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| 3. |
- Djupsjöbacka, Anders, et al.
(author)
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Estimating Eye-opening Penalty with Aid of the Ripple Function of Fiber Bragg-gratings
- 2007
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In: Journal of Optical Communications. ; 28, s. 91-95
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Journal article (peer-reviewed)abstract
- We investigate six different methods presented in litera-ture to estimate eye-opening penalty for dispersion-com-pensating fiber Bragg gratings with aid of the grating’s ripple function. The investigation is based on theoretical ripple functions as well on measurement results of three continuously chirped gratings. The gratings in question offer full wavelength coverage between 1530 nm and 1565 nm. We will show that the eye-opening penalty de-pends on the phase and frequency of the grating’s ripple function as well as to pattern length and to pulse form of the signal used. Since the estimation methods do not ac-count for these properties, their accuracy is shown to be limited.
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| 4. |
- Djupsjöbacka, Anders, et al.
(author)
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Measured Temporal statistics of the DGD RMS-Value in Buried Optical Fibers
- 2009
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:24, s. 1801-1803
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Journal article (peer-reviewed)abstract
- The behavior of the differential group delay (DGD)root-mean-square (rms) value is investigated for a buried G.652fiber line in a metropolitan fiber plant outside Stockholm, Sweden.This study presents measurement results from two different mea-surement periods where the same fiber and the same measurementequipment was used. In total,2800 hours of measurements wereperformed. As expected, the recorded DGD rms-value variedwith time. The measured standard deviation for the statistics ofthe DGD rms-value fits reasonably well with values presentedin literature. The fiber line, which showed a DGD rms-value of0.45 ps in average, had an extremely long time constant. Evenafter2800 hours of measurements we have not closed in on theexpected asymptotic distribution of the measured DGD rms-value
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| 5. |
- Ekelund, Maria, 1970-
(author)
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Psoriasis and Temporomandibular Joint Involvement in Juvenile Idiopathic Arthritis (JIA) : A Longitudinal Study of the Nordic JIA Cohort
- 2020
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Licentiate thesis (other academic/artistic)abstract
- Juvenile idiopathic arthritis, JIA, is used as an umbrella term covering a heterogeneous group of chronic arthritis forms in children, many of which have important differences compared to adult arthritis, while others possibly represent similar diseases among children and adults. Classification aims to give a better understanding of the pathogenesis, patterns, disease trajectories and treatment responses. For the juvenile psoriatic arthritis, JPsA, the classification criteria are currently being debated. The distribution of affected joints in JIA differs greatly and it is unknown why some joints appear to be more affected than others. The temporomandibular joint (TMJ) can be affected early in the course of the disease and often the symptoms are mild and without obvious swelling.This thesis has its origin in the Nordic Study Group of Paediatric Rheumatology and the population-based prospective study of 510 children with newly diagnosed JIA included between 1997 and 1999. Totally 440 children were included in the eight-year follow-up, and in the TMJ study 265 patients were examined and underwent cone-beam computed tomography, CBCT, 17 years after onset.After eight years a considerable proportion of the children with definite psoriasis were classified as undifferentiated JIA based on the exclusion criteria in the ILAR classification. Our data also presents the heterogenicity of JPsA and the development over time of clinical variables supporting a psoriatic diathesis, as well as the overlap between JPsA and enthesitis-related arthritis in a group of patients. We found that extensive symptoms and dysfunctions of the TMJ are seen in JIA 17 years after disease onset, even in patients registered with inactive disease or remission. Individuals with substantial condylar damage on CBCT were found in all JIA categories. The deeper understanding of a chronic disease over time is crucial for research initiatives to improve care as well as for clinical decisions and planning of the health care.Our findings suggest a need for a more appropriate classification of JPsA and also that aspects of TMJ involvement should be included in the general health assessment in JIA.
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| 6. |
- Forzati, Marco, et al.
(author)
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40-gb/s field transmission through 540 km ssmf using the aprz modulation format
- 2005
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In: Optics InfoBase Conference Papers. - : Optical Society of America. - 1557527849 - 9781557527844
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Conference paper (peer-reviewed)abstract
- We report the first field transmission experiment using the APRZ modulation format for 40-Gb/s transmission through 540 km SSMF, which confirms the improved nonlinear tolerance of APRZ. The optimum phase-modulation amplitude in this experiment is p/2.
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| 7. |
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| 8. |
- Forzati, Marco, et al.
(author)
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Asynchronous Phase Modulation for the Suppression of IFWM
- 2007
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In: IEEE transactions on intelligent transportation systems (Print). - 1524-9050 .- 1558-0016. ; 25, s. 2969-75
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Journal article (peer-reviewed)abstract
- Intrachannel four-wave mixing (IFWM) represents main source of impairments in fiber transmission at 40 Gb/s. A number of phase modulation techniques have been proposed to suppress the IFWM. In this paper, we study a cost-effective way of increasing the nonlinear tolerance of a 40-Gb/s wavelength division multiplexing transmission system by asynchronous phase modulation (APM). This can be achieved with one phase modulator placed after the wavelength multiplexer so that cost is shared by all channels. We show, by means of numerical simulations and laboratory experiments, that APM greatly improves the performance of ON-OFF-keying transmission.
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| 9. |
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| 10. |
- Forzati, Marco, et al.
(author)
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Reduction of intra-channel four-wave mixing using the alternate-phase RZ modulation format
- 2002
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 14:9
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Journal article (peer-reviewed)abstract
- —The authors propose a modulation format in which the phase of the signal pulses alternates, in order to reduce the intrachannel four-wave mixing. They demonstrate numerically that the performance of a 40-Gb/s transmission link can be substantially improved.
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| 13. |
- Mårtensson, Jonas, et al.
(author)
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Phase Modulation Schemes for Improving Intra-Channel Nonlinear Tolerance in 40 Gbit/s Transmission
- 2003
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In: Conference on Optical Fiber Communication, Technical Digest Series. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 662-663
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Conference paper (peer-reviewed)abstract
- Several schemes for suppressing infra-channel non-linearities by introducing phase shifts between pulses are compared. Simulations and experiments show that sinusoidal phase modulation at 10 GHz provides a simple and effective means for improving the nonlinear tolerance in 40 Gbit/s transmission.
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| 14. |
- Mårtensson, Jonas, et al.
(author)
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Suppression of intra-channel four-wave mixing by phase modulation at one quarter of bit rate
- 2002
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In: Electronic Letters. - : Institution of Engineering and Technology (IET). - 0013-5194. ; 38:23, s. 1463-65
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Journal article (peer-reviewed)abstract
- A proposed improvement of the nonlinear tolerance in 40 Gbit/s optical transmission by applying a 10 GHz phase modulation is presented. The improvement is obtained because intra-channel four-wave mixing (IFWM) is suppressed. It is shown, both by numerical simulations and experiments, that the penalty induced by IFWM is significantly reduced.
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| 15. |
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| 16. |
- Roelens, M. A. F., et al.
(author)
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Linear frequency resolved optical gating as a line monitoring tool
- 2006
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In: 2006 Optical Fiber Communication Conference, and the 2006 National Fiber Optic Engineers Conference. - : IEEE Computer Society. - 1557528039 - 9781557528032
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Conference paper (peer-reviewed)abstract
- We demonstrate the use of spectrograms for pulse monitoring. The technique can characterize the phase and intensity of data modulated pulses after transmission over a fiber span including a tunable dispersion compensating grating. © 2006 Optical Society of America.
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| 17. |
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| 18. |
- Öhman, F., et al.
(author)
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Measurements and simulations of nonlinear noise redistribution in an SOA
- 2005
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 17:1, s. 16-18
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Journal article (peer-reviewed)abstract
- Measurements and numerical simulations of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate nonlinear noise redistribution. The redistribution, which relies on self-modulation due to gain saturation and carrier dynamics, shows a strong power and bandwidth dependence and can be important for SOA-based regenerators. © 2005 IEEE.
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| 19. |
- Öhman, F., et al.
(author)
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Measurements of non-linear noise re-distribution in an SOA
- 2004
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In: Conference on Lasers and Electro-Optics, 2004. (CLEO)..
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Conference paper (peer-reviewed)abstract
- Measurements of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate non-linear noise re-distribution with a strong power and bandwidth dependence.
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| 20. |
- Alberdi-Saugstrup, Mikel, et al.
(author)
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High-sensitive CRP as a predictive marker of long-term outcome in juvenile idiopathic arthritis
- 2017
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In: Rheumatology International. - : SPRINGER HEIDELBERG. - 0172-8172 .- 1437-160X. ; 37:5, s. 695-703
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Journal article (peer-reviewed)abstract
- To evaluate whether C-reactive protein (CRP), including variation within the normal range, is predictive of long-term disease outcome in Juvenile Idiopathic Arthritis (JIA). Consecutive patients with newly diagnosed JIA were included prospectively from defined geographic areas of the Nordic countries from 1997 to 2000. Inclusion criteria were availability of a baseline serum sample within 12 months after disease onset and 8-year clinical assessment data. Systemic onset JIA was not included. CRP was measured by high-sensitive ELISA (detection limit of 0.2 mg/l). One hundred and thirty participants with a median follow-up time of 97 months (range 95-100) were included. At follow-up, 38% of the patients were in remission off medication. Absence of remission was associated with elevated level of CRP at baseline (odds ratio (OR) 1.33, confidence interval (CI) 1.08-1.63, p = 0.007). By applying a cutoff at the normal upper limit (> 10 mg/l), the risk of not achieving remission was increased to an OR of 8.60 (CI 2.98-24.81, p < 0.001). Variations of CRP within the normal range had no predictive impact on disease activity at follow-up. Baseline levels of ESR were available in 80 patients (61%) and elevated ESR was associated with absence of remission in a multivariable logistic regression analysis (OR 2.32, CI 1.35-4.00, p = 0.002). This results of this study indicate that baseline CRP concentrations above 10 mg/l are predictive of a poor outcome at 8-year follow-up. We could not demonstrate any predictive value of CRP variations within the normal range.
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| 21. |
- Alberdi-Saugstrup, M, et al.
(author)
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Non-HLA gene polymorphisms in juvenile idiopathic arthritis: associations with disease outcome.
- 2017
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In: Scandinavian journal of rheumatology. - : Informa UK Limited. - 1502-7732 .- 0300-9742. ; , s. 1-8
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Journal article (peer-reviewed)abstract
- To test the hypothesis that non-HLA single-nucleotide polymorphisms (SNPs) associated with the risk of juvenile idiopathic arthritis (JIA) are risk factors for an unfavourable disease outcome at long-term follow-up.The Nordic JIA cohort is a prospective multicentre study cohort of patients from the Nordic countries. In all, 193 patients met the inclusion criteria of having an 8year follow-up assessment and available DNA sample. Seventeen SNPs met the inclusion criteria of having significant associations with JIA in at least two previous independent study cohorts. Clinical endpoints were disease remission, actively inflamed joints and joints with limitation of motion (LOM), articular or extra-articular damage, and history of uveitis.Evidence of associations between genotypes and endpoints were found for STAT4, ADAD1-IL2-IL21, PTPN2, and VTCN1 (p=0.003-0.05). STAT4_rs7574865 TT was associated with the presence of actively inflamed joints [odds ratio (OR) 20.6, 95% confidence interval (CI) 2.2->100, p=0.003] and extra-articular damage (OR 7.9, 95% CI 1-56.6, p=0.057). ADAD1_rs17388568 AA was associated with a lower risk of having joints with LOM (OR 0.1, 95% CI 0-0.55, p=0.016). PTPN2_rs1893217 CC was associated with a lower risk of having joints with LOM (OR 0.2, 95% CI 0-0.99, p=0.026), while VTCN1_rs2358820 GA was associated with uveitis (OR 3.5, 95% CI 1-12.1, p=0.029).This exploratory study, using a prospectively followed JIA cohort, found significant associations between long-term outcome and SNPs, all previously associated with development of JIA and involved in immune regulation and signal transduction in immune cells.
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| 22. |
- Anders, Berntson, et al.
(author)
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Analysis of coherent and incoherent interactions of amplitude shifted solitons in optical fibres
- 1995
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In: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 52:5, s. 544-553
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Journal article (peer-reviewed)abstract
- Nonlinear interaction between pulses can severely reduce the bit-rate of an optical communication system. One way of reducing this interaction is amplitude shifting of consequtive pulses. In the present work a detailed analytical and numerical investigation is made of the coherent and incoherent interactions between two soliton pulses of unequal amplitudes. For the case of coherent interaction the obtained expressions for the pulse parameters in terms of initial phase and amplitude differences give a clear and explicit prediction of the reduction of the interaction strength for unequal soliton amplitudes. A comparison with numerical simulation results shows good agreement. For the case of incoherent soliton interaction it is found that the dependence of the interaction strength on the amplitude difference is weak.
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| 23. |
- Anders, Berntson, et al.
(author)
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Analysis of coherent and incoherent interactions of amplitude shifted solitons in optical fibres
- 1998
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Reports (other academic/artistic)abstract
- Nonlinear interaction between pulses can severely reduce the bit-rate of an optical communication system. One way of reducing this interaction is amplitude shifting of consecutive pulses. In the present work a detailed analytical and numerical investigation is made of the coherent and incoherent interactions between two soliton pulses of unequal amplitudes. For the case of coherent interaction the obtained expressions for the pulse parameters in terms of initial phase and amplitude differences give a clear and explicit prediction of the reduction of the interaction strength for unequal soliton amplitudes. A comparison with numerical simulation results shows good agreement. For the case of incoherent soliton interaction it is found that the dependence of the interaction strength on the amplitude difference is weak.
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| 24. |
- Anders, Berntson, et al.
(author)
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Dispersion management with filtering
- 1998
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Reports (other academic/artistic)abstract
- We present results of analytical and numerical consideration of the pulses in a model of a DM fiber link including the fixed-frequency filters and compensating gain, both taken in the distributed approximation. Combining the variational approximation and perturbative treatment of the filtering and gain terms, we predict stationary propagation regimes. The most important new features are the absence of the minimum DM strength necessary for the existence of the pulses in the case when the average dispersion is nil or normal, and the existence of a minimum necessary normalized power in this case. These features are well corroborated by direct simulations.
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| 25. |
- Anders, Berntson, et al.
(author)
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Dispersion management with filtering
- 1999
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In: Optics Letters. - : Optical Society of America Inc.. - 0146-9592 .- 1539-4794. ; 24:8, s. 507-509
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Journal article (peer-reviewed)abstract
- With regards to their potential to improving the pulse-based regimes in optical communication networks, dispersion-managed solitons in a fiber link including guiding filters and compensating gain were investigated. Combining the variational approximation and the perturbative treatment of the filtering and gain, stationary regimes are predicted. Among other features, the minimum map strength necessary for the existence of the pulses when path-averaged dispersion (PAD) is zero or normal is absent, rather, a minimum necessary normalized power for any PAD exists.
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