Dissertations / Theses on the topic 'Alertness'
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1
Dodds, C. "Interactions between alertness and spatial awareness." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598574.
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Unilateral neglect, a common consequence of a stroke, involves a difficulty with detecting and responding to contralesional stimuli. It has been shown to be a heterogeneous syndrome, involving a cluster of deficits in both spatial and nonspatial functions. Studies have shown that patients with neglect can suffer from problems with sustained attention, spatial working memory, temporal processing, and alertness, as well as the more obvious deficits in spatial orienting. One of the most intriguing features of neglect is the widely observed hemisphere lateralisation of the disorder. Neglect is more common, and more persistent, after right hemisphere lesions. Attempts to explain this lateralisation have generally focussed on hemispheric differences in the control of spatial attention. Kinsbourne (1987), for example, suggests that the right hemisphere controls the ability to orient attention to both sides of space, whilst the left hemisphere is only able to orient attention to the right side of space. An alternative theory is that the right hemisphere is specialised for the control of certain nonspatial functions, and it is the presence of deficits in these right hemisphere-lateralised functions which exacerbates spatial orienting in patients with unilateral neglect. This thesis explores this latter hypothesis and its implications, using a variety of techniques, including psychophysiology, neuropsychology, functional neuroimaging, and psychopharmacology. The central hypothesis of the thesis is that there is a direct link between nonspatial factors and spatial awareness, such that declining alertness or reduced cognitive resources may be sufficient to induce a rightward shift in spatial bias.
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Spelten, Evelien Renate. "The relationship between age, sleep and health in shiftworking nurses." Thesis, University of Sheffield, 2000. http://etheses.whiterose.ac.uk/14788/.
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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.
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Allen, Andrew P. "Chewing gum's effects on alertness, performance and stress." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/47731/.
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Chewing gum has previously been found to reduce chronic stress and enhance alertness, but effects on attention have been less reliable. The aim of this thesis was to investigate possible mechanisms for such effects, and to study the reliability and timing of effects in greater detail. Two surveys provided detailed information about habitual gum consumption. Two intervention studies involved chewing gum during a workday and reporting well-being and performance at work; the second intervention also assessed physiological variables. Six experiments studied the timing of and mechanisms for acute chewing gum effects. Two of these experiments studied the prevalence of time-on-task trends in gum effects on attention and mood. A further experiment studied the effects of gum on mood in the absence of attention tasks. The final three experiments examined possible mechanisms for consistent effects of gum on alertness and variable effects on attention: the first concerned psychophysiology, the second concerned demand characteristics, and the third concerned rate of chewing and task order. The results of this thesis suggest that chewing gum can reliably maintain alertness and enhance reported performance at work. Chewing gum also moderated decrements in vigilance, although the direction of this effect depended on length of prior performance. A reduction of stress and anxiety was observed in some cases, but this finding was less reliable. Under experimental conditions, heart rate increased while chewing gum and began to slow following chewing, suggesting a physiological mechanism for both enhanced alertness and reduced stress. However, heart rate did not differ over the course of a workday. Salivary cortisol was higher during the morning when chewing gum, suggesting an endocrine response associated with higher alertness. Demand characteristics moderated reported alertness, but did not explain any effects on attention. Neither rate of chewing nor task order moderated chewing gum effects.
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Doyle, Colleen Elizabeth. "Effect of Short-Term Light Exposure on Alertness." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524088785098075.
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Shahidi, Parham. "Fuzzy Analysis of Speech Metrics to Estimate Crew Alertness." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/50436.
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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.
6
Roy, Jennifer. "Neuro-behavioural performance and self-assessed alertness in shiftworkers /." Title page and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09SB/09sbr888.-df.
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Neubauer, Catherine. "Alertness Maintaining Tasks: A Fatigue Countermeasure During Vehicle Automation?" University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1396522991.
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Slama, Hichem. "Task-goal switching: Influences of time, language, alertness and expertise." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/229285.
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Almost 100 years ago, Jersild (1927) published his article “Mental Set and Shift”. He borrowed this title from a book of Hollingworth and Poffenberger (1919), according to whom “shifting back and forth from one mental set, one attitude or one task to another, is a relatively ineffective mode of work.” As pointed out by Jersild, the cost of switching between activities or mental sets is, for instance, the reason for Taylor’s model of industrialization and the trend in industry toward specialization. Through specialization, the element of switch is reduced to its minimum because “the cost of shift is loss in efficiency” (Jersild, 1927). However, outside of the factory, switching between multiple tasks is a crucial part of human life and the cost of switching, consequently, impacts our everyday functioning.The main topic of this doctoral dissertation is cognitive flexibility and task switching. The task-switching paradigm requires participants to switch frequently between tasks. Therefore, it measures the capacity of our brain to adapt rapidly according to tasks and goals. Dynamic adaptation according to context and goals is encompassed in cognitive psychology and neurosciences under the term cognitive control. Consequently, the ability to switch between tasks constitutes the part of cognitive control that is needed when the current goal changes and the cognitive system has to adapt. Our experimental contribution aimed at investigating how this task-goal switching can be modulated by factors such as time, language, alertness and expertise. In this introduction, we succinctly review the vast literature about attentional systems, cognitive control and task switching. In the experimental section, we describe the cued match-to-sample task that we developed to investigate task-goal switching and present five experimental studies that address the impact of several factors on task-goal switching. In the general discussion, we summarize our results and consider their implications for cognitive-control and task-switching literatures.Doctorat en Sciences psychologiques et de l'éducation
info:eu-repo/semantics/nonPublished
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Karnali, Leona D. 1978. "Performance and alertness of railroad engineers on long duration trips." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27039.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004."February 2004."
Includes bibliographical references (leaves 89-91).
The present study investigated the performance and alertness of 8 healthy male participants between the age of 31 years and 65 years old in nighttime, long duration simulated train operation. Participants completed the simulator tasks twice, once alone (single run) and once with another person in the cab (paired run), on two different nights. Various simulator tasks were used to provide measurement of performance. Objective (percentage eyelid closure and psychomotor reaction time) and subjective (self reported fatigue, workload, and stress) were used to provide measurement of alertness. No significant result was found when comparing the performance and alertness measures between single and paired runs. The result showed significant correlation between the subjective measures and also between the subjective and objective measures. A significant difference in the temporal trend of performance decrement was found between the youngest and the oldest participants.
by Leona A. Karnali.
S.M.
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ROSSI, VALENTINA YOLANDA. "Integrating attention, alertness and control in the brain: an electrophysiological approach." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/7831.
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Converging evidences from neurophysiological, neuropsychological and functional neuroimaging literature suggested the involvement of a large-scale fronto-parietal network in the volitional and reflexive attentional control, which enables the biological systems to select relevant portions of the input stream for facilitating processing, in order to flexibly guide behavior on the basis of internal or external goals. This system acts in tight interplay with lateralized structures deputed to the achievement and maintenance of an adequate level of arousal, and with medial frontal structures responsible for the on-line modification of action and thought in response to an ever-changing external world. This project aims at clarifying the spatio-temporal dynamics of the recruitment of these three tightly related systems (alertness, orienting and executive control) and at a better explanation of integrative effects previously reported, by means of a series of high-density electrophysiological recording experiments combined with source localization methods. Experiment 1 combined a spatial cueing paradigm with a flanker task, showing early occipital and parietal activations in response to valid cues, and a lateralized pattern of sources for the responses of the phasic alertness system to both spatially valid and spatially neutral cues; additionally, we reported behavioral, electrophysiological and functional indexes of a modulation exerted by the orienting system upon the executive control one. Experiment 2 compared lateralized shifts of attention elicited by centrally and peripherally presented spatially valid and neutral cues, in a combined cueing and go/no-go task. The results again suggested an early involvement of the selective attention system in response to the task-relevant cues, as expressed in occipito-temporal enhanced responses to the valid cues as compared to the neutral ones; additionally, lateralized superior parietal and frontal activations were recorded, concurrently with attentional shifts. Again, a modulation of the conflict monitoring/response inhibition system was observed in case of validly cued stimuli, as indexed by anticipations of the fronto-central NoGoN2 in response to non-targets preceded by valid warning signals. Experiment 3 tested the hypothesis of bidirectional modulations between the attention and control systems, by means of an integrated stop-signal/flanker task. The results showed that the selective response inhibition, required in case of incompatible flankers in the primary stimuli, interfered with the attentional switch towards the relevant stop-signals, as reflected in dimmed auditory responses to the stop-tones. All in all, the present results point toward a complex interplay among the three systems, and suggest that any interpretation of the scientific results obtained in paradigms addressing the attentional networks should account also for alertness and executive control effects, which are indirectly manipulated when capitalizing on cueing/switching paradigms.
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Rodriguez, Mijael, and Albin Söderholm. "Measuring Student Alertness Using the X2-30 Eye-Tracker : A study in the suitability of the X2-30 eye-tracker to measure alertness in a learning environment." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-186438.
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This study has investigated the suitability of the eye-tracker X2-30 from Tobii when measuring a student’s alertness level. To be able to determine the suitability of the X2-30 two different environments and two different subjects has been used. The environments were a lecture and webinars, and the two subjects were the two male authors of this study. The results indicate that the eye-tracker X2-30 can be useful when it’s used under optimal circumstances (i.e. webinars), since it needs to have few disturbing factors when gathering data. These factors regard the subjects not moving out of the tracking area, i.e. the area of which the X2-30 is able to track the eye, and consequently it also means that the subject needs to be careful not to move the hardware. When used under optimal circumstances it was possible to obtain accurate data regarding pupil behaviour and somewhat accurate data regarding blink rate, making data relevant and the equipment suitable for measuring of alertness under the correct circumstances.Denna studie undersöker lämpligheten hos Tobii ABs X2-30 eye-tracker för att mäta en students vakenhet. För att avgöra lämpligheten så har tester gjorts i två olika miljöer och med två olika försökspersoner. Miljöerna var en föreläsning och ett flertal webinars medan försökspersonerna var de två manliga författarna av denna studie. Resultaten indikerar att X2-30 kan vara användbar när den används under optimala omständigheter, det vill säga webinars, då den kräver så få störande faktorer som möjligt. Dessa faktorer rör utrustningens mätzon och att försökspersonen inte lämnar denna, samt att hårdvaran inte flyttas under mätning. När utrustningen användes under optimala förhållanden så var det möjligt att få precis data rörande pupillens beteende och ganska korrekt data rörande blinkfrekvens vilket gör utrustningen lämplig för mätning av vakenhet under rätt omständigheter.
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Bareham, Corinne Anne. "Investigation of alertness as a modulator of spatial bias : rehabilitation of neglect." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648676.
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Stathi, Afroditi. "Physical activity and dimensions of subjective well-being in active older adults." Thesis, University of Bristol, 2001. http://hdl.handle.net/1983/41fb6bc3-ab50-4e93-aafe-39eb7afbc754.
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Keenan, Emma Kate. "Dietary interventions affecting sleep : effects on next day mood, alertness and cognitive function." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556729.
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The primary aim of this thesis was to evaluate the efficacy of dietary/herbal interventions on sleep, and associated daytime consequences that are often the major complaints of poor sleep in the general population. A secondary aim was to develop appropriate methodology for assessment of such interventions in 'the field.' Poor sleepers participated in two placebo-controlled, double-blind, 3-week field studies that included a baseline week, and were assessed after the first night, over two weeks, and at follow up. Outcomes included objective and self-rated measures of sleep, mood, and daytime cognitive performance, which had initially been assessed using caffeine as a model for poor sleep in good sleepers, and a separate sample of poor sleepers. Previously reported beneficial effects for sleep (or stress and anxiety hypothesised to promote healthy sleep) of hops, lemon balm, L- theanine, and a tryptophan rich protein were largely not replicated here. Nor were any clear beneficial effects observed for next day mood and cognitive performance. Although those with insomnia disorder were excluded, insomnia is often undiagnosed and possibly resulted in a sample of poor sleepers with severe sleep complaints. The selection criteria for poor sleepers are of major importance. Furthermore, different mechanisms must be targeted for short- or long-term sleep problems, and sleep needs to be poor enough to show evidence of daytime impairment. Objective daytime outcome measures are not suitable for daily field testing, as multiple nights of improved sleep are necessary to see measurable changes in performance, and these can be influenced by uncontrolled compensatory mechanisms deployed by participants to manage the effects of their poor sleep. For the purpose of assessing changes associated with improved sleep due to interventions in poor sleepers without insomnia disorder, self-rated performance may be a more appropriate and reliable outcome. Feeling refreshed in the morning may be another important primary outcome variable, as this was found to be associated with both sleep quality and daytime performance.
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Hoppen, Katherine Edith. "The effects of light on alertness and performance in relation to melatonin secretion." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/807466/.
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Cognitive performance and alertness are severely compromised during the night compared to the day. This lowered alertness and performance has implications for night shift workers, employers and the general public: a higher number of accidents occur during the night shift. Countermeasures suggested for these alertness and performance decrements include the use of bright light (BL), napping and caffeine. A series of experiments was carried out to test systematically whether BL did indeed improve nocturnal alertness and performance. The first experiment established that 2hrs of bright light (broad spectrum white, 02:00-04:00h, 10,000lux) did improve subjective alertness and performance. The timing, duration and wavelength of light was then investigated. It was concluded that BL given in the middle of the night (white 00:00-01:00h, 10,000lux) was more effective than light given at 20:00h or 04:00h. Light of 2hrs and 4hrs duration were more effective than 1 hr of light centred at 03:00h (white, 10,000lux). Light of shorter wavelengths appeared to be more effective than light of longer wavelengths at improving nocturnal alertness and performance (01:00-05:00h, ~300lux). The mechanism by which bright light exerted its effect was investigated and, for certain measures (subjective fatigue, feeling awake and performance on the digit symbol substitution task), the improvement seen with bright light treatment was abolished with concomitant melatonin administration (2mg, 00:15h) suggesting that for these measures bright light may exert its effect through melatonin suppression. The effects of bright light (white, 03:00-03:10h, 10,000lux) and/or caffeine (300mg) on sleep inertia after a 1hr nocturnal nap were also investigated and it was concluded that both BL and caffeine can decrease the sleep inertia effect. The results from the work contained in this thesis suggest that BL may be a useful countermeasure to lowered alertness and performance during the night.
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Purnell, Melissa T., and n/a. "Sleep, alertness, performance and fatigue management in extended duration and irregular night shift workers." University of Otago. Dunedin School of Medicine, 2005. http://adt.otago.ac.nz./public/adt-NZDU20061030.085607.
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Extended duration and irregularly planned overnight shifts are becoming frequent features of current working time arrangements. However, there is great concern about the detrimental effect that these shifts are likely to have on the sleep, performance and fatigue levels of workers. To date, the empirical evidence regarding the effects of extended and irregular overnight shifts is sparse and workers have rarely been followed up longer term to assess possible changes over time. Because these types of overnight shifts are being introduced into transport settings such as aviation and shipping where safe and productive operations are paramount, there is a real imperative to examine and trial workplace-based methods aimed at counteracting night shift related fatigue and performance deficits. Taking short duration naps on the nightshift at work is one potential countermeasure that has shown promise in the laboratory but has yet to be examined in any real-world setting under conditions of extended duration or irregular night work. This thesis takes up these issues in a series of four empirical workplace-based studies.
The impact of the introduction of regularly planned 12 h day and overnight shifts was examined on three occasions via questionnaire in a group of aircraft maintenance engineers, once before the change, and twice after the change from 8 h shifts. The results showed that high levels of acute fatigue on the 12 h night shifts and high chronic fatigue levels were common, and were strongly associated with poor overall job performance, poor safety of job performance, and longer recovery times, effects that persisted over time. Of major concern was the finding that over half of the engineers reported having nodded off while driving home from their extended overnight shifts. The impact of irregularly planned 8 h overnight shifts worked by cargo handlers in a shipping container terminal was also examined via self-report questionnaire. The findings revealed significant detrimental impacts on sleep, fatigue levels and performance at work. High fatigue levels were strongly associated with poor self-rated performance output and safety of performance at work on the overnight shifts.
The primary focus of this thesis was to evaluate the effect of a scheduled 20 min nap opportunity taken in these two fully operational workplaces during the night shift on sleep, performance and alertness. Sleep was achieved by 50 to 59% of workers. Speed of performance in 24 male aircraft maintenance engineers on a vigilance task was significantly faster at the end of a 12 h overnight shift that had contained sleep during the nap compared to the control condition. There was no such effect of the nap on the performance of 22 cargo handlers working impromptu 8 h shifts in a shipping container terminal. However, the duration of sleep obtained by the 8 h workers was shorter in comparison and was likely to have been undermined by the high noise levels around the nap facility and time pressures related to the organisation of work. Actigraphy data recorded from all subjects showed that subsequent daytime sleep was not disrupted by the night shift nap opportunity. Overall, the most interesting findings were that simply being tired and presented with a sleep opportunity during the night shift did not guarantee either sleep, or recovery but that sleep, as opposed to rest, was necessary for the benefits to performance to be fully realised.
These findings have shown for the first time that management of fatigue associated with extended duration night work can be achieved in some instances by the use of a short duration nap taken in the workplace on the night shift. However, operationalizing in-situ napping on the night shift has a range of organisational influences that must be considered for the potential of such a strategy to be fully harnessed.
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Shekari, Soleimanloo Shamsi. "Effects of light and caffeine on human sleepiness and alertness: A simulated driving experiment." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/95888/1/Shamsi_Shekari%20Soleimanloo_Thesis.pdf.
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This thesis examined the effects of a novel blue-green light intervention, together with caffeine, on sleepiness and driving performance in young adults, a population that is overrepresented in sleepiness-related road crashes. Light, caffeine, and the combination of light and caffeine each improved alertness after chronic-partial sleep deprivation to a greater extent than did a placebo. Each condition improved subjective sleepiness, objective psychomotor performance, and objective driving performance, with the greatest effect found for light and caffeine in combination. These findings have implications for interventions to reduce mortality and morbidity associated with road crashes.
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Kronqvist, Annika. "The influence of the lighting environment on performance and well-being in offices." Tekniska Högskolan, Högskolan i Jönköping, JTH, Belysningslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-21468.
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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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Bowden, Zachary E. "Behavioral Logistics and Fatigue Management in Vehicle Routing and Scheduling Problems." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/79792.
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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.
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Pavy, Alan. "The effects of chewing on cognitive performance and subjective alertness during a night of sleep deprivation /." Title page, abstract and table of contents only, 2003. http://web4.library.adelaide.edu.au/theses/09ARPS/09arpsp3392.pdf.
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Haupt, Marleen [Verfasser], and Kathrin [Akademischer Betreuer] Finke. "Phasic alertness and intrinsic functional connectivity in healthy and pathological aging / Marleen Haupt ; Betreuer: Kathrin Finke." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1218465484/34.
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Signal, T. Leigh. "Scheduled napping on the night shift : consequences for the performance and neurophysiological alertness of air traffic controllers : a thesis submitted for the degree of Doctor of Philosophy of the University of Otago, Dunedin New Zealand." Massey University, 2002. http://hdl.handle.net/10179/233.
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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.
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Wright, Nicola Anne. "Central effects of antihypertensive drugs in man : pharmacological modification of the electrical activity of the brain and changes in alertness." Thesis, Open University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336975.
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Friedrichs, Fabian [Verfasser], and Bin [Akademischer Betreuer] Yang. "Driver alertness monitoring using steering, lane keeping and eye tracking data under real driving conditions / Fabian Friedrichs ; Betreuer: Bin Yang." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1214242359/34.
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Quinn, Maria. "Ljusterapi för nattpersonal inom slutenvården." Thesis, Halmstad University, School of Social and Health Sciences (HOS), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-1013.
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En stor del av personalen inom Hälso- och Sjukvården har sin arbetstid förlagd till natten. Vi vet idag att det är mycket ogynnsamt att arbeta nattetid och att det höjer risken att utveckla flera sjukdomar. Nattarbete och roterande skiftarbete stör och påverkar den naturliga dygnsrytmen i kroppen. Kan vi hjälpa kroppen att anpassa sig bättre till nattskiftsarbete med hjälp av ljusterapins effekter? Ljusterapi är, vad vi känner till idag, en säker behandling med få eller inga biverkningar. Den är lätt att administrera, relativt billigt och flexibel att utföra. Det optimala verkar vara, enligt vår nuvarande kunskap, att få ljusterapibehandling intermittent under nattpasset, kombinera detta med att använda sig av mörka solglasögon när man tar sig hem samt sedan att lägga sig att sova så snart som möjligt efter hemkomsten i ett mörkt rum. Ljusterapi hjälper speciellt inför längre perioder av nattpass men har också en mycket god effekt på att återställa den inre klockan till dag-dygnsrytm igen efter avslutad nattperiod. Ljusterapibehandling visar sig hjälpa även mot problem med ett förtidigt uppvaknande, som är ett vanligt fenomen vid nattarbete, och effekten av behandlingen kan kvarstå i upp till en månad. Den positiva höjningen av funktionsnivån som även inträffar kan också kvarstå så länge.
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Fischer, Johanna Dorothea [Verfasser]. "Veränderungen neuronaler Aktivität bei präsymptomatischen Mutationsträgern der Huntington Krankheit - Eine funktionell magnetresonanztomographische Untersuchung der intrinsischen und phasischen Alertness / Johanna Dorothea Fischer." Ulm : Universität Ulm. Medizinische Fakultät, 2015. http://d-nb.info/1080331433/34.
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Petrilli, Renèe Marcia. "Alertness, sustained attention, and perception during 24 hours of wakefulness : the effects of fatigue and functional energy drinks on human decision-making /." Title page, table of contents and abstract only, 2003. http://web4.library.adelaide.edu.au/theses/09HS/09hsp495.pdf.
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Belz, Steven Mark. "An On-Road Investigation of Commercial Motor Vehicle Operators and Self-Rating of Alertness and Temporal Separation as Indicators of Driver Fatigue." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29589.
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This on-road field investigation employed, for the first time, a completely automated, trigger-based data collection system capable of evaluating driver performance in an extended duration real-world commercial motor vehicle environment. The complexities associated with the development of the system, both technological and logistical and the necessary modifications to the plan of research are presented herein
This study, performed in conjunction with an on-going three year contract with the Federal Highway Administration, examined the use of self-rating of alertness and temporal separation (minimum time-to-collision, minimum headway, and mean headway) as indicators of driver fatigue. Without exception, the regression analyses for both the self-rating of alertness and temporal separation yielded models low in predictive ability; neither metric was found to be a valid indicator of driver fatigue. Various reasons for the failure of self-rating of fatigue as a valid measure are discussed. Dispersion in the data, likely due to extraneous (non-fatigue related) factors (e.g., other drivers) are credited with reducing the sensitivity of the temporal separation indicators.
Overall fatigue levels for all temporal separation incidents (those with a time-to-collision equal to or less than four seconds) were found to be significantly higher than for those randomly triggered incidents. On this basis, it is surmised that temporal separation may be a sensitive indicator for time-to-collision values greater than the 4-second criterion employed in this study.
Two unexpected relationships in the data are also discussed. A "wall" effect was found to exist for minimum time-to-collision values at 1.9 seconds. That is, none of the participants who participated in this research effort exhibited following behaviors with less than a 1.9-second time-to-collision criterion. In addition, based upon the data collected for this research, anecdotal evidence suggests that commercial motor vehicle operators do not appear to follow the standard progression of events associated with the onset of fatigue.Ph. D.
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Matthias, Ellen. "The influence of the level of alertness on spatial and non-spatial components of visual attention in healthy subjects and neglect patients." Diss., kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/8898/.
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Ratecki, Tomasz. "Fatigue Monitoring System." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1141.
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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.
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Elms, Henrietta. "Effects of the Deep Meditative Relaxation Technique (DMRT) On Nocturnal Self-Awakening Sleep/Wake Quality Among University Students." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353950254.
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Boumedjaoud, Dorian. "Identification des opportunités par le repreneur de PME : le rôle du mentorat." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTD032/document.
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750 000 emplois à sauvegarder. Ce nombre – mis en avant par l'ancienne députée de l'Hérault, Fanny Dombre-Coste, – souligne toute l'influence de la reprise de PME dans le développement de l'économie locale voire nationale. Toutefois, le repreneur, qui est un entrepreneur à part entière, est un acteur encore peu étudié, tant par les organismes professionnels que par les universitaires. Nous engageons alors une recherche pour combler ce manque et, sous une perspective entrepreneuriale, essayons de mieux comprendre le profil du repreneur. Pour circonscrire la question du profil, nous utilisons un concept central en entrepreneuriat : l'opportunité. Dès lors, en prenant appui sur la logique de Kirzner, la fonction du repreneur devient plus claire : il doit identifier des opportunités. Comment peut-il faire ? Il va utiliser sa vigilance. Cela nous amène à poser la problématique suivante : comment la vigilance entrepreneuriale du repreneur influence-t-elle la performance financière de la reprise ? Pour apporter des éléments de réponse, nous utilisons un raisonnement hypothético-déductif et réalisons une recherche quantitative. Cela nous amène à formuler des hypothèses pour in fine construire un modèle de recherche. Nous posons ainsi un lien entre la vigilance entrepreneuriale (Tang et al., 2012) et deux variables médiatrices : l'identification des opportunités (Ozgen et Baron, 2007) et l'orientation entrepreneuriale (Covin et Slevin, 1989). Ces deux variables sont ensuite reliées à la performance financière de la reprise – qui est une mesure subjective quant à l'évolution de huit indicateurs. Après avoir montré que la procédure MICIOM autorise une démarche comparative, nous testons notre modèle sur tous les repreneurs (n = 278) et procédons à une comparaison – qualitative puis grâce à une analyse multigroupe – entre les repreneurs mentorés (n = 199) et non mentorés (n = 79), et entre les repreneurs mentorés avant (n = 79) et après la reprise (n = 120). Les résultats de cette recherche montrent que la vigilance entrepreneuriale est un antécédent de la performance financière. Par ailleurs, ce travail souligne que le mentorat permet de mieux comprendre comment un entrepreneur réussit – au moins sur un plan financier – une reprise de PME. Dès lors, il semble pertinent de développer un volet cognitif dans les programmes d'accompagnement du repreneur mais également de travailler sur la relation de mentorat dans ce contexte singulier750 000 employments to keep. This number, highlight by the former deputy of Herault, Fanny Dombre-Coste, underline influence of SME takeovers on development of local economy. However, buyer, an entrepreneur, is understudied. We then engaged an academic research in order to fill in this gap and, using an entrepreneurial perspective, we try to better understand buyer profile. To confine profile question, we use a central concept in entrepreneurship: opportunity. Then, leaning on Kirzner logic, buyer function become clearly: he has to identify opportunity. How can he do it? He is going to use his alertness. So, we ask the following problematic: how does buyer entrepreneurial alertness influence takeover financial performance? To answer, we use an hypothetico-deductive reasoning and realise a quantitative research. This lead us to formulate hypotheses and build a research model. We put a link between entrepreneurial alertness (Tang et al., 2012) and two mediator's variables: opportunity identification (Ozgen et Baron, 2007) and entrepreneurial orientation (Covin et Slevin, 1989). Then, this two variables are linked to takeover financial performance – which is a subjective measure of the evolution of height indicators. After used MICOM procedure, we test our model on all buyers (n = 278) and make a comparison – qualitative and using a multi-group analysis – between buyers supported by a mentor (n = 199) and non-supported (n = 79), and between buyers supported before (n = 79) and after takeover (n = 120). Firstly, results show that entrepreneurial alertness is an antecedent of financial performance. On the other hand, our research underline that mentorship has the potential to add substantially to our understanding of how buyer succeed – at least on an financial plan – SME takeover. Consequently, it seems relevant to develop a cognitive part in buyer support program and to work on mentorship in this singular context
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Abas, Ashardi B. "Non-intrusive driver drowsiness detection system." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5521.
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The development of technologies for preventing drowsiness at the wheel is a major challenge in the field of accident avoidance systems. Preventing drowsiness during driving requires a method for accurately detecting a decline in driver alertness and a method for alerting and refreshing the driver. As a detection method, the authors have developed a system that uses image processing technology to analyse images of the road lane with a video camera integrated with steering wheel angle data collection from a car simulation system. The main contribution of this study is a novel algorithm for drowsiness detection and tracking, which is based on the incorporation of information from a road vision system and vehicle performance parameters. Refinement of the algorithm is more precisely detected the level of drowsiness by the implementation of a support vector machine classification for robust and accurate drowsiness warning system. The Support Vector Machine (SVM) classification technique diminished drowsiness level by using non intrusive systems, using standard equipment sensors, aim to reduce these road accidents caused by drowsiness drivers. This detection system provides a non-contact technique for judging various levels of driver alertness and facilitates early detection of a decline in alertness during driving. The presented results are based on a selection of drowsiness database, which covers almost 60 hours of driving data collection measurements. All the parameters extracted from vehicle parameter data are collected in a driving simulator. With all the features from a real vehicle, a SVM drowsiness detection model is constructed. After several improvements, the classification results showed a very good indication of drowsiness by using those systems.
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Korim, Willian Seiji. "Vias centrais purinérgicas envolvidas na regulação do fluxo sangüíneo muscular durante os comportamentos de alerta e defesa." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-06022007-175231/.
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As reações de alerta e defesa compreendem ajustes cardiovasculares proporcionando um fluxo sangüíneo muscular adequado nas situações de \"luta ou fuga\". As vias centrais e os possíveis neurotransmissores envolvidos nestes ajustes permanecem ainda, em grande parte, desconhecidas. Neste estudo buscamos analisar a participação da neurotransmissão purinérgica e glutamatérgica no núcleo do trato solitário (NTS) na gênese da vasodilatação muscular durante reações de defesa e o papel das vias glutamatérgicas do NTS para o núcleo rostroventrolateral (RVL) nestas respostas. Ratos Wistar machos (250-350 g) foram anestesiados (uretana 600 mg/kg + alpha-chloralose 50 mg/kg, i.v.), paralisados (d-Tubocurarina, 0,5 mg/kg, i.v.) e ventilados artificialmente. Registramos a pressão arterial média (PAM), a freqüência cardíaca (FC) e o fluxo sangüíneo dos membros posteriores (FSMP). A condutância vascular dos membros posteriores (CVMP) foi determinada como a razão FSMP/PAM e expressa como percentagem do valor basal. A estimulação elétrica (EE; 150 MuA; 0,6 ms; 100 Hz; 6 s) do hipotálamo lateral provocou hipertensão, taquicardia e vasodilatação nos membros posteriores. A microinjeção bilateral de suramin (100 pmol/50 nl), um antagonista não específico de receptores P2x no NTS, reduziu a vasodilatação nos membros posteriores durante a EE do hipotálamo (173±19,0 vs 28±14,1% do basal) sem alterar as respostas pressora e taquicárdica. A microinjeção do agonista P2x alpha, beta-methylene ATP (100 pmol/50 nl) no NTS produziu hipotensão, bradicardia e vasodilatação dos membros posteriores. A microinjeção de suramin (100 pmol/50 nl) bloqueou a vasodilatação muscular (76±15,2 vs 9±2,1% do basal) e a hipotensão (-47±4,5 vs -6±2,0 mmHg). A microinjeção de ácido quinurênico (4 nmol/50 nl), um antagonista glutamatérgico ionotrópico não seletivo no NTS bloqueou, de forma semelhante ao suramin, a vasodilatação durante a EE do hipotálamo (134±21,5 vs 27±12,7% do basal) sem alterar as respostas pressora ou taquicárdica. O bloqueio bilateral no RVL com microinjeções de ácido quinurênico reduziu intensamente a resposta hipotensora (-60±6,1 vs -9±3,7 mmHg) e vasodilatadora (126±16,9 vs 17±4,6% do basal) provocada pelas microinjeções de alpha, beta-methylene ATP (100 pmol/50 nl) no NTS. O agonista purinérgico A2a, CGS21680 (20 pmol/50 nl) no NTS, evocou hipotensão, bradicardia e vasodilatação muscular de longa duração. O bloqueio do RVL com ácido quinurênico (4 nmol/50 nl) reduziu a hipotensão (- 41±4,7 vs -7±1,9 mmHg), a bradicardia (-33±9 vs -10±3,1 bpm) e a vasodilatação nos membros posteriores (81±5,6 vs 8±1,5% do basal). Estes resultados sugerem que a vasodilatação muscular nas repostas de defesa depende da ativação de receptores P2x e receptores glutamatérgicos no NTS. Ajustes cardiovasculares por ativação dos receptores purinérgicos P2x e A2a no NTS provocam vasodilatação muscular que depende da liberação de glutamato no RVL, provavelmente ativando interneurônios inibitórios ali presentes.The electrical stimulation (ES) of the hypothalamus in the rat produces a well- defined pattern of cardiovascular adjustments including hypertension, tachycardia and skeletal muscle vasodilation. These hemodynamic responses can also be observed in natural conditions during fight and/or flight behaviors. However the neural pathways and possible neurotransmitters involved remain largely unknown. In this study we sought to determine the role of purinergic and glutamatergic receptors into the nucleus tractus solitarius (NTS) in the cardiovascular responses induced by hypothalamic ES, also we aimed to analyze the role of glutamatergic neural pathways from the NTS to the rostral ventrolateral medulla (RVLM) in these responses. Male Wistar rats (250-350 g) were anesthetized (urethane 600 mg/kg + alpha-chloralose 50 mg/kg, iv), paralyzed (d-tubocurarine 0.5 mg/kg, iv) and artificially ventilated. Mean arterial blood pressure (MAP), heart rate (HR) and hindquarter blood flow (HQBF) were recorded. Hindquarter vascular conductance (HQVC) was calculated as the ratio HQBF/MAP and expressed as percentage of baseline. Hypothalamic ES (6s trains, 0.6 ms square pulses, 100 Hz, 150 MuA) evoked a transitory hypertension, tachycardia and hindlimb muscle vasodilation. After bilateral microinjections of suramin (100 pmol /50 nl), a non-specific P2x receptor antagonist, into the NTS the hindlimb vasodilation was reduced (173±19.0 vs 28±14.1% of baseline), even so the transitory hypertension and tachycardia remained unchanged. A similar vasodilation reduction (134±21.5 vs 27±12.7% of baseline) was observed after microinjections of kynurenic acid bilaterally at the same NTS sites. Microinjections of the P2x receptor agonist alpha, beta-methylene ATP (100 pmol/50 nl) into the NTS produced hypotension, bradycardia and hindlimb muscle vasodilation. Bilateral microinjections of suramin at the same NTS site reduced the hypotension (-47±4.5 vs -6±2.0 mmHg) and the vasodilation (76±15.2 vs 9±2.1% of baseline). After bilateral microinjection of kynurenic acid into the RVLM, both hypotension (-60±6.1 vs -9±3.7 mmHg) and the vasodilation response (126±16.9 vs 17±4.6% of baseline) induced by alpha, beta- methylene ATP into the NTS were reduced. The A2a agonist CGS21680 (20 pmol/50 nl) into the NTS produced a long-lasting hypotension, bradycardia and hindlimb vasodilation. Bilateral RVLM glutamatergic blockade reduced the hypotension (-41±4.7 vs -7±1.9 mmHg), the tachycardia (-33±9.0 vs -10±3.1 bpm) and the muscle vasodilation (81±5.6 vs 8±1.5% of baseline) when CGS21680 was injected into the NTS. Therefore the results suggest that in alerting defense reaction, hindquarter vasodilation is mediated by NTS P2x and also by glutamatergic receptors into the intermediate NTS. Cardiovascular responses evoked by either P2x or A2a receptors stimulation in the NTS are mediated by glutamatergic synapses into the RVLM probably through activation of inhibitory interneurones in this area.
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Levasseur, Ludvig. "Temps, opportunité, stratégie, croissance et PME." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLED056/document.
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Les recherches en Management/Organisation ont quelque peu mis de côté la Perspective Temporelle ou PT (selon Lewin, la somme des points de vue individuels à un moment donné sur le passé et le futur psychologique). Cette Thèse étudie comment le(la) dirigeant(e) et sa PME agissent pour générer de la croissance en se focalisant sur la PT. Les questionnaires et les entretiens avec les 22 dirigeant(e)s d’entreprises (effectif : 10-49 salariés) permettent la mise au jour de leurs PT mais aussi des liens entre les différentes composantes du cadre conceptuel (ex : l’orientation entrepreneuriale de la firme, la vigilance individuelle) et d’autres éléments importants (ex : les biais cognitifs). La construction et les comparaisons des 22 cartes cognitives permettent également la mise au jour des différentes trajectoires de croissance et le questionnement de « l’équilibre » de la PT comme critère « discriminant ». Enfin, un modèle à tester et des directions de recherche sont proposésOrganization and Management studies have somewhat neglected Time Perspective (TP), which is, according to Lewin, the sum of the individual’s viewpoints of his psychological past and future existing at a given time. This dissertation examines how small and medium-sized enterprise (SME) owner-managers and their firms generate growth, with a focus on TP. Questionnaires and qualitative interviews with 22 SME owners (10‒49 employees) revealed individual TPs and links among diverse components of the conceptual framework (e.g., alertness, entrepreneurial orientation) and other important factors (e.g., cognitive biases). The 22 cognitive maps also showed several firm growth trajectories and raised questions about the “balanced” TP as a discriminating criterion. Last, a model and directions for future research are proposed
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Guiliani, Florence. "La vigilance entrepreneuriale : les antécédents liés au sommeil du dirigeant de PME." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTD014/document.
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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 PMEThe 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
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Neverosky, Daniel Thomas, and Aileen Kenney. "Quantifying sleep and performance of West Point cadets: a baseline study." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1565.
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Approved for public release, distribution is unlimitedThis study reports the initial findings of a four-year longitudinal study undertaken to assess the total amount of sleep received by cadets at the United States Military Academy. Specifically, data on the Class of 2007 were collected and analyzed during the freshman year. Survey data were collected (n=1290) on sleep habits prior to the cadets reporting to the Academy. Actigraphy data were collected (n=80) during summer military training and during the Fall academic semester. Survey data were analyzed using two different methods to determine total amount of sleep prior to reporting to the Academy ( x =8.5 hrs, s.d.=1.7 hrs; x =7.76 hrs, s.d.=1.46 hrs). Actigraphy data revealed that cadets received much less nighttime sleep (naps not included) during the Fall academic semester than they reported receiving in the month before CBT (total: x =5.32 hrs, s.d.=35.3 mins; school nights: x =4.86 hrs, s.d.= 37.4 mins; non-school nights: x =6.56 hrs, s.d.=64.4 mins). Using morningness/eveningness chronotypes, owls and non-owls differed significantly along the following dimensions: cadet attrition (z=2.66, p=0.0039), fall term academic quality point average (t=3.92, p<0.001), military program score (t=5.169, p<0.001), and physical program score (t=3.295, p=0.001). Suggestions for additional analysis of existing and subsequent data are proposed.
United States Military Academy, West Point, NY
Ensign, United States Naval Reserve
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CROCAMO, CRISTINA. "The Digital–Alcohol Risk Alertness Notifying Network for Adolescents and Young Adults Project (D-ARIANNA): Risk estimation model and impact of a mobile eHealth Intervention on Binge Drinking in Young People." Doctoral thesis, Università degli studi di Pavia, 2017. http://hdl.handle.net/11571/1203389.
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Background. The Digital–Alcohol Risk Alertness Notifying Network for Adolescents and Young Adults Project (D-ARIANNA) addresses a topic of growing interest in the field of substance abuse among adolescents and young adults, i.e., risk estimation models for binge drinking (BD) using eHealth apps. According to relevant research, this study novelty value may bring an important contribution to the substance abuse community. BD is common among young people, but often risk is not recognized. eHealth apps, attractive for young people, may be useful to enhance awareness of this problem. We aimed to develop a risk estimation model for BD, incorporated into an eHealth app, D-ARIANNA, for young people.
Methods. A longitudinal approach with phase 1 (risk estimation), phase 2 (design), phase 3 (feasibility study) was followed. Ten risk and two protective factors identified from the literature were used to develop a current risk estimation model for BD. Relevant odds ratios were pooled through meta-analytic techniques, deriving weighted estimates to be introduced in a final model. The model, nested in an eHealth app interview, provided in percent an overall risk score, accompanied by appropriate images and a summary message with factors that mostly contributed. The D-ARIANNA questionnaire, matching identified risk factors, was assessed for wording, content and acceptability. Feasibility study was a quasi-experimental, pre-/post-test study. Subjects were recruited in pubs, discos, or live music events in Milan urban locations. They were requested to self-administer D-ARIANNA and were re-evaluated after 2 further weeks.
Feasibility Study Results. Young (18–24 years) people (N = 590) reported reduced two-week BD (18% vs. 37% at baseline). Most of subjects considered D-ARIANNA helpful. To exclude systematic errors involving those lost at follow-up (14%), the diminution in BD was also evaluated through an appropriate generalized estimating equation model.
Conclusions. D-ARIANNA is the first evidence-based eHealth app for BD in young people, cited in the European Monitoring Centre for Drugs and Drug Addiction (http://www.emcdda.europa.eu/html.cfm/index98829EN.html) and the NHS health apps libraries (http://apps.nhs.uk/apps/alcohol/). Although a more advanced study is pending by through of an adequately powered trial, the promising results point to the potential of a smartphone tool for preventing relapse in BD and its application in real word practice, thus enabling further studies. D-ARIANNA, focused on personal communication and BD risk awareness, influences responsible drinking, and could be tested in an environmental-based community intervention.
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Liljenberg, Anders. "Customer-geared competition : a socio-Austrian explanation of Tertius Gaudens." Doctoral thesis, Stockholm : Economic Research Institute, Stockholm School of Economics (Ekonomiska forskningsinstitutet vid Handelshögsk.) (EFI), 2001. http://www.hhs.se/efi/summary/552.htm.
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Indlekofer, Friedrich J., Michaela Piechatzek, Marcel Daamen, Christoph Glasmacher, Roselind Lieb, Hildegard Pfister, Oliver Tucha, Hans-Ulrich Wittchen, and Christian G. Schütz. "Reduced memory and attention performance in a population-based sample of young adults with a moderate lifetime use of cannabis, ecstasy and alcohol." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-106791.
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Regular use of illegal drugs is suspected to cause cognitive impairments. Two substances have received heightened attention: 3,4-methylenedioxymethamphetamine (MDMA or ‘ecstasy’) and δ-9-tetrahydrocannabinol (THC or ‘cannabis’). Preclinical evidence, as well as human studies examining regular ecstasy consumers, indicated that ecstasy use may have negative effects on learning, verbal memory and complex attentional functions. Cannabis has also been linked to symptoms of inattention and deficits in learning and memory. Most of the published studies in this field of research recruited participants by means of newspaper advertisements or by using word-of-mouth strategies. Because participants were usually aware that their drug use was critical to the research design, this awareness may have caused selection bias or created expectation effects. Focussing on attention and memory, this study aimed to assess cognitive functioning in a community-based representative sample that was derived from a large-scale epidemiological study. Available data concerning drug use history allowed sampling of subjects with varying degrees of lifetime drug experiences. Cognitive functioning was examined in 284 young participants, between 22 and 34 years. In general, their lifetime drug experience was moderate. Participants completed a neuropsychological test battery, including measures for verbal learning, memory and various attentional functions. Linear regression analysis was performed to investigate the relationship between cognitive functioning and lifetime experience of drug use. Ecstasy and cannabis use were significantly related to poorer episodic memory function in a dose-related manner. For attentional measures, decrements of small effect sizes were found. Error measures in tonic and phasic alertness tasks, selective attention task and vigilance showed small but significant effects, suggesting a stronger tendency to experience lapses of attention. No indication for differences in reaction time was found. The results are consistent with decrements of memory and attentional performance described in previous studies. These effects are relatively small; however, it must be kept in mind that this study focussed on assessing young adults with moderate drug use from a population-based study.
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Dali, Souhir. "Study of the temporal deployment of attention : identification and characterization of psychological, neural and physiological indicators of mental effort." Thesis, Paris 10, 2019. http://faraway.parisnanterre.fr/login?url=http://bdr.parisnanterre.fr/theses/intranet/2019/2019PA100168/2019PA100168.pdf.
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L'objectif principal de cette thèse est de montrer que l’entrainement mental (EM) induit par imagerie motrice entraine un déploiement temporel de l'attention et optimise la préparation temporelle. Le deuxième objectif est de montrer que lorsque l'effort mental est maintenu une longue période, il peut entraîner une fatigue mentale. Nous essayons de trouver des marqueurs psychologiques, neurologiques et physiologiques de l'effort mental pour mieux caractériser la fatigue mentale. Dans la première étude, nous avons montré que l’entraînement mental optimisait les attentes temporelles pour les courts foreperiods « FP » avec un renforcement de la connectivité effective entre l'insula antérieure (AI) et le cortex cingulaire antérieur (ACC), l'AI et le cortex préfrontal dorsolatéral (DLPFC) (FP = 250/280ms: alerte intrinsèque) et entre le DLPFC et l'ACC (FP=650ms : alerte extrinsèque). La deuxième étude a montré après l'imagerie motrice, une augmentation des temps de réaction vers la fin de la tâche pour l’alerte intrinsèque (FP=250/280 ms) avec une diminution de la connectivité entre AI-ACC et AI-DLPFC. Nous suggérons que la FP et l’EM pourraient jouer un rôle dans le déploiement temporel de l'attention et constitueraient des marqueurs psychologiques et neurologiques de l'effort mental via le réseau AI-ACC-DLPFC. Dans la troisième étude, nous avons examiné la relation entre l'effort mental et une composante physiologique «cortisol». Les résultats ont montré que la concentration de cortisol était élevée au niveau de la tâche d’imagerie et était liée à l'augmentation de l'activité de l'hypothalamus et du tronc cérébral. Cette étude montre que ces régions pourraient jouer un rôle dans la régulation de la sécrétion de cortisol en réponse à une situation cognitivement exigeanteThe main objective of this thesis is to show that attentional reinforcement induced by an intensive short session of mental training (MT), induces a temporal deployment of attention and optimize temporal preparation. The second objective is to show that when the mental effort is maintained for a long time, it may lead to mental fatigue. We try to find psychological, neurological and physiological markers of mental effort for a better characterization of the mental fatigue described in everyday life and neurological diseases. In the first study, we showed that MT optimized temporal expectancies for shortest foreperiods “FPs” (250/280ms in intrinsic alertness and 650ms in extrinsic task). Strengthened effective connectivity between the right anterior insula (AI) and anterior cingulate (ACC), AI and dorsolateral prefrontal cortex (DLPFC) during intrinsic alertness and between the DLPFC and ACC, during extrinsic alertness was observed. The second study showed after MT, increased reaction times by the end of the session only in intrinsic alertness (250/280ms FPs) associated with decreased connectivity between AI-ACC and AI-DLPFC. We suggest that FP and MT may play a crucial role in temporal deployment of attention and would constitute psychological and neurological markers of mental effort or fatigue, notably through AI-ACC-DLPFC network. In the third study, we examined the relation between a physiological component “cortisol” and mental effort. Preliminary results show that the motor imagery task was more demanding in terms of cortisol secretion and was related to increase of hypothalamus and brainstem activity. This study shows that hypothalamus and brainstem may play a major role in the regulation of cortisol secretion in response to cognitively demanding situation
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Nguma, Hugo. "Étude de l'effet de synchronie pour la conception d'IHM adaptatives : Effet sur la vigilance, la charge mentale, la conscience de la situation et les performances." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ2007.
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Le domaine des Interactions Homme Machine (IHM) s’intéresse dès ses débuts aux différences interindividuelles et à leurs effets sur la performance. Pour répondre aux difficultés posées par ces variabilités pour la conception, 3 grands types d’IHM sont catégorisés :Les IHM adaptées, les IHM adaptables et les IHM adaptatives prenant en compte des particularités propres à l’utilisateur courant.L’implémentation de cette dernière catégorie nécessite le concours de plusieurs disciplines pour déterminer les facteurs à prendre en considération par rapport à la tâche et à l’activité en cours et proposer des modèles utilisateurs de l’état de l’opérateur afin de modifier l’IHM. Dans ce travail de thèse, nous nous sommes intéressés aux variabilités inter et intra-individuelles grâce à l'étude des effets de synchronie (moment de la journée optimal ou non en fonction du chronotype de l'individu considéré (matinal/intermédiaire/vespéral)) et du niveau de vigilance sur les performances. Les effets de synchronie ont été étudiés dans des domaines comme le marketing, mais sont peu étudiés en IHM. Une expérimentation a été réalisée auprès de 62 participants et a permis d’étudier les effets du moment de la journée, du chronotype et de la difficulté de la tâche sur les performances à une tâche de simulation de navigation. Les résultats obtenus montrent des effets significatifs de ces facteurs sur la performance et l'état fonctionnel de l'opérateur avec des sensibilités différentes en fonction de l'indicateur considéré. Cela permet d'envisager des possibilités de recommandations pour la prise en considération de ces facteurs lors de la conception d'IHM adaptativesThe field of Human-Machine Interaction (HMI) has been interested in interindividual differences and its effect on performance since the beginning. To address the challenges posed by these variabilities in the design process, 3 types of HMI have been categorized:User-adapted HMIs, adaptable HMIs, and adaptive HMIs taking into account the current user’s characteristics. The implementation of this last category needs the support of several disciplines in order to determine the factors to take into consideration in relation to the current task and activity and products user models of the operator’s state so as to adjust the HMI accordingly. In this thesis, we were interested in interindividual and intraindividual variabilities via the study of synchrony effects (optimal or suboptimal time of day according to the considered individual’s chronotype (morning type/intermediary type/evening type)) and the level of alertness on performances. The synchrony effects have been studied in other fields such as marketing but are very under-studied in the HMI field. An experiment has been conducted with 62 participants in order to study the effect of time-of-day, chronotype and task difficulty on performances during a navigational simulation task. The results show significative effect of these factors on performance and operator’s functional state with different sensibilities depending on the indicator used, which allows possible recommendations on the consideration of those factors in adaptive HMI design
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Subandono, Subandono. "Institutions, croissance économique et entrepreneuriat : causes et conséquences des activités entrepreneuriales sur le développement économique des régions indonésiennes." Thesis, Paris 1, 2015. http://www.theses.fr/2015PA010041.
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Le but de cette thèse est d'examiner les causes et les conséquences des activités productives des entrepreneurs. Cette étude utilise la base de données sur les régions d'Indonésie pour mettre à l'épreuve des faits nos hypothèses. Le premier chapitre scrute le rôle de l'entrepreneur dans la dynamique du marché du travail. Son originalité est d'introduire la structure du chômage et de travailleur indépendant pour expliquer la relation entre l'entrepreneuriat et le chômage. Le deuxième chapitre cherche à renouveler le raisonnement sur les relations entre les institutions et l'entrepreneuriat. La particularité de cette étude est d'expliquer ces relations au travers de l'ontologie d'Aristote de la contingence et de la prudence. Le troisième chapitre étudie les conséquences de la diversité culturelle sur l'entrepreneuriat. Nous proposons que la diversité culturelle n'influence pas seulement la compétence des individus à découvrir des opportunités, mais qu'elle se trouve également à l'origine de ces opportunités. Le quatrième chapitre étudie les effets des activités productives des entrepreneurs sur la croissance économique. Nous proposons quatre types de modèles économiques: Innovation-économie managériale, innovation-économie entrepreneuriale, imitation-économie managériale et imitation-économie entrepreneuriale. Le cinquième chapitre a pour but de comprendre les conséquences de l'entrepreneuriat sur le processus de la convergence économique. Nous proposons que l'égalisation du capital entrepreneurial à la période initiale soit un facteur nécessaire à la formation de convergence clubThis dissertation aims to examine the causes and consequences of entrepreneurial productive activities. This study makes use Indonesian cross-region database to investigate empirically our hypotheses. The first chapter observes the role of entrepreneurship in the dynamic of the labor markets. The value of this chapter is to consider the structure of unemployment and self-employment to uncover the entrepreneurship-unemployment relationships. The second chapter seeks to renew the explanation of the relationships between institutions and entrepreneurship. The originality is to explain this relationship through Aristotle's ontology of contingency and prudence. The third chapter investigates the consequences of cultural diversity on entrepreneurship. We propose that cultural heterogeneity not only influences the ability to discover profit opportunities, but it also is the origin of these opportunities. The fourth chapter studies the effect of entrepreneurial productive activities of economic growth. The novelty of this chapter is to propose that a country's model of economic growth may fall into four possible economic models: innovation-managed economy or innovationentrepreneurial economy and imitation-managed economy or imitation-entrepreneurial economy. The fifth chapter aims to understand the consequences of entrepreneurship on the process of convergence. We propose that the equalization of entrepreneurial capital at the initial period is a conditioning factor of convergence club formation and different types of entrepreneurship based on technology intensity matters for explaining the process of catch-up
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Indlekofer, Friedrich J., Michaela Piechatzek, Marcel Daamen, Christoph Glasmacher, Roselind Lieb, Hildegard Pfister, Oliver Tucha, Hans-Ulrich Wittchen, and Christian G. Schütz. "Reduced memory and attention performance in a population-based sample of young adults with a moderate lifetime use of cannabis, ecstasy and alcohol." Technische Universität Dresden, 2009. https://tud.qucosa.de/id/qucosa%3A26699.
Full textAbstract:
Regular use of illegal drugs is suspected to cause cognitive impairments. Two substances have received heightened attention: 3,4-methylenedioxymethamphetamine (MDMA or ‘ecstasy’) and δ-9-tetrahydrocannabinol (THC or ‘cannabis’). Preclinical evidence, as well as human studies examining regular ecstasy consumers, indicated that ecstasy use may have negative effects on learning, verbal memory and complex attentional functions. Cannabis has also been linked to symptoms of inattention and deficits in learning and memory. Most of the published studies in this field of research recruited participants by means of newspaper advertisements or by using word-of-mouth strategies. Because participants were usually aware that their drug use was critical to the research design, this awareness may have caused selection bias or created expectation effects. Focussing on attention and memory, this study aimed to assess cognitive functioning in a community-based representative sample that was derived from a large-scale epidemiological study. Available data concerning drug use history allowed sampling of subjects with varying degrees of lifetime drug experiences. Cognitive functioning was examined in 284 young participants, between 22 and 34 years. In general, their lifetime drug experience was moderate. Participants completed a neuropsychological test battery, including measures for verbal learning, memory and various attentional functions. Linear regression analysis was performed to investigate the relationship between cognitive functioning and lifetime experience of drug use. Ecstasy and cannabis use were significantly related to poorer episodic memory function in a dose-related manner. For attentional measures, decrements of small effect sizes were found. Error measures in tonic and phasic alertness tasks, selective attention task and vigilance showed small but significant effects, suggesting a stronger tendency to experience lapses of attention. No indication for differences in reaction time was found. The results are consistent with decrements of memory and attentional performance described in previous studies. These effects are relatively small; however, it must be kept in mind that this study focussed on assessing young adults with moderate drug use from a population-based study.
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Methfessel, Isabel [Verfasser], Jürgen L. [Akademischer Betreuer] Müller, Andrea [Gutachter] Antal, and Martin [Gutachter] Oppermann. "Ist sexuelles Interesse messbar? Hämodynamische und behaviorale Korrelate sexueller Aufmerksamkeit bei heterosexuellen Männern in Bezug auf erwachsene und kindliche sexuelle Stimuli : Neurofunctional correlates of sexual alertness of heterosexual males / Isabel Methfessel ; Gutachter: Andrea Antal, Martin Oppermann ; Betreuer: Jürgen L. Müller." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/115095969X/34.
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Axelsson, John. "Long shifts, short rests and vulnerability to shift work." Doctoral thesis, Stockholm : Department of Psychology, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-453.
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Nee, Mélanie. "Les défauts d'attention dans la survenue de traumatismes non intentionnels." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0212/document.
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L’attention est un prérequis à l’exécution de la majorité des tâches que nous réalisons au quotidien. Si notre niveau d’attention fluctue naturellement au cours de la journée, de nombreux facteurs peuvent également altérer notre niveau de vigilance (p. ex. alcool, médicaments) ou détourner notre attention (p. ex. téléphone, pensées) et, dès lors, nous exposer à un risque d’accident. En accidentologie routière, les défauts d’attention sont devenus un enjeu de préoccupation majeur, mais des questions demeurent en suspens. Et qu’en est-il des autres traumatismes non intentionnels ? L’objectif de ce travail de thèse était d’étudier le rôle des défauts d’attention dans la survenue de traumatismes non intentionnels. Il s’agissait d’explorer des questions épidémiologiques restées en suspens en accidentologie routière tout en élargissant la problématique à ces accidents moins connus que sont les accidents de la vie courante (AcVC). Pour ce faire, trois axes ont été explorés. Le premier a consisté à étudier le lien entre consommation de médicaments et risque d’accident de la route chez les piétons en s’appuyant sur l’appariement des données sur les remboursements de médicaments de l’Assurance Maladie avec celles sur les accidents de la circulation recueillies par les forces de l’ordre. Dans un second temps, nous nous sommes intéressés à la problématique des différents types de distraction au volant. Cette seconde partie a reposé sur les données d’une étude menée au CHU de Bordeaux. Enfin, un dernier axe a consisté à étudier le rôle des défauts d’attention dans la survenue des AcVC en s’appuyant sur les données d’une cohorte prospective et en ligne sur les AcVC. Dans cette dernière étude, les défauts d’attention ont été étudiés sous l’angle du mind-wandering en tant que trait mesuré par le biais d’un questionnaire ainsi que par l’implémentation de trois tests neuropsychologiques en ligne. Plusieurs classes de médicaments, dont les benzodiazépines, étaient associées à une augmentation du risque d’accident chez les piétons. Dans l’étude sur la distraction au volant, la distraction visuelle a été identifiée comme étant celle qui présentait le plus de risque. Enfin, si aucun lien n’a été trouvé entre les mesures aux tests neuropsychologiques et le risque d’accident de la vie courante, le mind-wandering trait a été associé à une augmentation du risque d’accident de type sports, loisirs et déplacements. Ce travail fournit un éclairage essentiel sur des questions restées jusqu’ici inexplorées. Au-delà des conducteurs et du risque routier, nos résultats indiquent que les défauts d’attention pourraient également présenter un risque pour les piétons ainsi que pour la survenue d’autres accidents du quotidien. Dans les années à venir, la part des défauts d’attention dans la survenue de traumatismes devrait encore croître du fait notamment de l’utilisation croissante des nouvelles technologies dans notre quotidien. Par conséquent, mieux comprendre le rôle de ces défauts d’attention dans la survenue de traumatismes non intentionnels est plus que jamais essentielAttention is a complex process that is required in almost all our daily activities. Beyond its natural fluctuation during the day, our level of attention is also influenced by a large range of factors that can diminish our level of alertness (e.g. medicines, alcohol use) or divert our attention (e.g. mobile phone, thoughts) thus exposing us to the occurrence of unintentional injuries. In road traffic safety, attention failures have been identified as a major cause of concern but questions remain unsolved. What about attentional failures in the occurrence of daily-life injuries ? The aim of this thesis was to explore the role of attention failures on the risk of unintentional injuries. The idea was to explore epidemiological issues that remained unresolved in road traffic injuries while extending the problematic to those lesser-known injuries that are Home and Leisure Injuries (HLIs). To that end, this thesis was divided in three parts. First, we investigated the association between medicine use and the risk of road traffic injuries among pedestrians. To do that, we used data on road traffic crashes collected by the French police forces matching with data on reimbursed medicine from the French Health insurance. In a second part, we were interested in several types of driving distractions on the risk of road traffic crashes using data from a sample of road users interviewed at the Bordeaux University Hospital. The third and final part was to study the role of attentional failures on the occurrence of HLIs and was based on data from a prospective and online cohort on HLIs. Attentional failures were studied from the perspective of mind-wandering as a trait measured through a questionnaire and also the implementation of three online neuropsychological tests. Several medicine classes, including benzodiazepines, were associated with an increased risk of being involved in a road traffic crash as a pedestrian. In the study on distracted driving, the higher risk was found for visual distraction. Finally, whereas neuropsychological test scores were not associated with a higher risk of HLI, mind-wandering trait was associated with a higher risk of sport, leisure and moving-related injuries. This work provides essential insights into issues that have remained unexplored to date. Beyond the drivers and road risk, our results indicate that attentional failures could also present a risk for pedestrians as well as for the occurrence of other everyday injuries. In years, to come, the share of attentional failures in the occurrence of injuries is expected to further increase, particularly due to the increasing use of new technologies in our daily live. Therefore, a better understanding of the role of these attentional failures in the occurrence of unintentional injuries is more than ever essential
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Eugene, Nicole Christina. "POTENT SLEEP: THE CULTURAL POLITICS OF SLEEP." Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1151208257.
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Mühlhan, Markus, Michael Marxen, Julia Landsiedel, Hagen Malberg, and Sebastian Zaunseder. "The effect of body posture on cognitive performance: a question of sleep quality." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-147476.
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Nearly all functional magnetic resonance imaging (fMRI) studies are conducted in the supine body posture, which has been discussed as a potential confounder of such examinations. The literature suggests that cognitive functions, such as problem solving or perception, differ between supine and upright postures. However, the effect of posture on many cognitive functions is still unknown. Therefore, the aim of the present study was to investigate the effects of body posture (supine vs. sitting) on one of the most frequently used paradigms in the cognitive sciences: the N-back working memory paradigm. Twenty-two subjects were investigated in a randomized within-subject design. Subjects performed the N-back task on two consecutive days in either the supine or the upright posture. Subjective sleep quality and chronic stress were recorded as covariates. Furthermore, changes in mood dimensions and heart rate variability (HRV) were assessed during the experiment. Results indicate that the quality of sleep strongly affects reaction times when subjects performed a working memory task in a supine posture. These effects, however, could not be observed in the sitting position. The findings can be explained by HRV parameters that indicated differences in autonomic regulation in the upright vs. the supine posture. The finding is of particular relevance for fMRI group comparisons when group differences in sleep quality cannot be ruled out.
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Vezard, Laurent. "Réduction de dimension en apprentissage supervisé : applications à l’étude de l’activité cérébrale." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR15005/document.
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L'objectif de ce travail est de développer une méthode capable de déterminer automatiquement l'état de vigilance chez l'humain. Les applications envisageables sont multiples. Une telle méthode permettrait par exemple de détecter automatiquement toute modification de l'état de vigilance chez des personnes qui doivent rester dans un état de vigilance élevée (par exemple, les pilotes ou les personnels médicaux).Dans ce travail, les signaux électroencéphalographiques (EEG) de 58 sujets dans deux états de vigilance distincts (état de vigilance haut et bas) ont été recueillis à l'aide d'un casque à 58 électrodes posant ainsi un problème de classification binaire. Afin d'envisager une utilisation de ces travaux sur une application du monde réel, il est nécessaire de construire une méthode de prédiction qui ne nécessite qu'un faible nombre de capteurs (électrodes) afin de limiter le temps de pose du casque à électrodes ainsi que son coût. Au cours de ces travaux de thèse, plusieurs approches ont été développées. Une première approche propose d'utiliser un pré-traitement des signaux EEG basé sur l'utilisation d'une décomposition en ondelettes discrète des signaux EEG afin d'extraire les contributions de chaque fréquence dans le signal. Une régression linéaire est alors effectuée sur les contributions de certaines de ces fréquences et la pente de cette régression est conservée. Un algorithme génétique est utilisé afin d'optimiser le choix des fréquences sur lesquelles la régression est réalisée. De plus, cet algorithme génétique permet la sélection d'une unique électrode.Une seconde approche est basée sur l'utilisation du Common Spatial Pattern (CSP). Cette méthode permet de définir des combinaisons linéaires des variables initiales afin d'obtenir des signaux synthétiques utiles pour la tâche de classification. Dans ce travail, un algorithme génétique ainsi que des méthodes de recherche séquentielle ont été proposés afin de sélectionner un sous groupes d'électrodes à conserver lors du calcul du CSP.Enfin, un algorithme de CSP parcimonieux basé sur l'utilisation des travaux existant sur l'analyse en composantes principales parcimonieuse a été développé.Les résultats de chacune des approches sont détaillés et comparés. Ces travaux ont aboutit sur l'obtention d'un modèle permettant de prédire de manière rapide et fiable l'état de vigilance d'un nouvel individuThe aim of this work is to develop a method able to automatically determine the alertness state of humans. Such a task is relevant to diverse domains, where a person is expected or required to be in a particular state. For instance, pilots, security personnel or medical personnel are expected to be in a highly alert state, and this method could help to confirm this or detect possible problems. In this work, electroencephalographic data (EEG) of 58 subjects in two distinct vigilance states (state of high and low alertness) were collected via a cap with $58$ electrodes. Thus, a binary classification problem is considered. In order to use of this work on a real-world applications, it is necessary to build a prediction method that requires only a small number of sensors (electrodes) in order to minimize the time needed by the cap installation and the cap cost. During this thesis, several approaches have been developed. A first approach involves use of a pre-processing method for EEG signals based on the use of a discrete wavelet decomposition in order to extract the energy of each frequency in the signal. Then, a linear regression is performed on the energies of some of these frequencies and the slope of this regression is retained. A genetic algorithm (GA) is used to optimize the selection of frequencies on which the regression is performed. Moreover, the GA is used to select a single electrode .A second approach is based on the use of the Common Spatial Pattern method (CSP). This method allows to define linear combinations of the original variables to obtain useful synthetic signals for the task classification. In this work, a GA and a sequential search method have been proposed to select a subset of electrode which are keep in the CSP calculation.Finally, a sparse CSP algorithm, based on the use of existing work in the sparse principal component analysis, was developed.The results of the different approaches are detailed and compared. This work allows us to obtaining a reliable model to obtain fast prediction of the alertness of a new individual