Appropriate use of bright light promotes a durable adaptation to night-shifts and accelerates readjustment during recovery after a period of night-shifts

Abstract

The present study examines the stability of bright light circadian readjustment during two consecutive dim light night-work periods and circadian synchronization during the recovery after a night-shift period. A sample of 10 subjects was divided into 2 groups (control group: 6 subjects; experimental group: 4 subjects). All subjects worked during 5 days, between 23:00 and 07:00 h and then went to sleep. Subjects received 2500-3000 lux between 02:00 and 05:00 h during 5 days for the control group and 3 days for the experimental group. During recovery after the night-shift periods, three cycles of bright light were administered at two different times: 12:00-15:00 h for two of six subjects from the control group and 10:00-13:00 h for all subjects (4) of the experimental group. By the fifth cycle of night-work the maximum of urinary aMT6s excretion that occurs at 05:00 h in the baseline condition was shifted to 12:00 h for the control and experimental groups (delay in hours: 7±1.6 (control); 7±1 (experimental)). This result suggests that three cycles of bright light are sufficient to induce a significant phase delay and that this delay remained stable when night-work proceeded under dim light. The phase delay of the circadian aMT6s excretion by exposure to bright light was accompanied by an improvement of the quality of day sleep and level of cognitive and psychomotor performances for control and experimental groups. No significant difference was observed in the two groups for daytime sleep and nocturnal performance. The two bright light periods used during the three days of recovery induced a complete synchronization in five of six subjects. One subject showed a partial synchronization probably because he remained at the laboratory under dim light during the day and had few family and social contacts.     

The impact of learning opportunities and decision authority on occupational health

In an investigation of 418 employees in the Norwegian Postal Service, employees with high learning opportunities and high decision authority were found to be better off on psychological functioning, health and organizational outcome variables than employees with low scores on these variables. Decision authority and learning opportunities had specific and independent impact on subjective health, psychological functioning, coping style and organizational outcome variables. There were, however, also interaction effects between demands, learning opportunities, and decision authority on subjective health. Learning opportunities and decision authority were operationalized with a questionnaire, supplemented with questions on the opportunities to learn skills beyond the present job situation. It is suggested that this is a particularly important dimension for coping with the present day rapid changes in working life, where the objective for many workers will be to broaden their repertoire and competence to increase their flexibility in the labour market.     

Development of an integrated information management model: A case of textile industry

For past two decades many organisations have tried to implement integrated information management systems for better production management based on co-ordination of information and therefore activities of different departments. Although Enterprise Resource Planning systems have been in the market for the past decade, many industries find it difficult to implement such systems due to the amount of work involved in streamlining the documentation, customisation and of high costs reported in implementation. An attempt is made through this paper to propose an integrated model, which can be easily understood by production personnel, with specific emphasis on the textile sector.     

Dynamic selection of dispatching rules for job shop scheduling

Although the academic contribution to job shop scheduling is abundant, its impact on practice has been minimal. The most preferred approach to job shop scheduling in the industry is dispatching rules. A major criticism against dispatching rules is that there is no single universal rule. The effective choice of dispatching rules depends on the scheduling criterion and existing job shop conditions. In this paper, the authors have proposed a scheduling method based on the analytic hierarchy process, that dynamically selects the most appropriate dispatching rule from several candidate rules. The selection is based on the existing job shop conditions. This method is applied to two formal job shop problems, and the results for single dispatching rules are inferior to the method proposed in this paper.     

Enabling SMEs to take full advantage of e-business

Electronic business is rapidly changing the relationships between supply chain partners. This paper looks at what is needed to allow SMEs to participate fully in supply chain integration. First, current trends in supply chain integration, electronic commerce, and Internet support are examined. Next, the goals and results of a study are presented which addressed SME needs in fast moving consumer goods supply chains. These concepts are then integrated to determine a way forward for SMEs to participate in e-business. It is found that current Virtual Markets (web-sites or on-line communities that facilitate finding a buyer or seller and track orders) address some customer - supplier relationships but need many enhancements before they can support fully integrated supply chains.     

How to make e-Procurement viable for SME suppliers

Due to their common role as suppliers, small and medium-sized enterprises (SMEs) are especially challenged by today's turbulent business conditions. In order to meet this challenge, short-term WWW-based enterprise cooperations are regarded as an appropriate way to enhance the competitive strength of SMEs. Hence, the Institute of Machine Tools and Industrial Management (IWB) operates three so-called competence networks for engineering (www.engineering-net.de), rapid prototyping (www.rp-net.de) and manufacturing (www.produktionsnetz.de) services. For the purpose of an applied research project, more than 80 participating SME suppliers have been included in these specialized virtual markets, which are based on the core competencies of the cooperating SMEs. Additionally, the platform (www.virtueller-markt.de) enables customers to configure their specific supply chains via the above-mentioned competence networks. The presented paper depicts how to establish and operate these competence networks as well as how to configure supply chains via these virtual markets.     

Multi-objectives exception management model for semiconductor back-end environment under turnkey service

On-time delivery is the need for customer satisfaction which is a critical factor in the survival of the semiconductor industry. The on-time-delivery performance of the whole semiconductor turnkey service depends on the performance of the back-end factories. Unfortunately, undesirable and inevitable production variations make it difficult to maintain and improve a factory's performance and more objectives such as cycle time, throughput rate and the due-date accuracy need to be simultaneously considered. This paper presents an exception management model in order to compromise the contradicting needs of delivery accuracy, throughput rate and cycle time. The exception model can be divided into three parts: (1) an integrated performance index is proposed to compromise multiple performance measures; (2) an AWDL (available WIP deviation level) determination model is designed to gather proper AWDLs for triggering exceptions and (3) a WIP correction action is proposed to make abnormal WIP levels back to normal levels as soon as possible. To evaluate the proposed WIP exception management model, a simulation model is constructed and experiments are then conducted. The simulation results show that the proposed model helps back-end factories to set proper exception triggering conditions, reduce uncertainty occurrences and achieve better performances on due dates.     

Modelling the tradeoff between postponement capacity and forecast accuracy

The ability to offer rapid delivery of a wide variety of customised products requires companies to maintain high levels of product inventories to quickly respond to customer demands. One alternative for reducing final product inventories while providing the required customer service level is delayed product differentiation, known as postponement. This strategy, however, can result in significant costs of increasing capacity at the postponement stage. Another alternative is to improve forecast accuracy, resulting in costs associated with more sophisticated forecasting methodologies. In this study we model the costs associated with each alternative and the resulting reductions in inventory levels, while maintaining a constant service level. We illustrate the interaction between these variables using a numerical example motivated by our work with a local manufacturer of non-durable household goods. Our findings show that large cost differences can exist between the two strategies, and that these costs play a significant role in determining the best strategy. Also, the value of the product (through holding cost) sets a limit on the benefit that can be realised by either strategy. These results have important managerial implications that should be considered when making the postponement decision.     

When outsourcing fragments: customer creativity and technological transmutations

One of the most fundamental decisions made in firms is about what functions or activities the firm should perform within its own hierarchy, and which of these it should rely on the market to perform. Outsourcing is ‘an agreement in which one company contracts out a part of their existing internal activity to another company’. However, this article contends that outsourcing has changed, and is changing in ways that make the application of neat, legal and technically correct definitions hard to use, and even harder to apply in strategy. Under the new outsourcing paradigm, technology is not a passive ‘substance’, rather it is an active ‘force’. We aim to look at the ways in which technologies are re-shaped and transmuted by consumers. Through this analysis, we add the consumer activity to the conventional definition of outsourcing. We focus on one of the most highly anticipated and influential new products of 2007 – the Apple iPhone.     

Green supply chain management practices in India: an empirical study

This paper presents an empirical study of green supply chain management (GSCM) practices in the Micro, small and medium enterprises (MSMEs) in India. Although the research in the area of GSCM has grown in recent times, the literature has yet to furnish an accepted explanation for why green practices are to be manifested in supply chain management given external and internal pressures. These MSMEs have been involved in such green supply chain practices only to the extent of their participation as suppliers, distributors and in other capacities as business partners. This study confirms and validates that Indian MSMEs face significant pressures from external stakeholders to adopt GSCM practices. Among internal pressures, on-the-job training forces MSMEs in India to adopt GSCM practices. It has been also established that external pressures and adoption of GSCM are fully mediated by internal pressures.