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1.	He, Zonglong, 1994, et al. (författare) Experimental Demonstration of Learned Pulse Shaping Filter for Superchannels 2022 Ingår i: 2022 Optical Fiber Communications Conference and Exhibition, OFC 2022 - Proceedings. Konferensbidrag (refereegranskat)abstract We demonstrate a pulse shaping filter enabled by machine learning for spectral superchannels. In contrast to a 1% roll-off root-raised cosine filter, our learned filter reduces the adaptive equalizer length by 47% for the same spectral efficiency.
2.	He, Zonglong, 1994, et al. (författare) Periodicity-Enabled Size Reduction of Symbol Based Predistortion for High-Order QAM 2022 Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 40:18, s. 6168-6178 Tidskriftsartikel (refereegranskat)abstract We experimentally demonstrate a novel size reduction approach for symbol-based look-up table (LUT) digital predistortion (DPD) of the transmitter impairments taking advantage of the periodicity in the pattern-dependent distortions. Compared to other reduced-size LUT schemes, the proposed method can significantly lessen the storage memory requirements with negligible performance penalty for high-order modulation formats. To further alleviate the storage memory restriction, a twice reduced-size LUT scheme is proposed to provide further size reduction. Importantly, given a targeted memory length, we verify the importance of averaging over sufficient occurrences of the patterns to obtain a well-performing LUT. Moreover, it is necessary to evaluate the performance of LUT-based DPD using random data. Finally, we demonstrate a neural network (NN) based nonlinear predistortion technique, which achieves nearly identical performance to the full-size LUT for all employed constellations and is robust against a change of modulation format. The proposed techniques are verified in a back-to-back transmission experiment of 20 Gbaud 64-QAM, 256-QAM, and 1024-QAM signals considering 3 and 5 symbol memory. The performance of the LUT-based DPD is further validated in a noise loading experiment.
3.	He, Zonglong, 1994, et al. (författare) Symbol-Based Supervised Learning Predistortion for Compensating Transmitter Nonlinearity 2021 Ingår i: 2021 European Conference on Optical Communication, ECOC 2021. - 9781665438681 Konferensbidrag (refereegranskat)abstract We experimentally demonstrate a symbol-based nonlinear digital predistortion (DPD) technique utilizing supervised learning, which is robust against a change of modulation format. Back-to-back transmission of 30 Gbaud 32, 64 and 256QAM confirms that our scheme significantly outperforms the baseline of arcsine-based predistortion.
4.	de Peppo, Giuseppe Maria, 1981, et al. (författare) Osteogenic response of human mesenchymal stem cells to well-defined nanoscale topography in vitro 2014 Ingår i: International journal of nanomedicine. - : Informa UK Limited. - 1176-9114 .- 1178-2013. ; 9:1, s. 2499-2515 Tidskriftsartikel (refereegranskat)abstract Background: Patterning medical devices at the nanoscale level enables the manipulation of cell behavior and tissue regeneration, with topographic features recognized as playing a significant role in the osseointegration of implantable devices. Methods: In this study, we assessed the ability of titanium-coated hemisphere-like topographic nanostructures of different sizes (approximately 50, 100, and 200 nm) to influence the morphology, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs). Results: We found that the proliferation and osteogenic differentiation of hMSCs was influenced by the size of the underlying structures, suggesting that size variations in topographic features at the nanoscale level, independently of chemistry, can be exploited to control hMSC behavior in a size-dependent fashion. Conclusion: Our studies demonstrate that colloidal lithography, in combination with coating technologies, can be exploited to investigate the cell response to well defined nanoscale topography and to develop next-generation surfaces that guide tissue regeneration and promote implant integration.
5.	Jiang, Nan, et al. (författare) Stochastic Backpropagation for Coherent Optical Communications 2011 Ingår i: European Conference and Exposition on Optical Communications, ECOC. - Washington, D.C. : OSA. - 2162-2701. - 9781557529312 - 9781557529312 Konferensbidrag (refereegranskat)abstract We present stochastic backpropagation, a novel maximum a posteriori detection method for coherent optical communication. The proposed detector is shown to outperform conventional backpropagation in a scenario where nonlinear phase noise is the dominant impairment.
6.	Johannisson, Pontus, 1976, et al. (författare) Convergence Comparison of CMA and ICA for Blind Polarization Demultiplexing of QPSK and 16-QAM Signals 2010 Ingår i: Proceedings of European Conference on Optical Communication, ECOC 2010, Turin, Italy, September 19-23, 2010. - 9781424485352 ; 1-2 Konferensbidrag (refereegranskat)abstract Two algorithms for blind polarization demultiplexing, based on the constant modulus criterion and independent component analysis, are compared. It is found that the latter converges significantly faster to within a given SNR penalty tolerance.
7.	Johannisson, Pontus, 1976, et al. (författare) Convergence Comparison of the CMA and ICA for Blind Polarization Demultiplexing 2011 Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 3:6, s. 493-501 Tidskriftsartikel (refereegranskat)abstract An algorithm based on independent component analysis for blind polarization demultiplexing in a coherent transmission system is presented. A comparison with the constant modulus algorithm in terms of the convergence properties is performed, and it is found that the suggested algorithm has a significantly faster convergence rate and does not have any singularity problems. We also demonstrate that the algorithm convergence is strongly dependent on the choice of starting condition and show how this can be exploited to increase the convergence rate.
8.	Johannisson, Pontus, 1976, et al. (författare) Modified constant modulus algorithm for polarization-switched QPSK 2011 Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:8, s. 7734-7741 Tidskriftsartikel (refereegranskat)abstract A modified constant modulus algorithm (CMA) is presentedthat allows polarization demultiplexing and equalization of polarizationswitchedQPSK. An implementation is suggested that allows easy switchingbetween the traditional and the modified CMA. Using numerical simulations,the suggested algorithm is shown to have similar performance asCMA has for polarization-multiplexed QPSK.
9.	Karlsson, Magnus, 1967, et al. (författare) The fiber optic parametric amplifier and its applications for high-capacity communication and all-optical sampling 2003 Ingår i: DOPS-NYT. ; 18:4, s. 16-19 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The fiber optic parametric amplifier (FOPA) has a wide range of application in high-capacity fiber communications. We review some recent results such as the FOPA used for pulse generation, WDM amplification and all-optical sampling.
10.	Karout, Johnny, 1985, et al. (författare) CMA Misconvergence in Coherent Optical Communication for Signals Generated from a Single PRBS 2011 Ingår i: Wireless & optical communications conference, New Jersey, 15-16 April 2011. - 9781457704543 Konferensbidrag (refereegranskat)abstract In the experimental study of modulators for coherent optical communications, it is common to generate multilevel signals using a single pseudo-random binary sequence. This simple experimental realization leads to symbol correlation. When modulators are studied in combination with adaptive receiver algorithms that rely on independent data, misconvergence may result. In this contribution, we investigate the impact of such correlation on a standard blind equalization method and provide guidelines to avoid misconvergence. Our results indicate that care needs to be taken when using a single PRBS sequence and that decorrelation delays must be chosen appropriately. We present simulation and theoretical results for 16-QAM, and show how our results can be applied to other multi-level constellations.
11.	Kylemark, Per, 1976, et al. (författare) Noise statistics of fiber optical parametric amplifiers 2006 Ingår i: OFC/NFOEC 2006. 2006 Optical Fiber Communication Conference and National Fiber Optic Engineers Conference. ; , s. OWT5- Konferensbidrag (refereegranskat)abstract We show both theoretically and experimentally that the probability density function of a signal amplified by parametric amplifiers with pump excess noise is non-Gaussian and asymmetric. This impacts the relationship between the noise figure and the bit-error rate
12.	Lu, Guo-Wei, 1976, et al. (författare) Format Conversion From 120-Gb/s RZ-D8PSK to 80-Gb/s RZ-DQPSK Through FWM-Based Optical Phase Erasure 2010 Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 22:24, s. 1817-1819 Tidskriftsartikel (refereegranskat)abstract An optical format conversion scheme from 120-Gb/s return-to-zero differential 8-ary phase-shift keying (RZ-D8PSK) to 80-Gb/s RZ differential quadrature phase-shift keying (RZ-DQPSK) is demonstrated by optically removing one tributary through optical phase erasure. It is achieved through four-wave mixing in a highly nonlinear fiber. An 8-dB sensitivity improvement is obtained for the converted DQPSK signal relative to that of the input D8PSK signal. This is potentially useful to enable the interconnection among neighboring networks where different formats are deployed.
13.	Lu, Guo-Wei, 1976, et al. (författare) Format Conversion of Optical Multilevel Signals Using FWM-Based Optical Phase Erasure 2011 Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:16, s. 2460-2466 Tidskriftsartikel (refereegranskat)abstract An optical format conversion scheme of multilevel phase-shift keying (M-ary PSK) signals using the four-wave mixing based optical phase erasure is discussed in this paper. The conversion from differential quadrature phase-shift keying (DQPSK) to differential phase shift keying at 10 and 160 Gbaud, and the conversion from differential eight-ary phase-shift keying to DQPSK at 40 Gbaud have been experimentally demonstrated. The proposed scheme could be used as a phase erasure, in which a redundant tributary of the M-ary PSK signal is removed, or as an "updater" where the unwanted phase pattern is replaced with the new pattern.
14.	Peng, Fangrong, 1986, et al. (författare) Operational Regime of Symbol-by-Symbol Phase Noise Estimation for POLMUX 16-QAM 2010 Ingår i: Proceedings of European Conference on Optical Communication, ECOC, Turin, Italy, September 19-23, 2010. - 9781424485352 ; 1-2 Konferensbidrag (refereegranskat)abstract A symbol-by-symbol phase noise estimation algorithm for polarization-multiplexed 16-QAM is evaluated. We found that it can cope with laser linewidths of up to 2.2 MHz in high SNR regimes, at 112 Gbit/s.
15.	Sen, Debarati, 1975, et al. (författare) MCRB for Timing and Phase Offset for Low-Rate Optical Communication with Self-Phase Modulation 2013 Ingår i: IEEE Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2558 .- 1089-7798. ; 17:5, s. 1004-1007 Tidskriftsartikel (refereegranskat)abstract We derive the modified Cramer-Rao bound (MCRB) for symbol timing and phase offset estimation in the presence of nonlinear self-phase modulation (SPM) in a dispersion compensated long-haul optical fiber link with coherent detection at data rates below 10 Gigabaud. In the presence of a low-pass filter at the receiver front-end, we find that SPM degrades the MCRB. Moreover, depending on the pulse shape, SPM induces underdamped oscillation on the bounds.
16.	Sjödin, Martin E, 1983, et al. (författare) Comparison of polarization-switched QPSK and polarization-multiplexed QPSK at 30 Gbit/s 2011 Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:8, s. 7839-7846 Tidskriftsartikel (refereegranskat)abstract We present the first experimental results for polarization-switched QPSK (PS-QPSK) and make a comparison with polarization-multiplexed QPSK. Our measurements confirm the predicted sensitivity advantage of PS-QPSK. We have also studied the single channel performance after transmission over 300 km and support the results with numerical simulations. It is shown that the two modulation formats have similar nonlinear tolerance and that optical dispersion compensation outperforms compensation with digital signal processing in the single channel case. Finally, we propose a novel transmitter for PS-QPSK based on an IQ modulator and two amplitude modulators driven in a push-pull configuration.
17.	Sjödin, Martin E, 1983, et al. (författare) Filter Optimization for Self-Homodyne Coherent WDM Systems using Interleaved Polarization Division Multiplexing 2011 Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:9, s. 1219 - 1226 Tidskriftsartikel (refereegranskat)abstract We examine the impact of filtering on self-homodynecoherent WDM systems using the interleaved polarization division multiplexing scheme. To investigate the performance limit and to provide more insight into previously obtained experimental results we perform numerical simulations in which different filter shapes and filter bandwidths are used. It is shown that with proper prefiltering of the data and filtering of the pilot tone in the receiver, performance can approach that of an intradyne system, which would make it possible to implement coherent systems with high spectral efficiency without any digitalsignal processing in the receiver.
18.	Sjödin, Martin E, 1983, et al. (författare) Interleaved Polarization Division Multiplexing in Self-Homodyne Coherent WDM Systems 2010 Ingår i: Proceedings of European Conference on Optical Communication, ECOC 2010, Turin, Italy, September 19-23, 2010. - 9781424485352 ; 1-2 Konferensbidrag (refereegranskat)abstract We demonstrate increased spectral efficiency for self-homodyne coherent WDM systems by using a novel interleaved polarization division multiplexing scheme.
19.	Sjödin, Martin E, 1983, et al. (författare) Measurement of the Phase Noise Tracking Capability of a Digital Coherent Receiver 2011 Ingår i: European Conference and Exposition on Optical Communications, ECOC 2011; Geneva; Switzerland; 18 September 2011 through 22 September 2011. - 2162-2701. - 9781557529312 Konferensbidrag (refereegranskat)abstract We present a method to evaluate the phase noise tracking performance of a digital coherent receiver. Measurements of the phase error variance of QPSK at different symbol rates are presented for two different algorithms.
20.	Tan, Ahmet Serdar, 1982, et al. (författare) An ML-based Detector for Optical Communication in the Presence of Nonlinear Phase Noise 2011 Ingår i: IEEE International Conference on Communications. - : IEEE. - 1550-3607. - 9781612842332 ; , s. Art. no. 5962741- Konferensbidrag (refereegranskat)abstract We present a closed-form maximum likelihood-based data detection algorithm for long-haul optical channels with dominant nonlinear phase noise induced by self-phase modulation. The closed-form detector is evaluated in terms of symbol error rate as a function of input power, and compared with other sub-optimal detectors as well as a non-parametric detector. We show that the performance of the detector deteriorates for high input power levels, resulting in an optimal operation region. We also provide insights into the behavior of the detector in the highly nonlinear regime.
21.	Tan, Ahmet Serdar, 1982, et al. (författare) Modified Cramer-Rao Bound for Clock Recovery in the Presence of Self-Phase Modulation 2012 Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 30:16, s. 2556-2562 Tidskriftsartikel (refereegranskat)abstract We investigate the effect of nonlinear self-phase modulation (SPM) on clock recovery in long-haul coherent optical communication systems with low to moderate baud rates. We consider dual-polarization, multilevel quadrature amplitude modulation, and evaluate conventional timing estimators as well as a modified Cramer-Rao bound. As the latter is hard to compute in the presence of nonlinear channel impairments, we derive an approximate closed-form expression. Contrary to linear channel impairments, the nonlinear impairments can degrade the performance for higher input powers. In addition, the bounds exhibit oscillatory behavior due to the oscillations in the signal spectrum in the presence of SPM.
22.	Tan, Ahmet Serdar, 1982, et al. (författare) The Impact of Self-Phase Modulation on Digital Clock Recovery in Coherent Optical Communication 2010 Ingår i: Proceedings of European Conference on Optical Communication, ECOC 2010, Turin, Italy, September 19-23, 2010. - 9781424485352 ; 1-2 Konferensbidrag (refereegranskat)abstract The impact of self-phase modulation on the estimation error variance of digital clock recovery schemes for coherent 16-QAM dual-polarization systems is investigated. The error variance increases severely compared to the linear case and the theoretical bounds.
23.	Abdellah, Tebani, et al. (författare) Integration of molecular profiles in a longitudinal wellness profiling cohort. 2020 Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1 Tidskriftsartikel (refereegranskat)abstract An important aspect of precision medicine is to probe the stability in molecular profiles among healthy individuals over time. Here, we sample a longitudinal wellness cohort with 100 healthy individuals and analyze blood molecular profiles including proteomics, transcriptomics, lipidomics, metabolomics, autoantibodies andimmune cell profiling, complementedwith gut microbiota composition and routine clinical chemistry. Overall, our results show high variation between individuals across different molecular readouts, while the intra-individual baseline variation is low. The analyses show that each individual has a unique and stable plasma protein profile throughout the study period and that many individuals also show distinct profiles with regards to the other omics datasets, with strong underlying connections between the blood proteome and the clinical chemistry parameters. In conclusion, the results support an individual-based definition of health and show that comprehensive omics profiling in a longitudinal manner is a path forward for precision medicine.
24.	Bäcklund, Katarina, 1982-, et al. (författare) Showcasing the First Steps Towards a Digital Twin for Campus Environments 2022 Ingår i: 2022 BuildSim Nordic. - : EDP Sciences. Konferensbidrag (refereegranskat)abstract This paper presents a path towards the implementation of a Digital Twin for campus environments. The main purpose of the Digital Twin is to accomplish an advanced analytical tool, which supports building owners, building operators and building users to reach an improved performance of the building. Digital Twins is new to the building and the real estate industry, hence research within this field is scarce. This paper contributes to the research by providing a methodology to implement a Digital Twin of an existing building stock of campus areas in Sweden. The main results obtained so far are presented. They indicate that the potential of a Digital Twin expands beyond the aspects of a navigational digital 3D model, including a state-of-the-art app that is developed from the Digital Twin platform.
25.	Chen, Zexin, et al. (författare) Transmitter optimization for PS-QAM signal in high spectral efficiency metro-transmission 2023 Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 41, s. 1-10 Tidskriftsartikel (refereegranskat)abstract Probabilistic constellation shaping (PCS) brings unprecedented flexibility to future optical networks. However, PCS combined with higher-order modulation formats and higher symbol rates puts more demands on the transmitter. For metro-transmission with high spectral efficiency (SE), transmitter impairments are responsible for a major portion of the system constraints. To address this issue, in this work we study the impact of transmitter impairments on probabilistically shaped quadrature amplitude modulation (PS-QAM) signals. First, we investigate the impact of transmitter impairments and radio frequency (RF) amplifier noise on the optimum shaping factor and the modulation depth within a fiber link. Then, we explore how generalized mutual information (GMI) and the shaping factor are affected by the noise from the transmitter. Next, we first jointly optimize the arcsine swing and the clipping ratio, in order to mitigate the transmitter impairments for the PS-QAM signal, when the modulation depth, the noise from the transmitter, the noise from the fiber optical channel, and the shaping factor are fixed. Then, we verify its validity for various configurations of transmission system. The optimized parameters primarily depend on the noise from the transmitter and turn out to be insensitive to the noise from the fiber optical link and the shaping factor. Finally, we experimentally verify the optimization strategy with PS-256QAM in back-to-back (B2B) transmission.
26.	Deriushkina, Ekaterina, 1992, et al. (författare) Characterisation of a Coupled-Core Fiber Using Dual-Comb Swept-Wavelength Interferometry 2021 Ingår i: 2021 European Conference on Optical Communication, ECOC 2021. Konferensbidrag (refereegranskat)abstract We present a measurement of the transfer matrix of a coupled three-core fiber using a novel combination of swept-wavelength interferometry and dual-comb spectroscopy capable of measuring 1 THz bandwidth with a frequency resolution of 50 kHz with only a 25 GHz laser sweep.
27.	Deriushkina, Ekaterina, 1992, et al. (författare) Dual-Comb Swept-Wavelength Interferometry : Theory and Experiment 2022 Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 0733-8724 .- 1558-2213. ; 40:19, s. 6508-6516 Tidskriftsartikel (refereegranskat)abstract Much efforts have been put to elaborate and improve different high precision measurement schemes for characterization of advanced photonic devices and optical fibers with increasing bandwidth requirements. In light of this, swept-wavelength interferometry and dual-comb spectroscopy have been extensively applied in characterization procedures. In this paper we present in detail an experimental scheme that combines these two techniques and overcomes their limitations by using a tunable laser source in order to sweep over the frequency comb spacing and capture all intermediate frequencies. We demonstrate full-field broadband measurements over 1.25 THz comb bandwidth with increased frequency resolution, which can be performed in only 5 ms sweep. We also show that the nonlinearity of the laser sweep can be removed without an auxiliary interferometer in the setup.
28.	Edin, Carl, et al. (författare) Ectopic fat is associated with cardiac remodeling - A comprehensive assessment of regional fat depots in type 2 diabetes using multi-parametric MRI. 2022 Ingår i: Frontiers in Cardiovascular Medicine. - : Frontiers Media SA. - 2297-055X. ; 9 Tidskriftsartikel (refereegranskat)abstract Background: Different regional depots of fat have distinct metabolic properties and may relate differently to adverse cardiac remodeling. We sought to quantify regional depots of body fat and to investigate their relationship to cardiac structure and function in Type 2 Diabetes (T2D) and controls.Methods: From the SCAPIS cohort in Linköping, Sweden, we recruited 92 subjects (35% female, mean age 59.5 ± 4.6 years): 46 with T2D and 46 matched controls. In addition to the core SCAPIS data collection, participants underwent a comprehensive magnetic resonance imaging examination at 1.5 T for assessment of left ventricular (LV) structure and function (end-diastolic volume, mass, concentricity, ejection fraction), as well as regional body composition (liver proton density fat fraction, visceral adipose tissue, abdominal subcutaneous adipose tissue, thigh muscle fat infiltration, fat tissue-free thigh muscle volume and epicardial adipose tissue).Results: Compared to the control group, the T2D group had increased: visceral adipose tissue volume index (P < 0.001), liver fat percentage (P < 0.001), thigh muscle fat infiltration percentage (P = 0.02), LV concentricity (P < 0.001) and LV E/e'-ratio (P < 0.001). In a multiple linear regression analysis, a negative association between liver fat percentage and LV mass (St Beta -0.23, P < 0.05) as well as LV end-diastolic volume (St Beta -0.27, P < 0.05) was found. Epicardial adipose tissue volume and abdominal subcutaneous adipose tissue volume index were the only parameters of fat associated with LV diastolic dysfunction (E/e'-ratio) (St Beta 0.24, P < 0.05; St Beta 0.34, P < 0.01, respectively). In a multivariate logistic regression analysis, only visceral adipose tissue volume index was significantly associated with T2D, with an odds ratio for T2D of 3.01 (95% CI 1.28-7.05, P < 0.05) per L/m2 increase in visceral adipose tissue volume.Conclusions: Ectopic fat is predominantly associated with cardiac remodeling, independently of type 2 diabetes. Intriguingly, liver fat appears to be related to LV structure independently of VAT, while epicardial fat is linked to impaired LV diastolic function. Visceral fat is associated with T2D independently of liver fat and abdominal subcutaneous adipose tissue.
29.	Edin, Carl, et al. (författare) Liver fibrosis is associated with left ventricular remodeling : insight into the liver-heart axis 2024 Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. Tidskriftsartikel (refereegranskat)abstract Objective: In non-alcoholic fatty liver disease (NAFLD), liver fibrosis is the strongest predictor of adverse outcomes. We sought to investigate the relationship between liver fibrosis and cardiac remodeling in participants from the general population using magnetic resonance imaging (MRI), as well as explore potential mechanistic pathways by analyzing circulating cardiovascular biomarkers.Methods: In this cross-sectional study, we prospectively included participants with type 2 diabetes and individually matched controls from the SCAPIS (Swedish CArdioPulmonary bioImage Study) cohort in Linköping, Sweden. Between November 2017 and July 2018, participants underwent MRI at 1.5 Tesla for quantification of liver proton density fat fraction (spectroscopy), liver fibrosis (stiffness from elastography), left ventricular (LV) structure and function, as well as myocardial native T1 mapping. We analyzed 278 circulating cardiovascular biomarkers using a Bayesian statistica lapproach.Results: In total, 92 participants were enrolled (mean age 59.5 ± 4.6 years, 32 women). The mean liver stiffness was 2.1 ± 0.4 kPa. 53 participants displayed hepatic steatosis. LV concentricity increased across quartiles of liver stiffness. Neither liver fat nor liver stiffness displayed any relationships to myocardial tissue characteristics (native T1). In a regression analysis, liver stiffness was related to increased LV concentricity. This association was independent of diabetes and liver fat (Beta = 0.26, p = 0.0053), but was attenuated (Beta = 0.17, p = 0.077) when also adjusting for circulating levels of interleukin-1 receptor type 2.Conclusion: MRI reveals that liver fibrosis is associated to structural LV remodeling, in terms of increased concentricity, in participants from the general population. This relationship could involve the interleukin-1 signaling.
30.	Eliasson, Henrik, 1985, et al. (författare) Mitigation of nonlinearities using conjugate data repetition 2015 Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 23:3, s. 2392-2402 Tidskriftsartikel (refereegranskat)abstract We investigate a time-domain implementation of generalized phase-conjugated twin waves which we call conjugate data repetition. A theory based on time-domain perturbation analysis explaining the mitigation of nonlinear effects is provided, and the concept is evaluated using numerical simulations. Compared to PM-QPSK at the same channel bit rate, the single-channel transmission reach in a conventional system with standard single-mode fiber of conjugate data repetition-QPSK is increased by approximately a factor of 2.
31.	Eliasson, Henrik, 1985, et al. (författare) Transmitter mask testing for 28 GBaud PM-QPSK 2013 Ingår i: Optical Communication (ECOC 2013), 39th European Conference and Exhibition on. - : Institution of Engineering and Technology. - 9781849197595 ; 2013, s. 282 - 284 Konferensbidrag (refereegranskat)abstract We suggest a method for pass/fail testing of PM-QPSK transmitters. The test is based on mask testing with time-resolved EVM and accepts transmitters where individual impairments cause less than 0.5 dB OSNR penalty. The design of the test is performed by computer simulations followed by experimental verification of some key results.
32.	Eriksson, Tobias, 1986, et al. (författare) Achievable Rates Comparison for Phase-Conjugated Twin-Waves and PM-QPSK 2016 Ingår i: 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016, Niigata, Japan, 3-7 July 2016. - 9784885523052 ; , s. TuB3-3 Konferensbidrag (refereegranskat)abstract Phase-conjugated twin-waves (PCTW)-QPSK is experimentally compared to PM-QPSK in terms of achievable information rate for bit-wise decoders. For typical long-haul transmission distances, PM-QPSK with soft-decision FEC achieves significantly higher spectral efficiency than PCTW-QPSK.
33.	Eriksson, Tobias, 1986, et al. (författare) Biorthogonal modulation in 8 dimensions experimentally implemented as 2PPM-PS-QPSK 2014 Ingår i: Optical Fiber Communication Conference, OFC 2014. - Washington, D.C. : OSA. - 9781557529930 ; , s. Art. no. 6886984- Konferensbidrag (refereegranskat)abstract We experimentally demonstrate biorthogonal modulation in 8 dimensions as binary pulse-position modulation polarization-switched QPSK. We compare this format with PM-QPSK at the same bit rate and show a 1.4 dB sensitivity gain and 84 % increased transmission distance.
34.	Eriksson, Tobias, 1986, et al. (författare) Comparison of 128-SP-QAM and PM-16QAM in long-haul WDM transmission 2013 Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 21:16, s. 19269-19279 Tidskriftsartikel (refereegranskat)abstract We investigate 128-level set-partitioning quadrature amplitude modulation (128-SP-QAM) experimentally and compare the performance to polarization-multiplexed 16QAM both at the same bit rate and at the same symbol rate. Using a recirculating loop we study both single channel and wavelength-division multiplexing (WDM) transmission and demonstrate a reach of up to 2680 km at a bit-error rate of 10−3 for 128-SP-QAM. We confirm that 128-SP-QAM has an increased sensitivity compared to PM-16QAM and show that the maximum transmission distance can be increased by more than 50 % at the same bit rate for both single channel and WDM transmission. We also investigate the performance at the same symbol rate as a possible fall back solution in a degrading link.
35.	Eriksson, Tobias, 1986, et al. (författare) Experimental comparison of PS-QPSK and LDPC-coded PM-QPSK with equal spectral efficiency in WDM transmission 2014 Ingår i: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964035- Konferensbidrag (refereegranskat)abstract We compare QPSK with a rate 0.75 LDPC-code and PS-QPSK, which have the same spectral efficiency, in long-haul WDM transmission. We show that LDPC-coded PM-QPSK can achieve up to 98% increased transmission distance over uncoded PS-QPSK at BER = 10-3.
36.	Eriksson, Tobias, 1986, et al. (författare) Frequency and polarization switched QPSK 2013 Ingår i: 39th European Conference and Exhibition on Optical Communication, ECOC 2013; London; United Kingdom; 22 September 2013 through 26 September 2013. - : Institution of Engineering and Technology. - 9781849197595 ; 2013:622 CP, s. 816-818 Konferensbidrag (refereegranskat)abstract We propose 8-dimensional biorthogonal modulation as a format with 3 dB increased asymptotic power efficiency over PM-QPSK. We demonstrate one possible experimental implementation of this format based on frequency and polarization switching and compare with dual-carrier PM-QPSK and PS-QPSK.
37.	Eriksson, Tobias, 1986, et al. (författare) K-Over-L Multidimensional Position Modulation 2014 Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 32:12, s. 2254-2262 Tidskriftsartikel (refereegranskat)abstract We analyze a family of modulation formats based on multidimensional position modulation (MDPM) with multiple pulses per frame (K-over-L-MDPM) in combination with quadrature phase shift keying (QPSK), polarization multiplexed QPSK (PM-QPSK) and polarization-switched QPSK (PS-QPSK) for coherent communication systems. MDPM is a generalization of pulse position modulation where different pulse slots can be realized by time slots, polarization states, frequencies, modes of multimode fibers, cores in multicore fibers or a combination of these. We show that by using K-over-L-MDPM with QPSK, it is possible to simultaneously increase both the spectral efficiency and the asymptotic power efficiency over QPSK. We also identify K-ary inverse-MDPM (KiMDPM-QPSK) as the special case of K-over(K -1)-MDPM and show that 4iMDPM-QPSK has a 1.25 dB increased asymptotic power efficiency over QPSK with a maintained spectral efficiency.
38.	Forsgren, Mikael F, 1983-, et al. (författare) Biomarkers of liver fibrosis : prospective comparison of multimodal magnetic resonance, serum algorithms and transient elastography. 2020 Ingår i: Scandinavian Journal of Gastroenterology. - : Taylor & Francis. - 0036-5521 .- 1502-7708. ; 55:7, s. 848-859 Tidskriftsartikel (refereegranskat)abstract BACKGROUND AND AIMS: Accurate biomarkers for quantifying liver fibrosis are important for clinical practice and trial end-points. We compared the diagnostic performance of magnetic resonance imaging (MRI), including gadoxetate-enhanced MRI and 31P-MR spectroscopy, with fibrosis stage and serum fibrosis algorithms in a clinical setting. Also, in a subset of patients, MR- and transient elastography (MRE and TE) was evaluated when available.METHODS: Patients were recruited prospectively if they were scheduled to undergo liver biopsy on a clinical indication due to elevated liver enzyme levels without decompensated cirrhosis. Within a month of the clinical work-up, an MR-examination and liver needle biopsy were performed on the same day. Based on late-phase gadoxetate-enhanced MRI, a mathematical model calculated hepatobiliary function (relating to OATP1 and MRP2). The hepatocyte gadoxetate uptake rate (KHep) and the normalised liver-to-spleen contrast ratio (LSC_N10) were also calculated. Nine serum fibrosis algorithms were investigated (GUCI, King's Score, APRI, FIB-4, Lok-Index, NIKEI, NASH-CRN regression score, Forns' score, and NAFLD-fibrosis score).RESULTS: The diagnostic performance (AUROC) for identification of significant fibrosis (F2-4) was 0.78, 0.80, 0.69, and 0.78 for MRE, TE, LSC_N10, and GUCI, respectively. For the identification of advanced fibrosis (F3-4), the AUROCs were 0.93, 0.84, 0.81, and 0.82 respectively.CONCLUSION: MRE and TE were superior for non-invasive identification of significant fibrosis. Serum fibrosis algorithms developed for specific liver diseases are applicable in this cohort of diverse liver diseases aetiologies. Gadoxetate-MRI was sufficiently sensitive to detect the low function losses associated with fibrosis. None was able to efficiently distinguish between stages within the low fibrosis stages.Lay summaryExcessive accumulation of scar tissue, fibrosis, in the liver is an important aspect in chronic liver disease. To replace the invasive needle biopsy, we have explored non-invasive methods to assess liver fibrosis. In our study we found that elastographic methods, which assess the mechanical properties of the liver, are superior in assessing fibrosis in a clinical setting. Of interest from a clinical trial point-of-view, none of the tested methods was sufficiently accurate to distinguish between adjacent moderate fibrosis stages.
39.	Gao, Jitao, et al. (författare) Active Mode-Selective Conversion Enabled by an Elliptical-Core Highly Nonlinear Few-Mode Fiber 2020 Ingår i: Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS. - 1092-8081. ; 2020-May Konferensbidrag (refereegranskat)abstract We design an elliptical-core highly nonlinear few-mode fiber to achieve mode-selective conversion without parasitic wavelength conversion, using intermodal four-wave mixing. The proposed mode converter can be used in optical cross-connects over the C-band.
40.	Gao, Jitao, et al. (författare) Elliptical-Core Highly Nonlinear Few-Mode Fiber Based OXC for WDM-MDM Networks 2021 Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1558-4542 .- 1077-260X. ; 27:2 Tidskriftsartikel (refereegranskat)abstract In order to realize an optical cross-connect (OXC) converting wavelengths and spatial modes into one-dimensional switching ports, we propose an active mode selective conversion without parasitic wavelength conversion, based on the intermodal four-wave mixing (FWM) arising in a few-mode fiber (FMF). First, we design a dispersion-engineered elliptical-core highly nonlinear FMF (e-HNL-FMF) with a graded refractive index (RI) profile, which can independently guide 3 linearly polarized (LP) spatial modes. Meanwhile, a high doping concentration of germanium in the core leads to relatively high intermodal nonlinear coefficients of 3.23 (W·km)-1 between LP01 and LP11a modes and 3.14 (W·km)-1 between LP01 and LP11b modes. Next, we propose an e-HNL-FMF based OXC scheme for wavelength division multiplexing-mode division multiplexing (WDM-MDM) networks. After optimizing both the e-HNL-FMF length and pump power, we can realize either active mode selective conversion over the designated wavelength-band or three-wavelength to three-mode superchannel conversion for 100 Gbaud 16-quadratic-amplitude modulation (16-QAM) signals over the C-band. Due to excellent characteristics of the e-HNL-FMF, both cost and configuration complexity of the OXC can be reduced, showing great potentials for all-optical signal processing in the future WDM-MDM networks.
41.	Gao, J. T., et al. (författare) Design, fabrication, and characterization of a highly nonlinear few-mode fiber 2019 Ingår i: Photonics Research. - 2327-9125. ; 7:11, s. 1354-1362 Tidskriftsartikel (refereegranskat)abstract We present the design, fabrication, and characterization of a highly nonlinear few-mode fiber (HNL-FMF) with an intermodal nonlinear coefficient of 2.8 (W · km)−1, which to the best of our knowledge is the highest reported to date. The graded-index circular core fiber supports two mode groups (MGs) with six eigenmodes and is highly doped with germanium. This breaks the mode degeneracy within the higher-order MG, leading to different group velocities among corresponding eigenmodes. Thus, the HNL-FMF can support multiple intermodal four-wave mixing processes between the two MGs at the same time. In a proof-of-concept experiment, we demonstrate simultaneous intermodal wavelength conversions among three eigenmodes of the HNL-FMF over the C band.
42.	Gao, Jitao, et al. (författare) Vector mode inter-modal wavelength conversion in a dispersion tailored highly nonlinear few-mode fibre 2019 Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2019:CP765 Konferensbidrag (refereegranskat)abstract We present the design and fabrication of a dispersion tailored highly nonlinear few-mode fibre with an inter-modal nonlinear coefficient of 2.81 (W · km)-1, the highest reported to date. Inter-modal wavelength conversion between the HE21 and TE01 vector modes is demonstrated in the fibre.
43.	Grimberg, Julia, et al. (författare) Få, fler, alla måste göra mer tillsammans : En färdplan mot ett totalt försvar Annan publikation (populärvet., debatt m.m.)abstract Den svenska säkerhets- och försvarspolitiken kom snabbt att förändras under 2014 efter att Ryssland först ockuperat och sedan annekterat Krimhalvön. Sveriges verklighetsbild förändrades på några få månader, från det att Sveriges statsminister på Folk och Försvarskonferensen i Sälen i januari 2014 sagt att det var svårt att kunna tänka sig att det fanns något avgörande militära hot mot något europeiskt land. För något mer än sju år sedan, den 10 december 2015, beslutade regeringen om en återupptagen totalförsvarsplanering.Det är inom ramen för denna planering, och den svenska förmågeökning som den syftar till, som våra tankar här riktar sig till. Vi är långt ifrån klara i Sverige. Vi har precis kommit igång. Stora tankar behöver tänkas. Effekt behöver levereras.Vår uppgift är att lista utmaningar och problem i Sveriges säkerhets- och försvarspolitik inom den pågående totalförsvarsreformen och identifiera utvecklingsbehov inom svensk policy och strategi. Vi ska utmana status quo, vara framåtlutade och argumentera för de reformer som vi anser behövs.Våra slutsatser återfinns inom tre kapitelDemokratin, rättsstaten och de grundläggande fri- och rättigheterna är Sveriges främsta skyddsvärden.Ett starkt totalförsvar utifrån helhet, enkelhet och effekt.En vassare förmåga.
44.	Gustavsson, Johan, 1974, et al. (författare) High-speed 850-nm VCSELs for 40 Gb/s transmission 2010 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract We have explored the possibility to extend the data transmission rate for standard 850-nm GaAs-based VCSELs beyond the 10 Gbit/s limit of today's commercially available directly-modulated devices. By sophisticated tailoring of the design for high-speed performance we demonstrate that 10 Gb/s is far from the upper limit. For example, the thermal conductivity of the bottom mirror is improved by the use of binary compounds, and the electrical parasitics are kept at a minimum by incorporating a large diameter double layered oxide aperture in the design. We also show that the intrinsic high speed performance is significantly improved by replacing the traditional GaAs QWs with strained InGaAs QWs in the active region. The best overall performance is achieved for a device with a 9 μm diameter oxide aperture, having in a threshold current of 0.6 mA, a maximum output power of 9 mW, a thermal resistance of 1.9 °C/mW, and a differential resistance of 80 Ω. The measured 3dB bandwidth exceeds 20 GHz, and we experimentally demonstrate that the device is capable of error-free transmission (BER
45.	He, Zonglong, 1994, et al. (författare) 12.2 bit/s/Hz C-band Transmission with High-Gain Low-Complexity 24-Dimensional Geometric Shaping 2024 Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 42:14, s. 4829-4836 Tidskriftsartikel (refereegranskat)abstract Multidimensional (MD) modulation formats enable a larger minimum Euclidean distance than conventional two-dimensional formats. As a structured geometric shaping method, MD Voronoi constellations (VCs) avoid the use of look-up tables and can be implemented with low-complexity encoding and decoding algorithms, outperforming quadrature amplitude modulation (QAM) formats in terms of mutual information. However, it is challenging to maintain the shaping gain in a practical system requiring bit-mapping and forward error correction (FEC) coding. By using a hybrid labeling and multilevel coding scheme integrated with soft-decision FEC coding, MD VCs can achieve high shaping gain compared to QAM formats after soft-decision (SD) decoding. In practical systems, transceiver impairments significantly degrade the system performance, especially for high-cardinality constellations. To investigate of performance of high spectral-efficiency (SE) MD VCs, we employ a 24-dimensional (24D) VC with uncoded SE of 8 bit/symbol/dimension-pair to a spectral superchannel spanning the full C-band. Specifically, the 24D VC with a record constellation size of 7.9×10 28 is applied to dual-polarization coherent transmission over six time slots. The superchannel is composed of 5.0 Gbaud channels spaced at 5.2 GHz, resulting in an overall spectral efficiency of 12.2 bit/s/Hz and a net throughput of 54.2 Tb/s over the entire C-band after 40 km single-mode fiber. It is the first experimental demonstration of a high-SE MD format providing a significant shaping gain after SD decoding.
46.	Helgason, Òskar Bjarki, 1989, et al. (författare) Dissipative solitons in photonic molecules 2021 Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 15:4, s. 305-310 Tidskriftsartikel (refereegranskat)abstract Many physical systems display quantized energy states. In optics, interacting resonant cavities show a transmission spectrum with split eigenfrequencies, similar to the split energy levels that result from interacting states in bonded multi-atomic—that is, molecular—systems. Here, we study the nonlinear dynamics of photonic diatomic molecules in linearly coupled microresonators and demonstrate that the system supports the formation of self-enforcing solitary waves when a laser is tuned across a split energy level. The output corresponds to a frequency comb (microcomb) whose characteristics in terms of power spectral distribution are unattainable in single-mode (atomic) systems. Photonic molecule microcombs are coherent, reproducible and reach high conversion efficiency and spectral flatness while operated with a laser power of a few milliwatts. These properties can favour the heterogeneous integration of microcombs with semiconductor laser technology and facilitate applications in optical communications, spectroscopy and astronomy.
47.	Johannisson, Pontus, 1976, et al. (författare) Cancellation of Nonlinear Phase Distortion in Self-Homodyne Coherent Systems 2010 Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 22:11, s. 802-804 Tidskriftsartikel (refereegranskat)abstract Using the self-homodyne detection scheme it is possible to compensate for the nonlinear phase distortion that, if left uncompensated, would distort the received constellation diagram. The suggested compensation method is evaluated using numerical simulations and validated in an experiment.
48.	Johansson, Peter, 1967, et al. (författare) Cultural expertise in Sami land rights litigation: Epistemic strategies in the Girjas and Fosen cases 2023 Ingår i: Jindal Global Law Review. - : Springer Nature. - 0975-2498 .- 2364-4869. ; 14:2, s. 217-240 Tidskriftsartikel (refereegranskat)abstract How do parties mobilise cultural expertise in Indigenous rights litigation in Scandinavia? Recently, Sami groups have litigated to claim Indigenous rights to land and natural resources, winning some remarkable victories in the Supreme Courts of Norway and Sweden. In this paper, we draw on socio-legal mobilisation theory to analyse the epistemic strategies of Sami litigants and their adversaries in two recent landmark Supreme Court cases on Indigenous rights to usage of land: the 2020 Girjas case in Sweden and the 2021 Fosen case in Norway. Conceptualising cultural expertise as a strategic framing contest, we analyse how the parties struggled over the epistemic basis of the respective case by legitimating their claims to cultural knowledge, drawing on academic research, and discrediting their opponents’ epistemic claims. Our findings suggest that in both cases, Sami claimants successfully established an epistemic basis where their traditional, experiential knowledge combined with independent academic expertise effectively challenged the knowledge claims of their adversaries. Yet, both cases also demonstrate how the linkage between Sami Indigeneity and reindeer husbandry in the national law of both countries excludes non-reindeer herding Sami persons from the Indigenous rights affirmed by the courts.
49.	Jorgensen, A. A., et al. (författare) Petabit-per-second data transmission using a chip-scale microcomb ring resonator source 2022 Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 16:11, s. 798-802 Tidskriftsartikel (refereegranskat)abstract Optical fibre communication is the backbone of the internet. As essential core technologies are approaching their limits of size, speed and energy-efficiency, there is a need for new technologies that offer further scaling of data transmission capacity. Here we show that a single optical frequency-comb source based on a silicon nitride ring resonator supports data capacities in the petabit-per-second regime. We experimentally demonstrate transmission of 1.84 Pbit s–1 over a 37-core, 7.9-km-long fibre using 223 wavelength channels derived from a single microcomb ring resonator producing a stabilized dark-pulse Kerr frequency comb. We also present a theoretical analysis that indicates that a single, chip-scale light source should be able to support 100 Pbit s–1 in massively parallel space-and-wavelength multiplexed data transmission systems. Our findings could mark a shift in the design of future communication systems, targeting device-efficient transmitters and receivers.
50.	Karlsson, Bodil, 1976- (författare) Noctilucent clouds in a coupled atmosphere 2008 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Noctilucent clouds (NLC) at altitudes around 80 km are the highest clouds in our atmosphere. They have been a subject of research ever since their discovery in the late 19th century. This thesis takes an important step towards using NLC as a tool for studying dynamic coupling processes in the atmosphere on a global scale.Six years of NLC observations by the Odin satellite have provided information on global distribution, seasonal variation and hemispheric differences in cloud properties. Spectroscopic measurements by the OSIRIS instrument onboard Odin are used to retrieve cloud particle sizes. The ideas and challenges behind these retrievals are discussed in detail. A study of the latitudinal dependence of NLC shows a general increase of cloud occurrence, brightness, and particle sizes towards the pole. Microphysical modelling suggests that the particles grow larger near the pole because of a combined effect of colder temperature, availability of water vapour, and meridional transport times.To investigate the relationship between the cold summer mesopause region and the dynamics in the stratosphere, NLC properties derived from Odin have been used as a proxy for the state of the summer mesosphere. These data have been co-analysed with ECMWF temperatures as a proxy for the residual circulation in the stratosphere. The results of this study reveal a surprising coupling between the winter stratosphere and the summer mesopause. This interhemispheric link is suggested to be the principal cause for both year-to-year variability and hemispheric differences in summer mesosphere conditions. Further studies of the underlying dynamic coupling mechanisms were carried out using a comprehensive middle atmospheric model. As a conclusion from this study, the interannual variability in the summer polar mesopause region can be traced back to the planetary wave flux entering the winter stratosphere from the troposphere.

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