| 1. |
- Abrahamsen, Annbjørg, et al.
(författare)
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Sleep, Sleepiness, and Fatigue on Board Faroese Fishing Vessels
- 2022
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Ingår i: Nature and Science of Sleep. - 1179-1608. ; 14, s. 347-362
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Faroese fishers have four times more accidents than workers on land. The aim was to understand fishers’ fatigue better and how their work and sleep patterns influenced their sleepiness levels and cognitive performance.Materials and Methods: A total of 157 Faroese fishers wore wrist-worn actigraphs at sea and one week on land and filled in sleep and sleepiness diaries during the trip. Furthermore, a 3-minute simple reaction time (SRT) test was completed at the beginning and end of the trip. The ship’s movement and noise were also logged. The actiwatch results were analysed with mixed methods repeated measures. The sleepiness registrations and performance on the SRT-test were analysed with paired t-test. The ship movements (Pitch and roll) were divided into approximately three same-sized groups (lowest 1/3, medium 1/3, and highest 1/3) and compared against the Karolinska Sleepiness Scores (KSS ranging from 1– 9) ≥ 7 and physical tiredness (ranging from 1– 9) scores ≥ 7. Chi-square tests were used to determine the significance of these differences. Mean sleepiness scores at sea, and the proportion of sleepiness scores ≥ 7 were calculated, as well as sleepiness scores as a function of the time of day.Results: While at sea, fishers had more split sleep, slept less, and had lower sleep efficiency than onshore. Sleepiness was higher at the end of the trip, and cognitive decline was found. The number of major lapses was higher at the end of the trip, but with no significant difference between the median reaction times.Conclusion: The crew on-board the freezer longliner, who worked 8– 8 shifts, slept the most, had the longest continuous sleep periods, the highest sleep efficiency, the lowest sleepiness levels, and the highest noise exposure during their time off.
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| 2. |
- Brandao, Luiz Eduardo M., et al.
(författare)
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Social Jetlag Changes During the COVID-19 Pandemic as a Predictor of Insomnia - A Multi-National Survey Study
- 2021
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Ingår i: Nature and Science of Sleep. - : Dove Medical Press. - 1179-1608. ; 13, s. 1711-1722
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Lifestyle and work habits have been drastically altered by restrictions due to the COVID-19 pandemic. Whether the associated changes in sleep timing modulate the risk of suffering from symptoms of insomnia, the most prevalent sleep disorder, is however incompletely understood. Here, we evaluate the association between the early pandemic-associated change in 1) the magnitude of social jetlag (SJL) - ie, the difference between sleep timing on working vs free days - and 2) symptoms of insomnia.Patients and Methods: A total of 14,968 anonymous participants (mean age: 40 years; 64% females) responded to a standardized internet-based survey distributed across 14 countries. Using logistic multivariate regression, we examined the association between the degree of social jetlag and symptoms of insomnia, controlling for important confounders like social restriction extension, country specific COVID-19 severity and psychological distress, for example.Results: In response to the pandemic, participants reported later sleep timing, especially during workdays. Most participants (46%) exhibited a reduction in their SJL, whereas 20% increased it; and 34% reported no change in SJL. Notably, we found that both increased and decreased SJL, as a result of the COVID-19 pandemic, were associated with later sleep midpoint (indicating a later chronotype) as well as more recurrent and moderate-to-severe symptoms of insomnia (about 23-54% higher odds ratio than subjects with unchanged SJL). Primarily those with reduced SJL shifted their bedtimes to a later timepoint, compared with those without changes in SJL.Conclusion: Our findings offer important insights into how self-reported changes to the stability of sleep/wake timing, as reflected by changes in SJL, can be a critical marker of the risk of experiencing insomnia-related symptoms - even when individuals manage to reduce their social jetlag. These findings emphasize the clinical importance of analyzing sleep-wake regularity.
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| 3. |
- Burdakov, S. F., et al.
(författare)
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Robust control of nonlinear mechanical systems using linear feedback
- 1999
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Ingår i: Automation and remote control. - NEW YORK, NY, USA. - 0005-1179 .- 1608-3032. ; 60:11, s. 1577-1586
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Tidskriftsartikel (refereegranskat)abstract
- A linear law of control of a mechanical system through drives nonrigidly connected to the system is suggested. The law involves measurement of the positions of links and angular velocities of drives and features a nonminimal-phase character of the transfer function. Stability conditions that remain valid with an increase in the gain are set zip. Results of the numerical modeling in solving problems of positioning anal tracking for robots (manipulators) are described.
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| 4. |
- Davidson, Per, et al.
(författare)
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Does sleep selectively strengthen certain memories over others based on emotion and perceived future relevance?
- 2021
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Ingår i: Nature and Science of Sleep. - : Dove Medical Press Ltd.. - 1179-1608. ; 13, s. 1257-1306
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Tidskriftsartikel (refereegranskat)abstract
- Sleep has been found to have a beneficial effect on memory consolidation. It has furthermore frequently been suggested that sleep does not strengthen all memories equally. The first aim of this review paper was to examine whether sleep selectively strengthens emotional declarative memories more than neutral ones. We examined this first by reviewing the literature focusing on sleep/wake contrasts, and then the literature on whether any specific factors during sleep preferentially benefit emotional memories, with a special focus on the often-suggested claim that rapid eye movement sleep primarily consolidates emotional memories. A second aim was to examine if sleep preferentially benefits memories based on other cues of future relevance such as reward, test-expectancy or different instructions during encoding. Once again, we first focused on studies comparing sleep and wake groups, and then on studies examining the contributions of specific factors during sleep (for each future relevance paradigm, respectively). The review revealed that although some support exists that sleep is more beneficial for certain kinds of memories based on emotion or other cues of future relevance, the majority of studies does not support such an effect. Regarding specific factors during sleep, our review revealed that no sleep variable has reliably been found to be specifically associated with the consolidation of certain kinds of memories over others based on emotion or other cues of future relevance.
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| 5. |
- Davidson, Per, et al.
(författare)
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Does sleep selectively strengthen certain memories over others based on emotion and perceived future relevance?
- 2021
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Ingår i: Nature and Science of Sleep. - : Dove Medical Press Ltd.. - 1179-1608. ; 13, s. 1257-1306
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Forskningsöversikt (refereegranskat)abstract
- Sleep has been found to have a beneficial effect on memory consolidation. It has furthermore frequently been suggested that sleep does not strengthen all memories equally. The first aim of this review paper was to examine whether sleep selectively strengthens emotional declarative memories more than neutral ones. We examined this first by reviewing the literature focusing on sleep/wake contrasts, and then the literature on whether any specific factors during sleep preferentially benefit emotional memories, with a special focus on the often-suggested claim that rapid eye movement sleep primarily consolidates emotional memories. A second aim was to examine if sleep preferentially benefits memories based on other cues of future relevance such as reward, test-expectancy or different instructions during encoding. Once again, we first focused on studies comparing sleep and wake groups, and then on studies examining the contributions of specific factors during sleep (for each future relevance paradigm, respectively). The review revealed that although some support exists that sleep is more beneficial for certain kinds of memories based on emotion or other cues of future relevance, the majority of studies does not support such an effect. Regarding specific factors during sleep, our review revealed that no sleep variable has reliably been found to be specifically associated with the consolidation of certain kinds of memories over others based on emotion or other cues of future relevance.
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| 6. |
- Gholami, Omid, 1979-, et al.
(författare)
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Heuristic Algorithms to Maximize Revenue and the Number of Jobs Processed on Parallel Machines
- 2019
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Ingår i: Automation and remote control. - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0005-1179 .- 1608-3032. ; 80:2, s. 297-316
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Tidskriftsartikel (refereegranskat)abstract
- A set of jobs has to be processed on parallel machines. For each job, there are given a release time and a due date and the job must be processed no later than its due date. If the job will be completed no later than the given due date, a benefit will be earned. Otherwise, this job will be rejected and the benefit will be discarded. The criterion under consideration is to maximize the weighted sum of the benefits and the number of jobs processed in time. Some properties of the objective function are found which allow to construct a optimal schedule. We develop a simulated annealing algorithm, a tabu search algorithm, and a genetic algorithm for solving this problem. The developed algorithms were tested on moderate and large instances with up to 500 jobs and 50 machines. Some recommendations are given showing how to use the obtained results and developed algorithms in production planning.
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| 7. |
- Hedström, Anna Karin, et al.
(författare)
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Association Between Insomnia And Mortality Is Only Evident Among Long Sleepers
- 2019
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Ingår i: Nature and Science of Sleep. - 1179-1608. ; 11, s. 333-342
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous studies investigating the relationship between insomnia and mortality have been inconsistent. Purpose: We aimed to assess whether nocturnal insomnia symptoms and non-restorative sleep are associated with all-cause mortality and whether they modify the associations between short and long sleep duration and all-cause mortality. Patients and methods: The present report is based on a prospective cohort study of 39,139 participants with a mean follow-up time of 19.6 years. Cox proportional hazard models with attained age as timescale were used to estimate overall mortality hazard ratios (HRs) with 95% confidence intervals (CI) for different categories of sleep duration and insomnia symptoms. Results: Both difficulty initiating sleep and daytime sleepiness were independently associated with increased mortality among those with sleep duration of 9 hrs or more (HR 1.51, 95% CI 1.11-2.07 and HR 1.37, 95% CI 1.03-1.82). Mortality increased with increasing severity of difficulties initiating sleep (p for trend 0.04) and daytime sleepiness (p for trend 0.01) among the long sleepers. None of the insomnia symptoms were associated with mortality among those who reported sleep duration of 8 hrs or less. Conclusion: Long sleep in combination with difficulties initiating sleep and daytime sleepiness, possibly due to psychiatric or physical disorders, was thus associated with increased mortality, whereas long sleep without difficulties falling asleep or daytime sleepiness was not associated with mortality. Our study emphasizes the need to take nocturnal insomnia symptoms and daytime sleepiness into consideration when assessing the influence of sleep duration on mortality. Additional research is needed to elucidate the relationship between long sleep, insomnia and related psychiatric and physical disorders.
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| 8. |
- Härdelin, Goran, et al.
(författare)
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Do Mothers Have Worse Sleep Than Fathers? Sleep Imbalance, Parental Stress, and Relationship Satisfaction in Working Parents
- 2021
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Ingår i: Nature and Science of Sleep. - 1179-1608. ; 13, s. 1955-1966
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Previous research indicates that mothers take a larger responsibility for child care during the night and that they have more disturbed sleep than fathers. The purpose of this study was to determine whether such a sleep imbalance exists in working parents of young children, and the extent to which it depends on the way sleep is measured. The study also examined whether imbalanced sleep between parents predicts parental stress and relationship satisfaction.Methods: Sleep was measured for seven consecutive days in 60 parenting couples (average age of the youngest child: 3.3 years ± SD 2.5 years). Actigraphs were worn across the week, and ratings of sleep, parental stress, and relationship satisfaction were made daily.Results: Mothers perceived their sleep quality as worse (b= − 0.38 scale units, p< 0.001), with more wake periods (b= +0.96 awakenings, p< 0.001) but with longer sleep duration (b= +32.4 min, p< 0.01) than fathers. Actigraphy data confirmed that mothers slept longer than fathers (b= +28.03 min, p< 0.001), but no significant differences were found for wake time, number of awakenings or who woke up first during shared awakenings. Furthermore, there was no difference in whether mothers and fathers slept sufficiently. The level of sleep imbalance between parents did not predict parental stress. A larger imbalance in subjective sleep sufficiency predicted decreased relationship satisfaction for fathers (b= − 0.13 scale units, p< 0.01) but increased relationship satisfaction for mothers (b= 0.14 scale units, p< 0.05). No other sleep imbalance measures predicted relationship satisfaction.Conclusion: Our findings are in line with previous research on sleep in men and women in general, with longer sleep and subjective reports of sleep disturbances in women, rather than previous research on sleep in parents of young children. Thus, we found no evidence of a sleep imbalance when both parents have similar working responsibilities.
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| 9. |
- Krasheninnikov, Pavel V., et al.
(författare)
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Parameter Estimation for the Resulting Logical Channel Formed by Minimizing Channel Switching
- 2019
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Ingår i: Automation and remote control. - : Springer. - 0005-1179 .- 1608-3032. ; 80:2, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- We propose a method for calculating the parameters of the resulting discrete channel for secondary users in cognitive radio systems formed by the algorithm for minimizing channel switchings. The availability of channel slots is defined by a simple Markov chain. We obtain mathematical expressions for determining the transition probabilities of a graph reduced to two states for any number of primary channels.
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| 10. |
- Ljung, Lennart
(författare)
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On Convexification of System Identification Criteria
- 2019
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Ingår i: Automation and remote control. - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0005-1179 .- 1608-3032. ; 80:9, s. 1591-1606
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Tidskriftsartikel (refereegranskat)abstract
- System Identification is about estimating models of dynamical systems from measured input-output data. Its traditional foundation is basic statistical techniques, such as maximum likelihood estimation and asymptotic analysis of bias and variance and the like. Maximum likelihood estimation relies on minimization of criterion functions that typically are non-convex, and may cause numerical search problems and estimates trapped in local minima. Recent interest in identification algorithms has focused on techniques that are centered around convex formulations. This is partly the result of developments in semidefinite programming, machine learning and statistical learning theory. The development concerns issues of regular-ization for sparsity and for better tuned bias/variance trade-offs. It also involves the use of subspace methods as well as nuclear norms as proxies to rank constraints. A special approach is to look for difference-of-convex programming (DCP) formulations, in case a pure convex criterion is not found. Other techniques are based on Lagrangian relaxation and contraction theory. A quite different route to convexity is to use algebraic techniques to manipulate the model parameterizations. This article will illustrate all this recent development.
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