| 1. |
- Agrell, Erik, 1965, et al.
(författare)
-
Roadmap on optical communications
- 2024
-
Ingår i: Journal of Optics. - 2040-8978 .- 2040-8986. ; 26:9
-
Forskningsöversikt (refereegranskat)abstract
- The Covid-19 pandemic showed forcefully the fundamental importance broadband data communication and the internet has in our society. Optical communications forms the undisputable backbone of this critical infrastructure, and it is supported by an interdisciplinary research community striving to improve and develop it further. Since the first ‘Roadmap of optical communications’ was published in 2016, the field has seen significant progress in all areas, and time is ripe for an update of the research status. The optical communications area has become increasingly diverse, covering research in fundamental physics and materials science, high-speed electronics and photonics, signal processing and coding, and communication systems and networks. This roadmap describes state-of-the-art and future outlooks in the optical communications field. The article is divided into 20 sections on selected areas, each written by a leading expert in that area. The sections are thematically grouped into four parts with 4-6 sections each, covering, respectively, hardware, algorithms, networks and systems. Each section describes the current status, the future challenges, and development needed to meet said challenges in their area. As a whole, this roadmap provides a comprehensive and unprecedented overview of the contemporary optical communications research, and should be essential reading for researchers at any level active in this field.
|
|
| 2. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Optimization of Transmitter-Side Signal Rotations in the Presence of Laser Phase Noise
- 2020
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 38:15, s. 3850-3858
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of transmitter-side multidimensional signal rotations on the performance of multichannel optical transmission are studied in the presence of laser phase noise. In particular, the laser phase noise is assumed to be uncorrelated between channels. To carry out this study, a simple multichannel laser-phase-noise model that has been experimentally validated for weakly-coupled multicore-fiber transmission is considered. As the considered rotation scheme is intended to work in conjunction with receiver-side carrier phase estimation (CPE), the model is modified to further assume that imperfect CPE has taken place, leaving residual phase noise in the processed signal. Based on this model, two receiver structures are derived and used to numerically optimize transmitter-side signal rotations through Monte Carlo simulations. For reasonable amounts of residual phase noise, rotations based on Hadamard matrices are found to be near-optimal for transmission of four-dimensional signals. Furthermore, Hadamard rotations can be performed for any dimension that is a power of two. By exploiting this property, an increase of up to 0.25 bit per complex symbol in an achievable information rate is observed for transmission of higher-order constellations.
|
|
| 3. |
- Alfredsson, Arni, 1989, et al.
(författare)
-
Pilot Distributions for Joint-Channel Carrier-Phase Estimation in Multichannel Optical Communications
- 2020
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 38:17, s. 4656-4663
-
Tidskriftsartikel (refereegranskat)abstract
- Joint-channel carrier-phase estimation can improve the performance of multichannel optical communication systems. In the case of pilot-aided estimation, the pilots are distributed over a two-dimensional channel-time symbol block that is transmitted through multiple channels. However, suboptimal pilot distributions reduce the effectiveness of the carrier-phase estimation and thus result in unnecessary pilot overhead, which reduces the overall information rate of the system. It is shown that placing pilots identically in all channels is suboptimal in general. By instead optimizing the pilot distribution, the mean squared error of the phase-noise estimates can be decreased by over 90% in some cases. Moreover, it is shown that the achievable information rate can be increased by up to 0.05, 0.16, and 0.41 bits per complex symbol for dual-polarization 20 GBd transmission of 64-ary, 256-ary, and 1024-ary quadrature amplitude modulation over 20 four-dimensional channels, respectively, assuming a total laser linewidth of 200 kHz.
|
|
| 4. |
- Amkreutz, J. A. M. P., et al.
(författare)
-
Association Between Bone Mineral Density and Autoantibodies in Patients With Rheumatoid Arthritis
- 2021
-
Ingår i: Arthritis and Rheumatology. - : Wiley. - 2326-5191 .- 2326-5205. ; 73:6, s. 921-930
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Autoantibodies, such as anti–citrullinated protein antibodies (ACPAs), have been described as inducing bone loss in rheumatoid arthritis (RA), which can also be reflected by bone mineral density (BMD). We therefore examined the association between osteoporosis and autoantibodies in two independent RA cohorts. Methods: Dual x-ray absorptiometry (DXA) of the lumbar spine and left hip was performed in 408 Dutch patients with early RA during 5 years of follow-up and in 198 Swedish patients with early RA during 10 years of follow-up. The longitudinal effect of ACPAs and other autoantibodies on several BMD measures was assessed using generalized estimating equations. Results: In the Dutch cohort, significantly lower BMD at baseline was observed in ACPA-positive patients compared to ACPA-negative patients, with an estimated marginal mean BMD in the left hip of 0.92 g/cm2 (95% confidence interval [95% CI] 0.91–0.93) versus 0.95 g/cm2 (95% CI 0.93–0.97) (P = 0.01). In line with this, significantly lower Z scores at baseline were noted in the ACPA-positive group compared to the ACPA-negative group (estimated marginal mean Z score in the left hip of 0.18 [95% CI 0.08–0.29] versus 0.48 [95% CI 0.33–0.63]) (P < 0.01). However, despite clear differences at baseline, ACPA positivity was not associated with greater decrease in absolute BMD or Z scores over time. Furthermore, there was no association between BMD and higher levels of ACPAs or other autoantibodies (rheumatoid factor and anti–carbamylated protein antibodies). In the Swedish cohort, ACPA-positive patients tended to have a higher prevalence of osteopenia at baseline (P = 0.04), but again, ACPA positivity was not associated with an increased prevalence of osteopenia or osteoporosis over time. Conclusion: The presence of ACPAs is associated with significantly lower BMD at baseline, but not with greater BMD loss over time in treated RA patients. These results suggest that ACPAs alone do not appear to contribute to bone loss after disease onset when disease activity is well-managed. © 2020 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.
|
|
| 5. |
- Andersson, Elias, 1989-
(författare)
-
Enabling industrial energy benchmarking : Process-level energy end-use, key performance indicators, and efficiency potential
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the greatest challenges of our time is global climate change. A key strategy for mitigating the emission of greenhouse gases is the improvement of energy efficiency. Manufacturing industry stands for a large share of global energy end-use but has yet to achieve its full energy efficiency potential. A barrier to untapping this potential is the lack of detailed data on industrial energy end-use at the process level, preventing the development of sound, bottom-up energy key performance indicators (KPIs). This hampers the ability to create a profound strategy for improving industrial energy efficiency because it is not known in which end-use processes the largest energy efficiency potential is to be found. Increasing knowledge about energy end-use at the process level also increases the possibility for energy comparisons, i.e. benchmarking, at the process level.This thesis aimed to investigate how to further enable industrial energy benchmarking at the process level, primarily for the pulp and paper and wood industries. Relevant benchmarking requires that data on energy end-use is collected using a common, harmonized categorization of processes and that joint energy KPIs are applied. Therefore, suggestions for standardized categorizations of end-use processes were investigated for the studied industries.Based on the calculations, and under the assumptions made in this thesis for estimating the energy efficiency potential of end-use processes, diversity was found between industries around which type of processes have the largest efficiency potential. It also emerged that, due to the lack of detailed data about energy end-use and lack of information about energy efficiency measures, processes accounting for a significant share of the energy efficiency potential in the wood industry risk being overlooked. It is not certain that current energy policies are sufficient to reach the full potential identified. The lack of information about energy end-use and energy efficiency measures implies that neither industrial actors nor policy-makers are able to develop thorough energy strategies or roadmaps for improved energy efficiency.While the outcomes of this thesis show that a large share of Swedish pulp and paper mills carry out energy benchmarking to some degree, energy managers emphasized that benchmarking in this particular industry is difficult because it requires a deep understanding of the industry’s heterogenous and integrated processes. This thesis proposes a widened perspective on energy benchmarking and its role in industrial energy management; namely, also considering the process of how energy KPIs are implemented within in-house energy management. A process that enhances energy management includes the continuous monitoring, visualization, and revision of KPIs. In this thesis, a method is developed that encourages the bottom-up implementation of energy KPIs in the pulp and paper industry, which further enables industrial energy benchmarking.
|
|
| 6. |
- Andrekson, Peter, 1960, et al.
(författare)
-
Fiber-based phase-sensitive optical amplifiers and their applications
- 2020
-
Ingår i: Advances in Optics and Photonics. - 1943-8206. ; 12:2, s. 367-428
-
Tidskriftsartikel (refereegranskat)abstract
- Optical parametric amplifiers rely on second-order susceptibility (three-wave mixing) or third-order susceptibility (four-wave mixing) in a nonlinear process where the energy of incoming photons is not changed (elastic scattering). In the latter case, two pump photons are converted to a signal and to an idler photon. Under certain conditions, related to the phase evolution of the waves involved, this conversion can be very effi-cient, resulting in large amplification of an input signal. As the nonlinear process can be very fast, all-optical applications aside from pure amplification are also possible. If the amplifier is implemented in an optical input-phase-sensitive manner, it is possible to amplify a signal wave without excess noise, i.e., with a noise figure of 0 dB. In this paper, we will provide the fundamental concepts and theory of such amplifiers, with a focus on their implementation in highly nonlinear optical fibers relying on four-wave mixing. We will discuss the distinctions between phase-insensitive and phase-sensitive operation and include several experimental results to illustrate their capability. Different applications of parametric amplifiers are also discussed, including their use in optical communication links.
|
|
| 7. |
- Bergman, Erika, et al.
(författare)
-
Time trends in pediatric fractures in a Swedish city from 1950 to 2016
- 2020
-
Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 91:5, s. 598-604
-
Tidskriftsartikel (refereegranskat)abstract
- Background and purpose — As previous studies indicate time trends in pediatric fracture incidence, we followed the incidence in a Swedish city between 1950 and 2016. Patients and methods — Malmö city, Sweden had 322,574 inhabitants in 2015. We used diagnosis registry, charts, and radiographs of the only city hospital to classify fractures in individuals < 16 years in 2014–2016, and compared these with data from 1950–2006. We used joinpoint regression to analyze time trends and present results as mean annual percentage changes (APC). Differences between periods are described as incident rate ratios (IRR). To describe uncertainty, 95% confidence intervals (CI) are used. Results — During 2014–2016 the pediatric fracture incidence was 1,786 per 105 person-years (boys 2,135 and girls 1,423). From 1950 onwards age-adjusted fracture incidence increased until 1979 in both boys (APC +1.5%, CI 1.2–1.8) and girls (APC +1.6%, CI 0.8–2.5). The incidence remained stable from 1979 to 2016 (APC in boys 0.0%, CI –0.3 to 0.3 and in girls –0.2%, CI –1.1 to 0.7). Age-adjusted incidence 2014–2016 was higher than 2005–2006 in girls (IRR 1.1, CI 1.03–1.3), but not in boys (IRR 1.0, CI 0.9–1.1). Interpretation — Fracture incidence was in girls higher in 2014–2016 than in 2005–2006. However, only with more than 2 measuring points are meaningful trend analyses possible. When we analyzed the period 1950–2016 with 17 measuring points and joinpoint regression, we found that fracture incidence increased in both sexes until 1979 but has thereafter been stable.
|
|
| 8. |
- Bergman, Erika, et al.
(författare)
-
Time trends in pediatric hand fracture incidence in Malmö, Sweden, 1950–2016
- 2021
-
Ingår i: Journal of Orthopaedic Surgery and Research. - : Springer Science and Business Media LLC. - 1749-799X. ; 16:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The hand is the second most fractured region in children. It is therefore important to update fracture epidemiology to be able to identify time trends for adequate health care planning. This study reports pediatric hand fracture incidence 2014–2016 and, using published data, also long-term time trends in 1950–2016. Patients and methods: The Swedish city of Malmö, with 328,494 inhabitants in 2016, has only one hospital. We used the hospital radiological archive, medical charts, and diagnosis registry to identify hand fractures in city residents < 16 years in 2014–2016. These data were compared to those from three published studies that evaluated periods in 1950–2006. Differences between two periods were calculated as both unadjusted and age- and sex-adjusted incident rate ratios (IRR) with 95% confidence intervals (95% CI). We used joinpoint regression to estimate time trends during the entire period and present annual percent changes (APC) with 95% CI. Results: In 2014–2016 phalangeal fractures accounted for 71% of all hand fractures, metacarpal fractures for 24%, and carpal fractures for 5%. We identified 615 hand fractures (419 in boys and 196 in girls) during 181,617 person-years in 2014–2016, resulting in an unadjusted pediatric hand fracture incidence of 339/100,000 person-years (boys 452/100,000 person-years and girls 220/100,000 person-years). The age-adjusted incidence 2014–2016 was similar to 2005–2006, the most recently evaluated period (IRR in boys 0.9; 95% CI 0.8 to 1.01, and in girls 1.0; 95% CI 0.8 to 1.2). Looking at the entire period 1950–2016, we found that age-adjusted incidence increased in 1950–1979, in boys by APC + 3.8%; 95% CI 3.0 to 4.5 and in girls by + 3.9%; 95% CI 2.8 to 5.0, but decreased in 1979–2016, in boys by − 0.7%; 95% CI − 1.4 to − 0.003, and girls by − 1.3%; 95% CI − 2.4 to − 0.1. Conclusions: Phalangeal fractures accounted for about three quarters of all hand fractures. The age-adjusted hand fracture incidence increased in both sexes in 1950–1979 and decreased in 1979–2016. Level of evidence: III
|
|
| 9. |
- Bokrantz, Tove, et al.
(författare)
-
The association between peripheral arterial disease and risk for hip fractures in elderly men is not explained by low hip bone mineral density. Results from the MrOS Sweden study
- 2022
-
Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 33, s. 2607-2617
-
Tidskriftsartikel (refereegranskat)abstract
- In this prospective study in Swedish elderly men, PAD based on an ABI < 0.9 was associated with an increased risk of hip fracture, independent of age and hip BMD. However, after further adjustments for comorbidity, medications, physical function, and socioeconomic factors, the association diminished and was no longer statistically significant. Introduction To examine if peripheral arterial disease (PAD) is associated with an increased risk for hip fracture in men independent of hip BMD. Methods Ankle-brachial index (ABI) was assessed in the Swedish MrOS (Osteoporotic Fractures in Men) study, a prospective observational study including 3014 men aged 69-81 years at baseline. PAD was defined as ABI < 0.90. Incident fractures were assessed in computerized X-ray archives. The risk for hip fractures was calculated using Cox proportional hazard models. At baseline, BMD was assessed using DXA (Lunar Prodigy and Hologic QDR 4500) and functional measurements and blood samples were collected. Standardized questionnaires were used to collect information about medical history, falls, and medication. Results During 10 years of follow-up, 186 men had an incident hip fracture. The hazard ratio (HR) for hip fracture in men with PAD was 1.70 (95% CI 1.14-2.54), adjusted for age and study site. Additional adjustment for total hip BMD marginally affected this association (HR 1.64; 95% CI 1.10-2.45). In a final multivariate model, the HR attenuated to a non-significant HR 1.38 (95% CI 0.91-2.11) adjusted for age, site, hip BMD, BMI, falls, smoking, eGFR, handgrip strength, walking speed, former hip fracture, antihypertensive treatment, diabetes, education, and history of cardiovascular disease. Conclusion This study suggests that PAD is associated with an increased risk for hip fracture independently of hip BMD in elderly Swedish men. However, the high frequency of comorbidity and lower physical performance among men with PAD might partly explain this association.
|
|
| 10. |
- Brajato, Giovanni, et al.
(författare)
-
Bayesian filtering framework for noise characterization of frequency combs
- 2020
-
Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 28:9, s. 13949-13964
-
Tidskriftsartikel (refereegranskat)abstract
- Amplitude and phase noise correlation matrices are of fundamental importance for studying noise properties of frequency combs. They include information about the origin of noise sources as well as the scaling and correlation of the noise across the comb lines. These matrices provide an insight that is essential for obtaining low-noise performance which is important for, e.g., applications in optical communication, low–noise microwave signal generation, and distance measurements. Estimation of amplitude and phase noise correlation matrices requires highly–accurate measurement technique which can distinguishes between noise sources coming from the frequency comb and the measurement system itself. Bayesian filtering provides a theoretically optimum approach for filtering of measurement noise and thereby, the most accurate measurement of phase and amplitude noise. In this paper, a novel Bayesian filtering based framework for joint estimation of amplitude and phase noise of multiple frequency comb lines is proposed, and demonstrated for phase noise characterization. Compared to the conventional approaches, that do not employ any measurement noise filtering, the proposed approach provides significantly more accurate measurements of correlation matrices, operates over a wide range of signal–to–noise–ratios and gives an insight into comb’s dynamics at short scales (<10−8 s). © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
|
|
