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result(s) for
"Svendsen, K."
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Choosing the unit of measurement counts: The use of oral morphine equivalents in studies of opioid consumption is a useful addition to defined daily doses
by
Borchgrevink, PC
,
Fredheim, O
,
Dale, O
in
Administration, Oral
,
Analgesics
,
Analgesics, Opioid - administration & dosage
2011
Aim: Defined daily dose (DDD) is the most common measurement unit used in drug consumption studies. The DDD for opioids may not reflect their relative clinical potencies. The aim of this study was to explore whether opioid consumption data may be interpreted differently when adding oral morphine equivalent (OMEQ) dose as a measurement unit compared with using DDD.
Methods: The equianalgesic ratio of each opioid relative to morphine was tabulated. Data on opioid consumption expressed in DDD were converted to OMEQs using the equianalgesic ratios. The opioid consumption was compared in three different study settings: clinical data from an opioid switching study, trends within one country and a comparison between countries.
Results: Using DDD, the opioid consumption in Norway between 2004–2008 increased of 6.7%, while the increase was 23.6% using OMEQ. While DDD/1000 inhabitants/day showed that Sweden had the highest consumption of opioids among the Nordic countries, OMEQ/1000 inhabitants/day showed that Denmark had the highest consumption. In the switching study DDD indicated a reduction in analgesic dosing and OMEQ an increase when switching from WHO step II to III.
Conclusion: OMEQ reflects clinical dosing better than DDD, and can give additional insight into opioid consumption when combined with DDD. Using OMEQ can also lead to different conclusions in opioid consumption studies compared with using DDD alone.
Journal Article
Enhanced laser-driven proton acceleration using nanowire targets
by
Permogorov, A.
,
Vallières, S.
,
Chen, Z.
in
639/624/1020/1088
,
639/624/399/1016
,
639/766/1960/1135
2021
Laser-driven proton acceleration is a growing field of interest in the high-power laser community. One of the big challenges related to the most routinely used laser-driven ion acceleration mechanism, Target-Normal Sheath Acceleration (TNSA), is to enhance the laser-to-proton energy transfer such as to maximize the proton kinetic energy and number. A way to achieve this is using nanostructured target surfaces in the laser-matter interaction. In this paper, we show that nanowire structures can increase the maximum proton energy by a factor of two, triple the proton temperature and boost the proton numbers, in a campaign performed on the ultra-high contrast 10 TW laser at the Lund Laser Center (LLC). The optimal nanowire length, generating maximum proton energies around 6 MeV, is around 1–2
μ
m. This nanowire length is sufficient to form well-defined highly-absorptive NW forests and short enough to minimize the energy loss of hot electrons going through the target bulk. Results are further supported by Particle-In-Cell simulations. Systematically analyzing nanowire length, diameter and gap size, we examine the underlying physical mechanisms that are provoking the enhancement of the longitudinal accelerating electric field. The parameter scan analysis shows that optimizing the spatial gap between the nanowires leads to larger enhancement than by the nanowire diameter and length, through increased electron heating.
Journal Article
Quantifying Energy and Mass Fluxes Controlling Godthåbsfjord Freshwater Input in a 5-km Simulation (1991–2012)
2015
Freshwater runoff to fjords with marine-terminating glaciers along the Greenland Ice Sheet margin has an impact on fjord circulation and potentially ice sheet mass balance through increasing heat transport to the glacier front. Here, the authors use the high-resolution (5.5 km) HIRHAM5 regional climate model, allowing high detail in topography and surface types, to estimate freshwater input to Godthåbsfjord in southwest Greenland. Model output is compared to hydrometeorological observations and, while simulated daily variability in temperature and downwelling radiation shows high correlation with observations (typically >0.9), there are biases that impact the results. In particular, overestimated albedo leads to underestimation of melt and runoff at low elevations.
In the model simulation (1991–2012), the ice sheet experiences increasing energy input from the surface turbulent heat flux (up to elevations of 2000 m) and shortwave radiation (at all elevations). Southerly wind anomalies and declining cloudiness due to an increase in atmospheric pressure over north Greenland contribute to increased summer melt. This results in declining surface mass balance (SMB), increasing surface runoff, and upward shift of the equilibrium line altitude.
SMB is reconstructed back to 1890 though regression between simulated SMB and observed temperature and precipitation, with added uncertainty in the period 1890–1952 because of possible inhomogeneity in the precipitation record. SMB as low as in recent years appears to have occurred before, most notably around 1930, 1950, and 1960. While previous low SMBs were mainly caused by low accumulation, those around 1930 and in the 2000s are mainly due to warming.
Journal Article
Collimated x-rays emitted through laser-driven plasma lensing
2025
The Laser wakefield accelerator (LWFA) can be used as a powerful x-ray source, with diverse applications, such as medical imaging, tomography and x-ray absorption spectroscopy for warm dense matter. However, due to the large x-ray divergence, typically on the order of tens of milliradians at full width at half maximum, an effective beam transport to the sample and subsequent detection becomes challenging which limits the signal to noise ratio. By using a laser-plasma lens of high density positioned a few millimetres downstream from the LWFA, x-ray radiation with only a few milliradians divergence is produced. The lens consists of nitrogen gas ionised by the drive laser, within which a wake is excited mainly by the LWFA electron bunch. As the LWFA electrons propagate through this second plasma they generate strong transverse fields, which focuses the beam and produces bright x-rays. In this work, the preliminary parametric study of the x-ray lens radiation is presented.
Journal Article
Are exercise booster sessions effective at preserving exercise-induced effects in people with multiple sclerosis? A randomised controlled trial: results from the MSBOOST trial
by
Højsgaard Chow, H.
,
Taul-Madsen, Laurits
,
Bacher Svendsen, K.
in
Aerobic capacity
,
Exercise booster sessions
,
Muscle strength
2025
In people with multiple sclerosis (PWMS), exercise improves aerobic capacity and muscle strength which are key components of physical function and overall health status. However, the effects diminish after exercise cessation. Therefore, the present study aimed to investigate whether exercise booster sessions (EBS) could preserve the exercise-induced improvements.
Multicentre RCT.
Ninety-four PWMS performed 12 weeks of aerobic-training (AT) or resistance-training (RT) and were subsequently randomised to receive EBS (two sessions every fifth week) (ATboost n = 24, RTboost n = 24) or usual-care (ATuc n = 20, or RTuc n = 26) for 40 weeks. The primary outcome was physical function measured as a composite score of the six-minute walk test (6MWT) and five-time sit-to-stand test (5STS). Secondary outcomes were aerobic capacity and muscle strength.
No between-group difference was observed in the composite score of 6MWT and 5STS (arbitrary unit) between ATboost and RTboost 0.00 [−0.20; 0.20]. No between-group difference was observed for aerobic capacity (mL O2/kg/min) between ATboost and ATuc 1.1 [−1.9; 4.1], although a within-group change was observed for ATboost −1.9 [−4.0; 0.1], but not for ATuc −3.0 [−5.2; −0.8]. No between-group difference was seen for muscle strength (Nm/kg) between RTboost and RTuc −0.04 [−0.36; 0.28]. Also, no within-group change was observed for neither RTboost −0.07 [−0.30; 0.14] nor RTuc −0.04 [−0.27; 0.20].
EBS had no apparent effect on preservation of physical function, aerobic capacity, or muscle strength in PWMS. Muscle strength was preserved regardless of group, whereas only ATboost preserved exercise-induced improvements in aerobic capacity.
Journal Article
Automated Snow Avalanche Monitoring and Alert System Using Distributed Acoustic Sensing in Norway
by
Nilsen, Espen Lauvlund
,
Nyhammer, Finn Kåre
,
Svendsen, Guro K.
in
Accident prevention
,
Acoustics
,
automated avalanche detection
2024
Avalanches present substantial hazard risk in mountainous regions, particularly when avalanches obstruct roads, either hitting vehicles directly or leaving traffic exposed to subsequent avalanches during cycles. Traditional detection methods often are designed to cover only a limited section of a road stretch, hampering effective risk management. This research introduces a novel approach using Distributed Acoustic Sensing (DAS) for avalanche detection. The monitoring site in Northern Norway is known to be frequently impacted by avalanches. Between 2022–2024, we continuously monitored the road for avalanches blocking the traffic. The automated alert system identifies avalanches affecting the road and estimates accumulated snow. The system provides continuous, real-time monitoring with competitive sensitivity and accuracy over large areas (up to 170 km) and for multiple sites on parallel. DAS powered alert system can work unaffected by visual barriers or adverse weather conditions. The system successfully identified 10 road-impacting avalanches (100% detection rate). Our results via DAS align with the previous works and indicate that low frequency part of the signal (<20 Hz) is crucial for detection and size estimation of avalanche events. Alternative fiber installation methods are evaluated for optimal sensitivity to avalanches. Consequently, this study demonstrates its durability and lower maintenance requirements, especially when compared to the high setup costs and coverage limitations of radar systems, or the weather and lighting vulnerabilities of cameras. Furthermore the system can detect vehicles on the road as important supplemental information for search and rescue operations, and thus the authorities can be alerted, thereby playing a vital role in urgent rescue efforts.
Journal Article
Permafrost degradation risk zone assessment using simulation models
2011
In this proof-of-concept study we focus on linking large scale climate and permafrost simulations to small scale engineering projects by bridging the gap between climate and permafrost sciences on the one hand and on the other technical recommendation for adaptation of planned infrastructures to climate change in a region generally underlain by permafrost. We present the current and future state of permafrost in Greenland as modelled numerically with the GIPL model driven by HIRHAM climate projections up to 2080. We develop a concept called Permafrost Thaw Potential (PTP), defined as the potential active layer increase due to climate warming and surface alterations. PTP is then used in a simple risk assessment procedure useful for engineering applications. The modelling shows that climate warming will result in continuing wide-spread permafrost warming and degradation in Greenland, in agreement with present observations. We provide examples of application of the risk zone assessment approach for the two towns of Sisimiut and Ilulissat, both classified with high PTP.
Journal Article
Long-Term Safety of Roflumilast in Patients with Chronic Obstructive Pulmonary Disease, a Multinational Observational Database Cohort Study
2024
This study evaluated the long-term safety of roflumilast in patients with chronic obstructive pulmonary disease or chronic bronchitis using electronic healthcare databases from Germany, Norway, Sweden, and the United States (US).
The study population consisted of patients aged ≥40 years who had been exposed to roflumilast and a matched cohort unexposed to roflumilast. The matching was based on sex, age, calendar year of cohort entry date (2010-2011, 2012, or 2013), and a propensity score that included variables such as demographics, markers of chronic obstructive pulmonary disease (COPD) severity and morbidity, and comorbidities. In comparison to the unexposed matched cohort (never use), three exposure definitions were used for the exposed matched cohort: ever use, use status (current, recent, past use), and cumulative duration of use. The main outcome was 5-year all-cause mortality. Cox regression models were used to estimate crude and adjusted hazard ratios (HRs) and 95% confidence intervals (CI).
112,541 unexposed and 23,239 exposed patients across countries were included. Some variables remained unbalanced after matching, indicating higher COPD disease severity among the exposed patients. Adjusted HRs of 5-year all-cause mortality for \"ever use\" of roflumilast, compared to \"never use\", were 1.12 (95% CI, 1.08-1.17) in Germany, 1.00 (95% CI, 0.92-1.08) in Norway, 0.98 (95% CI, 0.92-1.04) in Sweden, and 1.16 (95% CI, 1.12-1.20) in the US. Compared to never users, there was a decrease in 5-year mortality risk observed among \"current users\" in Germany (HR: 0.93, 95% CI: 0.88-0.98), Norway (HR: 0.77, 95% CI: 0.67-0.87), and Sweden (HR: 0.80, 95% CI: 0.73-0.88).
There was no observed increase in 5-year mortality risk with the use of roflumilast in Sweden or Norway. A small increase in 5-year mortality risk was observed in Germany and the US in the ever versus never comparison, likely due to residual confounding by indication.
Journal Article
Test‐retest and time dependent variation and diagnostic values of vibratory sensation determined by biothesiometer and the Rydel‐Seiffer tuning fork
2021
Background and aims Polyneuropathy is a common neurological disorder with many potential causes. An essential part in screening, diagnosis, and follow‐up evaluation of polyneuropathy is testing of the sensory function including vibratory sensation. The graduated Rydel‐Seiffer tuning fork and the biothesiometer have been developed to quantify vibratory sensation through detection thresholds. The aim of this study is to compare the vibration detection thresholds determined by the two instruments regarding intraindividual temporal changes, interindividual variation in healthy subjects and comparison of the diagnostic value in patients with a clinical suspicion of polyneuropathy. Methods Ninety‐four healthy subjects, 98 patients with and 97 patients without a diagnosis of polyneuropathy were included. Quantitative sensory testing including biothesiometry, structured clinical examination, and nerve conduction studies were performed three times during 52 weeks in healthy subjects and once in patients. Results There were no significant changes over time for neither the Rydel‐Seiffer tuning fork nor the biothesiometer, and both had larger between‐subject variation than within‐subject variation. Relative intertrial variability was largest for the biothesiometer. Diagnostic value (sensitivity, specificity, positive predictive value, and negative predictive value) was moderate for both methods (Rydel‐Seiffer tuning fork: 58%, 74%, 70%, 64%; biothesiometer: 47%, 77%, 68%, 59%). Interpretation The Rydel‐Seiffer tuning fork and the biothesiometer have a low test‐retest and time dependent variation. They perform almost equally as diagnostic tools in patients with suspected polyneuropathy with a tendency toward better performance of the tuning fork. The graduated Rydel‐Seiffer tuning fork and the biothesiometer have been developed to quantify vibratory sensation through detection thresholds. We compared intra‐individual temporal changes, inter‐individual variation in healthy subjects and comparison of diagnostic value in patients with a clinical suspicion of polyneuropathy. They both have a low test‐retest and time dependent variation and perform almost equally as diagnostic tools in patients with suspected polyneuropathy with a tendency towards better performance of the tuning fork.
Journal Article
Mechanisms to control laser-plasma coupling in laser wakefield electron acceleration
by
Murphy, C. D.
,
Rajeev, P. P.
,
Lundh, O.
in
Adaptive control
,
Atom and Molecular Physics and Optics
,
Atom- och molekylfysik och optik (Här ingår: Kemisk fysik, kvantoptik)
2022
Experimental results, supported by precise modeling, demonstrate optimization of a plasma-based injector with intermediate laser pulse energy (<1J), corresponding to a normalized vector potentiala0=2.15, using ionization injection in a tailored plasma density profile. An increase in electron bunch quality and energy is achieved experimentally with the extension of the density downramp at the plasma exit. Optimization of the focal position of the laser pulse in the tailored plasma density profile is shown to efficiently reduce electron bunch angular deviation, leading to a better alignment of the electron bunch with the laser axis. Single peak electron spectra are produced in a previously unexplored regime by combining an early focal position and adaptive optic control of the laser wavefront by optimizing the symmetry of the prefocal laser energy distribution. Experimental results have been validated through particle-in-cell simulations using realistic laser energy, phase distribution, and temporal envelope, allowing for accurate predictions of difficult to model parameters, such as total charge and spatial properties of the electron bunches, opening the way for more accurate modeling for the design of plasma-based accelerators.
Journal Article