| 1. |
- Hogenkamp, Pleunie S, et al.
(författare)
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Sweet taste perception not altered after acute sleep deprivation in healthy young men.
- 2013
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Ingår i: Somnologie : Schlafforschung und Schlafmedizin = Somnology : sleep research and sleep medicine. - : Springer Science and Business Media LLC. - 1432-9123 .- 1439-054X. ; 17:2, s. 111-114
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Tidskriftsartikel (refereegranskat)abstract
- We hypothesized that acutely sleep-deprived participants would rate ascending concentrations of sucrose as more intense and pleasant, than they would do after one night of normal sleep. Such a finding would offer a potential mechanism through which acute sleep loss could promote overeating in humans.
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| 2. |
- Karimi, Mahssa, et al.
(författare)
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Is a polysomnographic recording prior to MSLT worth the effort? : Lohnt sich eine Polysomnographie vor dem MSLT?
- 2011
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Ingår i: Somnologie - Schlafforschung und Schlafmedizin. - : Springer Science and Business Media LLC. - 1432-9123 .- 1439-054X. ; 15:4, s. 239-242
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Tidskriftsartikel (refereegranskat)abstract
- Objective. It was recently proposed that polysomnography (PSG) may be replaced by actigraphy in order to obtain long-term sleep time prior to the multiple sleep latency test (MSLT). Polysomnography is used to assess sleep time and to detect and classify underlying sleep pathology. In the following article, the contribution of PSG to the diagnostic outcome of the MSLT is discussed.Methods. MSLT referrals (n = 81) with in-home polysomnography from the neurology (n = 39, 23 women, 37 (±13) years) and pulmonary medicine (n = 42, 20 women, 41 (±14) years) departments were analyzed. The diagnostic outcomes of the PSG and MSLT were examined.Results. Median total sleep time prior to MSLT was 362 (range, 156–530) min. Sleep apnea (respiratory disturbance index > 15/h and > 30/h) was diagnosed in 21 and 19 patients, respectively. Periodic limb movements (PLM) were identified in 5 patients; 3 of these had a PLM arousal index > 5/h. Sleep onset REM (SOREM) was detected during PSG in 5 patients; 4 of these also had SOREM in the MSLT.Conclusion. PSG combined with MSLT was found to improve diagnostic outcome and is highly useful for recognition of sleep-related pathology. Various sleep disorders remain undetected if ACT alone is used prior to MSLT procedures.
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| 3. |
- Åkerstedt, Torbjörn, et al.
(författare)
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Individual validation of model predictions of sleepiness and sleep hours
- 2007
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Ingår i: Somnologie. - : Springer Science and Business Media LLC. ; 11, s. 169-174
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Several mathematical models for prediction of sleepiness have been developed. Few validations on individual levels are available.BackgroundThe present study was designed to provide validation on the individual level of predictions using the Three Process-Model of alertness regulation. Model predictions of sleep timing were also tested.MethodSixteen shift workers participated in the study. Ratings of sleepiness were made every 2h across three shifts. The model was used to predict empirical ratings using as input only information of beginning and end of work shifts, as well as using information on sleep from actigraphs (in a separate analysis).ResultsThe prediction using only information on work shifts correlated r=0.55 (p<0.001) with empirical ratings. Predictions were generally within ±1 confidence interval of the ratings. Adding actigraphy sleep data improved predictions marginally. The model predictions of onset and offset of sleep were generally close to the target.ConclusionIt was concluded that model predictions have a rather high validity both with respect to sleepiness and to sleep timing. It is probable that other information on individual differences will further improve predictability.
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| 4. |
- Åkerstedt, Torbjörn, et al.
(författare)
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Subjective and objective quality of sleep : [Subjektive und objektive Schlafqualität]
- 2008
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Ingår i: Somnologie. - : Springer Science and Business Media LLC. - 1432-9123 .- 1439-054X. ; 12, s. 104-109
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Relatively few studies have tried to relate subjective sleep quality to objective sleep parameters and most have been carried out in laboratory settings and often with patients and usually only for a single night. The present study used a group of 33 subjects who had sleep polysomnographically recorded in their homes for three nights during a period of several weeks. First a multiple regression analysis was carried out for each night with a 4-item sleep quality index as the dependent variable and conventional sleep parameters as predictors. This yielded a significant beta value for percent Stage O for each of the three nights. Sleep efficiency showed a significant correlation with sleep quality for two nights but did not enter the regression. When the night with the best and poorest sleep were compared, the only significant variable became percent SWS. It was suggested that the differing results may have been due to the large age span confusing SWS/quality correlations.
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| 5. |
- Andersson, Daniel, et al.
(författare)
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A maximum principle for SDEs of mean-field type
- 2011
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Ingår i: Applied mathematics and optimization. - : Springer Science and Business Media LLC. - 0095-4616 .- 1432-0606. ; 63:3, s. 341-356
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Tidskriftsartikel (refereegranskat)abstract
- We study the optimal control of a stochastic differential equation (SDE) of mean-field type, where the coefficients are allowed to depend on some functional of the law as well as the state of the process. Moreover the cost functional is also of mean-field type, which makes the control problem time inconsistent in the sense that the Bellman optimality principle does not hold. Under the assumption of a convex action space a maximum principle of local form is derived, specifying the necessary conditions for optimality. These are also shown to be sufficient under additional assumptions. This maximum principle differs from the classical one, where the adjoint equation is a linear backward SDE, since here the adjoint equation turns out to be a linear mean-field backward SDE. As an illustration, we apply the result to the mean-variance portfolio selection problem.
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| 6. |
- Schöier, Fredrik, 1969, et al.
(författare)
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The abundance of HCN in the circumstellar envelopes of AGB stars different chemical type
- 2013
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 550
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Tidskriftsartikel (refereegranskat)abstract
- Aims. A multi-transition survey of HCN (sub-) millimeter line emission from a large sample of asymptotic giant branch (AGB) stars of different chemical type is presented. The data are analysed and circumstellar HCN abundances are estimated. The sample stars span a large range of properties such as mass-loss rate and photospheric C/O-ratio. The analysis of the new data allows for more accurate estimates of the circumstellar HCN abundances and puts new constraints on chemical models. Methods. In order to constrain the circumstellar HCN abundance distribution a detailed non-local thermodynamic equilibrium (LTE) excitation analysis, based on the Monte Carlo method, is performed. Effects of line overlaps and radiative excitation from dust grains are included. Results. The median values for the derived abundances of HCN (with respect to H-2) are 3 x 10(-5), 7 x 10(-7) and 10(-7) for carbon stars (25 stars), S-type AGB stars (19 stars) and M-type AGB stars (25 stars), respectively. The estimated sizes of the HCN envelopes are similar to those obtained in the case of SiO for the same sample of sources and agree well with previous results from interferometric observations, when these are available. Conclusions. We find that there is a clear dependence of the derived circumstellar HCN abundance on the C/O-ratio of the star, in that carbon stars have about two orders of magnitude higher abundances than M-type AGB stars, on average. The derived HCN abundances of the S-type AGB stars have a larger spread and typically fall in between those of the two other types, however, slightly closer to the values for the M-type AGB stars. For the M-type stars, the estimated abundances are much higher than what would be expected if HCN is formed in thermal equilibrium. However, the results are also in contrast to predictions from recent non-LTE chemical models, where very little difference is expected in the HCN abundances between the various types of AGB stars.
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