In this study, the relationship between age, sleep, and health in a group of shiftworking nurses was investigated. The study forms part of a larger study into the health and well-being of shiftworking nurses and midwives in England and Wales (Department of Health, 1993). First the importance of the relation between age and sleep was considered. Next, the impact of two important moderating variables, shiftwork and gender (roles), was examined. The nurses worked two very different shift systems: permanent night shifts or rotating shifts. The gender distribution in the sample was very skewed, which resulted in the inclusion of gender roles as variables. Having established the relative importance of the three variables, the next step was to investigate effects of the relation between the variables. Reduced alertness was the most important acute effect considered. Health and well-being complaints were considered as the main chronic effects. It was concluded that age has an important impact on sleep. The results however contradicted the dominant view in the literature that with age sleep always deteriorates. It was important to distinguish between sleep quantity and sleep quality. Both shiftwork and gender (roles) moderated the negative impact of age. Alertness was affected in a counterintuitive manner: older nurses reported feeling more alert compared to younger nurses. With regard to health and well-being, again results were surprising: health and well-being appeared to be more affected by reported sleep quality than by sleep duration. The results from this study were more varied and less linear than could have been assumed on the basis of the literature. It is argued that research should beware of unjust generalisations and move away from simple dichotomies and allow for a more varied and colourful picture.

A novel approach for estimating alertness levels from speech and tagging them with a reliability component has been developed. The Fatigue Quotient and Believability are both derived from the time series analysis of the speech signal in the communication between the operator and dispatch. Operator attention is the most important human factor element for safe transportation operations. In addition to substance abuse, illness and intoxication fatigue is a major contributing factor to the decrease of attention. The goal of this study was to develop a means to detect and estimate fatigue levels of railroad operating personnel during on-duty hours. This goal continues to gain importance with new efforts from the government to expand rail transportation operations as a tool for high speed mass transportation in urban areas. Previous research has shown that sleeping disorders, reduced hours of rest and disrupted circadian rhythms lead to significantly increased fatigue levels which manifest themselves in alterations of speech patterns as compared to alert states of mind. In this study vocal indicators of fatigue are extracted from the speech signal and Fuzzy Logic is used to generate an estimate of the cognitive state of the train conductor. The output is tagged with a believability metric based on its behavior with respect to previous outputs and a fully alert state. Communication between the conductor and dispatch over radio provides an unobtrusive way of accessing the speech signal through existing speech infrastructure. The speech signal is discretized and processed through a digital signal processing algorithm, which extracts speech metrics from the signal that were determined to be indicative of fatigue levels. Speech metrics include, but are not limited to, speech duration, silence duration, word production rate, phrase gap duration, number of words per phrase and speech intensity. A fuzzy logic minimum inference engine maps the inputs to an output through an empirically determined rule base. The rule base and the associated membership functions were derived from batch mode and real time testing and the subsequent tuning of parameters to refine the detection of changes in patterns. To increase the validity and transparency of the output time series analysis is used to create the believability metric. A moving average filter eliminates the short term fluctuations and determines the long term trend of the output. A moving standard deviation estimation quantifies instantaneous fluctuations and provides a measure of the difference to a nominal alertness state. A real time version of the algorithm was developed and prototyped on a generic, low cost and scalable hardware platform. Rapid Prototyping was realized through the Matlab/Simulink xPC Target toolbox which allowed for instant real time code generation, testing and modification. This testing environment together with batch mode testing was used to extensively test and fine tune parameters to improve the performance of the algorithm. A testing procedure was developed and standardized to collect data and tune the parameters of the algorithm. As a high level goal it was proven that the concept of digital signal processing and Fuzzy Logic can be utilized to detect changes in speech and estimate alertness levels from it. Furthermore, this study has proven that the framework to run such an analysis continuously as a monitoring function in locomotive cabins is feasible and can be realized with relatively inexpensive hardware. The development, implementation and testing process conducted for this project is explained and results are presented here. / Ph. D.

This paper presents an experimental study with 47 participants on the influence of lighting on performance and well-being in an office environment. Well-being, alertness and performance were evaluated and measured in two rooms with artificial lighting and one room with day lighting. The evaluations were correlated to cortisol/melatonin saliva samples, illuminance and spectral compo-sition of the lighting. The results show day lighting to have a sustained influence on alertness and performance and it is furthermore concluded that the level of cortisol in saliva was not influenced by the illuminance and did not have an influence on performance. The participants preferred a lighting with different kinds of light sources to a more neutral lightning and gave it higher ratings for well-being.The analysis shows that comfort did not influence alertness.

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Rapid technological change and increasing traffic volumes worldwide are adding to the safety challenges for air traffic control. The night shift has traditionally been a period of low workload and work practices have evolved to reflect this. Thus, despite the exemplary safety record, there is a need to consider further systemic defences for maintaining performance and safety on the night shift. One possible strategy is the provision of a scheduled nap at work. In order to investigate the consequences of a scheduled nap on the night shift, 28 operational air traffic controllers were monitored across four roster cycles. Each roster cycle included one of two night shifts. Air traffic controllers were given a nap opportunity on one night shift of each type, and did not nap on the other. Information on the timing, quantity, and quality of sleep during the work week and days off was collected using actigraphy, and supported with logbook data. Sleep during the nap was measured using polysomnography, and the EEG and EOG were further utilised to determine neurophysiological alertness over the latter part of the night shift. Reaction time performance was measured three times across the night shift (beginning, middle, and end) with the psychomotor vigilance test.Actigraphy data indicated that the backward, rapidly-rotating work schedule of air traffic controllers resulted in a progressive loss of sleep across the work week. The reduction in sleep lead to an increasing cumulative sleep debt that was at a maximum prior to the night shift. This sleep debt was not related to reaction time performance at the end of the night shift, but was found to influence neurophysiological alertness.It was determined that the large majority of air traffic controllers were able to sleep during the scheduled 40 minute nap opportunity. However, the latency to sleep onset was long, the sleep short, and of relatively poor quality. Circadian and homeostatic factors increased the likelihood of entry into, and waking from, slow wave sleep (SWS). They were also found to influence reaction time performance and neurophysiological alertness. More variable performance and lowered alertness were seen at the end of the later starting (and finishing) night shift, possibly due to the combined influence of circadian and time-on-task factors. Homeostatic variables had less influence on performance at the end of the night shift, but greater acute sleep loss and higher cumulative sleep debts were related to increased neurophysiological sleepiness.performance and greater neurophysiological alertness in a dose-dependent manner, with even small amounts of stage 1 sleep effecting a performance improvement. Performance improvement was consistent across a range of reaction time measures and consistent improvements were also evident in the neurophysiological data, with the occurrence of SEMs declining, and lower spectral power evident in all frequency bands and single frequencies.These findings clearly demonstrate that a minimal quantity of sleep benefits the performance and alertness of air traffic controllers despite the "noise" of a field setting, thus providing a link between laboratory studies of napping and the actual work environment. The findings also fully support management endorsing a 40 minute napping opportunity for air traffic controllers working the night shift.The short nap sleep had no measurable effect on sleep subsequent to the night shift. However, the amount of sleep obtained in the nap was related to improved reaction time.

Opportunity has emerged as a focal point in the field of entrepreneurship and recognizing potential opportunities is the first step of new venture creation. A number of studies acknowledge the contributions of prior knowledge and social networks in explaining opportunity recognition. However, previous research ignored the importance of cognitive process. Thus, the purpose of this study is filling the research gap of the mediation mechanism in this process. Through the entrepreneurial cognitions view lens, this research goes a step further by asking:¡¨how do individuals conclude that an opportunity from their prior knowledge and information?¡¨ Entrepreneurial alertness, first used by Kirzner (1973) has been identified as a major factor in the process of opportunity recognition. We equate this cognitive ability with entrepreneurial alertness, proposing that this bridges the gap between knowledge/information and the innovativeness/number of opportunities. There are 3 studies in this research; first, Study 1 developed a scale of entrepreneurial alertness. Secondly, Study 2 conducted an experimental design research to test the relationships between prior knowledge, entrepreneurial alertness, and the number of opportunities. Thirdly, Study 3 collected large numbers sample to test the full model. Results indicate that prior knowledge and social networks had positive effects on entrepreneurial alertness. Moreover, entrepreneurial alertness was positively associated with the innovativeness and number of opportunities. In the mediating effect, interpretation ability was partially mediated the relationship between prior knowledge of markets, professional networks and opportunity recognition. This study contributed theoretical and practical implications. Future directions for research are described, and its practical implications for entrepreneurship education and entrepreneurs are examined.

Yes / An ability to act upon an entrepreneurial opportunity has been noted to be a major driver of new venture success. However, scholarly knowledge is limited on how and when entrepreneurs’ alertness to entrepreneurial opportunities drives new venture success. The current study addresses this gap in the entrepreneurship literature by arguing that variations in new venture performance are a function of levels of entrepreneurial alertness and networking capabilities. Using primary data gathered from 203 new ventures operating in a sub-Saharan African economy, Ghana, the study finds that increases in the levels of entrepreneurial alertness are related to increases in new venture performance. Additionally, the study finds that, under conditions of increased use of social and business networking capabilities, the potency of entrepreneurial alertness as a driver of new venture success is amplified. Theoretical, managerial and policy implications of these findings are discussed.

The vehicle routing problem (VRP), is a classic optimization problem that aims to determine the optimal set of routes for a fleet of vehicles to meet the demands of a set of customers. The VRP has been studied for many decades and as such, there are many variants and extensions to the original problem. The research presented here focuses on two different types of vehicle routing and scheduling planning problems: car shipping and fatigue-aware scheduling. In addition to modeling and solving the car shipping problem, this research presents a novel way for ways in which drivers can describe their route preferences in a decision support system. This work also introduces the first fatigue-aware vehicle scheduling problem called the Truck Driver Scheduling Problem with Fatigue Management (TDSPFM). The TDSPFM is utilized to produce schedules that keep the drivers more alert than existing commercial vehicle regulations. Finally, this work analyzes the effect of the starting alertness level on driver alertness for the remainder of the work week and examines a critical shortcoming in existing regulations. / Ph. D.

This work provides an innovative solution for monitoring fatigue for users behind workstations. A web camera was adjusted to work in near infrared range and a system of 880 nm IR diodes was implemented to create an IR vision system to localize and track the eye pupils. The software developed monitors and tracks eyes for signs of fatigue by measuring PERCLOS. The software developed runs on the workstation and is designed to draw limited computational power, so as to not interfere with the user task. To overcome low-frame rate imposed by the hardware limitations and to improve real time monitoring, two-phases detection and tacking algorithm is implemented. The proposed system successfully monitors fatigue at a rate of 8 fps. The system is well suited to monitor users in command centers, flight control centers, airport traffic dispatches, military operation and command centers, etc., but the work can be extended to wearable devices and other environments.

Le concept de vigilance entrepreneuriale introduit par Kirzner (1973) joue un rôle clé dans le processus de détection d’opportunités d’affaires. Depuis les travaux conduits par l’école autrichienne, ce concept a été largement développé et a soulevé un certain nombre de questionnements par les chercheurs. L’approche cognitive a permis d’apporter quelques éléments de réponses en affinant le concept. En s’inspirant des travaux initiaux de Kirzner (1973, 1989) et de ceux de l’approche cognitiviste, Tang et al. (2012) ont proposé une nouvelle définition plus intégratrice. Ces auteurs ont modélisé et opérationnalisé la vigilance entrepreneuriale autour de trois dimensions : la veille et la recherche d’informations, la capacité à faire des associations et des connexions entre les informations, et celle de les évaluer et de les juger. La question des antécédents potentiels de la vigilance entrepreneuriale restait en suspens (Valliere, 2013). En réponse à la remarque de Valliere (2013) et aux besoins de connaissances et de statistiques du champ de la santé entrepreneuriale, nous avons étudié les effets du sommeil sur ce processus. À cet effet, la théorie de l’attention a permis de faire des liens entre les champs de l’entrepreneuriat et du sommeil. Afin de répondre à la problématique, une posture positiviste, associée à un mode de raisonnement hypothético-déductif, a été adoptée. Treize hypothèses de recherche ont été proposées à partir desquelles le modèle conceptuel a été construit. Afin de le valider, une étude quantitative en coupe instantanée de deux mois a été conduite auprès de dirigeants de PME. À l’issue de cette enquête, 238 questionnaires ont été récoltés. Ces derniers ont été analysés par la méthode des équations structurelles basée sur les moindres carrés partiels (PLS). Les résultats soulignent l’importance du sommeil dans le maintien des capacités cognitives, attentionnelles et entrepreneuriales pour un dirigeant de PME. / The concept of entrepreneurial alertness introduced by Kirzner (1973) plays a critical role in the process of business opportunities detection. Since the work conducted by the Austrian school, this concept has been widely developed and has raised numerous questions by researchers. The cognitive approach has pointed to some answers by refining the concept. Inspired by the initial work of Kirzner (1973, 1989) and those conducted by the cognitive approach, Tang et al. (2012) proposed a more inclusive definition. These authors modeled and operationalized entrepreneurial alertness by three dimensions: alert scanning and search, alert association and connection and evaluation and judgment. The issue of potential antecedents of entrepreneurial alertness remained unresolved (Valliere, 2013). In response to the comments of Valliere (2013) and the entrepreneurial health field’s needs for knowledge and statistics, we proposed to study the effects of sleep on this process. To this end, the theory of attention allowed to make the links between the fields of entrepreneurship and sleep. To meet the problematic, a positivist posture associated with a hypothetical-deductive approach was adopted. Thirteen research hypotheses were proposed from the conceptual model was built. To validate this model, a cross sectional quantitative study of two months was conducted among SME owners/directors. At the end of this survey, we collected 238 questionnaires. These were analyzed by the structural equation method based on Partial Least Squares (PLS). The results highlight the importance of sleep in maintaining cognitive, attentional and entrepreneurial abilities for SME owners/directors.