–2.118, reference: fixed working schedule group). ConclusionsOur study showed associations between irregular menstrual cycles and occupational characteristics of female workers. Long working hours, shift work, and pink-collar occupations are positively associated with irregular menstrual cycles. Therefore, working hours and shift schedules for female workers should be structured considering these factors. Further research is needed to determine the optimal working time and shift schedules for female workers.

Insomnia as a Partial Mediator of the Relationship Between Personality and Future Symptoms of Anxiety and Depression Among Nurses.

Background: This study investigates insomnia as a partial mediator in the relationship between personality and symptoms of anxiety and depression.Methods: The study is based on partly longitudinal data from the ongoing cohort study “Survey of Shift work, Sleep, and Health” (SUSSH) among Norwegian nurses, a survey examining the work situation and health status of Norwegian nurses measured with annual questionnaires. The present study uses data collected in 2012 (Wave 4), 2013 (Wave 5), and 2014 (Wave 6). The final sample at Wave 6 consisted of 2002 participants, of which 91% were females. The questionnaires included items measuring, among others, demographic variables, work time schedule, insomnia (Bergen Insomnia Scale), personality (Mini-IPIP) and anxiety and depression (Hospital Anxiety and Depression Scale).Results: Extraversion and conscientiousness had no significant direct or indirect association with insomnia, anxiety or depression. Neuroticism and insomnia had direct associations to future symptoms of anxiety and depression. Insomnia was also a significant partial mediator of the relationship between both neuroticism and anxiety, and neuroticism and depression, meaning that neuroticism had an indirect relation to symptoms of anxiety and depression through insomnia. When adjusting for previous symptoms of anxiety and depression at Wave 5, insomnia was no longer a significant mediator between neuroticism and anxiety, and only marginally mediated the relationship between neuroticism and depression.Conclusion: The results showed that insomnia may act as a mediator between neuroticism and symptoms of anxiety and depression, but the indirect relationship between neuroticism and anxiety and depression through insomnia is considerably weaker than the direct association. Hence, the mediating effect of insomnia should be interpreted with caution. The sample mainly consisted of female nurses, and the generalizability of the findings to male dominated occupations is limited. Findings from the present study highlight the importance of an integrated approach and strengthen the understanding of how personality and psychopathology are connected.

A review on human resources management (HRM) theories and effective human resource management models

Human Resource Management (HRM) has become more important to strategic management, particularly as a result of its role in providing competitive benefit, advantage and the rush to competitiveness. Human Resources are seen as the available talents of people to an organization as potential contributors to fulfill the organization's mission, v ision, strategy and goals. Drastic changes occurred when machines and industry manufacturing methods were introduced in early 1900. Since machines and devices were introduced for manufacturing industries, laborers and workers expected very high output minimizing the labour cost. When a machine or device required several number of workers to operate its different functions, supervisory and control procedures were necessary and must for managing the workers owing to the factors like how different duties are assigned and allocated among workers, and to maintain worker relationships, communication, and job divisions. Factory authorities started to frame and design rules, regulations, work time schedule, job assignment methods and procedures, remuneration pay structures. They further designed proper and appropriate plans for getting a maximum output of the labour through job specialization. This trend was mostly influenced for the development of the theory called Scientific Management. Taylor (1856–1915) is called as the father of scientific management, who introduced several management principles and rules for organizations. This is one kind of first theoretical approaches for HRM during that period. The second theoretical approach of HRM is the human relation school developed by Mayo (1880–1949) and Roethlisberger through their Hawthorne research studies. The above theories are not classified as HRM theories, but they have a direct influence for the advancement and development of HRM theories. This review paper discusses on Human Resources Management (HRM) theories and effective human resource management models, HRM definition, nature of HRM, scope of HRM, role of HRM, importance of HRM, models and theories of HRM. Besides, HRM theories like universalistic theory, contingency theory, configurationally theory are discussed.

Analysis of telecommuting behavior and impacts on travel demand and the environment

The discussion of whether, and to what extent, telecommuting can curb congestion in urban areas has spanned more than three decades. This study develops an integrated framework to provide the empirical evidence of the potential impacts of home-based telecommuting on travel behavior, network congestion, and air quality. In the first step, we estimate a telecommuting adoption model using a zero-inflated hierarchical ordered probit model to determine the factors associated with workers’ propensity to adopt telecommuting. Second, we implement the estimated model in the POLARIS activity-based framework to simulate the potential changes in workers’ activity-travel patterns and network congestion. Third, the MOVES mobile source emission simulator and Autonomie vehicle energy simulator are used to estimate the potential changes in vehicular emissions and fuel use in the network as a result of this policy. Different policy adoption scenarios are then tested in the proposed integrated platform. We found that compared to the current baseline situation where almost 12% of workers in Chicago region have flexible working time schedule, in the case when 50% of workers have flexible working time, telecommuting can reduce total daily vehicle miles traveled (VMT) and vehicle hours traveled (VHT) up to 0.69% and 2.09%, respectively. Considering the same comparison settings, this policy has the potential to reduce greenhouse gas and particulate matter emissions by up to 0.71% and 1.14%, respectively. In summary, our results endorse the fact that telecommuting policy has the potential to reduce network congestion and vehicular emissions specifically during rush hours.

Spreadsheet as a means to support working time scheduling - data integrity in a spreadsheet tool

Spreadsheet as a means to support working time scheduling - data integrity in a spreadsheet tool

Low back pain in farmers: The association with agricultural work management, disability, and quality of life in Korean farmers

AbstractThis study aimed to identify the associations among low back pain (LBP), LBP‐related disability, agricultural working condition management, and quality of life (QOL) in Korean farmers. Demographic information, agricultural work management, and outcomes of LBP were obtained by standardized questionnaires (Oswestry Disability Index [ODI] for disability and European Quality of Life‐5 Dimensions‐3‐Level version [EQ‐5D‐3L] for QOL). Presence of LBP was determined if the LBP had lasted longer than 1 week or had been more frequent than once a month, and presence of LBP‐related disability was determined if the ODI score was more than 12. Poor health checkups (OR [odds ratio] = 1.70–86, p < .05), were positively associated with LBP, and working at dawn (OR = 1.85–1.96, p < .05), was positively associated with LBP‐related disability after adjusting related demographic factors. EQ‐5D‐3L indexes were significantly lower in participants with LBP (0.83 ± 0.17 vs. 0.92 ± 0.06, p < .001) and disability (0.81 ± 0.18 vs. 0.93 ± 0.05, p < .001). This study showed that the presence of LBP was related to poor health checkups and that LBP‐related disability was related to a poor working time schedule. These results indicate poor QOL and suggest the need for coping strategies such as regular health checkups and a proper working time schedule.

Screening for Methicillin-resistant Staphylococcus aureus in a residence home for elderly in Germany

BackgroundSince many hospitals report high MRSA colonization rates among elderly patients, and because it has been shown that S. aureus colonization increases with advancing age, there are concerns about the introduction of MRSA into nursing homes by MRSA positive patients discharged from hospital. So far, admission screening and subsequent longitudinal screening in residence homes or screening at time of hospital discharge is not established on a regular base. On the other hand, MRSA is acquired frequently during hospital stay. Therefore, the MRSA status of residents remains unclear at the time of re-admission to the residence home. This study was conducted to evaluate the rate of nasal MRSA carriage among residents and nursing staffs of 2 nursing homes for the elderly, the potential acquisition of MRSA during a hospital stay and the feasibility to perform direct screening tests in nursing homes for elderly.MethodsIn a study period of 5 months, possibility of active PCR-based screening for MRSA has been tested within 2 residence homes for the elderly, with the obligation to avoid inconvenience to the daily working time and working schedule. Residents and staff members were included in the study and positive test results were confirmed with MRSA culture.ResultsFeasibility of active on site screening in a residence home for the elderly using a rapid PCR method has been confirmed. 154 of 156 residents participated on baseline testing for all current and new admitted residents. In 9 participating residents with former unknown status, nasal carriage with MRSA was confirmed (5.8%). Among 32 documented and eligible movements between the nursing home and the hospital, MRSA could be confirmed after return to the residence home in 2 cases (6.3%). MRSA could also be detected in 1 of 14 participating nursing staff (7.1%).ConclusionPrevalence of MRSA was in a range that has been observed for nursing homes in Germany in previous studies. Residents can acquire MRSA during a hospital stay so that further spread after re-admission into the nursing home cannot be excluded. This study shows that easy to perform direct screening tests in outpatient facilities for nursing of the elderly are promising tools as part of potential new strategies for transmission and infection control in such facilities. Additional studies are needed to investigate if screening followed by interventional hygiene measures can reduce MRSA transmission and infection in such facilities.

The impact of family-friendly policies in Spain and their use throughout the business cycle

The aim of this paper is to evaluate the family-friendly law (Act 39/99) approved in Spain in 1999, which grants parents the right to reduce work time schedule for childcare issues. We find an increase of work time reduction by around 18 %. Second, we find that employers restrict indefinite contracts to potential users of the law to limit its use. Finally, we find that in the recent downturn the use of the law decreased by around 13 % compared to the previous economic upturn. JEL codes: C23, J16, J18, J62

The Effects of Women′s Labour Force Participation and Work-Family Reconciliation Support on Fertility

This study analyzes the effects of women`s labour force participation and work-family reconciliation support on life-cycle fertility in Korea. The analysis is based on the longitudinal data from Korean Labour and Income Panel Study (KLIPS), which include the available information on life-cycle fertility and employment history. Employing a dynamic model of fertility, we estimated the life-cycle fertility of all the 15-49 years old women considered in this study by using a duration model. The major results of this study were as follows: First, women`s labour force participation had a negative effect on the first birth, second birth, and all births (transition to births starting at different parities). Women`s employment tended to lengthen the interval between births. Second, the availability of maternal leave had a positive effect on the first birth and all births for working women. Providing maternal leave to working women decreased the opportunity cost of childbearing and in turn, reduced the interbirth interval of women. However, the availability of parental leave had no significant effect on the births of working women. Third, the financial support for childcare had a positive effect on the first birth and all births. The economic support for childcare led to the reduction in the interbirth interval of women by increasing the probability of births. The use of a childcare center for the first child, which substitutes for the time that women needed to take care of their children, classified as time-intensive consumption goods, did not have any effect on the second birth. Fourth, the part-time employment of women had a positive effect on the second birth. A flexible working time schedule tended to decrease the interval between the first and the second births.

The Demographic Variables and Emotional Intelligence as Correlates of Work Values: A Cross-Cultural Examination towards Organizational Change

This research paper is a cross-cultural study of demographic variables and their role on emotional intelligence and work values among 437 purposively selected call center representatives (CSRs) from the Middle East, Iran, Pakistan, Russia, India, and the Philippines. The paper aims to establish a baseline literature on the link between demographic variables (such as gender, civil status, work time schedule, and nationality) on emotional intelligence and work values that leads to the appropriate conceptualization of organizational change programs. The descriptive, comparative-correlational methods were employed as this paper also threshes out whether CSRs differ on emotional intelligence and work values based on demographic characteristics. The researchers utilized three instruments such as Demographic Profile Sheet, Emotional Competence Inventory, and Work Values Inventory. The general findings confirm that there is a significant relationship between emotional intelligence (particularly on the clusters of self- management, social awareness and relationship management) and work values (specifically in the areas of management, achievement, supervisory relations, way of life, and independence). In line with the results, the organizational change programs with emphasis on diversity management have been introduced to set future directions for organizations in call center organizations involved in the study.

The Impact of Family Friendly Policies in Spain and Their Use Throughout the Business Cycle

The aim of this paper is to evaluate various aspects of a family friendly law (Act 39/99) approved in Spain in 1999, which grants parents the right to reduce their work-time schedule for childcare issues. Moreover, those who resort to that law enjoy higher protection against dismissal than other workers, which may encourage workers to use the law as a form of job protection, particularly in recession periods. We first test the direct impact of the law, i.e. whether its passing increased the use of work-time reduction for childcare issues. We find that the use of such measures did indeed increase by around 18%. Second, we test whether the passing of the law led to strategic behavior from employers, in the sense of restricting indefinite contracts to potential users of the law to limit the use of work-time reduction. We find that this is indeed the case. Finally, we test whether this law was resorted to more or less in the recent downturn than in the previous economic upturn. We find that its use decreased by around 13% in the recent downturn, which is not consistent with the view that workers would use the law more intensively during recessions for job protection reasons.

Flexible Working and Couples' Coordination of Time Schedules

Using previously unexploited data on time scheduling in the employment and household contexts, we investigate the effect of flexible working on couples' coordination of their daily work time schedules in the UK. We consider three distinct dimensions of flexible working: flexibility of daily start and finish times (flexitime), flexibility of work times over the year (annualised hours), and generalised control of working hours. We find that in couples with flexitime there is greater spouse synchronization in daily working times by nearly one hour. The effect is driven by couples with dependent children. However, we find the effect in couples with children of any age (under 16), suggesting it does not stem from the childcare requirements of young children. Robustness checks indicate that flexitime is not endogenous, suggesting that an expansion of flexitime would increase couples' work time coordination. There is less evidence that broader control over working hours increases daily synchronous working time and no evidence that annualised hours increase synchronous time on a daily basis. The weaker relationships with daily synchronous time for these two flexibility measures are consistent with their broader scope (control over amount of hours as well as timing) and longer time span.

Families, meals and synchronicity: eating together in British dual earner families

Based on a sample of British dual earner families with young children drawn from the National Diet and Nutrition Survey, the paper examines their food practices, in particular the conditions under which families are able to eat together or not during the working week. The concept of synchronicity is drawn upon to shed light on whether meals and meal times are coordinated in family life and the facilitators and constraints upon coordination. The paper suggests that whether families eat together is not only influenced by parents' work time schedules but also children's timetables relating to their age and bodily tempos, their childcare regimes, their extra-curricular activities and the problem of coordinating different food preferences and tastes.

Organização do Trabalho e Comprometimento da Saúde: Um Estudo em Caminhoneiros

The study discusses some health problems or health risks - obesity, high blood pressure, high cholesterol levels, diabetes, postural alterations, for instance - found in the work of truck drivers, considering aspects related to work organization. Data collection was carried out during the development of a health program focused on the health of truck drivers, sponsored by the Concessionary of the Anhanguera-Bandeirantes System - AutoBAn (a company of the CCR Group), along the Anhanguera and the Bandeirantes highways in the state of Sao Paulo. A closed questionnaire was used for the survey containing questions directed to the life style and work style of truck drivers, and to the way they interfered in their quality of life and their health. Blood pressure of the truckers was measured and other health parameters were analyzed, such as smoking, sedentarism, overweight and obesity, and hereditary factors for diseases. The results of the study show that to 53,39% of the truck drivers interviewed their work activity interferes in their physical health, whereas 43,89% indicated an impact on their mental health. There is also an evident influence of working time and irregular schedules on physical and psychological overcharge, and their mental and physical symptoms, such as relationship problems, loneliness, sleepiness, irritability, fatigue, and diminished reflex that can lead not only to chronic diseases but also acute diseases, among which, polytraumatisms caused by accidents in the highways. Keywords: Truck drivers. Unusual schedule. Work organization. Worker illness.

Conflict Between Work and Family Roles and Satisfaction among Nurses in Different Shift Systems in Croatia: a Questionnaire Survey

The objective of this study was to examine the perception of conflict between work and family roles and job, family, and life satisfaction among nurses in Croatia. One hundred and twenty-nine nurses (married mothers) working in hospitals in Zadar, Šibenik, and Split were divided in four groups according to their worktime schedule. The participants completed a survey, which included a set of sociodemographic-type questions, questions about the level and allocation of family responsibilities between spouses, and scales measuring the perceived negative effects of worktime, psychological demands of the work, work-family conflict, and semantic differential scales for measuring the affective and cognitive-evaluative component of job, family, and life satisfaction. This was the first study in Croatia to deal with work-family conflict among nurses or workers with different shift systems.The results of this study indicate that nurses working morning shifts only experienced less conflict between work and family than other groups of nurses, who worked the morning, afternoon, and the night shift. The cognitive-evaluative component of job satisfaction was the highest among morning shift nurses and the lowest in nurses who worked 12-hour shifts, while the affective component of life satisfaction was the lowest in nurses working irregular and backward rotated shifts. These results confirm that shiftwork makes the work-family role conflict even worse. They also support the view that the type of shift rotation matters.

CHRONOTYPE, SLEEP LOSS, AND DIURNAL PATTERN OF SALIVARY CORTISOL IN A SIMULATED DAYLONG DRIVING

The study focused on chronotype-related differences in subjective load assessment, sleepiness, and salivary cortisol pattern in subjects performing daylong simulated driving. Individual differences in work stress appraisal and psychobiological cost of prolonged load seem to be of importance in view of expanding compressed working time schedules. Twenty-one healthy, male volunteers (mean ± SD: 27.9 ± 4.9 yrs) were required to stay in semiconstant routine conditions. They performed four sessions (each lasting ∼2.5 h) of simulated driving, i.e., completed chosen tasks from computer driving games. Saliva samples were collected after each driving session, i.e., at 10:00–11:00, 14:00–15:00, 18:00–19:00, and 22:00–23:00 h as well as 10–30 min after waking (between 05:00 and 06:00 h) and at bedtime (after 00:00 h). Two subgroups of subjects were distinguished on the basis of the Chronotype Questionnaire: morning (M)- and evening (E)-oriented types. Subjective data on sleep need, sleeping time preferences, sleeping problems, and the details of the preceding night were investigated by questionnaire. Subjective measures of task load (NASA Task Load Index [NASA-TLX]), activation (Thayer's Activation-Deactivation Adjective Check List [AD ACL]), and sleepiness (Karolinska Sleepiness Scale [KSS]) were applied at times of saliva samples collection. M- and E-oriented types differed significantly as to their ideal sleep length (6 h 54 min ± 44 versus 8 h 13 min ± 50 min), preferred sleep timing (midpoint at 03:19 versus 04:26), and sleep index, i.e., ‘real-to-ideal’ sleep ratio, before the experimental day (0.88 versus 0.67). Sleep deficit proved to be integrated with eveningness. M and E types exhibited similar diurnal profiles of energy, tiredness, tension, and calmness assessed by AD ACL, but E types estimated higher their workload (NASA-TLX) and sleepiness (KSS). M types exhibited a trend of higher mean cortisol levels than E types (F = 4.192, p < .056) and distinct diurnal variation (F = 2.950, p < .019), whereas E types showed a flattened diurnal curve. Cortisol values did not correlate with subjective assessments of workload, arousal, or sleepiness at any time-of-day. Diurnal cortisol pattern parameters (i.e., morning level, mean level, and range of diurnal changes) showed significant positive correlations with sleep length before the experiment (r = .48, .54, and .53, respectively) and with sleep index (r = .63, .64, and .56, respectively). The conclusions of this study are: (i) E-oriented types showed lower salivary cortisol levels and a flattened diurnal curve in comparison with M types; (ii) sleep loss was associated with lower morning cortisol and mean diurnal level, whereas higher cortisol levels were observed in rested individuals. In the context of stress theory, it may be hypothesized that rested subjects perceived the driving task as a challenge, whereas those with reduced sleep were not challenged, but bored/exhausted with the experimental situation. (Author correspondence: mmoginsk@cyf-kr.edu.pl)

RESTRUCTURING LABOUR TIME: IMPLEMENTING ALTERNATIVE WORKING-TIME ARRANGEMENTS ON SOUTH AFRICAN MINES, 1991–2004

Two case studies suggest the restructuring of labour time in South African mining is indissolubly linked with work reorganisation. This results in organisational complexity by virtue of a plethora of production and social issues requiring attention, and alluded to in this article. Two primary forms of temporal restructuring are identified: the first option, continuous operations, is preferred by the industry and marks the lengthening and absolute extension of aggregate social labour time. It extends labour time to its maximum temporal limit, disrupting established patterns of social life. This option represents a retrogressive social development and is resisted by organised labour. The second option, a five-day working week, is preferred by labour organisations and marks the shortening and relative intensification of labour time expenditure. It results in the rhythms of working-time remaining more regular, maintaining established patterns of social life. This option represents a progressive social development, yet is resisted by mining capital. When changing working-time arrangements, the adoption of mining capital's preference results in the social impact of continuous working-time schedules coming to the fore. The adoption of organised labour's preference results in issues of control over the labour process coming to the fore when reducing working hours.